tue

ur Uien uy cht

soees ieee eect

piseeisate cn
fees

SE aS SESS R Gyr

 
   
  

     

 

   

a

4)

Gornell University Library
Sthara, Nem York

 

THE

CHARLES EDWARD VAN CLEEF
MEMORIAL LIBRARY

FROM
REGIONAL ANATOMY

IN ITS RELATION TO

MEDICINE AND SURGERY.

BY

GEORGE McCLELLAN, M.D.,

LECTURER ON DESCRIPTIVE AND REGIONAL ANATOMY AT THE PENNSYLVANIA SCHOOL OF ANATOMY, PROFESSOR OF
ANATOMY AT THE PENNSYLVANIA ACADEMY OF THE FINE ARTS, MEMBER OF THE ASSOCIATION OF
AMERICAN ANATOMISTS, ACADEMY OF NATURAL SCIENCES, ACADEMY OF SURGERY,

COLLEGE OF PHYSICIANS, ETC., OF PHILADELPHIA.

ILLUSTRATED FROM PHOTOGRAPHS TAKEN BY THE AUTHOR OF
HIS OWN DISSECTIONS, EXPRESSLY DESIGNED AND
PREPARED FOR THIS WORK, AND COLORED

BY HIM AFTER NATURE.

“TL’anatomie n’est pas telle qu’on l’enseigne dans les écoles.””—BicH art.

IN TWO VOLUMES.
VOL. I.

PHILADELPHIA:
PUBLISHED BY THE AUTHOR.

1898.

le
Copyright, 1890, by Gzoraz McCretzayn, M.D.
TO THE MEMORY

OF MY FATHER,

JOHN H. B. McCLELLAN, M.D.,

AND OF MY GRANDFATHER,

GEORGE McCLELLAN, M.D.
PREFACE TO THE FOURTH EDITION.

Ir is seven years since this book was first offered to the Profession, and as
substantial proof of the recognition it has received it may be stated that with this
edition it reaches the tenth thousand.

In the face of the many difficulties incidental to an undertaking of such
magnitude, this fact is very encouraging. The certainty that the work has
won its way, in spite of the nature of the subject of which it claims to be a new
exposition, notwithstanding the number of text-books with which it has entered into
competition, is most gratifying to the author. Dearer still to him as an Anatomist
would be the thought that through his endeavor the science of the study to
which he has devoted much of his life had come to be more exactly known.

The text and illustrations of the present edition are in all respects identical
with those of the last. The only improvement consists in a complete index to the series
of plates, covering twenty-seven extra pages, which the author has added to the
second volume. This has been no light task, and it is hoped this index will be
found useful. It certainly will assist any one who may wish to see what the

scalpel has revealed of any of the separate regions referred to in the text.

GEORGE McCLELLAN, M.D.
BROAD AND SPRUCE STREETS,
PHILADELPHIA, July, 1898.
PREFACE TO THE SECOND EDITION.

Tart five thousand copies of Regional Anatomy have already been disposed
of in America and England, and that the text is in progress of translation into
French and German, are gratifying proofs of its favorable reception by the profession.

In venturing to present a second edition the author takes occasion to acknowl-
edge the many kindly notices and reviews which have been bestowed upon his work.

The text has been thoroughly revised, and the reproduction of the illustrations
from the original stones has received unremitting care from the lithographers, whose
experience has enabled them to overcome some of the difficulties of producing the
desired colors on the steam press, so that it is believed in this respect their work will
be found to excel that of the first edition.

The stones from which the illustrations of the brain are now presented have
mostly been re-drawn from the original photographs.

No one can more fully realize the shortcomings of the work than does the author,
who assures his readers that he will at all times be grateful for any suggestions which
may occur to them as likely to render his effort more complete and thereby assist

him in his chief aim, the advancement of the knowledge of anatomy.

BROAD AND SPRUCE STREETS,
PHILADELPHIA, May, 1894.
PREFACE TO THE FIRST EDITION.

THERE has been a great deal said of the importance of anatomical knowledge,
which is universally conceded to be the foundation of the study of medicine.

As a teacher of anatomy, I have used all my influence to impress this on the
minds of students, assuring them that the best book on anatomy is, and always will be,
the body itself.

In the curricula of the colleges and universities this is emphasized by a compulsory
course in the dissecting-room, and each candidate for a degree is obliged to dissect three
parts—the head, and the extremities, with contiguous portions of the trunk—at least
once. From the knowledge gained by these dissections, and from lectures and text-
books, a student is supposed to acquire the information necessary to enable him to work
intelligently and beneficially in his profession. He is expected to learn anatomy from
his three parts.

Considering the facts that the first part is generally wasted in acquiring the
methods of using the instruments ; that all the parts are seldom carefully injected with
proper preservative; that the student rarely has the opportunity of seeing the viscera
of the cranium, thorax, and abdomen in situ, much less of examining them and noting
their size or structure and their relative positions to one another and to the cavities
which contain them ; and that often the value of the opportunity is not estimated until
it is lost, it cannot be a matter of wonder that students look upon anatomy as one of
their chief difficulties, and that only a few continue its study after graduation. There
are many practical obstacles in the way of obtaining better and more abundant material
for such research ; but, after some years’ experience, I am forced to acknowledge that,
even if these obstacles were overcome, the distaste for the actual labor of dissecting,
which, besides being exacting, is associated with much that is revolting, and even haz-
ardous to health, would deter many students from gaining that practical knowledge
from personal observation which would enable them to recognize the different tissues
by the sense of touch as well as by the sense of sight.

In a crowded lecture-room only those who are very near can see the demonstrations
so as really to profit by them. Extempore drawings are of great value in awakening and
retaining the interest of students, whose memories are often overtasked, and have an
advantage over the most carefully prepared diagrams, models, or preparations; but there

v
vi PREFACE.

cannot be any means of illustration equal to the real thing in teaching, and the best
substitute is that which aims at producing the most realistic impressions. Such illus-
trations have been attempted in the plates for the present work.

Regional Anatomy, or the anatomy of the different regions of the body individ-
ually considered, in the relations of their parts to one another, as they are naturally
found, is really the most direct method of studying the subject. It is also the most
useful form of anatomical research, and, although it may at first sight seem more
difficult because it presents a complex in the place of a simple object, such as was
demonstrated in the old method of considering the bones, the ligaments, the muscles,
the vessels, and the nerves as so many distinct structures, the greater interest soon
growing from the evidence of its practical usefulness fully compensates for the effort
required.

The interest which my classes have shown in this treatment of anatomy has
led me to undertake this work. It is largely the result of information acquired by
dissecting, and of clinical observations in hospital and private practice. In its
preparation I have consulted such ancient and modern books on anatomy as I
could obtain, and have gleaned from them much information which suggested many
of the dissections showing relations of structures. No quotation from or direct refer-
ence to these works, however, is introduced in the text, which has also, for the sake
of clearness, been kept free from notes. . .

Assuming some previous knowledge of the bones on the part of the reader, I
have exercised the privilege of adopting such modifications in the nomenclature as may
render certain parts more easily comprehended, but have retained such names and
terms as have an historic association, believing that they add to the interest and fasten
themselves on the memory, rather than detract from the mastery of so difficult a study.
It is to be regretted that anatomy loses much in consequence of the want of a definite
nomenclature. The suggestions of modern writers as to technical terms, if accompanied
by a corresponding clearness of description, might be of benefit to the student; but,
while not underrating the importance of scientific exactness of expression, I am of
the opinion that the ordinary student’s attention soon wearies of technicality, whether
written or spoken, and I have therefore made use of such terms in my text as experience
has shown to be most easily understood and remembered. Anatomy, to be of use,
must be made a practical and not a theoretical study. It is difficult enough pro re
nata, and, if hard, need not be dry.

Should the present book fulfil its mission, it will be by presenting the matter in a
new form, which it is hoped will prove interesting and useful, alike to the practitioner and
to the student who intends to practise. The plates are expressly prepared to illustrate
and verify the descriptions, and are as faithful representations of the dissections as they
could be made. It should be borne in mind, however, that no true picture of the
actual subject will have the distinct demarcation and clearness of a diagram, any more
than the representation of a natural landscape indicates mountains, rivers, and boundary
lines with the exactness of a map. Diagrams will therefore always be useful to the
student in showing him what he ought to see, but such illustrations as are here attempted
PREFACE. vu

should be valuable in enabling him to recognize things as they actually are. These
representations are intended to meet the need both of the beginner in dissecting, who
is appalled by the want of correspondence between that which he actually sees and
that which he has been led to expect by diagrams or description, and of those whose
time is too gravely occupied by the pressure of professional duties to warrant their
dissecting for themselves. Accuracy has been the chief object, and I have relied upon
the unfailing precision of the camera to present the true relations of the parts, which
were in each case left in situ, only the adipose and connective tissues being removed,
to give distinct impressions. Much thought, time, and expense have been given to
the photographic details, such as the arrangement of the light to modify the shadows,
the exposure and development of the negatives, and the subsequent printing and toning
of the pictures to get the desired effect for the application of the water-colors. The
coloring of the originals from which the plates were made on stone, under my personal
supervision, was a study from nature, with perhaps some excess of tint or shade, as
might be expected where the paints were mixed and applied with more enthusiasm than
artistic skill.

The dissections, in all about three hundred, were invariably the work of my own
scalpel, and were all done upon subjects selected as best showing the normal relations
of the parts, without pathological change, while such facts as seem valuable regarding
the condition or modes of preparation are mentioned in the description of every plate.
Each figure is also accompanied by a separate and complete explanatory table,—every
number being placed in regular order, so that any object may be readily found.

To Messrs. Lippincott Company, the publishers, my thanks are due for the warmth
with which they have entered into my undertaking, for the strong sympathy and in-
terest they have shown in my work, and for the care which they have taken to present
the text to the reader in a clear and attractive form.

To Messrs. Armstrong & Co., of Boston, I am indebted for their painstaking
fac-simile reproductions of my systematized views of dissections, which preserve the
photographie accuracy and the realistic effect of the coloring of the originals, and
which not only ought to render this an acceptable text-book, but should also awaken
a keener interest in the study of Regional Anatomy.

GEORGE McCLELLAN.

PHILADELPHIA, OcToBER, 1890.
CONTENTS OF VOLUME {

THE REGION OF THE HEAD .. . pages 1-60
Surface-Form and Landmarks of the Skull. = of — Head. — ichaibe. —Tables of the
Skull.—Diploic Structures.—Fontanelles.— Foramina.—Scalp.—Scalp Hair.—Arteries
of the Scalp.—Veins of the Scalp.—Lymphatic Vessels of the Scalp.—Nerves of the.
Scalp.—Occipito-Frontalis Muscle.—Aponeurosis of the Scalp.—Epicranium.—Peri-
eranium.—Temporal Fascia.—Thickness of the Skull-Cap.—Dura Mater.—Pacchi-
onian Bodies.—Tentorium.—Falx Cerebri.—Falx Cerebellii—Arteries of the Dura
Mater.—Arachnoid.—Cerebro-Spinal Fluid.—Pia Mater.—Arteries of the Brain.—The
Brain.—Lobes of the Cerebrum.—Primary Fissures of the Hemispheres.—Secondary
Fissures of the Hemispheres.—Fissure of Rolando.—Sylvian Fissure.—Parieto-Occip-
ital Fissure ——Hippocampal Fissure.—Transverse Fissure.—Interparietal Fissure.—
Convolutions of the Brain.—Cranio-Cerebral Topography.—Base of the Cerebrum.—
Cranial Nerves.— Medulla Oblongata.— Pons Varolii.—Cerebellum.— Fourth Ven-
tricle—Aqueduct of Sylvius.—Third Ventricle.—Foramen of Monro.—Lateral Ven-
tricles. — Fornix.—Septum Lucidum.—Fifth Ventricle.— Corpus Striatum.—Optic
Thalamus.—Corpus Callosum.—Diverging Fibres of the Medullary Structure.

THE RHGION OF THE EAR . Fi : if ‘ ‘ * ‘ 3 pages 60-79

Pinna, or Auricle.—Cartilages of the Auricle.—Ligaments and Muscles of the Auricle.—

Arteries, Veins, and Nerves of the Auricle.—Auditory Meatus.—Membrana Tym-

pani.—Tympanum, or Middle Ear.—Ossicles.—Facial Nerve within the Temporal

Bone.—Internal Ear, or Labyrinth.—Organ of Corti.—Auditory Nerve.—Auditory
Artery and Auditory Vein.

THE ORBITAL REGION AND THE EYE. : : a ‘ pages 79-107
Walls of the Orbits.—Eyebrows.—Eyelids.—Muscles of the Byelids, —Lachrymal Gland.
—Conjunctiva.—Cornea.—Sclerotic Coat.—Muscles of the Eyeball. —Capsule of Tenon.
—Sensory Nerves of the Orbit.—Ophthalmic or Ciliary Ganglion.—Ophthalmic Ar-
tery.—Optic Nerve.—Choroid Coat.—Ciliary Muscles.—Iris.—Pupil.--Aqueous Humor.
—Crystalline Lens.—Vitreous Body.—Retina.—Porus Opticus.

THE REGION OF THE NOSH AND THE NASAL CAVITIES . pages 107-116
Nasal Bones.—Cartilaginous Framework of the Nose.—Muscles in connection with. the
Nose.—Arteries, Veins, and Lymphatics of the Nose.—Nerves of the Nose.—Nasal
Fosse or Cavities.—Infundibulum.—Nasal Meatuses.—Nasal Duct.—Schneiderian
Mucous Membrane and Olfactory Cells.—Anterior and Posterior Nares.—Vessels of
the Nasal Cavities.—Olfactory Nerves.
ix
x CONTENTS.

THE REGION OF THE FACE 4 ‘ s : pages 116-130

Landmarks of the Face.—Skin of the Face. Syisties of ihe Face. —Arteries of the Face.

—Sensory Nerves of the Face.—Branches of the Trifacial Nerve of the Face.—Motor
Nerves of the Face.

THE REGION OF THE PAROTID GLAND . : ‘ j : pages 1380-186
Parotid Fascia.—Duct of Stenson.—Extra- and Intra-Parotid Lymphatic Glands.—
Branches of the External Carotid Artery in relation to the Parotid Gland.—Lobes
of the Parotid Gland.—Branches of the Facial Nerve (Pes Anserinus) in relation

to the Parotid Gland.—Removal of the Parotid Gland.

THE DEEP STRUCTURES OF THE FACE . ‘ a . ‘ pages 136-148
Landmarks.—Temporo-Maxillary Joint.—Pterygoid Muscles.—Branches of the Internal
Maxillary Artery and Vein.—Spheno-Palatine or Meckel’s Ganglion.—Branches of
the Inferior Maxillary Nerve.—Otic Ganglion.—Superior Maxillary Bones.—Antra
of Highmore.—Palatine Canals and Foramina.—The Incisive Bone in relation to

Cleft Palate. .

THE REGION OF THE MOUTH . : a z ‘ pages 148-175

Lips.—Coronary Arteries.—Buccal Glands.—Gums aa Teeth. —Cavity of the Mouth.—

Hard Palate.—Soft Palate.—Pillars of the Palate.—Muscles of the Palate.—Vessels

and Nerves of the Palate.—Tongue.—Papille.—Muscles of the Tongue.—Sublingual

Salivary Gland.—Submaxillary Salivary Gland.—Hyoid Bone.— Lingual Artery.

—Exposure of the Lingual Artery for Ligation.— Motor Nerve (Hypoglossal) to

the Tongue.—Sensory Nerves (Lingual and Glosso-Pharyngeal) to the Tongue.—

Submaxillary Ganglion.—Lymphatic Vessels to the Tongue.—Fauces.—Tonsils.—
Pharynx.—Muscles of the Pharynx.—Eustachian Tube,

THE REGION OF THE LARYNX ‘i ‘ ‘ ‘ pages 175-187

Cartilages of the Larynx.—Thyroid, Cricoid, and Reciorsia, _Rpiglottis. —Vocal Cords.

—Glottis.—_Intrinsic Muscles of the Larynx.—Extrinsic Muscles of the Larynx.—
Nerves and Vessels of the Larynx.

THE REGION OF THH NECK . 3 3 4 pages 187-240
Landmarks.—Skin on the Neck.—Platysma Myoides Wixtle, —Cutaneous Nerves and
Vessels of the Neck.—Deep Fascia and its Reflections.—Sterno-Cleido-Mastoid Mus-
cle.—Triangles of the Neck.—Digastric Muscle.—Omo-Hyoid Muscle.—Common
Carotid Artery and Jugular Vein.—Inter-Carotic Body.—Pneumogastrie Nerve in
the Neck.—Glosso-Pharyngeal.—Descendens Hypoglossi.i—Deep Cervical Plexus of
Nerves.—Deep Muscles at the Side of the Neck.—Trapezius Muscle.—Deep Mus-
cles at the Back of the Neck.—Cervical Spinal Nerves.— Vertebral Arteries.—
Cervical Vertebree and their Ligaments.—Cervical Portion of the Sympathetic
Nerve and Ganglia.—Scalene Muscles.—Structures collected at the Root of the
Neck.—Deep Cervical Lymphatic Glands.—Subclavian Arteries.—Subclavian Veins.
—Ligation of the Subclavian Arteries.—Thyroid Body.—Trachea.— Operation of
Tracheotomy.
.

CONTENTS. Xl

THE REGION OF THE THORAX a oo.) el pages 240-820
Skeleton of the Thorax.—Ribs and their Articulations.—Sternum.—Intercostal Spaces.—
Dorsal or Thoracic Vertebree.—Skin on the Anterior Surface of the Thorax.—Mam-
mary Glands.—Vessels and Nerves of the Mammary Glands.—Operation for Removal
of the Breast.—Deep Fascia of the Anterior Surface of the Thorax.—Pectoralis
Major and Minor Muscles.—Costo-Coracoid Membrane.—Intercostal Muscles.—Tri-
angularis Sterni Muscle.—Internal Mammary Artery.—Anterior, Middle, and Poste-
rior Mediastina.—Thymus Gland.—Pleure.—Pleural Sinuses.—The Lungs.—Relation
of the Lungs in Expiration and Inspiration.—Fissures of the Lungs.—Lobes of the
Lungs.—Roots of the Lungs—Ligamenta Lata Pulmonalia.—Bronchi.—Lobules.—
Structure of the Lungs.—Bronchial Glands.—Pulmonary Vessels and Nerves.—Peri-
eardium.—The Heart.—Relative Position of the Heart to the Walls of the Thorax.
—Exterior of the Heart.—Coronary Arteries.—Shape of the Heart.—Auricles and
Ventricles of the Heart.—Openings and Valves of the Heart.—Structure of the
Heart.— Nerves and Lymphatic Vessels of the Heart.—Superior Vena Cava. —
Relations of the Different Parts of the Aorta.— Anomalous Distribution of the
Great Vessels from the Aorta, and Condition of the Heart—Common Pulmonary
Artery.—Pulmonary Veins.—Systemic Arteries, and their Variations in Different
Localities.—Anastomosis of Arteries.—Structure of the Walls of the Arteries.—
Systemic Veins, and their Variations in Different Localities.—Superficial and
Deep Veins.—Venz Comites.—Structure of the Walls of the Veins.—Capillaries.
—Vaso-Motor Nerves.—The Blood. — Developmental Changes in the Heart and
Vascular System.—Ductus Venosus.—Ductus Arteriosus.—Hypogastric Arteries.—
Umbilical Arteries.—The Foetal Heart, and the Circulation of the Blood before Birth.
—Heart-Sounds.—Arterial Pulse.—Topographical Survey of the Chest for Clinical
Study of the Relative Positions of the Heart and Lungs.—Descending Thoracic
Aorta and its Branches.—Csophagus.—Operation of Cisophagotomy.—Pneumogas-
tric Nerves in the Thorax.—Thoracic Duct.—Azygos Veins.—Splanchnic Nerves.

THE DIAPHRAGM : : : z : : pages 320-323
Ligamenta Arcuata.—Openings in the Dinphiearn: —Aessarg and Nerves of the Diaphragm.

THE REGION OF THE SHOULDER . ‘ . : a pages 323-337

Shoulder-Girdle.— Clavicle. —Scapula.— Muscles of ‘ie Beal —Upper End of the

Humerus.—Shoulder-Joint.—Capsular Ligament.—Tendons of the Muscles in rela-

tion to the Shoulder-Joint.—Burse in relation to the Shoulder-Joint.—The Deltoid

Muscle and its Insertion.—Grouping of the Muscles in effecting the Various Move-

ments of the Shoulder.—Dislocations of the Shoulder.—Fractures at the Shoulder.—
Relations of the Parts in Amputation at the Shoulder. ‘

THE REGION OF THE AXILLA. ... . «~~ ~pages 837-348
Axillary Folds.—Axillary Fascia. —(aivigeensci ley Bandage. —Relations of the Cuta-
neous Branches of the Intercostal Nerves to the Axilla.—Axillary Artery and its
Branches.—Axillary Veins.—Brachial or Axillary Plexus of Nerves.—Lymphatic
Glands of the Axilla.
xii CONTENTS.

THE REGION OF THE ARM. zi é : 5 7 pages 348-362
Lower Portion of the Humerus. apthonndyies ani Bupa Cendyiaia Ridges.—Surface-
Marking.—Skin.—Bicipital Depressions.—Deep Fascia of the Arm.—Hiatus Semilu-
naris.—Biceps Muscle.—Brachialis Anticus Muscle.—Triceps Muscle.—Brachial Ar-

tery and its Branches.—Operation for Ligating the Brachial Artery.—Venz Comites

of the Brachial Artery.—Branches of the Brachial Plexus in the Arm.—Median
Nerve.—Musculo-Cutaneous Nerve.—Ulnar Nerve.—Internal Cutaneous Nerve, and
Musculo-Spiral Nerve.—Fractures of the Shaft of the Humerus.—Relations of the

Parts in Amputation through the Middle of the Arm.—Ossification of the Humerus.

THE REGION OF THE ELBOW . Pano : . pages 362-372
Upper Ends of the Ulna and Radius.—Elbow-Joint. _iehio: Radio-Ulnar Joint.—Skin
over the Front of the Elbow.—Superficial Veins at the Bend of the Elbow.—Bursze
about the Elbow.—Dislocation at the Elbow.—Fractures at the Elbow.—Relations of

the Parts in Amputation at the Elbow.—Resection of the Elbow.

THE REGION OF THE FOREARM . ‘ ; ‘ 3 pages 372-396

Shafts and Lower Ends of the Radius and Ulna. _farriGy ‘Radio- Ulnar Joint.—Inter-

osseous Ligament.—Humero-Ulnar Shaft.—The Skin over the Forearm.—Superficial

Radial Vein.—Cutaneous Nerves of the Forearm.—Deep Fascia of the Forearm.—

Muscles of the Forearm.—Radial Artery and its Branches.—Ulnar Artery and its

Branches.—Median Nerve in the Forearm.—Branches of the Musculo-Spiral Nerve

in the Forearm.—Fractures of the Bones in the Forearm.—Development of the

Radius and Ulna.—Relations of the Parts in Amputation through the Middle of the
Forearm.

THE REGION OF THE WRIST AND THE HAND . . 5 pages 396-418
Carpal Bones.—Radio-Carpal or Wrist Joint.—Triangular Fibro-Cartilage.—Synovial
Membrane.—Ligaments of the Wrist.—Movements at the Wrist-Joint.—Metacarpal
Bones.—Phalanges.—Metacarpo-Phalangeal Joint.—Interosseous Muscles. — Dorsal
Aponeurosis of the Fingers.—Joint of the Thumb with the Trapezium.—Muscles of
the Ball of the Thumb.—Muscles of the Ball of the Little Finger.—Surface-Markings
of the Wrist and Hand.—Skin over the Wrist.—Superficial Veins and Nerves.—Pos-
terior Annular Ligament.—Skin over the Back of the Hand.—Superficial Veins of
the Hand.—Branches of the Radial Nerve.—Radial Artery passing between the
First and Second Metacarpal Bones to enter the Palm.—Branches of the Ulnar
Nerve.—Palm of the Hand.—Thenar Eminence.—Hypothenar Eminence.—Linea
Vitalis —Linea Cephalica.—Linea Mensalis.—Linea Hepatica.—Plica Interdigitalis.
—Subcutaneous Tissue of the Palm.—Palmar Fascia.—Anterior Annular Ligament.
—Superficial Arterial Palmar Arch.—Deep Arterial Palmar Arch.—Wounds of the
Palm.—Distribution on the Fingers of the Ulnar Nerve.—Distribution of the Median
Nerve on the Fingers.—Superficial Lymphatic Vessels of the Palmar and Dorsal
Surfaces of the Hand.—Nails.—Growth of the Nails.—Relation of the Parts in
Amputations of the Fingers.—Development of the Bones of the Wrist and Hand.
LIST OF ILLUSTRATIONS TO VOLUME L.

PLATE 1.

The landmarks of the skeleton of the regions of the head, face, and neck, on the right side,
with their relations to the surface coverings.

. PLATE 2.
Figure 1,

Skull showing a topographical survey of the relations of the sutures and eminences to the
principal fissures of the brain, and the approximate lower level line of the cerebrum.

Figure 2.

The left side of a skull, with the parietal bone removed, showing the subjacent convolutions of
' the left cerebral hemisphere (stripped of their membranes), with a topographical survey
of the motor area of the opercular region thus exposed.

PLATE 3.
Figure 1.

The base of the skull seen from within, showing the exits of the cranial nerves. The dura
mater lining the fosse of the skull is retained, surrounding and forming sheaths for all
the nerves which are left in situ after the removal of the brain. (From a female head aged
twenty-one years.)

Figure 2.

The distribution of the branches of the trifacial (or fifth cranial) nerve, and their relation to
the branches of the internal maxillary artery.

Figure 3.

The posterior view of an adult European skull (the norma occipitalis). Showing remarkable
Wormian bones (or ossa triquetra). Nos. 4 and 13.

Figure 4.

The right side of a skull of an adult male, with the outer table rasped away, to show the
diploic veins.
Figure 5.

Oblique section through the left temporal bone, to show the tympanic cavity and mastoid
cells on one side, and on the other the membrana tympani, the ossicles, and the Eusta-
chian tube. rs

xiii
Xiv LIST OF ILLUSTRATIONS TO VOLUME I.

PLATE 4.
Figure 1.

The right hemisphere of the cerebrum removed, to show the falx cerebri and tentorium of
the dura mater, and the relations of the great sinuses and their tributaries. (From same
head as in Plates 9 and 10.)

Figure 2.

The posterior third of the skull and its scalp removed, to show the posterior view of the dura
mater, and the confluence of the lateral and occipital sinuses with the superior longitudi-
nalsinus. Also the posterior segments of the cervical vertebre are removed, to show the
continuation of the dura mater of the brain with that of the spinal cord, the ganglions
on the posterior roots of the cervical nerves, aud the course of the vertebral arteries
through the vertebral foramina.

PLATE 5.
Figure 1.

The pia mater, with its vessels ramifying over the convolutions on the upper surface of
the hemispheres. The longitudinal sinus in position, with clusters of the Pacchionian
granules within it and upon either side.

Figure 2.

The base of the skull, with the cerebellum retained in the occipital fosse. Portions of the

orbital roofs are removed, to show the nerves and muscles passing to the eyeballs.
Figure 3.

The base of the brain, showing the anastomosis of the arteries called the circle of Willis.
(From an adult male.)

PLATE 6.
Figure 1.

The upper surface of the brain of a white man about forty-five years of age, in sound con-
dition and normal in general conformation, size, and weight. The right hemisphere is
larger than the left, the longitudinal fissure not being in the middle of the cerebral mass.
The pia mater has been removed, to demonstrate the surface-markings.

Figure 2.

The under surface of the same brain as in Figure 1, showing the superficial origins of the
cranial nerves. The pia mater is removed from the cerebrum, although retained over the
cerebellum.

PLATE 7.
Figure 1.

The convolutions and fissures on the external surface of the right hemisphere. (From same
brain as in Plate 6.)
Figure 2.

The convolutions and fissures on the external surface of the Jefé hemisphere. (From same
brain as in Plate 6.)

PLATE 8.
Figure 1.

The convolutions and fissures of the inner surface of the Jeft hemisphere of the cerebrum, and
median section through the base of the brain, cerebellum, pons Varolii, and medulla
oblongata. (From same brain as in Plates 6 and 7.)
LIST OF ILLUSTRATIONS TO VOLUME I. XV

Figure 2.

The convolutions and fissures of the inner surface of the right hemisphere of the cere-
brum, and median section through the base of the brain, cerebellum, pons Varolii, and
medulla oblongata. (From same brain as in Plates 6 and 7.)

N.B.—All the figures representing the brain are from recent healthy specimens in a per-
fectly natural state, which were prepared and photographed shortly after death, the
tissues being unaltered by chemical reagents.

PLATE 9.
Figure 1,

The right side of the head, with the scalp removed, to show the topographical survey of the
skull in its relations to the brain. The temporal muscle and its fascia have also been
removed, to show their ridges.

Figure 2.

The right side of the head, with the skull removed, showing the dura mater and the main
branches of the great meningeal artery. This also illustrates the contiguous relations of
the tissues of the scalp to the tables of the skull in their surgical application, and especially
to the operation of trephining.

PLATE 10.
Figure 1.

The dura mater removed, to show the vessels of the pia mater over the cortical surface of the
right hemisphere. (From same head as in Plate 9.)

Figure 2.

The pia mater removed from the right hemisphere to show the surface-markings of the fissures
and convolutions, and a topographical survey of the subdivisions of the motor area of the
opercular region according to the most recent investigations of the centres of function
of the cortical surface of the cerebrum. (From same head as in Figure 1.)

N.B.—The figures on Plates 9 and 10 were taken in succession trom the head of an adult male
in remarkable physical health, and represent the structures in their normal condition
and position. Comparison of the series will demonstrate the perplexities attending the
study of cerebral localization, and the parts to be encountered in cerebral surgery.

PLATE 11.

Figure 1.

Transverse (coronal) section through the head just in front of the ears, passing through the
basilar part of the occipital bone below and the bregma above, showing the section of ‘he
brain, in situ, at the middle of the lateral ventricles. (The figure represents the parts as
seen from before.)

Figure 2.

Horizontal section of the head, with the brain in position, showing the iaterai ventricles ana
adjacent parts.
Figure 3.

Antero-posterior section of the head, with the brain in position, through the middle of ths
right hemisphere. The orbital muscles are seen in relation to the eyeball.

PLATE 12.

Median antero-posterior vertical section through the head, face, and neck of a powerfully«
built man, thirty years of age.
Xvi LIST OF ILLUSTRATIONS TO VOLUME I.

PLATE 18.
Figure 1.

The relations of the great vessels and nerves at the base of the skull to the posterior wall
of the pharynx. :
Figure 2.
The face laid open on the left side, to show the relations of the salivary glands and the vessels
and nerves to the tongue. 2
Figure 3.
The posterior wall of the pharynx opened, to show the larynx and the relations of the palate
and tonsils from behind. P
Figure 4.

The lower jaw removed, to show the palate, the tonsils, the fauces, and the tongue extended.

PLATE 14.

Figure 1.

Transverse section of the neck of a negro (male), aged thirty years, from the fifth cervical
vertebra behind to the cricoid cartilage in front.

Figure 2.

Transverse section at the root of the neck (same as Figure 1) on a level with the first dorsal
vertebra.

N.B.—These sections were made on a recent well-developed cadaver, placed in the horizontal
position, without any freezing or hardening agent, and the plates represent the relations
of the parts absolutely as they were.

PLATE 165.

Anterior view of the muscles of the face of a well-developed man, aged thirty-five years,
showing the delicate interlacing of the fibres about.the corners of the eyelids and mouth.
This dissection was made with especial care to demonstrate the anatomy of expression in
its application to the facial markings now considered characteristic of disorders pertaining
to mental, nervous, digestive, and respiratory functions.

N.B.—The platysma muscles have been removed from their attachment at the outer corners
of the mouth, where they form the laughing muscles of Santorini. The vessels and nerves
have also been removed, as they are shown in other plates, in order to give a clearer idea
of the interdependence of the facial muscles.

PLATE 16.

Dissection of the superficial muscles of the right side of the head, face, neck, thorax, and
arm. (From a well-developed male, aged thirty-five years.) The superficial lymphatic
glands and vessels of the face and neck are drawn on the photograph (after notes of many
dissections), to show their arrangement and position.

PLATE 17.

The skin removed on the left side of the neck, to show the platysma myoides muscle and the
usual position of the great external jugular vein. :

PLATE 18.
The superficial fascia removed from the left side of the face, together with the platysma
myoides muscle from the neck, to show the superficial vessels and nerves in these regions,
and especially the superficial relations of the parotid gland.
LIST OF ILLUSTRATIONS TO VOLUME I. xvii

PLATE 19.
The parotid gland removed from the left side of the face, to show the branches of the facial
nerve, and the fascia removed from the posterior cervical triangle, to show more clearly
the superficial cervical plexus of nerves.

PLATE 20,

Dissection of the vessels and nerves of the scalp and face on the left side, and the sterno-
mastoid muscle removed from its sternal and clavicular attachments, to display the deep
cervical plexus of nerves. The fascial slip to the centre of the omo-hyoid muscle is also
removed, to show the relations of the common carotid artery and the internal jugular vein.

PLATE 21.

Deep dissection of the head and neck on the right side, to show the temporal muscle un-
covered by its fascia, and the relative positions of the deep cervical and the brachial
plexuses of nerves.

PLATE 22.
Figure 1. ,

Dissection of the back of the neck, to show the superficial muscles and the nerves and arteries

in the occipital triangles. ,
ee eee Figure 2.

The deep parotid region. The malar bone and ramus of the lower maxillary bone have been
removed, to show the parts beneath, involving the internal maxillary artery (or deep

facial artery).
PLATE 23.
Figure 1.

The skin removed from the anterior region of the neck, to show the platysma myoides muscle

and the superficial cervical veins. Figure 2.

The anterior cervical muscles in relation to the veins, arteries, and nerves. The median raphé
has been cut through, and the anterior thyroid muscles separated, to display the vessels
over the larynx and trachea.

PLATE 24.
Figure 1.
The anterior region of the neck. The sterno-thyroid and sterno-hyoid muscles are removed,
to show the thyroid body in position. (Same as Plate 23.)
Figure 2.

The anterior region of the neck. The isthmus of the thyroid body is divided, and the two
lobes drawn to either side, to expose the depth of the trachea at the root of the neck, and
its relation to the deep transverse thyroid veins. (Same as Plate 23.)

N.B.—The dissections represented in Plates 23 and 24 were made upon a thick, short-necked,
well-developed male subject, aged thirty-five years, to demonstrate the parts especially
concerned in the operations of laryngotomy and tracheotomy.

PLATE 265.
Figure 1.
Deep dissection of the root of the neck. The thyroid body and omo-hyoid muscle are hooked
aside, to show the vessels and nerves, and the clavicle is detached from the sternum.
Figure 2.
Deep dissection of the root of the neck. (Same as Figure 1, the veins being removed.)
Xvill LIST OF ILLUSTRATIONS TO VOLUME I.

PLATE 26.

Figure 1.

The sternum and costal cartilages removed to show the anterior mediastinum, and par-
ticularly the relations of the pleure to the pericardium.

Figure 2.
Dissection of the vascular system of the foetus (at five months and a half).

N.B.—The injection was introduced by the umbilical vein, and the photograph represents the
actual size. e
Figure 3.
Dissection of a child, three weeks after birth, showing especially the relations of the thymus
gland and the supra-renal capsules.

Figure 4.

Photograph of a preparation (in the author’s cabinet), showing a remarkable disposition of
the heart and independent origins of all the great vessels from the root of the aorta.

N.B.—This specimen was removed from the body of a young man, aged twenty-seven years,
who died from phthisis. There is no arch to the aorta, and the position of the heart,
when discovered, was vertical within the thorax, as shown in the figure. There is only
one auricle and one ventricle. No other abnormality of the arteries was found in the body.

PLATE 27.

Topographical survey of the front of the body of a well-developed adult male, with especial
reference to the accuracy of the relations of the thoracic and abdominal viscera to the
external surface coverings.

PLATE 28.

Front view of a natural (ligamentous) skeleton of a European male, aged thirty-eight years,
showing the landmarks with their relations to the surface covering.

PLATE 29.

The anterior wall of the thorax and upper part of the abdomen removed, to show the relations
of the heart, lungs, diaphragm, liver, stomach, and spleen to the ribs and their sternal
cartilages. The lungs are inflated (as in full inspiration), to indicate the so-called area of
the heart’s dulness. (From a male subject, about forty years old, with normal condition
of the organs.)

N.B.—The subject upon which this dissection was made presented the rare anomaly of a
distinct eighth true rib on either side. This is well shown in the plate.

PLATE 80.
The lungs inflated, so as to demonstrate the approximation of their edges over the heart, as
in full inspiration.
N.B.—This and the succeeding plates (31, 32, and 33) were taken from a male subject, about

thirty-two years of age, who died from choking. The lungs were absolutely healthy.
The pleurze were removed in the dissection. :

PLATE 81.

The relations of the lungs, in moderate distention, to the pericardium, as in ordinary
breathing. Also the great vessels and nerves at the root of the neck. The sternum and
costal cartilages are removed.
LIST OF ILLUSTRATIONS TO VOLUME I. xix

PLATE 82.

The relations of the lungs, partially distended (as in tranquil respiration), to the pericardium.
Also the vessels and nerves at the root of the neck.

PLATE 3833.

The relations of the lungs, when completely collapsed, to the heart. Also the deeper relations
of the vessels and nerves at the root of the neck. The pericardium is removed, and the
ribs sawn through at their middle, to give a better view into the cavity of the thorax.
The clavicles also are removed.

PLATE 84.

Preparation to show the relations of the heart within the pericardium.
N.B.—The ribs are cut away, so as to give an unrestricted view.

PLATE 38365.

Preparation to show the relations of the heart and the great vessels at the root of the neck.
The pericardium is opened and held aside.

PLATE 386.

Dissection of the pneumogastric nerve on the left side, and its relations to the phrenic and
sympathetic nerves. (From a female, aged thirty-seven years.)

PLATE 87.

The posterior mediastinum, exposed on the right side by removing the ribs near their angles
and drawing forward the heart and lungs, to demonstrate the entrance of the vena azygos
major into the superior vena cava, and the distribution of the right pneumogastric and
phrenic nerves.

PLATE 88.

The posterior mediastinum and its contents, as seen on removal of the dorsal vertebree (from
the second to the ninth) with portions of their contiguous ribs. The lungs are expanded,
so as to show their proper relations posteriorly.

PLATE 39.

View of the thoracic organs from behind, the dorsal vertebre (from the second to the tenth)
with portions of their contiguous ribs removed. The lungs are displaced, to show the
relations of the heart.

PLATE 40.

The normal position and relations of the thoracic aorta, seen from behind, the lungs being
removed, to show their roots.
PLATE 41.
Figure 1.

The thorax of a young female, with the second, third, fourth, fifth, and sixth ribs removed on
the left side, and the left lung drawn aside, to show the relations of the root of the lung
and the apex of the heart to the diaphragm.

Figure 2.

Transverse section through the thorax of an adult male, on a level with the lower borders of
the third ribs anteriorly and through the body of the eighth dorsal vertebra posteriorly,
seen from below.
XX LIST OF ILLUSTRATIONS TO VOLUME I.

PLATE 42.

Dissection of the vascular system in a child eight months old, showing the principal arteries
and veins in their proper relations and positions.

PLATE 438.
Figure 1.

The front view of the heart removed from the body, with the roots of the great vessels arising
» from the aorta.
‘ Figure 2.

Section of the right auricle and ventricle, to show the interior of their cavities.

Figure 3.

The posterior view of the heart in relation to the thoracic aorta.

Figure 4.

The posterior walls of the left auricle and ventricle removed, to show the interior of their
cavities.

PLATE 4A.
Figure 1.

Dissection of the anterior thoracic region, showing the superficial fascia and mammary glands
on the left side and the great pectoral muscle on the right. The arms are drawn upward
and outward, to bring the axillary borders into prominence and expose their relations to
the vessels and lymphatic glands; of importance in operations upon the breast. (From
a female, aged twenty-four years.)

Figure 2.

Dissection of the muscles of the shoulder and axilla on the right side. The lymphatic glands
and vessels are superposed upon the photograph (from notes of many observations), to
show their proper relations.

PLATE 45.
Figure 1.

Dissection of the right axillary space and inner side of the arm, to show the relations of the
vessels and nerves.
Figure 2.

Deep dissection of the right axilla and inner side of the arm. The deltoid and pectoralis
major and minor muscles are detached and reflected, to show the intricate relations of
the brachial plexus of nerves to the artery and veins.

PLATE Aé6.
Figure 1,

'

The anterior view of the right elbow and forearm of an adult male, with the superficial fascia
carefully removed, to show the relations of the superficial veins and nerves.

Figure 2.

Deeper dissection of same arm as Figure 1. The bicipital fascia and the superficial flexor
muscles are removed, while most of the superficial veins are retained, to preserve their
relations.

PLATTER A427.
Figure 1.

The radial border of the forearm and elbow, showing the relations of the superficial veins—
the superficial fascia being carefully removed—to the muscles and tendons.
LIST OF ILLUSTRATIONS TO VOLUME T. Xxl
\

Figure 2.

The anterior view of the left elbow, to show particularly the bicipital fascia in relation to the
superficial veins and the deep vessels and nerves. ,

Figure 3.

Dissection of the veins on the back of the hand and forearm, with their relations to the
underlying tendons and nerves. :

PLA a Ba E 48.
Figure 1.
Dissection of the palm of the right hand, showing the superficial layer of the palmar fascia.
Figure 2.

Dissection of the palm of the right hand. The superficial layer of the palmar fascia is hooked
aside, to show the deep layer of the fascia and the superficial palmar arterial arch.

Figure 3.

Dissection of the palm of the right hand, showing the position of the superficial arterial arch
and the relations of its digital branches to the nerves and flexor tendons.

Figure 4.

Dissection of the palm of the right hand. The tendons are cut away, to show the deep palmar
arterial arch and its relations, etc.

PLATE 49.
Figure 1.

Dissection of the muscles of the right forearm and hand in pronation, to show the relations of
the extensor tendons of the thumb to the radial artery.

Figure 2.
Dissection of the muscles and tendons of the back of the right forearm and hand in extension.
Figure 3.

Dissection of the tendons of the back of the left hand, showing the relations of the nerves
and arteries.

PLATE 50.
Figure 1.

The relations of the structures involved in the operation of trephining the skull, as in a case
of cortical epilepsy. The disk of bone has been removed and the pia mater partially
detached, to expose the convolutions on the right hemisphere, supposed to include the
centre of the movements of the hand, and especially of the thumb.

Figure 2.

Amputation at the left shoulder-joint by the oval-flap method (of Larrey), showing the rela-
tions of the parts exactly as they appear after the completion of the operation.

PLATE 51.
Figure 1.

Amputation through the middle of the left arm by the antero-posterior oval-flap method,
showing the proper relations of the vessels and nerves to the humerus, in a well-developed
man, aged forty-eight years.
Xxli LIST OF ILLUSTRATIONS TO VOLUME I.

Figure 2.

Amputation at the left elbow-joint by the antero-posterior fiap method (of Dupuytren),
showing the relations of the severed structures immediately after the completion of the
operation. The olecranon process of the ulna is retained, to preserve the function of
extension of the triceps muscle.

Figure 3.

Amputation through the middle of the left forearm by the antero-posterior oval-flap method,

showing the relations of the severed structures on completion of the operation.

PLATE 52.

Figure 1.

The second phalangeal joint of the middle finger of the left hand laid open by an oval in-
cision, as for the anterior flap of an amputation at this joint, to show the relations of the
bone surfaces and the adjacent vessels.

Figure 2.

The metacarpo-phalangeal joint of the middle finger of the left hand opened, as in the first
stage of an amputation (by the lateral-flap method) of the finger, to show the appearance
of the ends of the bones at this joint. The position of the joint, on the dorsal surface,
before the incisions were made, can be judged by comparison with the adjacent fingers.

Figure 3.

Amputation at the carpo-metacarpal joint of the thumb of the left hand (by the flap method),

showing the relative positions of the structures severed in the operation.
Figure 4.

The wrist-joint of the right hand laid open by an oval incision, as for the dorsal flap in ampu-
tation at this joint, showing especially the appearance of the articulation between the
lower end of the radius and the semilunar and scaphoid bones.

Figure 5.

Vertical section through the articulations at the wrist-joint of the right hand, to show the

synovial membranes and the cancellous structure and arrangement of the carpal bones.
Figure 6.

The lefé elbow-joint laid open posteriorly, as in the process of resection or excision of this
articulation, to show the relations of the opposing bones and the adjacent structures.

PLATE 58.

‘Figure 1.

Topographical survey of the right side of the head, face, and neck, with especial adaptation
to cranio-cerebral study, the localization of the areas of distribution of the sensory nerves,
and spots where electrical stimulation produces reflex contractions of some of the musclesin
these regions. Also the landmarks for the operations of tracheotomy and of laryngotomy.

Figure 2.

The left hand in the position of pronation, showing a topographical survey of the areas of
distribution of the sensory nerves on the back of the hand and fingers, and spots where
elcctrical stimulation produces reflex contraction of some of the muscles.

Figure 3.

The right hand in the position of supination, showing a topographical survey of the areas of

distribution of the sensory nerves on the palm of the hand and anterior surface of the

fingers, and spots where some of the muscles may be caused to contract by electrical stimu-
lation. Also the surface-markings on the palm of the hand in relation to the arterial arches.
REGIONAL ANATOMY.
REGIONAL ANATOMY

IN ITS RELATION TO

MEDICINE AND SURGERY.

THE REGION OF THE HEAD.

The surface-form of the head is always pronounced, because the
prominences and depressions, or landmarks (Plate 1), of the skull are
slightly masked by the overlying soft structures.

The thickness of the skull-cap varies greatly, and can only be con-
jectured from external appearances. The average thickness is five milli-
metres, or one-fifth of an inch; the thickest parts are in the basilar
portions, which are originally developed in cartilage, whereas the bones
composing the vault are formed in membrane. In no other part of the
skeleton is the combination of strength and lightness so beautifully
adapted to its purposes as in the cranium.

The contour of the head itself tends to avert the effect of external
violence received at any point, and the natural eminences and processes
occur where protection to the brain is most needed, while in those parts
where it is less needed the bones are thin and light, so as to serve as
a covering with but little extra weight. :

The hollows or sinuses of the cranial bones are rudimentary at birth,
and remain of small size up to about the ninth year, after which they

gradually increase until puberty, when they undergo great enlargement.
1
2 THE REGION OF THE HEAD.

The bones of the cranium are the frontal, two parietal, occipital,
two temporal, sphenoid, and ethmoid. They are immovably connected
in the adult at their edges by the swtwres, which vary in character
according to their position and adaptation. The frontal bone is originally
developed in two portions, which become joined by the frontal suture
shortly after birth. This suture usually closes rapidly, so that it is
obliterated between the second and sixth years, but occasionally it may
persist to the end of a long life. Continued backward approximately
in the middle line from the root of the nose and along the course of
the frontal suture to the occipital bone is the interparietal or sagittal
suture, by which the two parietal bones are dovetailed together. The
parietal bones are connected with the frontal bone by the coronal
suture, and with the occipital by the lambdoid suture. The coronal
suture is more deeply indented laterally than above, and the lambdoid
is remarkable for the tortuous course of its deep dentations. The junc-
tion of the coronal and sagittal sutures, the bregma, may be ascertained
on the living head by drawing upward from the external auditory
openings two lines, which will meet over this point on the top of the
head when it is held in the erect position.

The point of junction of the lambdoid and sagittal sutures, the
lambda, is in the middle line, one-third of the distance from the
external occipital protuberance to the bregma. The lambdoid suture
may be represented by a line drawn from the lambda to the apex of
the mastoid process on each side. The coronal suture corresponds to
a line drawn from the bregma to the middle of the zygomatic arch.
The point where the anterior inferior angle of the parietal bone is
joined to the great wing of the sphenoid bone is the pterion, and is
three centimetres, or about an inch and a quarter, behind the external
angular process of the orbit. At the sides, the arches of the skull are
maintained by the thin scaly margins of the temporal bones overlapping
the bevelled lower edges of the parietal bones, forming the sqgwamous
sutures. The top of each squamous suture is five centimetres, or about
two inches, above the zygoma in the adult head.

The dentate sutures are formed by serrations mainly from the outer
THE REGION OF THE HEAD. 3

table of the bones of the vertex interlocking. They gradually dis-
appear after the fortieth year, the cranial bones becoming fused together
in old age (synosteosis), when they, like the rest of the skeleton, become
‘more porous and brittle and are in consequence more readily fractured.

The closure of the cranial sutures usually begins on the inside of
the vault, but there is great variability as to the time and order in
which it takes place.

The age of an individual cannot be determined from the state of
the cranial sutures. They sometimes disappear at an early age. The
author has several specimens where not a sign of the coronal, sagittal,
or' lambdoid sutures remains at the ages of thirty-three and thirty-seven
years.

At birth all the tabular bones are soft and yielding and capable of
overlapping one another, thereby facilitating the delivery of the head of
the child. In the subsequent growth of the bones the compact layers
are produced, forming the outer and inner tables, with an intervening
cancellated’ structure, the dzploé. In old persons the diploé is often
absorbed, so that the skull in some places becomes very thin,. and it
should be borne in mind that the plane of the inner table is not always
equidistant from that of the outer, a matter of no little moment in
applying the trephine.

The limiting membranes of the vertex bones are united at the lines
of the sutures, and until ossification is completed there are interspaces
at the angles of the parietal bones, known as the fontanelles. These
usually close in shortly after birth, with the exception of the anterior
fontanelle, which occupies the bregma and does not disappear until the
end of the second year. Until this is completely closed by ossific
matter, there is a depression in this locality, through which there is a
regular pulsation perceptible, due to the action of the arteries of the
brain. Persistence of the anterior fontanelle is generally indicative of
hydrocephalus.

Occasionally congenital fissures occur before the normal approxima-
tion of the skull bones is completed. They most commonly occupy the
occipital region, and when they persist in the position of the lambdoid
PLATE lI.

The landmarks of the skeleton of the regions of the head, face, and neck, on the right side, with their relations to

the surface coverings.

1. The point of junction of the coronal and sagittal su-
tures (the bregma).
2. The temporal ridge, for the temporal fascia.
3. The parietal foramen (the obelion).
4, The parietal eminence.
5. The squamous suture. .
6. The point of junction of the lambdoid and sagittal su-
tures (the lambda). :
7. The great wing of the sphenoid bone (the pterion).
8. The external auditory meatus.
9. The mastoid foramen (the asterion).
10. The external occipital protuberance (the inion).
11. The mastoid process of the temporal bone.
‘12. The spine of the second cervical vertebra.
18. The spine of the fifth cervical vertebra.
14. The transverse process of the sixth cervical vertebra,
with first foramen for the vertebral artery.
15. The spine of the seventh cervical vertebra (the vertebra
prominens).
16. The first rib.
17. The spine of the second dorsal vertebra.
18, The frontal eminence.

 

19, The anterior inferior angle of the parietal bone.

20, The supra-orbital foramen.

21. The superciliary ridge (the ophryon).

22. The glabella.

23. The external angular process.

24. The junction of the frontal and nasal bones (the
nasion).

25, The zygomatic arch.

26. The infra-orbital foramen.

27. The second upper molar tooth.

28, The angle of the lower jaw (the gonion).

29, The mental foramen.

30. The top of the hyoid bone.

31, The top of the thyroid cartilage.

82, The cricoid cartilage.

83. The second ring of the trachea.

34, The acromial end of the clavicle.

35. The acromion process of the scapula.

36. The top of the sternum (the manubrium).

37, The coracoid process of the scapula.

88. The glenoid fossa of the scapula.

N. B.—This plate was taken from the skeleton of a well-developed European male, aged about thirty-seven years.
Plate | Von I

 

 

Copyright /89/by GeorseMc Cue anMD

Dissected, Photographed and Colored from Nature ay Georce Mc, Crec.an, MD. Atmetrarseca lees

 
THE REGION OF THE HEAD. 5

sutures they may be mistaken for fractures. In this locality also are
frequently found isolated triangular bony pieces (Wormian bones),
originating from accessory centres of ossification (Plate 3, Fig. 3, Nos.
4 and 13). Supernumerary bones are also often found in hydrocephalic
skulls.

The superciliary ridges are the prominences which support the eye-
brows. They indicate in a measure the size of the frontal sinuses
within the bone, which are first formed by absorption of the spongy
substance (diploé) at the inner angular processes of the orbits, and
gradually spread upward and outward.

The dimensions of the frontal sinuses (Plate 12, No. 25) cannot
always be foretold by the external conformation of the ridges; and they
often appear to be formed by a retrocession of the inner table, especially
in elderly people. They reach a greater degree of development in the
male than in the female. They are usually unsymmetrical, the larger
being on the side from which the nasal septum is bent.

The frontal sinuses connect with the anterior ethmoidal cells and the
middle meatus of the nose by a curved canal called the infundibulum
(page 113). The intervening point between the two superciliary ridges is
called the ophryon. Above the ridges are the frontal eminences (Plate
2, No. 4, and Plate 28, No. 35), indicating the centres of primary ossi-
fication of the original two halves of the frontal bone of infancy, and
corresponding in a measure to the development of the anterior lobes of
the cerebral hemispheres. The glabella is the smooth area between the
superciliary ridges above the nose. Just below it is the point of
junction of the nasal bones with the frontal spine,—the naszon.

The external angular processes of the orbits are the outer limits of
the superciliary ridges. The glabella and the angular processes are
subcutaneous, the ridges being covered by the superciliary muscles and
integument (Plate 1). The supraorbital foramen or notch is on the
border of the orbital arch, just below the superciliary ridge, two and a
half centimetres, or about an inch, from the external angular process.

The temporal ridge, for the attachment of the temporal fascia, starts
from the external angular process and arches backward, usually mid-
6 THE REGION OF THE HEAD.

way between the squamous and sagittal sutures. The temporal muscle
is attached one centimetre, or about half an inch, below the attachment
of the temporal fascia, and sometimes a second distinct ridge is
noticeable on thé cranium. The point of intersection of the upper
temporal ridge with the coronal suture is the stephanion.

The parietal foramina are approximately midway between the bregma
and the external occipital protuberance. They are very near the middle
line, and the area of the brain-case in their locality is often flattened.
This area is called the obelion. The parietal eminences are the points
where ossification first began in the parietal bones. They are very
noticeable, and correspond to the development of the lateral lobes of the
cerebrum.

The external occipital protuberance, the imion, is on a line drawn
horizontally backward from the sockets of the incisor teeth of the upper
jaw. This process is the thickest part of the cranium, but is not always
so prominent that it can be detected through the scalp. From it on
each side the superior curved line arches outward toward the mastoid
process. The mastoid processes are hardly noticeable during childhood.
There is a continuous formation of new bone from the periosteum on
the surface between infancy and puberty, and during this period the
process consists of cancellous tissue which can be readily penetrated by
the knife in mastoid disease. At puberty this cancellous tissue becomes
hollowed by absorption into air-cells, and a larger cavity, the mastoid
antrum, all of which communicate with one another and are connected
with the tympanum. The antrum is separated from the cranial cavity
by only a thin roof of bone (Plate 3, Fig. 5, No. 1). The cells vary
in size in different bodies, and on the two sides of the same head. The
proximity of the lateral sinus renders it liable to become involved by
extension of inflammation in suppurative disease of the mastoid cells,
especially in the adult.

The mastoid foramen is situated near the junction of. the mastoid
portion of the temporal bone and the occipital. It is the largest of
several foramina in this locality, and transmits a vein to the lateral
sinus, and sometimes a small artery to the dura mater.
THE REGION OF THE HEAD. iD

The petrous portions of the temporal bones are hard and dense upon
their surfaces, but, as they are hollowed within for the lodgement of the
structures composing the middle and the internal ear, they are liable to
fracture.. The skull is not inherently strong at its base, and although
undoubtedly fractures do occur in this region by transmitted force from
blows upon the vertex, yet fracture by contre-coup is not now admitted
to be so probable as it was formerly thought to be.

The discharge of cerebro-spinal fluid from the ear, which is one of
the diagnostic signs of fracture at the base of the skull, indicates that
the internal auditory meatus must have been fractured and that a commu-
nication has been established between the tympanum and the internal ear.

Sometimes a serous discharge from the ear follows injury to the
head, where fracture has not taken place: this is due to escape of fluid
from the mastoid cells through a rupture in the tympanic membrane.

Injuries involving the base of the skull must of necessity be serious,
as in this region the cavity of the skull is in relation with the nasal
cavity, the orbit, the frontal sinuses, the sphenoidal sinus, the tympanic
cavity, the upper part of the pharynx, and the spinal cord. Besides
these there are the foramina which give exit to the cranial nerves
(Plate 3, Figs. 1 and 5; Plate 4, Fig. 2; Plate 5, Fig. 2; Plate 11,
Figs. 1 and 3; Plate 12; and Plate 13).

The skin covering the head, which constitutes the scalp, is peculiarly
constructed for the growth of the hair and for protection to the vault
of ,the cranium. It is thicker than in any other part of the body, and
is closely connected by means of the subcutaneous tissue with the aponeu-
roses of the occipito-frontales muscles, so that it moves freely with their
contraction. This mobility is very noticeable in infancy. The readiness
with which the whole thickness of the scalp gives way in contused
wounds is due to the intimate connection between the skin and the
subjacent textures.

The subcutaneous tissue here consists of a dense fibrous structure
enclosing fat lobules (Plates 9 and 12), and resembles that of the palm
of the hand. This continues with the superficial fascia over the muscles
at the back of the neck, and at the sides passes over the temporal fascia.
8 THE REGION OF THE HEAD.

The vessels, nerves, hair-bulbs, and sebaceous glands are contained within
the meshes of this subcutaneous tissue.

The scalp hairs mostly diverge from the obelion. They vary in
character according to their color, length, and diameter, and the manner
in which the hair-follicles are set in the skin, being straight, wavy, curly,
or woolly, according to the straight or the curved axis of each follicle.
Fair hairs are finer and more delicate than dark hairs, and are usually
more closely set in the scalp.

The arteries of the scalp are the terminal branches of the tem-
poral, supra-orbital, frontal, posterior auricular, and occipital. They pass
toward the vertex of the head, running in a tortuous course from their
origins. The ¢emporal artery is the continuation of the external carotid
artery after it has tunnelled through the upper part of the parotid gland
(Plate 18, No. 37). It is six millimetres, or a quarter of an inch, in
front of the ear, and is accompanied by the temporal vein and the
auriculo-temporal nerve. It divides into the anterior and middle tem-
poral branches, which run immediately under the skin (Plate 17, No. 1),
and may serve to indicate the pulse to the physician. The supra-
orbital artery ascends with the supra-orbital nerve (Plate 18, No. 1) from
the supra-orbital notch, or foramen, which is situated two and a half
centimetres, or about an inch, from the outer orbital angle, toward the
nose on the border of the orbital arch. The frontal artery and supra-
trochlear nerve (Plate 19, No. 1) pass upward between the supra-orbital
notch and the root of the nose.

The supra-orbital and frontal arteries come from the ophthalmic artery
within the orbit. The posterior auricular artery and the occipital (Plate
20, Nos. 45 and 50) are branches of the external carotid artery. The
former passes with the posterior auricular nerve in a groove behind the
mastoid process of the temporal bone, and the occipital artery, accompanied
by the great occipital nerve, reaches the scalp at a point midway between
the external occipital protuberance and the mastoid process. The anterior
branch of the temporal artery often becomes very tortuous in the aged,
and sometimes undergoes calcareous degeneration.

Owing to the toughness of the scalp in which the arteries ramify, they
THE REGION OF THE HEAD. 2

cannot be drawn out, and do not retract when divided, as they do else-
where, and hence incised wounds in this region are frequently attended
with troublesome hemorrhage.

The veins of the scalp are quite large, and in a measure accom-
pany the arteries, receiving similar names in their different localities, but
their course is more direct and they freely anastomose. There are two
frontal veins, which generally run parallel at the middle of the fore-
head, sometimes being very prominent in life, and are united at the root
of the nose by a transverse trunk called the nasal arch. Thence they
branch into the angular veins of the face, being joined by the supra-
orbital veins. At this point they receive branches from the superior
ophthalmic veins and establish direct communication with the cavernous
sinuses at the base of the brain. Sometimes there is only one temporal
vein.

The temporal veins commence by anastomosing plexuses on the top
of the head which form into anterior and posterior branches, and unite
into main trunks in close relation to the temporal arteries at the zygoma,
where they receive the blood from the middle temporal veins coming from
the substance of the temporal muscles. The posterior auricular veins
descend behind the ear, receiving the stylo-mastoid veins, and empty into
the temporo-maxillary veins. The occipital veins follow the course of the
occipital arteries, passing beneath the deep muscles at the back of the
neck and terminating usually in the internal jugular veins. At the
mastoid portion of the temporal bone the mastoid vein enters the occipital
or the posterior auricular, thus communicating with the lateral sinus.
This is the largest and most constant of the so-called emissary veins,
which connect the extra- and the intra-venous circulation. Besides the
intercommunication by the ophthalmic and angular veins and the mas-
toid and occipital veins, there are many others which are less constant,
but of equal importance when they do occur. The parietal foramina are
at the vertex in the vicinity of the median line, where the interlocking
of the serrated edges of the parietal bones forms the sagittal suture, and
transmit veins from the scalp to the longitudinal sinus. There is

generally a vein connecting the lateral sinus with the deep veins at the
2
10 THE REGION OF THE HEAD.

back of the neck through the posterior condyloid foramen, on one side or
the other; and there are many apertures at the base of the skull through
which veins pass connecting the cavernous sinuses with the venous plex-
uses of the pharynx and the internal jugular veins. A similar connection
exists more often than is supposed between the veins of the nasal fosse
and the front part of the longitudinal sinus through the foramen cecum,
which in such cases is not closed. There are also minute veins which
connect the diploic veins (Plate 3, Fig. 4) within the tabular bones of
the skull with the veins of the scalp. The emissary veins are well
worthy the attention of the physician or surgeon, for through their
various channels inflammation often spreads from the surface to the
interior of the head, or the reverse; as is witnessed where erysipelas of
the scalp induces meningitis, or in external abscess following injury to
a sinus by a fracture or the application of the trephine.

The lymphatic vessels of the scalp are in relation to the prin-
cipal veins. The frontal lymphatics descend from the forehead and
eyebrows, some going to the lymphatics of the face and ending in the
submaxillary lymphatic glands, while the greater number converge
toward the front of the ear, where they enter the lymphatic glands of the
parotid region (Plate 16, No. 15). The parietal lymphatics pass to the
mastoid glands, are four or five in number, and lie about the insertion
of the sterno-mastoid muscle. The occipital lymphatics go partly to the
sub-occipital glands in front of the occipital attachment of the trapezius
muscle, and partly to the deep cervical glands beneath the sterno-mastoid
muscle at the middle of the neck. The frontal, parietal, and occipital
lymphatic vessels all communicate with one another.

The nerves of the scalp have been considered in their relations with
the arteries. It will be noticed that they also pass toward the vertex
of the head.

In front are the supra-orbital and supra-trochlear branches of the
ophthalmic division of the fifth cranial nerve,—the ¢rifacial (Plate 8,
Fig. 2). They give sensation to the integument over the top of the
head and forehead (Plate 53, Fig. 1, Nos. 1 and 18). |

The supra-orbital nerve is often the seat of frontal neuralgia, which
THE REGION OF THE HEAD. 11

2
probably depends much upon whether the nerve issues from a distinct
bony foramen or only from a notch. In the temporal region are the
filaments from the orbital branch of the superior maxillary division, and
the awricwlo-temporal nerve from the inferior maxillary division, of the
fifth nerve (Plate 19, No. 20). All of these supply sensation. The motor
nerves are derived from the temporal branches of the facial nerve, which
pass upward from among the lobules of the parotid gland to the anterior
portion of the occipito-frontalis, corrugator, supra-auricular, and anterior
auricular muscles. Behind are the posterior auricular branch of the
facial nerve, giving motion to the posterior portion of the occipito-
frontalis and posterior auricular muscles, and the small and great occipital
nerves (Plate 22, Fig. 1, Nos. 3 and 8), the former a branch of the an-
terior division and the latter a branch of the posterior division of the
second cervical nerve. These last are the sensory nerves to the skin over
the back of the head. The auricular branch of the pneumogastric nerve
(Arnold’s) emerges from the auricular fissure just behind the concha
of the ear, which it supplies. The nerves of the scalp communicate fre-
quently with one another.

The cutaneous muscle of the scalp, the occipito-frontalis, con-
sists of two fleshy portions, the frontal and the occipital, united by a
broad aponeurosis, which is continuous with the aponeurosis of the
opposite muscle across the vertex and forms the galea capitis (Plate 16,
No. 1). In bald persons the frontal muscles often plainly show in out-
line on the sides of the forehead.

The frontal portion is a thin layer of pale fleshy fibres extending

upward five centimetres, or about two inches, on the side of the forehead,
" where it joins the aponeurosis. In the middle line, at the nasion, the
fibres blend with those of the fellow muscle, sending a slip downward
to intersect with the pyramidal nasal muscle. The middle and outer
fibres commingle with those of the orbicular and corrugator muscles at
the eyebrows. Some of the innermost fibres are attached to the nasal
bones, some of. the outer to the external angular process of the orbit
(Plate 15, No. 3). The occipital portion is of a darker color than the
frontal. It takes origin by a tendinous insertion on the outer part of
A.

oe co bo

~

1

TAO ew N

wn

PLATE 2.

Figure 1.

Skull showing topographical survey of the relations of the
brain, and the approximate lower level line of the cerebrum.

sutures and eminences to the principal fissures of the

The bregma, the junction of the coronal and sagittal 9. The nasion, the junction of the nasal and frontal bones.
sutures, 10. The external angular process of the orbit.
. The superior frontal sulcus. 11. The fissure of Rolando.
. The posterior frontal or vertical sulcus. 12. The inter-parietal sulcus.
. The frontal eminence. 13. The parietal eminence.
. The superior stephanion, or intersection of the ridge for | 14. The squamo-parietal suture in relation to the horizontal
the temporal fascia with the coronal suture, in its branch of the fissure of Sylvius.
relation to the inferior frontal sulcus. 15. The line indicating the posterior limit of the optic
. The line indicating the anterior limit of the corpus stri- | thalamus.
atum. 16, The upper temporo-sphenoidal sulcus.
. The glabelia (or ophryon). 17. The external parieto-occipital fissure.
. The pterion, the junction of the great wing of thesphenoid | 18. The lambda, the junction of the lambdoid and sagittal
bone with the frontal, parietal, and temporal bones, sutures,
indicating the position of the ascending branch of 19. The lower temporo-sphenoidal sulcus.
the fissure of Sylvius in its relation to the corona! | 20. The inion, the external occipital protuberance.
suture.
Figure 2.

The left side of skull with the parietal bone removed, showing the subjacent convolutions of the left cerebral hemi-
sphere (stripped of their membranes), with topographical survey of the motor area of the opercular region thus exposed.

. The centre for the movements of the face (the expres-
sions).

. The centre for the movements of the lips, tongue, throat,
and larynx.

. The speech centre.

. The pre-central, or posterior, frontal sulcus.

. The ascending frontal convolution.

. The ascending branch of the fissure of Sylvius.

. The centre for the movements of the fingers.

. The centre for the movements of the thumb.

. The centre for the movements of the wrist.
. The centre for the movements of the shoulder and

elbow.

. The centre for the movements of the hip, knee, and leg.
. The centre for the movements of the foot and toes.

. The fissure of Rolando.

. The ascending parietal convolution.

. The horizontal branch of the fissure of Sylvius.

. The external parieto-occipital fissure.

. The cerebellum,
 

Plate 2 Von I

 

AQ

 

Cgpynght/89/ by Georcelc Cue AnD.

Dissected, Photographed and Colored trom Nature by Georce Mc. CLectan, MD, Armstrong & Co Lith Boston

 
THE REGION OF THE HEAD. 13

the upper curved line of the occipital bone and the mastoid portion of
the temporal bone, and, immediately becoming muscular, its parallel fibres
extend upward three centimetres, or about an inch, and then join the
aponeurosis. The aponeurosis of the scalp is continuous across the top of
the head, and is more characteristic behind, where there is a median
area chiefly composed of longitudinal fibres which are attached to the
external occipital protuberance and adjoining portions of the upper
curved line. It is thinner in front, and at the sides, in the temporal
region, it is not so closely associated with the scalp, being continued
over the subjacent temporal fascia as far as the zygoma. Between the
aponeurosis (epicraniwm) and the delicate membrane overlying the skull
bones (pericranium) there is a layer of loose connective tissue, upon
which the mobility of the scalp depends. This mobility is readily seen
in the raising of the brows by contraction of the frontal muscles, in
many of the ordinary facial expressions, and the laxity of the connective
tissue is demonstrated in extensive scalp wounds, where a large flap may
be peeled off from the skull. Incised wounds gape most when they
occur across the direction of the fibres of the muscle. The attachments
of the occipito-frontales muscles, above described, constitute a limited
area of surgical significance in case of wounds and inflammatory affec-
tions attended with suppuration in this region. This area is roughly
indicated by a line drawn round the head from the superciliary ridges”
above the zygoma to the occipital protuberance. The pericranium is
very thin in the adult, and exercises only a protective influence over the
skull bones, playing no part in their nourishment. It is unlike the
periosteum elsewhere, being destitute of its bone-producing properties,
the bones of the cranium receiving their nutrition from the vessels of
the dura mater.

The pericranium may be regarded as the remains of the outer layer
of the developing membrane which surrounded the bones in early life.
It is very slightly attached, except at the sutures, where, in the young,
it blends with the membrane between the soft and growing bones. In
the latter instance sometimes extravasations occur, due generally to
pressure on the head at birth, which are limited to one bone, commonly
14 THE REGION OF THE HEAD.

the parietal. In the temporal region the pericranium is more adherent
to the bone than anywhere else.

- The temporal region corresponds with the temporal muscle, which
occupies the temporal fossa. The skin here is somewhat different from
the scalp proper, having a variable quantity of fat in its subcutaneous
tissue, besides the rudimentary auricular muscles.

The temporal fascia is a bluish-white shining aponeurosis, underlying
the above, of a very unyielding nature, which firmly binds down the
temporal muscle, and sends radiating tendinous slips among the outer
bundles of fibres of the muscle which greatly augment its power. Above
it is attached to the upper temporal ridge on the frontal and parietal
bones, and below it is separated into two leaflets which are inserted into
the outer and inner borders of the zygomatic arch. There is usually a
pad of fat between the muscle and its aponeurosis at the zygoma, the
wasting of which in emaciation and in old age occasions conspicuous
hollows at the temples.

When the temporal muscle is stripped of its fascia, it presents a fan-
shaped appearance (Plate 21, No. 2), with its fibres converging into a
strong tendon, which is inserted into the coronoid process of the lower
jaw at its apex and anterior border. The temporal muscle arises from
the side of the skull one centimetre, or a half-inch, below the attach-
“ment of the fascia. Its deeper surface is in relation to the deep tem-
poral arteries and nerves and to the internal maxillary vessels. Its
motor nerves are derived from the inferior maxillary nerve. The func-
tion of the temporal muscle is to raise the lower jaw forcibly against the
upper. With the masseter (page 122) and pterygoid muscles it is con-
cerned in the mastication of food.

The inequality of the thickness of the skull-cap has already been
mentioned. It depends upon the amount of the diploé between the
outer and inner tables of compact bone. This structure varies consider-
ably, and its amount cannot be determined before a section of the bone
is made. The diploé contains a number of large veins, which occupy
channels in its structure and freely anastomose (Plate 3, Fig. 4) and at
points have extra- and intra~-communications with the veins of the scalp
THE REGION OF THE HEAD. 15

and the sinuses of the dura mater. When the diploé is reached by the
teeth of a trephine saw, the blood from the diploie veins wells up in
a peculiar and distinctive manner.

The inner table of compact bone is thinner and more brittle than
the outer, and is in consequence called the witreous table. Thus its
fracture is accounted for in those cases where it has been broken with-
out the outer table being implicated; and in nearly all cases of com-
plete fracture of the skull bones it is the internal table which is most
broken. The egg-shaped form of the skull has undoubtedly much to do
with the diversion of the effects of violence from the brain, and explains
the possibility of the occurrence of fracture at the base of the skull from
contre-coup.

When the skull-cap is removed its inner surface is found to be grooved
for the branches of the meningeal arteries at the sides, and along the
median line about the attachment of the walls of the superior longitudinal
sinus of the dura mater are depressions for the reception of the so-called
Pacchionian bodies.

The dura mater is the white, dense, fibrous membrane which lines
the interior of the skull, serving the double purpose of being the true
(nutritive) periosteum of the cranial bones and of affording a tough pro~
tective envelope and support to the brain. It is closely adherent over
the whole of the base of the skull, where it is prolonged through the
foramina, becoming continuous with the pericranium and blending with
the fibrous sheaths of the nerves and vessels which pass out of and into
the cranium. Over the vault its attachments are chiefly in the position
of the sutures, where its outer fibrous layer separates to form the venous
sinuses. Elsewhere it is comparatively loose, so that extravasations from
rupture of the meningeal vessels or purulent accumulations may collect
between the dura mater and the bone and cause compression of the brain.
When compression occurs immediately on the receipt of an injury to
the head, it is generally due to a depressed fragment. of bone; but if it
follows after an interval it is probably caused by an extravasation of this
sort. It is worthy of note in this connection that rupture of a vessel of
the dura is usually followed by symptoms of compression more pronounced
16 THE REGION OF THE HEAD.

than when one of the cerebral vessels is involved, owing to the softer
and more yielding nature of the brain-substance. On the other hand,
when a cerebral vessel is ruptured there is little impediment to the
escape of the blood, and often ‘clots of great size are found in the
locality of one of the cerebral vessels. Even in the lines of the sutures
the dura mater can be severed from its bony attachment by taking pains
in the removal of the skull-cap (Plate 4, Fig. 2), and there is little
danger of wounding any of the sinuses with the trephine if the button.
of bone, when it has been cut through by that instrument, is seized with
the forceps and extracted by a gentle rotatory motion. During the growth
of the skull bones in childhood the dura mater is very adherent, and does
not allow extravasations to collect between it and the inner wall of the
cranium.

The Pacchionian bodies, depressions for which are often noticed on the
inner table of the skull-cap, are clusters of whitish granulations of variable
size (Plate 5, Fig. 1). They first appear about the seventh year, and
increase in number as age advances. The localities in which they are
liable to be found are the neighborhood of the great longitudinal sinus,
on the outer surface of the dura, and sometimes within the walls of the
sinus itself. They are also, but rarely, met with in the fissure of Sylvius
and on the margins of the hemispheres. They have been demonstrated
to be hypertrophied villi of the arachnoid membrane, which perforate the
dura mater by pressing outward, and cause the formation of the pits in
the bone by absorption.

The dura mater sends vertical processes between the hemispheres of
the cerebrum and those of the cerebellum, and a transverse arching
partition between the posterior lobes of the cerebrum and the cerebellum
(Plate 4, Fig. 1). The latter is called the tentoriwm, and serves to
prevent the posterior lobes of the cerebrum from pressing upon the
cerebellum. It is attached to the transverse ridges upon the inner sur-
face of the occipital bone, and extends laterally to the superior borders
of the petrous portion of the temporal bones, and forward to the clinoid
processes of the sphenoid bone. The vertical processes are known
respectively as the falx cerebri and the falx cerebelli. The falx cerebri
THE REGION OF THE HEAD. 17

is received into the longitudinal fissure between the two cerebral hemi-
spheres. It is attached in front to the crista galli of the ethmoid bone
by a sharp point, and gradually becomes broader as it arches backward,
assuming the characteristic shape of the blade of a sickle. At its back
part it is connected with the upper surface of the tentorium. The falx
cerebelli is projected into the notch between the hemispheres of the cere-
bellum and extends to the sides of the foramen magnum.

The arteries of the dura mater are very numerous, but the one of
chief importance is the great or middle meningeal artery (Plate 9, Fig. 2).
This vessel is a branch of the internal maxillary artery, and enters
the skull at the foramen spinosum in the margin of the great wing
of the sphenoid bone where it joins the anterior inferior angle of the
parietal bone, at the middle fossa of the skull. It passes upward over
the side of the dura mater in close connection with its two veins, and
divides into anterior and posterior branches, which are received by grooves
or channels in the inner table of the parietal bone. Very often these
channels become in places distinct bony tunnels, so that removal of a
section of the bone so constructed necessitates the rupture of the embedded
artery. At the lower anterior angle of the parietal bone fracture is very
liable to occur, because the bone is peculiarly thin and weak, and,
although the dura mater is adherent here, in such an injury the vessel
can hardly escape laceration. In almost every case of fracture of the
vault of the skull, attended with extravasation of blood, it is one or
other of the branches of the middle meningeal artery which gives way,
and this may even occur without fracture, owing to the loose attachment
of the dura mater within the vault being separated by the vibration
produced by a blow.

The other arteries which supply the dura mater and the various regions
of the skull are, in the temporal region, the lesser meningeal, which enters
at the foramen ovale coming from the internal maxillary (Plate 22, Fig.
2), and a small twig from the ascending pharyngeal artery, which comes
through the middle lacerated foramen at the base of the skull. Anteriorly
there are meningeal arteries from the ethmoid and internal carotid arteries,

and posteriorly branches from the occipital, ascending pharyngeal, and
: 3
18 THE REGION OF THE HEAD.

vertebral arteries. The first two enter by the jugular foramen, and the
latter by the foramen magnum.

All the veins of the dura mater, with the exception of the two which
accompany the middle meningeal artery on either side, terminate in the
great sinuses. They freely anastomose with the diploic veins. The dura
mater not only affords support to the divisions of the brain-mass, but in
certain places separates into two layers, so as to form canals, or sinuses,
by which the venous blood from the brain and its membranes is conveyed
without interference to the internal jugular veins. .

There are as many as fifteen of these sinuses, but the most important
(from a surgical point of view) are the superior longitudinal and the
lateral (Plate 4, Figs. 1 and 2). The dateral sinuses are the main channels
to which all the other sinuses converge. They often differ in size upon
the two sides of the head. They commence at the internal occipital
protuberance and curve outward and downward and inward to the jugular
foramina, being received in the grooves of the occipital and temporal bones
and included in folds of the tentorium. In their course they receive veins
from the cerebellum and from the occipital diploic veins, and are joined
by the petrosal sinuses. They also communicate with the veins of the
scalp by emissary veins through the mastoid foramina, and sometimes
by the posterior condyloid foramina. It is owing to this intercommu-
nication that many cerebral affections are relieved by counter-irritation,
or the application of leeches, in this region. The superior longitudinal
sinus (Plates 4 and 12) is formed by a separation of the layers of the
falx cerebri in the line of the sagittal suture. It commences at the fora-
men ceecum in front of the crista galli of the ethmoid bone, and passes
backward, gradually becoming larger, until it reaches the internal occipital
protuberance. At this point the sinus deviates, usually to the right side.
It becomes dilated and terminates in the corresponding lateral sinus. The
dilatation has long been known as the ¢orcular Herophili, or confluence of
the sinuses (Plate 4, Fig. 1, No. 12).

A transverse section of the superior longitudinal sinus is found to be
triangular, with the base of the triangle upward against the skull (Plate
11, Fig. 1, No. 1). Its lower angle is bridged across at intervals by
THE REGION OF THE HEAD. 19

slender fibrous cords, called chorde Willis. This sinus receives blood
from numerous veins from the adjacent cancellous structure of the skull-
cap, from several large veins from each hemisphere of the cerebrum, and
through a venous link by means of the parietal foramen from the veins
of the scalp. These veins usually enter the walls of the sinus obliquely,
passing from behind forward (Plate 4, Fig. 1) in a direction contrary to
that of the blood-current in the sinus, probably to prevent regurgitation
of blood into the cerebral veins. Very frequently there is a communica-
tion between the veins of the nasal fosse and the apex of the sinus, and
in some cases of severe epistaxis the sinus has been supposed to be tapped
through such a connection.

The superior longitudinal sinus, from its position, is often subjected to
wounds in fracture of the skull, and less frequently in trephining. The
hemorrhage resulting is by no means so serious as to warrant great alarm,
for there are many recorded cases where such hemorrhage has been easily
controlled by gentle pressure. Observation has led to the supposition that
the blood circulates more slowly in the sinuses than in the ordinary veins ;
and their construction seems to be especially for venous receptacles into
which a reflux of blood can take place without exercising compression
upon the brain-substance. The cavernous sinuses are the only other sinuses
of importance, and that because of their intimate relations with the internal
carotid arteries. Owing to these relations, arterio-venous aneurism some-
times follows injury to the base of the brain. The cavernous sinuses are
truly venous plexuses situated at the sides of the body of the sphenoid
bone, surrounding the carotid arteries. They receive blood from the
anterior inferior cerebral veins, and through the ophthalmic veins from the
orbits. This latter communication may lead to thrombosis of the sinuses
by extension of inflammation from disease within the orbits along the
ophthalmic veins. The cavernous sinuses empty their blood by means of
the upper and lower petrosal sinuses into the lateral sinuses.

The nerves of the dura mater are the recurrent branches of the fourth
and some filaments from the fifth of the cranial nerves. Besides these
there have been demonstrated upon the dura filaments from the ophthalmic
and hypoglossal nerves, as well as some from the sympathetic nerve.
th
1

2,

RwONnE

a

mon

10.
11.
12,

wri

ay

m2 wh

au

1,

1.

2.

3.

PLATE 383.
Figure lI.

The base of the skull seen from within, showing the exits of the cranial nerves.
of the skull is retained, surrounding and forming sheaths for all the nerves which

e brain.

The left olfactory bulb (or first
cranial nerve).

The left optic nerve (or second
cranial nerve).

. The left internal carotid artery.
. The optic chiasm.
. The motor oculi nerve (or third

cranial nerve).

. The trochlearis nerve (or fourth

cranial nerve).

. The trifacial nerve (or fifth cranial

nerve).

. The abducent nerve (or sixth cra-

nial nerve).

The distribution of the branches of

. The supra-orbital nerve.

. The supra-trochlear nerve.

. The infra-trochlear nerve.

. The terminal branches of the

lachrymal nerve.

. The infra-orbital branch of the

superior maxillary nerve.

. Thespheno-palatine (sympathetic)

ganglion (or Meckel’s ganglion).

. The descending palatine nerves.
. The infra-orbital nerve and artery.
. The anterior and posterior dental

nerves and arteries.

The superior buccal nerve.

The inferior buccal nerve.

The inferior dental nerve and
artery.

The posterior view of a European skull (the norma occipitalis). Showing

quetra). Nos. 4 and 13.
The sagittal suture.

. The left parietal foramen.
. The left parietal eminence.
. The left side of the upper portion of

the occipital bone (Wormian).

. The lambdoid suture.
. The left asterion.

The right side of a skull of an
The fronto-parietal veins, which
communicate with the superior
petrosal sinus.

15

 

10.

12,

13.

14,

16.

17,

18.

19.

20.
21,

22.

a

8.
9.
10.
11,

(From a female head, aged twenty-one years.)
9.

The facial nerve (or seventh cra-
nial nerve); and the auditory
nerve (or eighth cranial nerve).

The hypoglossal nerve (or twelfth
cranial nerve). —

ll. The glosso-pharyngeal nerve (or

ninth cranial nerve).

The pneumogastric nerve (or the
tenth cranial nerve).

The spinal accessory nerve (or
eleventh cranial nerve).

The crista galli of the ethmoid
bone.

Figure 2.

the trifacial (or fifth cranial nerve), and t

18.
14,

The mental nerves and artery.
The optic nerve.

. A nasal branch from the infra-

orbital nerve.
The position of the Vidian nerve.
The branches of the inferior max-
illary nerve to the muscles of
mastication.
The ophthalmic nerve (or first di-
vision of the trifacial nerve).
The anterior branch of the tem-
poral artery.

The auriculo-temporal nerve.

The posterior branch of the tem-
poral artery.

The temporal artery.

Figure 3.

The external occipital protuber-
ance (the inion).

The left mastoid process.

The digastric groove.

The obelion.

The right parietal eminence.

Figure 4.

terminate usually in the mastoid
vein.

3. The parieto-occipital veins empty-

ing info the lateral sinus,

Figure 5.

15.
16.

17.
18,

19.

20.
21,
22.

heir

23.
24,
25,
26,
27.
28.
29.

oO

30.

31

32.
33.

34.
35,

12.
13.

14,

15,

16.

 

The dura mater lining the fosse
are left in situ after the removal of

The right frontal fossa.

The olivary process of the sphe-
noid bone.

The right internal carotid artery.

The temporal fossa.

The basilar portion of the occipital
bone, joining that of the sphe-
noid.

The right occipital fossa,

The internal occipital crest.

The internal occipital protuber-
ance.

relation to the arteries of the face.

The middle meningeal artery.

The chorda-tympani nerve.

The internal maxillary artery.

The occipital artery.

The posterior auricular artery.

The facial nerve.

The lingual nerve (or gustatory
nerve).

The chorda tympani nerve, where
it joins with the lingual nerve.

. The infra-maxillary branch of the

facial nerve.
The external carotid artery.
The internal carotid artery.

. The common carotid artery.
. The facial artery.

remarkable Wormian bones (or ossa

The lambda.

The right-side of the upper portion
of the occipital bone (Wormian).

The right asterion.

The right mastoid process,

The occipital crest.

adult male, with the outer table rasped away to show the diploic veins.
2. The external parietal veins, which

4, The frontal veins, which communi-

eate with the supra-orbital veins.

5. The fronto-sphenoidal veins, which

connect with the deep temporal
veins.

Oblique section through the left temporal bone, to show the tympanic cavity and mastoid cells on one side, and on
the other the membrana tympani, the ossicles, and the Eustachian tube.

The position of the squamo-petrosal
suture.

The eminence over the semicircu-
lar canals.

The depression for the Gasserian
ganglion of the fifth cranial
nerve on the apex of the petrous
bone.

4, The internal carotid artery entering

5.

its canal.
The tympanic cavity.

6.

7.

The pyramid for the stapedius
muscle.

The stapes resting on the fenestra
ovalis.

8. The fenestra rotunda.

9.
10.
11.

The aqueduct of Fallopius.

Section through the mastoid cells.

The squamous portion of the tem-
poral bone.

12. The position of the canal of Hu-

guier.

18.

14,

15.

16.
17.
18,
19.

The tensor tympani muscle.

The end of the manubrium of the
malleus.

The osseous portion of the Eusta-
chian tube.

The ineus.

The membrana tympani.

The styloid process.

The mastoid process.
cial

 

Copynght/89/ by Georce)

 

   

© by GeoRcE Mc, CLetLan, M D,
THE REGION OF THE HEAD. 21

The cerebral surface of the dura mater is lined by the delicate
arachnoid membrane (Plate 5, Fig. 1), which in the normal state
facilitates the pulsations of the underlying convolutions, owing to its
property of secreting a serous fluid. The amount of fluid between
the dura and the arachnoid tissue is inconsiderable. It is contained
within the sud-dural space, so called in contradistinction to the sub-
arachnoid space, which is between the arachnoid membrane and the sub-
jacent vascular tissue,—the pia mater. The arachnoid membrane is color-
less and extremely thin over the upper surface of the hemispheres, but
it becomes thicker at the base of the brain in front and behind the pons
Varolii, where it is opaque. At these localities there is always a quantity
of serous fluid which serves to support the overlying brain. The arach-
noid fluid passes into the interior ventricular cavities of the brain by
means of the opening into the fourth ventricle for the choroid tela
(Magendie’s foramen), and thus serves to exert a sustaining pressure
both within and without, thereby preventing the ill effects of concussion,
and enabling one hemisphere to support the weight of the other when
the head rests upon the side. The arachnoid membrane does not unite
with the dura except where the cerebral veins pass to the sinuses or
around the corpora Pacchioni, and it does not accompany the pia mater
into the sulci between the convolutions. The arachnoid or cerebro-spinal
fluid is a limpid liquid with a salty taste and a slightly alkaline re-
action. In cases of fracture of the base of the skull, involving the
petrous portion of the temporal bone, the escape of the cerebro-spinal
fluid through the ear is a diagnostic feature, as previously stated.

The pia mater is a delicate net-work of connective tissue in immediate
relation to the surface of the brain, containing within its meshes the rami-
fications of the cerebral vessels. It closely follows the infolding of the
brain-surface, which constitutes the convolutions, and lines the great fissures
which characterize the development of the organ, and by some of them
is continued into the ventricular cavities. After removal of the dura
mater many large superficial veins will be noted passing between the
layers of the pia mater to empty their blood into the sinuses (Plate 5,
Fig. 1, and Plate 10, Fig. 1). They do not regularly accompany the
22 THE REGION OF THE HEAD.

arteries, and on the surface of the hemispheres they freely communicate
with one another. At the base of the brain the pia mater becomes more
dense and fibrous, investing the cerebral crura, the pons, and the medulla
oblongata. Here the contained arteries divide into groups of long vessels
which penetrate the brain-substance and give rise to the anterior and
posterior perforated spaces.

The arteries of the brain are derived from the two internal carotid
arteries, which enter the base of the skull through the carotid canals in the
temporal bones, and from the two vertebral arteries, which, after ascending
through the foramen magnum, unite to form the basilar artery on the
surface of the pons. These main sources which furnish the blood to
the brain pursue a tortuous course (Plate 3, Fig. 5, and Plate 4, Fig. 2)
before they gain entrance into the calvarium, and immediately after-
ward are disposed in a remarkable inosculation (the circle of Willis)
(Plate 5, Fig. 3), for the purpose of equalizing and moderating the flow
of the blood in the several parts of the brain. The internal carotid artery
is surrounded by the cavernous plexus of veins by the side of the body of
the sphenoid bone, and branches into the ophthalmic, anterior, and middle
cerebral, posterior communicating, and anterior choroid arteries. The
anterior and middle cerebral arteries arise from the internal carotid at
the inner end of the fissure of Sylvius. The former passes to the longi-
tudinal fissure, where it is joined to its fellow from the opposite side by
the anterior communicating artery ; thence the two anterior cerebral arteries
run side by side, supplying the adjacent frontal lobes and corpus callosum.
The middle cerebral is the largest branch of the internal carotid (Plate 5,
Fig. 3, No. 18). After giving off numerous small branches to the anterior
perforated space to go to the corpus striatum, it penetrates deeply into
the fissure of Sylvius, furnishing the anterior and middle lobes of the
hemisphere. The anterior choroid branch of the internal carotid passes,
by means of the slit (the hippocampal fissure) in the middle horn of the
lateral ventricle, to the choroid plexus. The posterior communicating
artery is often of unequal size (Plate 5, Fig. 3) on the two sides, and
passes backward to join the posterior cerebral artery from the basilar,
thus completing the arterial chain at the base of the brain.
THE REGION OF THE HEAD. 23

The branches from the posterior cerebral arteries communicate with
those from the anterior and middle cerebral. Before the vertebral arteries
join to form the basilar they give off small branches in the neighborhood
of the medulla oblongata to the contiguous parts, meningeal and spinal
branches, and the posterior cerebellar artery on each side. The other
cerebellar arteries arise from the basilar. The basilar artery also gives
off transverse twigs (Plate 5, Fig. 3) as it lies in the median groove on
the pons, the auditory artery, accompanying the auditory nerve, being
one of them. The vessels which penetrate into the brain are accompanied
by delicate sheaths from the pia mater, which serve as lymphatic channels,
communicating with the sub-arachnoid and sub-dural spaces, the great
cerebral lymph-spaces.

The chief routes by which the pia mater conveys its capillary meshes
into the brain-cavities are by the transverse fissure, as the choroid tela,
into the lateral and third ventricles, and along the roof of the fourth
ventricle, forming the velum interpositum and choroid plexus.

The free intercommunication from side to side of the arteries at the
base of the brain is most important, as there is no anastomosis between
the arteries of the cortical surface and the arteries of the ganglionic masses.
Softening of the brain probably ensues upon inadequate collateral circula-
tion of these vessels, whether due to a pathological or to a traumatic con-
dition. Recently it has been shown that there are special systems of
nutrient arteries derived from the circle of Willis, the central or ganglionic
and the peripheral or cortical arteries. These systems are independent of
each other, and their terminal arteries (of Cohnheim) do not anastomose.

The most noteworthy group of vessels of the ganglionic system are
the branches from the middle cerebral artery which penetrate the anterior
perforated space to supply the corpus striatum and optic thalamus on each
side. A particular branch, the lenticulo-striate artery, so called because of
its distribution to the lenticular and caudate nuclei, is often the source
of cerebral hemorrhage. The cortical arteries are peculiar in their mode
of origin, being adapted to the immediate supply of blood to the brain-
tissue. They arise directly from the larger arteries in minute branches,
which take a vertical or an oblique course, according to their destination,
24 THE REGION OF THE HEAD.

those on the upper border of a convolution being vertical, and those on
the sides passing obliquely. Those which penetrate the layers of cortical
gray matter to the centrum ovale are the medullary capillaries, and vary
from three to five centimetres, or from one to two inches, in length. These
are the terminal arteries proper. In consequence of the independence
of these cerebral capillary systems, many localized lesions, arising from
emboli obstructing the blood-current, can be recognized and explained
during life. Such a lesion may be limited to an area involving a special
function, especially in the region supplied by the branches of the middle
cerebral artery,—t.e., the motor centres and the faculty of speech.

As elsewhere in the body, the principal vessels are supplied with
sympathetic nerves, and these form in the head intricate plexuses mainly
around the internal carotid arteries at the base of the brain.

After removal of the pia mater, the brain-mass, with its furrows and
convolutions, is exposed directly to view (Plate 10, Fig. 2). If the organ
is retained within the skull, the proper relations which the surface-
markings of the brain bear to the overlying structures can be profitably
studied; and, as the subject of cranio-cerebral topography has now
attained great importance, owing to the recent development of intra-
cranial surgery, it will receive especial attention.

In order that a clearer comprehension of this difficult and complex
region may be obtained, a succinct description of the surface anatomy of
the brain removed from the head will be given before explaining its
application.

The brain (encephalon) is that portion of the central nervous sys-
tem which is contained within the cranium, and consists of the cerebrum,
cerebellum, pons, and medulla oblongata. The cerebrum overlies the other
portions of the brain, occupying the whole of the upper part of the
cranial cavity. Its base rests on the anterior and middle fosse of the
skull, and posteriorly it is separated from the cerebellum by the tentorium,
the arching transverse fold of the dura mater. The cerebellum occupies
the occipital fosse. .The pons (Varolii) rests upon the basilar process
and body of the sphenoid bone, and is connected with the cerebrum by
the crura cerebri, and with the cerebellum by the crura cerebelli. The
THE REGION OF THE HEAD. 25

medulla oblongata is the portion below the pons, and rests upon the basi-
lar process of the occipital bone. It is continuous with the spinal cord.

The brain conforms in size and shape with the interior of the skull, or
brain-case. Its mass is to some extent related to the size of the body, and
it is modified by the degree of mental development of the individual to
whom it belongs, the intelligence probably depending upon the quality
rather than upon the quantity of the organ. During intra-uterine life
the development of the brain is very active, and at birth it is relatiyely
of large size, of a soft pulpy consistence, presenting an approximation in
form and relations to the adult brain. It grows rapidly up to the seventh
year, becoming gradually firmer, and from that period until about the age
of forty it increases very slowly. Its full growth is considered to have been
attained between forty-five and fifty years of age. The average weight
of the brain in males is forty-nine ounces; in females, forty-four ounces.
In old age it decreases in a measure commensurate with the waning of
the faculties. The brain consists of gray and white neural tissue variously
disposed, the gray matter, composed mainly of nerve-cells, being arranged
on the cortical surface, and in the ganglionic masses at the base of the
organ; the white matter, made up of nerve-fibres, being within, and serving
to connect the gray portions and to bring them into relation with the
spinal cord through the pons and medulla. The gray matter on the
cortical surface is arranged in several layers of various forms of cells,
which are intimately surrounded with numberless capillary vessels from
the adjacent pia mater. These cells are connected through their pro-
longations with the nerve-fibres of the white substance. The minute
structure of the nerve-cells and nerve-fibres is described with the anatomy
of the spinal cord in Vol. IL.

The whole brain is partially divided into symmetrical halves by a
median fissure extending from before backward. The area of the surface
of the brain is greatly extended by the cortical gray matter being
irregularly raised in tortuous convolutions (gyri) or involuted into
furrows (sulci), so that, with great economy of space, its actual surface
is nearly six times what it would be were it merely a smooth envelope.

The number of convolutions and the depth of the furrows between them
4
26 THE REGION OF THE HEAD.

vary in different brains, and consequently the extent of the gray surface-
matter upon which the intellectual capacity depends is variable.

All physical and moral actions have their perceptive centres some-
where in the cortical substance of the cerebrum. An animal may live
after removal of its cerebral hemispheres, but it will be insensible to
peripheral disturbance and incapable of exercising volition. The anterior
portions of the hemispheres are without sensibility, as is manifest in
cases of wounds in which they have been injured.

The cerebrum consists chiefly of two lateral masses, called, from their
shape, hemispheres, which are partially separated by the falx cerebri of
the dura mater being received into the great longitudinal fissure between
them. At the bottom of this fissure a band of white transverse nerve-
tissue connects the two hemispheres: this band, owing to the decussation
of its component fibres, is known as the commissure of the cerebrum, or
the corpus callosum (Plate 11, Fig. 1, No. 8).

The hemispheres are not always of equal size, as the longitudinal
fissure is not always placed exactly in the middle line (Plate 6, Fig. 1).
The left hemisphere has generally been found to be larger than the
right, and this has been attributed to the more direct blood-supply to the
brain on that side, through the left vertebral and common carotid arteries,
the latter arising independently from the arch of the aorta. The right
hemisphere is often, however, larger than the left (Plate 6, Fig. 1) in a
brain otherwise normally developed. Each hemisphere consists of an
anterior (frontal), a middle (temporo-sphenoidal), and a posterior (occip-
ital) lobe, which are best seen on the under surface, and correspond to
their respective positions in the fosse of the cranium. Besides these
there are the parietal lobe, placed between the frontal and the occipital
lobe, on the lateral and upper surface, and the central lobe, situated
within the fissure of Sylvius, at the base of the brain.

The disposition of the convolutions and furrows on the surfaces of
the two hemispheres is not identical, owing to the varying development
of the several localities. It is, therefore, improbable that any definite
area will always possess the same group of nerve-cells, for they may be
on the surface of a convolution in one brain, and in an adjacent furrow
THE REGION OF THE HEAD. 27

in another, depending upon the relative growth of the locality. The
primary fissures of the cerebral hemispheres—viz., the Sylvian, hippo-
campal, parieto-occipital, and calcarine—appear during the third month of
foetal life. The secondary fissures, the most important being the fissure
of Rolando, appear between the fifth and sixth months. The further de-
velopment of the fissures, and consequently of the convolutions, occupies
the last two months of fetal life and the first five or six weeks after
birth, at which time the cerebral surface can be clearly mapped out.
The largest and most complicated convolutions characteristic of the human
brain are upon the wpper surface of the hemispheres, frequently branch-
ing toward the longitudinal fissure in their course like the letter Y.
They do not exactly correspond upon the two sides. The most important
of the convolutions on the external surface of the hemispheres are the
central, or parietal, convolutions, which are always the most perfectly
developed in all animals whose brains are convoluted. They occupy
approximately the same relative position on each side of the brain, and
are separated by the deep fissure of Rolando or central fissure (Plates 6
and 7). The area surrounding this fissure has been satisfactorily proved
by physiological research and pathological facts to involve the principal
motor functions of the body (Plate 2, Fig. 2, and Plate 10, Fig. 2).
The fissure of Rolando (Plate 6, Fig. 1, Nos. 3 and 18, and Plate
7, Figs. 1 and 2, No. 1) usually begins close to the longitudinal fissure,
about its middle, on the upper surface, and runs obliquely over the outer
convex surface of the hemisphere downward and forward, until within
a short distance of the fork of the Sylvian fissure. The lesser wing
of the sphenoid bone is lodged within the fissure of Sylvius. This fissure
begins (Plate 6, Fig. 2, No. 6) in a depression called the vadlecula, at the
anterior perforated space at the base of the cerebrum, and passes outward
as a deep cleft (Plate 7, Fig. 1, No. 22), which divides into an ascending
or vertical branch two centimetres, or a little less than an inch, in length,
and a horizontal branch, which passes backward and curves slightly
upward. It usually terminates in the parietal lobe in a bifid extremity.
At the point where these branches originate, a third branch passes trans-
versely, and is hidden within the substance of the brain. The branches
a

i.

s

No

oO ow

10.

11.
12.

13.

14,

16.

SeePnNtanpwnwre

PLATE 4.
Figure 1.

The right hemisphere of the cerebrum removed to show the falx cerebri and tentorium of the dura mater, and the
relations of the great sinuses and their tributaries. (From the same head as in Plates 9 and 10.)

. The cut tissues of the scalp. 11. The tentorium cerebelli.
. The outer table of the skull-cap. 12. The position of the torcular Herophili.
. The diploic structure. 13. One of the anterior tributary veins.
. The inner table of the skull-cap. 14. The convolution of the corpus callosum of the left
. The superior longitudinal sinus. hemisphere,
. The inferior longitudinal sinus. 15. The apex of the longitudinal sinus passing to the fora-
‘Lhe falx cerebri. men cecum. .
. One of the posterior tributary veins. 16. The artery of the corpus callosum.
. The vene Galeni. 17. The crista galli of the ethmoid bone.
. The straight sinus, 18, The corpus callosum.
Figure 2.

The posterior third of the skull and its scalp removed to show the posterior view of the dura mater, and the conflu-
ence of the lateral and occipital sinuses with the superior longitudinal sinus, Also the posterior segments of the cervical
vertebra are removed to show the continuation of the dura mater of the brain with that of the spinal cord, the ganglions
on the posterior roots of the cervical nerves, and the course of the vertebral arteries through the vertebral foramina.

The cut tissues of the scalp.

The section of the parietal bones at the sagittal su-
ture.

The dura mater over the posterior lobe of the left
hemisphere of the cerebrum.

. The great, or superior, longitudinal sinus.
. The posterior branches of the left middle meningeal

artery.

. The left lateral sinus.

The left occipital sinus.

. The left sub-occipital (or first cervical nerve).
. The left vertebral artery curving upon itself before

entering the foramen magnum.

The ganglion on the posterior root of the second cer-
vical nerve. :

The left transverse process of the atlas vertebra.

The descending branch of the posterior division of the
second cervical nerve, passing to the third.

The ganglion on the posterior root of the third cervical
nerve.

The left internal jugular vein.

. The left common carotid artery.

The ganglion on the posterior root of the fourth cervical
nerve.

 

17.
18.

19.
20.

21,
22.
23.
24,
25.
26.

27.
28.
29.
30.

31.
32.
33,
34,
35.
36.

The left sterno-cleido mastoid muscle.

The ganglion on the posterior root of the fifth cervical
nerve,

The left brachial plexus of nerves.

The posterior branches of the right middle meningeal
artery.

The right lateral sinus.

The right occipital sinus.

The right posterior meningeal artery.

The right sub-occipital (or first cervical nerve).

The right vertebral artery at its curvature.

The occipitalis major nerve (or internal branch of the
posterior division of the second cervical nerve).

The right spinal accessory nerve,

The descending branch of the second cervical nerve.

The right common carotid artery.

The ganglion on the posterior root of the third cervical
nerve.

The right internal jugular vein.

The right vertebral artery.

The dura mater of the spinal cord.

The right fourth cervical nerve.

The right fifth cervical nerve.

The right brachial plexus.
Plate 4 | Vou T

 

 

 

Copyrght(82/.by GeorceMeL ett an, M.D.

 

Dissected, Photographed and Colored trom Nature by Georce Mc, CLecean, MD,
THE REGION OF THE HEAD. 29

of the fissure of Sylvius originate from the development of the hemi-
sphere around the central lobe (or insula), which is usually covered in
(Plate 7, Fig. 1), but is occasionally visible (Plate 7, Fig. 2, No. 7).
The portion of the hemisphere overlapping the central lobe is called
the operculum, from its lid-like character. The fissure of Sylvius is
the most conspicuous of the cerebral fissures, and is easily recognizable.
The parieto-occipital fissure is seen on the median surface (Plate 8, Fig. 1,
No. 5, and Fig. 2, No. 20). It begins at the calcarine fissure near the
corpus callosum, and ascends vertically, ending on the external surface,
about an inch beyond the longitudinal fissure. It partially defines the
parietal and occipital lobes, and occasionally blends with the horizontal
branch of the Sylvian fissure. The calearine fissure (Plate 8, Fig. 1,
No. 7, and Fig. 2, No. 23) begins near the posterior border of the hemi-
sphere and passes forward, receiving the parieto-occipital fissure midway,
and ends under the corpus callosum, penetrating into the posterior horn
of the lateral ventricle, dividing the hippocampal convolution.

The hippocampal fissure extends from the gyrus fornicatus to the hip-
pocampal hook. The fascia dentata projects inwardly through this fissure,
over which the pia mater passes to join with the choroid plexus of the
lateral ventricle.

The transverse fissure (of Bichat) is the breach between the cerebrum
and the cerebellum (Plate 7, Fig. 1, No. 12). This fissure is due to the
cerebral hemispheres being folded backward over the thalamic region,
and it admits the pia mater into the interior of the brain as the velum
interpositum.

The interparietal fissure (Plate 7, Fig. 1, No. 5, and Fig. 2, No. 20)
is the most important of the secondary furrows on the parietal portion of
the hemisphere. It is very variable in form and position, sometimes being
connected with the parieto-occipital and sometimes with the horizontal
branch of the Sylvian fissure. Generally it begins between the latter
and the Rolandian fissure, and curves backward somewhat parallel with
the superior border of the cerebrum.

It will be noticed that the character of nearly all the great fissures
which separate the cortical surface into lobes is variable. This is even
30 THE REGION OF THE HEAD.

more so with regard to the smaller (intra-lobular) fissures between the
convolutions in the different lobes of the hemispheres. The changes in
the position of these furrows probably depend upon the variability of
the development of their localities in different brains.

The frontal lobe (Plate 6, Fig. 1, No. 2) consists of the cerebral
surface situated in front of the fissure of “Rolando and over the fissure
of Sylvius. This lobe is divided by furrows (the frontal sulci) into four
principal convolutions (the frontal gyri), which are subdivided into sec-
ondary convolutions by modifications of their arrangement and connections.
The frontal convolutions are the superior, middle, and inferior, and the
anterior central (Plate 7, Fig. 2, Nos. 2, 3,4, and 5). The superior frontal
convolution (Plate 7, Fig. 1, No. 15) is in relation to the longitudinal
fissure, borders on the anterior part of the corpus callosum internally, and
extends to the under surface, where it is known as the olfactory convolu-
tion, from its reception of the olfactory bulb in a depression (Plate 6,
Fig. 2, No. 2). The adjacent middle frontal convolution (Plate 7, Fig. 1,
No. 17) also extends to the under surface, and is there called the orbital
convolution. The inferior frontal convolution (Plate 7, Fig. 1, No. 19)
is below the preceding and in relation to the Sylvian fissure. It is now
often called Broca’s convolution, or the speech centre, from the localization
of the movements of the lips and tongue, in articulation, in its posterior
portion.

The anterior central or ascending frontal convolution (Plate 7, Fig. 1,
No. 14) is separated from the three frontal convolutions by the posterior
frontal (or vertical) furrow (Plate 7, Fig. 1, No. 16), and it usually blends
with the upper and lower frontal convolutions, and with the posterior
central convolution, curving round the ends of the central fissure of
Rolando.

The parietal lobe occupies the upper and lateral portions of the
hemisphere between the fissure of Rolando and the external part of the
parieto-occipital fissure, and is over the horizontal branch of the fissure
of Sylvius. There are three principal convolutions on the outer surface
of this lobe,—the posterior central and the superior and inferior parietal
convolutions.
THE REGION OF THE HEAD. 31

The posterior central or ascending parietal convolution is, as before
stated, ordinarily continuous with the anterior central or ascending frontal.
The two convolutions thus completely surround the fissure of Rolando
(on the cortical surface), and the area thus formed is called the opercular
lobe (Plates 6 and 7). The connecting portion above the fissure of Rolando
is the para-central lobule, and that below it is the wnfra-central lobule. The
latter region is considered to be correlated with the movements of the head
and face, while those of the arm and hand are referred to the middle por-
tions of the anterior and posterior central convolutions, and those of the
leg and foot to the para-central region.

The superior and inferior parietal convolutions are separated by the
inter-parietal fissure (Plate 7, Fig. 2, No. 20), and are usually continuous
with the convolutions of the occipital lobe by bridges of gray matter called
the annectent convolutions.

Both of the parietal convolutions are variously subdivided. The
imfertor is very tortuous, and commonly consists of two chief portions,
the superior marginal and the angular convolution. The former usually
blends with the lower part of the posterior central convolution and arches
over the end of the horizontal branch of the Sylvian fissure to join the
superior temporal convolution. The angular convolution (Plate 7, Fig. 1,
No. 7) is behind the supra-marginal and parallel with the Sylvian fissure.
It usually joins the middle temporal convolution by means of the two lower
annectent convolutions. Upon the median surface the superior parietal
convolution joins with the upper extremity of the posterior central con-
volution to form the precuneus, or quadrate lobule (Plate 8, Fig. 2, No.
18), which is continuous with the convolution of the corpus callosum.

The occipital lobe, also variously subdivided, presents three principal
convolutions, superior, middle, and inferior, which are subdivided by the
occipital fissures and continuous with the convolutions of the parietal and
temporal lobes. Upon the median surface the superior occipital convolu-
tion, somewhat triangular in shape, forms the cuneus lobule, placed between
the parieto-occipital fissure and the calcarine fissure.

The surface of the occipital lobe which rests upon the tentorium is
composed chiefly of two convolutions, the inner one of which blends with
32 THE REGION OF THE HEAD.

the hippocampal convolution and the outer one is the occipital part of the
occipito-temporal convolution. They are both continuous with the con-
volutions on the under surface of the temporal lobe. The temporal lobe
(temporo-sphenoidal) presents on its outer surface generally three defined
convolutions, superior, middle, and inferior, separated by variously arranged
temporal fissures, and connected, as above stated, with the parietal and
occipital convolutions.

The hippocampal convolution is separated from the occipito-temporal
convolution, on the under surface, by the collateral fissure. It forms
the floor of the middle horn of the lateral ventricle, terminating in the
hippocampal hook (processus unciformis). The calcarine fissure divides
the hippocampal convolution at the back part of the corpus callosum.

The central lobe, island of Reil, or insula, as it is variously known,
is situated within the fork of the Sylvian fissure, where it is occasion-
ally partially visible on the external surface (Plate 7, Fig. 2, No. 7),
and is overlapped by the operculum. It consists of from four to six
small convolutions (the gyri operti), arranged side by side upon a trian-
gular mass, and appearing, when exposed, very much like the fingers of
the hand when closed upon the palm. These convolutions are the first
to appear in the foetus and among animals, and are gradually enclosed
by the other principal convolutions developing around them.

Behind the central lobe there are usually several small convolutions,
known as the ¢emporo-parietal or retro-insular convolutions. They bridge
over the temporal and parietal lobes. The fornicate convolution, or con-
volution of the corpus callosum, which is to be seen on the median surface .
(Plate 8, Fig. 1, No. 16), extends round the upper surface of the corpus
callosum, beginning at the anterior perforated space, and blending behind
with the uncinate convolution below the quadrate lobule.

Cranio-Cerebral Topography.—In the description of the landmarks
of the head the relations which the external parts of the cranium bear
to the surface-coverings are stated in detail. The topographical survey
of the skull is here considered in its relation to the brain (Plate 9,
Fig. 1).

The points on the outer surface of the calvarium which bear upon
THE REGION OF THE HEAD. 33

the position of the principal fissures of the brain cannot always be defi-
nitely determined through the scalp, even though the head be shaved;
and the most careful observation, or calculation based on statistics of
measurements, cannot insure accuracy, for no two heads are precisely
alike in their conformation and the arrangement of their contents.
Only approximative results can be obtained by deducing from the
landmarks of any skull the relative positions of the parts of the brain
which it contains. A line drawn across the forehead above the eye-
brows in front, and along the side of the head, two centimetres, or a
finger’s breadth, above the external angular process of the orbit, to the
root of the zygomatic process and thence to the external occipital protube-
rance, corresponds in a measure to the lower level of the cerebrum (Plate 2,
Fig. 1); the cerebellum occupies the space below the latter portion of this
line, but its lower level cannot be defined externally, as it depends upon
the extent to which the lower occipital fossee project at the nape of the
neck. The frontal and parietal emimences seem to indicate the propor-
tionate development of the frontal and parietal lobes of the cerebrum.
The parietal eminence corresponds to the supra-marginal convolution,
and the frontal eminence to the superior frontal convolution. The péerion
is the junction of the great wing of the sphenoid bone with the frontal,
parietal, and temporal bones. Here the fisswre of Sylvius commences.
Its short ascending branch is just behind and parallel with the coronal
suture, and its long horizontal branch extends upward and backward
across the upper margin of the squamo-parietal suture on a line drawn
on the side of the head from the nasion to the lambda (Plate 2, Fig. 2,
No. 6, and Plate 53, Fig. 1, No. 18). The coronal suture passes from
the bregma, the junction of the coronal and sagittal sutures, at the
top of the head, to the middle of the zygomatic arch. The lambda
is the junction of the sagittal and lambdoid sutures. The external portion
of the parieto-occipital fissure is a little in front of the lambda. The
inion is the external occipital protuberance. The upper end of the
fissure of Rolando (Plate 2, Fig. 2, No. 13) begins at or near the middle
line five centimetres, or about two inches, behind the coronal suture, or at

a point one centimetre, or about half an inch, back from the middle of
5
PLATE 5.
Figure 1.

The pia mater, with its vessels ramifying over the convolutions on the upper surface of the hemispheres, The longi:
tudinal sinus in position, with clusters of the Pacchionian granules within it and upon either side.

1. The frontal sinus of the skull. 5. The vessels of the pia mater over the left hemisphere.
2. The forepart of the longitudinal sinus passing towards | 6. The longitudinal sinus passing backward to the tor-
the foramen cecum. cular Herophili.
3. The Pacchionian granules in relation to the left side of | 7. The Pacchionian granules in relation to the right side of
the longitudinal sinus. the longitudinal sinus.
4. The longitudinal sinus of the dura mater. 8. The vessels of the pia mater over the right hemisphere.
Figure 2.

The base of the skull with the cerebellum retained in the occipital fosse. Portions of the orbital roofs are removed
to show the nerves and muscles passing to the eyeballs.

1. The frontal branch of the left ophthalmic nerve. 14. The left lobe of the cerebellum, showing the superior
2. ‘The left supra-trochlear nerve. cerebellar veins.
8. The left eyeball. 15. The right eyeball.
4. The left superior rectus muscle. 16. The right external rectus muscle.
5, The nasal branch of the left ophthalmic nerve. 17. The frontal branch of the right ophthalmic nerve.
6. The fatty capsule of Tenon. 18, The right superior rectus muscle,
7. The left external rectus muscle. 19. The nasal branch of the right ophthalmic nerve.
8. The left optic nerve, passing into the optic fora- | 20. The capsule of Tenon.
men. 21. The right optic nerve.
9. The left internal carotid artery. 22. The right internal carotid artery.
10. The optic commissure.: 23. The pituitary fossa.
11. The nerve to the left superior oblique muscle (or fourth ; 24. The nerve to the right superior oblique muscle (or
cranial nerve). fourth cranial nerve).
12, The Gasserian ganglion of the left fifth cranial nerve. 25. The Gasserian ganglion of the right fifth cranial nerve.
13. The cut end of the left abducent nerve to the external | 26. Section through the pons Varolii.
rectus muscle, 27, The right lobe of the cerebellum.

 

Figure 3.

The base of the brain, showing the anastomosis of the arteries, called the circle of Willis. (From an adult male.)

1, The arteries of the corpus callosum within the longi- | 16. The arteries to the left frontal Jobe.
tudinal fissure. 17. The left anterior cerebral artery.
2. The arteries to the right frontal convolutions. 18. The middle cerebral artery, within the fissure of Syl-
3. The right anterior cerebral artery. vius, which is displayed by separation of the frontal
4, The right fissure of Sylvius. and parietal lobes.
5. The anterior communicating artery. 19. The cut end of the left internal carotid artery.
6. The optic commissure. 20, The pituitary body (in this case unusually large).
7. The cut end of the right internal carotid artery. 21. The left corpus albicans.
8. The right posterior communicating artery. 22. The left posterior communicating artery.
9. The right posterior cerebral artery. 23. The left posterior cerebral artery.
10. The basilar artery, resting on the median groove of the | 24. The left auditory artery.
pons Varolii. 25. The left posterior cerebellar artery.
11. The right superior cerebellar artery. 26. The left vertebral artery.
12. The right inferior cerebellar artery. 27. The medulla oblongata.
18. The right vertebral artery. 28, The external branches of the left posterior cerebellar
14. The anterior spinal artery. artery. \ :
15. The posterior inferior cerebellar artery.

 
Plate 5 Vou |

 

Copyright, 184, b. Georce Mc Ciecian, M D

Dissecta?, Photographed and Coloreo trom Nature ty Georse Mc. Cretran, MD. ne

trong s Co Litt Boston
THE REGION OF THE HEAD. 35

the distance from the ophryon, or glabella, to the inion. This fissure
passes obliquely downward toward the horizontal branch of the fissure of
Sylvius, and its lower end is two and one-half centimetres, or about one
inch, behind the coronal suture ‘where it joins the other bones to form
the pterion. The posterior frontal sulcus (or furrow) is just behind and
parallel with the coronal suture (Plate 2, Fig. 2, No. 4). It is some-
times called the vertical sulcus. The ascending frontal convolution is
between the posterior frontal sulcus and the fissure of Rolando.

The upper end of the posterior frontal sulcus reaches to about the
middle of the fissure of Rolando. The inferior frontal sulcus branches off
from it about on a level with the superior stephanion, which is the point
of intersection of the coronal suture and the ridge for the temporal fascia
(Plate 2, Fig. 1, No. 5). The superior frontal sulcus begins in the upper
part of the ascending frontal convolution, over the posterior frontal sulcus,
and passes forward and parallel with the inferior. The lower end of the
inferior frontal sulcus is separated from the fissure of Sylvius by the oper-
culum. The inter-parietal sulcus is behind the fissure of Rolando and
parallel with the great longitudinal fissure between the hemispheres. It
is midway between the latter and the parietal eminence (Plate 2, Fig. 1,
No. 12). The dasion is the middle of the anterior border of the foramen
magnum at the base of the skull. 4

The convolutions in the various regions are designated according to
their positions, and their relations are mapped out when the positions of
the fissures and sulci are determined.

In seeking to ascertain the function of any locality on the cerebrum,
it has been discovered, by means of gentle electrical stimulation, that the
so-called motor cells are only in the gray matter on the surface, and that
faradism of the sides and bottom of the fissures produces no motor
reaction.

The area of the opercular lobe, which includes the central fissure of
Rolando, has been demonstrated to be the controlling centre of the move-
ments of the limbs (Plate 2, Fig. 2, and Plate 10, Fig. 2). This area’
consists of the following convolutions: the anterior central (or ascending
frontal) convolution, in front of the central fissure: the posterior central
36 THE REGION OF THE HEAD.

{or ascending parietal) convolution, behind the central fissure; the para-
central convolution, which surmounts the central fissure and extends on the
median surface of the hemisphere to the calloso-marginal fissure (Plate 8,
Fig. 2, No. 17); and the infra-central convolution, which separates the
‘central fissure from the horizontal branch of the fissure of Sylvius. The
infra-central convolution is correlated with the movements of the face
(mouth, lips, tongue, throat, and larynx). Movements of the fingers are
produced by stimulation of the cortical surface in the lower portion of the
anterior central convolution, and movements of the thumb by stimulation
of the corresponding portion of the posterior central convolution. The
centre for the wrist is just above the latter, at about the middle of
the central fissure, and that for the elbow and shoulder a little higher.
Observation has shown that the centres for the upper extremity embrace
the adjacent portions of the convolutions on both sides of the central
fissure (Plate 10, Fig. 2). The movements of the hip, knee, leg, foot,
and toes are presided over by the para-central convolution and the
contiguous parts of the anterior and posterior central convolutions.

The inter-parietal fissure is probably the posterior limit of the motor
area.

The frontal lobe of the brain anterior to the motor region seems to be
related to the~highest processes of the mind. Lesions in this locality are
generally followed by proportionate mental deterioration.

The sensorial area has not been conclusively determined, but it is
believed to include the general surface of the cerebrum posterior to the
inter-parietal fissure, limited externally by the parieto-occipital fissure
(Plate 7 and Plate 10, Fig. 2) and internally by the calloso-marginal
fissure (Plate 8).

The centre for the movements of the eyes and eyelids involves the
angular gyrus; while the centre for vision extends from the angular gyrus
over the occipital lobe and adjoining portions of the temporal and parietal
lobes. The centre for hearing seems to be localized in the first and second
temporo-sphenoidal convolutions. The centre for smell is supposed to be
established in the hook of the hippocampal convolution, and the centre
for taste just below it. The speech-centre has already been mentioned
THE REGION OF THE HEAD. 37

in the description of the inferior frontal convolution (page 30). It is
posterior to the fork of the fissure of Sylvius.

The function of the island of Reil, or central lobe, is not determined,
but, from its development, its position, and its relation to the other lobes
of the brain as well as the, basal ganglia, it probably plays an important
réle in the association of their related functions.

During life the vessels of the pia mater are engorged with blood,
especially if the patient has been under the influence of alcohol or an
anesthetic, and the subjacent cerebral fissures and sulci are indistinguish-
able through an opening in the skull. All that is possible, therefore,
is to conjecture or infer what portion of the cortical surface of the brain
is at the bottom of a hole made by the trephine (Plate 50, Fig. 1).

That the results of operative interference with the brain-structure
should so often verify diagnosis is cause for wonder, when one considers
the uncertain features of the anatomy of localization (Plates 9 and 10).
Repeated examinations of the relations of the fissures to carefully mapped-
out points after removal of a disk of bone on the heads of many cadavers
have shown the author the fallacy of depending solely upon measurements,
and the importance of making the artificial opening in the skull large
enough to enable the operator to see the parts exposed.

The base of the cerebrum is subdivided, as already. described, into
anterior, middle, and posterior lobes for each hemisphere. The posterior
lobes are separated from the cerebellum by the tentorium of the dura
mater.

When the entire brain is removed from the calvarium and its under
surface (Plate 6, Fig. 2) examined, the arrangement of the objects
brought to view can be best studied by commencing in front. The longi-
tudinal fissure, approximately in the middle line, separates the frontal
lobes. Within the longitudinal fissure is the transverse commissure, or
corpus callosum, from which white bands pass backward on each side to
the fissure of Sylvius. They are called the peduncles of the corpus cal-
losum. The lamina cinerea is a thin layer of gray tissue extending from
the corpus callosum to the optic commissure. The fissure of Sylvius,
between the frontal and middle lobes, lodges the middle cerebral artery,
38 THE REGION OF THE HEAD.

and the fissure begins in the vallecula, which is also known as the anterior
perforated space, because it is perforated by the vessels which supply the
corpus striatum. This anterior perforated space is the apparent origin of
the three roots of the first cranial nerves (or olfactory bulbs) (Plate 6, Fig.
2), on each side. Each olfactory bulb is received into a straight furrow
on the orbital surface of the frontal lobe and lies on the cribriform plate
of the ethmoid bone (Plate 3, Fig. 1, No. 1). The outer white root of
the olfactory bulb originates in a nucleus of gray matter in the anterior
part of the middle lobe of the hemisphere, and from the fissure of Sylvius
passes along the outer side of the anterior perforated space. The middle
gray root takes origin from the anterior perforated space and the furrow
in which it rests on the frontal lobe. The inner white root arises from
the gyrus fornicatus on the median surface of the hemisphere. The olfac-
tory bulbs are in reality the prolongations of the frontal portions of the
cerebral substance. On their under surface, as they rest on, the cribri-
form plate of the ethmoid bone, they give off about twenty nerves, which
are distributed to the nasal mucous membrane (page 116). Behind the
lamina cinerea is the optic commissure, formed by the union of the optic
tracts, which arise from the anterior lobes (nates) of the corpora quadri-
gemina, the corpora geniculata, and the posterior portions of the optic
thalami, winding round the crura cerebri.

In the skull the optic commissure rests upon the olivary process
of the sphenoid bone, and from it the second cranial nerves (or optic),
surrounded by prolongations of the dura mater, pass into the orbits
through the optic foramina and enter the back of the eyeballs (Plate
5, Fig. 2, Nos. 8 and 21), eventually expanding into the retine. The
ophthalmic arteries accompany the optic nerves through the optic foramina.
The commissure consists of lateral fibres which pass from one optic tract
to the optic nerve of the same side, anterior fibres which pass from one
optic nerve to the other optic nerve, posterior fibres which pass from one
optic tract to the other optic tract, and middle decussating fibres which
cross from the optic nerve of one side to the optic tract of the other side.

The tuber cinereum is the gray prominence behind the optic commis-
sure. This prominence is the floor of the third ventricle of the brain,
THE REGION OF THE HEAD. 39

and from it is projected a red-colored conical tube, the infundibulum, to
which is attached the pituitary body (Plate 5, Fig. 3, No. 20). The
pituitary body is lodged in the sella turcica of the sphenoid bone (Plate
12, No. 27), and is difficult to retain in removing the brain from the
skull. It consists of two lobes, the posterior one being originally a pro-
longation downward of the cavity of the third ventricle through the
infundibulum. Usually in later life the cavity in the posterior lobe of
the pituitary body is obliterated. Behind the tuber cinereum are the
corpora albicantia (Plate 6, Fig. 2, No. 34), which are formed by the
bulbs of the fornix, the fibres of which pass downward, and then, after
twisting in a figure-of-eight manner, pass upward to end in the optic
thalami (Plate 8, Fig. 2, No. 11). Posterior to the corpora albicantia is
a gray depression perforated by vessels which supply the optic thalami:
it is called the posterior perforated space. It is placed between the
diverging crura cerebri and in front of the pons Varolii. The crura
cerebri consist of longitudinal fibres from the pons Varolii and upper part
of the medulla oblongata, which pass forward and outward to the middle
lobes of the hemispheres (Plate 6, Fig. 2). Division of one of the crura
will exhibit in its middle some dark-colored tissue, called the locus niger,
which separates the crus into two layers of fibres. The lower layer (the
crusta) consists of coarse fibres arising from the anterior portion of the
medulla and the pons. The upper layer (the teymentum) is composed of
fine fibres from the lateral portions of the medulla oblongata and also
from the corresponding crus of the cerebellum. The lower fibres of each
crus cerebri pass chiefly through the corpora striata, and the upper fibres
through the optic thalami. In their passage through the ganglionic
masses the fibres are greatly augmented, and, branching out, are dis-
tributed to the cortical substance on the surface of the hemispheres.
The third cranial nerves (or oculo-motor) appear just in front of the
pons Varolii, issuing from among the fibres on the inner sides of the
crura cerebri (Plate 6, Fig. 2, No. 11). These nerves originate from
yellow nuclei beneath the passage-way between the third and fourth ven-
tricles (aqueduct of Sylvius) (Plate 8, Fig. 1, No. 9), whence they pass
forward through the locus niger and tegmentum in each of the crura, and,
40 THE REGION OF THE HEAD.

after passing through the plexus of veins called the cavernous sinus, in
close relation to the internal carotid arteries, enter the orbits by means
of the sphenoidal fissures, to be distributed to the muscles of the eye-
balls, with the exception of the external recti and the superior oblique.

The fourth cranial nerves (or trochlear) (Plate 6, Fig. 2, No. 13) wind
round the outer sides of the crura cerebri, having each originated from
a gray nucleus in the floor of the aqueduct of Sylvius, very near the yellow
nuclei of the third nerves. Their fibres decussate in the roof of the aque-
duct, called the valve of Vieussens, about the middle line. They enter
the orbit by the sphenoidal fissure and supply the superior oblique
muscles (Plate 5, Fig. 2, No. 11).

The fifth cranial nerves (or trifacial) appear at the base of the brain,
each issuing in two separate bundles of fibres from the sides of the pons
Varolii near its anterior border (Plate 8, Fig. 2, Nos. 15 and 16). These
nerves are the largest of the cranial nerves, and, owing to their complex
character and important associations, are of the greatest interest. Each
nerve has two distinct roots, and therefore resembles a spinal nerve; the
anterior root is the smaller, consisting of three or four bundles of
fibres, and having motor function, and the posterior the larger, com-
posed of from seventy to one hundred bundles of fibres, and possessed of
sensory function. The motor influences are chiefly confined to the muscles
of mastication, while the sensory branches are distributed throughout the
head and face (Plate 53, Fig. 1, No. 19). The two roots of this nerve
commence in the upper portion of the medulla oblongata, the sensory
root originating in the gray tubercle of Rolando, and the motor root from
a nucleus of large cells closely connected with the posterior cornu of the
medulla wherein the tubercle is situated. On its way forward the motor
root receives some fibres from the floor of the fourth ventricle and also
from the sides of the aqueduct of Sylvius. |

As the two roots issue from the pons Varolii they are separated from
each other by a few of the transverse fibres of this body. They proceed
forward on the apex of the petrous portion of the temporal bone, where
there is a depression (Plate 3, Fig. 5, No. 3) for a semilunar ganglionic
enlargement which occurs here upon the sensory root. This is the Gas-
THE REGION OF THE HEAD. 41

sertan ganglion (Plate 5, Fig. 2, No. 25), and it furnishes additional resem-
blance to a spinal nerve, being somewhat similar to the ganglia on their
posterior roots (Plate 4, Fig. 2). The motor root passes beneath the
ganglion, and has no connection with it,—proceeding independently with
the inferior maxillary branch of the sensory root through the foramen
ovale, and after its exit at this foramen blending its fibres with those of
that nerve. From the anterior border of the Gasserian ganglion three
great nerve-trunks are given off,—viz., the ophthalmic nerve, which passes
through the sphenoidal fissure with the third, fourth, and sixth nerves
and the ophthalmic vein, the superior mazillary nerve, which passes
through the foramen rotundum, and the inferior maxillary nerve, which
passes through the foramen ovale, by which the lesser meningeal artery
(Plate 3, Fig. 2) also enters the skull.

The sixth cranial nerves (or abducent) emerge between the pons and
the anterior pyramids of the medulla oblongata (Plate 6, Fig. 2, No. 17),
being connected with both of them. Their deep origins are in the fasciculi
teretes in the floor of the fourth ventricle. They leave the skull by the
sphenoidal fissures, passing between and supplying the two portions of the
external recti muscles of the eyeballs (Plate 5, Fig. 2, No. 13).

The seventh cranial nerves (or facial) have their deep origins in the
floor of the fourth ventricle, whence they pass more superficially than the
sixth nerves, and, bending abruptly upon themselves, emerge between the
pons and the restiform tract of the medulla oblongata. They enter the
internal auditory openings in the temporal bones, and, after passing through
the aqueduct of Fallopius (Plate 3, Fig. 5, No. 9) and giving off petrosal
branches in their course, pass out by the stylo-mastoid foramina, to be
distributed to the facial muscles.

The eighth cranial nerves (or auditory) also arise from the floor of the
fourth ventricle, and are in close relation with the seventh nerves, a con-
necting link of nerve-tissue (the pars intermedia of Wrisberg) being
interposed between both of them on each side. On account of this
intimate relation, the facial and auditory nerves were formerly classified
as two separate portions of the seventh cranial nerve, and because of

their difference in character the former was called the portio dura and
6
0: ETS AER Ry OO BOF Fos

Hee
RoOWRowo

SLEwrannwone

PLATE 6.

Figure 1.

The upper surface of the brain of a white man about forty-five years of age, in sound condition and normal in
general conformation, size, and weight. The right hemisphere is larger than the left, the longitudinal fissure not being
in the middle of the cerebral mass. The pia mater has been removed to demonstrate the surface markings.

. The longitudinal fissure. 11
. The left frontal lobe. 12
. The left fissure of Rolando. 18.
. The left parietal lobe. 14
. The left calloso-marginal fissure. 15

The left supra-marginal convolution.

The left angular convolution (gyrus). 16.

The left occipital lobe. 17.
. The right superior frontal convolution. 18.
. The right middle frontal convolution. 19.

Figure

. The right inferior frontal convolution.

. The right ascending frontal convolution,

. The right fissure of Rolando.

. The right ascending parietal convolution.

. The end of the horizontal branch of the right fissure

of Sylvius.
The right parieto-occipital fissure.
The right inferior occipital convolution.
The right middle occipital convolution.
The right superior occipital convolution.

2s

The under surface of the same brain as in Figure 1, showing the superficial origins of the cranial nerves, The pia
mater is removed from the cerebrum, although retained over the cerebellum.

The longitudinal fissure.

The right olfactory convolution.

The right orbital convolution.

The right frontal lobe.

The right olfactory bulb (or first cranial nerve).
The right fissure of Sylvius.

The lamina cinerea.

The right optic nerve (or second cranial nerve).
The right temporo-sphenoidal lobe.

The right middle temporo-sphenoidal convolution.

. The right oculo-motor nerve (or third cranial nerve).
2. The right inferior temporo-sphenoidal convolution.

. The right trochlear nerve (or fourth cranial nerve).

. The lobulus fusiformis.

15,

The motor root of the right trifacial nerve (or fifth
cranial nerve).

. The sensory root of the trifacial nerve.

. The right abducent nerve (or sixth cranial nerve).

. The right facial nerve (or seventh cranial nerve).

. The right auditory nerve (or eighth cranial nerve).

. The right glosso-pharyngeal nerve (or ninth cranial

nerve).

. The right pneumogastric nerve (or tenth cranial nerve.)
. The right hypoglossal nerve (or twelfth cranial nerve).
. The right spinal accessory nerve (or eleventh cranial

nerve).

. The gray substance of the medulla oblongata.

 

25.
26.
27.

The right lobe of the cerebellum.

The left first frontal convolution (gyrus rectus).
The left middle frontal convolution.

The left third frontal convolution.

. The left olfactory bulb (or first cranial nerve).

. The left fissure of Sylvius.

. The anterior perforated space.

. The optic commissure.

. The pituitary body.

. The corpora albicantia.

35. The left oculo-motor nerve (or third cranial nerve),
. The posterior perforated space.

. The left trochlear nerve (or fourth cranial nerve).

. The left trifacial nerve (or fifth cranial nerve).

. The pons Varolii.

. The left abducent nerve (or sixth cranial nerve).

. The left facial nerve (or seventh cranial nerve).

. The left auditory nerve (or eighth cranial nerve).

. The left glosso-pharyngeal nerve (or ninth cranial

nerve).

. The left pneumogastric nerve (or tenth cranial nerve).
. The left olivary body.

. The left hypoglossal nerve (or twelfth cranial nerve).

. The left spinal accessory nerve (or eleventh cranial

nerve). :

. The left occipital lobe of the cerebrum.
. The left lobe of the cerebellum.
Plate 6 ie

pales

iy
oe

(Ww)!

IO

7
|

aS

» BESWU
Y=0.00

 

2 ee 7
Lissacted, Photographed and Colored rrom Nature by Georce Mc. Crec.an, M D, Copyright /89/ by CeoreeMe Creti an MD. a eae
THE REGION OF THE HEAD. 43

the latter the portio mollis. The auditory nerves commence by fibres
which originate in the outer and inner auditory nuclei beneath the
acoustic tubercles on each side of the floor of the fourth ventricle, and,
after receiving some fibres from the transverse strie in this situation,
unite into individual trunks which enter the internal auditory openings
of the temporal bones in company with the facial nerves. Within the
auditory openings these nerves subdivide into cochlear and vestibular
branches, which are distributed to the internal ears (page 78).

The ninth cranial nerves (or glosso-pharyngeal) appear on the surface
of the restiform bodies, below the auditory nerves (Plate 6, Fig. 2, No. 20).
The deep origins of these nerves are very close to those of the auditory
nerves in the floor of the fourth ventricle. They make their exits from
the cranium by means of the middle compartments of the jugular foramina,
and are distributed to the mucous membrane of the pharynx and back of
the tongue (Plate 13, Fig. 2, No. 16).

The tenth cranial nerves (or pneumogastric) also appear on the restiform
bodies, in close proximity to the preceding nerves (Plate 6, Fig. 2, No. 21).
Their fibres of origin arise from special nuclei in the inferior part of the
fourth ventricle, and soon blend together, forming single nerve-trunks
which’ pass through the jugular foramina and are distributed to the
pharynx, larynx, heart, lungs, cesophagus, and stomach (Plate 36, No. 61,
and Plate 37, No. 32). The pneumogastric nerve is of extreme interest
and importance, and is often called the vagus nerve, from its wandering
course.

The eleventh cranial nerves (or spinal accessory) are each composed
of two separate parts, an upper or accessory part, which arises from
the medulla below the pneumogastric, and a lower part, which arises
from the spinal cord (Plate 6, Fig. 2, No. 23). The deep origin of the
upper part commences in a special nucleus about the calamus scriptorius
in the fourth ventricle. The spinal part of this nerve is composed of
fibres which originate as low down on the cord as the fifth cervical
vertebra, and it enters the skull at the foramen magnum to join the
accessory part. The combined nerve then passes out of the jugular
foramen with the pneumogastric and glosso-pharyngeal nerves, the acces-
44 THE REGION OF THE HEAD.

sory portion blending with the pneumogastric, while the spinal portion
(Plate 18, Fig. 1, No. 8, and Plate 21, No. 18) supplies the sterno-
mastoid and trapezius muscles.

The twelfth cranial nerves (or hypoglossal) appear on the surface of the
medulla oblongata, in the grooves between the olivary bodies and the
anterior pyramids (Plate 6, Fig. 2, No. 46). The special nuclei from
which the fibres of these nerves originate are to be found on the floor
of the fourth ventricle in front of and nearer the middle line than the
nuclei for the pneumogastric nerves. The fibres are formed into two
bundles which pierce the dura mater through separate openings and
afterward combine within the anterior condyloid foramina, their final
distribution being to the muscles of the tongue (Plate 13, Fig. 2, No.
19) and the depressor muscles of the hyoid bone and larynx.

It will be noticed that most of the cranial nerves originate in the
neighborhood of the fourth ventricle (or ventricle of the cerebellum) and
the top of the medulla oblongata. These portions of the brain are there-
fore of the greatest importance. The pons Varolii and the medulla oblon-
gata, which rest upon the basilar portions of the occipital and sphenoid
bones, have in the natural state interposed between them and the bone,
as well as between them and the superposed cerebrum and cerebellum, a
quantity of cerebro-spinal fluid which collects in the anterior and posterior
sub-arachnoidean spaces. 'This fluid serves to equalize pressure and affords
resistance to shock, especially from the effects of injury by conére-coup.
The sub-arachnoid space communicates with the ventricular cavities of the
brain by the foramen of Magendie, which is an aperture in the pia mater
closing in the fourth ventricle. The aqueduct of Sylvius connects the
fourth ventricle with the third ventricle at the base of the brain, and
the latter is connected in front with the lateral ventricles by the foramen
of Monro.

The medulla oblongata (Plate 6, Fig. 9, No. 24) is the upper expanded
extremity of the spinal cord on a level with the lower border of the
foramen magnum. It is a white, pyramidal body, two and one-half
centimetres, or about an inch, in length, and is partially divided anteri-
orly and posteriorly by median fissures. The anterior median fissure ends
THE REGION OF THE HEAD. 45

in the foramen cecum just below the pons Varolii. The posterior median
jissure expands into the floor of the fourth ventricle. Each half of the
medulla oblongata consists of four longitudinal masses,—viz., the anterior
pyramids, the lateral tracts and olivary bodies, the restiform bodies, and
the posterior pyramids. The anterior pyramids increase in breadth as
they approach the pons Varolii, through which their fibres pass to reach
the crura cerebri. They are continuous with the anterior columns of the
spinal cord, and consist of motor fibres. When the anterior pyramids are
separated at their commencement, their inner nerve-fibres, below the
surface, are readily seen decussating at the bottom of the anterior fissure.
The outer fibres do not decussate, and ascend directly upward. An injury
received upon one side of the brain is followed by loss of motion on the
opposite side of the body (cross-paralysis), which effect is explained by
the decussation of the inner fibres of the medulla which are continuous
with the fibres of the lateral tracts of the opposite sides.

The Jateral tracts are situated on the outer side of the anterior pyra-
mids. The olwary bodies project from the upper part of the lateral tracts,
being separated by a depression from the pons. They are embraced by
the ascending fibres of the lateral tracts as they diverge on their way to
the pons and restiform bodies. These ascending fibres from the lateral
tracts are more or less obscured by the arciform fibres, which loop across
the surface and connect the anterior pyramids with the restiform bodies.
The roots of the hypoglossal, glosso-pharyngeal, pneumogastric, and spinal
accessory nerves emerge from the medulla in the immediate vicinity of the
olivary bodies. The olivary nucleus is a layer of gray tissue within the
olivary body upon each side, which presents on section a jagged toothed
appearance, in consequence of which it is also called the corpus dentatum.
The restiform bodies are the continuation upward of the posterior columns
of the spinal cord. They diverge toward the cerebellum, constituting
its inferior peduncles, and with the posterior pyramids assist in forming
the lateral boundaries of the fourth ventricle. Gray matter is found in
the interior of the restiform bodies.

The posterior pyramids (funiculi graciles) are the two slender bundles
on each side of the posterior median fissure, which diverge at the apex
46 THE REGION OF THE HEAD.

of the fourth ventricle. The enlargement upon each of the posterior
pyramids at this locality is called the clava, and it contains within it
some gray matter, the nucleus gracilis. From the clava the posterior
pyramid on each side gradually dwindles, its fibres passing to the cere-
brum along the floor of the fourth ventricle and constituting with the
fibres from the adjacent restiform body, which take the same course, the
fasciculi teretes. The transverse striw on the floor of the fourth ventricle, —
which form the roots of the auditory nerves, are derived from the arci-
form fibres above described. They are chiefly composed of the fibres
which do not enter the olivary body, but wind round beneath it and over
the restiform body. The decussation of the fibres of the lateral tracts
and the divergence of the restiform bodies and posterior pyramids cause
a change in the arrangement of the gray matter in the upper part of ©
the medulla oblongata, from the characteristic disposition of the gray
matter in the spinal cord. The anterior cornua of the cord become
separated from the mass of gray matter, owing to the decussation of the
fibres from the lateral tracts, and behind the olivary bodies form the
lateral nuclei. The rest of the gray matter of the anterior cornua in
this locality is. broken up into an interlacement of fibres, the formatio
reticularis, by the longitudinal fibres from the lateral tracts being inter-
sected by the deeper set of arciform fibres.

The pons Varolii (Plate 6, Fig. 2, No. 39) is situated just above the
medulla oblongata, and in the skull rests upon the body of the sphenoid
bone. It serves to connect the fibres of the medulla below with the
cerebellum behind it by means of the crura cerebelli, as well as with
the cerebrum above by means of the crura cerebri. The pons is defined
above and below by very prominent margins, the upper margin arching
over the crura cerebri, and the lower one, much less curved, distin-
guishing it from the medulla. A shallow groove in the middle of its
anterior surface accommodates the basilar artery (Plate 11, Fig. 1, No.
15). A section of the pons will show that the anterior portion is mainly
composed of white transverse fibres crossed by white longitudinal fibres.
The longitudinal fibres ascend from the medulla to pass to the cerebrum,
and occasion the prominences on each side of the anterior surface of the
THE REGION OF THE HEAD. 47

pons. The transverse fibres connect the hemispheres of the cerebellum.
These fibres are arranged in layers having gray matter variously disposed
among them, especially in the locality of the fourth ventricle, where
most of the cranial nerves have their origin.

The cerebellum in the skull (Plate 5, Fig. 2, Nos. 14 and 27)
occupies the inferior occipital fosse, being protected by the tentorium of
the dura mater from the weight of the overlying posterior lobes of the
cerebrum. It consists of two lateral lobes or hemispheres separated pos-
teriorly by the falx cerebelli of the dura mater and joined anteriorly by
the vermiform process, or central lobe.

The cortical surface, which is darker than that of the cerebrum, is
arranged in parallel curved folds, with intervening fissures which vary
in depth from the centre and subdivide the surface into lobules. There
are four lobules on each hemisphere, the marginal lobule, the lobulus
gracilis, the cuneiform or digastric lobule, and the amygdala or tonsil
lobule. The horizontal fissure separates the upper and lower surfaces
of each hemisphere of the cerebellum. The space between the two
hemispheres below is called the valley. The upper surface consists of
the expanded middle lobe, which is here designated the superior vermis.
In front there is a notch into which the optic lobes are received, the surface
overlapping the superior peduncles of the cerebellum and the valve of
Vieussens. Behind them is another notch, into which the internal occipital
protuberance projects. The superior vermis is subdivided into four parts.
The central lobule stands out prominently in front; beneath this and over
the valve of Vieussens is the lingula, a flattened transverse lamella, with
small ridges extending into it from the crura cerebelli, the /renula.
Behind the central lobule is the monticulus cerebell, and posteriorly is
the smaller portion called the commissura simplex.

The lamelle constituting the monticulus continue into the quadrilateral
lobules on each side, and those which form the commissura pass to the
posterior or crescentic lobules. The inferior vermis can best be seen after
removing the amygdale. It consists of three portions,—the pyramid, the
uvula, and the nodulus. At the anterior part of the under surface is the
sub-peduncular lobule, or flocculus. Passing from the nodulus to the floc-
Bee
Her oo MONA ATL WH eS

e
2

PLATE 7.

Figure

1.

The convolutions and fissures on the external surface of the right hemisphere. (Of same brain as in Plate 6.)

. The fissure of Rolando.

. The ascending parietal convolution,
. The superior parietal convolution.
. The calloso-marginal fissure.

. The inter-parietal fissure.

. The inferior parietal convolution,

. The angular convolution.

. The occipito-parietal fissure.

. The superior occipital convolution.
. The middle occipital convolution.

. The inferior occipital convolution.
. The transverse fissure (of Bichat).
. The right lobe of the cerebellum.

. The ascending frontal convolution.

. The superior frontal convolution,

. The posterior frontal fissure. :

. The middle frontal convolution.

. The horizontal branch of the fissure of Sylvius.
. The inferior frontal convolution.

. The ascending branch of the fissure of Sylvius.
. The superior temporal convolution.

. The fissure of Sylvius.

. The middle temporal convolution.

. The inferior temporal convolution.

. The pons Varolii.

. The medulla oblongata.

Figure 2. :

The convolutions and fissures on the external surface of the left hemisphere. (Of same brain as in Plate 6.)

. The fissure of Rolando.
. The ascending frontal convolution.

The superior frontal convolution.
The posterior frontal fissure.

. The middle frontal convolution.

The horizontal branch of the fissure of Sylvius.

. The central lobe, seen on this side externally, in the

fork of the fissure of Sylvius.

. The ascending branch of the fissure of Sylvius.
. The inferior frontal convolution.

. The superior temporal convolution,

. The middie temporal convolution.

. The fissure of Sylvius,

. The optic nerve.

14.
15.
16,
17,
18,
19.
20.
21,
22.
23.
24,
25.
26.
27.

The inferior temporal convolution.
The pons Varolii.

The medulla oblongata.

The calloso-marginal fissure.

The ascending parietal convolution.
Annectant convolutions.

The inter-parietal fissure.

The occipito-parietal fissure.

The angular convolution.

The superior occipital convolution.
The middle occipital convolution.
The inferior occipital convolution.
The transverse fissure.

The left lobe of the cerebellum.
Plate 7
Wen!

 

Copyright/89/.by GeorseMc Cte. an/.D.

Dissected, Photographed and Colored from Nature by Georce Mc. Crectan, MD.

 
THE REGION OF THE HEAD. 49

culus is a thin valve-like fold of white matter, which is called the posterior
medullary velum. This velum as it passes from the cerebellum becomes a
very delicate layer of tissue covered with pia mater, and closes in the fourth
ventricle. A longitudinal section of one of the hemispheres (Plate 11,
Fig. 8, and Plate 12) will disclose a mass of white substance with radiating
branches upon which the gray cortical substance is infolded. This is the
arbor vite of the cerebellum (Plate 8, Fig. 1, No. 12). The white sub-
stance of each hemisphere contains in its centre a nucleus of gray matter,
the corpus dentatum.

The function of the cerebellum has been concluded from physiological
observations to be the co-ordination of muscular movements. As above
described, the cerebellum is connected with the medulla oblongata by the
fibres which ascend from the restiform tracts and constitute the inferior
peduncles, or inferior crura. The lateral parts of the pons Varolii are
the middle peduncles, or middle crura, of the cerebellum; and its superior
peduncles, or superior crura, are the fibres which connect it with the cere-
brum. The innermost fibres of the superior peduncles decussate beneath
the corpora quadrigemina, so that some fibres from one half of the cerebrum
are continued into the opposite half of the cerebellum. Many of these
fibres have been traced into the corpora dentata. Each of the superior
peduncles (processus e cerebello ad testes) forms the upper part of the
lateral boundary of the fourth ventricle, and is connected with its opposite
fellow by means of the valve of Vieussens, or superior medullary velum.
The valve is a thin layer of gray matter which forms the upper wall or
roof of the important fourth ventricle (Plate 8, Fig. 2, No. 26).

The fourth ventricle is the space between the cerebellum and the
posterior surfaces of the medulla oblongata and the pons Varolii. Upon
vertical section (Plate 8, Fig. 1, No. 10) it appears triangular in shape.
This subdivision of the general ventricular cavity is the first part of the
primordial central canal formed in the foetus. As just stated, the fourth
ventricle is roofed over by the valve of Vieussens, bounded on each side
by the superior peduncles of the cerebellum, and behind by the diverging
posterior pyramids and restiform bodies.

Inferiorly the arachnoid membrane is continued on to the posterior
7
50 THE REGION OF THE HEAD.

surface of the spinal cord; an aperture usually existing here, called the
foramen of Magendie, by which the ventricle communicates with the sub-
arachnoidean space. A median furrow exists in the floor of this ventricle,
which begins below in a pit (the ventricle of Arantius) and ends in the
aqueduct of Sylvius. The divergence of the inferior cerebellar peduncles
from this median furrow constitutes a resemblance to the point of a quill
pen, and forms the calamus seriptorius of the old anatomists. The odex is
an arching fold of. tissue hanging over the apex of the calamus scriptorius.
On each side of the median furrow are longitudinal eminences, the fascicul
teretes, which are crossed by the transverse strie (or striw acoustice) toward
the posterior part of the ventricle. Externally to the fasciculus teres on
each side is a shallow groove which terminates below in a depression, the
fovea posterior, within which is the cinereous eminence. The fovea anterior
is another depression in this groove, opposite the widest part of the
ventricle. The auditory eminences are on each side between the fovee.
These are crossed by the above-mentioned striw acoustice. The locus
ceruleus is the name given to a variable bluish-gray nucleus in the upper
angle of the ventricle. Besides these objects on the floor of the fourth
ventricle there are the nuclei of the cranial nerves which originate here.
The pia mater (velum interpositum), lining the fourth ventricle, is con-
tinued into the third ventricle by the aqueduct of Sylvius (or iter a
tertio ad quartum ventriculum). The aqueduct is about half an inch
long, and contains in its walls a large amount of gray matter, in which
are the nuclei for the third, fourth, and upper part of the fifth cranial
nerves. In front of and above the aqueduct of Sylvius are two pairs
of bodies,—the corpora quadrigemina (Plate 8, Fig. 2, No. 24), or
more properly the optic lobes, as they give origin to the optic nerves.
They are relatively smaller in man, although their size in most animals
bears relation to the power of sight. In birds there is only one pair of
optic lobes; in the early stage of the human embryo there is only
one pair also, but about the seventh month of foetal life this pair is sub-
divided into two by a ‘transverse groove. The posterior pair are the
smallest, and are called the testes; the anterior. pair, the nates, are
larger and of a darker color. Immediately in front of the nates is situ-
THE REGION OF THE HEAD. dl

ated a very vascular cone-shaped body,—the conariwm, or pineal gland.
It is about the size of a cherry-stone, and consists of many small follicles
containing cells. These cells have a gritty substance within them (acervu-
lus cerebri) consisting of carbonate of calcium and phosphate of calcium
and of magnesium. This curious little body is larger in the child and in
the adult female than in the adult male. Its function is unknown, but
in birds is supposed to be associated with their homing instinct. The
pineal gland is connected with the cerebrum by two white bands or crura
(the peduncles of the pineal gland) which extend forward upon the inner
sides of the optic thalami in the lateral walls of the third ventricle.

The third ventricle is the narrow oblong fissure into which the-aque-
duct of Sylvius, which passes beneath the corpora quadrigemina, opens
anteriorly. Its floor is formed by the parts within the inter-peduncular
space at the base of the brain,—viz., the posterior perforated space, the
corpora albicantia, the tuber cinereum, the infundibulum, and the lamina
cinerea (Plates 6 and 8). The velum interpositum is stretched across
above, and with the fornia, the arching layer of white matter beneath the
corpus callosum, forms the roof of the third ventricle.

The cavity of this ventricle is crossed by three commissural bands.
The posterior commissure is just in front of the pineal gland, and is com-
posed of white fibres which serve to connect the optic thalami. The
middle or soft commissure is about half an inch broad, composed of gray
matter, and also serves to connect the optic thalami. It is not always
found even upon careful examination. The anterior commissure is a round
white cord in the fore part of the cavity of the ventricte, the fibres of which
pass through the adjacent corpora striata and extend into the temporo-
sphenoidal lobes of the cerebrum. Just behind the anterior commissure
is the foramen of Monro, an aperture leading into a short passage which
soon branches after the manner of the letter Y, thus affording a com-
munication between the third ventricle and the two lateral ventricles, by
which the choroid plexuses of opposite sides are joined. The velum in-
terpositum is a duplicature of the pia mater which is projected into the
ventricular cavity of the cerebrum through the breach between its posterior
lobes and the cerebellum (the transverse fissure of Bichat, Plate 8, Fig.
52 THE REGION OF THE HEAD.

2, No. 22). Its shape corresponds to that of the fornix, its projecting
borders being the convoluted fringes called the choroid plexuses (Plate
11, Fig. 2, Nos. 8 and 19). These plexuses consist of minute arteries
and veins in connective tissue. In the centre of the velum are two
large veins (the vene Galeni) which convey the blood from the great
cerebral ganglia into the straight sinus (Plate 4, Fig. 1, No. 9).

The ganglionic masses at the base of the brain consist of two pairs.
The anterior are called, from their internal arrangement of alternate white
and gray layers, the corpora striata. The posterior are the optic thalami,
which are oval, elevated masses placed on each side of the third ventricle,
and, embracing the crura cerebri, project portions of their upper surfaces
in the floors of the lateral ventricles. They are exposed by removing the
choroid plexuses. They are composed of gray substance covered with a
superficial thin layer of white tissue. The upper surface of each thalamus
is subdivided by an oblique groove into an anterior tubercle and a posterior
tubercle, or pulvinar. Beneath and behind the optic thalami on each side
are two small gray eminences, known as the corpora geniculata, internum
and eaternum according to their position. They are in relation to the
roots of the optic tract (the drachia), and are connected posteriorly by
white bands with the corresponding corpora quadrigemina.

The inner margins of the optic thalami are covered by the choroid ©
plexuses, which separate them from the fornix, which is the layer of white
matter arching over the inter-thalamic region and enclosing the third
ventricle.

The fornix consists of a triangular central portion, the body, the
broadest part of which is posterior to and closely connected with the
corpus callosum, and anterior and posterior prolongations, known as the
pillars or crura of the fornia. The posterior pillars descend from the
outer angles of the body into the middle cornua of the lateral ventricles,
constituting the hippocampi majores and terminating in the pes hippocampi.
In their course they are in contact with the pulvinar of the optic thalamus
on each side. The anterior pillars curve downward from the front of
the body of the fornix, leaving the corpus callosum about the position of
the foramen of Monro in the floor of the third ventricle, and, receiving
THE REGION OF THE HEAD. 53

the peduncles of the pineal gland and fibres from the tenia and septum
lucidum, pass to the base of the brain, their component fibres twisting in a
figure-of-eight manner and returning upward and backward into the fore
portions of the optic thalami. The curve which the fibres of each anterior
pillar take at the base of the brain forms the corpus albicans of that side,
as has been previously stated in the view of that region.

On the portion of the under surface of the fornix which rests on the
velum interpositum there are some transverse fibres which pass from
the corpus callosum and form the lyra.

The septum lucidum (Plate 8, Fig. 2, No. 6) is a delicate, almost trans-
lucent, vertical partition extending from the front of the fornix, where it
bends downward, and attached above and below to the under surface of the
corpus callosum. It consists of two layers, gray on the inside and white
without, and the space between them is called the fifth ventricle. This
septum serves to divide the upper ventricular space within the hemi-
spheres of the cerebrum into the right and left lateral ventricles. In
cases of serous effusion within the general ventricular cavity of the brain
the septum is often ruptured and free communication exists from side
to side.

The lateral ventricles (Plate 11) are semilunar in shape, and consist of
a central part, or body, and anterior, middle, and posterior cornua, which
extend respectively into the frontal, temporo-sphenoidal, and occipital lobes.
The floor of the central portion of either of the lateral ventricles presents
many objects of interest, which have the following relative positions.
Posteriorly the margin of the posterior pillar of the fornix (the corpus
jimbriatum) appears as a white cord accompanying the hippocampus major
and sometimes called on this account the tenia hippocampr. In front of
this is the choroid plexus, which usually extends so far forward into the
cavity that very little of the subjacent optic thalamus is seen unless it is
purposely uncovered. Beyond the thalamus, and separating it from the
caudate portion of the corpus striatum, or anterior ganglionic mass, is the
white band called from its course the tenia semicircularis. The teenia
descends anteriorly in connection with the anterior pillar of the fornix,
and blends with the fibres composing the corpus albicans, as previously
54 THE REGION OF THE HEAD.

described. Posteriorly it passes into the middle cornu of the lateral
ventricle, apparently losing itself in the white substance in that cavity,
but eventually terminating in the gray mass, the nucleus amygdala.
Owing to the upper surface of the tenia being somewhat harder than
its deeper part, it was called by Tarinus the horny band.

In the fore part of the centre of the lateral ventricle is seen the intra-
ventricular portion of the corpus striatum (Plate 11, Fig. 2, No. 15). This
ganglionic centre is best understood by making a horizontal section through
it from the tenia semicircularis outward, where it appears to consist of. five
parts. The intra-ventricular portion, or the caudate nucleus, of the corpus
striatum, above mentioned, is a gray, pear-shaped mass, the broad part of
which is directed forward into the lateral ventricle, and its narrow end,
the tail or surcingle, is continued into the middle cornu as far as the
nucleus amygdale. The surface of the caudate nucleus in the recent state
is covered with a plexus of veins which empty into the vene Galeni. The:
extra-ventricular portion or lenticular nucleus (Plate 11, Fig. 1, No. 6) of.
the corpus striatum is the largest, and is lodged within the white substance
of the hemisphere, being separated from the caudate nucleus by a layer
of white matter, the internal capsule (Plate 11, Fig. 1, No. 12).

On the external surface of the lenticular nucleus is another layer of
white tissue, the external capsule (Plate 11, Fig. 1, No. 30), which again
separates this portion from a thin layer of gray matter, the claustrum.
External to the latter is the white matter which is subjacent to the central
lobe, or island of Reil, the claustrum being formed by a portion of the
under surface of the convolutions of the latter turned inward.

A vertical transverse section of the lenticular, nucleus demonstrates
that it is composed of three smaller nuclei, the inner one gray, the
middle dark yellow, and the outer of a reddish color. These parts are
separated by layers of fibres which originate in the convolutions of the
operculum. The nucleus amygdale underlies the corpus striatum, and is
in relation with the tail of the caudate nucleus, being continuous with
the deep-seated cortex of the temporal lobe. The caudate and lenticular
nuclei are united by many gray striz, which cross the internal capsule
and give to the mass the peculiar striation to which it owes its name.
THE REGION OF THE HEAD. 50

The internal capsule consists of white fibres passing between the caudate
nucleus and the thalamus opticus and the lenticular nucleus. Its anterior
portion, or caudo-lenticular limb, is composed of fibres from the frontal
lobe, and its posterior portion, or thalamo-lenticular limb, consists of
motor fibres from the operculum on their way through the crusta of the
crus cerebri to the anterior pyramid of the medulla oblongata. Fibres
from the temporal and occipital lobes also compose the extreme end of
the thalamo-lenticular limb, passing through the crus cerebri and pons
to the cerebellum. There are also fibres passing from the cortex to the
thalamus and to the gray matter in the pons. These fibres diverge above
the caudate nucleus and intermingle with the fibres of the corpus callosum.
The external capsule is thinner than the internal, with which it is con-
tinuous behind. It consists of white fibres in connection with the claus-
trum derived from the crus cerebri and the anterior commissure of the
third ventricle.

The posterior cornua (or digital cavities) of the lateral ventricles
are not always equally developed in both hemispheres, and they are
sometimes absent. They usually curve backward into the substance of
the occipital lobes. In the floor of each posterior cornu is a claw-shaped
eminence, the hippocampus minor, which is also known as the calcar,
because it is produced by the infolding of the contiguous convolutions of
the calcarine fissure. Between the posterior and middle cornua there is
a smooth mass of variable size, the eminentia collaterals (or the pes acces-
sorius), formed by the inward protrusion of the collateral fissure. The
middle or descending cornua are the largest of the prolongations of the
cavity of the lateral ventricles. They pass downward into the temporo-
sphenoidal lobes toward the base of the brain, making remarkable curves
backward, outward, and downward round the backs of the optic thalami,
and forward and inward round the crura cerebri, resembling somewhat
the horns of a ram, and hence are also known as the cornua Am-
monis. They terminate in close proximity to the fissures of Sylvius.
Continuous with the hippocampus minor, from the posterior cornu on
each side, is a long, white, rounded eminence which follows the curve

of the middle cornu and occupies the principal part of its cavity, the
SEIBS PEPE

Bee io
SaPas

Ne

SENSOR

Be
ro

12.
13.
14,
15,

i

PLATE 8.
Figure 1.

The convolutions and fissures of the inner surface of the left hemisphere of the cerebrum, and median section
through the base of the brain, cerebellum, pons Varolii, and medulla oblongata. (From same brain as in Plates 6 and 7.)

. The ascending frontal convolution.
. The fissure of Rolando.
. The ascending parietal convolution.

The precuneus, or quadrate lobe.
The parieto-occipital fissure.

The cuneus, or cuneate lobe.

The calcarine fissure.

The corpora quadrigemina,

. The aqueduct of Sylvius, leading from the third to the

fourth ventricle.

. The fourth ventricle.

. The transverse fissure.

. The arbor vite of the cerebellum.
. The left lobe of the cerebellum.

. The superior frontal convolution.

15. The calloso-marginal fissure.

16. The fornicate convolution.

17. The corpus callosum.

18. The anterior bend of the calloso-marginal fissure.
19. The septum lucidum.

20. The fornix.

21, The thalamus opticus.

22. The inferior frontal convolution.
23. The corpus albicans.

24. The optic nerve.

25. The fissure of Sylvius.

26. The motor oculi nerve.

27. The pons Varolii.

28, The temporo-sphenoidal lobe.
29. The medulla oblongata.

Figure 2.

The convolutions and fissures of the inner surface of the right hemisphere of the cerebrum, and median section
through the base of the brain, cerebellum, pons Varolii, and medulla oblongata. (From same brain as in Plates 6 and 7.3

The superior frontal convolution.
The calloso-marginal fissure.

The middle frontal convolution.
The fornicate convolution.

The corpus callosum.

The septum lucidum.

The fornix.

The anterior pillar of the fornix.
The optic thalamus.

. The inferior frontal convolution.
. The corpus albicans.

The optic nerve.

The motor oculi nerve.
The pons Varolii.

The medulla oblongata.

16. The fissure of Rolando.

17. The calloso-marginal fissure.

18. The quadrate lobe.

19, The corpus callosum.

20. The parieto-occipital fissure.

21. The cuneate lobe.

22. The velum interpositum.

23, The calcarine fissure.

24. The corpora quadrigemina.

25, The valve of Vieussens.

26. The great transverse fissure.

27. The fourth ventricle.

28, The arbor vite of the cerebellum.
29, The right lobe of the cerebellum.
PlateS Vouk

Fie | Bi res
rie b Flo 2

 

Dissected, Photographed and Colored from Wature by Georce Mc. CLettan, MD. Copynght/89/,by Georee Melee. an MD. ; Armstrong & Ca Lith Boston.

 
THE REGION OF THE HEAD. 57

hippocampus major. This body is formed by the reduplication of the
hippocampal convolution. Extending along its upper margin is the tenia
hippocampi, or white band continuous with the posterior pillar of the
fornix, as previously described. At the lower extremity of the hippo-
campus major there are four or five small elevations with intervening
depressions, producing a fancied likeness to the paw of an animal, and
hence called the pes hippocampr. Along the inner border of the hippo-
campus major about the hippocampal fissure (which is really the lateral
part of the transverse fissure) there is an edge composed of white fibres
from the fornix (corpus fimbriatum) passing to the uncinate gyrus. Here
there is a notched ridge of gray matter, the fascia dentata, which derives
its name from the arrangement of the choroid arteries as they pass
through the dentate fissure into the middle cornu. The anterior cornua
of the lateral ventricles curve outward from each other into the substance
of the frontal lobes round the caudate nucleus of the corpus striatum.
The general roof of the lateral ventricles is formed by the corpus
callosum, which, owing to its being formed of white transverse fibres
extending between the hemispheres, is called the great transverse commis-
sure of the cerebrum. The corpus callosum (Plate 8, Fig. 2, No. 5) is
thicker and broader at its back part, the spleniwm, which is in relation
with the transverse fissure where the pia mater enters the ventricles. It
arches forward over the ventricular cavity, ten centimetres, or about four
inches, in length, and anteriorly bends downward and backward, forming
the genu. The lowest part of the bend is called the rostrum (or beak),
and terminates in the two peduncles of the corpus callosum, they severally
disappearing in the fissures of Sylvius. Upon the upper.surface of the
corpus callosum there is a middle groove, or raphé, and, in the recent
state, on each side of this groove are readily distinguished two white
longitudinal strie, called the nerves of Lancisi. Parallel and external
to these are other fibres, the dateral striw. The anterior cerebral arteries
proceed from before backward on the upper surface, and are here called
the arteries of the corpus callosum (Plate 4, Fig. 1, No. 16). On its
external borders the corpus callosum is overlapped on each side by the
gyri fornicati (Plate 8). The borders themselves are known as the labia
58 THE REGION OF THE HEAD.

cerebri, and the spaces between them and the commissure are the ven-
tricles of the corpus callosum. If a section through the brain is made,
either vertically or horizontally, the white matter is spotted with dots
(the puncta vasculosa), due to the escape of blood from the severed ves-
sels of the medullary substance (Plate 11, Fig. 2, No. 18).

The medullary substance of the cerebrum consists of fine white fibres,
which may be described as longitudinal, transverse, and diverging fibres.
The longitudinal fibres compose the fornix, the strie longitudinales, the
teenie semicirculares, the gyri fornicati, the gyri uncinati, and the
peduncles of the pineal gland. The ¢éransverse fibres connect the two
hemispheres, and are found in the corpus callosum and the anteriér and
posterior commissures. The dwerging (or peduncular) fibres are derived
partly from the crusta and partly from the tegmenta of the crura cerebri,
having originated in the cord and medulla oblongata. Those from the
crusta are derived mainly from the anterior pyramids of the medulla,
receiving en route through the crusta fibres from the gray walls of the
aqueduct of Sylvius and the locus niger, and pass forward and outward
to the internal capsule between the caudate and lenticular nuclei on each
side. They distribute fibres to the nuclei of the corpora striata and
receive others from them, and after issuing from the capsule radiate in
all directions toward the cortical surface of the cerebrum, forming the
corona radiata. Many of the fibres of the crusta have been traced directly
through the internal capsule to the cortex. The so-called pyramidal tract
is composed of such fibres passing to the gray surface-matter of the
ascending frontal and parietal convolutions in the neighborhood of the
fissure of Rolando. Some bundles of the fibres on the outer portion of
the crusta have been traced into the occipital convolutions of the hemi-
spheres, and are known as the direct sensory tracts. The fibres from the
tegmenta are derived from the reticular formation of the medulla oblon-
gata, and are joined by fibres from the superior and middle peduncles of
the cerebellum, and by fibres from the corpora quadrigemina, terminating
apparently in the sub-thalamic region and the optic thalami. Many
fibres from the external portions of the optic thalami have been traced
radiating into the temporo-sphenoidal and occipital lobes. They constitute
THE REGION OF THE HEAD. 59

the radiatio thalami. Besides these there are arcuate or association fibres,
which bring adjacent convolutions into communication.

Much patient and critical study has been given to the unravelling
of the fibres of the medullary structure of the cerebro-spinal system by
anatomists. Briefly stated, the conclusions drawn from their observations
establish that there are three sets of nerve-centres, and three sets of nerve-
fibres through which impressions are transmitted to and from the periphery
and to and from the gray cortical surface of the hemispheres. The nerve-
centres are the gray matter of the cord and medulla oblongata, the optic
thalami and corpora striata, and the cortical surface of the convolutions.
The herve-fibres are those which connect the periphery with the gray
matter of the cord and medulla, those which connect the gray matter of
the cord and medulla with the basal ganglionic centres, the optic thalami,
and the corpora striata, and those which bring these centres into relation
with the cortical surface of the convolutions. The precise function of
the basal ganglionic centres is unknown, but from their relations as
above described it may be inferred that the corpora striata are connected
with motion, and that the optic thalami are connected with sensation. In
both there is crossed action; and the above inference is further empha-
sized by clinical and pathological data, as well as by physiological ex-
periments.

Apoplexy attended by hemorrhage of one of the lenticulo-striate
arteries into the substance of either of the corpora striata is followed by
paralysis of motion of the opposite side of the body, without loss of sensa-
tion; and similar involvement of either of the optic thalami is followed
by loss of sensation in the opposite side, without diminution of power of
motion.

The approximate topographical relation of the anterior limit of the
corpora striata to the external surface of the head may be indicated by
drawing a line on each side from the stephanion to the pterion (Plate
2, Fig. 1). The same relative bearing which the optic thalami, within
the head, probably hold may be mapped out by an anterior vertical line
drawn from the bregma to the external auditory opening on each side,
and a posterior vertical line drawn from the parietal eminence to the
60 THE REGION OF THE EAR.

asterion (Plate 2, Fig. 1). A line drawn from the ophryon backward
on the side of the head to the occiput, through the asterion, will indicate
the position of the lateral ventricle, its anterior limitation corresponding
to a line from the stephanion to the pterion, and its posterior limitation to
a line from the parietal eminence to the asterion, as above described.

The operation of trephining for tapping the ventricles for intra-cranial
hemorrhage is very hazardous, and requires careful consideration of the
position of the corpus striatum and optic thalamus and their relations to the
highly vascular region of the Sylvian fossa and island of Reil, where the
cortical vessels are large and near their origin from the middle cerebral
and internal carotid arteries. If the procedure is attempted, in order to
avoid this important area the best position for the application of the
trephine will be on a line drawn from the ophryon to the lambda, and
midway between the external auditory opening and the asterion. This
will expose the temporo-sphenoidal lobe about the junction of the middle
and inferior temporo-sphenoidal convolutions. A fine trocar passed in a
direction forward and obliquely downward will (in the adult) reach the
corresponding lateral ventricle. If the ventricle be distended with blood
its walls will be reached two and half centimetres, or about an inch, from
the surface. In two instances within the author’s experience where ex-
ploratory tapping was practised, although no benefit was derived from the
operation, no ill effects were noticed, and the autopsies revealed no injury
to the medullary substance even upon microscopic examination.

THE REGION OF THE EAR.

The ear (auris), or organ of hearing, consists of two accessory
portions, the pinna, or auricle, for the purpose of collecting and con-
verging the aérial vibrations to the external meatus, which conducts them
to the middle ear, or tympanum, and the essential portion, the internal
ear, or labyrinth, where the sensation of sound is produced by their ulti-
mate impression upon the auditory nerve.

The pinna, or auricle (Plate 17), projects from the side of the
head, being movably attached to the external auditory opening of the
THE REGION OF THE EAR. 61

temporal bone by the anterior and posterior auricular ligaments, and the
anterior auricular, superior auricular, and posterior auricular muscles.
The anterior ligament connects the front of the pinna to the root of the
zygoma, and the posterior ligament the back of the pinna to the mastoid
process. The anterior and superior auricular muscles (Plate 20, No. 42)
arise from the temporal arch of the aponeurosis of the occipito-frontalis
muscle, and are respectively attached to the front and upper part of
the pinna. The posterior auricular muscle consists of a few fleshy
bundles which arise from the base of the mastoid process and are
inserted into the back of the pinna. These auricular muscles are very
imperfectly developed in man, and consequently the auricle possesses
a limited functional capability, and persons who have been deprived of
it suffer very little loss in their power of hearing. The pinna is
formed of a yellow fibro-cartilage, with some fat and connective tissue,
covered with integument, which is expanded from the side of the head
and very closely adherent to the cartilage. The auricular cartilage is an
incomplete irregular plate presenting many peculiar elevations and con-
cavities. The deficiencies (or fissures of Santorini) in the cartilage are
bridged over by fibrous tissue. The folded border of the pinna is called
the helix (Plate 17, No. 9); the elevation within it, the antiheliz; and
the groove between them is the fossa of the helix (or fossa scaphoidea).
The upper part of the antihelix divides anteriorly and encloses the fossa
of the antihelix (or fossa ovalis). The concha is the deep concavity
leading into the meatus. In front of the concha is the éragus (Plate 17,
No. 18), a conical elevation which is usually covered with some conspic-
uous hairs. Behind the tragus, at the outer part of the concha, is the
antitragus. The tragus and antitragus are separated by a deep notch,
the incisura. Below the concha is the soft pendulous portion of the
pinna, the dobule (Plate 17, No. 16), which consists of fat and fibrous
tissue covered with skin and without any cartilaginous basis. There is
great variability in the development of the auricle, both as to its confor-
mation and as to the manner in which it is set on the side of the head.
The margin of the helix is often irregular and presents a conical process
at its upper part. The skin covering the pinna is thin, with very little
PLATE 9.

Figure

1.

The right side of the head, with the scalp removed to show the topographical survey of the skull in its relations to
the brain. The temporal muscle and its fascia have also been removed to show their ridges.

1. The junction of the coronal and sagittal sutures (the 9.
bregma). 10.

2. The cut edge of the scalp tissues.

3. The parietal eminence. 11.

4. The junction of the lambdoid and sagittal sutures (the

lambda). 12,
5. The position of the junction of the occipital, parietal, 13.

and temporal bones (the asterion).

6. The external occipital protuberance (the inion). 14,

7, The coronal suture.
8. The point where the ridge for the temporal fascia crosses
the coronal suture (the superior stephanion).

Figure

The frontal eminence.

The point of intersection of the ridge for the temporal
muscle and the coronal suture (the inferior stephanion).

The superciliary ridge, covered with the tissues of the
eyebrow (the ophryon).

The top of the squamo-parietal suture.

The junction of the nasal bones with the frontal (the
nasion).

The position of the anterior inferior angle of the pari-
etal bone, and its junction with the great wing of
the sphenoid and frontal and temporal bones (the
pterion).

i

The right side of the head with the skull removed, showing the dura mater and the main branches of the great
meningeal artery. This also illustrates the contiguous relations of the tissues of the scalp to the tables of the skull in
their surgical application, and especially to the operation of trephining. ,

1. The scalp. 9.
2. The pericranium.

3. The epicranial aponeurosis. 10.
4, The outer compact table of the skull.

5. The diploic structure. 11.
6. The inner compact table of the skull.

7, The posterior branch of the great meningeal artery.
8. The dura mater.

The anterior branch of the great meningeal artery and
its vein.

The middle branch of the great meningeal artery and
its vein.

The position of the anterior inferior angle of the pari-
etal bone, corresponding to the root of the great
meningeal artery.
Plate 9 Vout I

 

Copynght/89/by GeoreeMc. Ce.an MD

Dissacted, Photographed and Colored from Nature ty Geowce Mc. Cerin, MD.

Armstrong & Cc. Lith Boston
THE REGION OF THE EAR. 63

subcutaneous tissue, and is closely adherent to the subjacent perichon-
drium, especially within the fosse or concavities. On the helix and the
back of the pinna it is somewhat looser, and may become extremely
swollen and painful from the tenseness produced by inflammation of
the parts, as in erysipelas. There are numerous sebaceous glands within
the scaphoid fossa and the concha. Besides the bands of fibrous tissue
which fill up the breaches in the auricular cartilage, and which are known
as the intrinsic ligaments, there are various small muscles which extend
between the different parts of the cartilage. On the convex surface
toward the side of the head there are some muscular fibres extending
from the concha to the posterior border of the helix, called the trans-
verse auricular muscle, and others from the top of the concha to the top
of the back of the antihelix, called the oblique auricular muscle. On the
outer or concave surface of the concha are the tragicus, consisting of ver-
tical fibres on the front of the tragus, the antitragicus, which is usually
well developed and extends obliquely from the antitragus to the caudate
process of the helix, the helicis major, which ascends along the front part
of the helix from the caudate process to the highest part, where it
begins to curve backward, and the helicis minor, which passes from
the floor of the concha anteriorly to the end of the helix. All these
intrinsic auricular muscles are supplied by branches of the facial nerve.

The arteries supplying the pinna are derived from the posterior
auricular, temporal, and occipital arteries. The veins pass into the tem-
poral vein. The nerves are branches from the great auricular branch
of the superficial cervical plexus, the auriculo-temporal branch of the
inferior maxillary, the posterior auricular branch of the facial, and the
auricular branch (Arnold’s) of the pneumogastric nerve. The latter
especially supplies the concha.

The external auditory meatus is the oval passage which extends
three centimetres, or about an inch and a quarter, obliquely inward and
forward from the concha to the tympanum, conforming to the petrous
portion of the temporal bone. It is a curved oval canal, with the
greatest diameter in the vertical direction at the concha, and in the
transverse direction atthe membrana tympani, which completely closes
64 THE REGION OF THE EAR.

the bottom of the meatus. Owing to the oblique direction of the mem-
brana tympani, the floor of the canal is a little longer than the roof, which
is highest at the middle. The middle of the meatus is also the narrowest
portion, and affords the greatest obstacle to the removal of foreign
bodies from the bottom of the canal. The first twelve millimetres, or
half-inch, of the meatus consists of a tubular continuation of the cartilage
of the pinna, which is firmly connected with the osseous portion, although
it is incomplete at the upper and back part, where the breach is filled in
with fibrous tissue. The cartilaginous portion of the canal may be some-
what straightened by drawing the pinna upward, outward, and backward.
It is lined with integument which contains many sebaceous and ceruminous
glands. The sebaceous glands are often the seat of minute abscesses which
are extremely painful. The ceruminous glands secrete the cerumen or ear-
wax. The osseous portion is two centimetres, or about three-quarters of
an inch, in length, and more constricted than the cartilaginous portion,
being formed by the auditory plate above and by the tympanic plate below.
The auditory plate extends to the tympanum, while the tympanic plate at
its inner end is grooved for the insertion of the membrana tympani. The
upper wall of the osseous portion of the meatus is separated from the cra-
nial cavity, as already stated, by only a thin layer of bone, which is apt to
give way in abscess or bone-disease and occasion meningitis. The anterior
wall is in relation to the condyle of the lower jaw and part of the parotid
gland. The posterior wall separates the meatus from the mastoid cells,
but is so thin a partition that it is liable to break down in mastoid
disease. The inferior wall is very dense, and corresponds to the vaginal
process of the temporal bone. The skin within the osseous portion of
the meatus is very thin and adherent to the periosteum, and contains
no sebaceous glands.

The cerwminous glands resemble in structure hypertrophied sweat-
glands, and are mainly confined to the skin lining the cartilaginous portion,
although a few are placed along the roof of the osseous part of the canal.
The skin at the bottom of the meatus is spread over the membrana tym-
pani, where it forms a cul-de-sac, so that after maceration the pouch of
cuticle may be removed, showing the exact form of the meatus.
THE REGION OF THE EAR. 65

The membrana tympani (Plate 3, Fig. 5, No. 17) is a thin, semi-
transparent, oval membrane inserted obliquely downward and inward in
a bony groove at the termination of the meatus. In children this mem-
brane holds a more oblique position than in the adult, owing to the
imperfect development of the bony walls of the auditory canal. There
is generally, although not always, a deficiency in the upper part of the
groove in which the membrane is attached, called the notch of Rivinus,
which is merely covered by the skin lining of the meatus, and which may
allow the escape of fluid from within the middle ear without perforation
of the membrane. The membrana tympani is less securely attached at
this notch than at the rest of its circumference: therefore when it is sub-
jected to any violent concussion it is liable to give way at this point. The
structure of the membrane is fibrous tissue, with most of the fibres radiating
from the centre, which receives the handle of the malleus and is slightly
drawn inward, so that this portion of the membrane is called the wmbdzlicus.
The membrana tympani is covered on the outer side by the skin lining of
the meatus, as just stated, and upon its inner surface by the mucous lining
of the tympanum. It is supplied by the tympanic branch of the internal
maxillary artery, which enters by the Glaserian fissure, and it receives a
branch from the auriculo-temporal nerve.

The tympanum, or middle ear, is an irregular cavity, within the
petrous portion of the temporal bone, which serves as an air-chamber
between the auditory meatus and the labyrinth or internal ear, having a
communication anteriorly with the pharynx by the Eustachian tube, so
that the atmospheric pressure is equal on both sides of the membrane.
The tympanic cavity (Plate 3, Fig. 5, No. 5) is somewhat broader behind
and above than it is below and in front, and it is traversed by three little
bones, the ossicles, which are movably connected with one another by
ligaments and extend between the membrana tympani and the fenestra
ovalis of the labyrinth, so that they serve to conduct the vibrations across
the tympanum. It is not quite twelve millimetres, or half an inch, long
from before backward, about six millimetres, or a quarter of an inch, in its
vertical direction, and from two to four millimetres, or from one-twelfth to

one-sixth of an inch, in width from its outer to its inner boundaries. The
9
66 THE REGION OF THE EAR.

bony walls of this cavity are very thin, and have important relations to
the neighboring structures. The upper wall, or roof, is a thin bony plate
on the anterior surface of the petrous portion and close to the junction
of the squamous portion of the temporal bone. There is a squamo-
petrosal suture in the roof of the tympanum in infancy which may
admit of inflammation of the lining membrane being transmitted to the
dura mater within the cranial cavity. The floor is a very narrow, delicate
plate of bone, overlying the jugular fossa, and perforated anteriorly by a
small foramen for the tympanic branch of the glosso-pharyngeal (Jacob-
son’s) nerve, which arises from the ganglion of Andersch and eventually
passes out of the tympanic cavity through the upper tympanic canal into
the middle fossa of the cranium, and is known as the lesser superficial
petrosal nerve, whence it passes by the innominate canal in the sphenoid
bone to join the otic ganglion. The outer wall is mainly formed by the
membrana tympani and the margin of the bony groove which accommo-
dates it. The latter has in it three small openings,—viz., the G@laserian
jissure, a little slit at the upper and front part of the bony ring, which
lodges the processus gracilis of the malleus and the so-called laxator
tympani muscle, and gives passage to the tympanic branch of the internal
maxillary artery; the ier postervus, behind the membrana tympani,
which gives entrance to the chorda tympani nerve; and the ier anterius,
which runs parallel with the Glaserian fissure and leads into the canal of
Huguier, giving exit to the chorda tympani nerve. The immner wall is
vertical and very uneven, and presents various objects of interest. At the
upper part is the curved ridge corresponding to the aqueduct of Fallopius
(Plate 3, Fig. 5, No. 9), which accommodates the facial nerve. Just below
this is the fenestra ovalis, which communicates with the vestibule of the
internal ear, but in the recent state is filled with a membrane to which
is attached the base of the stapes. Below this is the promontory, which
corresponds to the first turn of the cochlea, and is slightly grooved for
the branches of the tympanic plexus of nerves. Below and posterior to
the promontory is the fenestra rotunda, which is an opening at the bottom
of a conical depression leading to the scala tympani of the cochlea, but
in the recent state is closed by a membrane (the membrana tympani
THE REGION OF THE EAR. 67

secundaria). The conical eminence in front of the ridge of the aqueduct
of Fallopius and behind the fenestra ovalis is called the pyramid. It is
hollow, and contains the stapedius muscle, the little round tendon of which
passes through a foramen in the apex to be inserted into the stapes. The
posterior wall is perforated by openings of various sizes leading into the
cellular spaces within the mastoid process, which are lined with the same
mucous membrane as the cavity of the tympanum, and are mostly filled
with air. Owing to the contiguity of structure, the mastoid cells are
often involved in suppurative disease of the middle ear; their proximity
to the lateral sinus has already been referred to (page 6).

The anterior wall of the tympanum is very thin, and in direct relation
with the carotid canal, from which it receives the tympanic branch of
the internal carotid artery. At its upper part is an opening in a conical
eminence which transmits the tendon of the tensor tympani muscle.
This eminence is sometimes called the anterior pyramid. A bony septum
separates it from the channel which conveys the air from the pharynx
into the tympanum, the Hustachian tube. This channel begins near the
processus cochleariformis in the lower part of the anterior wall, and runs
for twelve millimetres, or about half an inch, to the angle of juriction
‘of the petrous and squamous portions of the temporal bone, where it
has a rough, jagged extremity to which is attached a cartilaginous con-
tinuation two and a half centimetres, or about an inch, in length. The
mucous lining of the tympanum is continued through the Eustachian tube
to its pharyngeal opening, which is behind the inferior meatus of the
nose (Plate 12, No. 32) and in close relation with the tonsil gland.

The ossicles which extend across the tympanum are the malleus
(or hammer), the incus (or anvil), and the stapes (or stirrup), which are
articulated to one another by ligamentous bands and so arranged that they
serve to render the membrana tympani tense or loose according to the
degree of impulse of the vibrations. The malleus consists of a head,
which is attached by a suspensory ligament to the roof of the tympanum
and articulates with the incus posteriorly; a neck, the constriction below
the head, tapering into the manubrium (Plate 3, Fig. 5, No. 14), to
be fastened to the fibrous portion of the tympanic membrane along its
68 THE REGION OF THE EAR.

upper part, as far as the umbilicus, as already described; the processus
gracilis, a very long delicate projection from a tubercle below the neck,
extending into the Glaserian fissure and receiving the insertion of the
ligamentous band formerly called the laxator tympani muscle; and the
processus brevis, a slight elevation at the root of the manubrium, resting
upon the membrana tympani and receiving the insertion of the tensor
tympani muscle. The incus is shaped somewhat like a bicuspid tooth
with widely separated unequal fangs. The body of the incus has a glenoid
depression for the reception of the head of the malleus. The long process
(Plate 3, Fig. 5, No. 16) is placed nearly parallel with the manubrium
of the malleus, and articulates with the head of the stapes. The short
process extends backward to be fixed in the neighborhood of the mastoid
openings. The stapes is a beautifully constructed little bone very closely
resembling a miniature stirrup. The neck is a constriction just below
the point where the head is connected with the long process of the incus,
and it receives the insertion of the tendon of the stapedius muscle after
it comes through the posterior pyramid. The dase is the oval plate of
bone, at the opposite ends of the delicate bony crura, which rests upon a
membrane covering the fenestra ovalis, and thus completes the bony chain
and serves to convey the impulse of the vibrations upon the membrana
tympani to the fluid within the vestibule of the internal ear. Besides the
ligamentous bands which support the ossicles and retain them in position,
there are capsular bands at the articulations between the malleus and the
incus, and between the incus and the stapes. The amount of motion
between these little bones is very slight, and is produced by the various
actions of the tensor tympani and stapedius muscles. The éensor tympani
muscle arises from the apex of the petrous portion of the temporal bone
and from the cartilaginous portion of the Eustachian tube, being lodged
within a special canal above the latter, and is inserted into the handle
of the malleus. It.is supplied by a nerve from the otic ganglion, in rela-
tion to the internal maxillary artery, and by drawing the head of the mal-
leus inward renders the membrana tympani tense.

The stapedius muscle arises from the hollow of the posterior pyramid,
and its tendon, which is supplied with a synovial sheath, is inserted into
THE REGION OF THE EAR. 69

the neck of the stapes. It receives a little branch from the facial nerve,
which comes through an opening in the adjacent aqueduct of Fallopius,
and the action of the muscle probably serves to increase the tension upon
the fluid within the vestibule. The mucous lining of the tympanic cavity
is closely attached to the periosteum, except where it is pierced by the
vessels and nerves, and is reflected over the membrames which fill in the
bottom of the meatus and the fenestra ovalis, and completely surrounds
the ossicles. It has been already stated that the mucous lining is con-
tinuous from the pharynx by the Eustachian tube and is prolonged into
the mastoid cells. The mucous lining is supplied with filaments from
the tympanic plexus of nerves.

The facial nerve (or seventh cranial nerve) enters the internal audi-
tory meatus in the apex of the temporal bone, and, after interchanging
a few fibres with the auditory nerve within the meatus, enters the aque-
duct of Fallopius, which is a tortuous canal in the upper and posterior
margin of the inner wall of the tympanum above the fenestra ovalis,
and at the back of the tympanic cavity passes vertically downward to the
stylo-mastoid foramen. The facial nerve within the aqueduct presents a
gangliform swelling (intwmescentia gangliformis) in the neighborhood of
the hiatus Fallopii, which is an oblique slit in the anterior border of the
petrous part of the temporal bone, giving passage to the large petrosal
nerve, which, combining with the sympathetic branch from the carotid
plexus, forms the Vidian nerve, and thus brings the facial nerve in rela-
tion with the spheno-palatine (Meckel’s) ganglion (Plate 3, Fig. 2, No. 6).
From the gangliform swelling also arise the small petrosal nerve and the
eaternal superficial petrosal nerve,—the former passing to the otic ganglion
and the latter to the sympathetic plexus around the middle meningeal
artery. The tympanic branch of the facial nerve, as already stated, passes
through a foramen in the descending part of the aqueduct to enter the base
of the posterior pyramid to supply the stapedius muscle. In this vicinity
the facial nerve receives a communicating filament from Arnold’s nerve.
Between this point and the stylo-mastoid foramen, where the facial nerve
makes its exit from the skull, an important branch, the chorda tympani
nerve (Plate 3, Fig. 2, No. 24), passes upward in a bony channel parallel to
PLATE 10.

Figure 1.

The dura mater removed to show the vessels of the pia mater over the cortical surface of the right hemisphere.

1. The cut tissues of the scalp.
2. The pia mater enveloping the outer surface of the right

ly

or wh

wo

10.
11.
12.

14,

hemisphere, and showing the complexity of the
course of the external cerebral veins and arteries,
which mask the underlying convolutions.

8. Section of the skull-cap.

Figure 2.

The pia mater removed from the right hemisphere to show the surface-markings of the fissures and convolutions,
and a topographical survey of the subdivisions of the motor area of the opercular region, according to the most recent
investigations of the localization of the centres of function of the cortical surface of the cerebrum.

The centre for the movements of the face (the expres-
sions).

. The centre for the movements of the fingers.

. The centre for the movements of the thumb.

. The centre for the movements of the wrist.

. The centre for the movements of the shoulder and

elbow.
The centre for the movements of the hip, knee, and
leg.

. The centre for the movements of the foot and toes.
. The cut tissues of the scalp.
. The fissure of Rolando (in this case joining the hori-

zontal branch of the fissure of Sylvius).
The calloso-marginal fissure.
The superior parietal convolution.
The inter-parietal fissure.

. The inferior parietal convolution.

The ascending parietal convolution.

 

15.
16.
17.
18.
19.
20.
21.

22.
23.
24,
25.
26.
27.
28.
29.
30.
31.

The angular convolution.

The parieto-occipital fissure.

Section of the skull-cap.

The superior occipital convolution.

The superior temporal fissure.

The middle occipital convolution.

The centre for the movements of the lips, tongue,
throat, and larynx.

The speech centre.

The superior frontal convolution.

The posterior frontal fissure.

The ascending frontal convolution.

The middle frontal convolution.

The inferior frontal convolution.

The ascending branch of the fissure of Sylvius.

The horizontal branch of the fissure of Sylvius.

The fork of the fissure of Sylvius.

The superior temporal convolution.

N. B.—The figures on Plates 9 and 10 were taken in succession from the head of an adult male, in remarkable physi-
cal health, and represent the structures in their normal condition and position. Comparison of the series will demon-
strate the perplexities attending the study of cerebral localization, and the parts to be encountered in cerebral surgery.
oe

Plate 10

 

Dissacted, Photographed and Colored from Nature by Georse Mc.

Crescan, MO,

Copyright/890,by GEORGE Me Cuew.an, MD.

Wore, 1

Armstrong £.Co Lith Boston
THE REGION OF THE EAR. 71

the aqueduct and enters the cavity of the tympanum through a foramen
(the iter posterius) below the posterior pyramid and close to the membrana
tympani. It is surrounded with the mucous lining of the tympanum, and,
passing between the manubrium of the malleus and the long process of
the incus, it emerges through a foramen (the iter anterius), the opening
of a special bony canal (the canal of Huguwier), close to the Glaserian
fissure. Thence it descends between the two pterygoid muscles, behind
the middle meningeal artery and in close relation to the auriculo-temporal
and inferior dental nerves, and blends with the lingual branch of the
inferior maxillary nerve, being eventually distributed to the submaxillary
ganglion and the lingualis muscle. The chorda tympani nerve is generally
believed to originate from the nerve of Wrisberg, intermediate between
the auditory and facial nerves. Owing to its comparative distribution in
the lower animals, it is supposed to preside over the sense of taste at
the anterior portion of the tongue. Recently this nerve has been traced
through the geniculate ganglion of the facial nerve to the fourth ventricle,
and it is therefore considered as an independent cranial nerve, with the
special function concerned in the power of speech (Sapolini).

The facial nerve communicates in the temporal region by filaments
with the pneumogastric, the glosso-pharyngeal, the great auricular, and
the auriculo-temporal nerves, and with the carotid plexus; and on the
face with the numerous sensory branches from the trifacial nerve. A
lesion of the facial nerve within the aqueduct of Fallopius from fracture
of the base of the skull is attended by paralysis of the facial muscles,
which is often a diagnostic feature of such an injury in connection with
other symptoms.

The tympanum is very richly supplied with blood by little arteries
from various sources. The tympanic branches of the internal maxillary
and internal carotid arteries, the petrosal branch from the middle menin-
_ geal artery, and minute branches from the ascending pharyngeal artery,
enter from the front, while from behind the stylo-mastoid branch from
the posterior auricular artery penetrates by the aqueduct of Fallopius.
The veins empty into the superior petrosal and lateral sinuses, and into
the middle meningeal and pharyngeal veins.
72 THE REGION OF THE EAR.

The internal ear, or labyrinth, consists of a very complex arrange-
ment of spaces and channels in the most compact part of the temporal
bone. There are three special compartments, known as the vestibule,
the semicircular canals, and the cochlea. The vestibule is an irregular
oblong cavity situated between the tympanum and the internal auditory
meatus, having the fenestra ovalis on its outer wall, by which it com-
municates with the tympanum when the parts are macerated, but in the
recent state it is closed by the base of the stapes and its annular liga-
ment, and on its inner wall there is a shallow depression in front, called
the fovea hemispherica, the lower part of which, the macula cribrosa, is
perforated by numerous foramina for the transmission of the filaments
of the auditory nerve. Behind the fovea hemispherica there is the crista,
a ridge, with usually a little’ opening, called the aqueduct of the vestibule,
which gives passage to a small vein. In the roof of the vestibule there is
a depression, the fovea hemi-elliptica, which lodges the utricle. The five
openings of the semicircular canals are in the posterior part of the vesti-
bule, and anteriorly there is the opening into the cochlea: so that the
vestibule is the common cavity in which all the others communicate. The
semicircular canals are three bony canals above and somewhat behind the
vestibule. Each canal forms about two-thirds of a circle; and they differ
in their directions, so that they are called superior, posterior, and external.
Each canal is dilated at one end,—the ampulla,—corresponding to a similar
dilatation of the membranous lining of the labyrinth. The canals all
open into the posterior part of the vestibule by both of their extremi-
ties, but, as one of the openings is made up of the extremities of two
of the canals, there are only jive distinct openings.

The superior semicircular canal is vertical in direction, and arches
across the anterior part of the petrous portion of the temporal bone;
forming a rounded elevation on its surface. Its outer ampullated extremity
opens into the upper part of the vestibule. Its non-ampullated extremity °
opens into the back of the vestibule by a common orifice with the similar
extremity of the posterior semicircular canal. The latter is also vertical,
but is placed at a right angle with the superior canal, being parallel to the
posterior surface of the petrous bone. It is the longest of the three canals.
THE REGION OF THE BAR. 73

The eaternal semicircular canal is placed horizontally, and is the shortest.
The cochlea closely resembles a common snail’s shell, and is placed almost
horizontally at the anterior part of the labyrinth. Its base corresponds
to the bottom of the internal auditory meatus, and is perforated by the
cochlear branches of the auditory nerve. Its apex is in relation with the
upper and front part of the inner wall of the tympanum. The cochlea
consists of a conical-shaped central axis, the modiolus, and a gradually
tapering spiral canal which winds round the modiolus to the extent of
two and a half turns, terminating at the apex of the cochlea in a little
dome,—the cupola. ,
The modiolus (or columella) is quite thick at its base, but gradually
diminishes toward the apex, where it terminates in the imfundibulum.
Its interior is composed of cancellous bone, through the meshes of which
vessels and nerves pass to the spiral lamina. The arteria centrals modioli
is a little artery which is accommodated in a canal within the centre of the
modiolus. The spiral canal is subdivided by a delicate plate, the lamina
spiralis, partly bony (the lamina ossea) and partly membranous (the
membrana basilaris), into two parallel tubes, called the scale. The scala
tympani is the larger and lower of these tubes, and is in relation with
the tympanum by the membrane attached to the fenestra rotunda; the
scala vestibuli is the upper tube, and is in direct connection with the ves-
tibule. Owing to a deficiency in the top of the modiolus, the two scale
communicate with each other in the cupola by the opening called the
helicotrema, which is partly bounded by a hook-shaped process at the end
of the lamina (ossea) spiralis. The scala vestibuli is furthermore sub-
divided by the oblique membrane of Reissner, which separates a portion
of its upper part from the rest and thus forms the scala media, or cochlear
canal. At the junction of the bony lamina with the modiolus there is a
very small winding canal, the canalis spiralis modioh, which is occupied
by an enlargement of the cochlear nerve, whence the nerves pass to the
organ of Corti. The agueductus cochlee is a small aperture leading to
a canal which opens on the basilar surface of the petrous bone and trans-
mits a vein from the cochlea to the internal jugular vein. The mem-

branous continuation of the osseous lamina spiralis is thickened into an
10
74 THE REGION OF THE EAR.

elevation, the limbus, or denticulate lamina, which overhangs the furrowed
margin (the sulcus spiralis) of the bony lamina. The upper border of
the sulcus is called the labiwm vestibulare, the lower, the labiwm tympani-
cum. From the latter a delicate membrane (the membrana basilaris)
extends to the outer bony wall of the cochlea, completing the scala
tympani. Where the basilar membrane is attached to the outer wall
there is a projection of connective-tissue cells,—the so-called ligamentum
spirale. The basilar membrane increases proportionately as the osseous
jamina decreases toward the cupola. The membrane of Rerssner is the
oblique membrane which partitions off the cochlear canal from the scala
vestibuli. It is a very delicate layer of connective tissue, covered on the
cochlear surface with epithelium, and is continuous with the periosteum
lining the upper surface of the lamina spiralis. The cochlear canal is
formed on its inner wall by the membrane of Reissner, on its outer wall
by the periosteum, on its lower wall by the limbus spiralis and the basilar
membrane. Within the periosteum on the outer wall there is a conical
eminence of connective tissue which accommodates a tiny vein,—the vas
spirale. Between this and the attachment of Reissner’s membrane there
is another eminence, which consists of numerous anastomosing vessels,—the
strie vascularis.

The basilar membrane sustains the complex and wonderful arrange-
ment of the organ of Corti, upon which the ultimate filaments of the
auditory nerves are distributed. The organ of Corti is covered over
by the membrana tectoria, which is a fine layer of connective tissue
extending between the labium vestibulare of the osseous lamina and the
attachment of Reissner’s membrane and placed parallel to the basilar
membrane. The entire osseous labyrinth is lined with a very thin perios-
teum, which consists of fibro-elastic tissue with cell-elements and serves
as a matrix for blood-vessels. From this tissue is secreted a small
quantity of fluid known as the perilymph, or hquor Cotunnii, which
surrounds and suspends the membranous labyrinth, a tubular reproduction
of the osseous labyrinth, which also encloses a little fluid, the endolymph,
or liguor Scarpe. The membranous labyrinth receives the distribution of
the terminal filaments of the auditory nerves, which, owing to their inter-
THE REGION OF THE EAR. 7)

position between the two fluids, are thus rendered susceptible to the most
delicate vibrations. The vestibular portion of the membranous labyrinth
forms two unequal communicating sacs, the utricle and the saccule. The
utricle is lodged, as previously stated, in the fovea hemi-elliptica, and com-
municates with the openings of the semicircular canals. It is the larger
of the two pouches, and is thickest (the macula) at the crista, where
the nerve-branches enter. The saccule rests in the fovea hemispherica
in front of the utricle. It is connected with the cochlear portion of the
membranous labyrinth by the canalis rewniens, and in a roundabout way
with the utricle by the aqueduct of the vestibule, thus establishing an
uninterrupted channel for the endolymph throughout the membranous
labyrinth.

On the inner walls of the utricle and saccule there are many minute
concretiolis of carbonate of calcium which seem to be in connection with
the ends of some of the nerves. They are called otoliths (or ear-stones).

The membranous semicircular canals correspond to the bony canals
which contain them. They are connected at their ampullated extremities
by the vessels and nerves to the contiguous. periosteum, but in the rest of
their extent they are only about one-third of the diameter of the osseous
canals. The connection at the ampullated extremities with the periosteum
forms a partial septum, the crista acoustica. The membranous structure
consists of three layers, an outer fibrous layer, a middle, the tunica pro-
pria, and an inner or epithelial layer. In the ampullated portions the
epithelial layer presents spindle-shaped cells with ciliated processes, the
auditory havrs.

From the description already given of the relations of the membrane
of Reissner, the basilar membrane, and the membrana tectoria within the
scala vestibuli of the cochlea, it will be seen that they serve practically to
constitute a shrunken membranous cast of the bony cochlea, resembling
in a measure the membranous pouches within the vestibule and the semi-
circular canals. This membranous cochlea, or cochlear duct, is the scala
media above mentioned: it commences opposite the promontory of the
tympanum, and, after winding along the middle of the cochlear canal,
ends at the cupola in a closed extremity. It is connected with the mem-
1

2:
3.

na

OT

i.

Re

PLATE lI.
Figure 1.

Transverse (coronal) section through the head just in front of the ears, passing through the basilar part of the occip-
ital bone below and the bregma above. Showing the section of the brain, in situ, at the middle of the lateral ventricles.
The figure represents the parts as seen from the front.

. Section of the superior longitudinal sinus of the dura

mater, showing its triangular shape.

The cut tissues of the scalp.

The diploic structure, between the outer and inner
tables of the skull.

. The dura mater over the right cerebral hemisphere.
. The gray involuted cortical substance of the brain.
. The white medullary substance of the brain, showing

puncta vasculosa.

. Section of the inferior longitudinal sinus of the dura

mater, showing its oval shape.
The corpus callosum.
The fornix.

. The right lateral ventricle.

. The right fissure of Sylvius.

. The internal capsule.

. The external capsule.

. The right optic thalamus.

. The basilar artery on the pons Varolii.
. The right ear.

. The osseous portion of the right Eustachian tube.
. The right internal carotid artery.

. The right parotid gland.

. The right internal jugular vein.

 

21. The right pneumogastric nerve.

22

. The right longus colli muscle.

23. The first frontal convolution. ‘

24. The falx cerebri, in the longitudinal fissure.
25. The second frontal convolution.

26. The third frontal convolution.

27. The left lateral ventricle.

28, The internal capsule.

29
30.

. The left fissure of Sylvius.
. The external capsule.

31. The left optic thalamus.
82, 38, and 34. First, second, and third temporal convolu-

35

tions.
. The pons Varolii.

86. The basilar portion of the occipital bone.

37
38
39.

. The osseous portion of the left Eustachian tube.
. The left ear.
. The left parotid gland.

40. The left pneumogastric nerve.
41. The left internal carotid artery.
42, The left internal jugular vein.

43
44

. The left longus colli muscle.
. The pre-vertebral fascia,

Figure 2.

Horizontal section of the head, with the brain in position, showing the lateral ventricles and adjacent parts.

. The position of the foramen cecum.
. The anterior median fissure (or fore part of the longi-

tudinal fissure).

. The anterior cornu of the left lateral ventricle.
. The intra-ventricular portion of the left corpus striatum

(or the nucleus caudatus).

. The position of the foramen of Monro.
. The extra-ventricular portion of the left corpus stria-

tum (or the nucleus lenticularis).

. The left optic thalamus.

. The left portion of the choroid plexus.

. The splenium of the corpus callosum.

. The posterior cornu of the left lateral ventricle.

. The posterior median fissure (or hind part of the longi-

tudinal fissure).

12
13.
14.
15.

. The frontal sinus of the skull.

. The frontal lobe of the brain, with puncta vasculosa.

. The anterior cornu of the right lateral ventricle.

. The intra-ventricular portion of the right corpus stria-
tum (or the nucleus caudatus).

16, The extra-ventricular portion of the right corpus stria-

tum (or the nucleus lenticularis).

17. The right optic thalamus.

18,
19
20.
21

. The fornix.

. The right portion of the choroid plexus.

. The middle cornu of the right lateral ventricle.

. The posterior cornu of the right lateral ventricle.

22, The point where the longitudinal sinus terminates at

the torcular Herophili.

Figure 3.

Antero-posterior section of the head, with brain in position, through the middle of the right hemisphere. The
orbital muscles are’seen in relation to the eyeball.

Section through the fissure of Rolando.

2. The occipito-parietal fissure.
8. The corpus callosum.

4.
5:
6

The corpus striatum.

. The optic thalamus.

. The velum interpositum.
7. Position of the fourth ventricle.

8. The transverse fissure, with the tentorium cerebelli.
9.
0
1

The arbor vitee of the cerebellum.

. The inion.
. The frontal lobe of the right hemisphere.

12
13

. The frontal sinus.
. The superior rectus muscle.

14. The right eyeball.
15. The external rectus muscle.

16

H

18,
19,
20.

. The capsule of Tenon.

7. The right optic nerve.

. The inferior oblique muscle.
. The inferior rectus muscle.
. The temporo sphenoidal lobe.

21. The antrum of Highmore, in the right superior max-

illary bone.

N. B.—The heads from which all of these figures were taken were very recent and without any hardening prepara-
tion, so that the relations of the parts are perfectly preserved. (Figs.1 and 2 are from male heads, about thirty and
thirty-five years of age,and Fig.3 from a female aged thirty-seven years.)
Peer . ve

 

 

 

 

 

Copyright, 1831. by Georce Mc Cueitan, MU

Dissected Photographed and Lolorea trom Nature %y Georce Mc, Crettan, M 2.
Armstrong # Co Lith Boston

 
THE REGION OF THE HAR. v7

branous semicircular canals by the ductus reuniens, and is bathed without
by the perilymph and within by the endolymph, like the rest of the mem-
branous labyrinth. It is much more important, however, as it differs
greatly in the character and arrangement of the complex structures con-
tained within a portion of its space, which are known as the organ of
Corti. This organ presents a slight elevation upon the basilar membrane,
and appears to be a modification of the lining epithelium following the
spiral turns of the membrane throughout its course, whence it was
formerly called the papilla spiralis acoustica. Microscopic examination
demonstrates that it consists of a peculiar arrangement of cells which bear
a remarkable similarity to the key-board of a piano-forte. The central
cells are rod-like bodies, the rods of Corti, which are disposed on the basilar
membrane in two sets, an inner and an outer, in such a manner that
they incline toward each other, blending at their upper extremities, forming
a series of arches, the minute spiral space so enclosed by them being the
tunnel of Corti. Both the outer and the inner rods are similar in structure
and have a broad nucleated base, but they differ materially in shape, the
outer being compared to a swan’s head, which is received into the sigmoid
cavities of several of the inner rods, which are in shape very like the
upper extremity of the human ulna. There are a great many more inner
rods than outer, and they are shorter and less obliquely placed. There
are numerous stiff ciliated processes in relation to the inner and outer
rods, called respectively the inner and outer acoustic hair cells. The
acoustic hair cells are believed to be in direct connection with the ultimate
fibrils of the cochlear nerves; and the intervals between them and the
outer rods are occupied by long fusiform cells, the supporting cells of
Deiters, which rest upon the basilar membrane. There is a net-like mem-
brane, the lamina reticularis, spread out over the summits of the outer hair
cells, through which the ciliated processes project. ‘This net-work consists
of several rows of plates, or phalanges, which dovetail with the phalangeal
processes from the summits of the supporting cells. There is a some-
what similar reticular membrane over the ends of the inner hair cells.
The auditory nerve (or eighth cranial nerve) enters the internal audi-
tory meatus (Plate 8, Fig. 1) with the facial nerve and auditory artery,
78 THE REGION OF THE EAR.

and at its bottom passes through a perforated plate, the lamina cribrosa,
to be distributed to the labyrinth, or internal ear, being divided into the
vestibular and cochlear nerves. The facial nerve pursues an independent
course along the aqueduct of Fallopius, as already described (page 69).

The vestibular nerve becomes at first slightly enlarged, and then divides
into various branches, which proceed to the utricle, the saccule, and the
ampulle of the semicircular canals. The cochlear nerve immediately
within the lamina cribrosa separates into numerous filaments, which enter
the canals in the base of the modiolus. Thence they pass outward between
the plates of the osseous lamina, through the ganghon spirale, to form a
minute plexus, the ultimate filaments of which appear to be connected with
the inner and outer hair cells of the organ of Corti.

The labyrinth is: supplied by the auditory artery;“a branch of the
basilar artery (Plate 5, Fig. 3) which accompanies the auditory and facial
nerves into the internal auditory meatus and divides into vestibular and
cochlear branches. These branches correspond to the nerves and ramify
over the periosteal lining of the internal ear, receiving branches of com-
munication from the vessels of the’ tympanic cavity and from the stylo-
mastoid artery, which arises from the posterior auricular branch of the
external carotid artery.

In fractures involving the petrous portion of the temporal bone,
attended with hemorrhage from the external auditory meatus, the source
of bleeding is more generally from the minute arteries of the labyrinth
and the tympanum than from the adjacent internal carotid artery or the
internal jugular vein, laceration of either of which would be probably
immediately fatal. The escape of cerebro-spinal fluid by the same exit is
indicative of a fracture implicating the internal auditory meatus (page 7).
The pressure of this fluid upon the perilymph within the labyrinth, to
which have been attributed some cases of deafness, does not anatomically
exist, as the only lymph-extension is by the sheaths of the auditory vessels
and is too inconsiderable to admit of any degree of pressure by any amount
of intra-cranial effusion.

The auditory vein receives its blood from the veins of the labyrinth,
and, passing out through the internal auditory meatus, empties it into the
THE ORBITAL REGION AND THE EYE. 79

inferior petrosal sinus. There are also emissary veins from the cochlea
and vestibule, which, passing through their respective aqueducts, terminate
generally in the internal jugular vein.

THE ORBITAL REGION AND THE EYE.

The orbits (Plate 28) are two cavities, one on each side of the upper
part of the face, for the lodgement and protection of the eyeballs and their
accessory apparatus. Each orbit is formed of the plane surfaces of the
contiguous bones of the head and face, peculiarly disposed so that the eye
is insured extensive range of vision. These cavities are pyramidal, their
bases corresponding to the surface-margins, and their apices extending
backward and inward in such a manner that their axes continued back-
ward would meet over the body of the sphenoid bone where the optic
commissure rests. The roofs of the orbits are formed anteriorly by the
vaulted orbital plates of the frontal bone and posteriorly by the lesser
wings of the sphenoid bone. The floors are formed chiefly by the orbital
processes of the superior maxille, with the orbital processes of the malar
bones anteriorly and the orbital surfaces of the palate bones posteriorly.
They are much less concave than the roofs. The inner walls are nearly
vertical and parallel with each other, while the outer walls are divergent.
The inner walls are mainly formed by the ossa plana of the ethmoid bone
and the orbital surfaces of the lachrymal bones, with portions of the
sphenoid behind and the nasal processes of the superior maxille in front.
The outer walls are formed anteriorly by the orbital processes of the
malar bones and posteriorly by the orbital plates of the great wings of the
sphenoid bone. At the apices of the orbits the optic foramina transmit
the optic nerves and ophthalmic arteries. External to the optic foramen
at the back part of the outer wall of each orbit is the oblique sphenoidal
fissure, between the greater and lesser wings of the sphenoid bone, which
transmits the ophthalmic division of the trifacial nerve and the nerves to
the muscles of the eyeballs (Plate 3, Fig. 2), together with the ophthalmic
vein and some sympathetic filaments from the carotid plexus. Continu-
ous with the sphenoidal fissure passing externally in the floor of each
80 THE ORBITAL REGION AND THE EYE.

orbit is the spheno-mazillary fissure, which in the recent state is bridged
over by membrane. From the middle of the spheno-maxillary fissure
in the floor of each orbit there extends outwardly a groove which leads
into the infra-orbital canal and gives passage to the infra-orbital nerve
and infra-orbital artery. Just within the nasal margin of each orbit
is the lachrymal fossa, formed by the apposition of grooves in the nasal
process of the superior maxilla and the lachrymal bone. This fossa is the
opening into the nasal duct, which conveys the tears into the .inferior
meatus of the nose. In the sutural line between the ethmoid and frontal
bones there are two foramina, the anterior and posterior ethmordal, the
former transmitting the nasal nerve and anterior ethmoidal vessels and the
latter the posterior ethmoidal vessels. The facial opening into each orbit
is provided with a somewhat four-sided margin, peculiarly adapted above
for the support of the eyebrows and at the circumference for the attach-
ment of the eyelids. The external angular processes of the orbits are the
outer limits of the superciliary ridges at the junction of the frontal
with the malar bones. They are superficial, and important topographical
landmarks, as has been previously stated. Two and one-half centimetres,
or about an inch, from the external angular processes inward toward the
nose, on the borders of the orbital arches there are notches or foramina for
the exit, upon the forehead, of the supra-orbital vessels and nerves. The
bones forming the floor, the inner wall, and the roof. of the orbital cavity
are very fragile, the frontal portion of the roof being often only membra-
nous, so that foreign bodies thrust into the orbit may readily penetrate
downward into the antrum, inward into the ethmoidal cells, or upward into
the cranial cavity. Owing to this latter feature, in abscess of the frontal
lobe of the brain it is feasible to make an artificial opening for drainage
either through the orbit or through the nasal cavity.

The eyebrows (supercilia) consist of the arching folds of the in-
tegument connected beneath with the constrictor muscles of the eyelids,
the orbicularis palpebrarum and occipito-frontales muscles, and especially
the transverse fibres of the orbicularis known as the corrugator muscles
(Plate 15, No. 22). They surmount the superciliary ridges of the frontal
bone, supporting short, thick hairs which at the nasal side of the arch are
THE ORBITAL REGION AND THE EYE. 81

‘directed upward and forward, and for the rest of the arch upward and
outward with increasing obliquity.

Below the eyebrows the skin is of very delicate texture, entirely
destitute of fat, and spread over the elliptical folds, the eyedids, which
consist of the so-called tarsal cartilages, attached to the margin of the
orbit by the palpebral ligaments, and covered by the extremely thin
inner layer of pale fibres of the orbicularis muscle, which are connected
by loose cellular tissue to the skin. So exceedingly thin and delicate is
the covering of the upper eyelid that when it is closed over the eye not
only can its blood-vessels be readily seen, but, owing to the translucency
of the tissues, often the iris may be distinguished through them. Occasion-
ally there is a cutaneous fold from the upper lid overlapping the inner
canthus. The laxity of the cellular tissue of the eyelids is manifest in
the cedematous conditions following inflammation or contusion. The skin
over the lids is wrinkled transversely, and on the upper lid there is a
constant fold which marks the part covering the globe of the eye from
that in relation to the soft structures of the orbit. The furrow which
exists between the lower lid and the cheek deepens in old age and in many
wasting diseases, and produces a peculiar sunken look about the eyes
common to those conditions. The upper lid is larger and more movable
than the lower. It is mainly by the action of the levator palpebree muscle
upon the upper lid that the eye is exposed, and by that of the orbicular
muscle that the eye is closed. The interval between the two lids, the jisswra
palpebrarum or rictus oculi, terminates in the inner and outer corners
or canthi. The size of the rictus varies with the relation of the lids to the
eyeball, according as the eyes are directed upward, forward, or downward.
When the eye is looking upward (Plate 53, Fig. 1), the rictus is dilated,
the upper lid arching as high as the upper margin of the cornea, while a
portion of the white sclerotic coat is visible above the lower lid. When
the eye is looking straight forward, the upper lid slightly covers the
top of the cornea, and the lower lid is on a level with its lower border.
When the eyes are downcast, the upper lid covers the cornea as far as the
top of the pupil, and the lower is on a line with the lower border of the

cornea. The lower lid holds the latter relation also in ordinary closure of
u
82 THE ORBITAL REGION AND THE EYE.

the eyes. The cartilage of the upper lid is larger than that of the lower
one, broad in the middle and narrower at each end, while the lower is
nearly uniform throughout. These cartilages are attached to the orbital
margin by the palpebral ligaments, which are continuations of the perios-
teum lining the orbit. The attachment of the cartilages to the malar
portion of the orbit is by the eaternal palpebral hgament, and that to
the nasal process of the superior maxilla is by the «dernal palpebral
ligament, or tendo oculi (Plate 15, No. 25). The latter is a fine, short
cord at the inner canthus, which passes from its attachment in front of the
lachrymal groove horizontally outward and divides into separate portions
for the palpebral cartilages. The angular artery and vein are on the
inner side of this tendon (Plate 18, No. 3). . The orbicularis palpebrarum
is the sphincter muscle surrounding the eyelids. It’ is attached to the
tendo oculi and the inner and lower margin of the orbit, while above its
fibres blend with those of the occipito-frontalis, and on the cheek with
the elevators of the upper lip and nose, and the zygomatici (Plate 15).
The fibres of this muscle form oval loops round the eyelids and orbit,
the orbital fibres being thicker and redder than those over the eyelids,
as already mentioned. Forced contraction of the orbicular muscle serves
to push back the eye into the orbit, and affords a soft protective pad
in front of it. In winking it is only the palpebral portion of the muscle
which contracts. This momentary closure of the lids is accompanied by
a slight drawing inward at the inner canthus, which directs the tears
toward the puncta lachrymala. The “crow’s-feet” of old age are the
permanent radiating wrinkles produced by the orbital fibres drawing the
brows down and the lower lids up.

The corrugatores supercilua muscles (Plate 15, No. 22) are deep acces-
sory portions of the orbicular muscles, which arise from the internal angular
processes of the orbits, and, passing transversely outward, are inserted into
the superficial muscular fibres and skin of the eyebrows. These bunches
of fibres have special branches from the facial nerves, by their action
wrinkle the forehead vertically, and are the proper muscles of frowning,

The levatores palpebrarum muscles arise from the lesser wings of the
sphenoid bone in the back parts of the orbital cavities, above the optic
THE ORBITAL REGION AND THE EYE. 83

foramina. They pass over the globes of the eyes, terminating in broad
thin tendinous insertions at the tarsal cartilages of the upper lids beneath
the palpebral ligaments. They are constantly in action when the eyes
are open, becoming relaxed in sleep.

The free margins of the eyelids are the thickest parts of the tarsal
cartilages. They are straight, and when the eyes are closed are in accurate
apposition. Upon their edges the eyelashes (cilia) are arranged in several
rows. The lashes of the upper lids are longer and more numerous than
those of the lower lids, and the upper ones curve upward, while the lower
curve downward. The bulbs of the lashes are placed between the tarsal
cartilages and the overlying muscular fibres. They are supplied with blood
from the palpebral branches of the ophthalmic artery, which run parallel
with and close to the borders of the lids. If the lids are everted, a number
of sebaceous glands (Meibomian) are to be seen arranged in longitudinal
parallel rows on the under surface of the tarsal cartilages. Their orifices
are situated behind the lashes, on the margins of the lids, and their
function is to prevent the lids from sticking together by their sebaceous:
secretion. Inflammation of one of these glands results in a small cystic
abscess, known as hordeolum or stye.

Within the orbit, just behind the external angular process, there is a
shallow depression for the lodgement of the lachrymal gland, which is
about the shape and size of an almond, and whose function is to secrete
the tears. It is fastened in its place by a few fibrous bands from the
periosteum attached to its upper surface, while below it rests loosely upon
the eyeball and its superior and external straight muscles. Sometimes
there is an accessory portion to the gland, which from its relation to the
upper lid is: called the palpebral portion (of Rosenmiiller). The gland
is invested by a capsule of connective tissue. In structure the gland
resembles very much the salivary glands, being an aggregation of lobes
and lobules held together by fibro-cellular tissue. There are about a
dozen excretory ducts, which take a parallel course and open in a row of
orifices two and one-half centimetres, or about an inch, above the edge
of the upper tarsal cartilage, upon the conjunctiva, the mucous lining of
the eyelids. The tears (lachryme) are the excessive secretion of the
PLATE 12,

of age.

15,

16.

17.

18.

19.

20,

21,

22.
23.
24,

. The superior longitudinal sinus of the dura mater.
. Section through the tables of the skull, showing the

diploic structure.

. The cut tissues of the scalp.

. The falx cerebri. ‘

. The inferior longitudinal sinus.

. The vene Galeni.

. The straight sinus.

. The fourth ventricle.

. Section of the cerebellum, showing the arbor vite.
. The torcular Herophili.

. The occipital sinus.

. The medulla oblongata.

. The spine of the first cervical vertebra.

. The spine of the second cervical vertebra.

Section through the ligamentum nuche and muscles
and fascia at the nape of the neck.

The spine of the third cervical vertebra.

The spine of the fourth cervical vertebra.

The spine of the fifth cervical vertebra.

The spine of the sixth cervical vertebra.

The spine of the seventh cervical vertebra (the verte-
bra prominens).

The convolution of the corpus callosum and anterior
cerebral vessels.

Section of the corpus callosum (showing the genu).

The fornix.

The crista galli of the ethmoid bone.

 

25.
. The corpora quadrigemina.

. The sella turcica, and position of the pituitary body.

. The sphenoidal sinus.

. The nasal meatuses.

. The pons Varolii, resting on the basilar portion of the

SBRBN8

31.

Median antero-posterior vertical section through the head, face, and neck of a powerfully-built man, thirty years

The frontal sinus.

sphenoidal bone.
Breach through the septum of the nose, opening into
the middle meatus.

. The opening into the Eustachian tube.
. The junction of the soft and hard palates,
. The vault of the palate.

. The incisor teeth of the upper jaw.

. The velum palati (the uvula).

. The incisor teeth of the lower jaw.

. The tongue.

. The pharynx.

. The epiglottis.

. The genio-hyoid muscle.

. The mylo-hyoid muscle.

. The body of the hyoid bone.

. The notch in the thyroid cartilage.

. The ventricle of the larynx.

. The commencement of the cesophagus.
. The cricoid cartilage.

. The spinal cord,

. The second ring of the trachea.

. The sterno hyoid and thyroid muscles.

N. B.—This section was made shortly after death, and photographed immediately, so as to preserve the relations of
the structures accurately.
Plate/2 Von I

 

Copyright /890,by GeoreeMc Cuettan M.D.

Dissected, Photographed and Colored from Nature by Georce Mc. Cueran, M 2

A rmstrong & Co. Lith. Boston.
THE ORBITAL REGION AND THE EYE. 85

lachrymal glands, which, under the influence of the emotions, or from
the irritation caused by cold, or by any foreign substance coming in
contact with the eye, overflow upon the cheek. Ordinarily the secretion
of the gland serves to keep the surface of the cornea constantly moist,
and to bathe the conjunctiva so that the movements of the lids and
of the eyeball shall be free.

The conjunctiva is reflected from the lids over the front of the eye,
and the two portions are known respectively as the palpebral and the
ocular. The palpebral portion is the thicker, is very vascular, and is pro-
vided with numerous fine papille, inflammation of which occasions the
disease called “granular lids.” At the inner canthus of the eye the
conjunctiva is reduplicated, forming the plica semilunaris, and its angle
of reflection from the lids to the eyeball is called the fornix conjunctive.
The continuations of the plica are the superior and inferior palpebral folds.
When the lids are closed, even in the momentary action of winking, the
conjunctiva becomes, as it were, a closed cavity which collects the tears
and conveys them to the inner canthus, where there is an oval space
between the two lids, the lacus lachrymalis. This space is occupied by the
caruncula lachrymalis, a small, reddish-colored, conical body consisting of
a number of follicles and resembling in structure the Meibomian glands.
The caruncula secretes the whitish matter frequently noticeable at the
inner angle of the eye.

Near the inner canthus there are on the margin of each lid slight
elevations, the papilla, with openings, the puncta, on their summits.
The puncta are the orifices of the canaliculi, which pass inward toward
the lachrymal sac. The manner in which these orifices are disposed for
the reception of the tears is influenced by the action of a slip of muscular
fibres from the orbicular muscle. This slip is called the ¢ensor tarsi (or
Horner’s muscle), in consequence of its arising from the ridge of the
lachrymal bone and being inserted into the tarsal cartilages of both lids
near their puncta. This little muscle may also act as a compressor of
the lachrymal sac. The canaliculi vary in their course,—a fact which
should be thoroughly understood in undertaking to relieve obstruction of
either of them by the introduction of probes or the knife. The superior
86 THE ORBITAL REGION AND THE EYE.

canal first extends upward, and then, bending at an acute angle, passes
inward and downward to join the inferior canal at its entrance into the
tear-sac. The course of the inferior canal (which is the one most often
affected) is first downward, and then it abruptly passes horizontally inward.
These canals are dense and elastic, somewhat dilated at their angles, and
have, especially the lower one, some spiral fibres from the tensor tarsi
muscle wound round their walls. The lachrymal sac occupies the lachry-
mal fossa within the nasal border of the orbit, with the tendo oculi and
the tensor tarsi muscle in relation to it anteriorly. Sometimes in dis-
tention of the lachrymal sac the tensor projects under the tendo oculi,
which occasions a bulging without and within, the tense ligament
depressing the top of the sac. . The tendo oculi is always the guide to the
sac. There are minute valvular folds in the mucous lining of the sac at
the entrance of the canals, which is continuous with the conjunctiva
through the canaliculi, and with the pituitary membrane of the nose
through the nasal duct, the lower constricted portion of the lachrymal sac.

The ocular portion of the conjunctwa is very differently arranged in
its relations to the sclerotic coat and to the cornea. The sclerotic conjunc-
tiva is very loosely attached to the subjacent coat, so as not to interfere with
the movements of the eyeball. It is very thin, transparent, and, except
when inflamed, nearly colorless. A few scattered blood-vessels extending
toward the cornea are generally visible in the healthy condition of the
organ; but under the stimulus of a foreign body or of some action upon
the vaso-dilator sympathetic nerves, very rapid congestion occurs, through
a peculiarly intricate capillary plexus of vessels which is derived from
the palpebral and lachrymal arteries.

The laxity of the sclerotic conjunctiva is demonstrated in chemosis,
where, owing to the distention, the patient cannot close his eye. The con-
junctival vessels are so feebly supported in this loose tissue that they often
rupture in paroxysms of whooping-cough or severe vomiting. Conjunctival
extravasations are unlike similar conditions elsewhere, and the blood retains
its scarlet arterial color, owing to the ready absorption of oxygen from the
atmosphere by the blood through the delicate conjunctival membrane.
In severe inflammations resulting from burns the mucous lining of the lids
THE ORBITAL REGION AND THE EYE. 87

is very often so contracted that the condition of entropion is induced. The
corneal conjunctiva is practically the outer layer of the cornea itself, con-
sisting chiefly of epithelium, and being extremely thin, non-vascular, and
transparent. There are numerous lymphatic vessels interspersed through
the capillary net-work of the conjunctiva, and the membrane is everywhere
extremely sensitive, owing to its abundant supply from the ciliary
nerves.

The cornea (pellucida) is the beautiful transparent convex struc-
ture projecting from the outer coat of the eyeball, of which it constitutes
about one-sixth part. It serves as a circular window by which the light is
admitted into the eye. The cornea is composed of four layers of various.
forms of tissue. The outer layer is the delicate adherent covering of the
conjunctiva, already described, which consists of several strata of epithelial
cells. Beneath this is the proper substance of the cornea, which is fibrous,
tough, and perfectly transparent, and upon which the thickness and strength
of the cornea depend. The thickness is very deceptive, so that in oper-
ating upon the cornea the knife may be thrust among the fibrous lamine
of which it is composed. These lamine are demonstrable only by the
use of reagents. There are some sixty lamine, the independent fibres of
each being arranged in a parallel direction, while those of the alternate
lamine cross at right angles the fibres of the lamine above and below.
In the recent state there is no trace of this complex condition of struc-
ture. Interposed between the lamelle are irregular spaces in which are
retained the so-called corneal corpuscles, which, upon careful inspection
under the microscope, appear to intercommunicate. ‘The proper sub-
stance of the cornea is continuous with the sclerotic coat, but, owing to
the modified character of its connective tissue, in which the elements are
so nearly alike in refractive power, in the healthy state it appears
homogeneous. Immediately beneath the conjunctival epithelium there is
a peculiar lamella, which has been named the anterior limiting or elastic
lamina (of Bowman), in contradistinction to the postercor elastic lamina (of
Descemet), which is the posterior modified lamella of the proper substance.

The posterior elastic lamina is remarkable for its tendency to curl upon
itself, with the corneal surface innermost, when it is separated from the rest
88 THE ORBITAL REGION AND THE EYE.

of the cornea. It probably has to do with maintaining the proper curva-
ture of the cornea. The degree of curvature varies in different eyes and
at different ages, being more prominent in early life, the cornea gradually
flattening with age. The posterior surface of the posterior elastic lamina is
covered with a continuation of the epithelial lining of the'aqueous chamber,
which resembles that of other serous membranes. There are no blood-
vessels normally within the structure of the cornea. At its circumference
the capillaries of the conjunctiva and sclerotic coat terminate in loops.
In keratitis these marginal arteries furnish branches which penetrate into
the interlamellated spaces. In the affection called pannus the conjunctival
arteries send out radiating branches which pass over the cornea through
the medium of the somewhat loosened epithelial covering and make it
appear to be vascularized, whereas the vessels are entirely superficial and
outside of the cornea proper. At birth the cornea is slightly opaque,
but shortly afterward becomes transparent. In old age it diminishes in
lustre and translucency, especially at the upper: and lower borders, where,
owing to fatty degeneration at these points, white crescents, forming the
arcus senilis, appear. It is remarkable that wounds of the cornea heal
promptly, in spite of the lack of direct blood-supply. There are very
numerous branches from the ciliary nerves which enter the laminated
tissue and form minute nerve-plexuses, rendering the cornea ordinarily
extremely sensitive. In glaucoma it loses its sensibility, owing to the
intra-ocular pressure upon the ciliary nerves before their branches reach
the corneal destination. The cornea is set into the anterior border of
the sclerotic coat very much as a watch-glass is received into its case,
its margin being bevelled on the outside and that of the sclerotic on
the inside.

The sclerotic coat is the white, tough, protecting coat of the eye,
which maintains the form of the globe, of which it constitutes the outer
covering for the posterior five-sixths. It is thickest behind, and thinnest
six millimetres, or about a quarter of an inch, from the cornea, where it is
apt to be ruptured through violence. This is partly due to the resistance
afforded by the recti muscles, which in a measure surround the globe
end are inserted into the sclerotic six millimetres, or a quarter of an
THE ORBITAL REGION AND THE EYE. 89

inch, from the cornea, leaving the intervening portions of the sclerotic
unprotected except by the loose conjunctiva, which gives the brilliant
white appearance to the front of the eyeball. The tendons of the
recti muscles are exposed by removing the ocular conjunctiva, when
they will be seen inserted upon the sclerotic coat in an elliptical manner,
so that their central portions approach the cornea more nearly than their
sides. This accounts for the unequal division of the tendons in the
operation for strabismus unless the whole tendon be hooked forward and
completely severed. In the case of the wmternal rectus muscle, which
most frequently requires division, this should be especially remembered,
as its tendon is nearer to the cornea than that of the others. The origins
of the inferior and internal recti occur at the inner and lower margins of
the optic foramen, in the apex of the orbit, from a fibrous band,—the
ligament of Zinn. The external rectus muscle has two heads, the upper
one arising from the margin of the optic foramen and the lower one from
the ligament of Zinn and the lower border of the sphenoidal fissure.
Between these two heads the motor oculi nerve, the nasal nerve, and the
abducent nerve pass forward to their distribution, together with the oph-
thalmic vein. The superior rectus muscle arises from the upper margin
of the optic foramen and from the dural sheath of the optic nerve.
The four recti muscles diverge from their origins and embrace the globe
of the eye, being invested with a loose fascia, the capsule of Tenon
(Plate 5, Fig. 2, No. 6). This fascia consists of two layers with an
intermediate space, and thus resembles the tunica vaginalis. There is
always a cushion of fatty tissue in the back of the orbit, even when
the general state of the individual is one of extreme emaciation, and
this cushion takes the shape of a cone, owing to its disposition about
the globe of the eye. The prominence of the eyes depends somewhat
upon the amount of this fat, and the “hollow-eyed” appearance in old
age and in wasting disease is consequent upon its partial absorption.
The recti muscles rest upon this orbital fat, and receive sheaths from the
ocular layer of the capsule of enon, which is closely united with the
margins of their tendons. The ocular layer of this fascia extends forward

to the anterior borders of the orbit, blending with the periosteum, and
12
PLATE 18.
Figure 1.

The relations of the great vessels and nerves at the base of the skull to the posterior wall of the pharynx.

1. The left lesser wing of the sphenoid bone. 10, The left common carotid artery, at its bifurcation.
2. The basilar portion of the sphenoid bone. 11, The right ear.
3. The left ear. 12. The right internal jugular vein.
4, The left mastoid cells. 18. The right parotid gland.
5, The left internal jugular vein. 14, The right spinal accessory nerve.
6. The left parotid gland. 15, The right pneumogastric nerve.
7. The left pneumogastric nerve. 16. The right glosso-pharyngeal nerve.
8. The left spinal accessory nerve. 17, The right internal carotid artery.
9. The left sterno-mastoid muscle. 18, The posterior wall of the pharynx.
Figure 2.
The face laid open on the left side to show the relations of the salivary glands and the vessels and nerves to the
tongue.
1. The lingual branch of the trifacial nerve, or the gus- | 13. Section through the ramus of the lower jaw.
tatory (?) nerve. 14, The uvula.
2. The tongue. 15. The tonsil gland.
3. The palato-glossus muscle. 16. The glosso-pharyngeal nerve.
4, The sublingual gland. 17, The pneumogastric nerve, brought forward.
$. The lingual artery. 18. The internal carotid artery.
6. The submaxillary gland. 19, The hypoglossal nerve.
7. The genio-hyoglossus muscle. 20. The stylo-pharyngeus muscle.
8. Section through the symphysis of the lower jaw. 21. The internal jugular vein.
9. The genio-hyoid muscle. 22. The external carotid artery.
10. The mylo-hyoid muscle. 28. The hyoid bone.
11. The parotid gland. 24. The descending thyroid artery.
12. The duct of Stenson. 25, The superior laryngeal nerve.
Figure 3.
The posterior wall of the pharynx opened to show the larynx and the relations of the palate and tonsils from behind.
1, The left internal jugular vein. 11, The right parotid gland.
2. The left parotid gland. 12, The right internal carotid artery.
3. The left palato-pharyngeus muscle. 18. The uvula.
4. The left spinal accessory nerve. 14. The right palato-pharyngeus muscle.
5. The left tonsil gland. 15. The dorsum of the tongue.
6. The left internal carotid artery. 16. The right tonsil gland.
7. The left pneumogastric nerve. 17. The right spinal accessory nerve.
8. The left portion of the pharyngeal wall, reflected. 18. The epiglottis.
9. The posterior wall of the larynx. 19. The right portion of the pharyngeal wall, reflected.
10. The right internal jugular vein. 20, The right arytenoid cartilage of the larynx.
Figure 4.

The lower jaw removed to show the palate, the tonsils, the fauces, and the tongue extended.

1. The roof of the mouth, formed by the hard palate.
2. The right palatine artery.

8. Section of the right ramus of the lower jaw.

4, The right parotid gland.

5. The right palato-glossus muscle.

6. The right palato-pharyngeus muscle.

7. The right tonsil gland.

8. The foramen cecum.

9. The circumvallate papille,

10.
11.
12.
13,
14.
15.
16.
17.

The fungiform papille.

The left palatine glands. ‘
The left palatine artery and nerve.

Section of the left ramus of the lower jaw.

The left parotid gland. t

The uvula.

The left tonsil gland.

The epiglottis.
Plate !3

 

Copyright/89/.by GeorseMc CrettanMD.
Armstrong & Co Lith Boston

Dissected, Photographed ang LO iored From Nature by GEORGE Me. Creccan, M 2.
THE ORBITAL REGION AND THE EYE. 91

especially with the two palpebral ligaments (formerly described). Owing
to this intimate relation of the tendons of the recti muscles to their sheaths
and the continuation of the latter with the anterior attachments of the
capsule, the functional insertion of these muscles is greatly increased.
This feature is particularly noticeable in the operation for strabismus,
when the fascial connection with the tendon must be completely cut
through as well as the tendon itself, or there will still be some counter-
acting hold upon the globe. In this relation Tenon’s capsule is of im-
portance, but much undue stress has been given to it. For the rest, the
outer orbital layer of the capsule, after sending areolar processes into the
interstitial tissue of the fatty cushion, passes backward with the posterior
part of the ocular layer to the back of the eyeball, blending with the
sheath of the optic nerve. In this locality there is a delicate areolar layer
which limits the so-called perineural space and allows the ciliary nerves
and vessels to pass forward to where they perforate the back part of the
sclerotic coat. The superior oblique muscle, or trochlearis, is a slender
muscular ribbon which arises by a tendinous slip in front of and at the
inner side of the optic foramen. It passes forward along the roof of the
orbit internally to the levator palpebree muscle, and ends in a rounded
tendon, which passes through a fibro-cartilaginous ring, the ¢rochlea, which
occupies a little fossa within the supra-orbital margin of the frontal bone
above the internal angular process. The tendon is provided with a syno-
vial sheath as it passes through the trochlea, whence it is directed beneath
the superior rectus muscle and is inserted into the sclerotic coat just without
that muscle, midway between the cornea and the entrance of the optic
nerve into the eye. The inferior oblique muscle is situated in the floor of
the orbit, and arises from the orbital plate of the superior maxilla near the
lachrymal fossa. It is directed beneath the inferior rectus muscle, to be
inserted by a thin tendon at the outer part of the sclerotic coat posterior to
the insertion of the superior oblique. The motor oculi nerve supplies the
inferior oblique and all the recti muscles, except the external rectus, which
receives the abducent nerve. The superior oblique receives the trochlear
nerve. The motor oculi nerve within the sphenoidal fissure divides into
two branches, which pass forward between the two origins of the external
92 THE ORBITAL REGION AND THE EYE.

rectus muscle, separated from each other by the nasal nerve. The upper
branch, which is the smaller, passes over the optic nerve and supplies the
superior rectus and levator palpebree muscles on their ocular borders. The
lower branch subdivides into three little nerves, one directed under the
optic nerve to supply the internal rectus, and another to the inferior rectus,
while the third runs along the floor of the orbit to the inferior oblique
muscle. The latter nerve furnishes a small branch to the ciliary ganglion.
Paralysis of ‘the motor oculi results in a drooping of the upper lid (ptosis),
a fixed condition of the eye, with divergent (external) squint from un-
opposed action of the external rectus muscle, and dilatation and immobility
of the pupil. If the paralysis is complete there is apt to be a slight pro-
trusion of the globe in consequence of the relaxation of the recti muscles.
The abducent nerve also passes forward between the two origins of the
external rectus muscle, above the ophthalmic vein, and terminates in
fine filaments on the ocular border of the external rectus. This nerve
carries with it from the cranial cavity some sympathetic fibres from the
carotid plexus, and within the orbit it receives other sympathetic fibres
from Meckel’s ganglion, sometimes a twig from the ophthalmic nerve.
Paralysis of the abducent nerve results in convergent (internal) strabismus.
The ¢rochlearis nerve (Plate 5, Fig. 2, No. 2) enters the orbit above the
other nerves and crosses the origin of the levator palpebrarum to be dis-
tributed to the superior oblique muscle, which it enters upon its orbital
surface, sending a recurrent branch to the dura mater at the base of the
cranium. Paralysis of the trochlearis nerve is attended with but little
change in the condition of the eye as regards mobility, as the loss of
function of the superior oblique muscle may be compensated for by the
vicarious action of the other muscles. In all cases of paralysis of the
orbital muscles there is more or less diplopia, or double vision. It will
be observed from the above that the motor nerves in the orbit enter the
muscles upon the ocular surfaces, except the trochlearis, which enters the
superior oblique muscle on its orbital surface.

The recti muscles move the eye upward, outward, downward, and
inward, according to their position. Acting together they tend to retract
the eye, the oblique muscles serving partially to antagonize them. The

»
THE ORBITAL REGION AND THE EYE. 93

superior and inferior recti muscles do not pursue a direct course, but rather
one obliquely outward to their insertions, and consequently their inde-
pendent action in elevating or depressing the eye would be accompanied
with some deviation and rotation inward. This is overcome by the peculiar
disposition of the oblique muscles, the inferior correcting the action of the
superior rectus and the superior correcting the action of the inferior
rectus. The independent action of the superior oblique muscle is to
rotate the eyeball downward and outward, that of the inferior oblique
muscle to rotate the eyeball upward and outward. The ingenious con-
trivance of these ocular muscles which brings a complete picture before
the eye in whatever position the head may be held can best be under-
stood by remembering the ré/e which the capsule of Tenon plays in
blending their tendinous insertions and thereby serving to modify and
harmonize their functions.

The sensory nerves of the orbit are branches of the ophthalmic division
of the trifacial nerve,—viz., the nasal, frontal, and lachrymal nerves. The
nasal nerve, after passing through the sphenoidal fissure between the two
origins of the external rectus muscle, separating the two branches of the
motor oculi nerve, as has been stated, crosses over the optic nerve, beneath
the levator palpebre and superior rectus muscles, to the inner wall of
the orbit, where, after giving off the infra-trochlear nerve, it leaves the
orbit by the anterior ethmoidal foramen. This nerve contributes the long
root to the ciliary ganglion in its passage between the origins of the rectus
muscle; also the long ciliary nerves, which, passing on the inner side of
the optic nerve, receive filaments from the ciliary ganglion and pierce the
sclerotic coat to go to the iris. The wnfra-trochlear nerve passes to the
inner angle of the orbit, to supply the lachrymal sac, the skin over the
inner corner of the eyelids, and the adjacent side of the nose. The
frontal nerve, the second branch of the ophthalmic nerve, runs along
the upper surface of the levator palpebre muscle, and about the middle
of the orbit divides into the supra-trochlear and supra-orbital nerves.
The supra-trochlear nerve passes above the pulley of the superior oblique
muscle to the inner angle of the orbit, where it forms a connecting loop
with the infra-trochlear branch of the nasal nerve, and sends a branch
94 THE ORBITAL REGION AND THE EYE.

between the orbicular muscle and the orbital arch to supply the skin of
the upper eyelid, forehead, and nose (Plate 53, Fig. 1, No. 18). Besides
these there are several filaments which penetrate the frontal bone and
supply the mucous lining of the frontal sinuses. The supra-orbital nerve is
really the continuation of the frontal nerve. It passes through the supra-
orbital notch or foramen and supplies sensation to the orbicular and
occipito-frontalis muscles and the skin of the upper eyelid, forehead,
and scalp. The lachrymal nerve passes on the outer side of the orbit,
above the external rectus muscle, accompanying the lachrymal artery to
supply the lachrymal gland. Before entering the gland it gives off a little
twig which communicates with the orbital branch of the superior maxillary
nerve. In front of the lachrymal gland the nerve pierces the palpebral
ligament and supplies the skin at the outer border of the upper eyelid.
Paralysis of the ophthalmic nerve is attended by loss of sensation in the
globe of the eye and the mucous lining and cutaneous surfaces supplied by
its branches, a condition which readily exposes the eye to injury.

The ophthalmic or ciliary (sympathetic) ganglion is a tiny, reddish-
colored, square-shaped body embedded in the orbital fat between the
external rectus muscle and the optic nerve in the back of the orbit. It
is in close relation to the ophthalmic artery. This ganglion has a motor
root from the branch of the motor oculi nerve to the inferior oblique
muscle, a sensory root from the nasal nerve, and a sympathetic root
from the carotid plexus which joins it with the sensory root. From
the anterior border of the ciliary ganglion about a dozen short, delicate,
ciliary nerves pass forward with the ciliary arteries, in a wavy course,
close to the optic nerve, and pass through the back of the sclerotic
coat, where they are joined by the dong ciliary branches from the nasal
nerve and are distributed to the ciliary muscle and the iris.

The ophthalmic artery, after its origin from the internal carotid artery
near the anterior clinoid process of the sphenoid bone, enters the orbit
with the optic nerve through the optic foramen. It first holds a position
external to the artery, but within the orbit becomes very tortuous, crossing
over the optic nerve to the inner side of the orbit, and giving off numerous
branches. The first branch of importance is the arteria centralis retina,
THE ORBITAL REGION AND THE EYE. 95

which enters obliquely the outer side of the optic nerve close to the optic
foramen and passes forward in the centre of the nerve to the retina. From
the ophthalmic, near the above, are given off the internal and external
cihary branches, the former subdividing in the perineural space into six
or seven minute branches, and the latter into as many more, all of which
pierce the sclerotic coat. There is a long branch of each of these sets,
which pass one upon each side of the optic nerve, and, after entering the
sclerotic coat, continue between it and the choroid coat toward the iris.
On the outer side of the optic nerve, and between the external and superior
recti muscles, the lachrymal artery arises. It proceeds with the lachrymal
nerve to the lachrymal gland, being finally distributed to the neigh-
boring portion of the conjunctiva and eyelids. It also sends a recurrent
branch through the sphenoidal fissure, which anastomoses with a branch
from the middle meningeal artery. Anterior to the lachrymal artery,
the muscular branches are distributed to the ocular muscles. The-supra-
orbital artery is a very small -vessel which accompanies the supra-orbital
nerve in its course and distribution. The anterior and posterior ethmoidal
arteries pass out of the orbit through the ethmoidal foramina, the anterior
being accompanied by the nasal nerve. The palpebral arteries supply the
lids and form arches around their margins by anastomosing with the lach-
rymal and infra-orbital arteries. The nasal and frontal arteries are the
terminal branches of the ophthalmic. The nasal artery leaves the orbit
above the tendo oculi and joins the angular branch of the facial on the
nasal side of the eye. The frontal artery inosculates with the supra-
orbital artery at the inner angle of the eye. There are two ophthalmic
veins, which convey the venous blood from the orbit to the cavernous
plexus around the internal carotid artery. The superior ophthalmic vein
commences at the inner angle of the eye, where it communicates with the
frontal and angular veins. Thence it passes along the inner and upper
part of the orbit, receiving tributary veins which correspond to the arteries
with which they are in relation. The inferior ophthalmic vein receives the
blood from the outer and lower part of the orbit and passes along the floor
to empty into the superior vein, or directly into the cavernous plexus.
The optic nerve, from the optic foramen to its entrance at the back
96 THE ORBITAL REGION AND THE EYE.

of the globe of the eye on the nasal side of its axis, is about two and one-
half centimetres, or an inch, in length. It is enveloped by a double sheath,
consisting of a prolongation of the pia mater within and of the dura
mater without. The dural sheath is firm and fibrous, and is continuous
with the sclerotic coat, and at the optic foramen it also blends with the
periosteum of the orbit from which the ocular muscles arise. The optic
nerve is surrounded by the perineural space, formed by the inflection of
the orbital fascia, already mentioned, in which the ciliary vessels and
nerves pass forward. The orbital fat separates it from the recti muscles.
It is pierced on its outer side, near the optic foramen, by the central, or
retinal, artery, which, with its vein, passes forward in a central canal made
up of processes from the pial sheath.

The eyeball is composed of three concentric coats,—an outer fibrous,
strong, and protective coat, consisting of the sclerotic and cornea; a middle
or vascular coat, composed of blood-vessels, muscular tissue, and dark pig-
ment cells, and consisting of the choroid, the iris, and the ciliary processes ;
and an inner or nervous coat, the retina, which is the expansion of the
optic nerve. Within these there are three transparent media for the trans-
mission of light,—viz., the aqueous humor in front, the crystalline lens in
the middle, and the vitreous body behind. The optic nerve becomes
slightly constricted as it approaches the sclerotic coat, and breaks up
into a number of bundles of fibres, which pass through minute apertures
in the sclerotic coat, giving a cribriform character to this portion of
the membrane, which is therefore called the lamina cribrosa. The porus
opticus is the central and largest of these apertures, and transmits the
retinal vessels. Around the cribriform lamella there are many puncta

for the transmission of the ciliary vessels and nerves. The anterior
ciliary arteries, which are derived from the muscular arteries of the orbit,
run along the tendons of the recti muscles, pierce the sclerotic coat very
near the cornea, and form the circular anastomosis of the iris. There is
a small oval canal running round the corneal attachment of the sclerotic,
the sinus circularis iridis, or canal of Schlemm (or Fontana). At the junc-
tion of the posterior elastic lamina of the cornea, or Descemet’s membrane,
already described, with the sclerotic coat on its inner surface, it spreads out
THE ORBITAL REGION AND THE EYE. 97

into a circle of radiating processes,—the ligamentum pectinatum wridis,—
some of which are attached to the front of the iris at its circumference
and others to the anterior part of the sclerotic and choroid coats. The
intervals between these processes are called the spaces of Fontana, and
these communicate with the canal of Schlemm, conveying the fluid of the
anterior chamber into it.

The choroid coat is the soft vascular tunic which underlies the
sclerotic coat, and the space between the two is traversed by a mesh-work
of connective-tissue fibres containing stellate pigment cells, the supra-
choroid membrane. The connective tissue which underlies the sclerotic
coat and unites it with the choroid is called the lamina fusca, and the
contiguous surfaces of these two layers of tissue are lined with epithelium,
having a lymph-space between them which is in reality continuous with
that of the capsule of Tenon, through the prolongation of that fascia
accompanying the ciliary vessels and nerves. Into this lymph-space
hemorrhage may occur in injuries to the globe of the eye, and the same
occurrence sometimes follows the operation of iridectomy or of extraction of
cataract, owing to the sudden diminution of ocular tension. The choroid
coat is deficient posteriorly where the optic nerve enters, but from this
point to the iris anteriorly it consists of two layers,—the owter one con-
taining principally large plexuses of veins, the ven vorticose, and the
inner one being composed of a net-work of capillaries from the long and
short ciliary arteries, the tunica Ruyschiana. The veins of the outer coat
of the choroid present remarkable regularity in their arrangement, and con-
verge to five or six equidistant trunks, which, after piercing the sclerotic
coat at the outer side of the lamina cribrosa, terminate in the ophthalmic
veins. Between the veins run forward the choroid arteries, consisting of
the anterior ciliary arteries, which come from the muscular arteries of the
orbit entering anteriorly, and the long and short posterior ciliary arteries,
entering around the optic nerve. Interspersed between the vessels are
dark pigment cells which communicate with one another by fibrous pro-
longations and constitute a delicate net-work. The inner layer of the
choroid, which is formed by the radiating capillaries from the choroid

arteries, is the most delicate vascular net-work found in any tissue. On the
13
PLATE

14,

Figure 1.

Transverse section of the neck of a negro (male), aged thirty years.

cricoid cartilage in front.

On nore own

worntanrpnony

. The cut cords of the right brachial plexus of nerves.
. Section through the apex of the right lung.

. The right innominate vein.

. The right vagus nerve.

The innominate artery.

. The sternal end of the sterno-mastoid muscle.
. The trachea.

. The sterno-thyroid and sterno-hyoid muscles.
. The recurrent laryngeal nerve.

. The esophagus.

. The left common carotid artery.

. The left vagus nerve.

. The left innominate vein.

From the fifth cervical vertebra behind to the

. The spinous process of the fifth cervical vertebra. 14. The right complexus muscle.

. The left transverse process of the fifth cervical vertebra. | 15. The medulla spinalis.

. The left vertebral artery and vein. 16. The right transverse process of the fifth cervical ver-

. The body of the fifth cervical vertebra. tebra.

. The left vagus nerve (or pneumogastric nerve). 17. The right vertebral artery and vein.

. The left common carotid artery. 18. The longus colli muscle.

. The esophagus. 19. The right vagus nerve (or pneumogastric nerve).

. The left internal jugular vein. 20. The right common carotid artery.

. The left lobe of the thyroid body. 21. The right internal jugular vein.

. The rima glottidis, seen through the cricoid cartilage. 22, The right lobe of the thyroid body.

. The left external jugular vein. 23. The right omo-hyoid muscle.

. The hoop of the cricoid cartilage in front. 24, The right external jugular vein.

. The right trapezius muscle. 25. The sterno-thyroid and sterno-hyoid muscles.
Figure 2.

«

Transverse section at the root of the neck (same as Figure 1) from the first dorsal vertebra to the top of the sternum.

14. The left subclavian artery.

15. The left scalenus anticus muscle.

16. The supra-scapular artery and vein.

17. The right scalenus anticus muscle.

18. The right transverse process of the first dorsal vertebra.
19. The head of the right first rib.

20.
21,
22.
23.
24.
25.
26.

The medulla spinalis.

. The spine of the first dorsal vertebra.

. Section through the intervertebral disk.

. The left transverse process of the first dorsal vertebra.
. The apex of the left lung.

. The splenius muscle.

. The trapezius muscle.

N. B.—These sections were made on a recent well-developed cadaver, placed in the horizontal position, without any
freezing or hardening agent, and the plates represent the relations of the parts absolutely as they were.
Plate |4 Von I

 

 

 

Copynght/89/ by GeoreeMcCiewanMD
Dissected, Photographed aid Colored from Nature by Georce Mc. Clean, MD. Armstrang & Ca. Lith Boston,
THE ORBITAL REGION AND THE EYE. 99

inner surface of this vascular tissue is a very thin membrane, the lamina
vitrea, which separates it from the pigmentary layer of the retina. The
choroid coat splits anteriorly into the ciliary muscle in front and the ciliary
processes behind, both constituting the ciliary body. The ciliary processes
consist of about seventy large and small, alternating, plaited folds of the
tissues of the choroid, with their vessels, nerves, and pigment. They are
arranged radially behind the ciliary muscle and the iris, and posteriorly
fit into corresponding folds of the suspensory ligament of the lens, espe-
cially into the part called the zone of Zinn, and their rounded free ends,
which are devoid of pigment, project a little distance into the posterior
chamber, and rest upon the capsule of the lens.

The ciliary muscle is a zone of unstriped muscular fibres at the front
of the choroid coat, arising close to the canal of Schlemm, at the junction
of the sclerotic coat and the cornea. Some of the fibres radiate backward
and blend with the ciliary processes, and others form the circular ciliary
muscle (or ciliary ligament) around the periphery of the iris. Its action
is to accommodate the eye to objects at various distances, which it prob-
ably accomplishes by drawing on the ciliary processes and thus relaxing
the suspensory ligament of the lens, rendering the anterior surface of the
lens more convex. The nerves supplying the ciliary muscle are derived
from the long and short ciliary nerves. The ciliary region is the danger-
ous area of the eye, owing to its important vascular and nerve anastomoses
and its relations to the cornea, iris, choroid coat, retina, and vitreous body.
Wounds of the cornea in front of this region, or of the sclerotic coat behind
it, are not so hazardous, but any traumatic affection of the ciliary body is
liable to be followed by the gravest results. Not only are the contiguous
parts readily involved by the spread of inflammation from this locality,
but experience has shown that that terrible affliction called sympathetic
ophthalmia—whatever may be the insidious and latent process by which
it travels from one eye to the other—invariably has its origin in some
injury to the ciliary region.

The iris (a rainbow), so called from its various colors in different
individuals, is the continuation of the ciliary muscle. It is a circular
contractile membrane, with a round hole a little to the inner side of its
100. THE ORBITAL REGION AND THE EYE.

centre, the pupil, and hangs like a curtain in the aqueous humor behind
the cornea and in front of the ciliary processes and the lens. The iris
divides the space oceupied by the aqueous humor into the anterior and
posterior chambers, which communicate through the pupil. It is connected
with the choroid coat at its circumference through the ciliary muscle, and
by the ligamentum pectinatum (already described) with the cornea. Its
connection, however, with these parts is not very close, for the iris is
sometimes torn from its attachments in contusions, without serious injury
to the adjacent structures. Its yielding nature is taken advantage of in
the operation of iridectomy, when the piece of the iris to be excised is
readily drawn through the corneal incision. At the pupillary border it
rests lightly upon the lens, and consequently when inflamed, as in iritis, it
may become attached to the latter. The .coloring-matter of the iris is due
to minute pigment cells upon its surfaces, the posterior radially-furrowed
surface being called the wvea, from its ordinary grape-like color. The color
of different eyes depends upon the disposition of the pigment cells in their
irides. In blue or light-colored eyes the pigment is upon the uvea, or
posterior surface, and is modified by being seen through the texture of the
iris, whereas in dark eyes the pigment is upon both surfaces. The iris
consists of connective tissue and unstriped muscular fibres, and serves as a
diaphragm to the eye, by which the amount of light passing through the
pupil to reach the retina is regulated.

The fibres of the connective tissue are arranged longitudinally and cir-
cularly, the former radiating toward the pupil, having between them the
vessels and nerves, and the latter surrounding its attached border. The
pigment cells are intermingled in the meshes of the connective tissue.
The muscular fibres are also longitudinal and circular. The longitudinal
muscular fibres, constituting the dilatator pupille, form a very thin layer
of radiating fibres, which converge from the circumference toward the
pupil, where they are inserted into the sphincter pupille, which consists
of well-marked circular muscle-fibres on the posterior surface of the
margin of the pupil. Only the latter are clearly demonstrable in the
human eye. The size of the pupil varies, according as the muscular
fibres are contracted or relaxed, from one and one-fourth to eight and
THE ORBITAL REGION AND THE EYE. 101

one-half millimetres, or from one-twentieth to one-third of an inch.
During the first seven months of foetal life the pupil is closed by a trans-
parent vascular membrane, the membrana pupillaris, which until that
period completely separates the anterior and posterior chambers from each
other. About the eighth month this membrane is gradually absorbed, there
being very little trace of it left normally at birth. The iris is supplied by
the two long ciliary arteries and the anterior ciliary arteries. The long
ciliary arteries (described in connection with the choroid coat) near the
attached border of the iris divide into upper and lower branches, which
anastomose with each other and the anterior ciliary arteries, forming the
eirculus major of the ciliary muscle, from which two sets of small branches
are given off, one to supply the muscle, and the other converging toward
the pupil and forming the cvrculus minor of the iris. The latter gives off
numerous capillaries which terminate in veins, and they in turn empty into
the canal of Schlemm. The nerves of the iris are non-medullated fibrils
continued from the nerves in the ciliary muscle, where they form a
plexus. Originally they are derived from the long ciliary nerves, from
the nasal branch of the ophthalmic nerve, and from the dozen or more
branches from the ciliary ganglion, which, as already described, has a motor
root from the motor oculi nerve, a sensory root from the nasal nerve,
and a sympathetic root from the carotid plexus. Although the nervous
distribution to the iris is of a very complex character, owing to this
diversity of origin of the fibres composing the ciliary nerves, it is
believed that the circular fibres (sphincter) of the iris are chiefly supplied
by the motor fibres from the motor oculi nerve, while the radiating
fibres (dilatator) are supplied merely by the sympathetic filaments,
possibly inhibitory. The motor fibres and sympathetic fibres appear
to exercise an antagonistic influence upon the pupil, as experiment has
shown that division of the motor oculi nerve is followed by dilatation
and that of the sympathetic by contraction of the pupil. The sensibility
of the iris, as well as of the cornea, is due to the filaments derived
from the nasal nerve. The accommodation of the eye for vision at long
or short distances, with the object exposed in a bright or a dim light,
requires a degree of perfectness in the regulating apparatus to which
102 THE ORBITAL REGION AND THE EYE.

the iris greatly contributes. It has been stated (page 100) that the circular
fibres are the most marked in the human iris; and the many changes
to which they are subjected are probably due to the influence of the
vaso-motor sympathetic ciliary nerves on the capillary vessels of the
iris, for not only does the influence of the light upon the retina incite
by reflex action a corresponding degree of contraction or dilatation of
the pupil according to its intensity, the impression probably being trans-
mitted through the optic nerve to the optic lobes in the brain and
thence to the motor oculi nerve and its continuations, but there are
other conditions with which the light has nothing to do. The pupil is
always observed to be dilated in coma, from compression of the brain in
many states of shock, in many mental or nervous derangements, and in
the general relaxation of the muscular system at the moment of death.
One of the physiological actions of belladonna, which seems to paralyze
the vaso-motor nerves, is to dilate the pupil. Opium, on the contrary, by
increasing the tension of the capillaries, induces contraction of the pupil.

The aqueous humor consists of a few drops of clear limpid alkaline
fluid, which fills the space between the cornea and the lens in which the
iris is suspended, dividing the space, as already mentioned, into the anterior
and posterior chambers. The posterior chamber is a very small angular
interval between the back of the iris and the ciliary processes and the
suspensory ligament and the capsule of the lens. The anterior chamber is
in communication with the canal of Schlemm—the circular venous canal
at the junction of the cornea with the sclerotic coat—through the spaces
of Fontana. This canal therefore brings the anterior chamber into relation
with the venous circulation, and thus the ready absorptive power of the
aqueous humor may be explained,—as is proved in the speedy removal
of extravasated blood, or in the treatment of soft cataract by the “needle
operation.” The aqueous humor is also rapidly secreted after the extraction
of a cataract.

The crystalline lens is a perfectly translucent, biconvex, semi-solid
body placed immediately behind the pupil, and completely surrounded by
an equally translucent elastic capsule. The capsule of the lens resembles
the elastic lamina of the cornea, and is thicker in front than behind. The
THE ORBITAL REGION AND THE EYE. 103

anterior surface of the capsule is in contact with the free pupillary margin
of the iris. There is no vascular connection between the lens and its
capsule, but the capsule is separated from the front of the lens by a layer
of epithelium which after death exhales the so-called liquor Morgagni.
The capsule is retained in its position by the suspensory ligament of the lens,
or the zone of Zinn, which is the continuation of the hyaloid membrane,
extending from the vitreous body to the ciliary processes. The elasticity
of the capsule is manifest from the curling outward of its edges in
lacerated wounds, or in cataract operations. When the capsule is wounded
the aqueous humor is imbibed by the fibres of the lens to a greater or less
degree, with proportionate opacity.

The dens consists of three triangular segments, which are composed of
numerous concentric layers. It is somewhat soft and gelatinous externally,
but each successive layer becomes more dense toward the centre, which is
hard and is called the nucleus. The lamine consist of minute parallel
fibres which are hexagonal prisms fitting accurately into one another by
a dovetailing of their edges. The lens varies with age and the conditions
of myopia and presbyopia. In early life it is almost spherical, but in old
age it becomes flattened, yellowish, and less transparent. In the adult it is
distinctly more convex behind than in front. The function of the lens is
to bring the rays of light coming from any object to a focus upon the
retina. The canal of Petit is the so-called encircling space between the
capsule of the lens and its suspensory ligament, formed by a splitting of the
latter. It probably contains a semi-fluid extension of the vitreous humor ;
when inflated by a blow-pipe it presents a peculiar beaded appearance,
owing to the plaiting of the suspensory ligament on the front of the lens. °

The vitreous body is the transparent jelly-like substance filling the
cavity of the retina, immediately behind the lens, which it accommodates
in front in a depression (the Ayaloid fossa) adapted to its capsule. It is
surrounded, except in front, by the delicate, transparent hyaloid membrane,
which, as already explained, passes forward anteriorly to form the suspen-
sory ligament of the lens. The latter portion of the hyaloid membrane
contains longitudinal elastic fibres. The vitreous body consists of a fluid
contained in cellular meshes which freely intercommunicate, as is seen in
1.
2.
3.

15.
16,

17,

they form the laughing muscles of Santorin1.

PLATE

15.

Anterior view of the muscles of the face of a well-developed man, aged thirty-five years, showing the delicate inter-
lacing of the fibres about the corners of the eyelids and mouth. This dissection was made with especial care to demon-
strate the anatomy of expression in its application to the facial markings now considered characteristic of disorders
pertaining to mental, nervous, digestive, and respiratory functions.

The epicranial aponeurosis or (galea capitis).

The right frontal muscle.

The external lateral fibres of the right frontal muscle,
some of which are attached to the external angular
process of the orbit, and others blend with the adja-

- cent orbicularis muscle.

. The pyramidal slip from the frontal muscle descending

upon the nasal bone.

. The right temporal aponeurosis.

. The right orbicularis palpebrarum muscle.

. The right compressor naris muscle.

. The right levator labii superioris et ale nasi muscle.

. The right levator labii proprius muscle.

. The right levator anguli oris muscle.

. The depressor alz nasi muscle.

. The depressor septum nasi muscle.

. The right zygomatic muscle.

. The superior labial portion of the orbicularis oris

muscle.

The right masseter muscle.

The inferior labial portion of the orbicularis oris
muscle.

The triangular, or depressor anguli oris (labii inferioris)
muscle.

 

18,
19,

20.
21,
22.

23.
24,

25,
26.
27,
28.
29,
30.
31.
32.
33.
34,
35.
36.

The right levator menti muscle.

The quadratus, or depressor labii inferioris proprius
muscle.

The inter-frontal aponeurosis.

The peculiar looping of the fibres of the frontal muscle.

The transverse fibres of the orbicularis palpebrarum
muscle, which arise from the internal angular ,pro-
cess of the orbit, called the corrugator supercilit
muscle.

The left pyramidalis nasi slip from the frontal muscle.

The interlacing of the fibres of the frontal with the
orbicularis at the inner corner of the eyelid.

The tendo oculi.

The left compressor naris muscle.

The left orbicularis palpebrarum muscle.

The left levator labii superioris et alee nasi muscle.

The left levator labii superioris muscle.

The left levator anguli oris muscle.

The left zygomaticus muscle.

The left buccinator muscle (just seen in this view).

The left masseter muscle.

The left depressor anguli oris muscle.

The left depressor labii inferioris muscle.

The left levator menti muscle.

N. B.—The platysma muscles have been removed from their attachment at the outer corners of the mouth, where

The vessels and nerves have also been removed, as they are shown in

other plates, in order to give a clearer idea of the interdependence of the facial muscles,
Plate /5 Wea

 

Copyright (890,by GeorceMc li weLLAN, MLD.
Dissected, Photographed and Colored trom Nature ty Georce Mc. CieLLan, MD, e Aemerrene talent Beeent
THE ORBITAL REGION AND THE EYE. 105

puncture of the body, when the humor drains away. There is a central
canal (of Stilling) which passes from the position of the entrance of the
optic nerve to the middle of the back of the capsule of the lens: it is
lined by a prolongation of the hyaloid membrane, and contains fluid. In
the foetus this canal conveys the little hyaloid artery from the central
artery of the retina to the capsule of the lens. On the inner side of the
hyaloid membrane there are many granular corpuscles, which under the
microscope exhibit amceboid movements. The muscw volitantes which
often trouble short-sighted persons are due to opaque matters suspended
in the vitreous body, and closely resemble the hyaloid corpuscles.

The retina is the delicate nervous membrane formed by the expan-
sion of the optic nerve after its passage through the sclerotic and choroid
coats, upon which the images of external objects are received. It is the
so-called inner coat of the eye, and is placed between the choroid and the
hyaloid membrane, extending as far forward as the ciliary ligament, where
it terminates in a fine serrated border,—the ora serrata,—a single lamina
of its tissue, the pars ciliaris, being continued to the ciliary processes and
the iris. The retina is thickest at the entrance of the optic nerve, and
gradually becomes thinner toward the ora serrata. Its internal (hyaloid)
surface is smooth, and during life appears as a transparent pinkish tissue.
At the point of entrance of the optic nerve there is a round disk, called
the porus opticus, in the centre of which may be seen with the ophthalmo-
scope the central artery of the retina entering and branching above and
below, and the central veins converging and passing inward. There is
also a little prominence of the nerve-substance at this point, the optic
papille. This prominence is sometimes called the blind spot (or punctum
cecum), because it is altogether insensible to the rays of light. In the
recent state, at the fundus of the eye, directly opposite the pupil, in the
centre of the axis of vision, there is an oval, yellow spot (macula lutea)
in the retina, with a central conical pit, the fovea centralis. Here the
structure is so thin that the dark pigmentary layer of the retina (the
tapetum) is seen through it, and it is at this point that the impression of
light is greatest and vision is considered to be most perfect. |

The porus opticus is about two and one-half millimetres, or one-tenth
14
106 THE ORBITAL REGION AND THE EYE.

of an inch, to the inner side of the macula lutea. After death there is a
minute transverse fold in the retina extending from the centre of the fovea
to the papilla. The retina appears to the naked eye as a simple, soft, trans-
parent membrane, but when examined under the microscope it is found to
be an exceedingly complex structure, showing the most elaborate organi-
zation. It is composed of eight layers, all differing from one another,
arranged in strata, and supported by an extremely delicate connective-
tissue framework (the sustentacular tissue), which upon the choroid and
vitreous surfaces becomes somewhat condensed and appears membranous,
forming respectively the so-called membrana limitans externa and mem-
brana limitans interna. The first, outer, or pigmentary layer, the tapetum
nigrum of the retina, is a layer of hexagonal epithelial nucleated cells,
containing pigment granules only on their ener portions, which, although
in the closest relation with the choroid coat, are prolonged like fine
tapering filaments between the numberless elongated bodies of the second
layer. The pigment is probably so disposed to absorb the rays of
light, and thus, preventing its reflection, to convert it into some form of
nervous force. The second or columnar layer is composed chiefly of
minute, bacillus-like bodies, which penetrate externally into the pigmen-
tary layer and internally into the subjacent outer nuclear layer, being
supported by a trabecular arrangement of the connective tissue (the mem-
brana limitans externa). These bodies are also known as the rods and
cones, the former being club-shaped and greatly outnumbering the cones,
which are flask-shaped and isolated and scattered among the rods. The
rods are longer and therefore more in relation with the pigmentary layer,
while the cones are shorter; and they are both connected with the sub-
jacent outer nuclear layer by delicate fibrous prolongations. The rods
are not found in the yellow spot. Little is known regarding the function
of these interesting little bodies beyond the facts of comparative anatomy
that among those animals and birds which seek their food by night
the retina consists solely of rods, and that in the case of birds which
live on brightly-colored insects the cones are about as numerous as the
rods. From these facts the inference is drawn that the rods are concerned
in the discrimination of the quantity of light, the cones in that of its
THE REGION OF THE NOSE AND THE NASAL CAVITIES. 107

quality or color. The next succeeding four layers are alternating nuclear
and molecular layers, called owter and inner, from their relative positions.
They consist of strata of clear nucleated corpuscles or granules, modified
-in each layer so as to offer some peculiarities, and embedded in the
retinal connective tissue. They are severally connected by upward and
downward prolongations, the outer nuclear layer with the rods and cones
as above stated, whereas the inner molecular layer joins the seventh or
ganglionic layer. The last is a very clear stratum of spheroidal nerve-
cells connected by oblique processes with the eighth retinal layer, which
consists of the ultimate fibres of the optic nerve. The ganglionic cells
are inserted into several strata in the vicinity of the yellow spot, and
within it into six or seven. The layer of nerve-fibres is composed of the
axis cylinders only, and is continued as far forward as the ora serrata,
arranged for the most part in bundles which interchange so as to form
plexuses. At the yellow spot this layer is interrupted by the accumulation
of nerve-cells.

THE REGION OF THE NOSE AND THE NASAL
CAVITIES.

The special organ of the sense of smell consists of an external portion,
the nose, and internal portions, the nasal fosse, or nasal cavities.

The nose is the prominent feature which projects anteriorly between
the orbits from the upper part of the face, being connected by its summit
with the forehead and by its base with the upper lip. It serves as the
chief avenue of respiration when the mouth is closed. The skeleton of
the nose consists of the two nasal bones and the nasal processes of the
superior maxillary bones, to which is attached a cartilaginous framework
composed of five peculiarly-shaped movable cartilages.

The nasal bones are severally of an elongated quadrilateral shape, being
‘narrow and thick above, where they are firmly attached by suture with the
nasal spine of the frontal bone, constituting the nasion, and wide and thin
below, where they form the upper margin of the anterior nasal fosse of
the skull (Plate 28) and in the recent state give attachment to the upper
108 THE REGION OF THE NOSE AND THE NASAL CAVITIES.

lateral nasal cartilages. They are strongly united in the middle line,
forming “the bridge” of the nose, this juncture being strengthened by
their inner borders projecting as a longitudinal crest, which connects
them with the ethmoidal portion of the septum of the nose. Their outer
borders are bevelled, and supported by the contiguous borders of the
superior maxillary bones. The width and length of the nasal bones vary
greatly in different skulls, and, as they are almost immediately beneath
the skin (Plate 1), they give shape and character to the organ. The under
surfaces of the nasal bones are grooved for the nasal nerves, and perforated
by a few small foramina for the transmission of vessels.

The nasal processes of the superior maaillary bones are triangular, thick,
bony plates which extend upward on each side of the nose to be joined
by suture with the frontal bone. Their anterior borders are serrated for
articulation with the nasal bones,—the form and dimensions of the nose
being mainly dependent upon the development of these processes and the
manner in which the nasal bones are set upon them. The outer surfaces
of the nasal processes are serrated and concave; the internal surfaces
are rough, and present two well-marked ridges, the superior and inferior
turbinated crests, the former articulating with the middle turbinated portion
of the ethmoid bone and the latter with the inferior turbinated bones on
each side.

The cartilaginous framework of the external nose is formed of a median
septum and two lateral segments on both sides. The cartilage of the
septum is a smooth triangular plate inserted posteriorly into a groove
in the perpendicular plate of the ethmoid bone; anteriorly, where it is
thicker, it is connected above with the nasal bones and adjacent lateral
cartilage, and below with the vomer and the palatine processes of the
superior maxillary bones. The septal cartilage separates the anterior
portions of the nasal cavities, and up to the seventh year of age is usually
straight, but subsequently it is apt to incline to one side (usually the left),
according to the deviation of the vomer (Plate 28, No. 39). Sometimes
it is perforated, and thus establishes a communication between the cavities.
The dateral cartilages consist of an upper triangular piece and a lower
oval piece on each side, which together give shape to the wings and tip
THE REGION OF THE NOSE AND THE NASAL CAVITIES. 109

‘of the nose and support the integument. Each upper cartilage is attached
above to the margin of the nasal bone and adjoining nasal process, in
front to the septum, and below to the lower cartilage. The latter is.
curved upon itself so as to form the outer and inner boundaries of the
external orifice of the nostril. It approaches its fellow of the opposite
side internally, and thus forms the upper part of the colwmna nasi, the
partition between the nostrils. When the lower lateral cartilages are not
in contact there is a median furrow which is sometimes well marked at the
tip of the nose. These cartilages are connected to each other and to the
bones by a tough fibrous membrane, the perichondrium. In this tissue,
in relation to the superior maxille, there are usually several nodules,—
sesamoid cartilages. The elasticity of these cartilages preserves the size
and shape of the nostrils, and enables the muscles moving them to expand
or contract the orifices so important in respiration. The skin over the
root of the nose: below the forehead, on the sides and the greater part of
the dorsum, is thin and loose; but over the wings (a/@) and on the point -
it is thick and very adherent to the parts beneath, and remarkable for
the number and size of its sebaceous follicles. Owing to the presence
of the latter, the lower part of the nose is frequently the seat of acne.
Inflammation of the skin over the cartilaginous portion of the nose is
very painful, and is usually accompanied by local congestion, the pain
depending upon the tenseness of the part and the congestion upon the
free blood-supply of the region. ‘There is very little fat in the cellular
tissue between the skin and the alar cartilages.

The muscles in connection with the nose are, on each side,
the pyramidalis nasi, the compressor naris, the depressor alee nasi, and the
smaller dilatator muscles. The pyramidales nasi muscles arise from the
upper borders of the right and the left compressor naris muscle, having
an angular interspace between them, and pass upward over the bridge of
the nose, joining each other in the middle line, and blending their outer
fibres with the orbicular muscles of the eyelids, their inner fibres being
prolonged into the occipito-frontales muscles (Plate 15, No. 4). The
principal action of these muscles is to produce transverse wrinkles at
the root of the nose, by drawing down the inner angles of the eyebrows;
110 THE REGION OF THE NOSE AND THE NASAL CAVITIES.

but by reversing their action and tightening the skin over the alar carti-
lages they may also serve as dilators of the nostrils. The compressor
muscles of the nose are triangular in shape, arising on each side of the
face, from the inner sides of the canine fosse of the superior maxille,
and join by a common aponeurosis over the dorsum of the nose. These
muscles compress the ale and produce the pinched appearance seen in
labored breathing. Their origins are concealed by the elevator muscles
of the upper lip and the wing of the nose (Plate 18, No. 4, and
Plate 19, No. 5).

The depressores alarum nasi muscles arise from the superior maxillary
bones, above the second incisor teeth, and, being placed between the mucous
lining of the upper lip and the orbicular muscle of the mouth, their fibres
radiate to the septum and back parts of the ale of the nose. These
muscles serve to constrict the anterior nares by drawing the ale downward.

The dilatator—anterior and posterior—muscles are very delicate bundles
of fibres, which pass respectively from the alar cartilage to the overlying
skin, and from the sesamoid cartilages and nasal process of the superior
maxilla to the margin of the nostrils. In ordinary respiration, especially
in sleep, these little muscles resist the tendency of the nostrils to close from
atmospheric pressure, by raising and everting the ale, but in dyspnea their
action is marked, as it also is in the expressions of pride, anger, and disdain.

The arteries of the nose are the Jateralis nasi from the facial
(Plate 18, No. 6), the nasal branch from the superior coronary artery
to the septum, and the nasal branches from the ophthalmic and infra-
orbital arteries. The great vascularity of the skin over the nose renders
it well adapted for plastic surgery in this region. The nasal veins empty
into the facial and ophthalmic veins. The nerves of the nose are branches
from the facial nerve which supply the muscles, branches from the infra-
orbital and infra-trochlear nerves, and the naso-lobular filament from the
nasal branch of the ophthalmic, which, after descending in a groove on the
inner surface of the nasal bone, becomes subcutaneous at the junction of
the nasal bone and upper lateral cartilage and supplies the tip and lobule of
the nose (Plate 53, Fig. 1, No. 17). This latter nerve establishes connec-
tions with the eye, as is demonstrated by the lachrymation which follows
THE REGION OF THE NOSE AND THE NASAL CAVITIES. 111

any intense irritation about the nostrils. There are numerous lymphatic
vessels about the nose, which follow the course of the facial vein and mostly
empty into the lymphatic glands of the submaxillary region (Plate 16).
Within the margins of the nostrils there are numerous stiff curved hairs,
vibrisse, which grow from the inner surface of the ale and septum as far
as the place where the skin joins the mucous lining of the nasal cavities.

The nasal fossz, or nasal cavities, are the two very irregularly
shaped air-chambers, separated by the septum nasi, which open on the
face by the anterior nares and on the pharynx by the posterior nares, and
communicate at their outer sides with the sinuses of the ethmoid, sphenoid,
frontal, and superior maxillary bones. They also communicate with the
orbits by the lachrymal canals, with the mouth by the anterior palatine
canals, and with the cranium by the olfactory foramina. Each nasal fossa
is narrower above than below, and higher at the centre than at either the
anterior or the posterior opening. ‘The roof of each nasal fossa is formed
by the nasal bone, the nasal spine of the frontal bone, the cribriform plate
of the ethmoid bone, the body of the sphenoid bone, and the sphenoidal
turbinated bones. The floor is formed by the horizontal plates of the
superior maxillary and palate bones, and is wider at the centre than at
either end. The inner wall is the smooth septum formed principally by
the perpendicular plate of the ethmoid bone, the vomer, and the septal
cartilage. The outer wall is formed by the nasal processes and inner sur-
faces of the superior maxillary, lachrymal, ethmoid, palate, and inferior
turbinated bones, and the internal pterygoid plate of the sphenoid bone.
The turbinated bones are delicate, spongy, scroll-shaped bony shelves, which
give greater extent of surface to the mucous lining of the nose, pro-
jecting from the outer wall and dividing each nasal cavity into the
superior, middle, and inferior nasal meatuses, or passage-ways (Plate 12,
No. 29). The superior meatus is the smallest, and occupies the upper
and back part of the nasal fossa, between the superior and middle turbi-
nated bones. In the dried skull the spheno-palatine foramen opens at the
back part of the outer wall of the superior meatus, but in the recent
state this opening is covered by the pituitary mucous membrane. The
posterior ethmoidal cells communicate with the superior meatus imme-
developed male, aged thirty-five years.

PLATE 16.

Dissection of the superficial muscles of the right side of the head, face, neck, thorax, and arm. From a well-

The superficial lymphatic glands and vessels of the face and neck are drawn

on the photograph (after notes of many dissections) to show their arrangement and position.

1

nN

. The epicranial aponeurosis.

. The temporal muscle, with the temporal lymphatic
vessels.

. The posterior auricular lymphatic glands.

. The superficial jugular lymphatic glands.

The mastoid attachment of the sterno-cleido muscle.

. The occipital lymphatic glands and vessels.

. The splenius muscle.

. The levator anguli scapule muscle.

. The sealeni muscles.

. The trapezius muscle.

. The deltoid muscle.

. The compressor naris muscle.

. The buccinator muscle.

. The anterior auricular lymphatic glands.

. The supra-parotid lymphatic glands.

. The masseter muscle.
. The depressor anguli oris muscle.

 

18.
19.
20.
. The thyro-hyoid muscle.
. The omo-hyoid muscle.

SRRSRR

29.
30.
31.
32.
33.
34.

The submaxillary lymphatic glands.
The digastric muscle. ‘
The hyoid bone.

The pomum Adami of the thyroid cartilage.

. The carotid lymphatic glands.
. The sterno-thyroid muscle.

. The sterno-hyoid muscle.

27.
. The clavicular attachment of the sterno-mastoid mus-

The supra-clavicular lymphatic glands.

cle.
The sternal attachment of the sterno-mastoid muscle.
The clavicular portion of the pectoralis major muscle.
The sternal portion of the pectoralis major muscle.
The triceps muscle.
The serratus magnus muscle.
The biceps muscle.
THE REGION OF THE NOSE AND THE NASAL CAVITIES. 113

diately behind the superior turbinated bone in the upper wall. The
middle meatus is larger than the superior, is situated between the middle
and inferior turbinated bones, and extends along the posterior two-thirds
of the outer wall of the nasal fossa. At its anterior part a long narrow
passage, the infundibulum, leads upward into the anterior ethmoidal cells
and thence to the frontal sinus. About the centre of the outer wall is
the orifice, of variable size, which leads into the sinus of the superior
maxillary bone, the antrum of Highmore. The inferior meatus is the
space between the inferior turbinated bone and the floor of the nasal
fossa, extending the entire length of the outer wall of the nose.

The lachrymal canal, or nasal duct, which conveys the tears from the
lachrymal sac to the nose, opens into the anterior part of the inferior
meatus. The lachrymal sac occupies the groove formed by the lachrymal
bone and the nasal process of the superior maxillary bone (page 86). The
nasal duct is twelve millimetres, or about half an inch, in length, and is
directed downward, backward, and a little outward. Its opening in the in-
ferior meatus in life is guarded by a valvular fold of the mucous lining, the
valve of Hasner, and its position is two and one-half centimetres, or about
one inch, behind the opening of the nostril, and one and three-fourths centi-
metres, or three-fourths of an inch, above the floor of the nose. The pharyn-
geal opening of the Eustachian tube is behind the inferior turbinated bone
(Plate 12, No. 32). There is a great difference between the form and di-.
mensions and character of the various openings of the nasal fosse as they
exist in the dried skull and as they present themselves in the recent state.
This is chiefly dependent upon the arrangement of the Schneiderian or
pituitary membrane, the vascular mucous membrane which lines the nasal
cavities and the passages connected with them. This membrane is con-
tinuous with the skin at the inner borders of the anterior nares, with the
mucous membrane of the pharynx through the posterior nares, and with
the conjunctiva through the nasal ducts and the lachrymal canaliculi, and
is prolonged into the various sinuses communicating with-the nasal fossee
already described. A coryza, or inflammation of the nasal mucous mem-
brane, may thus implicate any of these structures, and a “cold in the

head” or an attack ‘of “hay fever” furnishes a demonstration of these
15
114 THE REGION OF THE NOSE AND THE NASAL CAVITIES.

relationships. The mucous membrane varies much in thickness, vascu-
larity, and appearance in these different parts. It is thickest and most
vascular over the turbinated bones, where it forms projections especially
in relation to the front and back part of the inferior turbinated bone,
and thus encroaches upon the dimensions of the space of the nasal cavity.
It is also quite thick on the septum, but in the intervals between the
turbinated bones and on the floor of the fosse it is thinner. The lining
membrane within the cells and sinuses is very thin and pale, and very
different from the proper lining of the nose. In the middle meatus the
opening of the infundibulum is nearly closed by a fold of the membrane,
and the opening into the antrum of Highmore is greatly diminished from
its size in the dried bone, appearing usually as a round hole, about the
centre of the middle meatus, and nearly two and one-half centimetres, or
an inch, above the floor of the nose. The mucous lining of the nasal cavi-
ties is peculiarly modified in the nostrils, in the air-passages, and in the
olfactory region. In the nostrils it is furnished with papille, a few hairs,
and a squamous epithelial lining; in the air-passages the epithelium is
columnar and ciliated; but upon the upper portion of the septum and
upon the superior and middle turbinated bones, where the olfactory nerves
are distributed, the epithelium is entirely columnar. These columnar cells
terminate in fine processes, between which the microscope reveals nucleated
fusiform cells, the so-called olfactory cells.

The anterior nares are the oval openings of the nasal cavities on the
face, and are placed horizontally, so that in order to examine the septum
and inferior turbinated bones the head should be thrown back (Plate 53,
Fig. 1). A finger can be readily introduced into the nostril and passed
far enough back to reach another finger introduced into the posterior nares
through the mouth. The posterior nares are about the same height as the
anterior (three centimetres, or one and a quarter inches), and measure trans-
versely in the dried state twelve millimetres, or about half an inch, but in
life the mucous: lining considerably diminishes them. The ordinary devi-
ation of the septum may block one nostril more or less, and interfere with
the clearness of the voice, especially in singing. The floors of the nasal
cavities are generally wider at the centre, where the passages are also
THE REGION OF THE NOSE AND THE NASAL CAVITIES. 115

higher than elsewhere, and foreign bodies often become lodged here. The
introduction of forceps to remove the latter, or for the extraction of nasal
polypi, should be along the floor of the inferior meatus, and they should
be opened so as to grasp the object vertically.

The posterior nares when the mouth is opened are usually blocked by
the folds of the soft palate being drawn upward, and are thus. cut off from
the pharynx. Owing to this disposition, the “nasal douche” can be used
so that the fluid introduced into one nostril shall pass over the soft palate
and return by the other nostril.

The vascularity of the mucous membrane of the nose is due to the
numerous capillaries which anastomose freely beneath its surface. The
arteries of the nasal cavities are the anterior and posterior ethmoidal
branches of the ophthalmic arteries, which supply the roof of the nose, the
ethmoidal cells, and the frontal sinuses; the nasal arteries, from the internal
maxillary, which supply the septum, the meatuses, and the turbinated
bones ; and the posterior dental arteries, from the internal maxillary arteries,
which supply the antra. The veins of the interior of the nose terminate in
the ethmoidal veins, which enter the ophthalmic vein. In children there
is almost always a communication between the nasal veins and the superior
longitudinal sinus through the foramen cecum. This is usually closed
about puberty, but may continue in the adult and perhaps explain per-
sistent hemorrhage or the spread of inflammation from the nasal cavities to
the meninges of the brain. There is a venous plexus (rete nast) about the
inferior turbinated bone which resembles a kind of cavernous tissue, very
prone to bleed. Bleeding from the nose—or epistaxis—is generally due
to some interference with the venous circulation. There are also venous
communications with the frontal vein, and through the spheno-palatine
foramen with the zygomatic plexus. The mucous membrane of the nose
is abundantly furnished with sensory nerves. The roof is supplied by
the nasal branches from the ophthalmic and filaments from the Vidian
nerves; the septwm, by branches from the nasal nerves, the spheno-
palatine (or Meckel’s) ganglions (Plate 3, Fig. 2, No. 6), and the naso-
palatine nerves; the floor, by branches from the naso-palatine and anterior
palatine nerves; and the ouéer walls, by filaments from the spheno-palatine
116 THE REGION OF THE FACE.

ganglions, and branches from the nasal, anterior dental, and anterior pala-
tine nerves. The olfactory nerves, about twenty on each side, are derived
from the olfactory bulbs, and pass through the foramina in the cribriform
plate of the ethmoid bone. They are arranged in three sets on each side,
and each nerve is invested with a fibrous prolongation from the dura mater.
The inner set supply the upper part of the septum; the middle are the
smallest, and are spread over the roof of the nose; the outer are the largest,
and are divided into two groups, the anterior group supplying the mucous
membrane over the superior turbinated bone, and the posterior group being
distributed over the. os planum and the middle turbinated bone. It will be
noticed that the olfactory nerves are situated high up in the nasal cavities,
and hence in the effort to smell intently the nostrils are always dilated.
The partial loss of smell in some cases of facial paralysis has been ascribed
to inability to dilate the nostrils. The olfactory nerves ramify between the
mucous membrane and the bone, communicating freely with one another,
and forming plexuses with elongated meshes. The fibres of these nerves
are non-medullated, with a sparsely nucleated neurilemma. Interspersed
between the columnar epithelial cells in the olfactory region there are
peculiar cells having a nucleated body with two processes. These are
called the olfactory cells, because one of the cell processes terminates on
the surface of the mucous membrane and the other is believed to be in
connection with the terminal filaments of the olfactory nerves.

THE REGION OF THE FACE.

The landmarks of the face (Plates 1 and 28) include, besides the
bony prominences of the orbits (page 79) and the nose (page 108), the
malar eminences and their backward prolongations into the zygomatic
arches, which support the cheeks, and the angles, lower border, and
mental eminence of the inferior maxillary bone, the latter giving promi-
nence and character to the chin.

The skin of the face is generally very fine and thin, and adherent
to the parts beneath, except over the eyelids, where it is peculiarly delicate
and the subcutaneous cellular tissue is very loose. In relation to the ale of
THE REGION OF THE FACE. nels

the nose and the chin it is more dense, and somewhat resembles the tissues
of the scalp; and over the bony prominences contused wounds are often
attended with a linear rupture of the skin similar to an incised wound.
The lax arrangement of the cellular tissue elsewhere about the face is
demonstrated in the swellings which follow inflammatory infiltration about
the cheeks and mouth. There is much fat in the subcutaneous tissue of
the face, especially in the anterior parts of the cheeks (Plates 18 and 19)
and in relation to the zygomatic muscles. In children there is an
aggregation of fatty lobules surrounded by a capsule over the buccinator
muscles, called the “sucking cushions,” because they are thought to be
instrumental in distributing the atmospheric pressure and preventing the
buccinator muscles from being pressed inward between the alveolar arches
when a vacuum is created in the mouth. The skin of the face is intimately
associated with many of the subjacent muscles, the habitual use of some
of which produces the facial furrows and markings characteristic of certain
expressions. A careful study of these lines and their varying modifica-
tions will prove of great value to the physician in forming a diagnosis
of many diseases, especially in young children and the ignorant, in whom
the facial expression is often the sole guide in the recognition of subjective
symptoms. The only way of obtaining information from an infant who
cannot communicate ideas or describe sensations by speech, is by noticing
the expression and gestures. Such observation teaches that contraction
of the brows indicates pain in the head; sharpening of the nostrils,
pain in the chest; and drawing of the upper lip, pain in the abdominal
region. There are certain lines (Jadelot’s) which become marked in the
face of any one suffering from serious diseases. Of these, the line which
begins at the inner corner of the eye and passes outward toward the
cheek-bone beneath the lower lid—the oculo-zygomatic line—is associated
with disorder of the cerebro-nervous system. The line which extends
from the wing of the nose round the corner of the mouth,—the nasal
line,—if connected with marked dimpling of the cheek, points to disorder
of the digestive tract. This is especially the case in infancy. The line
which passes from the angle of the mouth to the lower part of the face
—the labial line—is a sign of disease of the respiratory organs.
PLATE U7.

The skin removed on the left side of the neck to show the platysma myoides muscle and the usual position of the

great external jugular vein.

1. The anterior temporal artery, seen through the scalp. 8.
2. The position of the temporal artery, where it emerges 9.

from the parotid gland. 10.
3. The position of the parotid gland. 11,
4, The position of the submaxillary gland. 12,
5. The external jugular vein, showing its course from the | 18.

angle of the lower jaw to the middle of the clavicle. 14,
6. Theprominence of the thyroid cartilage(pomum Adami). | 15.
7. The platysma myoides muscle. 16.

Superficial veins over the supra-clavicular fossa,
The helix.

The fossa (ovalis) of the anti-helix.

The fossa (scaphoidea) of the helix.

The anti-helix.

The tragus.

The concha.

The anti-tragus.

The lobule.
THE REGION OF THE FACE. 119

The muscles of the face, especially those called from their action
the muscles of expression, are of finer texture and paler color than the
muscles generally in other parts of the body. The muscles of expres-
sion also have no proper tendons of origin or insertion, are destitute of
aponeuroses or sheaths, and blend with adjacent muscles by the most
complex and delicate interlacement of their fibres (Plate 15), so that
they do not present the same arrangement in every individual. They
often vary in development even on the two sides of the face, thereby’
influencing the character and degree of the expressions. The muscles of
the forehead, orbits, and nose are described with the anatomy of those
regions. The muscles which surround the mouth and are attached to
its upper and lower borders are remarkable for their interdependence
(Plate 15) and for their great mobility. The orbicularis oris muscle is,
like other sphincter muscles, composed principally of circular fibres, and
has very slight attachments to the neighboring bones. The variety in
the prominence of the lips in different individuals depends upon the
size and thickness of this muscle. It consists of two portions, each pos-
sessing very marked differences from the other in the appearance and
arrangement of its fibres. The labial portion is composed of very thin
pale fibres which surround the mouth and have no bony attachment; the
facial portion is broader, its fibres at the outer borders of the upper
and lower lips intermingling with the fibres of other muscles, which
converge toward it from the surrounding parts of the face. It is con-
nected on each side to the bone by two fasciculi in the upper lip, one to
the septum nasi and the other to the alveolar border in relation to the
incisor teeth, and by a single fasciculus on each side in the lower lip to
the lower jaw in relation to the canine tooth. There are tiny slips
extending one on each side from the orbicularis to the anterior part
of the nasal septum, producing the delicate furrow, called the philtrum,
from the nose to the upper lip. This muscle counteracts all the other
muscles which move the lips, the infinite play and variety of expression
about the mouth depending upon the counterbalancing of their opposing
actions. The ordinary action of the orbicularis closes the lips, and, on
account of the outer surface of the muscle being intimately connected
120 THE REGION OF THE FACE.

with the lips and the overlying skin, its forcible contraction produces
radiating wrinkles about the mouth in the skin of elderly persons.

The levatores labii superroris et alarum nasi muscles arise from the nasal
processes of the superior maxillary bones near the inner borders of the
orbits, and, passing downward, divide into inner slips, which are inserted
into the alar cartilages of the nose, and outer slips, which blend with the
orbicularis oris and the adjacent levatores labii superioris muscles in the
‘upper lip. These muscles serve to dilate the nostrils and to draw upward
the upper lip and the wings of the nose, and produce the changes in the
countenance in the expressions of indignation, disgust, and derision. Their
habitual use occasions the furrows which extend from the side of the nose
to the corners of the mouth. The levatores labii superioris (proprius)
muscles arise from the lower borders of the orbits beneath the orbicular
muscles of the eyelids, above the infra-orbital foramina, and, overlapping
the deep origins of the compressor nasi and levator anguli oris muscles, on
each side, their fibres blend with the orbicularis oris. The two levator
angult oris muscles arise underneath the preceding muscles from the
canine fossee of the superior maxille delow the infra-orbital foramina,
and blend at the angles of the mouth with the contiguous muscles. The
zygomaticus muscle arises on each side from the malar bone near its junc-
tion with the zygoma, and passes obliquely in a bed of fatty tissue across
the side of the face to the angle of the mouth, where its fibres interlace
with those of the other muscles of the upper lip. The action of this muscle
is seen in laughing and snarling. Sometimes an additional muscular slip
passes downward from the orbicularis palpebrarum, and, taking a course
parallel to the zygomaticus, is called the zygomaticus minor. The depressor
angult oris muscle on each side has a broad origin from the oblique line
of the inferior maxilla behind the mental foramen, and its fibres converge
upward to a narrow insertion at the angle of the mouth, where they
intermingle with those of the zygomaticus, the orbicularis oris, and the
upper portion of the platysma muscle, known as the musculus risorius
(or laughing muscle of Santorini), and also with the under strata of the
levator anguli oris. The peculiar arrangement of the interlacing of the
fibres of this muscle at the corner of the mouth with so many others
THE REGION OF THE FACE. 121

renders this part the most mobile in the face. The depressor anguli oris
is the most expressive of all the facial muscles: it plays an important
réle in melancholy and sorrowful emotions.

The depressores labti inferioris muscles arise from the lower jaw, between
the symphysis and the mental foramina, a quantity of fat being generally
interspersed among their fibres, which are inserted into the lower lip,
blending with one another and the outer portion of the orbicularis. These
muscles draw the lower lip downward and a little outward, as in the
expression of irony or sarcasm.

The levatores menti muscles arise in conical bundles from the incisor
fossee of the lower jaw, and are inserted into the skin of the lower part
of the chin. Their action is to wrinkle the chin, as in doubt, and to
raise the chin and protrude the lower lip. The latter action is made
use of in shaving the chin.

The two risortus muscles are constituted by a separation of the upper
fibres of the platysma myoides muscles, which are inserted into the super-
ficial layer of fibres from the depressor anguli oris and the orbicularis
muscles at the angles of the mouth. A few fibres of the risorius muscles
occasionally arise from the fascia over the masseter muscles. When these
are pronounced, the action of these muscles is noticeable in laughter, but
as they usually exist they produce the smile of scorn or derision rather
than that of good humor. There is often great diversity in the develop-
ment of these muscles on the two sides of the same face. Beneath the
risorius and other muscles which blend at the angles of the mouth are the
oral attachments of the buccinator muscles. These muscles are chiefly
concerned with keeping the food between the teeth during mastication,
and therefore are more properly classified with the regions of the cavity of
the mouth (page 172) and of the pharynx. They arise from the molar
portions of the alveolar processes of the upper and lower jaws, and
posteriorly from the fibrous intersections which separate them from the
superior constrictor muscles of the pharynx on each side. These fibrous
bands extend from the hamular processes of the internal pterygoid plates
to the posterior extremities of the mylo-hyoid ridge on each side of the

lower jaw, near the last molar teeth. They are called the pterygo-
16
122 THE REGION OF THE FACE.

maxillary ligaments. The fibres of the buccinator muscles pass forward,
to be inserted in a peculiar manner at the under surface of the other
muscular structures at the angles of the mouth. The upper fibres join
the upper lips, and the lower fibres the lower lips, while the central fibres
cross one another. Unlike the rest of the facial muscles, the buccinators
are covered with a sheath of fascia externally, which greatly increases
their power. In relation to the masseter muscles a quantity of fat, on
each side, fills up the zygomatic fosse, giving to the face a fulness or
roundness in these parts. Its absorption produces the sunken condition
of the cheeks in emaciated individuals. The buccinator muscles widen
the aperture of the mouth by pulling upon its corners, and their power
for expelling the air from the mouth is seen in whistling, or in blowing
a trumpet (whence their name).

The masseter muscles arise from the lower edges of the zygoma and
malar bones. These muscles consist of superficial and deep strata of fibres
arranged in a crossed manner which greatly augments their power. The
superficial fibres constitute the principal part of each muscle, and take
origin by a thick tendinous aponeurosis from the malar process of the
superior maxilla and from the lower border of the anterior two-thirds
of the zygoma (Plates 16, 18, and 21). These fibres pass obliquely
backward, and are inserted into the angle and the lower half of the outer
surface of the ramus of the jaw. The deep fibres are mainly muscular,
and arise from the posterior third of the lower border and the whole
of the inner surface of the zygomatic arch. They pass downward and
forward, and are inserted into the upper half of the ramus and the outer
surface of the coronoid process, blending with the insertion of the super-
ficial fibres. The anterior border of the muscle is therefore formed of the
two layers of fibres, and presents a thick prominence which can be readily
felt by the finger inserted in the mouth between the cheek and the malar
bone. The deep portion of this muscle is partly covered by the superficial
portion anteriorly, and it is in relation to the parotid gland posteriorly.
The masseter muscles assist largely in producing the contour of the lower
part of the face. Their function is to raise the lower jaw and to assist the
temporal muscles in mastication. There is a dense layer of fascia, derived
THE REGION OF THE FACE. 123

from the deep cervical fascia, which covers each masseter muscle, called
the masseteric fascia. It adheres intimately to the tendon of origin of the
superficial portion, and binds it firmly to the ramus of the jaw. A few
strong fibres also connect the origin of the deeper portion with the tendon
of the temporal muscle at the coronoid process. The motor nerves of the
masseter muscle are, like those of the temporal (page 14), derived from
the inferior maxillary nerve. The spot where reflex contraction of the
masseter muscle may be produced by electrical stimulation is four centi-
metres, or about an inch and a half, in front of the ear, on a line drawn
from the apex of the nose to the lobule (Plate 53, Fig. 1, No. 21).
The arteries of the face are very numerous, and are derived from
the facial, internal maxillary, and temporal. branches of the external
carotid artery. The facial (or external mazillary) artery, after it has
tunnelled through the submaxillary gland, appears at the side of the face,
coursing over the body of the lower jaw, accompanied by the facial vein
in front of the masseter muscle (Plate 18, No. 14, and Plate 19, No. 13).
In this relation the artery is comparatively superficial, and its pulsation
can be readily detected or checked by compression. In order to secure
it with a ligature the incision should be made parallel to the anterior
border of the masseter muscle, about three centimetres, or an inch and a
quarter, in front of the angle of the jaw; but it should be remembered
that the vessel usually lies in a loose bed of fat, and that the skin and
platysma muscle over it are freely movable, so that it will readily slip
aside. It may be rendered more tense by depressing the lower jaw.
From the masseter muscle the artery passes very tortuously to the corner
of the mouth, where it gives off ordinarily the inferior labial and coronary
arteries to the lips, and is continued up along the side of the nose
to the inner canthus of the eye, terminating as the angular artery
(Plate 19, No. 4). In its course over the face it gives off branches to the
masseter and buccinator muscles. The wmferior labial artery passes under
the depressor anguli oris and anastomoses with the mental, submental, and
inferior coronary arteries. The inferior coronary artery is usually given
off from the facial near the corner of the mouth, either by an independent
trunk or in common with the superior coronary. It passes beneath the
124 THE REGION OF THE FACE.

depressor anguli oris, pierces the orbicularis, and, running between this
muscle and the mucous membrane of the lip, inosculates with its fellow
and the inferior labial. and mental arteries. The superior coronary is
larger and more tortuous than the inferior, and arises from the facial
artery beneath the zygomaticus muscle. It also runs between the muscular
structure of the upper lip and the mucous membrane, and, inosculating
with its opposite fellow, forms with the two inferior coronary arteries a
vascular circle, which can be felt pulsating on the inside of the mouth
by compressing the lips anywhere near their free borders. The superior
coronary supplies branches to the septum and ala of the nose. Some-
times this vessel arises independently from the transverse facial branch
of the temporal artery (Plate 19, No. 9), which is then much enlarged
and superficial.

The lateral artery of the nose is supplied by the facial to the ala
and dorsum of the nose. It anastomoses with the nasal branch from
the ophthalmic artery, the septal artery, the infra-orbital artery, and the
communicating vessels from the other side of the nose.

The angular artery is the termination of the facial, and ascends among
the fibres of the levator labii superioris et alee nasi muscle to the inner
angle of the orbit, where it inosculates with the nasal branch of the oph-
thalmic artery in relation to the tendo palpebrarum, on the nasal side of the
lachrymal sac. The anastomoses of the facial artery are so numerous that
ligature of both ends of a divided vessel in this region is often necessary.
The great vascularity of the face occasions very rapid healing in wounds,
which should have their edges accurately adjusted as soon as possible, to
avoid distortion. The same cause also occasions the occurrence of nevi
and erectile tumors about the face. The remarkable success of plastic
surgery in this region is due to the great vitality of the flaps, and extensive
injuries involving loss of substance are often repaired rapidly.

The facial artery and its branches are surrounded by a minute plexus
of vaso-motor and dilator nerves, derived from the superior cervical gan-
glion of the sympathetic nerve (Plate 36, No. 49), to the influence of
which is probably due the sudden blushing or pallor of the countenance
which attends mental emotions, as in shame or fear.
THE REGION OF THE FACE. 125

The facial vein begins at the inner corner of the eye, where it receives
the blood from the frontal and supra-orbital veins, and is called the angular
vein where it is in relation to the angular artery. Thence it passes down
the side of the nose, with the lateral nasal artery, and from the alar
cartilage it takes an oblique course to the anterior border of the masseter
muscle, being interposed between it and the facial artery, with which it is
apt to be ensheathed (Plate 18, No. 15, Plate 19, No. 18, and Plate 21,
No. 32). It usually passes directly over the termination of the parotid
duct (Plate 18, No. 10). The veins emptying into the facial vein are the
tributary veins from the territories supplied by the branches of the facial
artery; but at the corner of the mouth it is increased in size by the
communicating veins from the infra-orbital and temporo-maxillary veins.
By far the most important of the communications of the facial vein are
the veins which bring it in relation with the cavernous sinus at the base
of the brain. This connection is twofold. There is a direct communi-
cation with the angular vein through the ophthalmic vein (page 95), and
an indirect communication through the deep facial vein, from the pterygoid
plexus, which is in relation with the cavernous sinus by small veins through
the foramen of Vesalius, in the sphenoid bone, and the fibrous tissue of the
foramen lacerum medium. There are no valves in the facial vein, or at the
junction of any of its branches, so that when it is involved in wounds the
bleeding from it is very copious. It is also peculiar in remaining more
patent after being cut than superficial veins elsewhere, which renders it
liable to septic absorption. The facial vein terminates in the internal
jugular vein near the bifurcation of the common carotid artery. The
lymphatic vessels of the face converge chiefly toward the submaxillary
ganglia, while some go to a few lymphatic ganglia which lie superficially
over the parotid gland (Plate 16).

The sensory nerves of the face are mainly derived from the
terminal branches of the fifth cranial, or trifacial, nerve (Plate 3, Fig. 2).
An accurate knowledge of the position of the foramina through which they
make their exits upon the face (Plate 28), and of their cutaneous areas
of distribution (Plate 53, Fig. 1), is of the greatest value in determining
the seat and treatment of neuralgic affections in this region. The oph-
Won no Wt

Hee
ones

14.
15.
16.
17.

18.
19.
20.
21.
22:

23.
24.

PLATE 18.

The superficial fascia removed from the left side of the face, together with the platysma myoides muscle from the
neck, to show the superficial vessels and nerves in these regions, and especially the superficial relations of the parotid
gland.

. The supra-orbital artery.

. The anterior branch of the temporal artery.

. The angular artery.

. The compressor naris muscle.

. The levator labii superioris muscle.

. The lateral nasal artery and vein.

. The levator anguli oris muscle.

. The zygomaticus major muscle.

. The transverse facial artery.

. The duct of Stenson, from the parotid gland.

. The infra-orbital branches of the facial nerve.
. The orbicularis oris muscle.

. The inferior labial artery (arising in this case from the

transverse facial artery).

The facial artery.

The facial vein.

The depressor labii inferioris muscle.

The submaxillary vein, joining the facial vein with the
external jugular vein.

The anterior belly of the digastric muscle.

The mylo-hyoid muscle.

The submaxillary gland.

The facial branch of the auricularis magnus nerve.

The oblique vein, joining the facial vein with the in-
ternal jugular vein.

The point of bifurcation of the common carotid artery.

The thyroid notch (pomum Adami).

 

32.

SRES

47.

. Superficial branches of the superior thyroid artery.

. The superficial transverse cervical nerves.

. The left sterno-thyroid muscle.

. The left sterno-hyoid muscle.

. The fascia over the supra-clavicular fossa.

. The sternal portion of the sterno-cleido-mastoid muscle.
. The clavicular portion of the sterno-cleido-mastoid

muscle.
The sternal and clavicular nerves, from the cervical
plexus of nerves.

. The fascia over the clavicle.

. The fascia over the great pectoral muscle.
. The superficial temporal nerves.

. The auriculo-temporal nerve.

37.
38.
39.
40.
41.
. The mastoid branch of the auricularis magnus nerve.
43.
. The external and internal carotid arteries covered by

The temporal artery.

The orbital branch of the temporal artery.

The temporal branches of the facial nerve.

The parotid gland.

The auricular branch of the auricularis magnus nerve.

The external jugular vein in its proper position.

their sheaths of the deep fascia.

. The auricularis magnus nerve.
46.

The junction of the superficial cervical veins with the
external jugular vein.
The acromial nerve.
Platel8& ; Vowel

 

Heht89/)py GeoreeMc Cer anM.D.

 

Dissected, Photographed and C

 

Jored From |

   
THE REGION OF THE FACE. 127

thalmic division of the trifacial nerve supplies the supra-orbital, the supra-
trochlear, the lachrymal, the infra-trochlear, and the naso-lobular, all of
which have been described with their special regions.

The superior mazillary division of the trifacial nerve terminates upon
the face in the infra-orbital nerve and the temporo-malar nerve, the
former of which emerges, with the infra-orbital artery, from the infra-
orbital foramen under the levator labii superioris muscle. The infra-orbital
foramen is six millimetres, or about a quarter of an inch, below the margin
of the orbit, and directly in a straight line drawn from the supra-orbital
foramen, which is three centimetres, or an inch and a quarter, from the
external angular process, toward the root of the nose, to the mental
foramen, which is the same distance outward from the symphysis of
the lower jaw. The location of this foramen is of surgical importance,
as the nerve is apt to be compressed within its bony canal. The foramen
may be reached by a trap-door incision made parallel to the lower
margin of the orbit, over the point just indicated. The infra-orbital
canal, in which the nerve is lodged before it makes its exit at the
foramen, presents considerable variations, so that the operation for resection
of the nerve is better done by seeking the foramen first, and then chiselling
away the bone so as to expose the nerve in the anterior part of its course.
In close relation to the infra-orbital foramen is the plexus formed by the
communications between the deep branches of the facial nerve, which sup-
plies the adjacent muscles, and the descending branches of the infra-orbital
nerve. Immediately after issuing from the foramen, the nerve separates
into a leash of fibres, some of which, the palpebral, pass upward beneath
the orbicularis palpebrarum muscle to supply the lower eyelid; others, the
nasal, pass to the side of the nose; and others, the dadial, and the most
numerous, descend beneath the levator labii superioris muscle and termi-
nate in the papille of the upper lip and the bordering mucous mem-
brane of the mouth. The ¢emporo-malar nerve arises from the superior
maxillary nerve within the spheno-maxillary fossa, whence it enters the
orbit and divides into temporal and malar branches. The temporal branch
runs in a groove in the malar portion of the orbit and passes through a
foramen in the malar bone. It ascends under the temporal muscle, which
128 THE REGION OF THE FACE.

it pierces, together with its fascia, about two and a half centimetres, or an
inch, above the zygoma, and is distributed to the skin of the temple and
side of the forehead (Plate 53, Fig. 1, No. 20). The malar branch issues
on the face through a foramen in the malar bone, of variable size and
position, and, piercing the outer fibres of the orbicularis palpebrarum
muscle, supplies the skin of the cheek over the malar bone, being some-
times called the subcutaneus male.

The sensory portion of the inferior maxillary division of the trifacial
nerve terminates upon the face in the awriculo-temporal nerve, the buccal
nerve, and the mental nerve. The auriculo-temporal nerve arises by two
roots, which surround the middle meningeal artery (Plate 3, Fig. 2,
No. 20), and then combine to form a single trunk, which passes behind
the external pterygoid muscle and the neck of the lower jaw. It first
ascends beneath the parotid gland, and then passes, with the temporal
artery and vein, over the root of the zygoma and divides into anterior and
posterior branches (Plate 18, No. 36, and Plate 19, No. 20). The anterior
branch supplies the skin over the vertex and the temporal region; the
posterior branch supplies the upper part of the pinna and the adjacent
integument. The auriculo-temporal nerve communicates, near its origin,
with the otic ganglion. It sends auricular branches to the meatus
externus and the membrana tympani (page 65), and to the tragus and
auricle. It also sends branches to the temporo-maxillary joint and to
the parotid gland. The buccal nerve arises usually in common with the
anterior deep temporal nerve, and passes either above or between the fibres
of the external pterygoid and temporal muscles to reach the buccinator
muscle, where its filaments spread out and form with the buccal branches
of the facial nerve a plexus in relation to the facial vein. The buccal
nerve supplies sensation to the skin, the mucous membrane, and the buccal
glands of the cheek. This is borne out by several instances where this
nerve has been found to originate from the superior maxillary nerve. The
facial nerve incites the motor power of the buccinator muscle by a special
branch (page 130). The mental nerve is the termination of the inferior
dental branch of the inferior maxillary nerve, which emerges, with the
mental artery, at the mental foramen in the lower jaw, beneath the
THE REGION OF THE FACE. 129

depressor anguli oris muscle. It divides into a leash of fibres, some
of which supply the integument over the chin, and the rest are dis-
tributed to the papillae and mucous membrane of the lower lip. The
skin covering the parotid gland and contiguous part of the cheek is
supplied with sensation by the great auricular branch of the cervical
plexus of nerves (Plate 53, Fig. 1, No. 27).

The motor nerves of the face are derived from the branches of the
seventh cranial or facial nerve, which emerge at the anterior border of
the parotid gland over the masseter muscle. The origin of the facial
nerve, from the lateral tract of the medulla oblongata (page 41), and its
course through the aqueduct of Fallopius in the temporal bone (page 69)
to its exit from the skull at the stylo-mastoid foramen, have been de-
scribed. After issuing from the foramen the facial nerve sends off motor
branches to the posterior auricular, occipital, digastric, and stylo-hyoid
muscles, and then, in relation to the ramus of the lower jaw, divides
into two primary facial branches, named, from their distribution, the
temporo-facial and cervico-facial nerves, which form, by their communi-
cations within the substance of the parotid gland, the plexus called by
the old anatomists the pes anserinus (Plate 19, No. 23), from its fancied
resemblance to the outspread skeleton of a goose’s foot.

The temporo-facial nerve is the largest, and in passing through the
parotid gland it crosses the external carotid artery and the neck of the jaw.
It is joined by several sensory twigs from the auriculo-temporal branch
of the trifacial nerve, and divides into temporal, malar, and infra-orbital
branches. The motor temporal nerves ascend over the zygoma and supply
the muscles about the orbit and eyelids, and form sensory connections with
the supra-orbital nerve, with the temporal branch of the superior maxillary
nerve, and with the auriculo-temporal and lachrymal nerves. The spot
where reflex contraction of the temporal muscle may be produced is two
and a half centimetres, or about an inch, in front of the ear, on a line
drawn from the eyebrow to the top of the auricle (Plate 53, Fig. 1, No. 6).
The motor malar nerves cross the malar bone to the outer angle of the orbit,
supplying the contiguous portion of the orbicularis muscle, and join with

sensory filaments from the lachrymal, supra-orbital, and subcutaneus malee
17
130 THE REGION OF THE PAROTID GLAND.

nerves. The motor infra-orbital nerves are comparatively of larger size,
and consist of superficial and deep branches which pass forward over the
masseter muscle to be distributed to the muscles beneath the lower margin
of the orbit and about the mouth. The superficial branches supply the
superficial muscles of the face and form sensory connections with the nasal
and infra-trochlear nerves along the nose. The deep branches pass beneath
the zygomaticus and levator labii superioris muscles, which they supply,
and establish sensory connections with the infra-orbital branches of
the superior maxillary nerve, forming the infra-orbital plexus, already
mentioned. The cervico-facial nerve is joined within the parotid gland
by sensory filaments from the auricularis magnus branch of the cervical
plexus of nerves. It descends toward the angle of the jaw, and divides
into the buccal, supra-maxillary, and infra-maxillary nerves. The motor
buccal nerves pass over the masseter muscle to supply the buccinator and
orbicularis oris muscles. They join with filaments of the infra-orbital
motor nerves, and form sensory connections with the buccal branch of the
inferior maxillary nerve. The supra-mazillary, nerves pass beneath the
platysma and depressor anguli oris muscles, which they supply. They
establish sensory communications with the mental branch of the inferior
maxillary nerve. The infra-maaillary nerves consist of several arching
branches beneath the platysma muscle, which they supply, between the
jaw and the hyoid bone. One of these branches is joined by the super-
ficial cervical nerve from the cervical plexus (Plate 19, No. 27).

o

THE REGION OF THE PAROTID GLAND.

The parotid gland, so called because it is near the ear (Plates 13
and 18), is the largest of the salivary glands. It weighs from half an
ounce to an ounce in different individuals, and is lodged in a pyramidal bed
upon the side of the face, below and in front of the ear. Its external sur-
face is firmly bound down by an extension of the fascia from the masseter
muscle, which is here called the parotid fascia, and which serves to conceal
the form of the gland from external view. The tough and unyielding
nature of this fascia accounts for the intense pain often experienced in cases
THE REGION OF THE PAROTID GLAND. 131

of abscesses involving the gland, or in parotitis (mumps), from pressure
upon the sensory nerves within the gland. From the inner layer of the
parotid fascia prolongations extend into the substance of the gland, which
partition off and support the lobules, the gland being of the compound
racemose variety. The lobules consist of aggregations of small cecal
dilatations (the alveoli) of fine canals, which are lined with a layer of
epithelial cells, and supported by the connective tissue which is continued
inward from the surface of the gland, as above mentioned. The peri-
lobular tissue contains lymph-spaces, which are in relation to the capillary
vessels and ultimate nerve filaments which preside over the nourishment
and secretory functions of the glandular structure. The canals are the
excretory ducts of the lobules, which empty into the main duct of the
gland, called the duct of Stenson, which leaves the gland at its anterior
border on the masseter muscle. Stenson’s duct is a firm white tube, the
size of a goose-quill, and takes a parallel course to the zygoma in close:
relation to the transverse facial artery, on a line drawn from the external
auditory meatus to a point midway between the ala of the nose and the
angle of the mouth (Plate 18, No. 10). About the middle of this line
the duct, after passing over the facial vein, turns abruptly inward around
the anterior border of the masseter muscle and penetrates the buccal fat
and the buccinator muscle, to open upon the mucous membrane of the
mouth, opposite the second molar tooth of the upper jaw, by a narrow
orifice. The saliva secreted by the parotid gland is an alkaline, watery
fluid, which aids in the mechanical disintegration of the food and also
possesses the property of converting starch into dextrin and grape sugar.

The space which the gland occupies is bounded above by the zygoma,
below by the sterno-mastoid and digastric muscles, behind by the external
auditory meatus and the mastoid process of the temporal bone. ‘The gland
is prolonged anteriorly over the ramus of the jaw and masseter muscle to
a variable extent. It is often continuous with the structure of the sub-
maxillary gland, but is usually separated from it by a fold of the deep
cervical fascia, called the stylo-maxillary ligament. ‘There is also an
extension of the deep cervical fascia which is connected with the sheaths
of the pterygoid muscles and the pterygoid process of the sphenoid bone.
15.
16.

17.
18.

PLATE 19.

The parotid gland removed from the left side of the face to show the branches of the facial nerve, and the fascia
removed from the posterior cervical triangle to show more clearly the superficial cervical plexus of nerves.

. The frontal muscle and branches of the frontal artery

and supra-trochlear nerve.

. The supra-orbital artery and nerve.
. The anterior branch of the temporal artery.

The angular artery.
The compressor naris muscle.

. The lateral nasal artery and vein.
. The levator anguli oris muscle.

The zygomaticus major muscle.

. The transverse facial artery.

. The masseter muscle.

. The superior coronary artery.

. The inferior coronary artery.

. The facial artery and vein.

. The depressor anguli oris muscle.

The carotid artery covered by its sheath.

The transverse cervical nerve, passing beneath the
external jugular vein.

The sterno-hyoid muscle.

The interspace between the sternal and clavicular por-
tions of the sterno-mastoid muscle.

 

19.
20.
21.
22,
23.

24,
25.
26
27.
28.
29,
30.
31.
32,

33.
34,
35.

The posterior branch of the temporal artery,

The auriculo-temporal nerve.

The temporal branches of the facial nerve.

The temporal artery.

The remains of the parotid gland, dissected away to
Show the relations of the facial nerve, and the pes
anserinus,

The vessels and nerves to the buccinator muscle.

The splenius capitis muscle,

. The auricularis magnus nerve.

The cervical branch of the facial nerve,

The occipital artery.

The trapezius muscle.

The occipitalis minor nerve.

The spinal accessory nerve.

The descending cervical nerves (sternal, clavicular,
and acromial branches).

The scalenus medius muscle.

The external jugular vein.

The supra-clavicular fossa, occupied with fat and
superficial veins.

N. B.—The transverse facial artery in this instance supplies the coronary arteries which usually arise from the facial
artery proper.
Platel9 I

 

 

 

   

Va

   

Dissected tographed and Colored From Nature by Georce Mc. CLELLAN, wv
THE REGION OF THE PAROTID GLAND. 133

The gland is therefore in a measure enclosed in a fascial envelope. This
is normally very thin over the deeper parts, but when the gland is affected
with any chronic morbid enlargement it is thickened, and may be then
more properly regarded as a sac. There is, furthermore, a peculiar in-
vagination of the deep cervical fascia between the anterior surface of the
styloid process and the posterior border of the external pterygoid muscle,
which reaches to the wall of the pharynx, so that in post-pharyngeal
abscess there is often an external swelling in the parotid region. In
several cases in the author’s experience, where the pharyngeal abscess
was so large that it was feared the evacuation of the pus through direct
incision by the mouth might lead to suffocation by its entering the glottis,
external drainage was established by careful dissection down to the stylo-
maxillary ligament and tapping the space above referred to just below
the lower border of the parotid gland.

The dimensions of the space occupied by the gland vary with the
movements of the lower jaw, and with the changes in its angle peculiar
to infancy and to old age. In the two latter instances it is naturally
increased at its lower part, owing to the obliquity of the angle, and it is
also increased when the head is extended and the jaw moved forward.
When the head is flexed it is diminished.

The relations of the parotid gland are of the greatest importance from
a surgical point of view, as its removal, when diseased, is one of the most
difficult and hazardous of surgical undertakings. The skin and superficial
fascia over this region are loose and movable, and contain some fibres of the
platysma muscle in the lower part. In the connective tissue between the
superficial fuscia and the deep or parotid fascia there are a few branches
of the superficial cervical plexus of nerves, and several lymphatic glands,
which receive the lymphatic vessels from the neighboring portion of the
scalp and the superficial tissues of the face (Plate 16). These are the
extra-parolid lymphatic glands, the enlargement of which by disease consti-
tutes a form of false parotid tumor. There is another species of lymphatic
tumor in this region which is very difficult to distinguish from enlargement
of the gland itself, owing to the involvement of the intra-parotid lymphatic
glands. These are usually two or three in number, though sometimes
134 THE REGION OF THE PAROTID GLAND.

only one, and receive the lymph from the deep temporal and maxillary
structures accompanying the vessels into the interlobular spaces within
the gland.

The deep surface of the parotid gland is very irregular, consisting of
projections of its substance which fit into the spaces between the subjacent
parts. These projections, which extend from the main body of the gland,
are known respectively as the glenoid lobe, which is received into the
portion of the glenoid fossa of the temporal bone not occupied by the
condyle of the lower jaw, and limited anteriorly by the Glaserian fissure
and posteriorly by the vaginal process; the pterygoid lobe, which projects
behind the ramus of the jaw, between the two pterygoid muscles and
internal to the internal maxillary artery; the carotid lobe, which is in
relation to the base of the styloid process, and interposed between the
external carotid artery and the internal carotid artery and internal jugular
vein; and the masseteric lobe, or socia parotidis, which is of variable size,
and lies upon the masseter muscle, usually above Stenson’s duct, into which
it opens by a separate duct. ,

The external carotid artery, at the angle of the jaw, gives off the
posterior auricular artery and continues upward under the parotid gland
for about two-thirds of its extent, and opposite the neck of the jaw it
enters the gland, and, tunnelling through its substance, emerges at the
upper border, where it is called the ¢emporal artery. Just before quitting
the gland the external carotid gives off the internal mazillary artery,
which passes behind the ramus of the jaw; while the temporal artery in
immediate relation with the upper border of the gland sends off the
transverse facial branch (Plate 18, No. 9). The lower part of the internal
surface of the gland is separated from the external carotid artery by the
confluence of the temporal and internal maxillary and posterior auricular
veins, which empty into the external jugular vein at its commencement in
the neighborhood of the angle of the jaw. The upper part of the gland,
through which the external carotid artery passes, is in immediate relation
with the internal carotid artery and the internal jugular vein (Plate 22,
Fig. 2), and interior to these vessels are the pneumogastric, spinal accessory,
hypoglossal, and glosso-pharyngeal nerves (Plate 36). The facial nerve
THE REGION OF THE PAROTID GLAND. 135

enters the parotid gland at its posterior border, on a line with the entrance
of the external carotid artery, and divides into the temporo-facial and
cervico-facial nerves, which, branching between the lobules of the gland,
form the pes anserinus, and emerge at the superior and anterior borders, to
be distributed to the region of the face (page 129). The auriculo-temporal
branch of the inferior maxillary nerve penetrates the gland behind the
neck of the jaw, and the auriculo-parotidian branch of the auricularis
magnus nerve, from the cervical plexus, enters it near the lobule of the
ear (Plate 19, No. 20). Both of these nerves supply sensation and form
connections with the facial nerve within the substance of the gland; and
in rapidly-growing tumors of the gland, not only is facial paralysis apt
to occur from pressure on the facial nerve, but the pain is often referred
to the parts supplied by the auriculo-temporal nerve, viz..—the pinna, the
temple, the meatus, and the temporo-maxillary joint.

From the above description it will be understood that it is the upper
part of the gland which extends most deeply toward the base of the skull
and involves structures of vital importance.

In some dissections the inward projections of the gland have been found
to reach such a depth, and their adhesions to be so general to hard and soft
structures alike, that an enucleation or extirpation of the entire glandular
mass would seem to be a well-nigh impossible task; but it has not proved
such in the hands of some bold enough to undertake it, and their success
has been due to the most exact knowledge of this complex region, alike in
its normal condition and in the possible changes which disease may occasion
in the parts, a precision of knowledge which is probably required by no
other operation in surgery. The tendency of most morbid growths of
the gland is outward, in spite of the resistance of the parotid fascia, and
the deep portion, although the fascia over it may be thickened by in-
flammation, is apparently drawn forward. This statement is based upon
the author’s clinical observation, and the opportunity afforded him of
examining a scirrhous parotid on the dissecting-table. The cavity of the
wound after complete extirpation of the parotid was found to be larger
at the bottom than at the surface. The styloid process, quite uncovered
by the removal of the little muscles which are attached to it, projected
136 THE DEEP STRUCTURES OF THE FACE.

into the back part of the cavity; and the internal carotid artery and
internal jugular vein, with the hypoglossal, glosso-pharyngeal, and pneu-
mogastric nerves, were at the bottom of the wound, covered by a thin
layer of fascia.

THE DEEP STRUCTURES OF THE FACE.

The deep structures of the face, included in the pterygo-maxillary
and superior maxillary regions, are of great surgical interest, owing to the
importance of their relations and connections. The external landmarks of
the pterygo-maxillary region (Plates 1 and 28) are the prominences of the
zygoma and lower jaw. Within the mouth the finger can detect, through
the mucous membrane, the contour of the ramus of the jaw and its coronoid
process and their relations to the external pterygoid plate of the sphenoid
bone. The zygoma is subcutaneous, and its prominence depends upon the
development of the malar bone, the buttress of the cheek. The attachment
of the superficial and deep fibres of the masseter muscle to the under and
inner surface of the zygomatic arch have been described (page 122), as have
also the relations of the transverse facial artery, the duct of Stenson, and.
the branches of the facial nerve, which radiate from the anterior border of
the parotid gland (page 1381). Under these parts, surrounded by some loose
fat, is the coronoid process of the lower jaw, with the insertion of the tem-
poral muscle (page 14). The sigmoid notch separates the coronoid process
from the condyle of the jaw, which articulates with the anterior portion of
the glenoid cavity of the temporal bone, forming the temporo-mazillary joint.
This is an arthrodial joint, and is provided with an inter-articular fibro-
cartilage, which is of oval form and thicker at its margin than at its centre.
Between the fibro-cartilage and the glenoid cavity there is a pouch of
synovial membrane, and interposed between the fibro-cartilage and the
condyle of the jaw is another, smaller pouch of synovial membrane. Some-
times these pouches are connected through a deficiency in the centre of the
fibro-cartilage. The fibro-cartilage serves as a buffer to prevent shock in
the violent closing of the jaws and thus ward off injury to the brain
through the thin bony plate of the glenoid cavity.
THE DEEP STRUCTURES OF THE FACE. 137

There are two lateral ligaments,—a short, external ligament, extending
from the tubercle of the zygoma to the outer and posterior borders of the
neck of the jaw, and a long, flat, internal ligament, which extends from the
spinous process of the sphenoid bone to the inner border of the dental
foramen on the inside of the ramus of the jaw. This ligament is more
properly a layer of fascia which protects the internal maxillary vessels and
the auriculo-temporal nerve from pressure by the contraction of the ptery-
goid muscles in the movements of the lower jaw.

The so-called capsular ligament consists of a few fibres which arise from
the margin of the glenoid cavity and blend below with the lateral liga-
ments, mainly at their posterior parts. The nerves to this joint are derived
from the auriculo-temporal, which is in close connection with the neck of
the capsule and the masseteric branch of the inferior maxillary nerves.

The form of this articulation admits of motion from side to side, as
well as upward, downward, forward, and backward, so as to enable the
teeth thoroughly to triturate the food. The lower jaw is elevated mainly
by the temporal and masseter muscles, with the assistance of the internal
pterygoid muscle. The fibro-cartilage holds its proper relation to the
condyle in all the ordinary movements of the jaw, but if depression is
carried to too great an extent, as in the act of yawning, forward disloca-
tion of the jaw may occur. The articular eminence at the under part
of the zygoma is coated with cartilage, is in contact with the fibro-
cartilage of the joint in front, and ordinarily the condyle never reaches
the top of the eminence, although it glides forward when the mouth is
widely opened. If, however, the depression of the lower jaw is strained
in this position, the external pterygoid muscle contracts forcibly and
draws the condyle over the eminence into the zygomatic fossa, leaving the
fibro-cartilage behind. The condyle at once becomes more or less fixed
in its new position by the action of the elevator muscles. A proper
understanding of the mechanism of this displacement is necessary for its
reduction, which demands that the lower jaw should be drawn forward,
forcibly depressed, and then pushed backward and upward. The posterior
surface of the neck and the upper portion of the ramus of the lower jaw

are embraced by the parotid gland, the pterygoid and carotid lobes of
18
138 THE DEEP STRUCTURES OF THE FACE.

which are projected inward toward the base of the skull (page 134). The
connections of the deep parts beneath the inferior maxillary articulation
are so intimate that they offer great difficulty to the dissector bent upon
investigating the diverse branches of the internal maxillary artery and
their relations to the complex nerves which traverse this region. These
can be properly displayed only after removal of the zygoma and the ramus
of the jaw (Plate 22; Fig. 2); but before this is done the attachments of
the pterygoid muscles should be understood.

The external pterygoid muscle has a double origin, the upper head
arising from the bony surface extending from the ridge on the great wing
of the sphenoid bone to the base of the pterygoid process, and the lower
head from the outer surface of the external pterygoid plate. The fibres
composing these two portions converge to be attached to the front of the
neck of the lower jaw and inserted into the fibro-cartilage above the
condyle. The internal pterygoid muscle arises mainly from the pterygoid
fossa, receiving slips from the adjacent tuberosities of the palate and
superior maxillary bones. The internal pterygoid muscle closely resembles
the masseter in form and in the direction of its fibres, which are inserted
by‘ a strong, broad tendon into the inner side of the ramus of the lower
jaw, between the dental foramen and the angle. At their origins the
pterygoid muscles rest upon and cross each other. When the muscles
upon both sides of the head act in unison the lower jaw is drawn forward,
so as to advance the lower teeth beyond the upper; when they act in
alternation they serve as the direct agents in the trituration of food.
The motor nerves to both of the pterygoid muscles are derived from
the inferior maxillary nerve, like those to the masseter and temporal
muscles. Trismus, or spasm, is very apt to affect the muscles of masti-
cation, and may be produced by irritation of the sensory branches of
the inferior maxillary nerve. The outer surface of the internal pterygoid
muscle is in close relation with the internal lateral ligament of the
temporo-maxillary joint, and its inner surface is associated with the
tensor palati muscle, and is separated from the pharynx by a cellular
space. Between the maxillary insertions of the two pterygoid muscles
pass the vessels and nerves.
THE DEEP STRUCTURES OF THE FACE. 139

The internal mazillary artery arises from the external carotid artery
in the substance of the parotid gland (page 130), opposite the neck of
the lower jaw. It is very complex in its course, supplying numerous
branches which establish free anastomoses with other arteries of the face
and head (Plate 3, Fig. 2, and Plate 22, Fig. 2). In relation to the
neck of the jaw, and between it and the internal lateral ligament, the
artery just after its origin sends off the tympanic, middle and _ lesser
meningeal, and inferior dental branches.

The tympanic artery enters the Glaserian fissure behind the articu-
lation of the jaw, to supply the cavity of the tympanum and the membrana
tympani, as described in the region of the ear. It also sometimes sends a
little branch through a foramen in the anterior wall of the external
auditory meatus, to supply the skin lining that canal. The middle menin-
geal artery ascends behind the external pterygoid muscle and enters the
foramen spinosum of the sphenoid bone, whence it passes to the anterior
inferior angle of the parietal bone and subdivides into radiating branches
between the dura mater and the parietes of the skull (Plate 9, Fig. 2).
The lesser meningeal artery usually arises independently from the internal
maxillary, although it is often a branch of the middle meningeal. : It
enters the foramen ovale of the sphenoid bone, which also gives exit to
the inferior maxillary nerve, and supplies chiefly the Gasserian ganglion
of the trifacial nerve. The inferior dental artery descends to the dental
foramen at the middle of the inner surface of the ramus of the jaw,
which it enters with the dental nerve, and, passing through a canal in
the diploic structure of the jaw, supplies the roots of all the teeth, eventu-
ally making its exit upon the face at the mental foramen (page 127) and
becoming the mental artery. Before the inferior dental artery enters the
dental foramen the mylo-hyoid branch is given off, accompanying the
corresponding nerve to the mylo-hyoid muscle. In relation to the ex-
ternal pterygoid muscle the internal maxillary artery is very tortuous.
It passes either over or under the muscle (in some cases through it), and
subdivides into the masseteric, anterior and posterior deep temporal, ex-
ternal and internal pterygoid, and buccal branches. The masseteric artery
passes outward through the sigmoid notch of the jaw to the under surface
the

SLON AMS w

be

H
a

18.

19.
20.

21,

22;

PLATE 20.

Dissection of the vessels and nerves of the scalp and face on the left side, and the sterno-mastoid muscle removed
from its sternal and clavicular attachments to display the deep cervical plexus of nerves. The fascial slip to the centre
of the omo-hyoid muscle is also removed to show the relations of the common carotid artery and the internal jugular
vein.

. The anterior branch of the temporal artery.

The angular artery.
The compressor naris muscle.

. The lateral nasal artery and vein.
. The levator labii superioris muscle.

The zygomaticus major muscle.
The orbicularis oris muscle.

. The transverse facial artery.

. The infra-orbital branch of the facial nerve.

. The facial vein.

. The facial artery.

. The depressor Jabii inferioris muscle.

. The body of the lower jaw.

. The sub-meutal artery.

. The anterior belly of the digastric muscle.

. The mylo-hyoid muscle.

. The facial artery, coming out of the submaxillary

gland, in front of the masseter muscle.

The submaxillary vein, connecting the facial vein with
the external jugular vein.

The position of the hyoid bone.

The oblique vein, connecting the facial vein with the
internal jugular vein.

The external carotid artery, just above its origin, and
slightly enlarged, as it is often found to be here.

The internal jugular vein.

. The internal carotid artery. covered by its sheath.
. The superior laryngeal artery.

. The thyroid notch.

. The anterior belly of the omo-hyoid muscle.

. The left sterno-hyoid muscle.

28. The left sterno-thyroid muscle.

31.
32.

33.
34.

. The phrenic nerve.
. The pneumogastric nerve, brought forward into promi-

nence.

The scalenus anticus muscle.

The junction of the external and internal jugular veins
with the subclavian vein.

The clavicle.

The inter-muscular cleft between the great pectoral
and deltoid muscles.

. The pectoralis major muscle.

 

36.
37.
38.
39.
40.
41,
42.
43.
44,
45,
46.
47,
48.

49,
50.
51.

52.
53.
54,
5d.
56.
57.
58.

; 80.
60.

61.
62.
63.
64.
65.
66.
67.
68.
69.
70.

ay

The posterior branch of the temporal artery.

The temporal artery.

The auriculo-temporal nerve.

The superficial temporal nerves.

The temporal branch of the facial nerve.

The upper border of the parotid gland.

The superior auricular muscle.

The remains of the parotid gland.

The masseter muscle.

The posterior auricular artery.

The temporal vein.

The posterior auricular nerve.

The external jugular vein, drawn aside, with the upper
portion of the sterno-mastoid muscle.

The submaxillary gland.

The occipital artery.

The upper portion of the sterno-mastoid muscle drawn
outward.

The second cervical nerve,

The anterior branch of the second cervical nerve.

The mastoid nerve.

The third cervical nerve.

The nerve to the levator anguli scapule muscle.

The anterior branch of the third cervical nerve.

The anastomosing branch of the second cervical nerve,
with the spinal accessory nerve.

The fourth cervical nerve.

The scalenus medius muscle, with the ascending cervi-
cal artery.

The acromial nerve from the fourth cervical nerve.

The trapezius muscie.

The clavicular nerve from the fourth cervical nerve.

The sterna] nerve from the fourth cervical nerve.

The transversalis colli artery.

The posterior belly of the omo-hyoid muscle,

The brachial plexus of nerves.

The supra-scapular artery.

The point of entrance of the thoracic duct.

The point of entrance of the external jugular vein with
the subclavian vein.

The fascia over the deltoid muscle.
 

7, Photographed and (

olored trom Nature by

Georse Mc. Ciet.an, MD,

 

 

Copyright (891 by GeoreeMc. Cuett an, M.D,

Von I

 
THE DEEP STRUCTURES OF THE FACE. 141

of the masseter muscle; the deep temporal arteries ascend to the under
surface of the temporal muscle; the pterygoid arteries supply the pterygoid
muscles; and the buccal artery passes with the buccal nerve to the bucci-
nator muscle. After leaving the external pterygoid muscle the internal
maxillary artery is continued through the spheno-maxillary fossa, where
it gives off many terminal branches.

At the tuberosity of the superior maxillary bone the superior dental
artery is distributed by minute twigs to the pulps of the molar and
bicuspid teeth of the upper jaw, and to the contiguous portions of the
gums and the antrum of Highmore. The wfra-orbital artery passes
upward through the spheno-maxillary fissure and enters the canal with
the infra-orbital nerve, which it accompanies in its distribution, to emerge
upon the face at the infra-orbital foramen (Plate 3, Fig. 2, No. 8).
Within the canal the anterior dental branches descend to the incisor and
canine teeth, and filaments ascend to the inferior oblique and rectus muscles,
as well as to the lachrymal gland. The descending palatine artery, com-
paratively large, enters the posterior palatine canal with the palatine
nerve from Meckel’s ganglion, and runs along the roof of the mouth in
close relation to the alveoli supplying the gums, the glands, and the mucous
membrane over the soft and the hard palate (Plate 13, Fig. 4, No. 12).

The Vidian artery accompanies the Vidian nerve. It is not constant,
and is always insignificant. The pterygo-palatine artery passes through
the canal from which it receives its name, and supplies the Eustachian
tube particularly. The nasal, or spheno-palatine, artery enters the nose
with the nerve of the same name from Meckel’s ganglion, supplying the
ethmoidal cells, the turbinated bones, and the antrum, and terminates as
the septal artery. It is noteworthy that the branches of the internal
maxillary artery in the first and the last part of its course pass through
bony canals, but that the branches from the intervening part go directly
to muscles.

The internal maxillary vein is formed by the veins which bring back
the waste blood from the territories supplied by the corresponding branches
of the internal maxillary artery. These tributaries form a plexus—the
pterygoid pleaus—in the space between the temporal and external pterygoid
142 THE DEEP STRUCTURES OF THE FACE.

muscles, which establishes communications with the cavernous sinus above,
at the base of the brain, and anteriorly with the facial vein. The vein
unites with the temporal vein in the substance of the parotid gland, and
they empty together into the external jugular vein.

The nerves which accompany the superior maxillary branches of
the internal maxillary artery in their distribution are branches of the
superior maxillary nerve, which is the sécond division of the fifth cranial
or trifacial nerve. It leaves the skull through the foramen rotundum,
passes horizontally forward across the spheno-maxillary fossa, and enters
the orbit by the fissure of the same name. Within the spheno-maxillary
fossa and just below the superior maxillary nerve is situated the spheno-
palatine or Meckel’s ganglion (Plate 3, Fig. 2, No.6). It is a reddish-
gray, heart-shaped body, about the size of a pea. Its sensory root is
received from the spheno-palatine branches of the superior maxillary
nerve; its motor root comes from the facial nerve, through the great
petrosal portion of the Vidian nerve, and its sympathetic root through
the sympathetic fibres of the Vidian nerve, derived from the carotid
plexus. The nerves from Meckel’s ganglion are distributed to the orbit,
the palate, the nose, and the pharynx, and are described with the anatomy
of those regions. The Vidian nerve is formed by the great petrosal branch
of the facial nerve (page 69), reinforced by fibres from the carotid sym-
pathetic plexus as it passes forward to the body of the sphenoid bone,
which it enters and traverses through a special canal, the Vidian, to
join the back part of the ganglion of Meckel.

The inferior maxillary nerve is one of the most interesting of the
cranial nerves, from its resemblance to a spinal nerve (page 41). It is the
largest, branch of the great trifacial or fifth cranial nerve (Plate 3, Fig. 2),
and is composed of sensory and motor filaments, owing to the union of the
proper (sensory) portion of the nerve, from the lower angle of the Gas-
serian ganglion, with the distinct motor root of the trifacial nerve, just after
its exit through the foramen ovale. The foramen ovale is five centimetres,
or about two inches, from the outer surface of the head, on a level with the
middle of the zygomatic arch. The inferior maxillary nerve is covered by
the external pterygoid muscle, and is at the outer side of the Eustachian
THE DEEP STRUCTURES OF THE FACE. 143

tube. Almost immediately after the formation of the trunk of the nerve,
as above described, it subdivides into two portions,—the anterior, consisting
mainly of motor fibres, which are distributed to the muscles of mastication
and to the buccinator, and the posterior, consisting chiefly of sensory fibres,
which convey sensation to the teeth and gums of the lower jaw, the skin
about the temple and external ear, and the lower part of the face and
under lip. The motor branches, from the anterior portion, have each been
described with the muscles which they furnish with power. The sensory
auriculo-temporal branch has also been described in detail in its relations
to the parotid gland and its distribution upon the side of the head. Its
peculiar origin, from two roots which surround the middle meningeal artery
and then unite to form a single nerve-trunk, should be remembered. The
other important sensory branches are the inferior dental nerve and the
lingual nerve. The inferior dental nerve leaves the trunk of the inferior
maxillary nerve beneath the external pterygoid muscle, and descends to
the dental foramen, by which it enters the inferior maxillary bone and
accompanies the dental artery in its distribution to the pulps of the lower
teeth (Plate 3, Fig. 2) and the adjoining gums. At the mental foramen
the nerve divides into mental and incisor branches in relation to the
divisions of the mental artery. The mylo-hyoid nerve, which supplies
motion to the mylo-hyoid muscle and the anterior portion of the digastric
muscle, appears to branch off from the inferior dental nerve just as that
nerve is about to enter the dental foramen. This nerve derives its fibres
from the motor root of the trifacial nerve, and is included in the sheath
of the dental nerve for a short distance.

The lingual nerve is at first in close relation with the inferior dental
nerve beneath the external pterygoid muscle, and is very deeply situated
through its entire course. About on a level with the entrance of the
dental nerve into the dental foramen the lingual nerve is joined by the
chorda tympani nerve (page 69), which issues from the canal of Huguier,
close to the Glaserian fissure. The lingual and inferior dental nerves are
frequently connected by a communicating branch underneath the internal
maxillary artery. The lingual nerve descends obliquely from the pterygoid
region to the inner side of the last molar tooth of the lower jaw, being here
144 THE DEEP STRUCTURES OF THE FACE.

placed under the mucous membrane. In this situation it is sometimes
divided to relieve the excruciating pain in cancer of the tongue.

The otic ganglion is an oval, reddish-gray little body situated inter-
nal to the inferior maxillary nerve, just below the foramen ovale. It is
best found by tracing up the highest attachment of the internal pterygoid
muscle until the nerve to that muscle is reached. By following along this
nerve the ganglion will be found about its origin. It is very near the
cartilaginous portion of the Eustachian tube, and the middle meningeal
artery mounts upward behind it. The motor roots of the otic ganglion are
derived from the internal pterygoid nerve, and the sensory root probably
comes from the glosso-pharyngeal nerve; the sympathetic root is derived
from the plexus which surrounds the middle meningeal artery. The
ganglion is brought into relation with the facial nerve by the small
petrosal nerve from the tympanic plexus (page 69). It sends a com-
municating branch to the auriculo-temporal nerve in its distribution to the
parotid gland. It also sends off filaments to the chorda tympani nerve
and to the tensor palati and tensor tympani muscles.

The superior maxillary region consists of the superior maxillary
bones and the muscies, vessels, and nerves which they support. These
have been described with the general anatomy of the face and pterygo-
maxillary region. The superior maxillary bones are peculiarly constructed,
being exceedingly fragile themselves, but very firmly connected by sutures
to the other bones of the face. They are irregular in shape, assist in the
formation of the cavities of the orbits, the nose, and the mouth, and are
hollowed in their central portions, forming the maazillary sinuses, or antra
of Highmore. Each antrum is developed very early in life, but it is not
until the period of second dentition that the cavity assumes its full growth.
Its facial, orbital, and nasal walls are very thin, and often yield to the
pressure of growths or collections of fluid within it. The facial wall upon
its external surface presents the incisive fossa, canine eminence, and canine
fossa (Plate 28), which afford attachment to many of the muscles which
act upon the nose, the upper lip, and the corners of the mouth (Plate 15).
The infra-orbital foramen is above the canine fossa, and transmits the
facial terminations of the superior maxillary nerve and the internal
THE DEEP STRUCTURES OF THE FACE. 145

maxillary artery. The orbital wall or roof of the antrum is grooved upon
the middle of its orbital surface for the lodgement of the above-mentioned
artery and nerve. This groove, two centimetres, or about a finger’s
breadth, from the margin of the orbit, terminates in a canal which soon
subdivides into two branches, one of which, the infra-orbital canal, con-
tinues forward to open on the facial surface below the curved border of
the orbit, giving passage to the infra-orbital vessels and nerves, and the
other, the anterior dental canal, bends downward into the anterior portion
of the antrum, transmitting the anterior dental vessels and nerves to the
front teeth of the upper jaw.

The nasal wall of the antrum is an incomplete partition between the
cavities of the antrum and nose. The further relations of this portion
of the superior maxilla are described with the formation of the nasal
cavities in the region of the nose.

The cavity of the antrum is often crossed by bony shelf-like projections
similar to those found in the cranial sinuses, and on its posterior wall are
the posterior dental canals, which convey the posterior dental vessels and
nerves to the back teeth of the upper jaw (Plate 3, Fig. 2). The floor
of each antrum is formed by the alveolar process, which is the thickest
portion of the superior maxillary bone, is spongy in character, and is ex-
cavated into eight little pits on each side, forming the alveoli, or sockets,
for the corresponding teeth. These alveoli vary in size and depth, that
for the canine tooth being the deepest, while those for the molars
are the broadest. They encroach upon the cavity of the antrum, and
especially the alveoli for the first and second molars, the fangs of
which have sometimes been found to penetrate directly into the antrum,
a fact which has been taken advantage of in the extraction of one of these
molars to drain or explore the antrum. The knowledge of the relations
of the various processes of the upper jaw-bone—z.e., the nasal, malar,
alveolar, and palate processes—is of great value when surgical inter-
ference is required in the many affections to which this bone is liable.
In eacision of this bone it should be understood that its sutural con-
nections with the contiguous bones by these processes are so strong that

they must be severed by the use of the saw or bone-nippers.
19
NO op wp et

PLATE Zi.

Deep dissection of the head and neck on the right side to show the temporal muscle uncovered by its fascia, and the
relative positions of the deep cervical and brachial plexuses of nerves.

. The cut margin of the temporal fascia.

The temporal muscle.

. The ridge for the temporal fascia.

The posterior auricular artery.

. The branches of the occipital artery.

The occipital artery.

. The upper portion of thesterno-mastoid muscle, turned

upward.
The mastoid nerve from the second cervical nerve.

. The external jugular vein, drawn outward.
. The anastomosing branch of the mastoid nerve with

the spinal accessory nerve.

. The second cervical nerve.

. The third cervical nerve.

. The spinal accessory nerve.

. The anterior branch of the third cervical nerve.

. The fourth cervical nerve.

. The trapezius muscle. ;

. The acromial nerve from the fourth cervical nerve.

. The clavicular nerve from the fourth cervical nerve.
. The posterior belly of the omo-hyoid muscle.

. The right clavicle.

. The middle cord of the brachial plexus of nerves.

. The point of entrance of the external jugular vein into

the subclavian vein.

3. The deltoid muscle covered with the deep fascia.
. The compressor naris muscle.

. The lateral nasal artery and vein.

. The facial branches of the facial nerve.

. The superior labial artery.

. The pes anserinus of the facial nerve.

. The orbicularis oris muscle.

. The facial vein.

 

31.
32.
33.
34,
35.
36.
37,
38.
39,

40.
41.
42,
43.
44,

45.
46.
47.
48,

49,

50.
51.
52.
53.

The masseter muscle.

The facial artery.

The depressor labii inferioris muscle.

The inferior labial artery.

The mylo-hyoid muscle.

The anterior belly of the digastric muscle.

The hypoglossal nerve.

Fascia over the submaxillary gland.

The submaxillary vein, joining the facial vein with the
external jugular vein.

The posterior belly of the digastric muscle.

The descendens hypoglossi nerve.

The superior laryngeal nerve.

The pneumogastric nerve.

The point of bifurcation of the common carotid artery
into the external and internal carotid arteries.

The internal jugular vein.

The common carotid artery.

The thyroid notch.

The oblique vein joining the facial vein with the in-
ternal jugular vein.

The communicating branch of the third cervical nerve
with the descendens hypoglossi nerve.

The anterior belly of the omo-hyoid muscle.

The anterior jugular vein.

The sterno-hyoid muscle.

The sterno-thyroid muscle.

54, The left clavicle.
55. The supra-sternal notch.
56, The inter-muscular cleft, between the great pectoral

57.

’ and the deltoid muscles,
. The pectoralis major muscle.
Vi

 

 
THE DEEP STRUCTURES OF THE FACE. 147

The arch of the upper jaw is formed by the union of the alveolar
processes of the two superior maxillary bones, and corresponds to the
horseshoe-shaped arch of the lower jaw, in which the alveolar process
is continuous. The palate process extends inward from the base of the
alveolar process, and forms by its upper surface the anterior part of the
floor of the nasal cavity, and by its lower surface, with that of its opposite
fellow, the roof of the mouth. Posteriorly the palate processes are serrated
for articulation with the horizontal plates of the palate bones. The combi-
nation of these bony processes and plates constitutes the hard palate, which
varies in height and shape in different individuals. The palate process is
much thicker in front than it is behind, and is perforated by foramina
for the passage of the nutrient vessels. The lower surface is concave, and
roughened, presenting little depressions for the palatine glands (Plate 13,
Fig. 4, No. 11), and a bony channel for the passage of the posterior palatine
vessels and the palatine nerves from Meckel’s ganglion. Where the roof of
the mouth is formed by the juxtaposition of the two palate processes, there
is a large opening in the middle line behind the incisor teeth, which is
called the anterior palatine canal. This canal is divided by septa into
four little foramina. Two of these, the anterior and the posterior, are the
foramina of Scarpa, and transmit the left and right naso-palatine nerves
respectively. The others, one on each side, are the foramina of Stenson,
and give passage upward for the terminal branches of the posterior pala-
tine vessels to the nasal cavities from the mouth. On the palatal surface
of many skulls an imperfect suture can be traced arching behind the
anterior palatine canal to the interval between the alveoli for the lateral
incisor and canine teeth on each side. This indicates the original sepa-
ration of the premazilla, or incisive bone, which in some animals exists
permanently. In the human embryo it has a distinct centre of ossific
formation, but generally coalesces at an early date with the rest of the
maxillary bone. When this palatal suture is present it has never been
found accompanied by a sutural line of demarcation on the facial surface
of the normal human bone. That the incisive portion of the jaw has a
distinct origin becomes manifest when an arrest in its development occurs,
occasioning cleft palate. This is sometimes double, the segments con-
148 THE REGION OF THE MOUTH.

taining the incisor teeth on both sides being disconnected from the rest
of the palate by a chasm, and attached above to the vomer only: this
condition is usually associated with double hare-lip.

THE REGION OF THE MOUTH.

The opening of the mouth is bounded by the upper and lower lips,
which are soft and flexible, and consist chiefly of the orbicularis oris muscle
interlacing with fasciculi from the surrounding facial muscles (Plate 15).
The lips are covered outwardly by the skin, which is closely adherent and
very thin at their borders, and inwardly by the loose oral mucous mem-
brane. There is no fat in the extensive connective tissue of the lips, which
allows of considerable swelling when these parts are inflamed; and they
are very mobile, owing to their muscular structure being almost entirely
independent of bony attachment. The lips are joined on each side, form-
ing the angles or corners of the mouth, which are in relation to the first
bicuspid teeth when the mouth is closed. There is great variability in
the length and thickness of the lips, depending upon the peculiarities
of age, sex, and race. The vermilion color of the borders of the lips
is due to the translucent nature of the stratified epithelium with which
they are covered, and through which the vascularity of the subjacent
tissues, due to the numerous papille and capillary plexuses, can be seen.
The lips are endowed with marked sensibility, through the presence of
sensory papille, resembling tactile corpuscles, derived from the ultimate
fibres of the infra-orbital nerves in the upper lip and from the mental
nerves in the lower lip. The coronary arteries (page 124) ramify between
the under surface of the orbicularis muscle and the mucous membrane,
and form a free circular anastomosis around the inside of the lips. They
are of large size, and can be readily felt pulsating on pressing the lips
from within ; and they are apt to be wounded by the teeth in consequence
of a blow upon the mouth. When wounded it is usually found necessary
to tie both ends of the cut vessels. The labial veins form a wide-meshed
plexus in relation to the arteries. Owing to the vascularity of the lips,
nevi frequently occur here; and it is worthy of mention in this connec-
THE REGION OF THE MOUTH. © 149

tion that the lower lip is the most common seat of epithelioma. Embedded
in the meshes of the submucous tissue, within the inner margins of the
lips, there are many racemose mucous glands, the labial glands, which are
arranged in a continuous zone, being most numerous in the centre of the
upper lip. These glands are about the size of small peas, and their ducts
open by small orifices upon the mucous membrane. The closure of the
ducts of these glands produces the mucous cysts often found in this situa-
tion. There are folds of the mucous membrane on the inner side of the
middle of each lip,—the frena labiorwm,—which connect the lips with the
adjacent gums. The lips serve as organs of suction, prehension, and
speech; and, from their varied associations with many of the expres-
sions, they often constitute a characteristic feature. Sometimes a con-
genital fissure exists in the upper lip, from arrest of development: this is
known as simple hare-lip. The space between the closed teeth and: the
inner surface of the lips and adjacent portions of the cheeks is called the
vestibule. The cheeks form the sides of the face externally and of the
mouth internally, and consist of two strata of muscular fibres, with a
variable quantity of fatty tissue interposed. The outer layer of muscular °
tissue is formed by the zygomaticus and platysma muscles, over which the
skin is loosely spread; and the deep muscular layer is the buccinator
muscle, which has a fibrous sheath externally extending to the superior
constrictor muscle of the pharynx and called the bucco-pharyngeal fascia.
On the oral surface of the buccinator the mucous membrane is attached by
a firm submucous connective tissue. The buccal mucous membrane is
continuous with the lining of the cavity of the mouth, but it is thinner
and less sensitive than that of the lips. It contains a number of little
glands,—the buccal glands,—which resemble the labial glands in structure,
but are smaller and are arranged in clusters, especially in relation to
the second superior molar tooth, where the mucous membrane is pierced
by the opening of Stenson’s duct from the parotid gland. These are
called the molar glands, and they are often involved in abscesses, or are
subject to scirrhus-like nodules, in consequence of stoppage of their ducts.
The cheeks are very elastic, and serve to keep the food between the teeth,
mainly through the action of the buccinator muscles. They are also
150 THE REGION OF THE MOUTH.

vascular, both within and without. Within, the vessels in the submucous
tissue form fine vascular plexuses; while without, the vessels are large
and are superficial to the buccinator muscle. In relation to the anterior
border of the coronoid process of the lower jaw, and between it and the
tuberosity of the upper jaw, there is a recess in which a deep-seated
abscess of the temporal region is prone to discharge, owing to the density
of the overlying external fascia. This may be detected by the finger
passed between the teeth and the cheek.

The mucous membrane reflected upon the arching alveolar borders of
the jaws is closely adherent to the periosteum, and forms the gums. It
is peculiarly modified, and contains dense masses of reticulated connective
tissue, which surrounds and sends processes between the necks of the teeth.
The gums are very vascular, and bleed freely upon laceration, furnishing
most of the blood which follows the extraction of a tooth. They have
very little sensibility, except when inflamed, and in health are smooth
and of a pale pink color. They present fine papille around the margins
of the alveoli, which secrete the ¢artar, and their peculiar vascularity
occasions a red line which is often conspicuous in phthisical patients.
In chronic lead-poisoning a blue line appears along their margins, from
a deposition of sulphide of lead, produced by the sulphuretted hydrogen
arising from the decomposition of particles of food retained between the
teeth acting upon the lead circulating in the capillary vessels. The alveoli
are lined with an inflection of the outer epithelial layer of the gums, which
firmly adheres to their periosteal lining membrane.

The gums form a tough protecting covering to the developing teeth
in infancy; and there is always a separation between them until the
further development of the alveolar arches and the eruption of the teeth.

The small size of the facial portion of the skull at birth and during
childhood is due to the rudimentary condition of the jaws and teeth.
The upper and lower maxillary bones commence to ossify at a very early
period, the lower maxillary first. They are developed very slowly, and
undergo various modifications until their complete form is attained at
puberty. There are two sets of teeth, both of which appear at different
periods during childhood,—the first, called the temporary, giving way
THE REGION OF THE MOUTH. 151

to the second, called the permanent. The development of the temporary
teeth in the foetus begins with the first formation of the jaws,—about
the seventh week.

The teeth are calcified papille of the mucous membrane. The stages
of their development have been more carefully studied than perhaps those
of the development of any other portion of the body at this period of
life. Briefly stated, the process may be summed up as follows. The
primitive dental groove is caused by a turning inward or depression of
the oral epithelium, forming a furrow in the edges of the jaws, from
the bottom of which a vascular ridge of papille springs up contem-
poraneously. Each of these papille gradually assumes the shape of
a future tooth, and is covered with a cap of epithelial cells, which
undergo a differentiation so as to form the dentine, the enamel, and the
cement. The changes which take place in the bones of the jaws relate
only to the formation of the sockets of the teeth. At first there is no
appearance of alveoli; but as the changes by which the teeth are developed
occur in the mucous membrane, there is a groove formed in the jaw
itself, which by degrees becomes wider and is divided by thin bony par-
titions. The edges of the alveoli are turned toward one another shortly
after birth, so as to protect the developing temporary teeth from injury.
The germs of the temporary teeth make their appearance from the seventh
to the twelfth week of embryonic life. They are not set vertically opposite
one another in the two dental arches, the upper-jaw teeth being in front
of the lower, a relative position which they maintain, after their eruption,
throughout life. The temporary teeth are very imperfectly developed at
birth, and are not fully formed until about the age of four and a half
years. They number twenty,—four incisors, two canines, and four molars
in each jaw. Their periods of eruption after birth are, approximatively,
the central incisors about the seventh month, the lateral incisors from the
eighth to the tenth month, the anterior molars from the twelfth to the
eighteenth month, the canines from the fourteenth to the twentieth month,
and the posterior molars from the eighteenth to the thirty-sixth month.
The lower teeth generally precede the upper ones.

The permanent teeth consist of two groups,—those which have, and
152 THE REGION OF THE MOUTH.

those which have not, predecessors. To the former group belong the
incisors, canines, and bicuspids; to the latter, the molars. The incisors,
canines, and bicuspids directly succeed to the positions occupied by the
temporary teeth, and correspond in number to them. The molars, three
in number, on both sides of each jaw, are the additional permanent teeth.
The development of the first group of the permanent teeth is effected in a
manner analogous to that of the temporary teeth, a second dental furrow
being formed out of the epithelial lining of the gums and vascular
papille. In the process, the sac which encloses each tooth-germ becomes
attached to the back of the sac of a temporary tooth. The three additional
permanent teeth, the molars, are developed by successive prolongations of
the epithelial tissue toward the angles of the jaws. The calcification
of the permanent teeth extends from birth to about the twelfth year of
life. The fangs, or roots, of the temporary teeth disappear by absorption
as the permanent teeth develop, and the loose crowns gradually become
detached, giving place to the new-comers. The eruption of the permanent
teeth takes place usually as follows: the first molars at six and a half
years, the middle incisors in the seventh year, the lateral incisors in the
eighth year, the first bicuspids in the ninth year, the second bicuspids in
the tenth year, the canines about the twelfth year, the second molars from
the twelfth to the thirteenth year, and the third molars (wisdom teeth)
from the eighteenth to the twenty-first year, or later. It is not practicable
to keep all these facts in mind, but it should be remembered that the first
tooth of the temporary set makes its appearance in the seventh month,
and the first of the permanent set in the seventh year. The lower-jaw
teeth precede the upper-jaw teeth, as in the temporary set. About the
sixth year, before the temporary incisors are shed, the jaws contain all
the temporary and permanent teeth, except the wisdom. During the
growth of the teeth the lower jaw increases in depth and length and
changes its form. At birth this bone consists of two lateral halves united
by fibro-cartilage. The body is a mere shell of bone, and the angle of
the jaw is obtuse. About the first year the two halves become joined
at the symphysis. The jaw becomes gradually elongated’ behind the
mental foramen, so as to accommodate the three extra permanent molars.
THE REGION OF THE MOUTH. 153

The angle also steadily becomes less obtuse until adult age is reached,
when it is nearly a right angle. In old age it becomes again obtuse.
The difference in width between the incisors of the temporary and per-
manent sets is compensated for by the smallness of the bicuspids in
comparison with the temporary molars to which they succeed.

In the adult, the teeth are rarely found in a perfect state, owing to
neglect or abuse. They are symmetrically arranged upon both sides of
the jaws, and are thirty-two in number, eight above and eight below on
each side. The four anterior teeth in each jaw are the incisors, the middle
two of which are called the central and the outer ones on each side the
lateral incisors. Next to the incisors are the canines, one on each side;
behind these are the two bicuspids, or premolars, and last of all the
three molars. Each tooth consists of a free surface, the crown, a body,
a neck, which is embraced by the gum, and one or more roots or fangs,
which are.sunk into the alveoli. The crown of a tooth is covered with
a cap of enamel, which is the hardest known animal substance, and the
fang is covered by a layer of true bone tissue, called cement. The mass
of any tooth is composed of a hard outer substance, dentine, or ivory,
which is harder than bone, and encloses a cavity in which is lodged the
gelatinous mass called the pulp. The pulp is exactly the shape of the
tooth which contains it, and consists of a mass of fusiform cells, called
odontoblasts, surrounded by the minute dental vessels and nerves, which
enter the cavity through canals in the fangs (Plate 3, Fig. 2). .

The incisor teeth are constructed for biting, having a crown shaped
somewhat like a chisel, convex on the outer side and usually concave on
the inner. They have a single, long, conical fang, which is slightly grooved
at the sides. The crowns of the central incisors are three-pointed, until
they are worn away by use, and they are rounded where they join their
fangs. The lower incisors are more slender than the upper ones,—in fact,
they are the smallest of all the teeth,—and their crowns are narrower, with
a straighter cutting edge. The lateral incisors are shaped like the central
incisors, although they are smaller, and in both jaws they correspond
with each other in general character. The edges of the upper incisors

overlap those of the lower in such a way that they are both worn away
20
PLATE 22.

, Figure 1.
Dissection of the back of the neck to show the superficial muscles and the nerves and arteries in the occipital
triangles.
1. The external occipital protuberance. 11. The right occipital artery.
2. The left occipital artery. 12, The right occipitalis major nerve.
3. The left occipitalis major nerve. 13. The right complexus muscle.
4. The left trapezius muscle. 14. The right splenius muscle.
5, The left splenius muscle. 15, The right occipitalis minor nerve.
6. The posterior auricular vein. 16. The right levator anguli scapule muscle.
7. The left sterno-mastoid muscle. 17, The right rhomboideus minor muscle.
8. The left occipitalis minor nerve. 18. The posterior scapular artery.
9. The internal cutaneous branches of the second dorsal | 19. The nerve to the levator scapulz muscle.
spinal nerve. 20. The right rhomboideus major muscle.
10. One of the dorsal cutaneous arteries, from the posterior
branch of the second intercostal artery.
Figure 2.

a

The deep parotid region. The malar bone and the ramus of the lower maxillary bone have been removed to show
the parts beneath, involving the internal maxillary artery (or deep facial artery).

1. The infra-orbital artery.
2. The alveolar artery.

3.
4
5

The inferior dental artery and nerve.

. The facial artery and vein.
. The submaxillary gland (partly dissected to show the

facial vessels).

. The lingual artery and hypoglossal nerve.
. The superior thyroid artery and the superior laryngeal

nerve.

. The deep temporal artery.
. The deep temporal nerve.
10.
11,
12.

The middle meningeal artery.
The parotid gland partially removed.
The origin of the internal maxillary artery.

18.
14,

15.
16.
17.
18.
19.
20.
21.

22,
. The common carotid artery, just below its bifurcation.

The posterior auricular artery.

The lingual branch of the fifth cranial nerve or (gus-
tatory nerve).

The stylo-hyoid muscle.

The posterior portion of the digastric muscle.

The auricularis magnus nerve.

The internal carotid artery.

The external carotid artery.

The internal jugular vein.

The tendon of the digastric muscle in relation to the
hyoid bone, the hypoglossal nerve, and the linguel
artery.

The external jugular vein.
 

 
THE REGION OF THE MOUTH. 155

in a bevelled manner, which does not lessen their cutting power. The
canine teeth are constructed for tearing, having a sharp-pointed crown,
convex in front and slightly hollowed behind. They each have a single
stout fang, which is longer than that of any other tooth, and sometimes
enters the antrum. The lower canine teeth are smaller than the upper,
with blunter points and shorter fangs. The canine teeth overlap each
other so that the upper ones are worn upon their inner surfaces and
the lower ones upon their outer. They become gradually blunted, and
eventually their cutting borders are reduced nearly to the level of the
incisors. The premolars, or bicuspid teeth, are shorter than the canines,
and are provided with two cusps or tubercles on the crown, one of which,
on the cheek side, is marked by a middle ridge. The cusp on the tongue
side of the premolars is highest anteriorly. These teeth usually have
only a single fang.

The molar teeth are the largest in size. Their crowns are rhomboidal
in shape and have from three to five cusps, and each tooth has from two
to four fangs. The cusps on the cheek side are smaller, higher, and
sharper than those on the tongue side. The first upper molar has four
cusps. The first lower molar has five cusps, three outer and two inner,
and has two pulp-canals in its posterior fang. The second upper molar
usually has only three cusps, two outer and one inner. Its outer fangs
are often united. It is very variable. The second lower molar has four
cusps, and has two pulp-canals in its posterior fang. The third upper
molar has three cusps and very irregular club-shaped fangs. The lower
third molar has, in addition to its four cusps, a rudimental cusp posteriorly
on the cheek side.

When the teeth are brought in apposition, the upper teeth overlap the
lower ones in front, while the surfaces of the molar teeth are in contact,
so that the arch formed by the teeth of the upper jaw is slightly larger
at the sides and in front than the arch formed by the teeth of the lower
jaw. The last molars, or wisdom teeth, are the only teeth which are
exactly in contact with one another, all the others having each two antago-
nists. The upper incisors overlap the lower ones and the adjacent sides of
the canines, the bicuspid and molar teeth above and below alternating,
156 THE REGION OF THE MOUTH.

so that each has a bearing on two opposite teeth. By this arrangement,
when one tooth is lost its fellow of the opposite jaw is still useful in
mastication.

The cavity of the mouth (cavum oris) is bounded in front by the
teeth and gums, above by the hard palate, behind by the soft palate and
its arches and the opening into the pharynx, and below by the tongue and
the mylo-hyoid muscles. The walls of the cavity are lined by mucous
membrane, which is continuous with that of the vestibule over the sur-
faces of the gums, and is variously modified in the different localities.
The hard palate is the vaulted roof of the mouth (Plate 12, No. 34,
and Plate 138, Fig. 4, No. 1), formed by the union of the under surfaces
of the palate processes of the superior maxillary bones (page 144). When
the mouth is formed in the feetus there is at first no separation between it
and the nose; but the general cavity is gradually closed by the horizontal
plates of the superior maxillary and palate bones advancing toward each
other and the septum of the nose descending from above to join them in
the middle line. Normally the only trace of the original fissures is the
naso-palatine canal. The closure of the palate begins in front and extends
backward, and is ordinarily accomplished from the eighth to the tenth
week. What is called cleft palate is simply an imperfect closure of the
foetal gap in this region. The cleft is always in the middle line, and
often involves the soft palate and the uvula. If the cleft in the hard
- palate includes the alveolar border, it leaves the middle line and follows
the suture between the maxillary bone proper and the os incisivum. This
defect is usually associated with a corresponding fissure in the upper lip,
called hare-lip, which hardly ever occurs in the middle line, and is always
opposite the interval between the lateral incisor and canine teeth at the
intermaxillary suture. If the cleft in the palate extends on each side
of the os incisivam—separating that bone completely—it is often accom-
panied by fissures on both sides of the upper lip,—doudle hare-lip. The
mucous membrane covering the hard palate is so intimately connected
with the periosteum that the two cannot be separated. In the middle line
the membrane is comparatively thinner than along the borders of the
alveoli, where it is quite thick and contains a compact layer of mucous
THE REGION OF THE MOUTH. 157

glands,—the palatine glands (Plate 13, Fig. 4, No. 11),—the orifices of
which open upon the surface of the membrane and are especially numerous
where the hard and soft palates blend into each other. The density of
the muco-periosteal covering of the palate plays an important réle in the
operation for the remedy of cleft palate. The surface of the palatal mucous
membrane is smooth posteriorly, but raised in transverse ridges anteriorly,
and is divided by a slight raphé, which ends in a little papilla just behind
the interval between the central incisor teeth.

The soft palate (velum pendulum palati) consists of a movable flap
of muscular tissue covered with mucous membrane, which is directly con-
tinuous backward from the hard palate, from which it extends obliquely
downward between the mouth and the posterior nares into the pharynx
(Plate 12). From the middle of the soft palate a free conical process is
suspended, called the wvwla (Plate 13, Figs. 2, 3, and 4), from the sides
of which two folds of mucous membrane, enclosing muscular fibres, arch
outward on each side, connecting the palate with the tongue and the
pharynx. These are the arches or pillars of the palate. The anterior
pillars curve downward and forward to the tongue, while the posterior
pillars curve downward and backward to the pharynx. The posterior
surface of the soft palate is continuous with the floors of the nasal cavities,
and in the act of swallowing it is lifted upward by the levatores palati
muscles into apposition with the back of the pharynx, so as to close the
posterior nares. A raphé exists in the median line of the uvula, prolonged .
from that of the hard palate, which indicates its original formation by
two halves, and is the line of division when the soft palate is affected
with cleft. The uvula varies in length according to the relaxation of
its intrinsic muscles, and occasionally becomes permanently elongated,
causing a tickling sensation in the throat and a distressing cough. The
muscles of the soft palate are immediately under the mucous membrane;
and a proper understanding of their relative position and function is
of the utmost importance in all operations in this region, especially for
the closure of cleft palate, as the action of some of them tends to widen
the cleft, requiring their division before attempting to close it.

The hamular process of the internal pterygoid plate of the sphenoid
158 THE REGION OF THE MOUTH.

bone can be easily detected by the finger pressed upon the soft palate
in close relation to the last upper molar tooth, and is a valuable land-
mark,

The levatores wvule (or azygos) are two little bundles of muscular fibres
which hang side by side, suspended from the posterior nasal spine of the
palate bone and from the palatal aponeurosis, and are covered with a
loose reflection of the mucous membrane, forming the uvula, already
mentioned.

The levatores palati arise from the under surfaces of the apices of the
petrous portions of the temporal bones, and from the adjoining cartila-
ginous portions of the Eustachian tubes. After passing over the superior
constrictor muscles of the pharynx their course is obliquely downward,
and their fibres blend with the levatores uvule on their posterior surface.
Their normal action is to raise the soft palate in deglutition, and they are
powerful retractors of the flaps in cleft-palate operations. In order to
divide either of these muscles, a narrow curved knife should be entered
through the soft structures half-way between the hamular process and
the Eustachian tube and an oblique incision made outwardly.

The tensores palati, or circumflexi, muscles are situated, one on each
side, externally to the levatores palati. They are interposed between
the internal pterygoid muscles and the internal pterygoid plates of the
sphenoid bone, arising mainly from the scaphoid fossee and spines of
that bone. Some of their fibres also come from the contiguous vaginal
processes of the temporal bones and the outer sides of the Eustachian tubes.
From these broad origins the muscles descend on each side perpendicularly
to the hamular processes, where they become somewhat tendinous and are
held in position by bands of connective tissue and lubricated by synovial
bursee. Thence they take an inward direction, and, approaching each other,
their fleshy fibres interlace on the anterior surface of the base of the uvula,
while the tendinous fibres are inserted into the horizontal plates of the
palate bones. The function of these muscles is to render the palate tense,
and they also oppose the closure of a breach extending through it.
Their division may be effected, on either side, by introducing a narrow
knife with the edge upward just along the inner side of the hamular
THE REGION OF THE MOUTH. 159

process and cutting upward a few lines. If the knife in this operation
is pressed against the posterior surface on its withdrawal, the levator
palati may be cut also, but this latter muscle is better cut transversely,
as described before, as its retractive power is greater than that of the
tensor.

The muscles which are contained within the mucous folds of the pillars
of the palate are the palato-glossi anteriorly and the palato-pharyngei
posteriorly. The palato-glossi muscles arise from the anterior surface of
the soft palate, interchanging fibres with each other across the base of
the uvula, and curve downward and forward, to be inserted into the sides
and dorsum of the tongue, blending with the fibres of the stylo-glossi
muscles. The palato-pharyngei muscles each arise from the soft palate
by two fasciculi, which embrace the levatores palati in their relation to the
uvula, and also interchange fibres with each other. Besides these fibres
of origin, a slip from the neighboring Eustachian tube, called the salpingo-
pharyngeus, often joins each muscle. The palato-pharyngei are directed
backward, and, blending with the fibres of the inferior constrictor and stylo-
pharyngei muscles, are inserted into the posterior borders of the thyroid
cartilages. These muscles aid the levatores and tensores palati in drawing
apart the flaps after the operation of staphylorrhaphy, and their division
consists in simply cutting across the posterior pillars, just below the tonsils,
with blunt-pointed scissors.

The principal arteries of the hard and the soft palate are the posterior
palatine branches of the internal maxillary arteries (page 141), which,
after passing down the posterior palatine canals, emerge from the pos-
terior palatine foramina and run along close to the alveolar borders to
the anterior palatine canal (Plate 13, Fig. 4, No. 2). In dissecting off
the muco-periosteal flaps to cover a cleft palate the lateral incisions should
be made as close as possible to the alveoli, in order to preserve these
vessels and secure the vitality of the flaps.

The pillars and back of the soft palate also receive blood on each side
from the ascending pharyngeal artery and from the ascending palatine
branches of the facial artery. The latter vessel is in close relation to the
levator palati muscle, and is the chief source of bleeding after division of
ci

PLATE 28.

Figure 1.

The skin removed from the anterior region of the neck to show the platysma myoides muscle and the superficial

ervical veins. ‘
. The median raphé. 7. A perforating thoracic artery.
. The right thyro-hyoid muscle, seen through the super- 8. The anterior border of the left sterno-mastoid muscle.
ficial fascia. 9. The platysma myoides muscle.
. The anterior border of the right sterno-mastoid muscle. | 10. Superficial transverse veins.
. The right external jugular vein. 11. The left external jugular vein.
. The anterior jugular vein, occupying the middle line, 12, The clavicular nerve.
. The clavicular and acromial nerves. 18, The anterior perforating thoracic artery.
Figure 2.

The anterior cervical muscles, in relation to the veins, arteries, and nerves.

The median raphé has been cut through

and the anterior thyroid muscles separated to display the nerves over the larynx and trachea.

. The right facial artery and vein.
. The anterior portion of the right digastric muscle.
. The facial artery tunnelling the submaxillary gland.

moe

jugular veins.
The thyroid notch.
. The right thyro-hyoid muscle.

SIR or

cation.
8. The right internal jugular vein.

2

beneath the sterno-thyroid muscle.
0. The crico-thyroid artery and vein.

1. The superficial cervical plexus of nerves on the sterno-

mastoid muscle.
2. The transverse cervical nerve.
3. The right external jugular vein.
4. The right omo-hyoid muscle.
5. The right sterno-hyoid muscle.
6. The right sterno-thyroid muscle.
7. The sternal nerve.

clavian vein.

. The oblique vein, connecting the external and internal

. The right common carotid artery, just below its bifur-

. The trunk of the right superior thyroid artery, passing

. The external jugular vein, where it passes into the sub-

 

19.
20.

21,
22.
23.

24.
25.
26.

The sternal end of the right sterno-mastoid muscle.

The supra-sternal notch.

The left facial artery and vein.

The anterior portion of the left digastric muscle.

The left facial artery, coming out of the submaxillary
gland.

. The body of the hyoid bone.

The thyro-hyoid membrane.

. The left omo-hyoid muscle.
27.
28.
29.
30.
31.
82.
33.

The left external carotid artery.

The left internal carotid artery.

The left internal jugular vein.

The position of the cricoid cartilage.

The superficial cervical plexus of nerves.

The left sterno-mastoid muscle.

The descending branches of the superior thyroid
arteries.

. The anterior jugular vein.

. The left sterno-hyoid muscle.

. The left external jugular vein.

. The margin of the left sterno-thyroid muscle.

. The clavicular nerves.

. The sternal end of the left sterno-mastoid muscle.
Von I

 

Plate23
Fie
5

 

 

Copyreht/8.90,by GeoreeMcCewwanMD.

Dissected, Photographed and Colored trom Nature by GEORGE Me. Crectan, MD,
THE REGION OF THE MOUTH. 161

this muscle. The palatine nerves (from Meckel’s ganglion) accompany
the posterior palatine vessels. .

The tensor palati muscle receives a special nerve from the otic ganglion,
which enters the muscle on its posterior surface.

The tongue is the freely movable muscular organ occupying the
cavity of the mouth, designed to assist the various offices of mastication,
deglutition, taste, and speech. When the mouth is closed, the upper sur-
face, or dorsum, of the tongue is convex, conforming somewhat to the palatal
roof, and the point, or éip, lies behind the lower incisor teeth (Plate 12).
The back, or root, of the tongue is attached to the hyoid bone, and it is
supported on each side by a sling of muscles from the styloid process of
the temporal bone and the anterior palatine arches. The under surface of
the organ is connected to the symphysis of the lower jaw. The mucous
membrane covering the upper surface of the tongue is provided with a
thick layer of stratified epithelium, which is being constantly renewed.
The furring or coating of the tongue, as it is commonly called, consists
of detached epithelium commingled with fungi of peculiar and variable
growth, according to the state of the digestive canal. The appearance of
the tongue is an important guide to the physician, and merits very close
scrutiny. The dorsum of the tongue is divided by a raphé into sym-
metrical halves, which end, at the level of the isthmus of the fauces, in a
depression, the foramen cecum, which is the common opening of several
large mucous glands. The posterior third of the upper surface of the
tongue is quite smooth compared to the anterior two-thirds, which are
rough and covered with papille of several distinct kinds. These papille
are supported in a layer of connective tissue, the cortwm, which is thicker
and looser posteriorly than it is anteriorly, where it is very closely adhe-
yent to the muscular tissue. The corium is composed of a dense net-work
of connective and elastic tissue, continuous with the intermuscular septa,
and contains the vessels, nerves, and lymphatics which are associated with
the papillee.

The papille circumvallate (Plate 13, Fig. 4, No. 9) are much the
largest, and vary from eight to twelve in number. They are arranged

upon the back of the tongue in two rows, one upon each side, which
21
162 THE REGION OF THE MOUTH.

converge toward the foramen cecum, resembling in shape the letter V
inverted. Each of these papille is a conical body, inverted, with its apex
resting in a little fossa, and its base presenting on the surface of the tongue
covered with papille, into each of which can be traced with the microscope
filaments from the glosso-pharyngeal nerve and branches from the dorsal
artery of the tongue. The epithelial lining of these papille, as well as of
the walls of the fossee which contain them, encloses numerous flask-shaped
bodies, called taste-buds. The general velvety appearance of the tongue is
due to the numberless filiform papille which are spread over its surface.
These papille consist of conical processes, which terminate in free, hair-
like villi, and are mostly arranged in rows parallel to the circumvallate
papille. The points of the filiform papille are directed backward, so that
they give a rough sensation to the finger if it is passed over the tongue
from behind forward. Scattered over the sides and tip of the tongue,
throughout the filiform papille, are the papille fungiformes (Plate 13,
Fig. 4, No. 10), so called because they resemble little mushrooms. At the
point of the tongue they are most numerous, and are always of a bright
red color. In many of the exanthematous fevers these fungiform papillee
become hypertrophied and their color intensified. The fungiform papillee
contain capillary loops and nerve filaments from the lingual branch of the
inferior maxillary nerve, which terminate in taste-buds. The taste-buds
are composed of a congeries of flattened swpport-cells, which enclose the
so-called gustatory cells.

The mucous membrane on the under surface of the tongue is smooth,
thin, and loose, and presents several distinct folds. In front, in the
middle line, there is a fold reflected from the tongue to the inner surface
of the gum, called the frenwm lingue. Sometimes the frenum is con-
tinued farther forward than usual, or may be abnormally short, producing
the condition known as “tongue-tie,” which is attended by a lisping of the
speech. This can be easily remedied by snipping the free border of the
frenum with blunt-pointed scissors as close to the jaw as possible, so as to
avoid wounding the ranine vessels, which are contained within the elevated
fringes of mucous membrane on the under surface of the tongue, extending
on each side of the frenum toward its tip. The ranine artery lies deeper
THE REGION OF THE MOUTH. 163

than the vein on each side. If the frenum and subjacent muscular fibres
be too freely divided in operating for tongue-tie, there is danger of a child,
in its efforts at sucking, tearing these lax fibres farther open, so that the .
tongue may be forced down upon the epiglottis by the muscles of deglu-
tition and occasion suffocation.

At the sides of the tongue the mucous membrane is reflected to the
body of the lower jaw, and covers over the mylo-hyoid muscles, forming
the floor of the mouth. At the back of the tongue there are folds passing
on each side to the soft palate, which enclose the palato-glossi muscles, and
there are also three folds to the epiglottis, a right and a left glosso-epiglottic
fold and a posterior median, the frenum epiglottidis. The latter serves to
raise the epiglottis when the tongue is protruded (Plate 13, Fig. 4), a fact
which is taken advantage of by drawing out the tongue, so as to open the
pharyngeal air-passages, when a patient under ether breathes stertorously.
The orifices of the submaxillary ducts open upon elevations of the mucous
membrane close to the borders of the frenum lingue; and the orifices
of the sublingual ducts are in the furrows between the sides of the tongue
and the gums. There are a number of mucous glands in the submucous
tissue of the tongue, especially about its root, which resemble the labial
and buccal glands (page 149). Beneath the apex of the tongue, on each
side of the frenum, there is a group of glands which are supposed to be
salivary. There is a considerable amount of connective tissue, as well as
of lymphoid tissue, in the substance of the organ. The latter is found
chiefly at its root. To the presence of these tissues in the otherwise
dense structure are to be attributed the great amount of swelling which
follows inflammation, and the enlargement of the tongue in the affection
known as macroglossia.

The substance of the tongue is composed of intrinsic muscular fibres,
with a small quantity of adipose tissue, arranged in symmetrical halves
which are distinctly separated from each other by a median fibrous septum.
This septum consists of a layer of fibrous tissue extending vertically from
the base to the point, and sometimes contains a plate of fibro-cartilage.
The intrinsic muscles of the tongue are the linguales, which consist of
iwo strata of longitudinal fibres, the superficial and the inferior, the latter
164 THE REGION OF THE MOUTH.

being the larger, extending from the hyoid bone to the tip of the organ,
and having between them an interlacement of transverse and vertical
fibres. The extrinsic muscles of the tongue are those which mainly
produce its numerous and complicated movements. The genro-hyo-glosst
muscles arise from the upper genial tubercles on the inner side of the
symphysis of the jaw, and their fibres radiate in a fan-like manner to
be inserted into the whole of the under surface of the tongue and the
upper part of the body of the hyoid bone. The action of the genio-hyo-
glossi muscles is manifold. Their anterior fibres retract the tongue; their
posterior fibres raise its base and help to protrude the organ. In con-
nection with the linguales they draw down the centre of the tongue from
the tip toward the base, as in sucking. The hyo-glossi are flat quadrilateral
muscles which arise from the body and the cornua of the hyoid bone and
blend with the other muscular fibres on the sides of the tongue. The fibres
from the body pass upward and backward and overlap those from the
greater cornua, which pass obliquely forward. The stylo-glossi arise from
the outer sides of the apices of the styloid processes and from the stylo-
maxillary ligaments, and curve downward to the sides of the tongue, each
dividing into two portions, one of which blends with the lingualis and
the other with the hyo-glossus. The palato-glossi are described with the
soft palate, with which they are more particularly associated.

The sublingual salivary gland (Plate 13, Fig. 2, No. 4) is about
the size and shape of an almond, situated between the mucous membrane
and the mylo-hyoid muscle, its front portion resting in a depression
behind the symphysis of the jaw. It has about a dozen ducts,—the ducts
of Riwinus,—which open upon the floor of the mouth, mostly by inde-
pendent orifices, but one of them terminates in the submaxillary duct,
and is called the duct of Bartholin.

The submaxillary salivary gland (Plate 13, Fig. 2, No. 6, and
Plate 18, No. 20) is very irregular in shape, and about twice the size of
the sublingual gland. It is covered externally by the skin and platysma
muscle (Plate 18), and is in relation to the posterior border of the mylo-
hyoid muscle, generally presenting a submaxillary lobe beneath that
muscle, and a buccal lobe above it, which terminates in the duct of
THE REGION OF THE MOUTH. 165

Wharton, which is five centimetres, or about two inches, in length, and
opens by a narrow orifice at the side of the frenum lingue. The sub-
maxillary gland is placed a little in front of the angle of the jaw, and
upon its back part is tunnelled by the facial artery, which after leaving
it passes up over the body of the jaw in front of the masseter muscle.
Posteriorly the submaxillary and parotid glands are separated by the
stylo-maxillary ligament, although they are often joined together.

The genio-hyoid muscles are very slender fleshy bands which arise
from the inferior genial tubercles back of the symphysis of the jaw
and are inserted into the body of the hyoid bone. They act as elevators
of the hyoid bone. The mylo-hyoid muscle arises mainly from the mylo-
hyoid ridge of the lower jaw, extending from the symphysis to the alveolus
of the last molar tooth, and is attached to the body of the hyoid bone.
It presents a tendinous raphé where the anterior fibres are attached, but
frequently this raphé is absent and the fibres from the mylo-hyoid of
one side become continuous with those of the other and thus establish
a muscular partition or diaphragm to the mouth. This muscle is also
an elevator of the hyoid bone, as in swallowing.

The hyoid bone is a horseshoe-shaped bone, unattached to the general
skeleton, placed above the larynx, and serving to support the numerous
muscles of the tongue. When the head is held erect it may be felt just
below the lower border of the jaw, and four and a half centimetres, or an
inch and three-quarters, behind the chin (Plate 1). It consists of a body
and right and left greater and lesser cornua. The dody is the central por-
tion, has a vertical ridge in the middle anteriorly, and posteriorly has a
smooth concave surface which is in relation to the epiglottis. The greater
cornua extend backward and a little upward to about a line dropped from
the angle of the lower jaw on each side, and have blunt cartilaginous ends.
The lesser cornua on each side are about the size of a grain of corn, and
are connected, by a little joint lined with synovial membrane, to the point
of junction of the body and the greater cornua. The hyoid bone is sus-
pended by the stylo-hyoid hgaments, which extend from the tips of the
styloid processes of the temporal bones to the lesser cornua. The hyoid
bone is an important landmark in the upper part of the neck.
166 : THE REGION OF THE MOUTH.

The tongue is very vascular, receiving most of its blood from a special
artery upon each side, called the dingual, which enters its base and divides
within its substance into numerous branches. These branches anastomose
with one another and with vessels from the facial and ascending pharyn-
geal artery, but there is no communication from side to side, owing to
the median fibrous septum, except perhaps by minute branches at the apex.
The lingual artery arises from the external carotid artery about the level
of the hyoid bone, round the greater cornu of which it curves, after
crossing the superior laryngeal nerve and the middle constrictor muscle
of the pharynx. Thence it passes inward beneath the hyo-glossus muscle
and the hypoglossal nerve, about the point where the intermediate tendon
of the digastric muscle pierces the stylo-hyoid muscle and becomes looped
by a fold of deep fascia to the hyoid bone. At the anterior margin of the
hyo-glossus muscle the artery passes in a very tortuous course along the
under surface of the tongue toward its apex, where it is known as the
ranine artery. The tortuous condition of the lingual artery enables it to
accommodate itself to the elongation and movements of the tongue. In
its course it gives off, near the greater cornu of the hyoid bone, the little
supra-hyoid artery; close to the lesser cornu the dorsal artery, which sup-
plies the mucous membrane at the back of the tongue and the tonsil, and
the soft palate; and, in relation to the genio-hyo-glossus muscle, the swb-
lingual artery, which supplies the sublingual gland.

In consequence of its vascularity, the tongue is often the seat of neevoid
growths, and the operation of excision of the organ for cancer is apt to be
attended with excessive hemorrhage unless the lingual artery is secured
early in the undertaking.

In order to expose the lingual artery for ligation, a curved incision
snould be made over the great cornu of the hyoid bone, about two
centimetres, or a finger’s breadth, from the angle of the jaw, and _ parallel
with it, the head being turned back and to the opposite side. Upon
reaching the tendons of the stylo-hyoid and the posterior portion of the
digastric muscles, a layer of fascia is met with overlying the hypoglossal
nerve, which can be seen through it taking a curved course parallel to the
angle of the jaw. The artery is generally found under the nerve in this
THE REGION OF THE MOUTH. 167

relation, but if it originates higher up, in common with the facial artery
from the external carotid, as it sometimes does, it can be readily found by
drawing outward the submaxillary gland. The lingual veins accompany
the branches of the lingual artery, forming net-works about them, but
instead of emptying into a common trunk they join the superficial and
the deep facial veins. The ranine veins are very large and tortuous, and
are easily noticeable when the tip of the tongue is protruded and turned
upward.

The motor nerve to the tongue is the hypoglossal, which leaves the skull
by the anterior condyloid foramen, and, in close connection with the pneu-
mogastric nerve, passes deeply beneath the internal jugular vein and the
internal carotid artery, until it reaches a point corresponding to the angle
of the jaw, when it comes forward between the vein and the artery,
and, in relation to the posterior portion of the digastric muscle, takes a
curved course over the carotid arteries and the occipital and facial arteries.
As it crosses the occipital artery the branch called the descendens hypo-
glosst is given off, which lies for some distance upon the sheath of the
carotid vessels and is distributed to the depressor muscles of the hyoid
bone (Plate 21, No. 41). The hyo-glossus muscle separates the hypo-
glossal nerve from the lingual artery, along the upper border of the greater
cornu of the hyoid bone. After passing over the hyo-glossus muscle the
hypoglossal nerve communicates with the lingual nerve, and then penetrates
the mylo-hyoid muscle and divides into various branches to supply all the
lingual muscles with motor power. The hypoglossal nerve receives com-
munications from the first two cervical nerves, and is also connected with
the pneumogastric nerve and the superior cervical sympathetic ganglion
at the base of the skull. These communications have important physio-
logical bearings. The tongue receives its sensory and gustatory functions
through the distribution of the lingual and glosso-pharyngeal nerves. The
lingual nerve is a branch of the inferior maxillary nerve, and, descending
between the internal pterygoid muscle and the ramus ‘of the lower jaw
(page 143), curves forward over the superior constrictor muscle of the
pharynx and the upper part of the hyo-glossus muscle. In front of
the latter muscle it is superficial to the duct of the submaxillary gland.
body in position.

SBNOrhWnN Ye

18.

14.
15.

to expose the depth of the trachea at the root of the neck, and its relation to the deep transverse thyroid veins.

PLATE 24.

Figure 1.

The anterior region of the neck. Thesterno-thyroid and sterno-hyoid muscles are removed to show the thyroid

(Same as Plate 23.)

. The right facial artery and vein.

. The right digastric muscle.

. The facial artery passing out of the submaxillary gland.
. The thyroid notch.

. The right thyro-hyoid muscle.

The right internal jugular vein.

. The right superior laryngeal nerve.

. The right superior thyroid artery and vein.

. The right common carotid artery.

. The right sterno-mastoid muscle.

. The right omo-hyoid muscle.

. The branches of the superior thyroid vessels over the

right lobe of the thyroid body.

The anterior jugular vein, at the point where it passes
over the isthmus of the thyroid body.

The right clavicular nerve.

The right external jugular vein.

 

. The left facial artery and vein.

. The left digastric muscle.

. The left submaxillary gland.

. The thyro-hyoid membrane.

. The left internal carotid artery.

. The left external carotid artery.

. The left internal jugular vein.

. The left thyro-hyoid muscle.

. The left superior laryngeal nerve.

. The left superior thyroid artery aud vein.
. The left sterno-mastoid muscle.

. The left omo-hyoid muscle.

. The left external jugular vein.

. The superior thyroid vessels over the left lobe of the

thyroid body.

. The left clavicular nerve.

Figure 2.

The anterior region of the neck. The isthmus of the thyroid body is divided and the two lobes drawn to either side

as Plate 23.)

(ew N

The right facial artery and veins.

The right digastric muscle.

The right facial artery passing out of the submaxillary
gland.

The right hyoid artery.

The body of the hyoid bone.

The thyroid notch.

The right thyro-hyoid muscle.

The right superior laryngeal nerve.

The right superior thyroid artery and veins.

. The right common carotid artery.

. The right internal jugular vein.

. The right omo-hyoid muscle.

. The right sterno-mastoid muscle.

. The right lobe of the thyroid body, drawn aside.
. The superficial cervical veins.

. The right external jugular vein.

. The right inferior thyroid artery and vein.

. The right recurrent laryngeal nerve.

. The transverse thyroid veins in the supra-sternal notch.
. The manubrium sterni.

. The left facial artery and vein.

 

22.
23.
24,
25.
26.
27.
28.
29,
30.

31.
32.
33.

34.
39.
36.
37.
38.
389.
40.

(Same

The left digastric muscle.

The left submaxillary gland.

The left hyoid artery.

The thyro-hyoid membrane.

The left thyro-hyoid muscle,

The left internal carotid artery.

The left superior laryngeal nerve.

The left superior thyroid artery and vein.

The crico-thyroid artery over the crico-thyroid mem-
brane.

The cricoid cartilage.

The left internal jugular vein.

The left omo-hyoid muscle crossing over the common
carotid artery.

The left lobe of the thyroid body, drawn aside.

The left sterno-mastoid muscle.

The left external jugular vein.

The trachea.

The left recurrent laryngeal nerve.

The left clavicular nerve.

The supra-sternal notch.

N. B.—The dissections represented in Plates 23 and 24 were made upon a thick, short-necked, well-developed male
subject, aged thirty-five years, to demonstrate the parts especially concerned in the operations of laryngotomy and
tracheotomy.
late 2A ; 3 ¢ Worrell

 

ted, Photographed and Colored from Nature ty Georce Mc. Cetsan, MD. Copyright /890,by GeoreeMc Ceti anM.D, ; :

 
 
THE REGION OF THE MOUTH. 169

At the under surface of the tongue the lingual nerve divides into
numerous branches (Plate 13, Fig. 2, No. 1), which ultimately are dis-
tributed to the mucous membrane and the fungiform and filiform papillee
on the anterior three-fourths of the dorsum of the organ. It also supplies
the neighboring mucous membrane of the mouth and gums and the lingual
gland, and connects with the terminal branches of the hypoglossal nerve at
the apex of the tongue. In severe neuralgic affections of the tongue
division of this nerve sometimes affords relief. It can readily be reached
by making an incision through the mucous membrane between the vertical
ramus of the jaw and the last molar tooth, or, if the mouth is too small,
by an external incision through the cheek in the line of the oral commis-
sure. In relation to the external pterygoid muscle the lingual nerve is
joined by the chorda tympani from the facial nerve, as already described
(page 143) ; and it sends a few filaments to the submaxillary ganglion near
the posterior border of the mylo-hyoid muscle.

The submaxillary ganglion is not larger than a pin’s head, and is
situated on the hyo-glossus muscle behind the point where the lingual nerve
crosses the submaxillary duct. Its motor root is the chorda tympani; its
sensory roots come from the lingual, and its sympathetic root is formed by
a branch from the sympathetic plexus around the facial artery. The
branches of distribution go to the submaxillary gland, to the floor of the
mouth, and sometimes to the hypoglossal nerve. The glosso-pharyngeal
nerve leaves the skull at the middle of the jugular foramen anterior to
the pneumogastric and spinal accessory nerves, and passes between the
internal jugular vein and the internal carotid artery, crossing the latter
vessel below the styloid process to curve forward over the stylo-pharyngeus
muscle. Here it holds an intermediary position between the lingual and
hypoglossal nerves (Plate 13, Fig. 2, No. 16, and Plate 36, No. 7), and
divides into branches which supply the mucous membrane of the pharynx,
the tonsil, and the back of the tongue. There are two branches of the
glosso-pharyngeal nerve which supply the back portion of the tongue.
One is distributed to the circumvallate papillee and the surface between
them and the epiglottis; the other passes along.the side of the tongue

and joins with the lingual nerve.-
22
170 THE REGION OF THE MOUTH.

The tongue is plentifully supplied with lymphatic vessels, which mostly
accompany the ranine vessels, and, after entering several small lymphatic
glands upon the hyo-glossus muscle, terminate in the deep cervical glands.

The space between the cavity of the mouth and that of the pharynx
is called the fauces, and the narrow part of this space bounded by the
palatine arches constitutes the isthmus fauciwm. Within the triangular
intervals between the anterior and posterior pillars of the palate, on each
side, are situated the tonsils.

The tonsils (amygdale) (Plate 13, Fig. 2, No. 15, Fig. 3, No. 16)
are two oval glandular bodies, composed of an aggregation of lymphatic
follicles, between which small mucous glands open, and are covered on the
external surface by a fibrous sheath and an expansion of the submucous
lining of the pharynx. Normally they should not project beyond the
palato-glossal folds; and their inner surfaces are marked with minute
depressions, which are the orifices leading into the glandular crypts or
follicles. The secretion of the tonsils, in the healthy state, is viscid and
transparent; but it is apt to become white and thick from inflammation,
as in chronic tonsillitis, and to accumulate in the superficial depressions,
appearing like small ulcers or detached pieces of membrane. The tonsils
are variably enlarged in different individuals, and their removal is so
often required that their immediate relations are of great interest. The
enlargement, however, is generally toward the middle of the throat, where
no resistance is offered; and it is for this reason not so easy as it is often
supposed to be to feel an hypertrophied tonsil through the external surface
of the neck, where it is in relation to the angle of the jaw. There are
several lymphatic glands between the tonsils and the greater cornua of the
hyoid bone, which receive the lymphatic vessels from the tonsils: these are
usually enlarged when the tonsils are indurated, and their enlargement
may easily be mistaken for the tonsils themselves. Each tonsil is sepa-
rated by the superior constrictor muscle of the pharynx and its aponeurosis
from the internal carotid artery and the ascending pharyngeal branch of
the external carotid. The latter is very close to the tonsil, but the internal
carotid, except when it is very tortuous, is really out of the way from
danger of being wounded in excision of the tonsil or in the opening of a
THE REGION OF THE MOUTH. 171

tonsillitic abscess. The external carotid artery is not far from the outer
surface of the tonsil, and the facial artery is almost always in close con-
nection with its front border, where it furnishes the tonsillar branch, which
is the vessel most apt to give rise to troublesome hemorrhage. The tonsil
itself is very vascular, as it receives blood from many sources,—the ton-
sillar and palatine branches of the facial,”the descending palatine from
the internal maxillary, the ascending pharyngeal, and the dorsalis lingue
all contributing to it.

The veins from the tonsil form the ¢onsillar plexus on the outer side
of the gland, which empties into the inferior palatine vein and thence into
the deep facial vein. The nerves to the tonsil are derived from Meckel’s
ganglion and from the glosso-pharyngeal nerve. There is a continuous
chain of lymph-follicles extending from one tonsil to the other across the
upper part of the pharynx. The lymphatics arise around the numerous
follicles in the glandular substance and pass into the submaxillary lym-
phatic glands.

The pharynx (Plates 12 and 13) is the passage-way which connects
the cavity of the mouth with the cesophagus. It is eleven centimetres, or
about four and a half inches, in length, and extends from the base of the
skull to the level of the cricoid cartilage. It is lined with a mucous coat
continuous with that of the neighboring passages which open into it, and
its walls consist of muscular fibres arranged in three overlapping planes,
and of a fibrous layer, called the pharyngeal aponeurosis, which is inter-
posed between the muscular and mucous coats. The widest part of the
pharynx is at the level of the greater cornua of the hyoid bone, where it
measures five centimetres, or two inches, across; its narrowest part is at its
junction with the cesophagus, it being here only about nineteen millimetres,
or three-quarters of an inch, in diameter, and it is here, consequently, that
foreign bodies most frequently become lodged. Owing to the yielding
nature of the walls of the pharynx, its cavity is very dilatable. The
submucous tissue of the pharyngeal aponeurosis is much thicker above,
where the muscles are deficient, than it is below, where it gradually
becomes lost as the tube becomes contracted. It is attached to the basilar
process of the occipital bone and to the apices of the petrous portions of
172 THE REGION OF THE MOUTH.

the temporal bones. In the middle the aponeurosis is strongly fixed to
the pharyngeal spine of the occipital bone, and it is continued downward
as the posterior raphé into which the constrictor muscles are inserted. The
superior constrictor muscle is practically a continuation backward of the
buccinator muscle (page 121), being separated from it only by the pterygo-
maxillary ligament. Its fibres are pale in color, and they arise from the
hamular process and the lower part of the internal pterygoid plate of the
sphenoid bone, from the tuberosity of the palate bone, and from the pos-
terior portion of the mylo-hyoid ridge on the lower jaw, to be inserted
mainly into the upper part of the posterior raphé. The upper border of
the superior constrictor is attached by a few fibres to the pharyngeal spine,
and then arches beneath the levator palati muscle and the Eustachian
tube, leaving a semilunar space below the base of the skull, known as
the sinus of Morgagni. The deficiency in muscular fibres in this space
is made up for by a thickening of the aponeurosis in this locality.
The superior constrictor, in addition to the above, also takes origin from
the pterygo-maxillary ligament and from the reflected tendon of the tensor
palati muscle. The lower border is overlapped by the middle constrictor.
The latter muscle arises from the upper border of the greater and lesser
cornua of the hyoid bone and part of the stylo-hyoid ligament. Its fibres
diverge in a radiating manner to their insertion at the median raphé,
where the middle ones interlace with those of the opposite muscle. The
middle constrictor is partially separated from the superior by the stylo-
pharyngeus muscle, a long slender fasciculus which arises from the inner
side of the base of the styloid process and is mainly inserted into the
posterior border of the thyroid cartilage, a few of its fibres blending with
those of the constrictors. The lower border of the middle constrictor is
overlapped by the inferior constrictor. The lingual artery runs forward
between the outer surface of the middle constrictor and the hyo-glossus
muscle. .

The inferior constrictor muscle is the thickest of the three, and arises
from the side of the cricoid cartilage, behind the crico-thyroid muscle,
and from the oblique line on the great wing of the thyroid cartilage and
to its lower cornu. ‘The fibres spread out from their origin and are
THE REGION OF THE MOUTH. 173

inserted into the posterior raphé. The lower fibres blend with the cir-
cular fibres of the cesophagus. Between the middle and inferior constrictor
muscles the superior laryngeal artery and nerve penetrate the thyro-hyoid
membrane to supply the larynx, and beneath the lower border of the
inferior constrictor muscle the recurrent laryngeal nerve enters the larynx.
The action of the constrictor muscles is to compress the pharynx from
above downward. The cavity of the pharynx is divided anteriorly by
the plane of the soft palate into an upper portion, the naso-pharyna,
and a lower, the oro-pharynx. The mucous membrane varies in these
different parts, and is peculiarly adapted to their purposes: the former,
being for the passage of air, is lined with columnar ciliated epithelium
and very delicate, and the latter, for the passage of food, is provided.
with squamous epithelium like the rest of the mouth. Throughout the
whole of the pharynx there are numerous mucous glands whose secretion
keeps the surface lubricated. In the neighborhood of the Eustachian
tubes there are aggregations of these mucous glands and lymphatic
follicles, constituting the so-called pharyngeal tonsils. This area is pecu-
liarly liable to become thickened and swollen in catarrh. The mucous
membrane on each side of the upper part of the pharynx is puckered into
a pouch, called the pharyngeal recess.

The Eustachian tube, which conveys the air to the cavity of the
tympanum (page 65), on each side, opens, by a perpendicular elliptical
slit twelve millimetres, or about half an inch, in length, opposite the
back part of the inferior turbinated bone, in the naso-pharynx (Plate
12, No. 32). The tube has the tensor palati muscle to the outer side and
in front of it, and the levator palati muscle internal and behind it. Its
orifice is usually closed, but during swallowing the tensor palati probably
serves to open it. There is a slight bulging of the mucous membrane
behind the opening of the Eustachian tube, formed by the levator palati.
In relation to the glottis the mucous membrane is gathered into folds,
which allow of the expansion of this part of the pharynx in deglutition.
The mucous membrane of the pharynx is readily inflamed, owing to its
great vascularity, and the inflammatory process is apt to involve the larynx
through contiguity of structure. The pharynx is separated posteriorly
1, The anterior portion of the right digastric muscle. 15.
2. The facial artery and vein, coursing along the front | 16.
border of the masseter muscle. 17.
3. The masseter muscle. 18.
4, The tendon of the digastric muscle, looped down to the 19.
hyoid bone by a band of the deep cervical fascia. 20.

5, A cluster of superficial lymphatic glands.
6. The omo-hyoid muscle, drawn aside. 21.
7, The descendens hypoglossi nerve, over the common 22.
carotid artery. 238,
8. The sterno-mastoid muscle, turned back. 24.
9. The internal jugular vein. 25.
10. The scalenus anticus muscle, separating the subclavian | 26.
artery and vein. 2s
11. The inferior thyroid artery. 28.
12. The common carotid artery. 29,
13. The cords of the brachial plexus of nerves. 30.
14. The subclavian artery. 31.

Figure
Deep dissection of the root of the neck.

1. The facial artery. 17.
2. The posterior portion of the digastric muscle. 18.
3, The external carotid artery. 19.
4, The internal carotid artery. 20.
5. The bifurcation of the common carotid artery. 21,
6. The sterno-mastoid muscle, turned back. 22.
7. The omo-hyoid muscle, drawn aside. 23.
8. The outer cord of the brachial plexus. 24,
9. The middle cord of the brachial plexus. 25.
10. The inner cord of the brachial plexus, 26.
11. The subclavian artery. 27.
12. The clavicle. ‘ 28.
13. The superior thoracic branch of the axillary artery. 29.
14. The anterior portion of the digastric muscle. 30.
15. The body of the hyoid bone. 31.
16. The lingual artery and hypoglossal verve. 382,

PLATE 265.

Figure 1.

Deep dissection of the root of the neck. The thyroid body and omo-hyoid muscle are hooked aside to show the
vessels and nerves, and the clavicle is detached from the sternum.

 

The vagus (or pneumogastric nerve).

The subclavian vein.

The right innominate vein.

The innominate artery.

The subclavius muscie.

The clavicle, detached trom the sternum and pulled
forward.

The anterior portion of the left digastric muscle.

The body of the hyoid bone.

The thyro-hyoid membrane.

The thyroid notch.

The crico-thyroid muscle.

The superior thyroid artery and vein.

The superior laryngeal nerve.

The left sterno-mastoid muscle.

The cricoid cartilage.

The thyroid body.

The isthmus of the thyroid body.

Bi

(Same as Figure 1, the veins being removed.)

 

The thyroid notch.

The crico-thyroid muscle.

The superior thyroid artery.

The superior laryngeal nerve.
The left sterno-mastoid muscle.
The cricoid cartilage.

The common carotid artery.

The left lobe of the thyroid body.
The inferior thyroid artery.

The trachea.

The scalenus anticus muscle,
The pneumogastric nerve,

The innominate artery.

The phrenic nerve.

The manubrium sterni.

The first external intercostal muscle.
Von i
emeoas

Fig 2
Fig |

 

ogred trom Nature tv GeorGce Me. CLei.an MD.
THE REGION OF THE LARYNA. 175

from the prevertebral muscles and their fascia by the loose but strong
post-pharyngeal fascia, which is connected with the sheaths of the carotid
vessels on each side (Plate, 13), and which has an extension outward by
the gap in the deep cervical fascia by which the pharyngeal wall is
brought into relation with the parotid region, as in post-pharyngeal
abscess (page 133). In the connective tissue between the back of the
pharynx and the axis vertebra there is a little lymphatic gland, which
sometimes is the seat of a suppurative collection.

In the areolar layer between the pharyngeal fascia and the constrictor
muscles is the pharyngeal plexus of veins, made up of numerous inter-
communicating veins which branch in all directions and terminate in
the internal jugular veins.

The structures of the pharynx receive their arterial blood by branches
from the ascending palatine and ascending pharyngeal arteries. The
lateral walls of the pharynx are in close proximity, on each side, to the
internal carotid artery and to the pneumogastric, glosso-pharyngeal, and
hypoglossal nerves (Plate 13, Figs. 2 and 3).

The constrictor muscles are all supplied with nerves from the pharyn-
geal plexus of nerves, the inferior constrictor receiving in addition twigs
from the external and recurrent laryngeal nerves. The lymphatic vessels
of the pharynx empty into the deep cervical lymphatic glands, which form
a chain along the sheath of the carotid artery and internal jugular vein.

THE REGION OF THE LARYNX.

At the back of the tongue, and behind the stretch of mucous mem-
brane which contains the chain of follicles extending between the tonsils,
is the pharyngeal opening of the larynx. It is a triangular aperture,
having its base directed toward the tongue, and the cavity of the
larynx into which it leads extends as far as the lower border of the
cricoid cartilage.

The larynx is the commencement of the respiratory passage, and
serves as the organ of the voice, in which are produced the sonorous
vibrations caused by the air coming from the lungs, bronchial tubes,
176 THE REGION OF THE LARYNX.

and trachea. It is triangular and broad above, narrow and cylindrical
below, and flattened behind and at the sides. It consists of a cartilagi-
nous framework, composed of nine separate pieces, which are united
by ligaments and moved by numerous muscles; and its cavity is lined
with mucous membrane continuous with that of the pharynx, mouth, and
nose above, and with that of the trachea below, but peculiarly modi-
fied in this region to subserve the function of phonation. The pharynx,
mouth, and nose form the auxiliary apparatus which modifies the sound
after it passes from the larynx, adapting it to articulation. The thyroid
cartilage is the largest cartilage of the larynx, and consists of two
lateral quadrilateral portions, the ale, which are united anteriorly at
an acute angle, so that they form a vertical median projection. This pro-
jection is called the pomum Adami (Plate 1, and Plate 53, Fig. 1), and is
subcutaneous, being more marked in the male than in the female, and
always serving as an important landmark in the front of the neck. It
is usually separated from the skin by a bursa mucosa; and there is a
median notch at the upper part of the projection, the thyroid notch
(Plates 23, 24, and 25), which allows the cartilage to glide behind the
overlying hyoid bone in the act of swallowing. This is accomplished by
the mode of attachment of the broad, fibro-elastic, thyro-hyoid membrane,
which extends from the upper border of the thyroid cartilage to the
posterior and upper border of the hyoid bone, a little synovial bursa being
interposed between the membrane and the bone. The posterior border of
each ala of the thyroid cartilage is free and prolonged upward into a blunt
cylindrical process, the superior cornu, which is connected to the corre-
sponding greater cornua of the hyoid bone by a posterior thyro-hyoid
ligament, and downward into a shorter process, the inferior cornu, which
curves forward and articulates with the outer side of the cricoid cartilage.
Both the superior and inferior borders of the ale are notched in front of
their respective cornua and present convexly everted lips as they approach
each other at the middle line in front. The inferior border affords attach-
ment to the crico-thyroid membrane which connects the thyroid and cricoid
cartilages. The outer surface of each ala is smooth and marked by a faint
oblique line, which extends from the base of the superior cornu down-
THE REGION OF THE LARYNX. Ltt

ward and forward and gives attachment to the sterno-thyroid and thyro-
hyoid muscles. The inferior constrictor muscle of the pharynx is also
attached to the surface behind the oblique line. The inner surface of
each ala is’ slightly concave, smooth, and covered by mucous membrane.
The thyroid cartilage is so called from its resemblance to a shield, and
because it protects the important structures behind it,

The ecricoid cartilage very closely resembles a signet-ring (hence its
name), and is situated below the thyroid cartilage, with the hoop of the
ring forward and in close contact with the top ring of the trachea. The
posterior, broad, seal-like portion of the cricoid cartilage is two and a
half centimetres, or an inch, in depth, and is received into the interval
between the posterior borders of the ale of the thyroid cartilage. The
narrow hoop-like portion of the cricoid cartilage can readily be felt’ sub-
cutaneously, being prominent in lean and in fat persons at all periods of
life, and is therefore always a reliable landmark in the anterior region
of the neck. The surface of the upper border of the cricoid cartilage is
directed obliquely upward and backward, and gives attachment to the
crico-thyroid membrane, which is thicker in front than at the sides and is
composed mainly of yellow elastic tissue. Outwardly on each side there
is an elevated facet, which articulates with the inferior cornu of the thy-
roid cartilage, and, being provided with a synovial membrane and a cap-
sular ligament, forms a distinct joint which allows of a revolving motion
between the two cartilages. On the upper border of the broad posterior
portion there are also two oval convex surfaces for articulation with the
bases of the arytenoid cartilages, the intervening cavity being occupied by
the arytenoideus proprius muscle. The arytenoid cartilages are so called
because when approximated by the action of the latter muscle they resem-
ble the mouth of a pitcher. They are pyramidal in form, and play an
important part in the mechanism of the. larynx. These cartilages are
symmetrically placed upon the upper and back surface of the cricoid
cartilage, and therefore occupy the upper part of the interval between
the posterior borders of the ale of the thyroid cartilage. Their apices
are directed backward and inward, while their anterior and _ posterior

surfaces are respectively convex and concave. Their inner surfaces are
28
178 THE REGION OF THE LARYNX.

nearly flat, and face each other, being covered by the lining mucous
membrane. The posterior surfaces afford attachment to the arytenoideus.
muscle. The anterior surfaces are irregular, and afford attachment to the
thyro-aryteenoideus muscle on each side and to the fold of mucous mem-
brane called the upper or false vocal cord. Where the anterior surface
rests upon the cricoid cartilage there is a pointed angle (the vocal process),
to which is attached the true vocal cord. Each apex is surmounted by a
nodule, the corniculum laryngis (of Santorini), which serves to continue
the arytenoid cartilage upward and inward.

The epiglottis is a thin, oval, leaf-shaped plate of fibro-cartilage, the
free rounded margin of which can usually be seen through the mouth when
the tongue is protruded (Plate 13, Fig. 4, No. 17), and serves as a trap-
door to close the glottis against the intrusion of food in deglutition. Its
lower end is long and narrow, and connected by the thyro-epiglottic liga-
ment to the angle of the thyroid cartilage just below the median notch
between the two ale and above the vocal cords. A fibrous connection also
exists between it and the posterior surface of the hyoid bone,—the hyo-
epiglottic igament. ‘The mucous membrane is extended from the base and
sides of the tongue upon the anterior surface of the epiglottis in three folds,
constituting the median, right, and left glosso-epiglottic ligaments. The
posterior surface is covered with a number of little mucous-glands lodged
in depressions, and its mucous membrane is reflected upon each side, in
loose folds, to the arytenoid cartilage, forming the aryteno-epiglottic folds.
The function of the mucous glands is to keep the adjoining parts moist:
they are peculiarly apt to become inflamed in those who speak much in
public, and are the seat of “clergyman’s sore throat.” The laxity of the
aryteno-epiglottic folds is due to the quantity of areolar tissue in their
locality, which allows of considerable swelling in acute laryngitis, and
becomes the seat of the dangerous condition known as “cedema of the
glottis.” Foreign bodies of considerable size also often become retained
for long periods of time within these folds of the mucous membrane.
Within the aryteno-epiglottic folds there are small whitish nodules of
cartilage, one on each side, in immediate relation to the apex of the
arytenoid cartilage, and known as the cuneiform (or Wrisberg’s) cartilages.
THE REGION OF THE LARYNX. 179

Occasionally there are found minute accessory cartilaginous ‘plates situated
near the anterior borders of the vocal cords in the female larynx, to
which has been attributed the power of the singing voice in the so-
called. “head-notes” (Seiler). The principal cartilages of the larynx, the
thyroid, the cricoid, and the arytenoid, are of the hyaline variety, and
have a tendency to ossify in old age; but the epiglottis, the cornicula, and
the cuneiform cartilages do not change, being composed of yellow fibro-
elastic tissue. Between the cartilaginous framework and the mucous lining
there is a layer of elastic connective tissue, called the laryngeal fascia.

To one looking down into the cavity of the larynx the mucous mem-
brane presents, in the middle line, below the epiglottis, an elevation known
as the cushion, or pulvinar, of the epiglottis, from which a crescentic fold
arches downward on each side enclosing some fatty tissue and lgamentous
fibres, the superior thyro-arytenoid ligaments, or false vocal cords. Below
these there is another pair of more prominent folds, which extend on
each side from the anterior angles of the bases of the arytenoid carti-
lages to the sides of the middle thyroid fossa. These are composed of
fibro-elastic tissue, the wferior thyro-arytenoid ligaments, or true vocal
cords, and are covered with a very thin and closely-adherent layer of
mucous membrane, through which their free inner margins appear as
white glistening bands. The spaces between these upper and lower pro-
jections on each side are called the ventricles of the laryna, which are
recesses opening into a small pouch, the sacculus laryngis (of Morgagni),
and allow freedom to the vibrations of the true vocal cords. Each sacculus
ascends between the upper fold and false vocal cord and the inner surface
of the thyroid cartilage nearly to its upper border and at the side of the
epiglottis. It contains a number of follicular glands, whose secretion
lubricates the true vocal cords through the action of» the so-called com-
pressor sacculi laryngis muscle. The strength and/ depth of sound are
probably due to the development of the ventricles.!

The opening in the cavity of the larynx between the inferior or true
vocal cords is the glottis. It is of triangular form, with the apex forward
when the parts are at rest, but varies in shape, and becomes contracted
or dilated, according as the vocal cords are rendered tense or relaxed by
180 THE REGION OF THE LARYNX.

muscular action. The glottis begins in a point at the back of the thyroid
cartilage, and is bounded on each side by the inner edges of the true
vocal cords and by the interval between the arytenoid cartilages. It is
limited behind by the mucous membrane reflected over the arytnoideus
muscle. The anterior portion of the opening, between the vocal cords, is
called the vocal area, and the posterior portion, between the arytenoid
cartilages, the respiratory area. The length of the glottis varies in the
male and the female, being, after puberty, in the former a little less
than two and a half centimetres, or an inch, and in the latter about two
centimetres, or three-quarters of an inch. The width depends upon the
degree of dilatation or contraction of the vocal cords. When they are
at rest the widest part does not exceed four or five lines in the male and
two or three lines in the female: hence the name rima glottidis, or chink”
of the glottis. In speaking or singing the glottis is narrowed and the
vocal cords are nearly parallel. Below the true vocal cords the cavity of
the larynx widens, becoming nearly circular at the lower margin of the
cricoid cartilage. The vocal cords measure in the adult’ male a little over
twelve millimetres, or half an inch, and in the female a little less. At
puberty they undergo marked modification with the development of the
rest of the vocal apparatus.

The intrinsic muscles, which act upon the larynx and are especially
concerned in producing changes in the vocal cords by which they modify
the voice, are arranged in four pairs,—the crico-thyroid, the thyro-
arytenoid, the posterior and lateral crico-arytenoid, on ‘each side, and a
single one in the middle, the arytenoideus proprius muscle. The crico-
thyroid muscles (Plates 23, 24, and 25) arise from the front and sides of
the cricoid cartilage and pass obliquely to be inserted into the inferior
border and cornu of the thyroid cartilage on each side. Acting from
above, these muscles raise the hoop of the cricoid cartilage, and thereby
depress the arytenoid cartilages so as to stretch and render tense the true
vocal cords, the thyroid cartilage being at the same time fixed by the
extrinsic thyro-hyoid muscles (page 236).

The crico-thyroid muscles receive their motor influence from the
external branch of the superior laryngeal nerve, being the only muscles
THE REGION OF THE LARYNX. 181

of the larynx supplied by that nerve, while the rest of its branches, being
sensory, are distributed to the mucous lining membrane of the organ.
There are connecting filaments, however, between the superior laryngeal
nerve and the inferior or recurrent laryngeal nerve, which furnishes all
the other intrinsic laryngeal muscles with motion.

The thyro-arytenoid muscles each consist of two flat overlapping por-
tions. The owfer portions arise from the thyroid ale and the contiguous
portion of the crico-thyroid membrane, and pass backward to be inserted
by some transverse fibres into the arytenoid cartilages, and by some
oblique fibres into the aryteno-epiglottic folds, a few of the latter fibres
passing to the epiglottis on each side and being therefore sometimes called
the thyro-epiglottic muscles. The imner portions arise from the anterior
attachment of the true vocal cords and the adjacent fossa of the thyroid
cartilage, and, passing backward, are inserted into the anterior angles of
the bases of the arytenoid cartilages. Their fibres run parallel with the
true vocal cords, many of them blending with the thyro-arytenoid liga-
ments in their substance, the vocal fibres and others radiating beneath the
mucous membrane over the ventricles of the larynx. Owing to the
diversity of origin of their fibres, the thyro-arytenoid muscles are very
complicated in their action. Their main use is to draw forward the
arytenoid cartilages and thus to relax the vocal cords; but, owing to
the connection of their inner portions with the cords, the degree of
tension of the latter is supposed to be modified by the independent action
of the vocal fibres of the muscles. The successive action of the various
fibres in unison on both sides produces a rotation of the arytenoid carti-
lages inward, so that the rima glottidis is narrowed and the vocal cords
are approximated, assuming the position necessary for phonation.

The posterior crico-arytenoid muscles arise from the flattened surfaces
on the cricoid cartilage on each side of the posterior median ridge. Their
fibres are also arranged in segments, most of them converging to the
outer angles of the bases of the arytenoid cartilages, but some of the
lowest fibres often pass to be inserted into the inferior cornua of the
thyroid cartilage. The action of these muscles is brought into play at
each inspiration during life, and serves to rotate the arytenoid cartilages
PLATE 26.
Figure lI.

The sternum and costal cartilages removed to show the anterior mediastinum, and particularly the relations of the

pleure to the pericardium.

 

 

1. The right pneumogastric nerve. 11. The left pneumogastric nerve.
2. The right recurrent laryngeal nerve. 12. The left scalenus anticus muscle.
8. The innominate artery. 18. The left subclavian artery.
4, The right innominate vein. 14, The left subclavian vein.
5. The superior vena cava. 15, The left innominate vein.
6. The costal surface of the right pleural sac. 16. The left pleural sac.
7. The sternal end of the right fifth rib. 17. The pericardium over the great vessels at the base of
8. The right pleural sinus overlapping the pericardium. the heart. :
9, The sternal end of the right sixth rib. 18. The pericardium over the right ventricle of the heart.
10. The upper surface of. the diaphragm. 19, The sternal end of the left fifth rib.
Figure 2.
Dissection of the vascular system of the foetus (at five months and a half).
N.B.—The injection was introduced by the umbilical vein, and the photograph represents the actual size.
1, The right common carotid artery, pneumogastric | 12, The arch of the aorta, showing the origin of the great
nerve, and jugular vein. arteries.
2. The innominate artery. 13. The ductus arteriosus.
3, The entrance of the superior vena cava into the right | 14. The left branch of the pulmonary artery.
auricle of the heart. 1d. The pulmonary artery.
4, The right lung in the back wall of the thoracic cavity. 16. The left lung in the back of the thoracic cavity.
5. The ductus venosus passing into the inferior vena | 17. The heart, with the right and left coronary vessels.
cava. 18. The diaphragm.
6. The inferior vena cava. 19, The abdominal aorta.
7. The hepatic veins. 20. The left kidney.
8. The portal vein. 21. The left renal vein.
9, The umbilical vein. 22. The right hypogastric artery.
10, The umbilical cord. 23. The bladder.
11, The left common carotid artery and jugular vein. 24. The left hypogastric artery.

Figure 3.

Dissection of a child, three weeks after birth, showing especially the relations of the thymus gland and the supra-

renal capsules.

1. The crico-thyroid arteries. 11. The right kidney.
2. The cricoid cartilage. 12. The inferior vena cava.
3. The thyroid body. 13, The left common carotid artery and jugular vein.
4, The right internal mammary artery and veins on the 14. The left internal mammary vessels on the inner surface
inner surface of the wall of the thorax, which is of the thoracic wall, reflected outward,
reflected outward. 15. The pulmonary artery.
5. The right innominate vein. 16. The left lung.
6, The thymus gland overlying the arch of the aorta and 17. The right ventricle of the heart,
the left innominate vein. | 18. The left supra-renal capsule.
7. The right lung. 19. The abdominal aorta.
8. The right auricle of the heart. 20. The hilum of the left kidney.
9, The right supra-renal capsule. 21. The branches of the superior mesenteric artery.
10, The right renal vein. ;
Figure 4.

Photograph of a preparation (in the author’s cabinet), showing a remarkable disposition of the heart and inde-
pendent origins of all of the great vessels from the root of the aorta.

N. B.—This specimen was removed from the body of a young man, aged twenty-seven years, who died from phthisis.
There is no arch to the aorta, and the position of the heart, when discovered, was vertical within the thorax, as shown
in the figure. There is only one auricle and one ventricle. No other abnormality of the arteries was found in the body.

. The right external carotid artery.

. The right internal carotid artery.

. The right superior thyroid artery.

. The right common carotid artery.

. The right thyroid axis.

. The independent origin of the right subclavian artery.

. The left external carotid artery, branching into the
lingual, facial, and temporal arteries.

. The left internal carotid artery.

NJoorwnwnr

ao

9.
10.
11.
12,

The left superior thyroid artery.

The left common carotid artery.

The left vertebral artery.

The left transversalis colli and supra-scapular arteries.
. The left subclavian artery.

. The independent origin of the left subclavian artery.

. The auricle of the heart.

. The ventricle of the heart.

. The descending aorta.
       

( nh Copyright (89) by GeoreeMe Leta MD.
Dissacted, Photographed and Colored’ tram Nature by Georce Mc. CLectan, M D, Myaerpan

 
THE REGION OF THE LARYNX. 183

by drawing their outer angles toward the middle line, and consequently
their anterior angles, to which the vocal cords are attached, from the
middle line, so that the rima glottidis is dilated. The lateral crico-
arytenoid muscles are much smaller than the posterior. They can be seen
only by removing the ale of the thyroid cartilage. They arise from
the sides of the upper border of the cricoid cartilage, and are inserted
by their converging fibres into the outer angles of the bases of the
arytenoid cartilages in front of the posterior crico-arytenoid muscles. They
serve to draw the arytenoid cartilages inward and forward, and thus to
approximate and relax the vocal cords. The single arytenoid muscle is
attached to the posterior surfaces of the arytenoid cartilages, and mainly
consists of transverse fascicles, which serve to draw them together and
thus cause the contraction of the rima glottidis. There are other mus-
cular fibres, intimately connected with the former, which arise from the
outer angles of the arytenoid cartilages and ascend obliquely from side
to side, so that they cross one another, some to be attached to the apices
of the opposite arytenoid cartilages, while others are continued within the
aryteno-epiglottic folds to the sides of the epiglottis and are therefore
sometimes called the aryteno-epiglottic muscles. ‘The lower fasciculi of
the latter constitute the compressor sacculi muscles (of Hilton), already
‘referred to. Throughout the folds of the mucous membrane in relation
to the epiglottis there are other bundles of muscular fibres, sometimes
more developed than at other times, the functions of which have given
rise to much speculation; but they are of little comparative importance,
having probably nothing to do with the modification of the voice, but
rather assisting the constricting influences upon the epiglottis in swallowing.
At puberty these muscles are not so rapidly developed as the cartilages,
and it is owing to this that the so-called “change of voice” occurs.
These muscles become stronger with practice, according to the efforts
of singers and speakers.

The extrinsic muscles of the larynx are those which are attached to
the hyoid bone and thyroid cartilage, which they serve to fix so that the
intrinsic muscles can act. They are described with the anterior region

of the neck.
184 THE REGION OF THE LARYNX.

The arteries of the laryna are derived from ‘the superior or descending
thyroid branch of the external carotid artery and the inferior or ascending
thyroid branch from the thyroid axis of the subclavian artery. The
superior thyroid furnishes most of the blood-supply to the larynx by
means of the superior laryngeal artery, which runs inward beneath the
extrinsic laryngeal muscles, and, after passing between the middle and
inferior pharyngeal constrictor muscles (page 173), penetrates the thyro-
hyoid membrane and sends branches to the intrinsic muscles and mucous
membrane. Sometimes this vessel perforates the ala of the thyroid carti-
lage. Its radicles anastomose freely with those of its fellow and with those
from the inferior thyroid arteries, so that the mucous membrane is very
vascular, as is demonstrated by the rapid engorgement and change from the
ordinary pink color to a bright red in consequence of the slightest irrita-
tion. The external continuation of the superior laryngeal artery descends
to the inferior border of the thyroid cartilage, close to which it courses
over the crico-thyroid membrane and is here called the crico-thyroid artery
(Plates 20, 23, 24, and 25). This vessel forms a little communicating loop
with its fellow from the opposite side, which ordinarily is very insignifi-
cant, and, as the loop itself is nearer to the thyroid cartilage than the
cricoid, it can be avoided in an emergency operation for laryngotomy by
introducing the knife with the blade parallel to and just above the upper
border of the cricoid cartilage and then turning the cutting edge down-
ward toward the middle line. Occasionally, however, the crico-thyroid
artery is quite large (Plate 24, Fig. 2, No. 30), or there may be present an
anomalous branch from the superior thyroid artery (Plate 25), occupying
its position: so that, if time permits, it is safer not to open the larynx with-
out making a preliminary cutaneous incision and exposing the crico-thyroid
membrane for examination. In children the crico-thyroid space is very
small, and the hoop of the cricoid cartilage must be cut through if it is
desired to insert a canula. The mucous lining at the top of the trachea
is so loose that a canula may be introduced between it and the membrane
instead of entering the trachea. This in fact has happened at the hands
of skilful operators. The veins of the larynx accompany the arteries, and
terminate in the superior, middle, and inferior thyroid veins.
THE REGION OF THE LARYNX. 185

The nerves of the larynx are the branches of the superior or descending
and inferior (recurrent) or ascending laryngeal branches of the pneumogas-
tric nerve. The superior laryngeal nerve arises from the inferior ganglion
of the pneumogastric nerve, descends by the side of the pharynx between
the middle and inferior constrictor muscles, in close company with the
superior laryngeal artery, and divides into the internal and external
laryngeal nerves. The internal laryngeal nerve penetrates the thyro-
hyoid membrane, with the internal branch of the artery, and endows
the mucous membrane throughout the larynx with sensibility, which is
normally very acute in the folds about the epiglottis, so that the entrance
of the air-passage is guarded against the danger of food passing the wrong
way in the act of deglutition. Whenever a foreign body, such as a crumb
or a fish-bone, touches the mucous membrane of the larynx, it induces a
spasmodic cough and an involuntary attempt to expel it. The sensibility
of the lining mucous membrane is, however, variable, and it is remarkable
that when foreign bodies are retained within its folds their presence is
not only tolerated, but the patient in a little while becomes unconscious
of them. It is owing to this fact that the modern method of “intubation”
for the relief of stenosis of the larynx is at all feasible. It is probable,
too, that the usual sensibility of the mucous membrane is diminished
when the parts are cedematous from inflammation. The branches of the
internal laryngeal nerve form plexuses beneath the epithelial layer of
the mucous membrane, terminate either in end-bulbs or bodies resembling
the taste-buds of the tongue, and are surrounded with ganglionic cells.
There are fewer of these in relation to the true vocal cords than elsewhere
in the larynx. This nerve is connected with the inferior laryngeal nerve
by a filament which passes downward behind the ala of the thyroid
cartilage, and another filament usually pierces the arytenoideus muscle,
probably supplying it. The external laryngeal nerve, after descending
beneath the depressor muscles of the larynx, supplies mainly the crico-
thyroid muscle. It furnishes a twig also to the adjacent lobe of the
thyroid body.

The inferior (or recurrent) laryngeal nerves arise from the pneumo-

gastric nerves at the root of the neck (Plates 32, 33, 35, and 40), but
24
186 THE REGION OF THE LARYNY.

differ in their relations upon the two sides. The right inferior laryngeal
nerve leaves the pneumogastric at the lower border of the subclavian
artery, near its origin from the innominate artery, and takes an oblique
course upward under the subclavian and inferior thyroid arteries to the
side of the trachea. The deft inferior laryngeal nerve leaves the pneumo-
gastric at the lower border of the arch of the aorta, about the commence-
ment of its descending portion, and winds upward under it toward the
trachea. On both sides the nerves occupy the groove between the trachea
and the cesophagus (Plate 24, Fig. 2), and enter the larynx beneath the
inferior constrictor muscle, sending branches to all the intrinsic laryngeal
muscles except the crico-thyroid, as already stated (page 180).

The recurrent course of the inferior laryngeal nerves has attracted
the attention of anatomists from the time of Galen, and many different
explanations for it have been offered. It is probably due to the variations
that take place commensurate with the developmental changes in the
branchial apparatus of the embryo in this region, and the normal courses
of these nerves, upon the right and left sides, as above given, are con-
sequent upon the relations of the great arteries at the root of the neck.
It has been observed that when these arteries vary in their origin, especially
the right subclavian, the right inferior laryngeal nerve is not recurrent,
but leaves the right pneumogastric opposite the cricoid cartilage.

The lymphatic vessels of the laryna accompany the veins and end in
the deep cervical lymphatic glands about the lateral lobes of the thyroid
body.

Being situated between the trachea and the hyoid bone, which sup-
ports the tongue, the larynx is consequently subordinated to the move-
ments of that organ. The mobility of the larynx is necessary for the
acts of swallowing and speaking. During the latter act the larynx is
raised in the emission of high sounds and lowered in that of deep sounds.
During swallowing, the larynx is raised upward and forward. In moving
forward it opens the orifice of the gullet so that it can receive the bolus
of food, and in moving upward it meets the base of the tongue, which
closes the epiglottis over the glottis so that particles of the food cannot
enter the respiratory apparatus. The mobility of the larynx renders
THE REGION OF THE NECK. 187

operations on the organ very difficult, and it is essential in all such
that the organ should be first steadied as much as possible.

The trachea is described with the anterior region of the neck
(page 236).

THE REGION OF THE NECK.

The skeleton of the neck (Plates 1 and 28) is so well covered by the
surrounding soft structures (Plates 12 and 14) that its prominences are
less conspicuous to external observation than those of any other region
of the body. The relations of the component parts of the neck are con-
siderably influenced by the position of the cranium, which is supported,
somewhat behind its axis, upon the most flexible portion of the vertebral
column. It should be remembered that a line drawn from side to side
in front of the mastoid processes will bisect the condyloid processes, and
that the upper-jaw teeth are on a line with the foramen magnum at the
base of the skull. If a horizontal section of the neck is made about the
level of the fifth cervical vertebra (Plate 14, Fig. 1, No. 1), the segment
of the body of that vertebra will be found in the anterior part of the
section, together with the gullet, windpipe, great vessels, nerves, and glands,
while the muscles which hold the head erect upon the spine will occupy
principally the posterior part.

The bony landmarks of the neck are very few, but they are very
important. They can be ascertained by pressure or manipulation, and
by changing the relative positions of the head and trunk.

When the body is upright, with the shoulders squared and the head
held so that the face looks straight forward, a line drawn obliquely from
the occipital protuberance along the body of the lower jaw to the chin
is about parallel with a line drawn from the lower border of the first dorsal
vertebra to the top of the sternum; and these two lines may be considered
as the upper and lower limits of this region. The atlas vertebra cannot
be felt at the back of the neck through the external parts, but by bending
the head forward or backward the spinous processes from the second
to the seventh cervical vertebra can be readily detected. The seventh
vertebra is always so well marked (Plate 1, No. 15) that it has received
SM Sop epe

ia

10.
11.

12,
13.

14.
15.
16.
17.

18.
19.
20.

21.
22.

23.
24.
. The greater trochanter of the femur.
26.
27.
28.

29.
30.
31.

PLATE 27.

A topographical survey of the anterior surface of the body of a well-developed adult male, with especial reference
to the clinical study of the relations of the thoracic and abdominal viscera. Also showing the relations of the bones to
the surface of the right upper extremity, and the localization of the areas of distribution of the sensory nerves on the
anterior surface of the left arm and forearm. ,

The apex of the right lung above the clavicle.

The position of the innominate artery.

The position of the greater tuberosity of the humerus.

The position of the head of the right humerus,

The position of the lesser tuberosity of the humerus.

The approximation of the lungs over the root of the
heart, in full inspiration.

. The junction of the right third costal cartilage with the

sternum, corresponding to the position of the base
of the heart.

The position of the aortic semilunar valves.

The ppsition of the right ayriculo-ventricular valve.

The right nipple.

The position of the upper surface of the liver in rela-
tion to the right arch of the diaphragm.

The position of the lesser curvature of the stomach.

The extent to which the lower lobe of the right lung
descends in full inspiration, parallel with the lower
border of the cartilage of the sixth rib.

The cartilage of the right seventh rib.

The position of the right lobe of the.liver.

The internal condyle of the right humerus.

The position of the fundus of the gall-bladder, in rela-
tion to the right eighth costal cartilage.

The position of the head of the radius.

The position of the lower portion of the right kidney.

The position of the lower portion of the inferior vena
cava. .

The superior anterior spine of the right ilium.

The position of the cecum and the vermiform appen-
dix.

The position of Poupart’s ligament.

The head of the right femur.

The lesser trochanter of the femur.

The apex of the left lung above the clavicle.

The cutaneous area of the distribution of the external
' supra-clavicular nerve.

The supra-sternal notch.

The position of the left common carotid artery.

The position of the left subclavian artery.

 

82.

33.
34,
35.
36.
37.
38.
39,

40.
4.

43.

as

The ridge between the manubrium and the gladiolus
of the sternum.

The position of the pulmonary artery.

The position of the semilunar valves of the pulmonary
artery.

The position of the left auriculo-ventricular valve.

The area of the distribution of the lesser cutaneous
nerve.

The cutaneous area of the distribution of the circum-
flex nerve.

The left nipple.

The junction of the left fifth rib with its cartilage.

The normal{position of the apex beat of the heart.

The cutaneous area of the distribution of the intercosto-
humeral nerve.

. The tip of the ensiform cartilage.

The extent to which the lower lobe of the left lung
descends in full inspiration.

. The cartilage of the left seventh rib.
. The cutaneous area of the distribution of the internal

cutaneous nerve.

46. ‘The position of the spleen in relation to the left eighth,

47.

a

48.

50.

51.
52.

58.
54.
55.
56.

57.
58.

ninth, and tenth ribs.

The position of the stomach in relation to the antcrior
wall of the abdomen.

The cartilage of the left ninth rib.

. The position of the lower portion of the left kidney.

The position of the abdominal aorta in relation to the
body of the second lumbar vertebra.

The umbilicus. ui

The cutaneous distribution of the musculo-cutaneous
nerve on the anterior surface of the forearm.

The lower part of the cutaneous area of the distribu-
tion of the musculo-spiral nerve.

The position of the sigmoid flexure of the colon.

The position of the internal abdominal opening.

The lower part of the cutaneous area of the distribu-
tion of the musculo-cutaneous nerve.

The position of the external abdominal opening.

The upper part of the cutaneous area of the distribu-
tion of the radial nerve.
late 27 Von I

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Copynght/89/by GeorseMc Cretan MD

hotagraphed and Desiened from Nature by GEORGE Mc.CLELLAN M.D
2; Armstrong & Co Lith Boston
THE REGION OF THE NECK. 189

the special designation of the vertebra prominens. Owing to the obliquity
of the spinous process of the fifth vertebra, it is on a level with the disk
between the bodies of the fifth and sixth. On the sides the transverse
process of the atlas vertebra can, be felt in front of and below the mastoid
process, and by deep pressure in the supra-clavicular fossa the transverse
process of the seventh vertebra can be distinguished. About a finger’s
breadth above the latter, the head being moved from side to side, the
anterior tubercle of the sixth vertebra is perceptible to the touch, which,
because of its relation to the overlying carotid artery, is known as the
“carotid tubercle.”

In the front of the neck the hyoid bone and the external cartilages
of the larynx, the thyroid and ericoid, offer reliable indications to the posi-
tion of the deep vessels and adjoining parts; but, owing to the mobility of
these structures, which permits of their accommodation to the efforts of
swallowing and of forced respiration, and to the changes of position in con-
sequence of the flexibility of the cervical vertebre, their relation to the
chin above and to the top of the sternum below should be carefully noted.
In the adult, when the head is in the erect position, the body of the hyoid
bone, with its greater cornua, can be felt just below the body of the lower
jaw. About two centimetres, or three-quarters of an inch, below it is the
top of the thyroid cartilage, the anterior notch of which, or pomum Adama,
is recognizable,—but always more prominent in the male than in the female.
At the lower border of the thyroid cartilage there is a depression corre-
sponding to the crico-thyroid membrane, which intervenes between it and
the hoop of the cricoid cartilage (page 177). The latter is the most im-
portant landmark in the anterior part of the neck, as it is easily detected
in fat as well as in lean persons, of both sexes, and at all periods of life.
In drawing a comparison between the relative bearing of these parts in
the child and in the adult, it should not be overlooked that the larynx is
undeveloped before puberty, and that the changes in the jaws as to the
size and shape of their rami and the progressive development of the
alveolar processes have much to do with the relative position of some of
the parts in the vicinity. In bending back the head in the adult
(Plate 53, Fig. 1, and Plates 23 and 24), the space between the top of
190 THE REGION OF THE NECK.

the sternum and the chin is about double that which it measures when
the head is in the natural position, and it is chiefly increased between the
chin and the cricoid cartilage. In the child, however, with the head
similarly placed the space is increased between the cricoid cartilage and
the top of the sternum, because in the child the cricoid cartilage occupies
relatively a higher position in the neck, owing to the diminutive size of the
larynx. As the larynx becomes developed, the cricoid cartilage is depressed
toward the sternum, and the trachea, as well as the other parts of the neck,
assumes the adult arrangement. The distance between the cricoid cartilage
and the sternum is not more than four centimetres, or an inch and a half,
in the ordinary carriage of the head, and when the neck is stretched it is
increased very little over twelve millimetres, or half an inch. The upper
portion of the trachea can usually be felt just below the cricoid cartilage,
but its separate rings are indistinguishable, in consequence of the trachea
receding as it descends, so that at the root of the neck it is at a con-
siderable distance from the surface (Plates 24 and 25). When the head
is upright the cricoid cartilage is about opposite the spine of the fifth
cervical vertebra (Plates 1 and 12); when the head is bent backward, so as
fully to extend the neck, the cricoid cartilage is raised opposite the fourth
vertebra; and when the head is bent forward until the chin touches the
breast the cricoid cartilage is depressed, and corresponds to the sixth
vertebra. The general development of the neck varies in different indi-
viduals, being commensurate with the stature.

The difference in the length of the neck in the adult is sometimes more
apparent than real, frequently resulting from some peculiarity in the con-
formation of the shoulders. Its breadth is often variable. In children the
comparative length of this region is due to the slight development of
the face, the larynx being connected with the tongue and the hyoid bone;
and it is important to note that in childhood the top of the manubrium
sterni is higher in relation to the vertebral column than in the adult.

The skin over the anterior portion of the cervical region is thin,
delicate, and very elastic, being so loosely attached by the superficial
fascia to the deep fascia enveloping the underlying structures that it is
readily raised in folds.) The amount of fat in the subcutaneous tissue
THE REGION OF THE NECK. 191

varies in different localities, but it is apt to become diffused above the
hyoid bone, where it forms the redundancy called “double chin.” In
marked contrast to the skin in front is that over the nape of the neck,
where it is very dense and adherent to the sheaths of the muscles beneath,
so that when the head is turned backward the skin is thrown into parallel
transverse folds (Plate 53, Fig. 1). The peculiar toughness and low vas-
cularity of the superficial fascia in the latter locality render it liable to
become the seat of carbuncle, in consequence of which it is sometimes
called the “ carbuncular tissue.”

In close connection with the skin in front and at the sides of the
neck is the thin cutaneous muscle called the platysma myoides (Plate 17,
No. 7, and Plate 23, Fig. 1, No. 9). This muscle usually arises from the
skin over the chin, the body of the jaw, the cheek, and the masseteric
fascia, its fibres descending outward and forming a continuous sheet, which
is spread over the lateral portion of the neck and is inserted into the subcu-
taneous tissue over the pectoralis major and deltoid muscles. A few of the
fascicles of the upper portion blend with the tissues about the angle of the
mouth and radiate backward, being separated from the rest of the muscle,
and forming the musculus risoriws (page 121). Anteriorly the fibres are
very sparse and thin and cross those of the opposite platysma; and below
the chin they are frequently developed into muscular slips, forming the
so-called sphincter coll. This muscle serves as a protective covering to the
neck. It is supplied with nerves from the cervical plexus and the cervical
branch from the facial nerve, over which it lies. Within the meshes of
the platysma the external jugular vein appears, when it holds its usual
course, in a line from the angle of the jaw to the middle of the clavicle
(Plate 17, No. 5). The blue outline of this vein is almost always percep-
tible in life through the skin, and it is especially pronounced during
the acts of speaking, singing, and coughing. Also when the breath is
held and any great effort is made, these veins, as well as those of the fore-
head, become swollen. When the platysma is removed, the deep cervical
fascia is seen forming a close investment, having upon it the superficial
branches of the cervical plexus of nerves and the external and anterior
jugular veins (Plate 23, Fig. 2, No. 84). The eaternal jugular vein is
192 THE REGION OF THE NECK.

formed by the junction of the temporal and internal maxillary veins in
the substance of the parotid gland (page 134), at the lower border of
which it receives the transverse facial and posterior auricular veins. It
crosses obliquely the sterno-mastoid muscle, and generally takes a perpen-
dicular course to about half an inch above the middle of the clavicle,
where it pierces the deep fascia and terminates in the subclavian: vein.
Sometimes this vein joins the common jugular vein before it empties into
the subclavian, in which case the external jugular follows along the pos-
terior border of the sterno-mastoid muscle. The external jugular has two
pairs of valves: the lower, near its termination, are imperfect, but the
upper, four centimetres, or about an inch and a half, above the clavicle,
are more complete. Near the angle of the jaw the submazillary vein
(Plate 18, No. 17) establishes a communication between the external
jugular and facial veins.

The occipital vein joins the external jugular about the middle of its
course, and in the supra-clavicular fossa there is a confluence of veins
which are tributaries to it from the scapular region, and which are of
importance because they overlie the subclavian artery in the place where ~
it is usually sought (Plate 17, No. 8). The auricularis magnus nerve
turns round the posterior border of the sterno-mastoid muscle where the
external jugular vein crosses it, and passes upward to the parotid gland
in close proximity to the vein. The superficial cervical nerve passes under
the vein at this point, and divides into cutaneous branches which supply
the anterior surface of the neck (Plate 18, No. 26, and Plate 23, Fig. 2,
No. 31). The anterior jugular vein is usually insignificant, but it bears
a compensating supplemental relation to the external jugular, being
enlarged when that vein is small or deficient. There are sometimes
two anterior jugular veins running side by side along the anterior median
raphé of the neck, having short cross links between them above the
sternum. The anterior jugular ends either in the external jugular or
in the subclavian beneath the sternal end of the sterno-mastoid muscle.

The cutaneous nerves of the neck are the superficial branches of the
cervical plexus, which is formed by the intercommunication of the ante-
rior divisions of the four upper cervical nerves under the sterno-mastoid
THE REGION OF THE NECK. 1938

‘

muscle, and cannot be displayed unless that muscle is turned aside (Plates
20 and 21).

The upper cervical nerves, the most important of which is the great
occipital nerve, pertain more especially to the nape of the neck (Plate 22,
Fig. 1, Nos. 3 and 12). The nerves which supply the anterior part
of the neck appear at the posterior border of the sterno-mastoid muscle,
and are arranged in branches which pass upward, forward, and downward,
forming what is sometimes called the pes anserinus cervicis. The great
auricular and superficial cervical nerves are derived from the second and
third cervical nerves, and have been described in connection with the
external jugular vein. The small occipital nerve comes from the second
cervical nerve, and ascends along the posterior border of the sterno-mastoid
muscle to the back of the ear, communicating with the great occipital and
posterior auricular nerves (Plate 53, Fig. 1). It also sends a deep branch
to the spinal accessory nerve. The descending branches,are derived from
the third and fourth cervical nerves, and divide into the sternal, clavicular,
and acromial nerves, which supply the skin respectively in the neighbor-
hood of the sternum, clavicle, and ‘acromion (Plates 18, 19, and 23). The
cervical branch of the facial nerve (Plate 19) pierces the deep fascia at
the parotid gland, and, passing near the angle of the jaw, arches over the
upper part of the neck, supplying the platysma and the skin, and joins
the superficial cervical nerve.

There are a few superficial lymphatic glands in relation to the external
and anterior jugular veins which lie external to the deep cervical fascia.

The deep fascia in the cervical region, as elsewhere in the body,
constitutes an aponeurotic envelope over all the deeper parts, binding
them in position and preserving their relations to one another. From
its under surface are reflected over each structure prolongations peculiarly
modified to suit their several functions, so that they are encased in
appropriate sheaths. In certain localities these prolongations are more
strongly developed than in others, and by having special attachments play
an important part in the mechanism of this complex region. In others
they form dense partitions so arranged that they offer protection against

the evil effects of atmospheric pressure. It should be understood that this
25
194 THE REGION OF THE NECK.

*

is not an uninterrupted membrane, consisting of complete lamine, and
that not only is it modified and adapted to the requirements of muscles,
vessels, etc., but it is also here and there pierced by vessels and nerves
upon which it is reflected, and thus establishes communications between
its own recesses and those of the adjacent regions, the thorax and the
axillee.

The localities in which the deep fascia is particularly strong and
resisting are about the angle of the jaw, in front of the trachea, and
in the supra-clavicular fossa. The special attachments of this fascia are
of interest, as they often afford an explanation of the course which matter
takes when it forms in the neck; but much undue weight has been given to
them in this respect, for they do not by any means always set up efficient
barriers against or form natural passage-ways for the course of pus as
usually described. It is true, however, that here, as elsewhere, inflam-
matory action may induce plastic thickening in the deep fascia which
limits the growth of tumors and modifies the direction of their progress.
The fascia is attached posteriorly to the ligamentum nuche and to the
spinous processes of the cervical vertebree, closely adhering to the sub-
jacent muscles at the nape of the neck, and passes forward until it reaches
the sterno-mastoid muscle. There it splits into two layers, an external and
an internal, which respectively pass over and under the sterno-mastoid
muscle, and, uniting at its anterior border, so as to form for it a distinct
sheath, split again into lamelle, which in turn separate into leaflets.
The eaternal layer of the deep fascia is attached above to the mastoid
process and adjacent part of the occipital bone, to the zygoma, forming
in relation to the parotid gland the parotid fascia (page 130), and to
the border of the lower jaw. In the middle line of the neck this layer
blends with the corresponding layer from the opposite side and becomes
closely connected with the body of the hyoid bone. It forms sheaths
for the sterno-hyoid and sterno-thyroid muscles, and is attached below
to the clavicle and the top of the sternum. Below the thyroid body the
external layer of the fascia is divided into two lamelle, which are
inserted at the front and back borders of the top of the sternum,
including the sternal attachment of the sterno-mastoid muscle on each
THE REGION OF THE NECK. 195

side. This corresponds to the supra-sternal notch, and the interval
between the layers of fascia in this locality contains a few lymphatic
glands embedded in a variable quantity of fat, besides being traversed by
the anterior jugular vein. The internal layer of the deep fascia is very
complicated, as it separates into many subdivisions, which are in some
instances prolonged to join corresponding offsets from the fascia of
the opposite side and in others to blend with the deep fascia of adjacent
regions. Above it is attached to the base of the skull, and extends from
the styloid process to the angle of the jaw, forming the stylo-mazillary
ligament. It is prolonged, as the prevertebral fascia, over the longus colli
muscles, separating them from the posterior wall of the pharynx, and
descends behind the cesophagus into the thorax, where it joins with the
anterior common spinous ligament. It is extended across the trachea
under the sterno-thyroid muscles, and invests the thyroid body.

The cellular tissue between the prevertebral fascia and the pharyngeal
constrictor muscles is loose, and the seat of post-pharyngeal or retro-
pharyngeal abscesses, which instead of opening into the pharynx are
often guided by the fascia behind the carotid vessels to the outer surface
of the neck. A reflection of the prevertebral fascia has an attachment
to the transverse processes of the cervical vertebree which forms sheaths
for the scaleni muscles and extends over the cords of the brachial
plexus of nerves, to blend with the costo-coracoid membrane in relation
to the subclavius muscle. The sympathetic nerve is placed between the
prevertebral and post-pharyngeal layers of the fascia. .

In relation to the carotid artery, internal jugular vein, and pneumo-
gastric nerve an expansion is given off from the under surface of the
sheath of the sterno-mastoid muscle which blends with a leaflet from the
prevertebral fascia and becomes considerably condensed, so that it forms
a common sheath for these structures, which are also separated from one
another by delicate septa. By means of the carotid sheath this layer of
the deep cervical fascia becomes continuous with the pericardium, and the
heart thus receives support from both sides of the neck.

A reflection of the fascia is looped over the intermediate tendon of
the omo-hyoid muscle, which it binds to the first rib, and is prolonged
ONIAA PRONE

29,
30.
31.

the lines of their ribs, as they are found to be in the recent state.

PLATE 28.

Front view of a natural (ligamentous) skeleton of a European male aged thirty-eight years, showing the landmarks
with their relations to the surface coverings.

. The right temporal ridge.
. The right supra-orbital foramen.
. The squamous suture.

The external angular orbital process.
The sphenoidal fissure in the back of the right orbit.
The infra-orbital foramen.

. The right malar bone.
. The incisor teeth.

The angle of the lower jaw—the gonion.

. The mental foramen.

. The right clavicle.

. The manubrium sterni.

. The sternal end of the first rib.

. The second rib.

. The junction of the cartilage of the third rib with the

sternum (corresponding to the position of the base
of the heart).

. The third rib.

. The fourth rib. (This line passes over the right nipple.)
. The right humerus.

. The right fifth rib. .
. The right sixth rib.

. The ensiform cartilage.

. The right seventh rib.

. The right twelfth rib.

. The right eighth rib.

. The right ninth rib.

. The cartilage of the right tenth rib.

. The right radius.

The anterior superior spine of the ilium.
The anterior inferior spine of the ilium.
The great sciatic foramen.

The lesser sciatic foramen.

 

32.
33.

49,
50.
51.

52.
53.
54,
55.
56.
57.
58,
59.
60,

The great trochanter of the femur.
The ilio-femoral ligament, over the capsular ligament
of the hip.

. The lesser trochanter of the femur.

. The left frontal eminence.

. The glabella,

. The nasion,

. The sphenoidal fissure in the back of the left orbit.
. The septum nasi.

. The infra-orbital foramen.

. The ramus of the inferior maxillary bone.

. The mental foramen.

. The symphysis of the lower jaw.

. The acromion process of the scapula.

. The coracoid process of the scapula,

. The sternal end of the first rib.

. The venter of the left scapula.

. The sternal ridge at the junction of the first and second

pieces of the sternum.

The gladiolus.

The fourth rib. (This line passes over the left nipple.)

The junction of the left fifth rib with its cartilage
(where the apex of the heart beats in life).

The left sixth rib.

The cartilage of the left seventh rib.

The internal condyle of the left humerus.

The head of the radius.

The left radius.

The left ulna.

The left Poupart ligament.

The styloid process of the radius.

The left carpus,

N.B.—In this preparation. owing to the effect of drying, the second, third, and fourth costal cartilages are not in

Compare Plate 29,
Wort, 0

%
Plate 28

 

 

 

 

55
2K

28 a
6

2
29 eS 7

30

3)

66

 

 

 

Copyright (8 91by GeohseMe CuewcanM.D.

Dissected, Photographed and Colored’ from Nature oy GEORGE Me. Crean, 0.

Armstrong & Ca Lith Basion
THE REGION OF THE NECK. 197

over the subclavian vessels into the axilla. Back of the sternum there
is a continuation of this layer of the deep fascia, which passes along
the anterior mediastinum: the pus from a cervical abscess will sometimes
travel along this route and point at the side of the xiphoid appendix on
the surface of the abdomen. The arrangement of the layers of the deep
cervical fascia in relation to the top of the sternum, to the first rib, and
to the clavicle is such that the soft parts at the upper opening of the chest
are protected against the pressure of the atmosphere during inspiration.

The deep cervical fascia is not normally strong and unyielding, and
cannot properly be compared with the fascia lata, but it may become so
under the influence of pressure and inflammation; and in many instances
where growths or abscesses in this region have been influenced in their
course by the denseness of the surrounding fascia, the growth or abscess
has itself induced the change. This is especially noticeable where the
morbid condition has become chronic.

The sterno-cleido-mastoid muscle (Plates 16, 18, 19, and 23) is the
great muscular landmark at the side of the neck, which serves as a guide
to the position of the important vessels with which it is in immediate rela-
tion. It arises by a thick, round tendon from the upper and outer surface
of the manubrium sterni, internal to the sterno-clavicular joint, and by a
flat, fleshy, and tendinous origin from the adjacent portion of the clavicle.
Between these origins there is a variable interval, which is filled with a
double layer of the cervical fascia. The sternal fibres ascend over the
sterno-clavicular joint and join with the clavicular fibres, so that at the
middle of the muscle its substance is strong and somewhat contracted, but
toward its insertion it flattens out, to be attached to the mastoid process, the
temporal bone behind the process, and the contiguous part of the upper
curved line on the occipital bone. The fibres composing the external and
clavicular portions, if carefully examined, will be found to overlap one
another, so that the sternal fibres occupy the outer and more conspicuous
position, while the clavicular fibres are deeper and mainly attached to the
apex of the mastoid process. These peculiarities of the insertions of the
fibres of this muscle explain the different actions of which it is capable.
This will be better understood by referring to the landmarks of the articu-
198 THE REGION OF THE NECK.

lated skeleton (Plate 1) than by referring to a detached skull (Plate 2), and
it should be remembered that a line drawn from one mastoid process to the
other will bisect the condyloid processes, as previously stated, and that the
vertical axis of the skull corresponds to a perpendicular line from the vertex
to the inter-mastoid line. Ordinarily the united action of the two sterno-
mastoid muscles maintains the head in the erect position with the face
directed forward, but if the action of the sternal fibres, which are attached
to the temporal and occipital bones behind the mastoid process, is greatest,
the head will be tilted backward, with the face upward, while if the action
of the clavicular fibres, which are inserted into the apex of the mastoid
process, predominates, the head will be bowed forward. This action is
marked in raising the head from the recumbent position, and both actions
may be demonstrated by the application of electrical stimulation (Plate 53,
Fig. 1). In considering the action of the sterno-mastoid muscle the expan-
sion of the deep fascia, which connects the upper part of its anterior border
with the lower jaw, should not be overlooked, for it probably assists ma-
terially the clavicular fibres. The action of one sterno-mastoid muscle
draws the head obliquely toward the opposite shoulder, co-operating with
the splenius muscle of the other side. The condition known as “wry-neck”
is generally due to the spasmodic contraction of one sterno-mastoid muscle.
When the head is fixed, the sterno-mastoid muscles elevate the sternum in
forced inspiration. Each muscle is supplied principally by the spinal
accessory nerve, which enters close to the mastoid process, together with
the sterno-mastoid branch of the occipital artery. It also receives nerves
from the second and third cervical nerves, and arteries from the superior
thyroid and supra-scapular arteries.

The side of the neck may be considered as divided by the oblique
direction of the sterno-mastoid muscle into triangular spaces, the anterior
and posterior cervical triangles. The anterior triangle is inverted, its
base being formed by the body of the lower jaw, and its sides by the
middle line and the anterior border of the sterno-mastoid. The posterior
triangle has the clavicle for its base, while its sides are defined by the
posterior border of the sterno-mastoid and the anterior border of the
trapezius muscle (Plate 16). The neck is further subdivided into smaller
THE REGION OF THE NECK. 199

triangles by the disposition of the digastric and omo-hyoid muscles beneath
the sterno-mastoid. The digastric muscle consists of two muscular portions,
united by an intermediate tendon, which pierces the tendon of the stylo-
hyoid muscle and is attached to the body of the hyoid bone by a loop of
the deep fascia (Plate 25, No. 4). The posterior portion arises from the
digastric fossa on the temporal bone, back of the mastoid process. The
anterior portion is attached to the lower jaw near the symphysis. These
two portions, with the body of the lower jaw, constitute the submazillary or
digastric ‘triangle. When the platysma is removed from this locality the
deep fascia presents a dense covering to the contents of this space, the
chief of which is the submaxillary salivary gland (Plate 18, No. 20, and
Plate 13, Fig. 2, No. 6), which has already been described (page 164), as
well as the relations of the facial and lingual arteries, for which this trian-
gular space is usually topographically surveyed. The submaxillary vein,
which joins the facial vein with the external jugular, is in the superficial
fascia, in close proximity to the jaw (Plate 18, No. 17), and there are from
six to ten lymphatic glands (Plate 16), some above and some beneath the
salivary gland, which receive the lymphatic vessels from the face, the
tongue, and the tonsils, already spoken of in the description of these parts.
The stylo-hyoid muscle is a slendersband of fibres, originally separated from
the posterior portion of the digastric, with which it is in close relation at
its inner side. Its upper attachment is at the outer and back surface of the
styloid process, and its lower at the body of the hyoid bone near the lesser
cornu, where it is pierced by the middle tendon of the digastric. The
nerves which supply the posterior portion of the digastric and the stylo-
hyoid muscles come from the facial nerve, and leave the lower border of the
parotid gland immediately above. These muscles overlie the external and
internal carotid arteries, the internal jugular vein, and the pneumogastric
and hypoglossal nerves (Plate 13, Fig. 2, and Plate 22, Fig. 2). The
anterior portion of the digastric muscle is superficial, and rests upon the
mylo-hyoid muscle anterior to the submaxillary gland (Plates 23 and 25).
The inner margins of the anterior portions of the two digastric muscles are
often connected by fleshy fibres, but generally by connective tissue. Their
nerves are derived from the mylo-hyoid nerves. The anterior and pos-
200 THE REGION OF THE NECK.

terior portions of the digastric muscle always act together, but the effect
of their action depends upon which two of the three points of attachment
are fixed. If the jaw and skull are both fixed, the muscle raises the hyoid
bone, as in swallowing; if the skull and hyoid bone are fixed, the lower
jaw is depressed, as in yawning; if the chin is supported so that the jaw
and hyoid bone are fixed, the muscle can draw the skull backward. The
digastric and stylo-hyoid muscles, with the mylo-hyoid and genio-hyoid
muscles, described in relation to the tongue (page 165), are classified as
the supra-hyoid muscles.

The omo-hyoid muscle is digastric, consisting of two fleshy portions
connected by an intermediate tendon. Its posterior portion arises beneath
the trapezius muscle from the superior border of the scapula, usually
including the supra-scapular notch and its ligament, and passes forward
and upward to the level of the cricoid cartilage, being attached to the
clavicle by a fold of deep fascia which loops around its intermediate tendon
under the sterno-mastoid muscle. The anterior portion passes vertically
upward close to the outer border of the sterno-hyoid muscle, and is
attached to the lower border of the hyoid bone. The course of this
muscle does not change in contraction, and always maintains an obtuse
angle, so that it is a reliable guide to.the position of the great carotid
vessels, directly over the sheath of which it passes at the point where the
anterior and posterior portions of the muscle meet, on a level with the cri-
coid cartilage, as just stated. The fascial expansion which binds the central
tendon to the clavicle is usually reflected to the first rib, and appears to
offer resistance to the pressure of the atmosphere upon the internal jugular
vein and the apex of the pleura which it covers. Occasionally fleshy fibres
are developed in this reflection of the fascia. The contraction of the omo-
hyoid muscles takes place only during inspiration, and, owing to their
influence upon the fascia enveloping the great venous trunks at the root of
-the neck, a dilatation of these vessels is coincident with the dilatation of the
thorax, so that the flow of the blood toward the heart is facilitated. This
also indicates the danger of the entrance of air in wounds involving these
veins. The subdivisions of the side of the neck which may be mapped
out by the disposition of the omo-hyoid muscle are known as the superior
THE REGION OF THE NECK. 201

and inferior carotid triangles anterior to the sterno-mastoid muscle, and the
occipital and supra-clavicular triangles posterior to it. The superior carotid
triangle has for its three sides the posterior portion of the digastric muscle,
the sterno-mastoid muscle, and the anterior portion of the omo-hyoid
muscle. The inferior carotid triangle is bounded by the omo-hyoid and
sterno-mastoid muscles, above and below, and in front by the middle
line of the neck.

These carotid triangles have been so called because they were considered
to bear reference to the course of the carotid artery and the internal jugular
vein, and to elucidate the topographical study of this very complex region.
They are very misleading, and time is often wasted in attempting to acquire
or recall their boundaries. The carotid artery is not within the limits
of the inferior triangle at all, as the sternal end of the sterno-mastoid
muscle completely overlaps the sheath of the great vessels, which is in
reality in relation to the interval between the sternal and clavicular
origins of that muscle. A needle introduced upon the right side above
the clavicle through this interval would pierce the bifurcation of the
innominate artery, and on the left side the common carotid artery (Plate
14, Fig. 2, No. 6). The course of the carotid arteries on both sides from
this point to their bifurcation is similar, and approximately may be con-
sidered as corresponding to the anterior borders of the sterno-mastoid
muscles when either of them is brought into relief by turning theshead
to the opposite side. A line drawn transversely across the neck from
the fifth cervical vertebra to the cricoid cartilage will indicate the position
where the omo-hyoid muscle crosses the sheath of the great vessels. Above
this point the carotid artery is superficial; below it is deeply placed and
covered with a quantity of fatty tissue containing many veins, nerves, and
lymphatics. It is this point of crossing of the omo-hyoid muscle which
should be sought for in any operation upon the carotid artery; and by
making an incision opposite the cricoid cartilage along the border of the
sterno-mastoid muscle it can be readily reached. The bifurcation of the
common carotid into the external and internal carotid arteries usually
occurs opposite the top of the thyroid cartilage, which is on a level with

the body of the third cervical vertebra, but it may be a little above or
26
PLATE

29.

The anterior wall of the thorax and upper part of the abdomen removed to show the relations of the heart, lungs,
diaphragm, liver, stomach, and spleen to the ribs and their sternal cartilages. The lungs are inflated (as in full inspira-
tion) to indicate the so-called area of the heart’s dulness. From a male subject about forty years old, with normal

condition of the organs.

1, The supra-sternal notch. 26.
2. The right first rib. 27.
3. The right second rib. 28.

4, The upper lobe of the right lung.
5. The right third rib.

6. The base of the heart. 29.
7. Position of the tricuspid valves. 30.
8. The right fourth rib. 31.
9, The right nipple. 32.
10. The right auricle of the heart. 33.
11. The middle lobe of the right lung. 34,
12. The right fifth rib. 35.
18, The lower lobe of the right lung, resting on the dia- | 36.
phragm and overlapping the liver. 37.

14. The right sixth rib. 38.

15. The ensiform cartilage.

16. The upper surface of the diaphragm, seen through the 389.
space between the sixth and seventh ribs. 40.
17. The cartilage of the right eighth rib. 41,

18. The right seventh rib.

19. The left lobe of the liver. 42,
20. The right eighth rib, in this case a true rib, having an | 43.
independent sternal cartilage. 44,
21. The cartilage of the right ninth rib, in its relation to | 45.
the fundus of the gall-bladder. 46.
22, The cartilage of the right tenth rib. 47,

23. The lower margin of the right lobe of the liver.

24, The great omentum. 48.

 

25, The manubrium.

The left first rib.

The left second rib.

The ridge at the junction of the manubrium and gladi-
olus of the sternum, where it receives the cartilages
of the second ribs.

The left third rib.

The position of the pulmonary valves.

The upper lobe of the left lung.

The left fourth rib.

The position of the mitral valve.

The left nipple.

The left fifth rib.

The right ventricle of the heart.

The position of the apex beat in the adult.

The upper surface of the diaphragm, seen between the
fifth and sixth ribs.

The left sixth rib.

The lower border of the left lung.

The cartilage of the left eighth rib, independently con-
nected with the sternum.

The left seventh rib.

The left eighth rib.

The fundus of the stomach, in ordinary distention.

The cartilage of the left ninth rib.

The cartilage of the left tenth rib.

The lower border of the spleen, in its relation to the
cartilage of the tenth rib.

The branches of the gastro-epiploica dextra artery.

N. B.—The subject upon which this dissection was made presented the rare anomaly of a distinct eighth true rib on

either side. This is well shown in the plate.
 

sotographed ano’ Colored from Nature by Georce Mc, Cretan, MD,

 

Copyright /89/.by GeorceMc Cie AnMD.

Von I

Armstrong § Go Lith Boston

 
THE REGION OF THE NECK. 203

below this point. The bifurcation is often the seat of aneurism or dilata-
tion, in consequence of the resistance here naturally offered to the current
of the blood. The eaternal carotid artery, just after its origin, gives off the
ascending pharyngeal artery, which runs up between the external and
internal carotids to its distribution (page 175), and then in successive
order anteriorly the superior thyroid (page 184), lingual (page 166), and
facial (page 123) arteries, and terminates in the parotid gland in the
internal maxillary and temporal arteries (page 134). Posteriorly the
branches from the external carotid are the occipital and posterior auricular
arteries (page 8). The relative position which the external and internal
carotid arteries hold to each other is worthy of careful notice. At first
they are on the same plane, but the external soon crosses in front of
the internal to enter the under surface of the upper portion of the
parotid gland. The internal ascends close by the side of the pharynx
to the base of the skull (Plate 13, Figs. 1 and 8), which it enters by
the carotid canal in the apex of the temporal bone. Between the ex-
ternal and internal carotid arteries, just above their bifurcation, there is a
long, grayish-colored body, the inter-carotie body, which consists of a vas-
cular net-work of tiny vessels from the external carotid, interwoven with
some non-medullated nerves and ganglion cells and connective tissue. It
is the remains of one of the fcetal visceral clefts. The internal jugular
vein receives the blood from the brain by the lateral sinus, and commences
at the jugular foramen, where it is joined by the inferior petrosal sinus and
presents a slight enlargement, the jugular sinus. The jugular foramen is
formed by the apposition of the jugular fossee of the occipital and tem-
poral bones, and is behind the opening of the carotid canal, two and one-
half centimetres, or about an inch, from the surface over the mastoid
process. The vein descends on the outer side of the internal carotid
artery, and, after receiving the temporo-facial vein, becomes ensheathed
with the common carotid artery, and pursues its course as the common
jugular vein on the outer side of that vessel, until it empties into the
subclavian vein at a right angle and forms the innominate or brachio-
cephalic vein. The internal jugular receives the blood from the pharyn-
geal, occipital, facial, lingual, superior thyroid, and middle thyroid veins.
204 THE REGION OF THE NECK.

The jugular foramen also gives exit from the cranium to the pneumo-
gastric, spinal accessory, and glosso-pharyngeal nerves.

The pneumogastric nerve (Plate 21, No. 43, Plate 36, No. 61, and
Plate 37, No. 82) within the foramen is enclosed in a sheath of the
dura mater and arachnoid membrane, with the spinal accessory nerve.
There is upon its root a small ganglion (Arnold’s) which receives a branch
from the accompanying nerve. About twelve millimetres, or half an inch,
below the ganglion on the root there is another ganglionic enlargement,
the ganglion of the trunk, which involves only a part of the nerve.
The pneumogastric is probably at its origin a nerve of sensation only, but
as it is joined by filaments from the hypoglossal and from the first and
second cervical nerves as well as from the superior cervical sympathetic
ganglion, it becomes a compound nerve and resembles a spinal nerve. It
descends upon the rectus capitis anticus major and longus colli muscles in
front of the cervical vertebra, and at the upper part of the neck becomes
ensheathed with the internal carotid artery and internal jugular vein,
holding a position posterior to them. This position of the pneumogastric
nerve is maintained with regard to the common carotid artery and internal
jugular vein until the root of the neck is reached, where the nerve, as well
as the vessels, holds different relations on the two sides, which are specially
described on page 317. In the upper part of the neck the pneumogastric
nerve furnishes branches to the ear, to the pharynx, and to the larynx.
The auricular (Arnold’s) branch arises from the lower end of the jugular
ganglion, and, passing through a canal in the outer wall of the jugular
fossa of the temporal bone, enters the aqueduct of Fallopius and escapes
to the outer surface by the auricular fissure, where it communicates
with the posterior auricular nerve and supplies the back of the concha
(page 63). The pharyngeal branch arises from the upper part of the
ganglion of the trunk, and, being joined by filaments from the spinal
accessory and sympathetic nerves, passes to the inner side of the internal
carotid artery and forms the pharyngeal plexus upon the middle constrictor
muscle (page 175). The superior laryngeal branch is derived from the
middle of the ganglion of the trunk, and, passing downward behind the
internal carotid artery, divides into the internal and external laryngeal
THE REGION OF THE NECK. 205

nerves (page 185). In two dissections made within the last year the author
has found distinct branches passing from the pneumogastric on the left
side to the brachial plexus (one of these is seen in Plate 36).

The glosso-pharyngeal nerve leaves the jugular foramen in a separate
sheath of the dura mater, in front of the spinal accessory and pneu-
mogastric nerves. This nerve at its exit consists of two cords, which
coalesce in the jugular foramen and form a double ganglionic swelling,
the upper part of which is the jugular (or Ehrenritter’s) ganglion and
the lower is the petrosal (or Andersch’s) ganglion. The trunk of the
nerve below the ganglionic enlargement descends between the internal
carotid artery and internal jugular vein until it reaches the lower border
of the stylo-pharyngeus muscle, whence it is distributed to the tongue
(page 167). The hypoglossal nerve, after its exit from the skull through
the anterior condyloid foramen, is in close connection with the ganglion
of the trunk of the pneumogastric beneath the internal carotid artery
and internal jugular vein, between which it comes forward and below
the posterior portion of the digastric muscle curves round the occip-
ital artery on its way to the tongue (page 167). As it crosses the
occipital artery the branch called the descendens hypoglossi is given off
(Plate 21, No. 41). At first this little nerve enters the sheath of the
carotid vessels, but about the level of the hyoid bone it comes through
the sheath and runs along on its surface to a point below where the
omo-hyoid muscle crosses. This nerve can usually be seen as a white
thread on the surface of the carotid sheath, and is. generally a reliable
indication of its position. The descendens hypogloss: forms a loop, the
ansa hypoglossi, with the communicating branches from the second and
third cervical nerves (Plate 21), from which are derived the nerves which
supply the omo-hyoid, sterno-hyoid, and sterno-thyroid muscles,—the
depressor muscles of the hyoid bone. The descendens hypoglossi appears
to consist of fibres mainly derived from a branch from the upper two
cervical nerves.

The spinal accessory nerve leaves the skull in a common sheath of dura
mater with the pneumogastric nerve at the middle of the jugular foramen.
The fibres of the original portions of this nerve, the accessory and the
206 THE REGION OF THE NECK.

spinal, intermingle at the foramen, but separate into two portions again
below the foramen. The accessory portion sends a few filaments to join
the ganglion at the root of the pneumogastric nerve, and also filaments
to the pharyngeal and superior laryngeal. branches as they leave the
ganglion of the trunk of that nerve. Below the latter ganglion the
remaining accessory fibres are incorporated with the pneumogastric.
The spinal portion, after leaving the accessory, curves backward and
outward across the internal jugular vein and the transverse process of the
atlas vertebra behind the stylo-hyoid and digastric muscles. It pierces
the upper portion of the sterno-mastoid muscle in company. with the
sterno-mastoid branch of the occipital artery. Leaving the sterno-mastoid
muscle, the nerve crosses obliquely the occipital division of the posterior
triangular space of the neck to the under surface of the trapezius muscle,
and is joined by branches of the second, third, and fourth cervical nerves
(Plate 20, No. 58, and Plate 21, No. 10).

The occipital triangle is bounded in front, behind, and below respec-
tively by the sterno-mastoid, trapezius, and omo-hyoid muscles. Within
this space (Plate 21) are found the deep cervical plexus of nerves, the
spinal accessory nerve as above described, and a chain of lymphatic
glands in relation to the posterior border of the sterno-mastoid muscle,
extending from the mastoid process to the root of the neck (Plate 16).
The transversalis colli artery and vein (Plate 25), and the superficial
cervical branch from the transversalis colli artery to the trapezius muscle,
pass outwardly in the lower portion of this space.

The deep cervical plexus of nerves (Plates 20 and 21) consists of inter-
communicating branches between the anterior divisions of the upper four
cervical nerves, which rest upon the levator anguli scapule and scalenus
medius muscles, close to the transverse processes of the upper four cer-
vical vertebre. Each nerve forming the plexus, with the exception of
the first, divides into ascending and descending branches. The super-
Jicial nerves of the plexus have been already described (page 198). The
deep nerves consist of external and internal branches. The external
branches are, besides the communicating nerves to the spinal accessory,
muscular nerves to the contiguous muscles,—viz., the sterno-mastoid,
THE REGION OF THE NECK. 207

scalenus medius, levator anguli scapule, and trapezius. The méernal
branches consist of the communicantes (from the second and _ third
nerves), which, looping round the internal jugular vein, join the descen-
dens hypoglossi, muscular branches from the first nerve to the prever-
tebral muscles,—viz., the recti antici, rectus lateralis, and longus colli,—
and branches to the hypoglossal, pneumogastric, and sympathetic nerves,
and the phrenic, which arises from the third, fourth, and fifth cervical
nerves and descends toward the root of the neck over the scalenus
anticus muscle. .

The supra-clavicular triangle, called also the subclavian triangle, be-
cause it contains the subclavian artery, is bounded below by the clavicle, in
front by the clavicular origin of the sterno-mastoid muscle, and above by
the posterior portion of the omo-hyoid muscle. The area of this space is
variable, and depends upon the obliquity of the omo-hyoid muscle and
the extent of the clavicular attachments of the sterno-mastoid and trape-
zius muscles. The contents of the supra-clavicular triangle are described
with the other parts at the root of the neck. They, together with the
contents of the occipital triangle, rest upon the deep muscles of the neck,
the splenius (capitis et colli), the levator anguli scapule, the scalenus
medius and posticus, and part of the serratus magnus.

The splenius muscle (Plate 16, No. 7, Plate 19, No. 25, Plate 22,
Fig. 1, Nos. 5 and 14) arises by tendinous slips from the spinous
processes of the six upper dorsal and seventh cervical vertebre, from
the supra-spinous ligament, and from the lower portion of the ligamentum
nuche. The fleshy fibres are directed upward and outward, and are
divided into two portions, an inner and an outer. The inner portion is
inserted into the mastoid process and into the outer part of the superior
curved line of the occipital bone beneath the sterno-mastoid muscle, and
is called the splenius capitis. The outer portion is inserted into the
posterior tubercles of the transverse processes of the three upper cervical
vertebre, and is called the splenius colli. These muscles are supplied by
the external branches of the posterior divisions of the cervical nerves.
The action of the splenii muscles aids that of the sterno-mastoid muscles.
When the two muscles on both sides contract together, they assist in
208 THE REGION OF THE NECK.

holding the head erect. The action of either of them (the two portions
working together) is to draw the head and the upper cervical vertebre
toward its own side. When this contraction is permanent it may pro-
duce “ wry-neck,” and may be confounded with the action of the opposite
sterno-mastoid muscle, which produces the same effect (page 198).

The levator anguli scapule (Plate 16, No. 8) arises tendinously from
the transverse processes of the four upper cervical vertebre, the two upper
slips being the largest. These unite to form a prismatic muscle which
descends along the side of the neck and is inserted into the posterior
border of the scapula from the superior angle to the root of the spine.
It receives branches from the third and fourth cervical nerves of the deep
cervical plexus, and a branch from the fifth cervical nerve. When this
muscle is brought into action, it raises the posterior angle of the scapula,
as in shrugging the shoulders.

The cervical portion of the trapezius muscle covers the preceding
muscles. It is superficial (Plate 22, Fig. 1, No. 4) at the back of the
neck, and constitutes the lateral bulge on each side of the middle depression
over the spines of the cervical vertebre.

The trapezius arises from a variable extent of the inner portion of
the superior curved line on the occipital bone, from the ligamentum
nuche, from the spinous process of the vertebra prominens, and from
the spines of all the dorsal vertebree and their supra-spinous ligaments.
Each trapezius muscle is triangular in shape, but the two together form
a trapezoid, and between the sixth cervical and the third dorsal vertebra
their origin presents a glistening semi-oval aponeurosis, the speculum rhom-
boideum. The fibres of each muscle converge from their extensive vertical
origin toward the shoulder, to be inserted upon the scapula exactly corre-
sponding to the origin of the deltoid muscle (Plate 16, No. 10). The upper
fibres pass downward and outward, to be inserted into the upper edge of
the clavicle, usually upon its outer third, but often extending forward as
far as the posterior border of the clavicular portion of the sterno-mastoid
muscle; the middle fibres pass transversely outward to the inner border of
the acromion process and upper margin of the spine of the scapula; and
the lower fibres pass upward and outward and are inserted by a thin tendon
THE REGION OF THE NEOK. 209

into the tubercle of the spine of the scapula. There is always a layer of
loose connective tissue or a mucous bursa interposed between the tendon
and the triangular surface at the back of the scapula. The trapezius is
supplied by the spinal accessory nerve, and by the deep branches of
the cervical plexus. Its nutrient arteries are derived from the superficialis
colli and the dorsal branches of the intercostal arteries (Plate 22, Fig. 1,
No. 10). When both trapezius muscles act from below they draw the
head backward, or one muscle acting in the same manner will turn the
head backward to the corresponding side. The whole of each muscle has
the power to retract the scapula, and, by rotating it, to raise the shoulder.

Beneath the trapezius and splenius muscles at the back of the neck is
the powerful complexus muscle. ‘This muscle is broad and thick, and arises
usually by seven tendons from the tips of the transverse processes of the
three upper dorsal vertebree and the vertebra prominens and from the
articular processes of the sixth, fifth, and fourth cervical vertebra. It is
inserted into the depression between the two occipital curved lines near the
median ridge. Very often this muscle presents a transverse tendinous
intersection, and a separate fasciculus is sometimes specialized at the spinous
border, which, because it has a longitudinal tendon in its centre, is called
the biventer cervicis. This muscle is separated from its fellow by the
ligamentum nuche, which is practically a continuation upward of the
supra-spinous ligament. It consists of fibro-elastic tissue, and extends
from the spinous processes of all the cervical vertebra, except the atlas,
to the external occipital protuberance. In a few instances muscular fibres
have been found in place of this ligament, but in man it is a rudiment
of the strong elastic ligament which enables some of the lower animals
to sustain the weight of the head.

At the outer side of the complexus are the ¢rachelo-mastoid and trans-
versalis colli muscles, which are accessory portions of the longissimus dorsi
continued to the head and neck.

’ The trachelo-mastoid muscle arises from the upper five dorsal transverse
processes and from the lower four cervical articular processes by tendinous
slips which unite to be inserted into the back of the mastoid process

beneath the sterno-mastoid and splenius muscles. The transversalis colli
27
21.

22.
23.
24,

PLATE 30.

The lungs inflated, so as to demonstrate the approximation of their edges over the heart, as in full inspiration.

. The right common carotid artery.

. The right internal jugular vein.

. The right scalenus anticus muscle,

. A rubber tube introduced into the trachea for the pur-

pose of-inflating the lungs.

. The right transversalis colli artery and vein. i
. The right pneumogastric nerve.

. The sternal end of the right clavicle.

. The innominate artery.

2 The right subclavian vein and artery.

The sternal end of the right first rib.

. The right innominate vein.

. The ascending portion of the aorta.

. The right second rib.

. The right third rib.

15. The cleft between the upper and lower principal lobes

of the right lung.

. The right lung.

. The right fourth rib.

. The right fifth rib.

. The cleft in the lower portion of the right lung, indi-

cating its division into the so-called middle and in-
ferior lobes.

. The right sixth rib.

The anterior lower border of the right lung (as in full
inspiration).

The upper surface of the diaphragm.

The right seventh rib.

The left common carotid artery.

 

25.
26.
27,
28,
29.
30.
31.
32,
33.
34,
35.
36.
37,
38.

39.
40.
41,
42,

43.
. The right ventricle of the heart coveredsvith the peri-

44,

45.
46.

47.
48,

The left brachial plexus of nerves.

The left internal jugular vein.

The trachea at. the root of the neck.

The left scalenus anticus muscle.

The left pneumogastric nerve.

The remains of the left coraco-clavicular membrane.

The sternal end of the left clavicle.

The left subclavian artery.

The left subclavian vein.

The sternal end of the left first rib.

The left innominate vein.

The left pneumogastric nerve.

The left second rib.

The approximation of the edges of the lungs in the
median line, covering the root of the heart, as occurs
in full inspiration.

The left third rib.

The upper lobe of the left lung.

The left fourth rib.

The notch in the anterior edge of the left lung in rela-

tion to the apex of the heart.

The left fifth rib.

cardium.

The left sixth rib.

The anterior lower border of the left lung (as in full
inspiration).

The left.seventh rib.

The left eighth rib.

N. B.—This and the succeeding plates (31, 82, and 33) were taken from a male subject about thirty-two years of age,
who died from choking. The lungs were absolutely healthy. The pleuree were removed in the dissection.
Plate 30

90,by GeorGel

 

ssected, Photographed and Colored from Nature by Georce Mc. Ciettaw, M 2.
THE REGION OF THE NECK. 211

muscle arises by delicate tendons from the six upper dorsal transverse
processes, and is inserted by as many tendons into the posterior tubercles
of the lower six cervical transverse processes. The last two muscles are
supplied by external branches from the posterior divisions of the cervical
nerves, the complexus receiving internal branches of these nerves,
together with branches from the sub-occipital and great occipital nerves.
The action of the trachelo-mastoid and transversalis colli muscles assists
the overlying muscles in holding the head erect or in turning it back-
ward to one or the other side according as both pairs of the muscles act
together or the individual muscles act severally. The occipital artery, after
leaving its groove in the temporal bone back of the mastoid process, passes
horizontally underneath the sterno-mastoid, splenius, and trachelo-mastoid

muscles to the complexus (Plate 22, Fig. 1), upon the outer surface of.

which it turns upward, and, piercing the attachment of the trapezius, winds
tortuously over the occiput, dividing into numerous branches, which sup-
ply the tissues of the scalp posteriorly. The point where the occipital
artery reaches the scalp (Plate 21, No. 6) is about midway between the
external occipital protuberance and the mastoid process, and it also corre-
sponds to the position of the great occipital nerve, with which the vessel is
in close relation. The occipital artery furnishes nutrient vessels to the
digastric, stylo-hyoid, splenius, trachelo-mastoid, and sterno-mastoid muscles.
It also sends a branch to the back of the concha, and one or more menin-
geal branches which enter by the mastoid foramen or through the jugular
foramen to supply the neighboring part of the dura mater; but the most
important branch is the princeps cervicis, which passes downward from the
occipital between the complexus and splenius muscles and divides into
two branches. One of these is superficial, and, penetrating the splenius,
supplies the trapezius and anastomoses with the superficial cervical branch
of the transversalis colli; the other takes a deep course between the com-
plexus and semispinalis colli muscles and anastomoses with the vertebral
and often with the deep cervical branch from the superior intercostal
artery. By means of these anastomoses the collateral circulation is mainly
established after ligature of the carotid or subclavian artery.

The deeper muscles beneath the complexus are the prolongations of

|
212 THE REGION OF THE NECK.

the erector qgpine mass. They are of variable development in different
subjects, and are interesting because they assist the more superficial muscles
in holding. the head in the various positions while the body is upright.
The cervicalis ascendens is the upward continuation of the accessorius
muscle: it arises from the angles of the four or five upper ribs, and is
inserted by tendons into the posterior tubercles of the transverse processes
of the sixth, fifth, and fourth cervical vertebre. The spinalis colli is often
absent, but when it exists it connects the spines of the lower cervical verte-
bre, like the spinalis dorsi, and is inserted into the spinous process of the
axis vertebra. The cervical portion of the multifidus spine consists of a
series of muscular slips extending from the articular processes of the lower
four cervical vertebre, each of which passes obliquely to be inserted into
the spinous process of the vertebra above and the contiguous portions of
the lamine.

Besides the above there are the inter-spinales and the inter-transversales.
The former are more pronounced in the neck than they are in the back,
and extend between the spinous processes of the lower six cervical verte-
bree, while the latter pass between their transverse processes. The anterior
portions of the inter-transversales correspond to the intercostal muscles.
There are seven in the neck, where they are also most marked, and they
are arranged in pairs between the anterior and posterior tubercles of the
contiguous vertebre. All these deeper muscles are supplied with branches
from the internal posterior branches of the cervical nerves.

At the very top of the neck there are upon each side various small
muscles which are concerned in the movements of the head upon the
atlas and axis vertebre. They are specialized as follows. The rectus
capitis posticus major is the largest: it arises from the side of the spinous
process of the axis, and is inserted into the outer part of the lower curved
line on the occipital bone and the rough surface below it. The rectus
capitis posticus minor is deeper than, and internal to, the major: it
arises by a narrow tendon from the posterior tubercle of the atlas, and
is inserted by a fan-shaped expansion between the inner portion of the
inferior curved line and the foramen magnum. The action of these
muscles is to raise the head. The obliquus capitis inferior passes’ from
THE REGION OF THE NECK. 213

the spine of the axis to the under surface of the transverse process of
the atlas. The obliquus capitis superior extends from the upper surface
of the transverse process of the atlas, just above the insertion of the
former, to the interval between the occipital curved lines. The action of
the inferior oblique is to turn the head round to the same side by rotating
the atlas upon the axis vertebra. The great occipital nerve supplies it
with a branch as it turns round its lower border. The action of the
superior oblique is to draw the occiput toward the spine. This muscle
and the two recti postici receive branches from the sub-occipital nerve,
which is in close relation to them. The so-called sub-occipital triangle
is formed by the disposition of the two oblique muscles with the rectus
capitis posticus major, the obliquus superior being on the outer side, the
rectus capitis posticus major on the inner, and the obliquus inferior on
the lower. This triangle contains the arch of the atlas vertebra, with
the vertebral artery lying in a groove on its upper surface (page 215).
The posterior division of the sub-occipital (first spinal nerve) is placed
between the artery and the bone.

Beneath the multifidus muscles, upon the lamine of the cervical
vertebre, there is on both sides of the neck a plexus of large veins,
the cervico-dorsal spinal ves, which communicate freely with the
veins of the vertebral canal through the interlaminar ligaments. The
interlaminar ligaments, or ligamenta subflava, are thick masses of elastic
yellow fibrous tissue which fill in the intervals between the arches of the
vertebre. They pass from the upper edge of each vertebra to a rough
ridge on the anterior surface of the vertebra above. The ligament upon
one side is continuous with its corresponding fellow. In the cervical region
these ligaments are thinner than elsewhere, and are directed outwardly to
the inner margins of the articular processes. The interspinous ligaments
in the neck are not markedly developed, and appear like projections of
the ligamentum nuche between the spinous processes. There is no inter-
spinous ligament between the axis and atlas vertebrae, and none between
the atlas and the occipital bone. The interlaminar ligament between the
atlas and the axis, the posterior atlanto-azial ligament, and that below
the occipital bone and the atlas, the posterior occipito-atlantic ligament,
214 THE REGION OF THE NECK.

are deficient in elastic tissue, being composed chiefly of condensed areolar
tissue which is closely connected with the dura mater of the spinal cord
in front.

The nerves at the back of the neck are the posterior divisions of the '
cervical nerves.

The posterior division of the first cervical nerve, or sub-occipitai, makes
its exit from the spinal canal between the arch of the atlas and the ver-
tebral artery, and thence enters the sub-occipital triangle and sends off
muscular branches, as already described. The posterior division of the
second cervical nerve, or great occipital, emerges between the arches of
the atlas and axis vertebra. The posterior divisions of the lower six
cervical nerves divide into external and internal nerves. Of these the
internal are the larger, and those from the second, third, and fourth
nerves form the so-called posterior cervical plexus beneath the complexus
muscle, which after supplying the muscles terminate in the skin over
the trapezius. The lower three cervical nerves also give off cutaneous
branches.

There are eight pairs of cervical spinal nerves, and their origins from
the spinal cord can be seen only by removing the posterior segments of
the cervical vertebre (Plate 4, Fig. 2). The removal of these segments
exposes the theca vertebralis, or cervical portion of the spinal dura mater,
through which the spinal nerves pass out, the two roots—anterior (motor)
and posterior (sensory)—of each piercing the membrane by separate holes
and receiving from it prolongations or sheaths. The anterior roots are the
smaller, and have no ganglionic enlargement upon them, while the posterior
roots are larger, and have a ganglion upon each, with the exception some-
times of the posterior root of the first cervical nerve. The two roots of each
nerve blend with each other beyond the ganglion, and the compound trunk
thus formed passes out of the corresponding intervertebral foramen and
separates into an anterior division to supply the anterior part of the neck,
and a posterior division to supply the posterior part, each nerve being
composed of fibres from both roots. The ganglia are of oval form and
proportionate in size to the nerve-trunks to which they contribute, and
are generally situated in the intervertebral foramina outside of the dura
THE REGION OF THE NECK. 215

mater (Plate 4, Fig. 2). When the first nerve has a ganglion on its pos-
terior root, it is, however, usually within the dura.

The spinal cord presents an enlargement opposite the fifth cervical
vertebra, where the nerves are given off which form the brachial plexus
on each side. The anatomy of the spinal cord is described with the
region of the back in Vol. IT.

The vertebral arteries, after their origins from the subclavian arteries,
ascend for a short distance between the longus colli and scalenus anticus
muscles on each side, and, entering the foramen in the transverse process
of usually the sizth cervical vertebra, mount upward through the vertebral
foramina above until the interval between the axis and the atlas is reached.
Here each artery makes an abrupt curve backward, being accommodated
in grooves on the arch of the atlas vertebra within the sub-occipital
triangle, and enters the foramen magnum after perforating the posterior
occipito-atlantic ligament and the dura mater (Plate 4, Fig. 2, Nos. 9
and 25). Within the skull the two vertebral arteries unite to form the
basilar artery, which occupies the anterior median fissure of the pons
Varolii (page 46). The cervical branches of the vertebral arteries are
small, some going to the deep muscles, and others, the dateral spinal,
supplying the spinal cord and its membranes in relation to the inter-
vertebral foramina and the contiguous surfaces of the bodies of the verte-
bre. The vertebral veins commence by tributaries from the muscles in
the neighborhood of the foramen magnum, and descend in froné of the
arteries through the vertebral foramina. They are often brought in relation
_with the lateral sinus by emissary veins through the posterior condyloid
foramen on one or the other side.

The characteristic curvature of the cervical portion of the spine is
mainly due to the shape of the disks of intervertebral fibro-cartilage,
which are here thicker in front than behind. These disks, like all the
others of the spinal column, consist of outer concentric layers of fibro-
cartilage surrounding a pulpy nucleus of elastic tissue. The nucleus is
not quite in the centre of each disk, and contains a small irregular-shaped
cavity. The fibres at the circumference cross one another, taking an oblique
direction from side to side. At the margins of the disks the fibrous layers
1

ID TP ow bo

10.

24,

PLATE 3l.

The relations of the lungs, in moderate distention, to the pericardium, as in ordinary breathing. Also the great
vessels and nerves at the root of the neck. The sternum and costal cartilages are removed.

. The right superior thyroid vessels, and superior laryn-

geal nerve.

. The median notch in the thyroid cartilage.
. The right internal jugular vein.
. The right common carotid artery.

The right scalenus anticus muscle.
The median cord of the brachial plexus.

. The right pneumogastric nerve.
. The right transversalis colli artery and veins.
. The right phrenic nerve.

The brachial plexus of nerves, and subclavian artery
and vein, below the clavicle.

. The innominate artery.

. The right recurrent laryngeal nerve.

. The sternal end of the right first rib.

. The right innominate vein.

. The sternal end of the right second rib.
. The aorta, covered with the pericardium.
. The right third rib.

. The right lung.

. The right fourth rib.

. The right fifth rib.

. The right sixth rib.

. The upper surface of the diaphragm.

. The body of the hyoid bone.

The left superior thyroid vessels, and superior laryngeal
nerve. .

 

25.
26.
. The left brachial plexus of nerves, above the clavicle.
. The left phrenic nerve.

. The left scalenus anticus muscle.

. The left pneumogastric nerve.

. The left deltoid muscle.

. The left brachial plexus, below the clavicle.

. The sternal end of the left clavicle.

. The left subclavian artery and vein.

. The left pectoralis minor muscle. ‘

. The sternal end of the left first rib.

. The left innominate vein.

. The superior vena cava.

. The position of the pulmonary artery, covered with the

40.
41.
42.
43.

47,

The left internal jugular vein.
The left common carotid artery.

pericardium.

The left second rib.

The upper lobe of the left lung.

The left third rib.

The position of the right auricle, covered with the
pericardium.

. The left fourth rib.
45,
46.

The left fifth rib.

The right ventricle of the heart, covered with the peri-
cardium. :

The left sixth rib.

The left seventh rib.
ae +e

 

Copyright/890,by Georse Mc CteuAn,M.D.

ected, Photographed and Colored trom Nature by Georee Mc. Creczan, MD. ‘A

Armstron

 

 
THE REGION OF THE NECK. 217

are firmly attached to the contiguous margins of the vertebral bodies above
and below. The bodies of the vertebre and the intervertebral disks are
strongly united in front by the anterior common spinal ligament, and
by a similar band within the spinal canal, called the posterior common
ligament. The anterior ligament consists of several strata, the outer being
composed of long fibres extending along several vertebra, and the inner, of
short fibres from one vertebra to another. This ligament is thicker over
the bodies of the vertebra than the intervertebral disks, and is attached
above to the axis in connection with the longus colli muscles. Each joint
between the articular processes in the cervical vertebre is provided with a
synovial membrane surrounded with a loose capsular ligament, in accord-
ance with the free movement in the neck. For the same reason the joint
between the occipital bone and the atlas and axis vertebree has specialized
ligaments. The anterior common ligament is continued upward from the
top of the anterior arch of the atlas to the front border of the foramen
magnum, as the anterior occipito-atlantie ligament, which is thicker at the
centre than at either side. The posterior occipito-atlantic ligament has
been already referred to (page 213). If a section is made of the posterior
arches of the two upper vertebree and the occipital bone, the ligamentum
latum axiale is exposed. This is a strong fibrous band separated from the
posterior common ligament. Beneath the broad axial ligament is the
remarkably strong transverse ligament, which is stretched across between
the internal tuberosities of the atlas back of the odontoid process, a syno-
vial bursa and a thin layer of fibro-cartilage being interposed between the
process and the ligament. Some fibres of this ligament pass upward from
its centre to be attached to the basilar process, and some downward to the
body of the axis. The occipito-odontoid or check lgaments are placed
above the transverse ligament, and extend from the inside of each occipital
condyle to the same side of the top of the odontoid process. They are
rendered tense by turning the head to one side or the other. A few
fibro-cartilaginous fibres pass from the apex of the odontoid process te
the front of the foramen magnum, and are called the suspensory ligament
of the avis. In addition to the above, the articular surfaces of the occiput

and atlas are provided with synovial sacs and capsular ligaments. The
28
218 THE REGION OF THE NECK.

cervical curve of the spine is considered as consequent upon the exten-
sion of the neck in development, and extends from the atlas to the inter-
vertebral disk between the second and third dorsal vertebrae. The weakest
point, not only in the neck but also in the entire column, is between the
second and third cervical vertebre.

The structures in immediate relation to the front of the cervical
portion of the spinal column are the prevertebral muscles and fascia
(Plate 11, Fig. 1). The longus colli muscle consists principally of a
vertical portion, the fibres of which arise tendinously from the lateral
ridges on the bodies of the three upper dorsal and two lower cervical
vertebree external to the common spinous ligament, and are inserted by
arching tendons into the bodies of the fourth, third, and second cervical
vertebree, and into the anterior tubercle of the atlas. Besides these there
are accessory portions. The inferior oblique portion arises with the vertical
tendons from the three upper. dorsal vertebra, and is inserted into the
transverse processes of the sixth, fifth, and fourth cervical vertebre.
Those fibres which are inserted into the sixth vertebra cover the verte-
bral artery at its entrance into the foramen in the transverse process of
that vertebra. The superior oblique portion arises from the transverse
processes of the fifth, fourth, third, and sometimes second cervical verte-
bree, and is inserted with the vertical portion into the bodies of the upper
two vertebree and the anterior arch of the atlas. The longus colli muscle
is supplied by branches from the lower cervical nerves, and the action of
the united portions is to bend the cervical vertebre forward.

The rectus capitis anticus major muscle arises from the transverse
processes of the fifth, fourth, third, and second cervical vertebre, and is
inserted into the basilar portion of the occipital bone near the pharyngeal
spine. Under this muscle there is a much smaller muscle, the rectus capitis
anticus minor, which arises from the front of the root of the transverse
process of the atlas, and is inserted into the basilar process of the occipital
bone behind the former muscle. The two recti antici are supplied with
branches of the anterior division of the sub-occipital nerve, and some
filaments from the deep cervical plexus, and their action is to assist in
bending the head forward. The rectus capitis lateralis muscle extends
THE REGION OF THE NECK. 219

from the transverse process of the atlas to the jugular process of the
occipital bone, and is in reality the topmost of the series of inter-
transversales muscles in the cervical region, which extend between the
successive transverse processes in front of the exits of the spinal nerves
and over the vertebral artery. The laterales are capable of bending the
head slightly sideways.

The cervical portion of the sympathetic nerve on each side consists of
a continuous cord, on which there are three ganglia, situated in front of
the transverse processes of the cervical vertebree. The superior ganglion
is the largest of the three, and is about opposite the second and third
cervical vertebree, over the rectus capitis anticus major muscle, behind
the internal carotid artery, and internal to the pneumogastric nerve
(Plate 36, No. 49). It is an elongated, reddish-gray body, generally
three centimetres, or about an inch and a quarter, in length. It is some-
times marked by constrictions, and receives externally four communi-
cating branches from the four upper cervical nerves. It sends branches
to the upper and lower ganglia of the pneumogastric (page 204), also to the
ganglion of Andersch, on the glosso-pharyngeal nerve (page 205), and to
the hypoglossal nerve. From the upper portion of the superior ganglion
the cord is continued into the carotid canal with the internal carotid artery,
to form the carotid sympathetic plexus. Filaments leave the anterior
border of the superior ganglion and accompany the branches of the external
carotid artery, upon which they form plexuses and are distributed to the
territories which they supply. A branch is also sent to the inter-carotic
body. The superior cardiac nerve arises from the lower part of the supe-
rior ganglion, and descends upon the longus colli muscle behind the sheath
of the carotid vessels, in close connection with the main sympathetic cord.

The middle cervical ganglion is very small and inconstant, and when
present is situated opposite the sixth cervical vertebra, near the inferior
thyroid artery, and about on a level with the crossing of the omo-hyoid
muscle. It receives branches from the adjacent cervical nerves, and gives
off thyroid branches and the middle cardiac nerve, which descends with
the superior cardiac either over or under the subclavian artery to join the
cardiac plexus.
220 THE REGION OF THE NECK.

The inferior cervical ganghon is deeply situated between the transverse
process of the vertebra prominens and the neck of the first rib (Plate 36,
No. 22). It receives branches from the seventh and eighth cervical nerves,
and gives off branches which form the plexuses about the subclavian and
vertebral arteries and the inferior cardiac nerve, which joins the deep
cardiac plexus.

The scalene muscles extend from the transverse processes of the cervical
vertebree to the two upper ribs, in the manner of a scalene triangle, on each
side, and are comparable to the intercostal muscles both in their attach-
ment and in their function. The scalenus anticus arises from the anterior
tubercles of the transverse processes of the third, fourth, fifth, and sixth
cervical vertebre, and is inserted by a flat tendon at the inner border and .-
upper surface of the first rib (Plates 31, 32, 34, 35, and 36). This muscle
is usually described as being inserted into the tubercle (of Lisfranc) on
the first rib, and much stress has been laid upon it as an important guide
to the adjacent vessels; but, after examining several hundred specimens,
the author has the recollection of seeing only four or five upon which
any approach to a tubercle was developed. The scalenus medius arises
from the postercor tubercles of the transverse processes of the lower six
cervical vertebra, and is inserted also upon the first rib behind the scalenus
anticus. This is the strongest of the three scalene muscles. The scalenus
posticus arises from the posterior tubercles of the transverse processes of
the three lowest cervical vertebra, and is inserted upon the second rib
external to its angle. These muscles receive their nerves from the lower
cervical nerves, which they surround as they leave their grooves on the
upper surfaces of the transverse processes. Their combined action is to
raise the thorax, as in deep inspiration, or, being fixed below, they can
bend the eervical vertebree, as in rising from the recumbent position.
The scalenus anticus is a guide in distinguishing the position of the im-
portant structures with which it is in close relation at the root of the neck.
The lower attachment of the scalenus anticus is usually overlapped by
the clavicular portion of the sterno-mastoid muscle, but by depressing the
shoulder and extending the neck the outer border of the former muscle
can be readily felt.
THE REGION OF THE NECK. 221

The subclavian artery and the subclavian vein are separated by the
costal attachment of the scalenus anticus, as.they pass in their respective
grooves upon the first rib on their way to and from the axilla. The vein
is in front and the artery is behind: the latter can sometimes be felt
pulsating over the rib by pressing with the thumb in the supra-clavicular
fossa, at the outer border of the sterno-mastoid muscle. In this way
also compression of the subclavian artery may be sometimes satisfactorily
effected, as is required in amputation at the shoulder. In one instance
the author found both the artery and the vein in front of the scalenus
anticus; and several cases have been recorded in which the relations of
the vessels were reversed, the artery being in front of the vein.

In relation to the scalenus anticus muscle it should be remembered that
the phrenic nerve (page 207) passes obliquely from the outer to the inner
border in front of that muscle, to enter the chest between the subclavian
artery and subclavian vein (Plates 25 and 31), and that it is joined on
the outer surface of the muscle by a twig from the fifth branch of the
cervical plexus as well as by a filament from the sympathetic nerve.

The supra-scapular and transversalis colli arteries (page 233) cross
over the lower part of the scalenus anticus, and between it and the sca-
lenus medius and above the subclavian artery are the cords of the brachial
plexus of nerves. Its inner border is in close relation with the vertebral
artery, which is here covered by the internal jugular vein.

The structures collected at the root of the neck (Plate 14, Fig. 2)
present a complex arrangement which varies upon both sides, even in the
normal condition, in consequence of the mode of distribution of the great
aortic branches. The innominate artery upon the right side leaves the
aorta at the commencement of the transverse portion of the arch behind
the middle of the manubrium sterni, opposite the fourth dorsal vertebra,
and ascends to the sterno-clavicular joint, behind which it subdivides into
the right subclavian and right common carotid arteries. The innominate
artery is usually four centimetres, or about an inch and a half, in length,
in a well-developed adult, but it is often half an inch longer, and in some
cases the vessel ascends above the clavicle close to the trachea before it
divides. The innominate sometimes gives off a branch, the thyroidea ima
222 THE REGION OF THE NEOK.

(Plate 43), which ascends to the lower border of the thyroid body along
the front of the trachea and. compensates for a deficiency in the inferior
thyroid artery. In the child, owing to the greater laxity of the connective
tissue and the prolongation of the cervical fascia, the innominate artery may
be drawn upward into the supra-sternal notch by extending the head and
neck backward, but this cannot be done in the adult if the artery is in its
normal position. It has been demonstrated on the dead subject (Burns) that
if the innominate artery be tied with a ligature the collateral circulation can
be established both in the right side of the head and in the right arm, and
the operation has been successfully performed on the living subject (Mott) ;
but it is a desperate undertaking, and should not be attempted except as
such. The artery lies above the bifurcation of the trachea, and is enveloped
in a strong sheath prolonged from the deep cervical fascia, which continues
over it to the pericardium. The two vene innominate, or right and left
brachio-cephalic veins, converge in front of the innominate artery to empty
into. the superior vena cava, the right vein descending on the outer side
of the artery and the left vein passing across its origin. These veins thus
form a triangular space (Plates 31 and 35), in which the artery appears
when the loose fascia which connects it to the coat of the deft innominate
vein is removed.

The pneumogastric nerve descends into the thorax between the right
innominate vein and the innominate artery at its bifurcation into the
right subclavian and common carotid arteries, and in this relation gives
off the right recurrent laryngeal nerve, which turns upward under the
subclavian or innominate artery, as previously described (page 186). It
will be noticed that the great innominate veins, with all their tributaries,
occupy a plane anterior to that of their respective arteries, which is the
converse of the relation of the arteries and veins below the diaphragm
(Plate 42), with the single exception of the renal vein. The innominate
veins are formed respectively by the confluence of the common jugular and
subclavian veins of each side. The right vein commences behind the right
sterno-clavicular joint, and descends a little forward to a point opposite the
first right intercostal space, where it is joined at an obtuse angle by the
left vein, to empty into the superior vena cava. It is about two and a
THE REGION OF THE NECK. 223

half centimetres, or an inch, in length, and receives the right internal
mammary, superior intercostal, and inferior thyroid veins. The left
innominate vein is nearly three times the length of the right, being six
centimetres, or two and a half inches, as it commences behind the sternal
end of the left clavicle and extends across the origins of the left common
carotid and innominate arteries. The left vein receives upon its under
surface the left internal mammary, thymic, and mediastinal veins, and
on its upper surface the left inferior thyroid, vertebral, and deep cervical
veins. The tributary veins to both vessels are guarded with single
crescentic valves at their orifices. In the young child the left innomi-
nate vein is generally above the upper margin of the sternum. Between
the innominate vessels and the sternum there is a considerable quantity
of adipose and connective tissue, and in the adult the remains of the
thymus gland (and in the child, up to the third or fourth year, the gland
itself), with numerous veins. These veins form a plexiform net-work, and
are associated with the inferior thyroid veins, which occupy the space be-
tween the trachea and the top of the sternum and empty into the right and
left innominate veins. The presence and proximity of these veins render
any operation in this locality extremely hazardous. They are liable to
become dilated and engorged from interference with the respiration, as in
membranous croup, or under the influence of pressure from a neighboring
growth. In a patient from whom the author successfully removed the
upper portion of the sternum and adjacent third of the clavicle for osteo-
sarcoma, the venous hemorrhage was appalling, and could be arrested only
by sponge pressure.

The right and left common carotid arteries ascend from the root of the
neck by the sides of the trachea, diverging outward from the middle line
to their bifurcation opposite the top of the thyroid cartilage (page 201).
On a level with the top of the sternum, and three centimetres, or about an
inch and a quarter, from the surface, the two carotid arteries are separated
from each other by two centimetres, or less than an inch, but at their bifur-
cation, owing to the breadth of the larynx, they are six centimetres, or two
and a half inches, apart (Plates 31, 32, 33, and 42). In consequence of
the independent thoracic origin of the left common carotid artery from the
COoOms noah WD

rad

to
on

S

PLATE 32:

The relations of the lungs, partially distended (as in tranquil respiration), to the pericardium. Also the vessels and
nerves at the root of the neck.

. The right facial artery.

. The right facial vein.

. The right lingual artery.

. The right thyro-hyoid artery.

. The right superior laryngeal nerve.

. The right external carotid artery.

. The thyroid notch.

. The thyroid cartilage.

. The right superior thyroid artery.

. The right superior thyroid vein.

. The right common carotid artery.

. The right scalenus anticus muscle.

. The right trapezius muscle.

. The right internal jugular vein.

. The right brachial plexus of nerves.

. The right pneumogastric nerve.

. The right phrenic nerve.

. The supra-scapular artery and veins,

. The right recurrent laryngeal nerve. .

. The right deltoid muscle.

. The brachial plexus of nerves below the clavicle.
. The right axillary artery.

. The right axillary vein.

. The right innomiuate vein.

. The sternal end of the right first rib.

. The superior vena cava.

. The right phrenic nerve.

. The sternal end of the right second rib.

. The upper lobe of the right lung.

. The right auricle covered with the pericardium.
. The sternal end of the right third rib.

. The middle lohe of the right lung.

33.
. The height to which the diaphragm arches on the

The sternal end of the right fourth rib.

right side.

. The sternal end of the right fifth rib.
. The lower lobe of the right lung.
. The sternal end of the right sixth rib.

 

38.

39.
40.
41,
42,
43,
44,
45.
46.
47,
48.
49,
50.

51.
. The left deltoid muscle.

. The trachea.

. The left common carotid artery.

. The left axillary vein. :

. The innominate artery.

. The left innominate vein.

. The sternal end of the left first rib.

. The long thoracic artery.

. The pectoralis minor muscle.

. The left phrenic nerve. ;

. The root of the heart covered with the pericardium.

. The sternal end of the left second rib.

. The upper lobe of the left lung.

. The sternal end of the left third rib.

. The sternal end of the left fourth rib.

. The right ventricle of the heart covered with the peri-

The branches of the right phrenic nerve on the dia-
phragm.

The left facial artery.

The left facial vein.

The left thyro-hyoid artery.

The left external carotid artery.

The left internal jugular vein.

The left superior thyroid artery.

The left trapezius muscle.

The left crico-thyroid artery.

The cricoid cartilage.

The left brachial plexus of nerves.

The left phrenic nerve.

The left scalenus anticus muscle.

The left pneumogastric nerve.

cardium.
The sternal end of the left fifth rib.

. The sternal end of the left sixth rib.
. The branches of the left phrenic nerve on the dia-

phragm.

. The sternal end of the left seventh rib,
 

 

 

oy Georce M.

Cretan, M OD.

 

 

ent /BO/ by Geor6eEMcCLeLLA

 
THE REGION OF THE NECK. 225

arch of the aorta, it is longer than the right, the thoracic portion being
equivalent in length to the innominate artery. The thoracic portion of
the left common carotid artery is crossed by the left innominate vein, and
its under surface is in relation to the trachea, cesophagus, and thoracic
duct (Plate 39).

In the neck, between the clavicle and the position of the crossing of the
omo-hyoid muscle the relations of the two carotids are almost identical.
The right artery is usually a little nearer the surface than the left, and its
calibre is larger. The right and left common jugular veins occupy separate
compartments of the general sheaths on the outer sides of their companion
arteries. As they approach their termination in the innominate veins they
overlap the arteries, and on the left side this is more especially so than on
the right (Plates 83 and 42), because of the inclination of the large veins
from the left to the right side to reach the venous side of the heart. The
calibre of the right common jugular usually exceeds that of the left, and
they are both provided with double valves about three centimetres, or an
inch and a quarter, above their terminations.

The right and left pnewmogastric nerves ascend also in separate com-
partments of the sheath posterior to the septa between the artery and the
vein, but somewhat nearer the latter. The position of the carotid vessels,
on each side, may be indicated by drawing a line from the top of the
sternal end of the clavicle to the parotid gland between the mastoid process
and the angle of the lower jaw. As the sterno-mastoid muscle is attached
to the anterior surface of the top of the sternum, with its fibres interlacing
with those of the sternal portion of its fellow muscle (Plates 23 and 24),
it completely covers the line of the carotid vessels, which in reality corre-
sponds to the space between the sternal and clavicular attachments of the
sterno-mastoid muscle (page 197). Between the sheath of the vessels
and the sterno-mastoid muscles at the root of the neck there are also
the sternal attachments of the sterno-hyoid and sterno-thyroid muscles,
and between the latter muscles and the sheath are the intricate thyroid
veins, and sometimes the external jugular vein passing into the internal
jugular to empty conjointly into the subclavian (Plate 21).

The sheath of the carotid vessels is separated posteriorly from the bodies
29
226 THE REGION OF THE NECK.

of the lower cervical vertebree by the longus colli and rectus capitus anticus
muscles. It is in close relation with the sympathetic nerve cord, and
separated from the vertebral artery by the inferior thyroid artery, which
winds upward and inward from the subclavian to the thyroid body. To
the inner side are the trachea, the larynx, and a lobe of the thyroid body.
The cesophagus inclines to the left of the middle line at the root of the
neck, so that it is in closer relation to the left carotid sheath. The recurrent
laryngeal nerve on both sides ascends to the larynx between the trachea
and the cesophagus, but is separated from the carotid sheath by considerable
cellular tissue (Plate 24, Fig. 2).

In the operation for applying a ligature upon the carotid artery it is
essential to avoid as far as possible interfering with the cellular investment
of the sheath and its attachment to the reflections of the deep cervical
fascia (page 195). In order to reach the artery the head should be turned
to the opposite side over a pillow, so as to bring into relief the anterior
border of the sterno-mastoid muscle, along which an incision from three
to four inches in length should be made through the skin, superficial
fascia, and platysma muscle so as to intersect the line of crossing of the
omo-hyoid muscle at the level of the cricoid cartilage. The carotid sheath
is immediately under the omo-hyoid, and this muscle may be cut through,
or the sheath can be opened above or below it as required. A finger
pressed upon the vein at the root of the neck will cause it to distend
and reveal its. precise relation. The sheath should be opened on the
tracheal side, and it is well to raise the head and to turn it to the same
side before passing the artery needle, so as to relax the tissues and avoid
including or injuring any of the adjacent structures. The descendens
hypoglossi nerve is usually seen upon the sheath, and the sterno-mastoid
branch from the superior thyroid artery crosses it near the omo-hyoid
muscle. The thyroid veins are numerous over the sheath at the root of
the neck; and if it is necessary to tie the artery in that locality, they
must first be secured with a double ligature and severed. Upon the left
side the operation low down is attended with so much difficulty that it is
well to divide the sternal attachment of the sterno-mastoid muscle, which
will render the vessel more accessible.
THE REGION OF THE NEOK. 227

After ligation of the common carotid artery the collateral circulation
is established through the anastomoses of the branches of the external and
internal carotid arteries of the opposite side with the branches of the
ligatured side, in which the blood-current is reversed, and between the
vertebral and posterior communicating, the inferior and superior thyroids,
and the profunda and princeps cervicis, of the same side.

The deep cervical lymphatic glands (or glandule concatenate) form a
chain extending from the base of the skull to the root of the neck em-
bedded in the connective tissue which surrounds the great vessels. Some
of these glands are directly over the sheath of the common carotid, and |
others lie between it and the bodies of the cervical vertebre, so that when
they become diseased they are often so adherent to the adjoining struc-
tures that their removal is extremely hazardous. These glands are con-
tinuous with the thoracic and axillary glands. They are most numerous
in the neighborhood of the bifurcation of the common carotid artery by
the side of the pharynx, as they receive here the lymphatic vessels from
all parts of the head and neck. The cervical lymphatic vessels unite at
the inner border of the scalenus anticus muscle on both sides, so as to
form the jugular lymphatic trunks. Upon the right side the trunk empties
into the right lymphatic duct, which is about twelve millimetres, or half
an inch, in length, and terminates at the junction of the common jugular
and subclavian veins, and on the deft side the trunk generally empties
into the thoracic duct (page 318), and sometimes, by a separate orifice,
directly into the angle of junction of the left common jugular and sub-
clavian veins (Plate 20).

The subclavian arteries differ not only in their origins but in their
relations upon the two sides of the root of the neck (Plates 33, 35, and 39).
Each of them pursues an arching course to pass behind the scalenus anticus
muscle (page 221), which divides the vessel into three portions,—the first
or pectoral portion being between its origin and the inner border of the
scalenus anticus, the second or muscular portion that which is behind it,
and the third or cervical portion that which is between the outer border
of the muscle and the lower border of the first rib, whence the artery
continues as the axillary.
228 THE REGION OF THE NECK.

The right subclavian artery ordinarily leaves the innominate behind
the sterno-clavicular joint, and its first portion is very deeply placed as it.
passes upward and outward to the inner border of the scalenus anticus.
Any change in the position of the bifurcation of the innominate artery
will of course affect the point of origin of this artery. Besides the
superficial coverings, it has over it the insertions of the presternal muscles
(Plate 23) and a layer of deep fascia which is projected from the inner
- border of the scalenus anticus muscle. Under this fascia it is crossed
by the common jugular and vertebral veins (Plate 21), by the pneu-
mogastric and phrenic nerves (Plates 34 and 35), and by the superior
cardiac sympathetic nerves. Behind the artery are the recurrent and
sympathetic nerves (Plate 36) upon the longus colli muscle and the
transverse process of the first dorsal vertebra. It is here, also, in close
proximity to the apex of the right lung covered with its pleura (Plate 39).
The subclavian vein lies below the artery, under cover of the clavicle.
Three branches are given off from the first portion of the subclavian
artery,—.¢., from its under surface the internal mammary (page 257), and
from its upper surface the vertebral (page 232) and the thyroid axis
(page 232). .

The left subclavian artery commences within the thorax by an inde-
pendent origin from the arch of the aorta, and its first portion is conse-
quently longer than that of the right. Its calibre is less, and it is also
deeper. Within the thorax the first portion is crowded by the apex of the
left lung within its pleura. It is covered by the sternal end of the first
rib, by the sterno-clavicular joint, and by. the left subclavian vein on its
way to join the jugular vein to form the left innominate vein. Between
- the vein and the artery in this locality the phrenic nerve descends. Be-
hind the artery, and internal to it, are the trachea, the cesophagus, the
left recurrent laryngeal nerve, the inferior cervical ganglion of the sympa-
thetic, and the thoracic duct (Plates 86 and 39).

Above the clavicle the first portion of the left subclavian artery corre-
sponds very nearly in its relations to those on the right side, and its
branches are similarly disposed. The second portions of both the right
and left arteries very closely resemble each other as they pass between the
THE REGION OF THE NECK. 229

scalenus anticus and scalenus medius muscles over the first rib, the only
difference being in the height to which the artery ascends above the
clavicle, which in some cases is as high as four centimetres, or an inch
and a half. The right subclavian usually arches higher than the left
(Plate 35). The phrenic nerve descends across the scalenus anticus
muscle, and at its anterior border passes between the artery and the
vein. The superior intercostal artery is the only branch given off from
the subclavian behind the scalenus anticus.

The third portions of both subclavian arteries also resemble each other
in their relations. Here the vessel is more superficial as it passes downward
over the first rib. It occupies the supra-clavicular triangle, formed by the
sterno-mastoid and omo-hyoid muscles and the clavicle; but it should
be remembered that the dimensions of this triangle may be encroached
upon by the approximation of the sterno-mastoid and trapezius muscles
(page 207). As this portion of the artery is most readily exposed, and
therefore most easily ligatured, it deserves special attention. Besides the
superficial coverings in this locality, there is the double layer of deep
fascia, consisting of the expansion from the omo-hyoid to the clavicle
and the underlying expansion from the scalenus anticus. Within the
superficial fascia the supra-clavicular nerves, the lower end of the external
jugular vein, and the transverse cervical and supra-scapular veins cross
this space (Plates 18 and 19). In the ordinary position of the arm the
clavicle and subclavius muscle and the supra-scapular vessels lie directly
over this portion of the subclavian artery, but by turning the head and
neck to the opposite side and depressing the shoulder the axillary artery
may be drawn upward and made to take its place. The artery rests
directly in a groove upon the firsi rib, and the outer border of the .
scalenus anticus muscle is a direct guide to it (page 220). The sub-
clavian vein is below and on a plane anterior to it, under cover of the
clavicle. The cords of the brachial plexus of nerves and the posterior
portion of the omo-hyoid muscle are placed obliquely above the artery.
The supra-scapular artery usually arises from the third portion of the
subclavian, although occasionally it is derived from the thyroid axis at
the inner border of the scalenus anticus muscle.
1.
2.
3.
4,
5:
6.
7.
8.

9.
10.
1.
12,
13.
14.

15.
16.
17.

18.
19.
20.
21.
22,
23.
24,
25.
26.
27,
28,

PLATE 88.

The relations of the lungs, when completely collapsed, to the heart. Also the deeper relations of the vessels and
nerves at the root of the neck. The pericardium is removed, and the ribs sawn through at their middle to give a better
view into the cavity of the thorax. The clavicles are also removed.

The right facial artery and vein.
The right digastric muscle.

The right lingual artery.

The right superior laryngeal nerve.

. The right superior thyroid artery.

The right common carotid artery.

The right internal jugular vein.

The right pneumogastric nerve.

The right phrenic nerve.

The right brachial plexus of nerves.

The right scalenus anticus muscle.

The right supra-scapular artery and veins.

The right subclavian artery.

The origin of the subclavian artery from the innomi-
nate artery.

The right subclavian vein.

The innominate artery.

The right recurrent laryngeal nerve, winding under
the innominate artery.

The right innominate vein.

The back of the upper part of the thoracic cavity.

The superior vena cava.

The right phrenic nerve.

The ascending portion of the aorta,

The upper lobe of the right lung.

The right auricle of the heart.

The middle lobe of the right lung.

The position of the tricuspid valve.

The lower lobe of the right lung.

The branches of the right phrenic nerve on the upper
surface of the diaphragm.

 

29.
30.
31.
32,
. The thyro-hyoid membrane.

The diaphragm.

The left facial artery and vein.
The left digastric muscle.

The body of the hyoid bone.

The thyroid notch.

. The left superior laryngeal nerve.
. The left superior thyroid vein and artery.
. The crico-thyroid membrane, and the crico-thyroid

artery.

. The cricoid cartilage.

. The left internal jugular vein.

. The left common carotid artery.

. The left recurrent laryngeal nerve.

. The left scalenus anticus muscle.

. The left brachial plexus of nerves.

. The left subclavian artery.

. The left subclavian vein.

. The left innominate vein.

. The left pneumogastric nerve giving off its recurrent

branch to pass under the aorta.

. The back of the upper part of the thoracic cavity.

. The transverse portion of the arch of the aorta.

. The left phrenic nerve.

. The pulmonary artery.

. The upper lobe of the left lung.

. The right ventricle of the heart.

. The lower lobe of the left lung.

. The branches of the left phrenic nerve on the upper

surface of the diaphragm.
At iC

 

 

/§9/b M-

Copynght/oF/by GEORGE!)

CreccanMD.

Armstrong & Co. Lith Boston.

1 Colored’ From Nature oy Georce Mc. Cretan, MD,

Dissected, Photograzhed and Colored trom Nature
THE REGION OF THE NECK. 231

The subclavian vein, upon either side, does not arch upward like its
companion artery, but takes nearly a straight course to join with the
common jugular in forming the corresponding innominate vein. It ex-
tends from the lower border of the first rib to a point between the
insertion of the scalenus anticus and the sterno-clavicular joint. The
phrenic and pneumogastric nerves descend between it and the artery upon
both sides of the neck, and it receives its blood through the anterior and
external jugular veins. Before its junction with the common jugular it
is guarded with a pair of valves. It should be noted that throughout its
course the subclavian vein is placed on a lower plane than, and in front
of, the artery. The sheath over the subclavian vessels is attached to the
back of the clavicle, and, as the vein is more firmly enveloped by it than
the artery, it follows the movements of that bone. This intimate relation
of the vein to the clavicle renders it liable to injury in fractures of that
bone. The operation for tying the subclavian artery is a difficult task,
even upon the dead subject with the parts in their normal positions. It is
naturally more so upon the living, and not only is a practical knowledge
of the anatomy requisite, but also a knowledge of the possible deviations
which attend the structural changes in consequence of aneurism or other
tumor involving this region.

In ligation of the subclavian artery in the third or outer part of its
course the patient’s head should be turned back, the shoulders raised,
and the arm pulled down to the utmost, so as to lower the clavicle. The
integument should be drawn downward, and an incision several inches
long should be made directly upon the clavicle through the superficial
coverings. If the trapezius and sterno-mastoid muscles overlap the supra-
clavicular space they must be cut and turned aside. In this incision care
must be taken not to wound the external jugular vein, and, as the supra-
scapular veins are often in the way, they may require a double ligature and
section. The deep fascia can be opened by following the external jugular
vein as it pierces it. Much time is often lost through mistaking the cellular
space above the deep fascia for that below it. In the depths of the latter
the artery in question is situated. In more than one instance the lower
cord of the brachial plexus has been mistaken for the artery, and on several
232 THE REGION OF THE NECK.

occasions tied; but this is not likely to happen if before securing the liga-
ture the arm is raised and rotated, so as to relax the parts, when they can
be better recognized. The impression conveyed to the finger by pressing
over the first rib should never be relied on. The operator does not usually
see the vein. It is out of the way, below the clavicle. In the deeper
cellular space there is generally a quantity of fat, with some lymphatic
glands, which when enlarged offer additional embarrassment to the opera-
tion. The collateral circulation after the artery has been tied in its
outer portion is maintained by the occluded branches of the axillary
artery drawing the blood from their anastomoses with the superior inter-
costal, upper aortic, intercostal, and internal mammary arteries, assisted by
the communications between the dorsalis scapule and the supra-scapular
and posterior scapular arteries.

The vertebral artery arises from the upper and posterior surface of the
first portion of the subclavian. It ascends behind the common jugular |
vein, and runs between the scalenus anticus and longus colli muscles until
it enters the vertebral foramen in the transverse process of the siath
cervical vertebra. On the way it is crossed by the inferior thyroid
artery, and on the Jdefé side by the thoracic duct. The sympathetic nerve
cord is in close relation to it, and some delicate nerves from the inferior
cervical ganglion pass along with it, and others pass across, to blend with
the cords of the brachial plexus. After entering the transverse process of
the sixth vertebra it continues up through the corresponding foramina in
the transverse processes of the vertebree above until it arrives at the atlas
in the sub-occipital triangle (Plate 4, Fig. 2), where, after it rises through
the foramen in the transverse process, it turns backward round the condyle
of the occipital bone to penetrate the posterior occipito-atlantic ligament
and to enter the sub-dural space within the foramen magnum. Within
the cranium the vertebral artery passes between the hypoglossal nerve
and the anterior root of the first cervical nerve and ascends upon the
basilar process to join with its fellow (page 22) and form the basilar
artery (Plate 5, Fig. 3).

The thyroid axis is a short trunk arising from the first portion of the
subclavian at the inner border of the scalenus anticus muscle. It usually
THE REGION OF THE NECK. 233

divides into three branches, the inferior thyroid, the transversalis colli, and
the supra-scapular. The inferior thyroid artery ascends tortuously across
the vertebral artery, the recurrent laryngeal nerve, and the longus colli
muscle to the corresponding lobe of the thyroid body. The middle cervical
ganglion of the sympathetic nerve is very close to it as it passes beneath
the sheath of the carotid vessels. The inferior thyroid sends off branches
to the pharynx, cesophagus, trachea, and the anterior mediastinal glands,
and the little inferior laryngeal artery which accompanies the recurrent
laryngeal nerve. Within the thyroid body it breaks up into terminal
branches which anastomose freely with those of the other thyroid
arteries. The ¢ransversalis colli artery usually arises from the axis
and passes over the scalene muscles and the brachial plexus to reach
the upper angle of the scapula, where it supplies the adjacent muscles.
Its veins are in close relation with it and empty their blood into the
external jugular. The transversalis colli often gives off the superficial
cervical artery, which passes upward along the border of the trapezius
muscle (Plate 25) and anastomoses with the descending branch of the
occipital artery. It is accompanied by two vene comites, which join the
transverse veins. The supra-scapular artery arises sometimes from the
thyroid axis, sometimes independently from the third portion of the sub-
clavian artery (page 229). It passes behind the clavicle, separated from
the subclavian artery by the reflection of the deep cervical fascia from
the omo-hyoid muscle, and on reaching the scapula it enters the supra-
spinous fossa. It then passes over the supra-scapular ligament and
eventually terminates in the infra-spinous fossa. In its course it sends
branches to the neighboring muscles, to the clavicle, to the acromion and
body of the scapula, and to the shoulder-joint. This vessel is accompa-
nied by two veins, which are provided with valves at their termination
in the external jugular or subclavian veins.

The thyroid body is the very vascular glandular organ which is
situated in the neck over the front and sides of the upper part of the
trachea, extending upward on each side of the larynx. It consists of two
ovoid lateral lobes, united near their lower borders by a median transverse

portion, the isthmus. It is of a reddish-brown color, and weighs in the
30
234 THE REGION OF THE NECK.

adult about two ounces. Each lobe extends from the fifth or sixth ring
of the trachea below to the side of the thyroid cartilage above, which is
embraced by the narrower end. Lach lobe is five centimetres, or about
two inches, in length, by three centimetres, or an inch and a quarter, in
breadth. The anterior surface is convex, and covered by the infra-hyoid,
sterno-hyoid, sterno-thyroid, and omo-hyoid muscles (Plates 23, 24, and
25), and is overlapped at the sides by the anterior borders of the sterno-
mastoid muscles. The posterior surface is adapted to and closely adherent
to the parts of the trachea, larynx, and cesophagus over which it lies.
The carotid sheath is usually in contact with the external border of the
lobe on each side, but very often it is embraced, particularly on the right
side, by the glandular structure.

The isthmus is variable in size, shape, and position, and usually crosses
over the second and third rings of the trachea, being firmly attached by a
band of the deep cervical fascia, besides the general investment which con-
nects the thyroid body to the sides of the trachea and to the cricoid and
thyroid cartilages. In consequence of this intimate association the organ
rises and falls with the larynx in swallowing, and thus a valuable means
is afforded of distinguishing the character of any enlargement of its lobes.
Very often there is an accessory pyramidal middle lobe which extends
upward from the junction of the isthmus with the left lobe to be attached
to the thyro-hyoid membrane by a fascial band. This may sometimes be
covered by a separate slip from the sterno-hyoid muscle, called the levator
corporis thyroider.

The thyroid body varies in size in different individuals and at different
periods of life. It is relatively larger in the child than in the adult, and
in the female than in the male. In children the isthmus is usually very
insignificant. The function of the thyroid body is unknown, but it is
supposed to be in some way a blood-forming organ and to regulate the
production of mucin. Each lobe consists of many irregular lobules, held
together by areolar-tissue septa which are inflected from the external
glandular investment. In these septa are the branchings of the vessels,
surrounded not unfrequently with a colloid substance. The lobules are
composed of a great number of closed follicles, the epithelial lining of
THE REGION OF THE NECK. 235

which secretes a serous fluid in the child. In the adult the lining wall
degenerates and colloid matter takes the place of the earlier limpid fluid.
There are fine sympathetic nerve filaments which accompany the vessels
throughout the glandular structure; and there are numerous lymphatic
vessels which commence in lymph-spaces in the interlobular septa and
terminate in the lymphatic ducts upon each side of the neck. There is
no proper duct to the thyroid body itself. The arteries which supply the
thyroid body are remarkable for their number, size, and free inoscula-
tion. The superior thyroid arteries (page 203) arise from the external
carotid arteries just below the greater cornua of the thyroid cartilage, and
curve downward beneath the infra-hyoid muscles to the upper and front
surface of the thyroid body (Plate 24). The inferior thyroid arteries arise
from the thyroid axis of the subclavian arteries (page 233) and ascend
tortuously to the under surface of the thyroid body. Occasionally there is
a middle thyroid artery, the thyroidea ima, which arises either from the
arch of the aorta or from the innominate artery and ascends in front of
the trachea to the isthmus. The ¢hyroid veins are also remarkably large,
and form a plexus upon the lobes of the thyroid body. The superior and
middle thyroid veins upon each side empty into the internal jugular. The
inferior thyroid veins communicate freely with each other over the trachea
in the anterior part of the root of the neck, and terminate in the innomi-
nate veins. The relations of the thyroid body to the great vessels and
nerves of the neck explain many of the symptoms produced by the hyper-
trophied condition of any portion of it, known as “ bronchocele.”

The trachea in the neck is covered anteriorly by the sterno-hyoid and
sterno-thyroid muscles (Plate 23, Fig. 2). The sterno-hyoid muscles are
thin fleshy bands of parallel fibres beneath the skin, which arise on each
side from the posterior surface of the sterno-clavicular joint and the con-
tiguous portions of the clavicle and manubrium sterni. They ascend and
converge to be inserted tendinously into the lower border of the body of
the hyoid bone. The sterno-thyroid muscles arise from the posterior surface
of the manubrium sterni, internal to the sterno-hyoid muscles, and from
the cartilage of the first rib on each side, and ascend like two muscular
ribbons, diverging a little from each other to be inserted into the oblique
236 THE REGION OF THE NECK.

lines of the ale of the thyroid cartilage. Occasionally these muscles
present tendinous intersections. The thyro-hyoid muscles are continu-
ations upward of the sterno-thyroid muscles, and are variable in their
degree of separation from them. They are somewhat broader than the
sterno-hyoid, and project laterally beneath the attachments of the omo-
hyoid muscles. These muscles are all brought into action in forced
inspiration. The sterno-hyoid aids the omo-hyoid in depressing the hyoid
bone. The thyro-hyoid elevates the thyroid cartilage, while it is depressed
by the sterno-thyroid. These muscles are innervated by the communi-
cating loop from the descendens hypoglossi nerve (Plate 27). In the
middle line the fascial sheaths of the sterno-thyroid and sterno-hyoid
muscles blend and form the linea alba cervicalis, which can ‘be readily
distinguished after incision through the integument (Plate 23.)

The trachea is the cartilaginous and membranous portion of the
windpipe which commences at the cricoid cartilage of the larynx opposite
the fifth cervical vertebra (page 177) and extends medially downward
to about the body of the fourth dorsal vertebra, where it divides into the
right and left bronchi (page 268). It is situated partly in the neck, and
partly within the superior mediastinum of the thorax (page 260). The
length of the trachea in the adult is from ten to eleven and a half centi-
metres, or from four to four and a half inches, and its diameter is about
nineteen millimetres, or three-fourths of an inch, from before backward,
and a little more than that from side to side. The dimensions vary with
the age and development of the individual, and in the female the trachea
is smaller than in the male. In a general way the calibre may be said to
correspond to the size of the patient’s forefinger. It is a cylindrical tube
flattened behind, so that upon section it appears shaped like the letter D
(Plate 26, Fig. 2, No. 7). It is composed of a series of incomplete carti-
laginous rings, from sixteen to twenty in number, which extend round the
anterior two-thirds of its circumference. At the posterior deficiency in the
rings, where the trachea is in relation to the cesophagus, the tube is com-
pleted by a fibro-muscular membrane, in consequence of which its calibre
can be increased or enlarged. The muscular tissue consists of layers of
longitudinal and transverse fibres. The spaces between the rings are filled
THE REGION OF THE NECK. 237

up with the fibrous membrane, in which there is an additional development
of elastic tissue. The hoops of the rings are generally parallel with one
another across the front of the tube, but their extremities offer great diver-
sity in conformation. Sometimes they fork, alternating upon the two
sides, and sometimes the ends of the adjacent rings are united. The last
ring is peculiar, and usually is modified by being prolonged in front in a
V-shaped piece so as to conform with the first rings of the two bronchi.
The top ring is always broader than the rest, and is strongly connected by
fibrous tissue with the lower border of the cricoid cartilage, with which it is
sometimes blended. The tracheal cartilages rarely ossify, as they are non-
vascular. They are invested with a dense perichondrium which closely
adheres to the entire tube. The mucous lining of this portion of the air-
passage is smooth and of pinkish color, although it is but slightly vascular.
Within the sub-mucous layer are the blood-vessels, lymphatics, and nerves,
together with a number of small racemose mucous glands, the tracheal
glands. These are situated mostly in the posterior membranous wall and
along the borders of the rings, and their ducts convey their secretion to
the inner lining. In bronchitis they are the sources of the abundant
secretion. The tracheal arteries are supplied by the inferior thyroid
arteries (page 233) and run longitudinally downward to terminate in
capillary plexuses. The nerves are derived from the pneumogastrics and
their recurrent branches. The trachea is surrounded by a quantity of
loose connective tissue, especially in children, which allows of its free
mobility. This mobility of the trachea is one of the greatest obstacles to
the satisfactory performance of tracheotomy, as it is essential to fix the
trachea in the middle line, which here, as elsewhere in the body, is
regarded surgically as the line of safety, owing to the feeble anastomosis
of the vessels from side to side.

In the performance of the operation of tracheotomy, the patient’s
head should be extended straight backward, with the shoulders elevated
over a firm pillow, so as to bring the trachea into relief and to steady it
as much as possible. The landmarks, consisting of the thyroid notch,
the hoop of the cricoid cartilage, and the top of the sternum, are clearly
noticeable. The upper rings of the trachea cannot be detected through the
PSU 92 pore

=

o

10.

12.
18.
14.
15.

16.
17,
18.
19.
20.
21.
22,

23,

PLATE 34.

Preparation to show the relations of the heart, within the pericardium.

The thyro-hyoid membrane.

The thyroid notch.

The right thyro-hyoid muscle.

The right superior thyroid artery.

The right superior laryngeal nerve.

The right crico-thyroid muscle, and crico-thyroid ar-
tery.

The right pneumogastric nerve.

The right common carotid artery.

. The right supra-scapular artery.

The right scalenus anticus muscle.

. The right phrenic nerve.

The right brachial plexus of nerves.

The right subclavian artery.

The right first rib.

The right pneumogastric nerve, passing behind the
right innominate vein.

The innominate artery.

The right innominate vein.

The upper lobe of the right lung, drawn aside.

The superior vena cava.

The right phrenic nerve.

The middle lobe of the right lung, drawn aside.

The position of the right auricle, covered with the
pericardium.

The lower lobe of the right lung.

 

24.
25.
26.
27.
28,
29.
30.
31.
32,
. The left recurrent laryngeal nerve.

42,
43,
44.
45.

46.

The right ventricle of the heart within the pericardium.
The left superior thyroid artery.

The left thyro-hyoid muscle.

The crico-thyroid membrane.

The cricoid cartilage.

The left internal jugular vein.

The left common carotid artery.

The left pneumogastric nerve.

The left brachial plexus of nerves.

The left scalenus anticus muscle.

. The trachea.

. The left subclavian artery.

. The left subclavian vein.

. The left phrenic nerve.

. The left innominate vein.

. The upper lobe of the left lung, drawn aside.

. The position of the pulmonary artery within the peri-

cardium.

The left lung, drawn aside.

The left phrenic nerve.

The apex of the heart within the pericardium.

The lower portion of the lower lobe of the left lung,
drawn aside.

The position where the pericardium blends with the
central tendon of the diaphragm,

N, B.—The ribs are cut away so as to give an unrestricted view.
 

 

IREEMC CLELLAN

pyright/890,by Gc

 
THE REGION OF THE NECK. 239

integument, except in very thin subjects. The isthmus of the thyroid
body crosses over the second and third tracheal rings, and is usually very
closely bound down to them. It should be remembered that the crico-
thyroid artery passes over the top of the crico-thyroid membrane (page
184), that occasionally the anterior jugular vein occupies the middle line
(page 192), and that the inferior thyroid veins always intercommunicate
over the trachea at the root of the neck (page 235). These anatomical
facts indicate the isthmus of the thyroid body as the point above which
or below which the operation offers special features of interest. In all cases
it is well to make the incision through the superficial tissues free; and it
should be kept absolutely in the middle line. It should divide the skin
over the position of the isthmus of the thyroid body, when the anterior
jugular vein, if present, will be recognized, and the white aponeurotic line
between the sterno-hyoid and sterno-thyroid muscles will be exposed. The
surface of the crico-thyroid membrane should be carefully examined for the
presence of any transverse vessel,—the crico-thyroid or superior thyroid,—
and traction should be made upon the isthmus to see whether it can be
drawn upward or downward. If it cannot be displaced it may be cut
through upon a director, and, if necessary, between a double ligature.
When the trachea is sufficiently exposed, a tenaculum should be inserted
to steady it, and the upper rings cut by plunging into them the point of
the knife to the extent of half an inch, so as fully to open the mucous
lining. This precaution is necessary when there is a false membrane, so
that the canulated metal tube when inserted may not pass between it and
the tracheal wall. It is not safe to make the plunge with the knife deeper
than half an inch, on account of the danger of wounding the cesophagus.
It is noticeable that when air enters the lungs through the tracheal wound
the engorgement of the tributary veins subsides in consequence of the
relief afforded to the heart, which is thus enabled to pump out the venous
blood from its right side. Below the isthmus of the thyroid body the
trachea becomes deeper as it descends behind the sternum (page 190),
which adds greatly to the difficulty of opening it in this situation. In
little children the neck is usually very fat, and at the root of the neck,
besides the intricate inferior thyroid veins, the /eft innominate vein, and
240 THE REGION OF THE THORAX.

even the innominate artery, may be drawn upward above the margin of
the manubrium sterni, in consequence of the comparatively greater laxity
of the connective tissue. The upper portion of the thymus gland is also
often in the way. In the adult, however, unless there is an unusual origin
for the innominate artery, it can hardly be made to mount so high as the
supra-sternal notch by stretching the neck, as already stated (page 222).
In operating below the isthmus the inferior thyroid veins should never be
forgotten, and the knife should be introduced with the back toward the
sternum, to avoid the thymus gland and other structures in that situation.

THE REGION OF THE THORAX.

The landmarks of this region are so obscured by the superficial and
external structures that they are not easily recognized without particular
knowledge of the. component parts in their several localities. They are
of the greatest importance, on account of their medical application in the
physical examination of the chest as relates to diagnosis by auscultation
or percussion in affections of the thoracic organs. Attention will therefore
be first drawn to the general construction of the thorax, and then to its
principal features in detail, before considering its topographical relations.

The skeleton of the thorax (Plate 28) is composed of the dorsal
vertebra, the ribs and costal cartilages, and the sternum, so arranged as to
form a conical, movable framework, which gives attachment to the muscles
of respiration, and affords protection to the heart and the lungs. The
method of the articulation of the ribs with the dorsal vertebre behind,
and with the sternum through their cartilages in front, is one of the most:
ingenious pieces of mechanism in nature, which not only permits the
unceasing momentary alterations in capacity of the thoracic cavity during
respiration, but also fulfils the function of support and protection.

The ribs are twelve pairs of flattened, bony hoops, which are attached
to the spinal column between the neck and the loins, and so arranged that
they project anteriorly and describe a series of arches which increase in
length to the seventh and in obliquity to the ninth from above downward.
The obliquity of the ribs is so great that the sternal end of any rib is on
THE REGION OF THE THORAX. 241

a level with the vertebral end considerably below it in numerical order.
Thus, the first rib in front corresponds to the fourth rib behind, the fifth
to the ninth, the seventh to the eleventh. The seven upper ribs- have
separate cartilaginous prolongations which connect them with the sternum,
and are distinguished as érue or sternal ribs, whereas the lower five are
called false or asternal ribs, because they are not joined directly with the
sternum. Of the latter, the eighth, ninth, and tenth ribs have cartilagi-
nous prolongations which unite and turn upward to join the cartilage of
the seventh rib so that they are brought indirectly in connection with the
sternum. The eleventh and twelfth ribs are without cartilages and termi-
nate in free ends in the muscular walls of the abdomen, and hence are
called floating ribs. Very rarely the eighth rib presents the anomaly of
having an independent cartilaginous prolongation to the sternum (Plate
29), and therefore would then come within the classification of a true rib.
Each rib is peculiarly modified in conformation to its position in the series,
and from the first to the last they are so remarkably adapted that the
slight rotation which can take place only at their vertebral articulations
occasions not only a slight elevation of their sternal ends, but an eversion
of their lateral surfaces, so that by their united action the thoracic cavity
is enlarged in every direction. The vertebral extremities or heads of the
intermediate ribs, which closely resemble one another in all respects, are
covered with articular cartilage, which in all but the first and last three
is divided by a slight transverse ridge into two facets for articulation with
the bodies of two contiguous vertebra. The lower facet is the larger,
and is received upon the vertebral body which corresponds numerically
with the rib.

The costo-vertebral joints are each provided with a capsular ligament,
including two synovial membranes separated by a fibro-cartilaginous inter-
articular ligament, which extends from the intervertebral disk to the
transverse ridge between the facets on the head of the rib. These joints
are reinforced anteriorly by fibres which radiate from the anterior border of
the head of each rib to the side of the body of the vertebra above, to the
front of the intervertebral disk, and to the front of the body of the vertebra

below, forming the stellate hgament. The narrowed portion beyond the
31
242 THE REGION OF THE THORAX.

head of each rib is called the neck. This is smooth in front, but roughened
behind for the attachment of the posterior accessory ligament, consisting
mostly of transverse fibres which connect it with the front of the transverse
process of the corresponding vertebra. The neck is generally two and a
half centimetres, or about an inch, in length, and ends in a roughened
process called the tuberosity, which presents on its inner surface a smooth
oval facet for articulation with the end of the transverse process of the
vertebra. This is also provided with a delicate capsular ligament and
encloses a synovial membrane.

The fibres which connect the necks and tubercles to the transverse
processes are called, from their relative positions, anterior, middle, and pos-
terior costo-transverse ligaments. The anterior consists of a broad band of
fibres extending between the upper border of each rib to the lower border of
the transverse process above. It is in relation in front with the intercostal
vessels and nerves. The middle consists of short fibres which pass from the
back part of the neck of each rib to the anterior surface of the adjacent
transverse process. The posterior consists of a short, strong band which
passes obliquely from the top of the transverse process to the neck of the rib
just back of the tubercle. Between the last two ribs and the transverse
processes of the corresponding vertebre the middle and posterior costo-
transverse ligaments are very loose and allow considerable freedom of
motion to these ribs. It should be noted in this connection that, the trans-
verse processes of the dorsal vertebrae become more oblique from above
downward, and consequently the obliquity of the neck of each rib increases.
Beyond the tuberosity each rib is prolonged forward as a narrow, flattened,
bony hoop, constituting the body or shaft. The inner surface is concave
and smooth, and the outer surface is rough. The upper border is rounded
and thick, and gives attachment to the internal intercostal muscles. The
lower border is grooved for the accommodation of the intercostal vessels and
nerve, and presents a sharp external edge for the attachment of the external
intercostal muscle. The body of each rib from the second to the tenth at a
short distance from its neck suddenly bends forward and changes the direc-
tion of its curve. At this point of divergence there is upon the external
surface an oblique ridge called the angle, which upon each successive rib
THE REGION OF THE THORAX. 243

downward is situated farther outward, and corresponds to the insertion
of the slips of the sacro-lumbalis muscle. Furthermore, as each rib
approaches its sternal end there is a tendency for the body to twist in its
axis, so that the posterior surface behind the angle is inclined downward
and inward, while toward the middle of the body the bone is inclined
downward and outward. This gives the spiral shape which can best be
appreciated when an isolated specimen is placed upon a flat surface, it
being then found that both ends cannot be kept down at the same time.
In consequence of the obliquity and curvature of the ribs, a pistol-ball
upon striking one of them may be deflected in its course, and if it has
entered in front may be found in the muscles of the back, or if it has
entered from behind may pass out near the sternum. The sternal portions
of the ribs are broader, thicker, and more porous than elsewhere, and have
cupped depressions in their ends to receive the costal cartilages.

The ribs which have noteworthy individual peculiarities are the two
upper and three lower ribs upon each side. The first rib is broad, nearly
flat, and very curved, but without any twist in its axis. It has a small
rounded head, which has only one articular facet for articulation with the
body of the first dorsal vertebra. The neck is long and slender and
ends in a decided tuberosity. In very pronounced specimens the upper
surface presents two shallow oblique impressions in front of the middle
of the body, which are separated by a slight ridge. The posterior impres-
sion is for the subclavian artery, the anterior part of the ridge for
the attachment of the scalenus anticus muscle (page 220), and the anterior
impression for the subclavian vein. Between the tuberosity and the
impression for the subclavian artery there is a rough surface for the
scalenus medius muscle. The second rib is not so broad as the first,
and conforms more to the succeeding ribs below, but it is without any
twist and is also flatter. The head is provided with two facets for
articulation with the bodies of the first and second dorsal vertebree.
About the middle of the body there is a roughness for the attach-
ment of the scalenus posticus and serratus magnus muscles. On both
the first and the second rib the angle is very slightly developed. The
tenth rib is long and curved, and has only a single facet on its head.
e

Om Oo bo

PLATE 835.

Preparation to show the relations of the heart and the great vessels at the root of the neck. The pericardium is
opened and held aside.

. The thyroid notch.

. The right common carotid artery.

. The right superior laryngeal nerve.

. The right superior thyroid artery.

. The crico-thyroid membrane, with the crico-thyroid

artery.

. The cricoid cartilage.

The right supra-scapular artery.

. The right scalenus anticus muscle.

. The right subclavian artery.

. The right brachial plexus of nerves.
. The right first rib.

. The right pneumogastric nerve.

. The innominate artery.

. The right recurrent laryngeal nerve.
. The right innominate vein.

. The right phrenic nerve.

. The transverse arch of the aorta.

. The superior vena cava.

The upper lobe of the right lung, drawn outward.

. The pericardium drawn outward to expose the root of

the heart.

. The right auricle of the heart.

. The middle lobe of the right lung.

. The right coronary artery of the heart.

. The pericardium opened and resting upon the dia-

phragm.

 

25.
26,

27,

28.
29

30.

31,
382.
33.
34.
35.
36.
37.
38.
39.
40.

41.
42,

43,
44,
45.
46.
47.

The lower lobe of the right lung.

. The left thyro-hyoid muscle.
. The left superior thyroid artery.

The left superior laryngeal nerve.

. The left internal jugular vein.
. The left common carotid artery.

The left scalenus anticus muscle.

The left brachial plexus of nerves.

The left pneumogastric nerve.

The left subclavian artery.

The left subclavian vein.

The left recurrent laryngeal nerve.

The left innominate vein.

The upper lobe of the left lung, drawn aside.

The descending portion of the arch of the aorta.

The ascending portion of the aorta.

The pulmonary artery.

The upper portion of the pericardium, drawn aside to
show the root of the heart.

The left coronary artery of the heart.

The lower lobe of the left lung, drawn aside.

The right ventricle of the heart.

The apex of the heart.

The lower portion of the pericardium, drawn aside to
show the apex of the heart.
 

 

Copyright /690,by GeorceMc Crean, M.D
THE REGION OF THE THORAX. 245

The eleventh and twelfth ribs are less well developed in every respect
than the others, and have each a single facet on the head, but are with-
out neck or tubercle and terminate in sharp-pointed extremities. The
difference between them is that the eleventh has a slight angle and
groove on its under border, while the twelfth has neither. Occasion-
ally there is found a rudimental thirteenth rib on one or both sides
in either the cervical or the lumbar region. The sixth, seventh, and
eighth ribs are those most frequently fractured, on account of their being
usually more exposed than the others.

The cartilaginous prolongations of the ribs, or costal cartilages, which
bring them in connection with the sternum, resemble in shape the sternal
ends of the bony ribs, into which they are fitted without articulation, being
merely adjusted and enveloped in a thick perichondrium. In length
they increase downward to the seventh, and thence gradually decrease.
The first costal cartilage corresponds in breadth to its proper rib, and,
like the second, third, and fourth costal cartilages, which are narrower, is
continued to the sternum in the line of its rib. The cartilages of the
lower true ribs, also narrow, converge upward to be joined to the sternum ;
the seventh is the largest, and receives the cartilage of the eighth rib at
its under surface, as the eighth does that of the ninth and the ninth
that of the tenth. The cartilages of the floating ribs are merely tips to
the bones. The union of the several cartilages with the sternum offers all
the characteristics of a joint, with special differences in some instances.

The first chondro-sternal joint is a synchondrosis, the cartilage being
continued into a depression on the outer angle of the top of the manubrium
sterni, which admits of very little motion. This cartilage is often partially
or completely ossified at middle life. The second chondro-sternal joint
occurs at the junction of the manubrium with the gladiolus of the sternum,
and consequently there are double articular surfaces, with an interarticular
fibro-cartilage and a synovial membrane. This joint is of topographical
value, as it can be located through the superficial structures by its
relation to the constant ridge between the manubrium and gladiolus sterni
(Plate 28). The succeeding costal cartilages are joined to the margins of
the sternum in a manner very closely resembling the attachment of the
246 THE REGION OF THE THORAX.

head of the first rib to the body of its vertebra. The seventh chondro-
sternal jowmt often resembles the first, and has slight motion. Each of
these joints is provided with a capsule from the adjoining periosteum,
which is strengthened by the anterior chondro-sternal ligament, composed
of fibres radiating from the ends of the costal cartilages on the front
of the sternum, where they interlace with one another above and below
and from the opposite side and with the tendinous attachments of the
pectoral muscles. The posterior chondro-sternal ligament is the corre-
sponding fibrous interlacement on the endothoracic surface of the articu-
lations. The cartilages of the eighth, ninth, and tenth ribs are connected
to one another and to the cartilage of the seventh rib by the interchondral
ligaments. The costal cartilages are very elastic in youth, those of the
lower ribs particularly so. In certain diseased conditions these cartilages
become ossified and are liable to fracture.

The sternum, or breast bone, consists in the adult of three light, flat,
spongy bones which are supported by the costal cartilages in the front
of the chest, and taken together form a narrow, long, bony mass shaped
somewhat like an old Roman sword. The upper portion resembles the
handle, and is called the manubrium (or presternum), the central blade-like
portion is the gladiolus (or mesosternum), and the lower pointed process
(usually cartilaginous) is the ensiform process (or metasternum), which,
because of its variability of form and frequently forked termination, is
also known as the xiphoid appendix. The manubrium is the broadest and
thickest part, and presents on each lateral border three articular surfaces,
the upper of which is the largest, for the articulation with the clavicle
(page 324), the middle just below it for the cartilage of the first rib, and
the lower half facet for the upper border of the cartilage of the second
rib. The upper border of the manubrium is on a level with the lower
border of the second dorsal vertebra, is smooth, and is noticeable through
the skin between the two sterno-clavicular joints as a marked depression,
called the supra-sternal notch.

The gladiolus is ordinarily broadest between the articulations of the
cartilages of the fifth ribs. Upon the lateral borders are the articular
notches for the rib cartilages, and running across the bone between them
THE REGION OF THE THORAX. 247

from side to side are imperfectly-marked ridges, indicating the original
segmentation in its formation. The ensiform cartilage is irregular, notched
or bifid, and is, often bent forward or to one side owing to some habitual
occupation during life, as the pressure exerted by a cobbler’s last. There
is a chondro-xiphoid ligament which extends from the cartilage of the
eighth rib on each side to this process.

The chief difference in the length of the sternum in the female (seven-
teen and a half centimetres, or about seven inches) and in the male (twenty
centimetres, or about eight inches) is in the gladiolus, which in the former
(Plate 41, Fig. 1) is shorter and. broader proportionately than in the
latter (Plates 28 and 29). The outer surface of the sternum is slightly
convex, the inner concave. Looked at from the side, the anterior
surfaces of the different portions will be seen to occupy different planes,
so that there is always a slight bend at the junction of the manubrium
and gladiolus. The plane of the manubrium inclines forward, that of the
gladiolus less so, and the ensiform cartilage is usually vertical, although, as
just stated, it is subject to variations. The outer layer of compact tissue
which encases the spongy substance of the sternum affords very slight pro-
tection, but the periosteal covering is very dense, and thicker than usual in
other bones. The joint between the manubrium and gladiolus is rarely
ossified, and there is often a decided yielding or tendency to sinking back-
ward of the top of the gladiolus, which has in some instances been errone-.
ously surmised to be the result of fracture. As stated, the ridge in this
situation is constant, and of the greatest service in counting the ribs, for,
as it corresponds to the attachment of the cartilage of the second rib on
each side (page 245), it is easy to ascertain any other by counting down-
ward. The median line of the sternum is not continuous with the median
line of the abdomen, but inclines rather to the right.

The wntercostal spaces in relation to the sternum are noticeably wider
above and narrower below. The second intercostal space is generally the
widest (Plate 29), but they all vary with the expansion and contraction
of the chest in respiration. They can be increased by bending the body
over to the opposite side.

The skeleton of the thorax, considered as a whole, is somewhat flattened
248 THE REGION OF THE THORAX.

in front and behind, so that its width from side to side exceeds its depth,
which is characteristic of the human thorax as compared with that of
quadrupeds, and makes the supine position naturally an easy one to man.
The anterior surface is slightly convex, corresponding to the direction of
the sternum and the costal cartilages by which it is formed. The lateral
surfaces are convex, and formed by the arching bodies of the ribs and the
intercostal spaces. The posterior surface is also convex from above down-
ward, and is formed by the dorsal vertebrae and the portions of the ribs
posterior to their angles. The thorax increases in dimension from the first
rib to the eighth, where its transverse diameter is greatest. There is much
variability in the form of the thorax at all periods of life, and very com-
monly there is a want of symmetry in the two sides, the circumference of
the right usually being greater than that of the left. In early childhood
the thorax is relatively smaller than in the adult, the ribs are flatter and
less hooped, and up to the end of the third year breathing is more abdom-
mal than thoracic, while after that age, in boys, and in men too, it is
effected by the action of the muscles attached to the lower seven ribs as
well as the diaphragm. In adult females the upper portion of the thorax
is less compressed from before backward, and the upper ribs are naturally
brought more into play, even when not influenced by artificial pressure,
so that in them breathing is thoracic. A horizontal section made through
the middle of the thorax (Plate 41, Fig. 2) presents a cordiform or heart-
shaped outline, owing to the projection of the bodies of the dorsal portion
of the vertebral column into the back of the thoracic cavity. Such a sec-
tion will also show that the ribs are cut obliquely. In the male a section
made on a level with the lower borders of the third ribs anteriorly and
through the body of the eighth dorsal vertebra posteriorly will generally
cut the eighth, seventh, sixth, fifth, and fourth ribs (Plate 41, Fig. 2).
The dorsal vertebre,, or, more properly, thoracic vertebre, are peculiarly
adapted with facets and demi-facets for the articulation of the ribs. The
Jjrst corresponds in general conformation to the vertebra prominens of the
neck, and the ast to the first vertebra of the lumbar region. Their bodies
are thicker behind than in front, as are also the dorsal intervertebral disks,
so that when they are articulated they present a natural curvature with the
THE REGION OF THE THORAX. 249

convexity backward. The dorsal spines are very oblique, and it should be
remembered that their tips do not correspond to the bodies. That of the
first is opposite the disk between the first and second bodies; that of
the second is opposite the body of the third; that of the fourth is on a level
with the disk between the fifth and sixth; those of the fifth, sixth, seventh,
and eighth are opposite the seventh, eighth, ninth, and tenth. That of
the ninth corresponds to the body of the tenth, the tenth to the eleventh,
and the eleventh is opposite the disk between the eleventh and twelfth.
The further description of the dorsal vertebree will be found under the
anatomy of the back, in Vol. II.

The terms superior and inferior apertures of the thorax are misleading,
such openings existing only in the skeleton. The superior, corresponding
to the swmmit of the thorax, gives passage to the structures at the root
of the neck and to the dense fibro-cellular tissue which is prolonged over
them from the deep cervical fascia into the thoracic cavity. The inferior
opening, or Jase, is closed in the recent state by the diaphragm, which
forms a muscular partition between the chest and the abdomen. Although
the diaphragm is arched upward to a considerable extent and its muscular
portions fall and rise continually in unison with the efforts at respiration,
thereby alternately increasing and diminishing the capacity of the thorax,
the actual space occupied by the lungs and heart is very limited compared
to that indicated by the outward appearance of the bony cage. The dia-
phragm (page 320) is on a level with the junction of the fifth costal carti-
lage and rib on the right ride, and of the sixth on the left (Plate 27),
corresponding to the height to which the liver reaches. It is attached in
front to the ensiform cartilage, but it curves downward to become attached
to the last rib on both sides.

The skin over the anterior surface of the thorax is delicate and closely
connected with the superficial fascia. It is tense and very slightly movable
over the sternum, but at the sides, in consequence of the traction exerted
by the underlying muscles, the:pectoralis major and minor and the latissi-
mus dorsi, forming the folds of the axilla, it is freely movable. The skin
over the sternum in dark-hued males is usually the seat of the growth of

curly black hairs associated with large sebaceous glands. The superficial
382
250 THE REGION OF THE THORAX.

fascia is generally loose, and does not contain much fat except in relation to
the mamme, where the fascia subdivides into two layers which surround
these glands and send numerous septa between their various lobes. The
ligamenta suspensoria are fibrous processes which project from the anterior
layer to the skin around the nipples.

The mammary glands in the female (Plate 44, Fig. 1) extend from
the third to the sixth rib on each side between the axille and the sternum.
They vary in size and shape according to their functional development
and the general physical condition of the individual. When fully formed,
with the enveloping skin, fascia, and fat, they appear as globular promi-
nences, the SJreasts, from which protrude conical, brownish-pink-colored
eminences, the nipples, which are surrounded at their bases by a zone of
colored skin, the areola. The nipple is usually situated opposite the fourth
intercostal space, and twelve centimetres, or about four and a half inches,
from the middle line; but its position is variable and cannot be relied upon
as a reference for definite measurement (Plate 27). The skin of the areola
is extremely thin, and is covered with a number of little whitish tubercles
which contain the orifices of sebaceous glands. The skin of the nipple is
provided with sensitive papille, and consists of retiform tissue interspersed
with unstriped muscular fibres. It is highly vascular. The milk-ducts
open upon the summit of the nipple by from fifteen to twenty orifices.
The mammary gland is a racemose glandular structure, consisting of
from fifteen to twenty lobes, which are supported by the septa inflected
from the anterior layer of the fascial investment. The lobes are quite
independent of one another, so that in mammary abscess it is often
necessary to make several openings, and they should be made in a
straight direction radiating from the nipple, in order to avoid as far as
possible injuring the milk-ducts.

The arteries which enter the margins of the gland are small and
numerous, and they do not accompany the ducts. Those for the upper
lobes are derived from the thoracico-acromial artery, those for the outer
lobes from the long thoracic and external mammary arteries, and those for
the inner lobes from the anterior intercostal arteries (Plate 44, Fig. 1).
The deep veins accompany the arteries; the superficial veins form an
THE REGION OF THE THORAX. 251

anastomosing circle around the base of the nipple and end in the supe-
rior thoracic veins.

The lymphatic vessels are numerous, and chiefly converge toward the
axillary glands, following the outer border of the great pectoral muscle
(Plate 44, Fig. 2), while others terminate in the anterior mediastinal
glands in relation to the internal mammary vessels (Plate 41, Fig. 1),
penetrating the thoracic walls through the upper three intercostal spaces.
The distinction between the sub-sternal and axillary glands with reference
to their possible involvement in cancer should be clearly understood. The
former receive the lymphatic vessels from the inner portion of the breast,
so that in cases where they have become implicated they are anatomical
obstacles to the effectual removal of a scirrhous breast, notwithstanding
the most thorough enucleation of the axillary glands with the tumor.
The superficial lymphatics from the vicinity of the nipple pass to a gland
below the outer border of the clavicle.

The nerves are chiefly derived from the anterior and lateral cutaneous
branches of the intercostal nerves. The superficial fascia along the border
of the sternum is pierced by the anterior cutaneous branches of the inter-
costal nerves, which emerge with the anterior intercostal branches of the
internal mammary artery, the second, third, fourth, and fifth being dis-
tributed to the mammary gland. The connections of the intercostal nerves
explain the diffusion of pain complained of in many affections of the
breast. In the female there is always a loose layer of connective tissue
underneath the gland, and often a bursa, which allows it to glide freely over
the pectoral muscle, to which it is in no way attached in the healthy state.
In the male the gland is rudimental, and, as the substratum of connective
tissue is less loose, it follows to a greater extent the movements of the
pectoralis major muscle. Occasionally the male mamme are developed,
and in rare instances have been known to secrete milk; and there are
numerous recorded cases of supernumerary mamme in the female, variously
situated in the back, axilla, groin, and thigh. In the female the various
modifications which the breasts assume after puberty are coincident with
the other phenomena attendant upon pregnancy.

In the operation for removal of the breast the arm of the affected side
SIRO kw

2

10.
la

PLATE 36.

Dissection of the pneumogastric nerve on the left side, and its relations to the phrenic and sympathetic nerves.
(From a female, aged thirty-seven years.) :

. The parotid gland.

. The digastric muscle.

. The styloid process. ;

. The stylo-glossus muscle.

. The lingual (or gustatory) nerve,

The hypoglossal nerve.

. The glosso-pharyngeal nerve.
. The lingual artery.
. The digastric muscle attached to the hyoid bone by the

’

loop of deep fascia.

The great cornu of the hyoid bone.

The attachment of the omo-hyoid muscle to the hyoid
bone.

. Section through the symphysis of the lower jawbone.
. The superior laryngeal nerve.

. The crico-thyroid muscle.

. The superior thyroid artery.

. The top of the thyroid cartilage.

. The descendens hypoglossi nerve.

. The right sterno-thyroid and hyoid muscles.

. The thyroid body.

. The internal jugular vein.

. The pneumogastric nerve.

. The lower cervical ganglion of the sympathetic nerve.
. The common carotid artery.

. The recurrent laryngeal nerve.

. The innominate artery.

. The sternal end of the right clavicle.

. The left innominate vein.

28. The left first rib.

x

. The anterior margin of the right lung.

. The ascending portion of the arch of the aorta.
. The right second rib.

. The right auricle.

. The right third rib.

. The left phrenic nerve.

. The apex of the left ventricle of the heart.

. The branches of the posterior coronary artery.
. The right fifth rib.

. The right sixth rib.

39.
. The diaphragm over the liver.
41.
42,
43.
44,
. The trapezius muscle.
46.
47.

The gastric branches of the left pneumogastric nerve.

The right seventh rib. ‘

The sawn end of the ramus of the lower jawbone.
The occipital artery.

The spinal accessory nerve.

The internal jugular vein.
The second cervical spinal nerve.

 

48,
49.

90.
91,
92.

The third cervical spinal nerve.

The upper—long—cervical ganglion of the sympathetic
nerve.

The external carotid artery.

. The internal carotid artery.

. The descendens hypoglossi nerve.

. The omo-hyoid muscle.

. The scalenus anticus muscle.

. The sympathetic nerve.

. The left phrenic nerve.

. The cords of the brachial plexus of nerves.

. The subclavian artery.

. The subclavian vein.

. The insertion of the scalenus anticus muscle at the inner

border and upper surface (tubercle?) of the first rib.

. The pneumogastric nerve.
. The esophagus (distended).
. The first intercostal artery coming from the subclavian

artery. :

. The internal mammary artery.

. The left innominate vein.

. The second intercostal artery and nerve.

. The origin of the subclavian artery.

. The left third rib.

. The sympathetic nerve.

. The left third intercostal artery and nerve.

. The transverse portion of the arch of the aorta,
. The left fourth rib. |

. The left fourth intercostal artery and nerve.

. The left fifth rib.

. The pulmonary artery.

. The left fifth intercostal artery and nerve.

. The roots of the pulmonary vessels and bronchi.
. The sixth intercostal artery and nerve.

. The esophageal branches of the pneumogastric nerve.
. The great splanchnic nerve.

. The left auricle of the heart.

. The seventh intercostal artery and nerve.

. The lesser splanchnic nerve.

. The azygos minor vein.

5, The pneumogastric nerve.

. The left eighth rib.

. The diaphragm arching over the spleen.

. The phrenic nerve.

. The gastric branches of the pneumogastric nerve pass-

ing through the diaphragm to the stomach.
The terminal branches of the pneumogastric nerve.
The spleen.
The stomach.
ted, Photographed and Colored from Nature by

Georce Mc. Ciectan, M D0.

 

Copyright/890,by GeoreeMc Ce. an,MD.

 

 

 

 
THE REGION OF THE THORAX. 253

should be drawn upward and backward, so as to put the great pectoral
muscle on the stretch, and a bevelled incision should be made, first on one
side and then on the other, around the base of the gland, in a direction
toward the axilla. The entire gland, including the nipple, should always
be extirpated, to avoid as far as possible a recurrence of the morbid state,
and if the axillary glands are involved, as they generally are in cancer,
the incision can be extended so as to expose them. They will be found
surrounding the deep vessels (Plate 45), and often adherent to the axillary
vein and its tributaries, so that their removal is very difficult and hazard-
ous, whereas the excision of the gland alone is comparatively a simple and
easy task. Upon complete removal of the gland, its base will be found to
conform with the slight bulge of the subjacent pectoralis major muscle,
which with its sheath of deep fascia will be seen usually untouched at the
bottom of the wound.

The deep fascia of the anterior surface of the thorax is exposed after
removal of the double layer of the superficial fascia and the contained
mammary gland. It serves as a thin aponeurotic sheath for the great
pectoral muscle, into which it sends prolongations between its component
fasciculi. This fascia is attached to the front of the sternum and to the
clavicle. It is very delicate over the upper part of the pectoralis major ;
but, as it is reflected from the outer border of that muscle across the
axillary space to the latissimus dorsi muscle, it becomes considerably
thicker. It is continued under the latter muscle to the spinous processes
of the dorsal vertebree. Below the deep thoracic fascia is quite strong and
blends with the sheaths of the recti muscles.

The pectoralis major muscle (Plate 16, and Plate 44, Fig. 1) is the large,
triangular, fleshy mass situated at the side of the chest, consisting of two
special portions, the fibres of which converge toward the shoulder. The
clavicular portion arises chiefly by fleshy fibres from the front of the inner
half of the clavicle and the capsule of the sterno-clavicular joint, and
extends obliquely outward, when the arm is at the side of the body, to
the insertion of the deltoid muscle, with which it blends on the surface
of the shaft of the humerus, and also gives off an expansion to the
brachial fascia. In relation to the deltoid muscle above, the clavicular
254 THE REGION OF THE THORAX.

portion is separated only by a furrow which lodges the cephalic vein and
the humero-thoracic artery. When this furrow is marked, the coracoid
process can be felt through it and may be a useful landmark (page
330). The sternal portion is peculiar in the manner both of origin
and insertion of its fibres, which are arranged in two layers which
are often quite distinct from each other, being separated by a cellular
interval. The superficial layer arises by tendinous fibres from the front
of the sternum interlacing with those from the opposite muscle, and
usually by a slip from the sheath of the rectus abdominis muscle. The
deeper layer arises by fleshy fibres from the cartilages of the five or six
upper true ribs, the slip from the first costal cartilage being sometimes
absent. The fibres of these two layers are directed in a radiating manner
toward their insertion, being disposed in such a manner that the fibres of
the deeper layer pass obliquely upward under the fibres of the superficial
layer, so that their relative positions are reversed, the lower becoming the
upper, as they terminate in a flat tendon at the outer margin of the bicipital
groove under the insertion of the clavicular portion. The attachment of
the sternal portion gives off a delicate expansion which covers the bicipital
groove and is connected with the capsular ligament of the shoulder-joint.
The twist in the sternal portion produces the anterior rounded border of
the axilla, and covers the axillary vessels and nerves at the upper part
of that space.

The pectoralis major muscle is remarkable for its tendency to separate
into radial lamelle, commonly offering accessory slips which pass to the
humerus or the brachial fascia. Its function is chiefly to draw the arm
forward and rotate it inward upon the chest. When the arm is raised it
can draw it downward, or, if the fixed point is above, the muscle can assist
in raising the trunk, and also serve as an auxiliary muscle of inspiration.
The arteries to this muscle come from the long and short thoracic branches
of the axillary artery. The nerves are derived from the anterior thoracic
branches of the subjacent brachial plexus. The cleft between the clavic-
ular and sternal portions of the pectoralis major muscle, when the arm is
extended outward, is often clearly indicated by a depression in the skin,
and, as it corresponds to the course of the commencement of the axillary
THE REGION OF THE THORAX. 255

artery, that vessel may be sought for here and a ligature applied with
considerable ease (page 343).

The pectoralis major muscle must be removed in order to expose the
pectoralis minor and subclavius muscles. The former will be found sepa-
rated from the sternal portion of the pectoralis major by a quantity of loose
cellular tissue, and the latter beneath the clavicular portion, enclosed in the
strong costo-coracoid membrane. The pectoralis minor muscle (Plate 44,
Fig. 2) is a triangular fleshy mass composed of fibres which arise by
flattened tendinous slips from the sternal ends of the third, fourth, and
fifth ribs, and from the aponeurotic expansion over the subjacent inter-
costal muscles. Besides these there are often accessory slips of origin, either
above or below. It ascends to be inserted by a narrow, flat tendon into the
upper and inner edge of the coracoid process of the scapula, and gives a
fibrous extension to the coracoid attachments of the coraco-brachialis and
biceps muscles. The insertion of the pectoralis minor passes across the
middle of the axillary vessels and nerves (page 339). Between the pecto-
ralis minor and major muscles there are branches of the thoracico-acromial
artery and the anterior internal thoracic nerve. The long thoracic artery
runs along the axillary border of the pectoralis minor. The function of
this muscle is to depress the shoulder, by drawing the scapula forward and
downward.

The costo-coracoid membrane consists of several leaflets of fascia of
varying density, extending from the cartilage of the first rib to the coracoid
process. Above it is attached to the outer and inner edges of the sub-
clavian impression on the under surface of the clavicle, and thus com-
pletely encloses the subclavius muscle. The outward and more superficial
expansion is thin, and splits so as to pass over and under the coracoid
attachment of the pectoralis minor muscle, to be continued with the axil-
lary fascia, forming the anterior part of the sheath of the axillary vessels.
This leaflet is pierced by the cephalic vein, the thoracico-acromial artery
and vein, the anterior thoracic nerves, and the superior thoracic artery.
The deeper portion of this membrane is called the costo-coracoid ligament,
because of its strong fibrous character. It arches over the axillary vessels
and nerves as they pass over the first rib.
256 THE REGION OF THE THORAY.

The subclavius muscle is a round mass of fibres which arises by a strong
tendon from the junction of the first rib and its cartilage, and is inserted
into the subclavian impression of the clavicle as far as the coraco-clavicular,
ligament. It receives filaments from the lower cervical nerves, and its
function is to fix and depress the clavicle.

When the above muscles are completely removed from the anterior
surface of the thorax there is a strong glistening aponeurotic layer of
fascia spread over the intercostal spaces, which serves to bind down the
fibres of the intercostal muscles and to afford additional protection to the
spaces. The intercostal muscles consist of two separate layers, external
and internal, the short fleshy fibres of which cross one another. There
are eleven pairs of each set of intercostal muscles, and they are arranged
peculiarly as they approach the vertebral and sternal ends of the ribs.

The eaternal intercostal muscles commence at the tubercles of the ribs,
pass obliquely from the outer border of the rib above to the top of the
rib below, throughout the series, and extend as far forward as the costal
cartilages, where the muscular fibres disappear and are replaced by strong,
oblique, tendinous fibres, which constitute a membranous expansion, to
the border of the sternum. The mternal intercostal muscles commence
at the sternum and pass obliquely in the opposite direction to the external
muscles from the inner edge of the groove above and from the costal car-
‘tilage to the upper border of the rib below, as far backward as the angles
of the ribs, where they are reinforced by additional fibres, the subcostal
muscles, which extend upward and downward, passing over one or two
ribs between their attachments. The direction of the fibres of the external
intercostals corresponds to the external oblique muscle of the abdomen, and
that of the internal intercostals is similar to the internal oblique. The in-
ternal intercostals are thicker and their muscular fibres more pronounced
anteriorly (Plate 40) than they are posteriorly. The intercostal muscles
are exercised chiefly in the movements of the ribs in ordinary breathing.
When the first and second ribs are fixed by the scalene muscles the action
of the external intercostals raises the anterior part of the ribs and everts
their lower borders, thus enlarging the thoracic cavity, as in inspira-
tion. The special action of the internal intercostals is not definitely
THE REGION OF THE THORAX. 257

understood, but they probably depress the ribs, as in expiration. In the
spaces between the costal cartilages the two sets of fibres, it is supposed,
assist each other in inspiration. The internal surface of the intercostal
spaces is covered with a thin adherent fascial’ expansion similar to that
upon the outer side of the chest wall. It is closely connected with the
outer layer of the pleura.

Within the thorax, on the under surface of the sternum and cartilages
of the lower true ribs, there is a thin, flat muscle, of variable development,
called the triangularis sternt. It arises from the ensiform cartilage and
the sides of the lower part of the gladiolus and the adjacent cartilages,
and ascends obliquely outward, to be inserted, by fleshy slips, into the carti-
lages of the lower true ribs, generally from the sixth to the third. The
fibres of the lowest slip pass transversely outward, and are in reality con-
tinuous with the anterior portion of the transversalis abdominis muscle.
The action of the triangularis sterni muscle is to depress the costal carti-
lages in expiration. Its nerves are derived from the intercostal nerves, and
its arteries are branches of the internal mammary on both sides, which are
situated between it and the costal cartilages.

The internal mammary artery on either side is given off from the
first portion of the subclavian artery, opposite the origin of the thyroid axis
at the inner border of the scalenus anticus muscle, and descends into
the thorax behind the clavicle and the first rib, in close relation to the
phrenic nerve, which passes over it from without inward to descend behind
the artery (Plates 39 and 40) between the pleura and the pericardium.
The internal mammary artery with a vein on each side of it runs parallel
with the border of the sternum, and twelve millimetres, or about half an
inch, from it (Plate 41, Figs. 1 and 2), on the surface of the pleura, until it
reaches the fifth or sixth intercartilaginous space, where it passes between
the cartilages and the triangularis sterni muscle. This artery can be
easily ligated within the second intercostal space through an incision
directly over its course. In relation to the seventh costal cartilage it
divides into its terminal branches, the musculo-phrenic, which supplies
twigs to the diaphragm and the lower intercostal muscies, and the superior

epigastric, which enters the abdominal wall between the sheath of the rectus
83
Or A Rw

PLATE 37.

The posterior mediastinum, exposed on the right side by removing the ribs near their angles and drawing forward
the heart and lungs, to demonstrate the entrance of the vena azygos major into the superior vena cava, and the distribu-
tion of the right pneumogastric and phrenic nerves.

. The right occipital artery.
. Section of the sterno-mastoid muscle.

The cut brachial plexus of nerves.

. Section of the first rib.
. Section of the second rib.
. Section of the third rib.

The chain of ganglia of the sympathetic nerve.
The thoracic duct, crossing behind the cesophagus and
aorta to the left side.

. The intercostal vessels and nerve in relation to the

seventh rib.

. The seventh rib.
. The thoracic duct.
. The vertebral column, covered with the thoracic fas-

cia.

. The greater splanchnic nerve.

. The descending thoracic aorta,

. The lesser splanchnic nerve.

. Section of the eleventh rib.

. The hepatic arch of the diaphragm.

. The lingual artery,

. The descending thyroid artery, and superior laryngeal

nerve.

 

20.
-21,
22,
23.
24,
25.
26.
27.
28.
29,
30.

31.
32.

33.
34.
35,
36,

37.

The notch in the thyroid cartilage.

The common carotid artery.

The thyroid axis.

The cricoid cartilage.

The right subclavian artery.

The first intercostal artery.

The trachea.

The cesophagus.

The innominate artery.

The right phrenic nerve.

The vena azygos major vein, entering into the superior
vena cava.

The heart, within the pericardium, drawn forward.

The csophageal plexus of nerves, from the pneumo-
gastric nerve.

The right auricle of the heart, within the pericardium.

The right lung, drawn outward.

The inferior vena cava, emptying into the = auricle
of the heart. .
The thoracic duct, coming through the santle opening

in the diaphragm.
The branches of the right phrenic nerve on the dia-
phragm.
late 37

>

 

 

CLELLAWN, MO.

G

Me

tu
i
5
uy
SS

 

trom WN

27e0

oston.

Armstrong £ Co Lith Bc
THE REGION OF THE THORAX. 259

abdominis muscle and the extra-peritoneal fascia and anastomoses with
the deep epigastric. In its course it distributes a branch which accom-
panies the phrenic nerve, the arteria comes nervi phrenici, branches to the
structures within the anterior mediastinum, branches which pass to the
five or six upper intercostal spaces and inosculate with the aortic inter-
costal arteries, and perforating arteries which pass through the intercostal
spaces and supply the pectoralis major muscle, the mammary gland (page
250), and the skin over the chest. At the first rib there is a lateral infra-
costal branch from the internal mammary, which in intra-thoracic growths
sometimes becomes greatly enlarged. The two internal mammary veins are
usually of unequal size, and are provided with a number of valves. Behind
the first intercostal muscle the veins unite and empty on the left side into
the innominate vein, and on the right, generally, into the superior vena
cava. In close proximity to the internal mammary vessels there are from
six to eight lymphatic glands, which receive the lymphatic vessels from the
upper part of the rectus abdominis muscle, the diaphragm, the intercostal
spaces, and the inner portion of the mammary gland (page 251). They
empty into the right lymphatic duct and left thoracic duct respectively.

If the sternum and costal cartilages are carefully removed, the anterior
wall of the thorax will be opened so as to display the prolongation of the
deep cervical fascia downward and the anterior surfaces of the right and
left pleural sacs. In the middle line there is a tubular expansion of fascia
extending between the pleure all the way from the neck to the ensiform
cartilage of the sternum, and on each side the fascia becomes thickened
and is attached to the pericardium, forming the sterno-pericardial ligaments.
The sub-sternal tubular sheath can generally be demonstrated by inflation
with a blow-pipe, and may allow pus to travel from the root of the neck and
point below the ensiform cartilage in the upper part of the abdominal wall.
Upon slitting up this layer of fascia the subdivision of the interpleural
space, called the anterior mediastinum, is exposed (Plate 26, Fig. 1). This
is a shallow space included between the anterior portions of the pleure,
the pericardium, and the sub-sternal fascia just described, especially that
portion of it which corresponds to the gladiolus. Its direction is usually not
vertical, as it inclines to the left side because of the position of the heart,
260 THE REGION OF THE THORAX.

over the root of which, opposite the origin of the great vessels, it is also
narrowest, owing to the approximation of the pleure. As the left pleura
recedes from the middle line, this space is wider below than it is above.
Within the anterior mediastinum there are the sub-sternal lymphatic
glands, embedded in a variable amount of fatty tissue, and on the left
side the internal mammary vessels for a part of their course (Plate 41).
The space does not properly enclose the attachments of the triangularis
sterni, sterno-hyoid, and sterno-thyroid muscles, as they are covered by
reflections of the endothoracic fascia continuous with the deep cervical
fascia. The so-called superior mediastinum is that portion of the inter-
pleural space which extends from the manubrium in front to the upper
dorsal vertebree behind and above the pericardium. It contains, besides
the great vessels and contiguous portions of the trachea and cesophagus,
the thymus gland in the infant or its remains in the adult. It is not
truly separated from the anterior mediastinum except when the expan-
sion of the lungs in full inspiration brings their pleural envelopes into
contact.

The thymus gland is a soft, grayish-red-colored, lobulated body, of
variable size and shape, situated behind the manubrium sterni and over-
lapping the great vessels of the heart covered with the pericardium (Plate
26, Fig. 3, No. 6). At birth it is five centimetres, or about two inches, in
length, wider below than above, and it continues to grow until the end of
the second year, often ascending into the root of the neck, and sometimes
reaching the lower border of the thyroid body. From the second year to
the sixth it does not undergo much change, but after the latter age it
gradually atrophies, and at puberty there is very little trace of its original
glandular structure left, a fatty mass taking its place and rarely projecting
above the sternum. It bears much resemblance to the racemose glands, but
its function is unknown. It seems to be the great functional lymphatic
gland of early life, each lobe consisting of lobules composed of clusters
of lymph-follicles surrounded with vascular connective tissue and numerous
lymph-cells. The branches from the internal mammary arteries furnish
it with most of its blood.

The pleurz (Plate 26, Fig. 1, Nos. 6 and 16) are the serous mem-
THE REGION OF THE THORAX. 261

branes surrounding the lungs, and are so arranged as to form two distinct
completely closed sacs, each having a parietal layer, or pleura costahs,
which is in contact with the thoracic wall, and a visceral layer, or pleura
pulmonis, which is reflected over the contained lung. The enclosed space
between the two layers of each pleura is called the cavity of the pleura, the
surfaces of which are smooth and moist, but it is not ordinarily of appre-
ciable dimensions. It is now regarded as a large lymph-space, like that
of the peritoneum, and communicates by stomata with the surrounding sub-
pleural lymphatic vessels. During life, when healthy, the two layers glide
freely upon each other, and thereby facilitate the movements of the lungs.
The costal pleura is the thickest, and is connected especially to the inner
surfaces of the ribs by a well-marked connective tissue, which allows of its
being easily detached. The pulmonary pleura is very delicate and trans-
parent, and is also attached to the lung tissue by elastic connective tissue,
which serves as a nidus for a plexus of capillaries from the bronchial
arteries, and a plexus of lymphatic vessels which communicate with the
lymph-spaces in the areolar tissue of the lobules of the lung. Inflamma-
tion of the pleura may produce a thickening and roughening of its lateral
surfaces, so that in the expansion of the lung a friction sound is produced.
This is peculiarly modified if the inflammation results in a distention of the
pleural sac by serum (hydrothorax), or by pus (empyema), or by air (pneu-
mothorax). When the cavity of the pleura requires tapping (paracentesis
thoracis) to evacuate it of an accumulation of fluid, the sixth or seventh
intercostal space, midway between the sternum and the spine, is generally
selected, and the trocar should always be introduced at the middle of the
space, during inspiration, to avoid the intercostal vessels and nerves. On
the right side the fifth intercostal space should be selected, in order to
avoid the diaphragm (Plate 27). The right and left pleural cavities are
distinct, and their respective membranes are reflected posteriorly from the
roots of each lung, in connection with a fold of the prevertebral fascia, to
the diaphragm below, having a free curved edge between the diaphragm
and the lung. This is called the ligamentum pulmonale. As the apices of
the lungs extend upward into the root of the neck behind the attachments
of the scalene antici muscles on the first ribs, their pleure naturally are
262 THE REGION OF THE THORAX.

similarly expanded. On the right side the pleura usually reaches a little
higher than on the left. In this position it bears an important relation
to the subclavian artery in its first portion. At the root of the neck the
endothoracic fascia is expanded somewhat in the shape of a dome, to
which the deep cervical fascia is usually attached. -Sometimes there is a
prolongation of this fascia, which brings the dome into relation with the
transverse process of the seventh or sixth cervical vertebra, and a few
muscular fibres have been found in it, probably segmented from the sca-
lenus posticus muscle. The parietal layer of the pleura over the apex of
each lung is intimately connected with this dome-like expansion of the
fascia. The presence of this ewtra-pleural fascia at the root of the neck,
with its possible modifications consequent upon any inflammatory infiltra-
tion, is worthy of the consideration of the physician, who may be confused
by the adventitious sounds produced by it upon auscultation, in the same
manner as the surgeon finds it often difficult to distinguish between true
and false crepitus in injuries about the joints. The extent and limitation
of the reflections of the pleuree upon the inner wall of the thorax are
very difficult to understand without actual demonstration. Below they
practically follow the attachments of the diaphragm, which, except about
its margin and at its central tendon, is covered by the pleure. In front
the right pleura holds a position more nearly the middle line, being oppo-
site the junction of the seventh rib and its cartilage, while the left is placed
at a variable distance away from it and a little lower, in consequence of the
interposition of the heart. Posteriorly both pleure descend as far as the
head of the last rib, and laterally the right pleura is in relation to the
lower border of the nenth rib, and the left pleura to the lower border of
the ¢enth rib. In consequence of this disposition of the pleuree over the
diaphragm it often happens that a pistol-ball which has penetrated the
thoracic wall will roll down over the diaphragm to the lowest part of
the back of the pleural cavity.

The pulmonary layers of the pleura upon each side are not coex-
tensive with the costal layers, except during forced inspiration. Therefore
there are portions of the folds of the pleuree where their surfaces ordi-
narily are in contact. These are called the pleural sinuses, and they
THE REGION OF THE THORAX. 263

are found along the costal origins of the diaphragm, between the peri-
cardium and the sternum, and between the pericardium and the dia-
phragm (Plate 26, Fig. 1, No. 8). Upon the anterior margins of the
last two sinuses there are folds which blend with the tissue of the peri-
cardium, and through which the phrenic nerves on their way to the
diaphragm can be seen in front of the roots of the lungs. If a trans-
verse section of the thorax is made, it will be noticed that the pleure do °
not come into contact, and that there is a distinct space between them
extending from before backward (Plate 41, Fig. 2). This is called the
interpleural space, and is subdivided into the anterior, middle, and pos-
terior mediastina. Of these the middle is the largest compartment, and
contains the heart within the pericardium, the vessels which pass to and
from the base of the heart, the phrenic nerves, and the bifurcation of the
trachea and the bronchial lymphatic glands. The anterior mediastinum is
in front of the pericardium, and, as it is first exposed upon opening the
thorax anteriorly, it has already been described (page 259), as being in
the natural order of approaching the study of this region. The posterior
mediastinum is behind the pericardium, between it and the dorsal vertebre,
from the fourth to the twelfth, and contains the descending thoracic aorta,
the csophagus, the pneumogastric nerves, the vene azygos major and
minor, the thoracic duct, and lymphatic glands (Plate 38).

The lungs are two large spongy organs within the pleure, occupying
during life the whole of the cavity of the thorax on each side of the
mediastinum, and separated from each other by the heart enclosed in the
pericardium. They vary even in health from a pale-pinkish color to a
mottled gray, depending upon their vascularity and inflation. With age
they generally become darker and spots are visible upon their surface,
probably due to the deposition of particles of carbonaceous matter which
have been inhaled. After death they usually appear of a dark-purple
hue, especially at the back, in consequence of venous stagnation. When
the lungs are fully distended, as in forced inspiration (Plate 30), they will
be seen to conform to the shape and limitation of their respective pleura.
Each lung has a rounded apex, which extends into the root of the neck
(Plate 27) two and a half centimetres, or about an inch, within the pleural
264 THE REGION OF THE THORAX.

domes (page 262), and a concave dase, which conforms to the arch of the
diaphragm upon which it rests. They fit into the pleural sinuses when
fully expanded, and reach downward posteriorly as far as the eleventh rib
on each side,—the right lung in the axillary line being in relation to the
ninth rib, and the left lung to the tenth rib.

The right lung is thicker and shorter than the left, the concavity of
its base being also higher, as it corresponds to the arch of the diaphragm
over the liver. It is often notched on its mediastinal surface, presenting
depressions for the superior and inferior vene cave. The left lung is
excavated on its mediastinal surface for the reception of the heart, and
its apex has an impression for the left subclavian artery. The apex ‘of
the left lung does not mount quite so high above the clavicle as does that
of the right. The anterior edges of both lungs present characteristic differ-
ences. That of the right lung is nearly straight or vertical, and that of
the left is oval or oblique. The extent to which they approach each
other depends upon the degree of their expansion. In forced inspiration,
when the lungs are absolutely healthy, the anterior edges of the lungs
meet over the root of the heart and the origin of the great vessels
within the pericardium (Plate 30). The surfaces of the pleure are
thus brought into contact to the extent of several inches, between the
lower border of the manubrium sterni and the junction of the cartilages
of the fourth ribs with the sternum. At such times the anterior edge of
the right lung is absolutely vertical and parallel with the median line of
the chest, and the area of the heart which is uncovered by the left lung
is limited to the lower third of the right ventricle. In ordinary tranquil
breathing the anterior edges of the lungs do not come together (Plates 31
and 32). Ina state of collapse both lungs shrink back into their recesses
within the thoracic cavity (Plate 33).

From careful observations made upon both the living and the dead
body at different ages, it would seem to the author that only when healthy
do the lungs meet in front over the root of the heart upon a profonged
and full inspiration. There is generally some interspace between them in
the anterior mediastinum. The right lung comes forward more readily
than does the left, even in moderate inspiration, so that the anterior ‘edge
THE REGION OF THE THORAX. 265

of the right lung approaches more nearly the middle line. The lower
portion of the right lung also expands more readily below in relation to
the diaphragm than does the lower portion of the left lung, whereas the
converse appears to be true with regard to their apices. Not only does the
left lung not come forward so readily, but its lower portion does so only
upon prolonged inspiration, and thereby reaches the anterior limit of its
pleural sac. When both lungs are normal and fully inflated in the well-
developed adult male, in the erect position, the lower front edge of the
right lung corresponds approximately to the oblique line of the interspace
between the cartilages of the sixth and seventh ribs (Plate 27), while the
lower front edge of the left lung is in relation to the lower border of
the seventh rib, and extends but a little way beyond the sternal end of
that rib (Plate 30). These limitations will be lessened by the breadth
of a rib if the individual be placed in the recumbent position, and in
the female or poorly-nourished youth they may be lessened still more,
so that the anterior lower edges of the right and left lungs may reach
respectively the lower borders of the fifth and sixth ribs, corresponding
to the height which the arches of the diaphragm normally reach and
hold relatively (page 322) to each other. It should be therefore under-
stood that in respiration the upper portions and posterior surfaces of the
lungs are at all times in close contiguity with their pleural sacs, and that
the anterior medial and lower edges retire and advance according to the
effort of expiration or inspiration and the healthy condition of the pleure
which allows their natural freedom of motion. It is very doubtful if the
anterior lower edges of the lungs ever do completely fill their proper
portions of the pleural cavities, and an adhesion existing anywhere be-
tween the lung and its sac will influence the degree of motion of the lung.
In forced expiration the lower edges of the lungs posteriorly do not ascend
higher than the lower borders of the seventh ribs. A transverse section
made across the root of the neck from the first dorsal vertebra to the top
of the sternum (Plate 14, Fig. 1) will show that the apex of the right
lung is larger than that of the left, and that they are both in this locality
of oval form. A transverse section across the thorax from the eighth

dorsal vertebra to the lower borders of the third ribs (Plate 41, Fig. 2)
34
PLATE 838.

The posterior mediastinum and its contents, as seen on removal of the dorsal vertebre (from the second to the
ninth) with portions of their contiguous ribs. The lungs are expanded so as to show their proper relations posteriorly.

1. The body of the first dorsal vertebra. 9, The thoracic duct, after its entrance into the thorax
2. The thoracic duct, winding across the cesophagus to from the aortic opening.

enter the superior mediastinum. 10. The upper surface of the left arch of the diaphragm.
3. The upper portion of the left lung. 11. The spine of the ninth dorsal vertebra.
4. The descending portion of the arch of the aorta, over- | 12. The upper portion of the right lung.

lapped above by the left lung. 13. The vena azygos major entering the superior vena cava.
5. The vena azygos major, crossing to the right of the | 14. The left auricle of the heart.

cesophagus. 15. The lower portion of the right iung.
6. The ceesophagus, distended. 16. The base of the left ventricle of the heart.

7. The vena azygos minor. \ 17. The inferior vena cava. _
8. The thoracic aorta. ! 18. The upper surface of the right arch of the diaphragm.
 

 

 

Me. Crectan, M D,

 

sectad, Photographed and Colored from Nature ty Geor'
Armstrong & Co Lith Boston

 

 
THE REGION OF THE THORAX. 267

shows that both lungs are here somewhat palm-shaped, with their bases
toward the spine and their narrower portions toward the sternum.

Each lung is divided into an upper and a lower lobe by a great jissure
which commences behind about seven and one-half centimetres, or three
inches, from the apex, opposite the fourth dorsal vertebra on the right and
the third on the left, and descends obliquely forward to the junction of the
seventh rib with its cartilage on the right, and opposite the sternal end of
the sixth rib on the left. There are, however, many alterations in the
relative positions of the fissures, and their terminations cannot be foretold.
There is generally a deep notch in the anterior edge of the left lung over
the pericardium where it is in relation to the apex of the heart (Plate 30,
No. 42), and occasionally the right lung is similarly notched about the
cartilage of the fourth rib (Plate 29). The right lung is subdivided by
a secondary fissure which commences about opposite the sixth rib, near its
angle, and extends usually to the cartilage of the fourth rib and thus
marks off a middle lobe. The lower primary lobes‘of both lungs are the
largest, and they chiefly constitute the posterior portions, whereas the
anterior portions are mainly formed by the upper lobes. Occasionally
the left lobe has a semblance of a secondary fissure, and occasionally
also the secondary fissure in the right lung is undeveloped.

The convex outer surfaces of the lungs are free and moulded to the
interior of the thoracic walls, and the concave inner or mediastinal
surfaces are connected to the heart and the trachea by the bronchial
tubes, with their vessels, nerves, and lymphatics, and by the pulmonary
arteries and the pulmonary veins. These structures collectively form the
roots of the lungs, and are held together by areolar tissue, and supported
below by reflections of the pleure, called the ligamenta lata pulmonalia.
The roots of the lungs are attached to the bottom of a deep cleft, the hilum
pulmonale, which is situated a little nearer the posterior than the anterior
surfaces and above the middle of each lung. If the thorax be opened
from behind by removing the dorsal vertebree and contiguous portions of
their ribs (Plate 39), it will be seen that the vena azygos major arches over
the root of the right lung and the aorta over the root of the left lung.
Behind the right root are the posterior pulmonary plexus of the pneumo-
268 THE REGION OF THE THORAX.

gastric nerve and the vena azygos (Plate 37), and behind the left are the
descending aorta and the posterior pulmonary plexus of the pneumogas-
tric nerve (Plate 36). In front of each root are the anterior pulmonary
branch of the pneumogastric and the phrenic nerve. In front of the
root of the right lung is also the superior vena cava (Plate 33).

The trachea at the root of the neck, as previously described (page 236),
passes deeply from the outer surface in front of the csophagus to its
bifurcation into the right and left bronchi within the superior mediastinum.
The bifurcation is about on a level with the body of the, fourth dorsal
vertebra posteriorly, and opposite the second intercostal space anteriorly.
Within the chest the trachea is crossed by the arch of the aorta, the deep
cardiac nerves passing between them. The cesophagus projects a little
to the left of the middle line at the root of the neck, and is closely con-
nected by areolar tissue to the trachea, which is placed between the upper
portions of the two pleure. The recurrent laryngeal nerves from the
pheumogastric nerves ascend on each side of the neck in the grooves
between the trachea and the cesophagus (Plate 39).

The bronchi vary in length, direction, and diameter. The right
bronchus is about two and a half centimetres, or an inch, in length, and,
passing nearly horizontally, enters the right lung about opposite the body
of the fifth dorsal vertebra. Its diameter is greater than that of the left
bronchus, and, as the ridge of separation between the two bronchi at the
bottom of the tracheal tube inclines to the left of the middle line, foreign
bodies which may chance to fall down the trachea are more likely to pass
into the right bronchus. The Jdefé bronchus is about five centimetres, or two
inches, in length, and descends obliquely to enter the left lung opposite the
sixth dorsal vertebra. The left bronchus passes in front of the cesophagus
and thoracic duct,and under the arch of the aorta (Plate 38). In struct-
ure the bronchi resemble the trachea (page 236), the right having from six
to eight rings and the left from nine to twelve. At the roots of the lungs
the bronchi subdivide into two branches, the bronchial tubes, corresponding
to the primary lobes of the lungs. The lower branch of the right bronchus
sends off a small branch to the third lobe on that side. The right bronchus
at the root of the right lung is behind the right pulmonary artery, and
THE REGION OF THE THORAX. 269

the left bronchus also holds the same relative position, being behind the
corresponding pulmonary artery. On both sides the pulmonary veins
are in front of the arteries (Plate 41, Fig. 1). Within the lungs the
bronchial tubes divide dichotomously into posterior and anterior branches,
which again subdivide into lateral branches, and these diverge in all direc-
tions throughout the organs until their termination in the lobules, where
they are known as dbronchiolés. There is no communication between the
bronchioles, so that if any obstruction occurs in one branch the air cannot
reach the vesicles to which it naturally leads.

The pulmonary and bronchial vessels, the lymphatics and nerves, all
accompany the ramifications of the bronchial tubes, and are united to them
by connective tissue, the arteries always being behind and the veins in
front of the tubes. Within the structure of the lungs the tubes cease to
have regular cartilaginous rings, circular muscular fibres with patches of
cartilage here and there constituting the walls of the branches. They are
lined throughout with the mucous membrane continued from the trachea,
which is covered with columnar ciliated epithelium. Gradually all traces
of cartilage disappear and the walls present irregular dilatations, which
commence in pouches surrounding the ultimate tubules. These enlarge
in diameter and end as sacculated passages, the infundibula, whose walls
consist of blind pouches, the alveoli or air-vesicles. They are surrounded
and connected everywhere with an elastic tissue, in which there are only
slight traces of muscular tissue, and which is derived from the peculiar
elastic sub-serous tissue closely investing the surfaces of the lungs beneath
the pleura. Upon this elastic tissue the remarkable expansibility of the
lungs depends. When the chest is opened the lungs collapse to about a
third of their ordinary bulk (Plate 33), in consequence of their elasticity.
This elastic tissue is prolonged from the surfaces into the inner structure of
the organs, forming numerous angular spaces of various sizes about the
alveoli, and called the pulmonary lobules: When the lungs are distended,
the surface is everywhere marked by polygonal areas, which vary in size at
different ages. These areas are mapped out into smaller ones, which are
less distinct. They indicate the lobules, which are larger on the surface
than in the interior of the lung. After air has once entered into the
270 THE REGION OF THE THORAX.

lobules it cannot be entirely pressed out, owing to their spongy texture,
and any portion of the lung will therefore float on water, but it will sink
immediately if inspiration has not taken place, and owing to this property
such a demonstration is frequently made use of as a test in medico-legal
investigations. It should be remembered that a portion of lung-tissue from
which the air has been dispelled by pneumonic exudation will also sink
in water. When pressed between the fingers, the escape of air from the
lung-tissue produces crepitation. When the air-vesicles are ruptured, the
air escapes into the interlobular tissue, producing pulmonary emphysema,
and if there is infiltration of serum into this tissue it is called edema of
the lung. If the lung-tissue is torn, a reddish frothy liquid is exuded,
consisting of mucus, air, and blood commingled.

The terminal branches of the pulmonary artery form nets of capillary
vessels which accompany the bronchioles in their distribution to the alveoli,
where they are covered by epithelium on both surfaces and project into
the air-vesicles. The pulmonary capillaries are very crowded in relation
to the air-vesicles, and the plexus surrounding one air-vesicle is arranged
in a single layer and has no communication with that of another vesicle.
There are only the delicate wall of the vesicle and the walls of the capil-
lary vessels between the blood and the air, so that the purification of the
blood takes place through the absorption of the oxygen and the elimination
of carbonic acid and watery vapors. The blood circulating through the cap-
illary plexuses is returned by the pulmonary veins, which are very minute
at first, but gradually coalesce so that they form branches of increasing
calibre and size, which freely anastomose, and, following somewhat the
course of the arteries, eventually terminate at the root of each lung in two
main trunks which convey the oxygenated blood to the left auricle of the
heart. There are no valves in any of the pulmonary veins. Besides the
pulmonary system of vessels there are the nutrient vessels of the lungs, de-
rived from the small bronchial arteries. On the right side there is usually
one bronchial artery, which arises either from the first aortic intercostal or
from the aorta in common with the left bronchial artery. On the left side
there are usually two bronchial arteries, both arising from the aorta. They
enter at the roots of the lungs posterior to the bronchi, and are distributed
THE REGION OF THE THORAX. 271

to the walls of the tubules, the larger pulmonary vessels and the pulmonary
lymphatic glands, and the inflections of the elastic interlobular tissue.

The bronchial veins mostly empty on the right side into the vena
azygos major, and on the left into the superior intercostal vein, although
some of them empty their blood into the corresponding pulmonary veins.

The pulmonary lymphatic vessels are very numerous, and are arranged
in superficial and deep sets, the former forming plexuses over the surface
(sub-pleural lymphatics) and throughout the interlobular tissue, communi-
cating with the cavity of the pleura by stomata, and the latter beginning
in the mucous lining of the bronchial tubes and accompanying the vessels.
The deep lymphatic vessels terminate in the pulmonary lymphatic glands,
which are situated along the walls of the smaller bronchial tubes and in
the angles of their divisions. There are about forty in the right lung and
thirty in the left. The efferent vessels from these pulmonary glands join
with the superficial lymphatic vessels and end in the bronchial glands which
are clustered about the roots of the lungs and the lower portion of the
bronchi and trachea. The efferent vessels from the bronchial glands com-
municate with the mediastinal glands, and are generally blackened by the
deposition of carbonaceous matter. The right pulmonary lymphatics pass
through the intermediation of the mediastinal glands to the right lymphatic
duct, and the left pulmonary lymphatics join the thoracic duct.

The pulmonary nerves are derived from the pneumogastric and sympa-
thetic nerves on each side, which form the anterior and posterior pulmo-
nary plexuses in front of and behind the roots of the lungs. They enter
the lungs with the bronchial tubes and accompany their ramifications.

The pericardium, or heart-sac (Plate 34, and Plate 26, Fig. 1), is a
dense fibrous pouch which encloses the heart and the portions of the
great vessels which enter into and issue from its base. It is broadest
below in relation to the diaphragm (page 320), where it is intimately
adherent to the middle leaflet of the tendon about the opening for the
inferior vena cava and more loosely connected to the muscular part on the
left side. Above it passes into the superior mediastinum, enveloping the
great vessels and becoming continuous with their sheaths. In this relation
it also blends with the downward prolongations of the deep cervical fascia
gous

10.

11.

12.
13.

14.

PLATE 89.

View of the thoracic organs from behind, the dorsal vertebre (from the second to the tenth) with portions of their
contiguous ribs removed. The lungs are displaced to show the relations of the heart.

. The body of the first dorsal vertebra.

The left subclavian artery.
The upper (cut) part of the thoracic duct ascending to
empty into the left subclavian vein.

. The left common carotid artery.

The left recurrent laryngeal nerve.
The left innominate vein.

. The arch of the aorta.
. The left phrenic nerve.
. The left lung pushed aside and forward to show the po-

sition of apex of the heart resting on the diaphragm.

The thoracic aorta, with origins of the intercostal ar-
teries.

The apex of the left ventricle of the heart within the
pericardium.

The vena azygos minor.

The lower (cut) end of the thoracic duct coming through
the aortic opening of the diaphragm.

The upper surface of the diaphragm on the left side.

 

15.

23.

24.
25.
| 26.
27.
28.

The innominate artery, bifurcating into the right com-
mon carotid and subclavian arteries.

. The right internal mammary artery.

. The vena cava superior.

. The upper (cut) end of the cesophagus.

. The right pneumogastric nerve.

. The right phrenic nerve.

. The vena azygos major, emptying into the superior

vena cava.

. The bifurcation of the trachea into the right and left

bronchi.

The right lung pushed aside and forward to show the
relation of the left auricle of the heart and the arch
of the diaphragm on the right side.

The left (or posterior) auricle of the heart.

The position of the inferior vena cava.

The upper surface of the diaphragm on the right side.

The lower (cut) end of the cesophagus.

The spine of the tenth dorsal vertebra.
9 Von I

ee
Q
+
®
Wo

 

 

 

 

 

 

Copyneht /89/by GeorseMc.l

ssacted, Photogravhed and Colored trom Nature by Georse Me, Creccan, M 2. emeiona se GALRIBOSTae
THE REGION OF THE THORAX. 273

(page 195), which are continued as dense bands (the suspensory ligaments)
upon each side to their attachment at the diaphragm. These connections
of the pericardium are of great interest, for if the entire diaphragm descends
in respiration it must draw with it the heart-sac and therefore exert more or
less strain upon the vessels at the base of the heart. The author inclines
to the belief that the central portion or tendon of the diaphragm does
not descend, although the lateral muscular portions do. On one occasion,
after the excision of the sixth, seventh, and eighth ribs on the right
side, he was able to examine the upper surface of the diaphragm during
the forced efforts of inspiration under ether, and on another, after the
evacuation of the contents of an enormous abscess involving the left lobe
of the liver, he could easily introduce his hand into the abscess-cavity
and detect the lateral upheaving of the diaphragm and the rapid pulsa-
tions of the heart. In the latter case, during the straining of the patient
in the act of vomiting it was observed that the diaphragm descended
and ascended with spasmodic contractions, but only upon the sides, there
being apparently little if any change in the relations of its central
tendon. There can be hardly any doubt that the direct connections of the
pericardium below with the central tendon of the diaphragm and with the
expansions of the deep cervical fascia above play an important réle in
maintaining the position of the arch of the aorta, and thus admitting of
sudden changes of position without injurious interference with the circu-
lation of the blood at its outset from the heart. The slight descent of
the larynx noticeable on deep inspiration is probably due to the expansion
of the chest walls and the consequent lateral traction exerted upon the
bronchi by the distended lungs. The pleure overlap the pericardium
in front, the right more so than the left (Plate 26, Fig. 1), and the phrenic
nerves descend between them upon each side. Posteriorly the cesophagus
is in close relation with that part of the pericardium which encloses the
left auricle of the heart. After death the pericardium usually appears
to be considerably larger than the heart, but this is due to the empty
condition of the left side of the heart. In the healthy state, when the
heart is distended, during life, it nearly fills the -pericardium, except at

the lower part on the left side of the diaphragm, where the sac covers
85
274 THE REGION OF THE THORAX.

the apex of the heart and is more or less loose. Although the pericardium
is not ordinarily distensible, it may be made in the adult to hold about
ten ounces of fluid, and in. pericarditis with effusion the accumulation of
serous fluid within the sac sometimes reaches a pint or more, which may
be drawn off by tapping through the fourth or fifth interspace two cen-
timetres, or about three-quarters of an inch, from either border of the
sternum, so as to avoid the internal mammary vessels. The pericardium
ordinarily contains several drachms of a clear straw-colored fluid.

The nutrient arteries to the pericardium are derived from the internal
mammary, bronchial, and cesophageal arteries, and its veins mostly return
their blood to the vena azygos. Its nerves are supplied by the phrenic
nerves on both sides. If the pericardium is opened in front (Plate 35)
the heart will be exposed glistening with the moist surface of a serous
tissue which is reflected over it and the vessels at its base and also lines
the fibrous sac. This serous tissue forms a shut sac, and is composed of
a parietal layer in contact with the fibrous pericardium and a visceral layer
in contact with the heart and interposed between the vessels so as to form
a series of pouches. The invagination of the serous layer over the vessels
is not always to the same extent, but there are usually seven tubular
sheaths thus formed. There is a common reflection around the aorta and
pulmonary artery, completely ensheathing them. The superior vena cava
is also covered by the serous layer, except where it crosses behind the pul-
monary artery. The inferior vena cava is covered only in front as it enters
the right auricle directly after passing through the diaphragm. The left
pulmonary veins are almost surrounded, and the right are only partially
covered. The reflection of the serous layer is very irregular. The pouch
which extends upward from the inferior vena cava on the right to the
posterior surface of the left auricle is called the great oblique sinus.
There are other, smaller pouches,—7.e., between the inferior vena cava and
the inferior right pulmonary vein, between the pulmonary veins, one on
each side, between the upper right pulmonary vein and the superior vena
cava, and one between the superior vena cava and the aorta, which, pass-
ing under the aorta and pulmonary artery, reaches the left side over the
left auricle. This last, from its direction, is called the transverse sinus.
THE REGION OF THE THORAX. 275

Besides these there is a fold between the left pulmonary artery and left
pulmonary vein, of crescentic shape, two and a half centimetres, or about
an inch, in depth, and two centimetres, or three-quarters of an inch, in
length, which is the vestigial fold, and is the remains of the left superior
vena cava of early foetal life. These serous reflections enable the heart
and the vessels at its base to maintain their freedom of action. That
portion of the visceral layer of the pericardiac serous tissue which is
closely connected with the intermuscular tissue of the heart-structure
is distinguished as the epicardium. There are upon the surface many
stomata which open from the plexus of lymphatic vessels, especially along
the auricular margins. This layer also contains the nutrient vessels and
nerves, which are usually associated with more or less fat along the grooves
and deeper parts of this tissue. Even in health the amount of fat deposited
upon the heart is often considerable; but this must not be confounded with
the more serious condition of fatty degeneration of the muscular tissue.
The heart, as it appears upon opening the pericardium (Plate 35), is
conical in form, and its surfaces are generally convex, with the exception
of that portion which rests upon the pericardium where it is attached to
the central tendon of the diaphragm, and which is flattened. It is situated
obliquely as regards the middle line of the chest. Its base, to which
the great vessels are attached, is directed upward and backward to the
right side, where it is held firmly in relation to the spine between the
fifth and ninth dorsal (thoracic) vertebrae by means of the dense cervico-
thoracic fascia, which blends with the pericardium at the roots of the
great vessels. Elsewhere the heart is free within the pericardium, and
its apex is directed downward and forward to the left side, where during
life it generally beats in relation to the interval between the fifth and
sixth costal cartilages. The anterior surface of the heart consists mainly
of the right auricle and right ventricle, which are brought into view
when the pericardium is opened in front. The termination of the superior
vena cava is also thus exposed as it enters the right auricle above, at
the side of which is the ascending portion of the aorta curving upward
and backward over the pulmonary artery, the root of which is over-
lapped by the appendix of the left auricle. Below the latter are the
276 THE REGION OF THE THORAX.

branches of the left coronary artery passing toward the apex of the
heart in the groove between the left and right ventricles. On the
right side the right coronary artery issues from beneath the appendix of
the right auricle, which overlaps the root of the aorta. The apex is
formed by the left ventricle, which projects a little beyond the right, so
that normally its beat is felt against the chest wall. The posterior surface
“of the heart is formed chiefly by the left auricle and the left ventricle
(Plate 48, Fig. 3).

As the relative position of the heart to the walls of the thorax is
chiefly of value with reference to the normal location of the cardiac valves,
it is thought best here to refer to the anatomy of the heart removed from
the body (Plate 43), in order that a clearer idea may be obtained of
the topographical survey of its relations im situ. The exterior of the heart
presents more or less defined grooves which indicate the division of its
interior into the four compartments called the auricles and ventricles.
The auriculo-ventricular groove passes obliquely around the heart between
the auricles and the ventricles. The interauricular groove separates the
two auricles, and the interventricular groove separates the two ventricles,
the anterior portion of the latter beginning under the left auricular
appendix and ending to the right of the apex. The nutrient vessels,
nerves, and lymphatics to the heart are chiefly lodged in these grooves
embedded in fatty tissue beneath the epicardium, as already mentioned
(page 275). The right coronary artery arises from the aorta upon the
right side just after it issues from the heart-structure, and, passing between
the pulmonary artery and the right auricle in the auriculo-ventricular
groove, distributes branches to the contiguous vessels and portions of the
right auricle and ventricle. The left coronary artery arises from the back
of the aorta, a little higher than the right, and, passing between the
pulmonary artery and the left auricle in the auriculo-ventricular groove,
gives off several large branches which occupy the interventricular grooves
and anastomose freely with the branches of the right coronary artery upon
the outer surface. Within the substance of the organ the minute divisions
of the coronary arteries terminate in capillary plexuses which empty into
comparatively large venous radicles. It is an interesting fact that the
THE REGION OF THE THORAX. 277

origin of both coronary arteries is above the free borders of the aortic
semilunar valves, the right being from the anterior sinus of Valsalva and
the left from the left posterior sinus, so that there is a steady passage of
the blood through them. The coronary veins receive their blood from
the cardiac veins, which accompany the arteries and are provided with
single valves where they are joined by their tributaries. They all end
‘in the coronary sinus, which is two and a half centimetres, or about an
inch, in length, situated at the back part of the auriculo-ventricular
groove, and opens into the floor of the right auricle between the opening
of the inferior vena cava and the auriculo-ventricular orifice. At its
entrance into the auricle it is guarded by the coronary valve.

The shape of the heart varies during life, according to its dilatation or
diastole, and its contraction or systole, but its vertical measurement is not
altered by its action. The dimensions of the heart naturally vary with the
age, sex, and general development of the individual. The average meas-
urement of the heart of a well-developed adult male is twelve and a half
centimetres, or about five inches, in length, from the base to the apex, eight
and three-quarter centimetres, or three and a half inches, across the base,
and six and a half centimetres, or about two and a half inches, in thick-
ness, between the anterior and posterior surfaces. As a rule, the dimen-
sions of the heart increase up to the age of fifty, and subsequently gradually
diminish. The weight is generally about ten ounces in the male, and eight
in the female, but depends upon the size and general condition of the body.
The right border (margo acutus) is sharp and directed obliquely downward,
while the left border (margo obtusus) is thick and rounded and directed
obliquely upward. From the front of the right auricle a small pouch pro-
jects about the root of the aorta, which is called, from its resemblance to
the ear of a setter dog, the appendix auricule, and from the upper side of
the left auricle a similar appendix extends over the root of the pulmonary
artery. When the adult heart is opened so as to display the interior of its
cavities (Plate 43, Figs. 2 and 4) it appears to be a double hollow mus-
cular organ, so constructed that each half, separated from the other by a
septum, fulfils the function of a pump, for the propulsion of the blood in its
circulation. The right half of the heart propels the venous blood to the
278 THE REGION OF THE THORAX.

lungs, the left propels the arterial blood throughout the body. Each half
consists of two cavities, the auricle and the ventricle, communicating by
an opening, the awriculo-ventricular, which is peculiarly guarded by valves.
The auricles are the receptacles of the blood, and are provided with com-
‘paratively thin fleshy walls, which are always slightly thicker in the left
than in the right. The ventricles, on the other hand, are composed of
stout muscular walls adapted to their purpose of forcing outward the blood
received from the auricles, their thickness being proportioned to the effort
required of them. The left is therefore naturally thicker and stronger,
as it distributes the arterial blood throughout the system, while the right
sends the venous blood to the lungs. The right auricle consists of a main
cavity, the atrium or sinus venosus, out of which extends the pouch called
the appendix. When the anterior wall is removed the interior is exposed
smooth and glistening, because it is lined with a delicate serous membrane,
the endocardium, which is continuous with the serous coat of the vessels
opening into the auricle, and through the opening into the ventricle below
with the inner lining of the pulmonary artery. The opening of the supe-
rior vena cava is in the upper and anterior part of the auricle, about
opposite the right auriculo-ventricular opening, so that the current of
venous blood which it conveys from the upper part of the body is directed
immediately to the ventricle. The orifice of the superior vena cava is
the only large cardiac opening without a valve. The opening of the
inferior vena cava is in the lowest part of the auricle, and, owing to
the slight curve which the vessel takes after passing through the dia-
phragm, the venous blood which it returns from the lower part of the
body is directed toward the oval depression, the fossa ovalis, in the auric-
ular septum. The fossa ovalis indicates the position of the foramen ovale,
which during fcetal life allowed the blood from the inferior vena cava
to pass through into the /eft auricle. At that period this course of the
blood was greatly assisted by the presence of the Hustachian valve, which
is situated at the right margin of the opening of the inferior vena cava
and extends to the front of the annulus ovalis, the prominent border
surrounding the fossa. In the adult this valve appears as a thin
erescentic fold of the endocardium, and often it has dwindled into a
THE REGION OF THE THORAY. 279

mere rudimentary band, simply indicating its former position. The
floor of the fossa ovalis is the thinnest part of the septum between the
auricles.

Between the remains of the Eustachian valve and the auriculo-
ventricular opening is the entrance of the coronary sinus, which is quite
large and is guarded by a duplicature of the endocardium, called the
valve of Thebesius. Besides the sinus there are a variable number of
little openings on the posterior wall of the auricle, called the foramina
Thebes, which are the minute apertures of little veins coming from the
heart-substance. Some of these are impervious, but one, situated on the
right of the septal wall, is constant, and known as the vena Galeni cordis.
Interposed between the openings for the superior and inferior vene cave
there is a variable elevation termed the tubercle of Lower, which prob-
ably aids in the direction of the blood from the superior cava toward
the auriculo-ventricular opening in embryonic life. Within the auricular
appendix, and to some degree in the lower part of the atrium, there are
parallel elevations of the muscular tissue covered with the endocardium,
called, on account of their resemblance to the teeth of a comb, musculi
pectinati.

The right auriculo-ventricular opening is of oval form, and large
enough to admit three fingers. It is guarded by the tricuspid valve, which
is named from the usual tripartition of the fibrous tissue of which it is
composed, and invested by the endocardium ; but this arrangement is often
less pronounced than it is generally described as being. When the anterior
wall is removed from the right ventricle, the objects within its cavity are
exposed (Plate 43, Fig. 2). At the upper part there is a smooth passage
leading to the opening of the pulmonary artery, called the infundibulum,
or conus arteriosus. From the walls of the ventricle, which are every-
where thicker than those of the auricle, project bands of muscular tissue,
the columne carnee, of various character and arrangement. Some are
short and thick, others are long and narrow. ‘They are either mere
ridges projecting from the walls, or constitute little bridges, having both
ends attached and being free in the middle. There is usually a band
extending from the ventricular septum to the anterior wall, called the
SCHOnNraunr WW

n

PLATE 40.

The normal position and relations of the thoracic aorta, seen from behind, the lungs being removed to show their
roots.

. The body of the first dorsal vertebra.

. The left subclavian artery.

. The left innominate vein.

. The left internal mammary artery.

. The left common carotid artery.

. The arch of the aorta.

. The left first rib.

. The left phrenic nerve.

. The vertebral border of the scapula.

. The left recurrent laryngeal nerve winding upward

round the aorta.

. The left second rib, near its cartilage.

. The left third rib.

. The root of the left lung.

. The left fourth rib.;

. The left fifth rib.

. The apex of the left ventricle of the heart (within the

pericardium),

. The upper surface of the diaphragm on the left side.
. The position of the aortic opening in the diaphragm.
. The right subclavian artery.

 

20.
21,
22,

30.
31.
382.

33.
34.
35.
36.

37,

The innominate artery.
The upper (cut) end of the cesophagus.
The right internal mammary artery.

23. The superior vena cava.
24.
25. The trachea bifurcating into the right and left bron-

The right recurrent laryngeal nerve.

chi.

26, The right second rib.
27.
28.
29.

The right pneumogastric nerve.

. The root of the right lung.

. The right third rib.
The left auricle of the heart.
The right fourth rib. *
The thoracic aorta, with the roots of the intercostal
arteries.

The inferior vena cava.

The right fifth rib.

The upper surface of the diaphragm on the right side.

The lower (cut) end of the esophagus, where it passes
through the diaphragm.

The spine of the tenth dorsal vertebra.
late 40

acted, Photograph

 

2

Colored trom Nature by Georce Mc. CLettan, M D,

Cooyreht/89/.by

 

SEORGE Mo CLeLL ANMD.

 

Von L

Armstrong & Co Lith Boston,

 

 
THE REGION OF THE THORAX. 281

moderator, or a number of reticular fascicles taking its place, which pre-
vents the complete reflection of the anterior wall.

The most important of the columne carnee are those which are called
the musculi papillares. There are three of these, usually well formed, in
the right ventricle, corresponding in number to the flaps of the tricuspid
valve. They are attached by one end to the walls of the cavity, and at
the other terminate in the fine tendinous cords, the chorde tendinee,
which regulate the action of the tricuspid valve. The two largest of the
papillary muscles arise from the anterior wall of the ventricle, and the
smallest from the septal wall. Occasionally accessory fasciculi are found
interposed between the regular muscles and blending with them.

The auriculo-ventricular opening is surrounded by a ring of fibrous
tissue which constitutes the base of the valve. The flaps of the valve
are thinnest at their contiguous margins where they receive the chorde
tendinee. Not unfrequently the edges of the flaps are jagged and
irregular, and sometimes in the notches between them there are little
projecting nodules. The flaps are designated according to their relative
position as right and left anterior and posterior. The left anterior flap
is the largest and freest, while the posterior is the shortest and least
movable and is placed toward the septum. The chorde tendinew which
are attached to the adjacent margins of the right and left anterior flaps
and to the notch between them are furnished by the anterior papil-
lary muscle; those to the adjacent margins of the right anterior and
posterior flaps and to the intervening notch come from the posterior
papillary muscle; and those to the adjacent margins of the left anterior
and posterior flaps and to the intervening notch come from the smaller
papillary muscle, which is derived from the septal wall and often aug-
mented by independent chords which spring from the septum without
any papillary muscle. The mode of attachment of the chorde tendine
to the flaps is of peculiar interest, as they serve to hold together the
flaps of the valve during the systole of the ventricle and thus prevent
the blood from regurgitating into the auricle. They are all fastened
to the ventricular surface of the valve, and they severally separate inte

branches which go respectively to the base, middle, and free margins
86
282 THE REGION OF THE THORAX.

of the adjacent borders of the flaps as above described. Further-
more, the component fibres of the cords interlace with one another in the
fibrous tissue of the valve. In the empty state of the ventricle the
flaps appear hanging downward from the auriculo-ventricular opening,
but experiment has shown that when the ventricle is full of fluid and is
made to contract the fluid catches in the margin of the valve and presses
the flaps upward and together, while the chorde tendinee act like little
guy-ropes and prevent the flaps from turning upward into the auricle.
Their proper adjustment and tension are brought about by the action
of the papillary muscles, for without them they would be naturally
slackened by the contraction of the walls of the ventricle.

At the upper part of the right ventricle the infundibulum leads into the
common pulmonary artery, the mouth of which is guarded by three semi-
lunar valves, of which one is situated anteriorly to the left and two are
placed posteriorly to the right and left. At the upper and posterior surface
of each valve the wall of the artery is dilated in a pouch, the pulmonary
sinus (of Valsalva). The valves are formed of fibrous tissue continuous
with the fibrous ring surrounding the opening, similar to the construction
of the base of the auriculo-ventricular valve, and covered with a duplica-
ture of the endocardium. The free margins of the valves are directed
upward toward the lumen of the artery, and are each provided with a cres-
centic fibrous border, the dunula, in the middle of which there is a little
blunt nodule of fibro-cartilage, called the corpus Arantw. The semilunar
valves are readily forced upward by the blood during the ventricular
systole, but when the ventricle relaxes the blood in the artery backs up
against the valves, and, being received into the sinuses, exerts pressure
upon the lunule of the valves, so as to bring them together, their closure
being completed by the apposition of the nodules.

The deft auricle is smaller than the right, but, like it, consists of a cavity,
the sinus, and the auricular appendix. When the posterior wall is removed
(Plate 43, Fig. 4) the interior of the sinus is seen to be covered with the
endocardium, which is continuous with the lining membrane of all the
openings leading in and out of the auricle, and through them with the
internal coats of the vessels. Upon the posterior wall of the auricle are the
THE REGION OF THE THORAX. 283

openings of the pulmonary veins, usually four in number, two on the left
and two on the right side, which return the oxygenated blood from the
lungs. Sometimes the left pulmonary veins open by one orifice, more
rarely by three. They are not guarded by valves. Upon the inter-
auricular septum is a depression which indicates the position of the
foramen ovale of foetal life, which before birth admitted the venous blood
brought by the inferior vena cava to the right auricle into the left auricle
The musculi pectinati of the left auricle are fewer and smaller than in the
right auricle, and are confined to the lower and back part of the cavity.
The left auriculo-ventricular opening is of oval shape and a little smaller
than the right, and is placed at the lower and anterior part of the auricle.
It is guarded by the bicuspid or mitral valve, which has two flaps, one
anterior and to the right, and one posterior and to the left, with little nodules
projecting at their notches, called the nodi valvule mitralis. The right flap
is the larger. The interior of the left ventricle presents a close resem-
blance to the right. Its walls are very thick, especially in their upper
portion, where they are also broadest, but they gradually diminish toward
the apex. The columne carnee are smaller, more reticulated, and more
numerous than in the right ventricle. Two large, variably-constituted
papillary muscles project from among the columns at the bottom of the
cavity, the anterior from the left wall and the posterior from the right.
They terminate in chorde tendinew, which are attached to the flaps of
the mitral valve. The construction of the mitral valve corresponds to
that of the tricuspid valve, but it is thicker and stronger in all its com-
ponent parts. The ring of fibrous tissue surrounding the auriculo-ven-
tricular opening, the flaps themselves, and the chorde tendinee are all
stronger. The latter are similarly attached to the adjacent margins of
the flaps, the posterior papillary muscle supplying the adjacent margins
on the right, and the anterior papillary muscle furnishing the adjacent
margins on the left. They are both reinforced by additional cords from
the contiguous portions of the walls with or without muscular origin. The
action of the mitral valve is apparently the same as that of the tricuspid,—
ie., to prevent regurgitation of the blood into the auricle during the systole
of the ventricle. From the upper and back part of the left ventricle a
284 THE REGION OF THE THORAX.

smooth surface leads to the opening into the aorta, which resembles that
of the pulmonary artery, having three semilunar valves, with dilatations of
the aortic wall (sinuses of Valsalva) behind them. The aortic opening is
placed in the groove between the two auricles, and it is very close to the
left auriculo-ventricular opening, being separated from it only by the
larger anterior flap of the mitral valve. In framework and construction
the aortic semilunar valves differ from those guarding the pulmonary
artery only in being proportionately stronger, to adapt them to the
greater work they have to accomplish, consistently with the greater
strength of the left ventricle, in sending the arterial blood throughout
the general system.

The structure of the heart consists of an intricate arrangement of layers
of muscular fibres supported upon a framework of fibrous tissue. The
latter is disposed in rings about the two auriculo-ventricular, the aortic,
and the pulmonary openings, as described in their proper relations. These
rings, besides forming the bases for the attachment of the valves, receive
at their external circumference the muscular fibres of the walls of the
different cavities. The strongest part of the fibrous skeleton is in the inter-
space between the aortic and the two auriculo-ventricular openings. This
is triangular, and in some of the lower animals is substituted by a bony
nodule, called the os cordis. The muscular fibres of the heart are peculiar
for the comparatively small amount of connective tissue between the
component fascicles, which are of the striped variety and very closely
associated. They are arranged in layers, whose striee pass transversely and
longitudinally. The fibres of the auricles are distinct from those of the
ventricles. They consist of a superficial layer, which generally runs across
the base of the heart, including both auricles, and a deep layer, composed
of fibres surrounding the auricular appendix and the entrances of the vene
cavee on the right.auricle, and the auricular appendix and the entrances of
the pulmonary veins on the left. The superficial fibres are most marked
on the anterior surface, and send a few fasciculi inward to the interauric-
ular septum. The deep fibres also blend with the muscular fibres of the
ventricles in front and behind the auriculo-ventricular fibrous rings. The
layers of fibres composing the walls of the ventricles are very complicated,
THE REGION OF THE THORAX. 285

and can be satisfactorily studied only after hardening by prolonged boiling,
which dissolves the connective tissue. These fibres are independent of the
auricles, and are much thicker. They consist of various layers, which for
the most part commence from the rings of the fibrous framework above
and descend obliquely to the apex of the heart, twisting upon one another
in such a manner as to produce what is called the vortex, and ascend in
the interior of the walls back again to the fibrous rings, sending off in their
courses fibres which constitute the columne carne and musculi papillares.
The most superficial layer of the ventricular fibres in front of the heart
descends obliquely across from right to left, many of those from the
right at the anterior interventricular groove turning inward and intersect-
ing with the fibres in the ventricular septum which arise from the deeper
layers. Behind the heart the fibres descend from left to right, and do not
enter at the posterior interventricular groove. The deeper layers of fibres
which compose the chief bulk of the ventricular walls are arranged in |
strata, whose fascicles vary in the degree of their obliquity, diminishing
from without inward, and interlacing everywhere, so that they present
fibres which have been described as making annular or figure-of-eight
loops. Some of the deeper layers of fibres do not appear to have any
connection with the fibrous rings. The most valuable inference to be
drawn from the laborious efforts of investigators, who have attempted to
unravel the complications of these muscular fibres, is that the musculi
papillares are integral parts of the walls from which they spring, so that
they contract simultaneously with them.

The nerves of the heart are derived from the pneumogastric and from
its recurrent branch, and from the three cervical sympathetic ganglia on
both sides (page 219), which form the great cardiac plexus in front of
and behind the arch of the aorta. This consists of numerous, minute,
and delicate nerves, which interlace in every direction with one another,
and are known, from their relative position, as the superficial and deep
cardiac plexuses. (Plates 36 and 37). In relation to the concavity of the
aortic arch there is sometimes found a small ganglion (the cardiac ganglion
of Wrisberg). Both the superficial and deep cardiac nerves form frequent
connections with each other, and thus establish the pulmonary pleauses
PLATE 41.

Figure 1.

The thorax of a young female, with the second, third, fourth, fifth, and sixth ribs removed on the left side, and the
left lung drawn aside to show the relations of the root of the lung and the apex of the heart to the diaphragm.

1. The manubrium of the sternum.
2. The cartilage of the left second rib.

3. The left internal mammary artery with its two com-

panion veins.
. The cartilage of the left third rib.
. The cartilage of the left fourth rib.
. The cartilage of the left fifth rib.
. The left first rib.
. The upper lobe of the left lung.
. The root of the left lung.

CONDO

10.
1,
12.
18,
14,

15.
16.
17.

The left phrenic nerve.

The coronary artery.

The lower lobe of the left lung.

The apex of the heart.

The relation of the phrenic nerve to the apex of the
heart.

The diaphragm.

The left seventh rib.

The diaphragm seen between the left eighth and ninth
ribs.

Figure 2.

Transverse section through the thorax of an adult male, on a level with the lower borders of the third ribs anteriorly
and through the body of the eighth dorsal vertebra posteriorly, seen from below.

1. Section through the gladiolus of the sternum.
2. The right internal mammary vessels.
3, The anterior mediastinum.

4, Section through the right third rib.

5. The superior lobe of the right lung.
6. The right ventricle of the heart.

7. The right auricle of the heart.

8. Section through the right fourth rib.

. The right phrenic nerve.

10, The middle lobe of the right lung.

11, Section through the right fifth rib.

12, The cesophagus.

13. The vena azygos major.

14, The inferior lobe of the right lung.
15. Section through the right sixth rib.
16. Section through the right seventh rib.
17, The right eighth rib.

a]

 

. Spine of the eighth thoracic vertebra.

. The left internal mammary vessels.

, The anterior margin of the superior lobe of the left lung.
. The superior lobe of the left lung.

. The left ventricle of the heart.

. The left phrenic nerve.

. Section through the left fourth rib.

Section through the left bronchi.

. The left pneumogastric nerve.
. The thoracic duct.

The descending aorta.

. The inferior lobe of the left lung.

The body of the eighth thoracic vertebra.

. The spinal canal with section of the spinal cord.
. The eighth thoracic vertebra.
. The left eighth rib.

Section through the dorsal muscles.
yOL

late 41 VC

 

Copyright, /89/ by GeoreeMc Cietan,M.D.

tad. Photographed and Colored from Nature 6 Georce Mc. Creiian, MD,
Armstrong & Co, Lith. Boston

 
THE REGION OF THE THORAX. 287

in relation to the roots of the lungs, and the coronary plexuses. The
branches of the latter respectively accompany the ramifications of the
coronary arteries both without and within the substance of the heart. It
is said that there are minute inéra-cardiac ganglia, which possibly preside
over the functional contractions of the heart.

The lymphatic vessels of the heart, which also occupy for the most
part the interventricular grooves with the vessels and nerves, convey their
lymph to the glands situated between the aorta and the trachea, and thence
pass to the right lymphatic duct and the thoracic duct on either side of
the root of the neck.

The superior vena cava (Plate 35) is formed by the right and left
innominate veins (page 222), which unite opposite the first intercostal
space on the right of the border of the sternum, and descends, with a
slight inclination backward, to the right auricle, which it enters at its
upper and anterior part, opposite the third right costal cartilage. It is
six and a quarter centimetres, or about two and a half inches, in length, in
the adult, and the lower portion is covered with the pericardium (Plate 34).
Above it is covered on the right side by the pleura, between which and
the great vein the phrenic nerve passes downward. The superior vena
cava is without valves, and receives, besides some pericardiac and medi-
astinal veins, the vena azygos major, which curves downward over the
right bronchus above the pericardium (Plate 37, No. 30).

The aorta (Plates 33, 35, 36, 40, 42, and 43) arises opposite the
lower border of the third costal cartilage, at the upper and posterior part
of the left ventricle, near the centre of the heart. Its normal course is very
singular, and its shape much resembles that of an old-time shepherd’s crook.
At its commencement it is expanded into a bulbous enlargement, in con-
sequence of the dilatations (the sinuses of Valsalva) opposite the semilunar
valves at its cardiac orifice, and proceeds upward about five centimetres, or
two inches, and a little to the right of the middle line, as high as the lower
border of the second right costal cartilage. This portion is called the
ascending (or ventral) aorta, and is enclosed in the fibrous layer of the
pericardium. It is in very close relation with the under surface of the
sternum, the lower margin of the thymus gland and the right pleural sac
288 THE REGION OF THE THORAX.

being interposed between them. The bulbous enlargement is covered by
the pulmonary artery on the left, being included with it in a common
sheath of the serous layer of the pericardium, and by the appendix of the
right auricle on the right (Plate 35). The ascending aorta encroaches some-
what upon the superior vena cava, and is in relation posteriorly to the right
pulmonary vessels and the root of the right lung. The coronary arteries
to the heart are given off from the origin of the aorta, as already described
(page 276). Near the termination of the ascending portion the aorta
usually presents a dilatation, the sinus maximus, which changes the lumen
of the vessel in that situation from circular to oval. It is worthy of
especial note that the first or ascending part of the aorta is closely covered
only by the thin serous layer of the pericardium, which renders an aneu-
rism in this locality very dangerous, in consequence of the easy, rapid
distention of* the coats of the vessel and the slight hinderance to the
escape of the blood into the pericardium.

From the lower border of the second right costal cartilage the aorta
passes backward, at first a little upward and to the left, toward the body
of the second dorsal vertebra, and then, curving across the trachea just
above its bifurcation, it turns downward at its left side as far as the
lower border of the fourth dorsal (thoracic) vertebra. This portion is
called the transverse aorta, or arch of the aorta. Its relations are very
important and interesting. On the left it is overlapped by the left pleura,
beneath which the left phrenic nerve passes, and it is in close proximity to
the left pneumogastric nerve, which here gives off the left recurrent laryn-
geal nerve (Plates 386 and 40), which curves upward under, the aorta (page
186). On the right it is in contact with the right pleura, and posteriorly
it is very near the trachea, cesophagus, and thoracic duct. From the upper
surface of the arch of the aorta the three normal branches arise close
together,—.e., the innominate artery (page 221), the left common carotid
artery (page 223), and the left subclavian artery (page 229). Their
origins are crossed by the left innominate vein (Plate 35). The orifices
of the innominate and the left common carotid, when examined from within
the aorta, are separated by merely a sharp edge. The cardiac nerves from
the sympathetic and pneumogastric nerves also pass over the arch to their
THE REGION OF THE THORALY. 289

distribution on the heart (page 219). This portion of the aorta measures
four and three-quarter centimetres, or a little less than two inches, in
length. The highest point to which its convex surface reaches in a well-
formed adult is usually about two and a half centimetres, or an inch, below
the upper border of the sternum, and its concavity corresponds with the
ridge between the manubrium and the gladiolus; but these points cannot
be definitely relied upon, as various factors may tend to raise or lower the
arch, and it is subject to modifications owing to interference with its proper
development.

There are various irregularities of the great vessels which probably
occur more frequently than has been noted, and may be ascribed to either
an arrest or a persistence of one or other of the primitive aortic arches
of early embryonic life, out of the ordinary order of the human develop-
ment. Such modifications usually result in transposition of the innomi-
nate to the left side or some change in the point of origin of the carotid or
the subclavian artery upon one or both sides. Anomalies of the heart
and the aorta are extremely rare. It may not be inappropriate to mention
in this connection such a case which the author met with in the body of
a man aged twenty-seven years, whose death was caused by phthisis.
The preparation (Plate 26, Fig. 4) exhibits no arch of the aorta, but
independent origins of both right and left carotid and subclavian arteries
from the top of the descending thoracic aorta, with the heart placed
vertically, the position in which it was found within the chest. This
disposition of the aortic branches is somewhat analogous to that ordina-
rily observed in the horse and in the ruminating animals, but it does not
appear to have been hitherto recorded as found in man. The heart was
found to consist of a single auricle and a single ventricle.

The common pulmonary artery (Plate 35), which conveys all the
venous blood from the right side of the heart, to be aerated in the lungs,
commences at the infundibulum in the upper part of the right ventricle
(page 279). This vessel is nearly five centimetres, or two inches, in
length, and, as has been already stated, is contained within the sheath
of the serous layer of the pericardium, which is common to it and the
ascending portion of the aorta. It stands out in front of all the great
290 THE REGION OF THE THORAX.

cardiac vessels when the heart-sac is opened between the right and left
auricular appendages (Plates 33 and 35). Its direction is upward and
backward to the concavity of the arch of the aorta, where, in front of the
bifurcation of the trachea and on a level with the sixth dorsal vertebra,
it divides into the right and left pulmonary branches, which, passing
through the pericardium on each side, enter the roots of the respective
lungs. The right branch is larger and longer than the left, and is separated
from the arch of the aorta by the deep cardiac nerves of that side, and
as it enters the root of the right lung it is in front of and delow the right
bronchus (page 268). The left branch passes in front of the descending
aorta and enters the root of the left lung in front of and above the left
bronchus (page 269). Where the left branch leaves the pericardium
there is a short fibrous cord extending backward to the left end of the
arch of the aorta, which is the remains of the ductus arteriosus, the canal
‘by which, in fcetal life, the blood from the pulmonary artery passed
directly into the aorta (page 304). The pulmonary veins, which return
the blood to the left auricle of the heart after it has been re-oxygenated
and transformed into arterial blood in the lungs, commence in a net-work
of capillary vessels upon the walls of the air-vesicles, where they are con-
tinuous with the ultimate ramifications of the pulmonary artery (page
270). They also receive part of the blood distributed by the bronchial
veins in the substance of the lungs. They unite at first into single
trunks corresponding to each lobule, and these in turn unite to form a
trunk for each lobe, so that the right lung has three and the left lung
two main efferent vein-trunks. Usually the two upper trunks of the
right lung join at its root, although they sometimes remain independent
of each other. The right pulmonary veins are somewhat longer than the
left, and they all terminate in the posterior wall of the left auricle
(page 283), the orifices of those coming from the left lung being closer
together and on a lower level than those from the right. The upper
one of the right and the lower one of the left are respectively larger
(eighteen millimetres, or three-quarters of an inch, in diameter) than
their companion veins. Both pairs in the roots of the lungs (page 268)
occupy a position in front of the pulmonary arteries, and as they pass
THE REGION OF THE THORAX. 291

horizontally toward the left auricle they pierce the pericardium, the
serous layer of which is reflected over their anterior surface. There are
no valves in the pulmonary veins.

As the heart is the central organ of the vascular system, in which,
by means of the great vessels at its base, the arteries originate and the
veins terminate, the general anatomy of these two classes of the blood-
vessels may be here properly considered.

The arteries are comparatively firm, elastic tubes, which commence
at the heart in two great trunks, the aorta (page 287) and the pulmonary
artery (page 289), the former distributing the arterial blood from the
left ventricle throughout the general system, and the latter conveying
the venous blood from the right ventricle to the lungs, as described
on page 306.

The systemic arteries arise from the main branches of the aorta, which
are directed to the head and the extremities and to the various organs
of the body. The arteries generally pursue the shortest, most direct, and
most protected course from their origins to the locality of their distri-
bution, and this is particularly noticeable in the extremities, where they
are contiguous to the bones, in the lines of flexure, so that they are less
exposed to injury and less likely to be compressed by muscular action.
The arteries (except within the tissues of the brain and of the bones)
are provided with a special investment of the areolar tissue of the parts
in which they are contained, constituting their sheaths, and in particularly
exposed situations the superficial arteries are usually further protected by
tendinous expansions. They also continue of uniform size until they give
off a branch, when they become, as a rule, somewhat smaller in calibre.
It has been estimated, however, that the combined capacity of the branches
is greater than that of their original trunks, and in consequence there is
naturally a diminution in the velocity of the blood-current as it proceeds
farther and farther from its source. In certain localities, where the parts
are freely movable, the arteries are tortuous, so that they readily accom-
modate themselves to changes in position and the movements of the soft
parts without being subjected to strain. The facial, lingual, and vertebral
arteries are examples. Arteries branch in various ways. If they divide
292 THE REGION OF THE THORAX.

into two equal branches, they diverge at equal angles, from the line of the
trunk. If the branches are unequal, the trunk is deflected from its
straight course to the side opposite that to which the branch is distributed,
varying in degree according to the size of the branch. In fact, the
branches may be given off at any angle, but they usually proceed at an
acute angle from their origin. In their course the smaller arteries fre-
quently communicate with one another, constituting what is called their
imosculation or anastomosis. This arrangement serves to prevent an inter-
ruption in the flow of the blood in case of pressure upon one or other of
the branches, and is of great value in the establishment of the collateral
circulation after the ligation of any one of the principal vessels.

In the brain, the retina, and the kidneys the ultimate branches of
the arteries are called ¢erminal or end arteries, because they do not anas-
tomose with one another, and consequently if a supplying artery is blocked
by an embolus the area of its distribution is completely destroyed by
necrosis.

During life the arteries possess a considerable degree of elasticity
and contractility, as is often witnessed in the remarkable manner in which
they escape injury in penetrating and incised wounds. In the healthy
state the walls of the arteries are capable of withstanding a considerable
degree of intravascular tension, and their firmness is conspicuous, for when
they are cut across they do not collapse, as the veins do. They appear
empty after death, and on this account were originally supposed to contain
air. The elasticity of the arteries diminishes with age, and in consequence
they often become spirally twisted and tortuous in localities where they are
loosely embedded in the tissues. The size of the arteries is proportionate
to the amount of blood required by the physiological actions of the part
which they supply. The larger arteries (eight millimetres, or three-eighths
of an inch, in diameter) are attended by a single large vein; the medium-
sized arteries (six millimetres, or one-quarter of an inch, in diameter)
have one or two accompanying veins, and the smaller (three millimetres, or
one-eighth of an inch, in diameter) usually two veins. The vene comites
of the arteries are generally included in their areolar sheath, together with
the nerve-cord which passes-to the same area of distribution as the artery.
THE REGION OF THE THORAX. 293

The course of the arteries in the extremities is generally along the inter-
muscular septa, or in the spaces between the superficial and deep muscles, so
that a twig issuing among the surface-tissues, if traced backward, serves as a
guide to the position of the main vessel. By this means, for example, the
anterior and posterior tibial arteries within the deeper part of their course
may be easily found; and there is no safer way of reaching the external
iliac artery than by following the deep epigastric, or of reaching the
axillary artery than by following the acromial. Owing to some localized
arrest of development, occasioning dilatations of anastomotic branches and
attended by contraction or obliteration of the main trunk, there are fre-
quent variations in the arteries, and it often happens that a vessel which
is usually small may become abnormally enlarged, so that it is liable to
be mistaken for the main artery. It should be remembered also that a
small branch arising from a large vessel will always bleed freely, and
to an extent out of proportion to its size, so that its hemorrhage requires
to be promptly arrested.

The structure of the walls of the arteries consists of three chief layers
of various formation which are intimately associated with one another.
They are called the external, middle, and internal coats, or the tunice
adventitia, media, and intima. The external coat, or adventitia, on which
the strength and firmness of the arteries mainly depend, is composed of
layers of condensed fibro-connective tissue derived from the surrounding
cellular tissue and arranged in interlacing bundles, between the meshes
of which are lymph-spaces and connective-tissue corpuscles. In the larger
vessels, and in the arteries which are loosely connected with their sur-
roundings, as on the face and the mesentery, longitudinal muscular fibres
are blended with the other elements of the outer coat, which in the latter
case not only renders the mesenteric arteries thicker but enables them to
offer support to the parts which they supply, the jejunum and the ileum,
and to withstand the constant traction to which they are subjected in the
changes of position of the intestines during life. The middle coat, or
media, is the thickest portion of the wall of an artery. It consists princi-
pally of unstriped muscular fibres (and therefore is sometimes also called the
muscular coat), with a variable quantity of elastic connective-tissue fibres.
PLATE 42.

Dissection of the vascular system in a child eight months old, showing the principal arteries and veins in their
proper relations and positions.

 

1, The right temporal artery. 38, The insertion of the sartorius, gracilis, and semitendi-
2, The right facial artery. nosus muscles,
3. Branch of the right lingual artery. 39, The left temporal artery.
4, The body of the hyoid bone. 40. The left facial artery.
5. The superior, or descending, thyroid artery. 41, The left lingual artery.
6. The right internal jugular vein. 42, The left sterno-mastoid muscle.
7. The right common carotid artery. 43. The left pneumogastric nerve.
8. The right pneumogastric nerve. 44, The left internal jugular vein.
9. The median nerve of the right arm. 45. The left common carotid artery.
10. The thyroid body. 46. The left superior thyroid artery.
11. The sternal end of the right clavicle. 47, The median nerve and brachial artery of the left arm.
12. The axillary artery. 48, The axillary artery, surrounded by the cords of the
18. The trachea, at the root of the neck. brachial plexus.
14, The right subclavian vein, branching from the right | 49. The sternal end of the left clavicle.
innominate vein. 50. The left carotid artery.
15. The right innominate vein. 51. The left innominate vein.
16. The right subscapular vessels and nerves. 52. The left subclavian artery. :
_ 17. The superior vena cava. 58. The left subscapular vessels and nerves.
18, The root of the right lung, showing the pulmonary ves- 54. The arch of the aorta.
sels. 55. The root of the left lung, showing the pulmonary vessels.
19. The right auricle of the heart. 56. The posterior coronary artery.
20. The anterior coronary artery and veins. 57. The apex of the heart.
21. The under surface of the diaphragm, showing the right | 58. The left phrenic artery, on under surface of the dia-
phrenic arteries. phragm.
22. The inferior vena cava. 59. The abdominal aorta,
23. The right kidney, opened, showing the renal vessels. 60. The ceeliac axis.
24, The right spermatic vein, emptying into the inferior | 61. The left kidney, opened to show the renal vessels.
vena cava. 62. The left spermatic vein, emptying into the renal vein.
25. The superior mesenteric artery, drawn to the right | 63. The left ureter.
side. 64. The left spermatic artery.
26. The right ureter. 65. The left internal iliac artery.
27. The right coinmon iliac artery. 66. The inferior mesenteric artery.
28, The right spermatic artery. 67. The sigmoid flexure of the colon, drawn aside.
29. The right internal iliac artery. 68, The superior hemorrhoidal, or rectal, artery.
30. The inferior mesenteric artery. 69, The left circumflex iliac artery.
31. The right circumflex iliac artery. 70. The bladder.
32, The right anterior crural nerve. 71. The left anterior crural nerve.
33. The right femoral vessels, passing under Poupart’s 72. The left femoral vessels.
ligament. 73. The left spermatic cord.
34, The right spermatic cord. 74, The left adductor longus muscle.
35. The sartorius muscle. 75. The left sartorius muscle.
36. The femoral artery, passing into Hunter’s canal. 76. The left gracilis muscle.
37. The gracilis muscle. ‘77, The anastomotica magna. artery.

N. B.—The preparation from which the photograph for this plate was taken is remarkable because it is an actual
demonstration of the circulation of the blood. The injection, a solution of wax in ether, was introduced into the right
common carotid artery beneath the lobe of the thyroid body, and, having passed through the capillaries, filled the veins.
There is some probability that the foramen ovale had remained unclosed, which would have contributed to complete
the venous injection. The ductus arteriosus was obliterated.
 

Copyright /890,by Georce Mc CLeLtan, M.D.
THE REGION OF THE THORAX. 295

They are arranged for the most part circularly, except in the smallest
arterioles, where they are spiral. The proportion of the elastic tissue
apparently diminishes with the size of the artery, while the converse is
true with regard to the muscular tissue, so that the smaller vessels possess
greater contractility relatively to the larger. Connective tissue also enters
into the construction of this coat in the larger vessels, and many of the
latter are provided with an external elastic lamina (Henle). The muscle-
fibres in the middle coat of the large arteries are irregular and both oblique
and longitudinal, while in the small arteries they are more uniform and
exhibit under the microscope longitudinal striee each containing an elliptical
nucleus. The wmternal coat, or intima, is very delicate and thin, and com-
posed of an intermixture of elastic and fibrous tissue arranged in several
layers. The amount of elastic tissue also varies with the size of the vessel,
being in the smallest merely a single layer. The internal surface of
the intima consists of the transparent membrane, the endangiwm, which
closely resembles the serous membranes in character and is continuous
with the endocardium of the heart. The endangium has been demonstrated
to be constituted of two layers, called the endothelium and the membrana
propria. The former consists of a single stratum of transparent fusiform
cells having a central nucleus and arranged parallel to the course of
the vessel. The latter consists of interlacing connective-tissue fibres con-
taining branching corpuscles. The amount of muscle and elastic tissue
in the walls of certain arteries is variable irrespective of their calibre,
as it has been proved that the carotid and axillary arteries are provided
with more elastic tissue in their middle coats than the femoral, which has
a greater quantity of muscle-fibre.

Upon the application of a ligature to an artery in the healthy state
the internal and middle coats are completely broken, so that they retract,
while the external coat is puckered up.

The arteries are without valves.

The veins possess much thinner walls and are generally larger in
calibre than the arteries. They return the venous blood from the system
by means of the superior and inferior venee cave (pages 287 and 306), and
from the walls of the heart by the coronary sinus (page 277), to the right
296 - THE REGION OF THE THORAX.

auricle, and the arterial blood from the lungs by the pulmonary veins
(page 290) to the left auricle. The systemic veins are more numerous than
the arteries, and their combined capacity is greater. They originate in
radicles, which receive the blood from the capillaries everywhere in the
tissues, and are generally arranged in plexuses at their commencement.
From these plexuses branches are given off which unite into trunks, which
are constantly increased in size by being joined by tributaries in their
course toward the heart. They consist of two chief divisions, the swper-
Jicial and the deep veins. 'The former are placed between the layers of the
superficial fascia beneath the skin, and the latter accompany the arteries,
being known as the vene comites, or satellites. The largest arteries and
their largest branches are usually accompanied by a single vein, but the
medium-sized and smaller arteries have two veins, which are enclosed in
their common sheaths, as previously described (page 292). In certain
regions, as in the brain, the spinal canal, and the liver, the veins do not
accompany the arteries; in others, as in the head and face, they pursue a
more direct course than the arteries. The veins communicate or inoscu-
late much more freely than the arteries do, even among those of large
size. This is conspicuous with the superficial veins, which form a net-
work over the whole body. The intercommunication of the superficial
veins with the deep is especially noticeable at the flexures of the joints,
where the motions would otherwise be liable to offer impediment to the
flow of the blood. This is also markedly the case in the neck and within
the cranium, where any obstruction to the venous system would be followed
by a dangerous stasis.

The veins of the dura mater within the head are called the sinuses,
which are formed by the splitting of that membrane and lined by
epithelium (page 18). In certain localities where veins are contained
within masses of areolar tissue and enveloped in a dense fibrous membrane,
they may anastomose, but as their walls are imperfect they allow their
blood to escape into the surrounding trabecule or spaces and thus form
erectile tissue, as in the corpora cavernosa penis. The veins offer very
many anomalies, but there is always a noticeable fact regarding them,—
z.¢., that where a vein is unusually small there is a compensating enlarge-
THE REGION OF THE THORAX. 297

ment in an adjoining or neighboring vein. Such a variation is commonly
noticed between the external and anterior jugular veins (page 192). The
structure of the walls of the veims is composed, like that of the arteries, of
three coats, but taken together they are less uniform and thinner than the
arteries, although they are more intimately connected. They possess con-
siderable strength, however, and the walls of the superficial veins are
generally thicker than the deeper ones. It is very difficult to separate
the eaternal and middle coats. The former consists chiefly of a compact
layer of fibro-connective tissue blended with meshes of elastic fibres.
The latter is mostly made up of irregular circular bands of unstriped
muscular tissue, also held together in meshes of elastic fibres. The
amount of fibro-connective and muscular tissue varies in the veins of
different parts, and the two tissues hold variable proportions to each
other in the outer and middle coats. In the great jugular and innomi-
nate veins at the root of the neck there is a deficiency of muscular
tissue. In the Haversian canals of the bones the walls of the veins con-
sist only of fibrous tissue lined with endothelium.

The internal coat, or intima, of the veins is very similar to that of the
arteries, consisting of a very delicate elastic membrane, having upon its
internal surface an endothelial lining and a substratum of striated con-
nective tissue, often containing muscle-cells. One of the most important
peculiarities of the veins is the development of valves from their internal
coats in certain localities, which prevent regurgitation of the blood and
therefore assist its passage toward the heart. They usually occur in pairs,
placed opposite each other in the course of a vein, but are single at the
orifices of the branches. The valves are not found in all veins, but they
are most numerous in the superficial veins of the extremities, especially the
lower, where they often appear like knots through the skin in varicosed
conditions. They consist of crescent-shaped flaps composed of the inner
coat, like little pockets. They are attached with their convex border to
the sides of the vein and their free concave margin directed in the
proper course of the blood, so that if this is interfered with by pressure
and a reflux occurs the pockets become filled and close the lumen of the

vein by their distention. The valves are not always equally developed,
88
298 THE REGION OF THE THORAX.

as on several occasions the author has found it possible to throw ax
injecting material into the radicles of the hand or foot through the main
venous channel of the limb: in two instances a solution of wax in ether
was thus made to traverse the capillaries and fill the arteries.

The relative position which the main arterial and venous trunks bear
to one another throughout the body follows the rule already mentioned
(page 222), that above the diaphragm the veins are superficial to the
arteries, while below the diaphragm the arteries are superficial to he
veins, with the single exception of the renal veins.

The capillaries are the fine hair-like vessels which serve as ‘the secret
communications by which the blood passes continually from the arteries
into the veins throughout the tissues of the various organs of the body.
They are so minute that they can be seen only with the microscope, and
so fine that it is necessary to rupture several of them to get a drop of
blood. Although generally very numerous, they vary in number in the
different tissues according to their requirements for nutrition, being most
abundant in the tissues or organs where the greatest degree of vital activity
exists. They are not found in the cartilages, epithelium, or epidermis.
Ordinarily they are arranged in a system of net-works, which vary in
the size of their meshes in different localities. They are very close
in the lungs, in the gray substance of the brain and spinal cord, in the
mucous membranes generally, and in the muscular and adipose tissues.
In the dermis and choroid coat of the eye the net-work of capillaries is
exceedingly fine and close. In the fascie, however, and the aponeuroses,
tendons, and ligaments, the capillary meshes are wider, the vessels them-
selves being fewer. They are variably arranged to conform with the
structure of the tissues which they occupy. This is noticeable especially in
the lungs in relation to the lobules, and in the papille of the skin or the
villi throughout the intestinal canal. In their simplest form the capillaries
may be considered as composed only of the delicate endothelial lining of
the arteries or veins with which they are continuous. They are both elastic
and contractile, so that they differ in calibre under different conditions.
Under the influence of chemical reagents their walls have been shown to
have a cellular construction, with the cells arranged longitudinally to the
THE REGION OF THE THORAX. 299

axis of the vessel. The cells contain an oval nucleus, and they are held
together by what is termed “intercellular cement,” which is marked at
intervals by fine dots. During the state of inflammation the capillaries
become distended, and the intercellular cement in the localities of these
dots yields, occasioning small openings in the walls, the stomata, through
which the white blood-corpuscles show a tendency to escape into the inter-
spaces among the tissues. This is an important characteristic of these
vessels, as by its means the elements of nutrition in the processes of growth,
repair, and performance of function are imbibed and eliminated. When
the capillaries in the web of a frog’s foot or in the mesentery of a snake are
examined under the microscope, they appear as transparent tubes contain-
ing a clear fluid (quor sanguinis), which moves more slowly along the
walls of the vessels, being retarded by friction, than in the centre, where
the corpuscles are arranged in a column and are swept onward with greater
rapidity. It follows from the resistance offered by the increased wall-area
of the capillaries, as well as by the minuteness of their lumina, that the
blood circulates through the capillaries much more slowly than it does in
the large arteries. In some tissues the blood-vessels, before they terminate
in capillaries, divide into peculiar tufts of minute anastomosing vessels,
such as are seen in the glomeruli or Malpighian corpuscles of the kidney.
In others the separate arterial stems and venous radicles form a net-work
before they break up into capillaries, and thus constitute the different forms
of rete mirabile, such as occur in the choroid tela and velum interpositum
of the brain. The walls of all the larger arteries and veins are provided
with arteries and veins of their own, the vasa vasorwm, which are derived
from and terminate respectively in the neighboring vessels. It is evident
to the naked eye that such vessels are furnished to the external coats of the
large vessels, and it is asserted that the microscope has revealed that there
are capillary vessels in relation also to the middle coat. Lymphatic vessels
appear, as already stated, in and around the external coats, and about the
largest vessels they establish plexuses.

The arteries and veins are also supplied with nerves, the vaso-motor
nerves, which form plexuses in the muscular or middle coats, more
especially of the arteries. They have been shown to preside over the
300 THE REGION OF THE THORAX.

contractility and dilatability of the vessels, and explain many of the
physiological phenomena, as in pallor or blushing, and the changes in
local temperature, owing to their influence upon the degree of blood-
pressure. The vaso-motor nerves, although apparently derived as fibres
from the sympathetic ganglia in the various regions of the body, have
been demonstrated by experiment, in many instances, to arise originally
from the nerves of the spinal cord. The so-called inhibitory or repressing
effect manifested in the physiological action of certain drugs is probably
ascribable to them. ‘These nerves are now considered as consisting of two
distinct sets of fibres, which from their opposing influences are called vaso-
constrictor and vaso-dilator nerves. ‘The marvellous rapidity with which
the secretion and excretion of certain organs are performed, and the regu-
lation of the distribution of the blood by which the various physiological
processes of digestion are determined, can be understood only by taking
into account the controlling influence of this special division of the intri-
cate nerves, composed of fibres from the sympathetic and fibres from the
spinal nerves combined, and probably presided over by some special centre
in the floor of the fourth ventricle of the brain.

The blood is the viscid, red-colored, opaque, alkaline fluid which
circulates throughout the vascular system, -and the function of which
is to furnish the nutritive material to all the tissues and organs of the
body, and to eliminate from them many of the elements of waste which
are capable of being revivified and used over again. The color of the
blood varies according to the conditions under which it is seen, and in
the different sets of vessels in which it flows, being bright red in the
arteries, and bluish-black or purple in the veins. These changes of '
color are due to the amount of oxygen which is in combination with the
hemoglobin, the coloring-matter of the blood. The blood has a saline
taste and a peculiar odor. Its material is in a continual state of change
and motion, the degree of the latter being regulated by the influence of
the vaso-motor nerves and the calibre of the vessels in which it is contained.

The blood consists essentially of cellular elements, the corpuscles, and
an intercellular substance, the plasma. The corpuscles are of two kinds,
the white, or leucocytes, which are variable in number in different parts
THE REGION OF THE THORAX. 301

and in different conditions of the individual, and the red corpuscles, which
in health always greatly outnumber the white and give to the blood its
characteristic color. The leucocytes are colorless, nucleated cells, which
under the microscope show amceboid motions. The red corpuscles are
uniform, homogeneous, flattened circular disks, concave upon both surfaces
and without nuclei. There are also in the blood a quantity of minute
oval disks, called bdlood-plates, and numberless granules, hematodlasts.
The plasma is a clear, colorless, alkaline fluid, which is capable of trans-
udation through the walls of the capillary vessels into the surrounding
cellular spaces of the connective tissue. These spaces are now called
lymph-paths, because the lymph is formed within them as the result of
the combination of unused plasma and waste tissue-cells. The lymphatic
system of vessels is described with the lacteals, in connection with the
anatomy of the intestinal canal, in Vol. IT.

When fresh blood is examined at the temperature of the body, the
white corpuscles are seen to change slowly their shape and position, re-
sembling in many respects the microscopic animalcule the ameba. This
power of ameboid movement enables the white corpuscles under certain
influences to pass out with the plasma into the cellular spaces; and hence
these corpuscles are also known as the migratory cells. The white
corpuscles are in fact derived from the lymph, and are supposed to be
‘the source of the red corpuscles; but this has not yet been satisfactorily
established. The red corpuscles in fresh blood exhibit a remarkable
tendency to pile themselves together like little rouleaux of coin. The
plasma consists chiefly of a permanent liquid, the serwm, which is a straw-
-colored fluid, and of certain elements called fibrin-factors, fibrinogen and
fibrino-plastin. When the blood is withdrawn from the body and at
rest, there is apparently a ferment formed from the breaking down of
some of the white corpuscles, which occasions the union of the fibrin-
factors into a clot, or coagulum. The serwm is an albuminous solution
containing salts, fatty matters, sugar, etc., and readily coagulable by heat.
The blood also contains in solution oxygen, carbonic acid, and nitrogen
gases. The hemoglobin, or coloring-matter, belongs to the red corpus-
cles, and has a remarkable affinity for oxygen, which it absorbs when
PLATE

Figure

— 48.

1.

The front view of the heart removed from the body, with the roots of the great vessels arising from the aorta.

The left subclavian artery.

The left common carotid artery.

The transverse portion of the arch of the aorta.
The descending portion of the arch of the aorta.
The common pulmonary artery.

The appendix of the left auricle.

The left coronary artery.

The right ventricle.

The left ventricle.

The apex of the heart.

2

Section of the right auricle and ventricle to show the interior of their cavities.

The right common carotid artery.

The right subclavian artery.

The transverse portion of the arch of the aorta.

The descending portion of the arch of the aorta.

The appendix of the left auricle.

The pulmonary artery laid open.

The semilunar valves.

The cut edge of the right ventricle.

The anterior musculus papillaris.

A bristle passed through the right auriculo-ventricular
opening.

The chorde tendinez.

The inter-ventricular septum.

The columne carnez.

The apex of the heart.

3.

The posterior view of the heart in relation to the thoracic aorta.

1. The trachea, ML.
2. The ima thyroidea artery. 12.
3. The right common carotid artery. 18.
4. The right subclavian artery. 14.
5. The innominate artery. 16.
6. The superior vena cava. 16.
7. The ascending portion of the arch of the aorta. 17.
8. The right coronary artery. 18,
9. The right auricle. 19.
10. The appendix of the right auricle. 20.
Figure
1, The ima thyroidea artery. 16.
2. The right common carotid artery. 17.
3. The right subclavian artery. 18.
4. The innominate artery. 19.
5. The ascending portion of the arch of the aorta. 20.
6. The superior vena cava. 21.
7. The foramina Thebesii. 22,
8. The opening of the vein of Galen. 23.
9, The annulus ovalis. 24.
10. The fossa ovalis. 25.
11. The tubercle of Lower.
12. The Eustachian valve. 26.
13. The orifice of the coronary vein. We
14, The musculi pectinati. 28.
15. The inferior vena cava. 29.
Figure
1. The left common carotid artery. 9.
2. The left subclavian artery. 10.
3. The descending portion of the arch of the aorta. 11.
4, The pulmonary artery. 12.
5. The appendix of the left auricle. 13.
6. The posterior coronary artery.
7, The thoracic aorta, 14,

8, The apex of the heart.

Figure

The right common carotid artery.

The right subclavian artery.

The transverse portion of the arch of the aorta.

The superior vena cava.

The dilatation situated at the entrance of the inferior
vena cava into the right auricle.

The inferior vena cava.

4.

The posterior wallsof the left auricle and ventricle removed to show the interior of their cavities.

1. The aorta. 11.
2. The pulmonary artery.

3, The musculi pectinati. 12.
4. The appendix of the right auricle. 13.
5. The anterior flap of the mitral valve.

6. The left coronary artery. 14,
7. A needle passed through the aortic opening. 16.
8. The apex of the heart. 16.
9. The left pulmonary veins. 17.

10. The right pulmonary veins.

Openings of the pulmonary veins in the wall of the
left auricle.

The septum.

A bristle passed through the left auriculo-ventricular
opening.

The appendix of the left auricle.

The posterior flap of: the mitral valves.

The musculus papillaris.

The columne carnee.

N. B.—The specimen from which these four plates were taken was the heart of an adult male, perfectly healthy and
normal, excepting the little ima thyroidea artery, which arises trom the innominate, as seen in Figures 1 and 2.
late 43

 

 

eta? Photographed and Colored from Nature by Georce Mc, CLeLLan, MD,

Copyrnght/89/.by GeorseMc Cue an MD.

Fig 4

Von I

 

Armsirong 6 Co Lith. Boston.

 
THE REGION OF THE THORAX. 303

brought into relation with the air-cells of the pulmonary lobules by
endosmosis.

The foetal heart, and the circulation of the blood before
birth.—In the early stages of the foetal formation the heart occupies
nearly the whole of the thoracic cavity, and, comparatively speaking, is
much larger than it is subsequent to birth. The auricular portion exceeds
the ventricular, and the right auricle is more capacious than the left, the
right ventricle being also smaller than its fellow. The organ is placed
vertically within the thorax in its early stages. Just before birth, how-
ever, these peculiarities disappear, and the ventricular portion becomes the
larger, the left having the thicker walls, and the whole organ rapidly
approaches its normal condition for life. The internal structure of the
fetal heart is different from that of the adult chiefly in having an oval
opening (foramen ovale) between the auricles, which allows a commu-
nication from side to side, and in the large size of the Hustachian valve
(page 278), which directs the blood from the inferior vena cava through
the foramen ovale. The latter generally becomes closed within the first
week or ten days after birth, but may remain open longer, and in some
instances has been found to be slightly pervious at a greatage. The
Eustachian valve speedily dwindles after the establishment of the func-
tion of the lungs and the proper circulation of the blood. Contemporary
with these structural alterations changes occur in the great vessels which
are requisite for the independent circulation of the blood. The pulmo-
nary artery of the foetus, after leaving the right ventricle, gives off the
right pulmonary branch, and then divides into two other branches, the
first of which is as large as the pulmonary artery itself, about twelve milli-
metres, or half an inch, in length, and directly joins the aorta at the termi-
nation of its arch (page 290), while the other goes to the left lung. The
connecting branch between the pulmonary artery and the aorta is named the
ductus arteriosus. It is really the continuation of the pulmonary artery.

The fetal circulation (Plate 26, Fig. 2) consists of the entrance of
the arterial blood from the placenta into the body of the embryo at the
umbilicus, by means of the umbilical vein, which ascends to the under
surface of the liver.
304 THE REGION OF THE THORAX.

Within this organ the greater part of the blood first communicates
with the branches of the portal vein and with the hepatic veins, and thence
passes to the inferior vena cava, but a portion of the blood conveyed by
the umbilical vein is conducted by a small vessel directly to the upper
part of the inferior vena cava, without passing through the substance
of the liver: this vessel is called the ductus venosus (Plate 26, Fig. 2,
No. 5). The inferior vena cava empties all its blood into the right auricle,
whence it is directed by the Eustachian valve through the foramen ovale
into the left auricle. From the left auricle it passes through the left
auriculo-ventricular opening into the left ventricle, and thence by means
of the aorta it is distributed chiefly to the head, neck, and upper ex-
tremities. The more immediate supply of pure blood to these parts
accounts for their greater proportionate development at birth. The im-
pure blood from the upper part of the body is returned into the superior
vena cava, and by it to the right auricle, from which it passes through the
right auriculo-ventricular opening into the right ventricle. From the latter
it issues by the pulmonary artery, and is chiefly conveyed by its continua-
tion, the ductus arteriosus (Plate 26, Fig. 2, No. 13), into the upper portion
of the descending aorta, where it mixes probably with some of the blood
from the left ventricle passing through the arch of the aorta. From the
descending aorta the blood passes through the abdominal aorta into the
iliac arteries. The external iliac arteries carry part of this blood to the
lower extremities, but most of that in the internal iliac arteries is curiously
returned to the placenta by means of the hypogastric arteries, which are
the continuations of the superior vesical branches of the internal iliac
arteries (Plate 26, Fig. 2, Nos. 22 and 24). They pass out at the um-
bilicus, where, under the name of the wmbilical arteries, they twine round
the umbilical vein in the substance of the cord, and return their impure
blood to the placenta to be re-oxygenated. The umbilical vein and the
ductus venosus become empty at birth, contract, and are ultimately con-
verted into fibrous cords which occupy the fissure of the ductus venosus
of the liver and become its round ligament. They are usually obliterated
about the fifth day after birth. The ductus arteriosus and the hypogastric
arteries also contract after birth, and become closed, the former usually
THE REGION OF THE THORAX. 305

within the first ten days, and the latter within the first three or four days.
The remains of the ductus arteriosus constitute the ligamentum arteriosum,
which is attached to the concavity of the aorta at the left end of the arch.
The bands resulting from the obliteration of the hypogastric arteries form
the lateral false ligaments of the bladder.

The lungs previous to birth are quite solid, and are packed into the
back parts of the recesses on each side of the thorax. They receive only
a slight amount of blood by their proper branches of the pulmonary artery,
and return it to the left auricle by the pulmonary veins.

The changes in the heart and vascular system, upon which depends the
differentiation of the circulation of the blood before and after birth, are
all gradual and commensurate with the processes of development. They
are almost completed by the establishment of the function of the lungs
when respiration occurs and the connection with the placenta is severed.
At birth, the first inspiratory effort appears to be due to the stimulus of
the atmosphere upon the surface nerves, which is immediately imparted
to the pneumogastric and phrenic nerves, in consequence of which the
phenomena of respiration ensue. The first expansion of the lungs is
attended with the passage of blood through the pulmonary veins into
the left auricle, which exerts a considerable degree of pressure upon the
septal valve, so as to bring it in contact with the margin of the foramen
ovale, and thus the blood is directed through the left auriculo-ventricular
opening into the left ventricle. Coincident with this is the diminution
of the tension between the auricles, owing to the arrest of the incoming
blood from the umbilical vein, so that there is little obstacle to the blood
from the inferior vena cava joining that from the superior vena cava in
its passage through the right auriculo-ventricular opening into the right
ventricle. The expansion of the lungs in inspiration induces the suction
of the blood from the right ventricle into the pulmonary artery and from
the left ventricle into the aorta. The passage of the blood through the
ductus arteriosus ceases with the determination of the pulmonary circula-
tion and the mechanical influence exerted upon the vessels at the root of
the heart through their connections with the deep cervical fascia.

The circulation of the blood after birth, when the organs have
39
306 THE REGION OF THE THORAX.

attained their full development, consists in the reception of all the
venous blood returned from the body through the vene cave into the
right auricle and its passage into the right ventricle, whence it is pro-
pelled through the right and left branches of the pulmonary artery into
the lungs. Here the blood is subjected to the purifying influence of the air
within the lobules (page 269), and then returned by the pulmonary veins
to the left auricle. This constitutes the pulmonary circulation. The pro-
pulsion of the arterial blood from the left ventricle by means of the aorta |
to be distributed throughout the body, and its return by the capillaries into
the veins which conduct it to the right auricle, constitute the systemic
circulation. The latter, in reality, consists of numerous small circulations
everywhere, each of which is made up of supplying arteries, intervening
capillaries, and draining veins. In its passage to and from the heart the
blood is propelled in a rhythmic current in consequence of the peculiar
elastic and muscular contraction of the walls of the ventricles. As it is
forced through the openings between the cavities or at the orifices of the
vessels leading out of them, every impulse is followed by the closure of the
various valves which normally prevent the regurgitation of the blood, and
thus characteristic sounds are produced.

The heart-sounds in health consist of a long sound (ud), succeeded
by a short one (dip), which is immediately followed by a pause equal in
duration to the second sound; and then the long and short sounds are
repeated, and so on. The first sownd is caused chiefly by the closing of
the auriculo-ventricular valves, with the accompanying rush of the blood
from the ventricles in consequence of their systole or contraction. This
is synchronous with the beat of the apex against the chest wall. The
second sound is produced by the abrupt closure of the semilunar valves
which follows upon the emptying of the ventricles at the close of their
contraction, and by the pressure of the blood upon them, which, after it
has been driven into the pulmonary artery and the aorta, is forced into
the sinuses of Valsalva in its endeavor to return. The degree of the
pressure upon the semilunar valves, which is proportionate to the volume
of the blood in the great vessels, causes the distinctness with which the
second sound is heard, and accounts for what is called its accentuation.
THE REGION OF THE THORAX. 307

Both the right and left ventricles contract and dilate in unison, as both
the right and left auricles also do.

The arterial pulse is produced by, and coincident with, the ventricular
contraction, as may be ascertained upon auscultation and feeling the pulse
in any one of the superficial arteries at the same time. In consequence
of this the second sound, which is produced by the simultaneous Closing
of the pulmonary and aortic semilunar valves, may be usually heard
with the stethoscope placed over the carotid arteries at the root of the
neck, as it is propagated in the blood-current from their origins. If a
murmur is detected during the ventricular systole it is probably due to
regurgitation of the blood from the pulmonary artery or the aorta, or to
some obstruction at one of the auriculo-ventricular openings. If in con-
nection with this there is absence of the second sound over the carotids,
aortic regurgitation may be inferred. The prolongation of the first or
second sounds, called their reduplication, is due to the want of harmonious
closure of the flaps of the respective valves producing them. When both
the auricle and the ventricle upon one side become dilated from any cause,
great tension is exerted upon the fibrous ring to which the base of the
auriculo-ventricular valve is attached, and it is rendered “incompetent.”
The tricuspid valve is peculiarly constructed so that regurgitation may
take place through it whenever the right ventricle is in any way embar-
rassed, and the third flap of this valve has on this account been compared
to a “safety arrangement,” as it provides this means of relief from the
strain that would otherwise be exerted upon the pulmonary capillaries.
Disease of the tricuspid valve is rare, probably on account of this
anatomical provision, but when it allows of regurgitation of the venous
blood back into the right auricle it is often associated with a pulse in the
jugular veins. This is more especially noticeable in the right jugular
vein, as the reflux blood passes more readily into the right innominate
vein. What is called the respiratory pulse is often observable in the
superficial cervical veins, even in health, after rapid exercise, as in
dancing, when, during the rapid efforts at expiration and inspiration, and
before harmonious respiration is regained, the blood is prevented from
emptying itself evenly from the veins into the superior vena cava. As
308 THE REGION OF THE THORAX.

the left side of the heart is always engaged in forcing the arterial blood
throughout the system, it naturally follows that the mitral valve is liable
to suffer in consequence of over-work. JMMitral regurgitation is therefore
the most frequent of valvular affections, and the murmur which charac-
terizes it necessarily occurs with the ventricular systole. This murmur
can be distinguished from aortic regurgitation by not being noticeable in
the carotid arteries, but by being more clearly heard over the apex and
’ below the left shoulder-blade, where the left ventricle is nearest the tho-
racic wall without the intervention of any other portion of the heart.

In order to determine upon a topographical survey of the chest
(Plate 27) for the clinical study of the relative positions of the important
parts of the heart and lungs, it is well to bear in mind certain established
facts, and to pay especial attention to the landmarks of this region. There
is very little possibility of change in the normal position of the dase of
the heart in the adult, as has been explained (page 273), in consequence
of the manner in which the pericardium is attached to the central tendon
of the diaphragm below and to the deep cervical fascia above.

The apex of the heart, on the contrary, is continually changing its
position during life, as it is free within the pericardium, and extends
upon the left muscular arch of the diaphragm, which overlies the stomach,
so that not only does it naturally accommodate itself to the diaphragmatic
movements of respiration, but its freedom is also somewhat interfered with
when the stomach is distended. In this connection it should be remem-
bered that the left lobe of the liver overlaps the stomach, even so far as
its cardiac extremity, and thus intervenes between the latter and the
diaphragm (Plate 29). Distention of the stomach with gas from fermen-
tation in digestion in various dyspeptic conditions is often attended with
cardiac disturbance, but this disturbance occurs chiefly through the tension
exerted upon the diaphragm and the consequent limitation of the ordinary
moving space of the heart within the pericardial sac. Undoubtedly, also,
many of the nervous symptoms attendant upon such a condition may be
ascribed to the dragging upon the filaments of the pneumogastric nerves
which accompany the cesophagus through its proper opening in the dia-
phragm to their distribution over the stomach (Plate 36). The degree
oO

THE REGION OF THE THORAX. 309

of displacement of the heart in consequence of distention of the stomach
is, however, greatly exaggerated, for, except in very unusual cases, the
stomach when distended must enlarge toward its free border at the ex-
pense of the abdominal cavity rather than of the thoracic. The anatomy
of the diaphragm is described on page 320, but its ever-changing posi-
tion at the sides renders the study of its relations to the adjacent viscera
of the thorax and abdomen of peculiar value and interest. After death
the diaphragm is usually found arching upward to the fullest extent,
owing to the collapsed state of the lungs from expiration; but during
life its lateral contractions produce changes which are more apparent
than real, for there are alterations in the relative positions of the ribs
and sternum above and below, which are coincident and exert a modi-
fying influence on whatever effect it may have upon the neighboring
viscera. It should be remembered that the ribs are raised in inspiration
and lowered in expiration, and that their relations are thus materially
altered. To be of assistance in arriving at any degree of accuracy in
observation, these alterations are further to be considered from the stand-
point of the individual peculiarities of conformation of the chest; and
only by those who are most cognizant of what may be termed the normal
changes are the difficulties in the way of mapping out the position of the
viscera upon the living body properly appreciated.

The shape of the thorax varies considerably in different individuals.
The ribs vary in breadth, as do also the sternum and the intervening
cartilages (Plates 27, 28, 29).

The uncertainty attending the many descriptions of the position of the
heart within the thorax is mainly due to a want of proper consideration
of the relative bearing of this important organ to the general conformation
and development of the bony cage which contains it. It should be under-
stood and remembered at the outset of every physical examination that the
precise location of the various parts must be settled with exactness upon
each individual, and that any standard of measurement can be applied
only with latitude. It is easy enough to point out where things ought
to be beneath the skin, but to say that they actually are at any one
spot, without auscultation and percussion, is not compatible with extensive
310 THE REGION OF THE THORAX.

observation upon the living or the dead. An allowance should always
be made in fixing upon any diagnostic point, but it may be considerably —
diminished if sufficient attention is paid to the peculiarities of individual
conformation.

It has been asserted (page 245) that the ridge between the manubrium
and gladiolus of the sternum is the most reliable landmark in the front
of the chest. It indicates the position of the sternal attachment of the
cartilage of the second rib, and therefore by counting downward on either
side the numerical order of the several true ribs may be ascertained. As
already stated, the base of the heart may be considered to be anatomically
fixed at the junction of the third costal cartilage with the right border of
the sternum. This is fortunate for diagnostic purposes, because it assists
in determining the localization of the valves of the heart. The apex of
the heart in a well-formed adult may be felt beating at each contraction
between the cartilages of the fifth and sixth ribs, to the left of the sternum,
and about nine centimetres, or three and a half inches, from its middle.

The thorax should give a clear note on percussion, except over the
position of the heart, where dulness is elicited. Only a small triangular
part of the heart is uncovered by the lungs and pleure during full inspi-
ration (Plates 27, 29, and 30), in consequence of the deflection of the left
lung from the middle line. This is known as the area of the greatest
cardiac dulness. The limitations of this area may be approximately indi-
cated by drawing a line from the middle of the sternum opposite the fourth
left costal cartilage to the point of junction of the left fifth rib and its
cartilage, and from this point horizontally back to the mid-sternal line
(Plate 27).

The following survey of the anterior view of the chest is based upon
many careful observations upon the living, and it is believed to be verified
by the dissections of this region, as represented in Plates 29, 30, 31, 32,
33, 34, and 35. The references throughout the text, as to the position
and bearing of the lungs, the heart, and the great vessels, are also the
result of personal study.

In the adult, standing erect, with the shoulders squared and the arms
at the sides, if the breath is held upon expiration, the position of the
THE REGION OF THE THORAX. 311

valves of the heart may be ascertained, after determining upon the rela-
tions of the base and apex of the heart as above described (Plate 27).
The right auriculo-ventricular or tricuspid valve is situated behind the
middle of the sternum, opposite the interspace between the right fourth
and fifth ribs. The left auriculo-ventricular or mitral valve is situated
just above the cartilage of the left fourth rib, about two and a half centi-
metres, or an inch, from ‘the border of the sternum. The aortic semi-
lunar valves are behind the sternum, between the junction of the cartilage
of the left fourth rib and the mid-sternal line. The semiluwnar valves of
the pulmonary artery are just behind the junction of the cartilage of the
left third rib with the border of the sternum. If the breath is held upon
inspiration, the interposition of the lungs renders the heart-sounds obscure
and uncertain. Fortunately, the structure of the sternum is such that in
a measure it serves asea sounding-board, and does not interfere with the
transmission of the sounds through a stethoscope.

The difficulty of fixing definitely the points where the sounds of the
cardiac valves can be detected by the ear applied to the chest is greatly
increased in examining young cliildren, in whom the position of the heart
is relatively higher and consequently the sounds of its valves are confused
with those of the respiratory organs. In infancy and throughout child-
hood the heart also is proportionately of greater breadth’in comparison
with the chest (Plate 42), and the apex-beat will therefore generally be
found at a point higher and more external than it is in the adult. The
so-called nipple-line is not to be relied upon for accurate reference, as the
position of the nipple, although usually occupying the fourth intercostal
space upon both sides, is subject to variation, as stated in the description
of the breast (page 250).

With regard to the physical examination of the chest for the recog-
nition of the condition of the lungs there are several points regarding
which the anatomy of the region will offer elucidation. When the hands
are held in each other at the back, with the body in. the upright position,
percussion over the anterior wall of the chest will reveal a clear note
wherever the lung-tissue is healthy. By this means an experienced ear
and a light touch may enable the physician to map out the area of the
312 THE REGION OF THE THORAX.

lungs in inspiration (Plate 27) and thus ascertain the degree of their
expansion. Over the apices of the lungs at the root of the neck there
is a slight resonance, but it is much more clear below the clavicles, where
the amount of lung, tissue is greater. Generally in this locality there is
upon the right side normally a comparative degree of dulness, owing to
the interposition of the innominate artery and innominate vein. Both
sides of the chest should always be percussed symmetrically downward,
the area of the heart’s dulness being allowed for upon the left side. By
this means it will be found that in the middle over the sternum during
inspiration the resonance is clearest along the upper part of the gladiolus,
above the attachment of the cartilages of the fourth ribs. Upon the
right side the resonance diminishes below the level of the jifth rib, as the
lung thins out over the liver, until the upper border of the seventh rib
is reached, where the absolute dulness of the liver commences. Upon
the left side below the sixth rib percussion will gradually elicit the tym-
panitic note of the stomach.

The posterior lower level lines of the lungs are indicated in the topo-
graphical survey of the back, which will be found in Vol. IT.

The space included between the reflections of the two pleure posteriorly,
extending from the roots of the lungs and the pericardium to the sides
of the bodies of the dorsal vertebre, is called the posterior mediastinum
(page 263). It contains the descending thoracic aorta and its intercostal
branches, the cesophagus, the pneumogastric nerves, the thoracic duct,.
the ven azygos major and minor, the splanchnic nerves, and some lym-
phatic glands (Plates 36, 37, 38, and 41, Fig. 2).

The descending thoracic aorta commences at the termination of the
arch, about the lower border of the body of the fourth dorsal vertebra
on the left side, and extends to the twelfth dorsal vertebra. It is closely
connected to the spine by a strong investment of the endothoracic fascia,
and ifs course is not straight, as it follows the natural curvature of the
spine in this region, and gradually approaches the middle line, where it
passes through its proper opening in the diaphragm to become the abdom-
inal aorta. The thoracic aorta is separated from the pericardium by the
esophagus and the pneumogastric nerves (Plates 37 and 38). The root
THE REGION OF THE THORAX. 3138

of the left lung is in front of its upper portion (Plates 89 and 40), which
also indents the lung in this relation. As it descends, this portion of the
aorta diminishes slightly in calibre (from twenty-three to twenty-one
millimetres, or from eleven-twelfths to five-sixths of an inch, in diameter)
and gives off at intervals numerous branches. From the anterior surface
arise the upper and lower right and left bronchial arteries, which accom-
pany the respective bronchi into the lungs, several pericardiac arteries,
and four or five esophageal arteries, which are distributed to the walls
of the pericardium and csophagus and also to the posterior mediastinal
lymphatic glands. From the posterior surface upon each side there are
usually nine intercostal arteries given off. There are eleven pairs of
intercostal arteries, but the upper two are derived from the superior inter-
costal branch of the subclavian artery (page 229). The right aortic
intercostal arteries are longer than the left, owing to the position of the
aorta, being for the most part on the left side of the spine, and the
upper ones upon each side ascend obliquely to pass along the intercostal
spaces, while the lower ones pass transversely.

Upon reaching the intercostal spaces, between the side of the vertebra
and the superior costo-transverse ligament, each artery divides into an
anterior and a posterior branch. The anterior branch is the largest, and
at first runs along the middie of the intercostal space upon the external
intercostal muscle, and, in consequence of the internal intercostal muscle
being deficient here, is separated from the thoracic cavity only by the
endothoracic fascia and costal reflection of the pleura. At the angle of
the rib the vessel passes between the two layers of intercostal muscles
and becomes lodged in the sub-costal groove of the lower border of the rib
above, with its companion vein above and nerve below (Plate 37). Before
doing so it sends off a tiny branch called the collateral intercostal artery,
which runs along the upper border of the rib below. This branch is
sometimes large enough to cause troublesome bleeding, and in entering
a trocar through any one of the spaces it is better to select the middle
of the space, instead of just above the border of the lower rib as generally
recommended. The anterior branches of the intercostal arteries anasto-

mose with one another and with the branches from the internal mammary
40
1

2.

ew

Pe

8.

oaReNne

PLATE 44.

Figure 1.

Dissection of the anterior thoracic region, showing the superficial fascia and mammary gland on the left side, and
the great pectoral muscle on the right. The arms are drawn upward and outward to bring the axillary borders into
prominence and expose their relations to the vessels and lymphatic glands; of importance in operations upon the breast.
From a female aged twenty-four years.

 

. The converging fibres. of the right pectoralis major 9. The middle clavicular nerves.
muscle, passing to their insertion on the humerus. 10, The internal clavicular nerve.

The anterior cutaneous branch of the first intercostal | 11. The fascia over the great pectoral muscle.
nerve, and the first perforating branch of the in- | 12. The sternal nerves.
ternal mammary artery. 18, The superficial axillary veins.

. The sub-scapular artery, veins, and nerves. 14. The axillary glands.

. The anterior cutaneous branch of the second inter- | 15. The superior division of the second, or principal,
costal nerve, and the second, or principal, perforating perforating branch of the internal mammary ar-
branch of the internal mammary artery. tery.

. The long thoracic nerve. 16. The inferior division of the second perforating branch

. The anterior cutaneous branch of the third intercostal of the internal mammary artery.
nerve, and the third perforating branch of the in- | 17. The superficial pectoral fascia, surrounding the mam-
ternal mammary artery. mary gland.

. The long thoracic artery, coursing along the axillary | 18. The left nipple, with its areola.
border of the pectoralis major muscle when in this | 19. The lower portion of the mammary gland, carefully
position. dissected to show the lactiferous lobes and ducts.

The anterior cutaneous branch of the fourth intercostal | 20. The superficial cutaneous veins.
nerve, and the fourth perforating branch of the in- .
ternal mammary artery.

Figure 2.

Dissection of the muscles of the shoulder and axilla on the right side. The lymphatic glands and vessels are super
posed upon the photograph, from notes of many observations, to show their proper relations.

. The temporal muscle.
. The deltoid muscle, reflected.

The pectoralis major muscle, TEHGutE:

. The triceps muscle.
. The biceps muscle.
. The lymphatic chain along the inner border of the

eoracoid head of the biceps muscle.

. The coraco-brachialis muscle.

. The sub-scapularis muscle.

. The latissimus dorsi muscle.

. The lymphatic chain along the axillary border of the

latissimus dorsi muscle.
The compressor naris muscle.

. The buccinator muscle.
. The masseter muscle.

The depressor anguli oris muscle.
The anterior portion of the digastric muscle,

 

16.
17,
18.

19.
20.
21,
22.
23.
24,

25.
26.
27,

28,

The mylo-hyoid muscle.

The thyro-hyoid muscle.

The head of the humerus, covered with the capsular
ligament.

The sterno-mastoid muscle.

The glenoid head of the biceps muscle.

The sterno-thyroid muscle.

The sterno-hyoid muscle.

The coracoid head of the biceps muscle.

The coracoid attachment of the pectoralis minor mus-
ele.

The axillary glands in the apex of the axilla.

The pectoralis minor muscle.

The lymphatic chain along the axillary border of the
pectoralis minor muscle.

The serratus magnus muscle.
ected

Pho

7

ig

Ta,

Di

he

and Ce

 

Georce Mc. CLeLtan, MD.

Copynent/89/by GeorseMe Ce. an, M.D.

 

 

VOL 1

Armstrong & Co. Lith Boston
THE REGION OF THE THORAX. 315

artery in front (page 257). They distribute blood to the contiguous ribs
and muscles, and also by perforating branches to the pectoral muscles,
mammary gland, and serratus magnus muscle. The anterior intercostal
vessels and nerves pass, as they enter between the intercostal muscles,
beneath the chain of sympathetic nerve ganglia (Plates 36 and 37).
The posterior intercostal arteries pass backward with the dorsal nerves
between the transverse processes of the contiguous vertebre, and divide
opposite the intervertebral foramina into the spinal and dorsal branches.
The spinal arterves enter the spinal canal and immediately subdivide and
establish communications with the vessels above and below, so that there
are arterial plexuses formed in front and at the back of the cord, called
the anterior. and posterior neural rete mirabile. A branch of each spinal
artery also pierces the dura mater of the spinal cord, and with similar
branches anastomoses upon the anterior and posterior surfaces of the cord
itself. The dorsal arteries divide into internal and external muscular
branches, which supply the various layers of dorsal muscles.

The cesophagus is the continuation of the pharynx, and begins in
the neck on a level with the sixth cervical vertebra and the lower border
of the cricoid cartilage (Plate 12). It is the narrowest portion of the
digestive canal, and leads directly into the stomach, passing in front of
the spine to the transverse portion of the arch of the aorta, thence
through the posterior mediastinum in front of the descending thoracic
aorta (Plate 37) to its proper opening in the diaphragm opposite the
ninth dorsal vertebra. It is about twenty-five centimetres, or nine’ or
ten inches, in length. It is most constricted in relation to the fourth
dorsal vertebra and at the diaphragm. Its course is somewhat peculiar,
being not exactly straight, and, besides conforming to the curvatures of
the spine in the different regions through which it passes, it deviates
from the middle line in certain localities. At the root of the neck
it bulges to the left of the trachea (Plate 36), which, with the lobe of
the thyroid body and the left recurrent laryngeal nerve, is situated in
front of it. It is separated from the longus colli muscles by the pre-
vertebral expansion of the deep cervical fascia. The left inferior thyroid
and common carotid arteries, and the thoracic duct, are close to the left
316 THE REGION OF THE THORAX.

side of it. Within the thorax the cesophagus passes through the superior
mediastinum, extending over a little to the right of the middle line, lying
in front of the bodies of the upper dorsal vertebree. In the posterior
mediastinum it is separated from the vertebre by the thoracic duct, the
vena azygos major, and the right upper intercostal arteries. Here it passes
forward and to the /eft, and is surrounded below the roots of the lungs by
the esophageal plexus of nerves, which are derived from the right pneumo-
gastric nerve posteriorly and from the left pneumogastric nerve anteriorly.
It is in relation with both pleura, but more especially the right, and has
in front of it the trachea, the left bronchus, the arch of the aorta, and the
posterior surface of the pericardium in relation to the left auricle (Plates
38 and 39). The cesophagus terminates at the cardiac orifice of the
stomach, about two centimetres, or three-fourths of an inch, to the left
of the middle line, passing through the diaphragm, and entering the
cavity of the abdomen behind the left lateral ligament of the liver and
the adjoining peritoneal layers of the lesser omentum.

Upon section the cesophagus appears like a cord with a stellate lumen
(Plate 41, Fig. 2, No. 12). It will be observed from the above that the
direction of the cesophagus presents two lateral curves, one at the root
of the neck and the other at the diaphragm, which should not be over-
looked in the introduction of a probang or of the stomach-pump. The
diameter of the canal varies, being normally at the above-mentioned points
of constriction thirteen millimetres, or about half an inch, and in the
rest of the passage from seventeen to twenty-one millimetres, or a little
over three-quarters of an inch. These measurements are considerably
increased by forcible distention: the narrowest portions, however, rarely
exceed twenty-two millimetres, or seven-eighths of an inch, in diameter,
while the rest of the gullet will stretch to thirty-six millimetres, or one
and a half inches. It follows, therefore, that foreign bodies when swal-
lowed are most apt to be arrested at either the upper or the lower portion
of the cesophagus.

The operation of esophagotomy for the removal of an impacted foreign
body is performed with the patient’s neck turned upon the right side
over a pillow, so as to render the /eft side prominent where the csoph-
THE REGION OF THE THORAX. 317

agus extends to the left of the middle line. The foreign body can
usually be felt, and thus serves as a guide. The incision should be free
and made parallel to the anterior border of the sterno-mastoid muscle,
and the carotid sheath carefully exposed. The latter, together with the
trachea, should be drawn forward and the sterno-mastoid muscle outward,
every precaution being exercised not to injure the thyroid body, the
thyroid vessels, or the recurrent laryngeal nerve, and especially to avoid
tearing the surrounding loose cellular tissue, which is very prone to diffuse
inflammation.

The distensibility of the cesophagus is due not only to the laxity of
its attachments, but also to the character of its coats. These consist of
an external or muscular coat, composed of outer longitudinal and inner
circular fibres, which are mostly well developed and pronounced in the
upper portion; a middle or areolar coat, consisting of elastic tissue in
which are embedded masses of adenoid tissue and rows of little racemose
cesophageal glands (larger below than above), and an internal or mucous
coat, which is continuous with the mucous lining of the pharynx above
and with the stomach below, and which when the cesophagus is empty
is folded into vertical ruge. The mucous membrane is quite thick, and
is lined with scaly epithelium. The arteries to the cesophagus are derived
from various sources. In the neck it receives branches from the inferior
thyroid artery, within the thorax branches from the descending thoracic
aorta, and below the diaphragm a few twigs from the gastric artery. Its
veins empty their blood into the gastric, the vena azygos major, and the
inferior thyroid veins in their respective localities. The nerves are sup-
plied from the cesophageal plexus formed by the pneumogastrics and some
filaments from the first dorsal ganglion of the sympathetic nerve.

The pnewmogastric nerves within the thorax hold different relations
upon the two sides. The right pnewmogastric enters from the neck, be-
tween the subclavian artery and subclavian vein, and descends by the side
of the trachea to the root of the lung (Plate 39). After giving off the
recurrent branches and others which communicate with similar branches
from the left pneumogastric nerve and form the posterior pulmonary and
cesophageal plexuses, it continues as a single cord along the posterior
318 THE REGION OF THE THORAX.

wall of the cesophagus to the stomach. The left pneumogastric nerve,
after entering the thorax from the neck between the left subclavian and
carotid arteries and behind the left innominate vein, passes over the arch
of the aorta and behind the root of the left lung to the anterior surface
of the cesophagus. In its course it gives off branches which combine
with those from the right pneumogastric nerve, as already stated, in the
formation of the pulmonary and cesophageal plexuses, and continues as a
single cord along the anterior wall of the cesophagus to the stomach.
The recurrent laryngeal nerves are given off from the pneumogastric
nerves within the limits of the superior mediastinum, and have already
been particularly described (page 185).

The thoracic duct is the upward continuation of the receptaculum
chyli, which receives the converging lacteal vessels from the intestines
and the lymphatic vessels from the lower portion of the body, which are
described with the region of the abdomen in Vol. II. The duct enters
the posterior mediastinum by the aortic opening in the diaphragm, to the
right side of the aorta (Plate 37, No. 8, and Plate 38, No. 2), and ascends
in a sinuous course in close relation to the right pleural boundary of this
space as far as the body of the third dorsal vertebra. Here it passes
across to the left side behind the arch of the aorta and the cesophagus,
and curves upward to the left side of the latter, between it and the left
pleura, to enter the superior mediastinum. Very often the thoracic duct
in its upper portion divides into branches, and it usually presents a dila-
tation where it crosses over the spine. It receives the pleural, intercostal,
and left pulmonic lymphatic vessels. When dilated it appears irregular
and nodulous, owing to the many pairs of valves with which it is pro-
vided. The valves are most numerous in the upper portion, where it
ascends between the cesophagus and the left subclavian artery into the
neck as high as the seventh cervical vertebra. It then curves down-
ward over the subclavian artery, near the anterior border of the scalenus
anticus muscle, and empties into the back part of the confluence of the
left common jugular and subclavian veins (Plate 20, No. 69). At the
orifice of the duct there are two well-marked valves, which guard against
any regurgitation of the blood from the veins into its canal.
THE REGION OF THE THORAX. 319

The vena azygos major is the great connecting link between the
superior and inferior vene cave, making up for their deficiency in the
situation of the heart. It commences by tributaries from the right lumbar
and renal veins, and often from the inferior vena cava itself, and, passing
through the diaphragm at the aortic opening, ascends upon the right side
of the spine over the right intercostal arteries to the third dorsal vertebra,
whence it arches forward to empty into the superior vena cava as it
becomes covered by the pericardium (Plate 37, No. 30). It receives the
lower nine or ten right intercostal veins, the_ spinal veins, and the pos-
terior mediastinal, cesophageal, and right ‘bronchial veins. About the
sixth dorsal vertebra the vena azygos major is usually joined by the
vena azygos minor (Plate 38, No. 13), which ascends up the left side of
the spine (Plate 36, No. 84). The latter vein commences in the abdo-
men by tributaries from the left lumbar veins and the left renal vein,
and ascends to the left of the aorta through the left crus of the dia-
phragm. It receives the lower six or seven of the intercostal veins,
besides some of the mediastinal and cesophageal veins. The left upper
intercostal veins terminate in a trunk called the superior vena azygos
minor, which empties into the vena azygos major generally, but some-
times into the inferior vena azygos minor. All the azygos veins are
provided with valves, which are not very perfect, however.

The splanchnic nerves are the sympathetic nerve cords which are
made up of branches from the lower thoracic ganglia, and are distributed
to the abdominal plexuses under the names of the greater and lesser
splanchnic nerves (Plate 36, Nos. 80 and 83, and Plate 37, Nos. 13 and
15). The sympathetic ganglia in the thoracic region vary in number
upon each side from ten to twelve, in consequence of several of them
being often united. The first is the largest, and they are mostly situated
over the heads of the ribs. They are small, grayish-pink, irregular bodies
connected by broad, thin, grayish branches, and each ganglion is also con-
nected by a couple of branches, one white and one gray, with the neigh-
boring intercostal nerve. It is thought that these connecting links with
the spinal nerves consist of fibres which leave the ganglia at their inner
branches and endow them with vaso-motor and viscero-inhibitory functions.
. 820 THE DIAPHRAGM.

The nerves from the four upper ganglia are quite small, and pass inward
to join the cardiac and posterior pulmonary plexuses. The nerves from
the siz lower ganglia constitute the greater, the lesser, and the smaller
splanchnic nerves. The great splanchnic nerve is composed of the most
numerous filaments from the fifth, sixth, seventh, eighth, ninth, and tenth
ganglia, which combine into a single trunk, and, passing through the
crus of the diaphragm on the corresponding side, join the solar, renal,
and supra-renal plexuses. The lesser splanchnic nerve arises by branches
from the tenth and eleventh ganglia, and passes generally to the cceliac
plexus; and the smallest splanchnic nerve arises as a collateral branch
from the twelfth ganglion, and terminates in the renal plexus. The
chains of the sympathetic ganglia and their nerve-cords are covered by
the reflection of the costal pleura upon each side, which holds them in
place, and which must. be removed before they can be examined and
followed through the diaphragm. The association of the filaments of the
splanchnic nerves with the solar plexus probably accounts for many of
the obscure symptoms complained of in dyspepsia, which by reflex
action manifest themselves in pain in the area of distribution of the
cutaneous nerves of the upper part of the back.

THE DIAPHRAGM.

The diaphragm is the thin, movable, arching partition which separates
the cavity of the thorax from the cavity of the abdomen. Its construction
is very peculiar, as it consists of muscular and tendinous portions which
arise by numerous digitations and, arching upward and inward, converge
to be inserted into a common central tendon. To the upper surface of the
central tendon are attached the fibrous pericardium and the dense lateral
bands which are prolonged from the deep cervical fascia, already described
(page 259). These serve to maintain the arch of the diaphragm and to
keep the central tendon in position while the muscular portions are in
constant motion during respiration (page 273). When looked at from
below, the whole diaphragm resembles somewhat a large palm-leaf, while
the central tendon appears almost a counterpart in form: hence the differ-
THE DIAPHRAGM. ‘ 321

ent portions of each, in front and at the sides, are called the leaflets. Of
these the right leaflet is the largest. In structure the central tendon con-
sists of intersecting fibres which pass in all directions and then radiate
among the muscular fasciculi, thus affording additional strength. It is of
a glistening bluish-white color. The muscular portion of the diaphragm
arises by fleshy digitations from the ensiform cartilage, from the inner
surfaces of the six lower ribs on each side, interdigitating with the attach-
ment of the transversales abdominis muscles, and from the tendinous arches
over the quadratus lumborum and psoas muscles on each side, which con-
sist of condensations of the extra-peritoneal fascia in this locality, and are
known, from their ligamentous nature, respectively as the ligamentum arcu-
atum externum and the ligamentum arcuatum internum (Plate 63, Nos. 6
and 31, Vol. II.). The ligamentum arcuatum externum extends from the
twelfth rib to the transverse process of the first lumbar vertebra, and the
ligamentum arcuatum internum extends from the transverse process of the
first lumbar vertebra to the body of the second. Lower down upon the
lumbar vertebree are two variably-developed and always unsymmetrical
fleshy portions, called the crura of the diaphragm, because their com-
ponent fibres in passing upward cross each other in such a way that
they usually form a figure-of-eight arrangement around the openings for
the aorta and the esophagus (Plates 62 and 63, Vol. IL).

The aortic opening is in the middle line in front of the spine between
the two crura, and gives passage to the descending aorta, with the thoracie
duct and the vena azygos major on its right side. The esophageal opening
is in the muscular portion above and in front of the aortic opening, and
transmits, besides the cesophagus, the right and left pneumogastric nerves
(page 817). To the right of the latter, and in the highest part of the
central tendon, is the opening for the inferior vena cava, which also gives
passage upward to some of the hepatic lymphatic vessels, and occasionally
to a branch of the right phrenic nerve. The wall of the inferior vena cava
is adherent to the central tendon where it passes through it, so that it is
not subjected to pressure in the action of the adjacent muscular leaflet.
Besides these three great openings there are several smaller ones under the

crura, which allow the splanchnic nerves to enter the abdomen from the
' 41
322 THE DIAPHRAGM.

thorax (page 320). On the left side the vena azygos minor gains entrance
to the thorax (page 319). On each side of the ensiform cartilage there is
a triangular space which gives passage to the epigastric branch of the
internal mammary artery, and to the lymphatic vessels from the anterior
wall of the abdomen into the anterior mediastinum (page 259). Occasion-
ally this becomes distended by an abscess or by a diaphragmatic hernia.
The diaphragm receives branches from the lower intercostal and internal
mammary arteries, but is mainly supplied with bldod by the two phrenic
arteries, which arise from the aorta just as it issues through its proper
opening.

The nerves of the diaphragm are the phrenic (page 207) and some of
the branches of the lower five or six intercostal nerves, which are rein-
forced by sympathetic fibres from the neighboring supra-renal plexuses.
These fibres form the diaphragmatic plexuses, and on the right side there
is a little ganglion (diaphragmaticum), from which filaments pass to the
liver. The diaphragm, next to the heart, is the most extraordinary
muscular arrangement in the body. Its upper surface arches into the
thoracic cavity, on each side, at variable heights (Plate 40), reaching
during expiration about the level of the fifth rib on the right side and of
the sixth rib on the left (page 265), and during znspiration sinking about
an inch, and thus pushing downward the abdominal viscera to a slight
degree. It is through the alternate contraction and relaxation of its
muscular portions that it enters largely into the mechanism of respira-
tion, aiding, in this important process, the expulsion of the air from the
lungs, by acting in harmony with the rest of the thoracic walls and
thus accommodating the cavity of the thorax to the degree of expansion
of these elastic organs. It is concerned in coughing, sneezing, and
laughing, as is manifest by its rapid contractions during those acts. It
also assists the abdominal muscles in compressing the viscera in vomiting
and defecation, and in the efforts of parturition. The under surface of the
diaphragm is covered by the peritoneum, as described with the region of
the abdomen in Vol. II.
THE REGION OF THE SHOULDER. 323

THE UPPER EXTREMITY.

The region of the shoulder is formed by the clavicle, the scapula,
and the upper part of the humerus (Plate 28), together with the structures
surrounding them, by which the upper extremity is attached to the thorax.
The skin over this region is comparatively thin, and although there may
be a considerable amount of fat in the subcutaneous tissue in certain
localities, which softens and subdues the surface markings, yet the promi-
nences of the bony framework can always be detected by the sense of
touch. The clavicle, the acromion process, and the spine of the scapula
are readily felt through the skin. In order to determine with accuracy
these landmarks it is advisable to refer to the corresponding points of the
opposite shoulder, and to take advantage of the extreme mobility of the
parts, for by rotation, abduction, and adduction many factors otherwise
obscure will be explained. The clavicle and the scapula are the frame-
work of the shoulder proper, and with those of the opposite’ side form
the shoulder girdle. This girdle is incomplete posteriorly, owing to the
gap between the two scapule, which are connected with the thorax solely
by muscles, while in front the two clavicles are supported upon and con-
nected with the top of the sternum. The shoulder girdle is remarkable
for its lightness and great mobility.

The clavicle, or collar bone, is the long irregular bone which extends
from the sternum outward over the first rib to the summit of the shoulder,
which it forms with the acromion process of the scapula (Plate 28). In
the upright position the clavicle usually inclines a little upward at its outer
end, and in the recumbent position this is increased in consequence of the
weight of the limb being removed. It is subject to variable physical pro-
portions, much depending upon the amount of strain and effort required of
the muscles which are attached to it. In the female it is usually smoother
and more slender than in the male. The right clavicle is often shorter
than the left. The bone presents a peculiar sigmoid curvature, so that
the anterior border begins by curving forward at the sternal end, and at
324 THE REGION OF THE SHOULDER.

the middle gradually curves backward to the acromial end, where it juts
outward. The posterior border is exactly the reverse. The degree of
curvature of the inner portion of the clavicle is very variable, especially
in men, the freedom and much of the grace of movement of the upper
extremity depending upon it. The sternal end is a prominent, rough,
thick, triangular-shaped process covered with a dense fibrous tissue. It
is provided with an irregular facet, which at its lower part rests upon
the shallow facet on the upper border of the sternum, and with the inter-
position of a disk of fibro-cartilage establishes the important sterno-
clavicular joint. This joint is provided with two pouches of synovial
membrane, one above and the other below the interarticular cartilage,
enclosed within a capsular ligament, of which there are two strong bands
of fibres, one stretching in front of and the other behind the surfaces of the
contiguous bones. They are called respectively the anterior and posterior
sterno-clavicular ligaments. These bands are reinforced by the intercla-
vicular ligament, which is in reality a differentiation of the deep cervical
fascia extending between the ends of the two clavicles across the top of
the sternum, and the costo-clavicular or rhomboid ligament, which ascends
inward from the cartilage of the first rib to the costal tuberosity of the
clavicle. This is now regarded as a differentiation of the sheath of the
subclavius muscle. It is remarkably strong, and limits the elevation of
the clavicle. Although the sterno-clavicular joint is the only direct con-
nection between the upper extremity and the thorax, it is very rarely
dislocated. It has been demonstrated that the peculiar sloping arrange-
ment of the articular facets of this joint allows the sternum to advance
slightly upon the end of the clavicle in inspiration (Morris). The acro-
mial end is rough, broad, and flattened, and presents upon its under surface
an obliquely-directed oval facet for articulation with the acromial process
of the scapula, forming the clamculo-acromial joint. This joint is provided
with superior and inferior ligaments, the superior being much the stronger,
and a reflected synovial membrane. ‘There is sometimes a rudimentary
fibro-cartilage within. It is capable of very slight gliding motion, but,
slight as this motion is, it is essential to the perfect freedom and _ har-
monious movement of the upper extremity. This joint is liable to rheu-
THE REGION OF THE SHOULDER. 325

matic inflammation, and the resulting rigidity will cause weakness in
certain movements of the limb. Very often the outer end of the clavicle
appears to be tilted above the acromion process, instead of occupying the
same level. This is probably due to partial separation of the connecting
ligaments from some severe strain. It is not attended with any impair-
ment of function. The inner two-thirds of the shaft of the clavicle are
rounded, and its posterior concave surface arches over the subclavian vein
and artery and the cords of the brachial plexus of nerves (Plates 30
and 31).

The upper surface of the bone is smooth and subcutaneous, being
readily recognizable through the skin, which is always thin and loosely
attached over it. The anterior and posterior borders of the upper surface
are roughened to a variable extent toward each end. The anterior border
gives attachment to the pectoralis major muscle at its inner half, and to
the deltoid muscle at its outer. The posterior border receives the insertion
of the clavicular portion of the sterno-mastoid muscle (page 197) inwardly,
and of the trapezius muscle outwardly (Plate 16). The under surface
presents at the sternal end a small facet for the reception of the first rib,
which is in reality a portion of the sternal articular surface. Close to the
outer side of this is the rough costal tuberosity for the attachment of the
rhomboid ligament, beyond which along the middle of the shaft is the
subclavian impression for the subclavius muscle. The costo-coracoid mem-
brane (page 255) is attached to the ridge in front of this impression and
a reflection of the deep cervical fascia from the omo-hyoid muscle to a
ridge behind it. Sometimes there is a rough line in the middle of the
impression, in which case it affords insertion to a fibrous septum in the
subclavius muscle.

Upon the under surface of the shaft, where it spreads out to form the
acromion, there is at its posterior border an eminence called the conoid
tubercle, from which an oblique line extends to the outer end of the anterior
border. The conoid tubercle is directly over the coracoid process of the
scapula, to which it is connected by the conoid hgament. The oblique
line gives attachment to the trapezoid ligament, which arises from the
coracoid process, the two ligaments being practically portions of one, the
15,
16,

1,

SeMmNngaaron

ry

21,

PLATE 45.

Figure 1.

Dissection of the right axillary space and inner side of the arm to show the relation of the vessels and nerves.

 

. The anterior ulnar vein. 17. The axillary glands embedded in adipose tissue.
. The posterior ulnar vein and branches of the internal | 18, The long thoracic artery.
cutaneous nerve. 19. The serratus magnus muscle.

. The median basilic vein. 20. The posterior thoracic nerve, or external respiratory
. The basilic vein. nerve of Bell.

The lesser internal cutaneous nerve. 21. The median vein.
. The greater internal cutaneous nerve. 22, The median cephalic vein.
. The triceps muscle. 23. The cephalic vein. "
. The ulnar nerve. 24. The biceps muscle. ‘
. The brachial vein. 25, The median nerve.
. The superior profunda artery and veins. 26. The brachial artery.
. The intercosto-humeral nerve. 27. The coraco-brachialis muscle.
. The latissimus dorsi muscle. 28. The deltoid muscle.
. The dorsalis scapule artery. 29. The cephalic vein.
. The sub-scapular artery and veins. 30. The sternal portion of the pectoralis major muscle.

The second sub-scapular nerve. 31. The right clavicle.

The third sub-scapular nerve. 32, The severed trapezius muscle.

Figure 2.

Deep dissection of the right axilla and inner side of the arm. The deltoid and pectoralis major and minor muscles
are detached and reflected to show the intricate relations of the brachial plexus of nerves to the artery and veins.

The fascia of the forearm and branches of the internal
cutaneous nerves.

. The median basilic vein.

. The median nerve covering the brachial artery.
. The anastomotica magna artery.

. The lesser internal cutaneous nerve.

The greater internal cutaneous nerve.
The ulnar nerve.
The superior profunda artery.

. The inferior profunda artery.

. The triceps muscle.

. The ulnar nerve, passing beneath the basilic vein.

. The latissimus dorsi muscle.

. Connecting venous link between the basilic and brach-

ial veins.
The basilic vein before it empties into the axillary vein.

. The axillary glands.
. The intercosto-humeral nerve.

The sub-scapular artery and veins.

The sub-scapular nerves.

The blending of the veins of the forearm over the ten-
don of the biceps muscle.

. The cephalic vein.

The biceps muscle.

 

31.

82.
33.

. The basilic vein.
. The brachial artery.

The brachial vein.

. The median nerve.

. The coracoid attachment of the biceps muscle.

. The musculo-cutaneous nerve.

. The thoracico-humeral artery.

. The coraco-brachialis muscle.

. The coracoid attachment of the severed pectoralis

minor muscle.

The inner cord of the brachial plexus of nerves.

The axillary artery.

The main brachial vein before its entrance into the
axillary vein.

. The brachial plexus of nerves.

. The acromio-thoracic artery.

. The severed pectoralis major muscle, reflected.

. The serratus magnus muscle.

. The posterior thoracic nerve.

. The short thoracic artery.

. The great axillary vein.

. The right clavicle.

. The trapezius muscle. .
 

Copynaht!89/,by GeorGeMc CLewtanMD
Armstrong & Co Lath, Boston

Colored From Nature oy Georce Mc, CLELLAN, MOD.

  
THE REGION OF THE SHOULDER. 327

coraco-clavicular ligament. They severally serve to restrain the move-
ments of the shoulder. The curved formation of the clavicle renders it
sufficiently elastic to compensate for its otherwise weak construction, so
that it is capable of moderating the effects of ordinary concussions re-_
ceived through the shoulder. Its outer surfaces consist of compact tissue,
which is much thicker at the middle of the bone, and the interior consists
of large-meshed spaces of cancellous tissue containing reddish-colored
marrow usually at the sternal end.

The clavicle is peculiar not only in that it is the first bone of the
skeleton to ossify, but also in that ossification begins in its primary
fibrous substance before the deposition of cartilage. At birth the entire
shaft is bony, although the ends are cartilaginous. The sternal end is
the sole epiphysis to the clavicle, and it is joined to the shaft about the
twenty-fifth year. It is rarely separated from the shaft by accident,
owing to the close ligamentous attachments of the sterno-clavicular joint,
but the powerful pectoralis major muscle might produce displacement in
a young person. This bone is frequently the seat of green-stick fracture,
owing to the exceedingly thick and loose periosteum which surrounds it in
childhood, as well as to its more early ossification. Practures of the clavicle
occur frequently at all ages, in consequence of the manner of its construc-
tion and its exposed position, and they are generally occasioned by indirect
violence. The commonest form of fracture occurs at the outer end of the
middle third of the bone, the resistance against concussion being weakened
by the junction of the two curves of the bone at this point. The direc-
tion of the fracture is oblique, and whatever degree of displacement may
occur is chiefly through the agency of the weight of the upper extremity
upon the outer fragment, the inner fragment rarely changing its position.
The outer fragment may also be drawn inward and somewhat rotated, so
that it projects in advance of the inner, by the contraction of the muscles
attached to the upper portion of the humerus and the coracoid process
of the scapula. The great obstacle to the complete reduction of such
a fracture is the inability to maintain the scapula in position, owing to
the gliding movements which are caused by its suspension in a sling of
muscles at the side of the thorax. All the ingenuity which has been
328 THE REGION OF THE SHOULDER.

expended in devising apparatus to restrain the scapula has thus far failed,
and consequently has been unsuccessful in overcoming the shortening of
the bone in the process of repair. Union, however, usually occurs with
marvellous rapidity (in from twelve to fourteen days), even when no
dressing has been used, and with little impairment of function.

The scapula, or shoulder-blade, is a flattish, triangular bone, situated
at the back of the upper part of the thorax, and, in the properly articu-
lated skeleton, extending between the second and seventh ribs. It consists
mainly of a broad thin plate, the dody, with raised and roughened borders.
Its dorsal surface is smooth and slightly convex, and is divided near its
upper third by a prominent projection of bone, the spine, into two hollows,
called the superior and inferior spinous fosse. ‘The supra-spinous fossa
lodges the supra-spinatus muscle, the fibres of which arise from its inner
portion and from the dense fascia with which it is invested and converge to
a strong tendon, which glides over the outer part of the fossa and across the
capsular ligament of the shoulder-joint to be inserted into the superior facet
on the greater tuberosity of the humerus. The infra-spinous fossa presents
several faint ridges toward the vertebral border, from which and their inter-
spaces the fibres of the infra-spinatus muscle arise, and blend to form a
tendon which passes over the upper part of the axillary border, from which
it is sometimes separated by a bursa, and across the capsular ligament
of the shoulder-joint, to be inserted into the middle facet on the greater
tuberosity of the humerus. This muscle is also firmly bound down by an
enveloping fascia. The teres minor muscle arises from the upper two-thirds
of the axillary border by fibres which pass obliquely upward and form a
narrow elongated mass, which mostly terminates in a tendon to be inserted
into the inferior facet on the greater tuberosity of the humerus, and by a
few muscular fibres into the humerus immediately below. The tendon of
this muscle also passes across the capsular ligament of the shoulder-joint.
The teres minor muscle is separated from the contiguous muscles by fibrous
lamin, which also give origin to some of its component fibres. About the
centre of the attachment of the teres minor there is a groove in the axil-
lary border, which accommodates the dorsalis scapule vessels. The teres
major muscle arises by fibres attached to the lower part of the axillary
THE REGION OF THE SHOULDER. 329

border, being separated by an oblique line from the preceding muscle, and
by fibres extending over the inferior angle of the scapula. They forma
broad mass which ascends outwardly, and, deviating from the teres minor,
from which it is separated by the middle portion of the triceps muscle, is
inserted by a flat tendon, about five centimetres, or two inches, in length,
into the internal ridge of the bicipital groove of the humerus. The lower
border of this tendon blends with the lower border of the latissimus dorsi
muscle, forming the posterior boundary of the axillary space (page 338),
and is inserted conjointly with it. The upper portion, however, is inserted
independently, having a synovial bursa interposed between it and the
proper attachment of the latissimus dorsi, which is at the bottom of the
upper part of the bicipital groove. The latter muscle as it passes from its
origin in the back (Vol. II.) crosses over the inferior angle of the scapula,
to which it is usually attached by a fibrous expansion, so that it serves
to retain this portion of the scapula in place. Occasionally there is no
connection between the latissimus dorsi muscles and the two scapule, they
being separated by synovial bursee. In such a condition the scapule are
apt to jut out like wings beneath the skin of the back.

The vertebral border between the inferior angle and the root of the
spine receives the attachment of the rhomboideus muscle. This muscle is
sometimes divided by a septum into two portions. The upper portion is
then called the rhomboideus minor, in distinction from the lower portion,
or rhomboideus major. ‘The fibres of the latter are inserted chiefly into
a tendinous arch extending from the inferior angle half-way up the verte-
bral border. The rhomboideus muscle consists of a flat mass of strongly-
developed fibres which arise from the spinous processes of the vertebra
prominens and the five upper dorsal vertebrae. Its action is to antago-
nize the serratus magnus muscle, by drawing the scapula upward and
backward. It receives a branch from the fifth cervical nerve, which also
supplies the muscle immediately above, the levator anguli scapule, which
arises from the neck (page 208) and is attached to the scapula between
the superior angle and the root of the spine. The smooth triangular
surface over the root of the spine has in the recent state a mucous bursa,

or a layer of loose connective tissue, over which the trapezius muscle plays
42
330 THE REGION OF THE SHOULDER.

as it passes to its insertion along the upper margin of the spine, as previ-
ously described (page 208). The spine gradually projects from the dorsal
surface, arising out of the smooth triangle at the vertebral border until it
ends in the flattened, rough, quadrilateral acromion process, which is twisted
so that it overhangs the shoulder-joint.

The superior border of the scapula extends outwardly from the superior
angle and ends in the curiously crooked projection called the coracoid
process, at the root of which there is usually a notch, the supra-scapular,
for the passage of the supra-scapular nerve, the companion vessels passing
immediately over it. This notch is often a distinct foramen, or is con-
verted into one, like similar notches elsewhere, by the presence of a trans-
verse ligament. To this ligament, or to the inner border of the supra-
scapular notch, is attached the scapular end of the omo-hyoid muscle.

The coracoid process is very much like the little finger half bent, and
extends forward over the shoulder-joint, where it can be felt during life
below the clavicle. The inner border receives the attachment of the
pectoralis minor muscle (page 255), and from its point the coraco-brachialis
and short head of the biceps muscles arise by a common tendon. The
coracoid and acromion processes have a strong fibrous band extending
between them, called the coraco-acromial ligament, which forms an arch
over the shoulder-joint and prevents the head of the humerus from being
dislocated upward.

The anterior or thoracic surface of the body of the scapula is concave,
presenting a broad sub-scapular fossa, or venter, with three or four slight
ridges at the vertebral border, which give origin to the intersections
between the bundles of fibres of the sub-scapularis muscle, which completely
occupies the fossa. Toward the root of the coracoid process this surface
of the bone is smooth and the tendon of the sub-scapularis muscle passes
over it, there being a large bursa interposed across the capsule of the
shoulder-joint to be inserted into the lesser tuberosity on the anterior part
of the top of the humerus. The fibres from the axillary border of the
fossa are inserted into the neck of the humerus two and a half centimetres,
or about an inch, below the tuberosity. The chief action of this muscle
is to rotate the head of the humerus inward. The whole of the anterior
THE REGION OF THE SHOULDER. 331

surface of the vertebral border of the scapula receives the insertion of the
serratus magnus muscle. This flat muscle forms the inner wall of the axilla
(Plate 44, Fig. 1, and Plate 45, Fig. 2). It arises by nine digitations
from the upper eight ribs (there being two attached to the second rib),
which are arranged according to the direction of the fibres into superior,
middle, and inferior portions. The superior is formed by the junction
of the slip from the first rib with the anterior slip from the second rib
by a small tendinous arch, and is inserted into. the border of the superior
angle of the scapula. The middle is made up of the posterior slip from
the second rib with slips from the third and fourth ribs, and is inserted
into the vertebral border and the neighboring fibrous arch. The inferior
is the strongest part, consisting of slips from the fifth, sixth, seventh,
and eighth ribs, and is inserted into the anterior surface of the inferior
angle of the scapula. This muscle is covered by the contents of the
axilla (Plate 45) and the skin over the side of the chest, and is sup-
plied by the posterior thoracic nerve (page 345). Its function is to
draw forward the scapula round the chest wall, but when the scapula
is fixed its action is reversed, so that it becomes a powerful inspiratory
muscle. At the external margin of the spine on the dorsal surface
beneath the acromion process there is a notch by which the supra-
spinatus and infra-spinatus fossee communicate: ‘this is called the great
scapular notch. Through this notch the supra-scapular artery passes and
establishes the important anastomosis with the dorsalis scapule and pos-
terior scapular arteries (page 342).

The anterior angle is the thickest part of the bone, and is called the
head, while the constricted portion posterior to it is the neck. The head
presents an oval shallow fossa, the glenoid cavity, which is narrower above
than it is below, and is directed vertically outward, forward, and a little
upward, for the reception of the head of the humerus. At the upper edge
is the supra-glenoid tubercle, for the attachment of the long tendon of the
biceps muscle, and at the lower edge is the rough infra-glenoid tubercle, for
the origin of the middle or long head of the triceps muscle. This fossa is
deepened in the recent state by the glenoid ligament, which consists of a
prismatic fibro-cartilaginous band continuous with the expansion of the
332 THE REGION OF THE SHOULDER.

fibres of attachment of the above-mentioned muscles round the margins,
The central portion of the body of the scapula is extremely light, some-
times being deficient in ossific matter, and the periosteum surrounding the
bone is strong and laminated, and especially developed upon the various
processes and _ borders.

The upper end of the humerus consists of a smooth hemispherical
head, directed upward, inward, and backward, to be received against the
glenoid cavity of the scapula. The constriction about the head is known
as the anatomical neck. From this the greater tuberosity extends outward.
It is a rough prominence, presenting three facets, an upper, a middle, and
a lower, for the attachments of the supra-spinatus, infra-spinatus, and teres
minor muscles, as already described. From the anterior part of the ana-
tomical neck the lesser tuberosity projects directly forward, the tendon of
the sub-scapularis muscle being inserted into it. Between these tuberosi-
ties there is a deep vertical furrow, the dicipital groove, for the accommo-
dation of the long tendon of the biceps muscle (Plate 44, Fig. 2). Below
the tuberosities, as far as the middle of the shaft, the bone is cylindrical,
and is known as the surgical neck, in consequence of the frequency with
which it is fractured.

The shoulder-joint consists of the adaptation of the smooth surface
of the head of the humerus upon the glenoid cavity of the scapula, thereby
constituting an enarthrodial or ball-and-socket joint. These bony surfaces
are each covered with articular cartilage in such a manner that it is
thickest at the margins of the glenoid cavity and thinnest at the centre,
while upon the head of the humerus the reverse is the case, the cartilage
being thicker at the centre and thinner toward the anatomical neck. The
capsular ligament is attached above to the circumference of the glenoid
cavity and below to the anatomical neck, except at its inner and lower
part, where it extends some little distance below. It is in itself a quite
weak structure, being composed of a very loose layer of fibrous tissue.
It is thickest at its upper part, where it is strengthened by the V-shaped
coraco-humeral ligament, and serves mainly as an outer layer for the
synovial membrane, offering very little security to the joint, which in
reality depends upon the great strength and number of the tendons of
THE REGION OF THE SHOULDER. 333

the muscles with which it is intimately associated. When these tendons
are completely severed, the head of the humerus will fall away from the
glenoid cavity to the extent of two and a half centimetres, or an inch, or
even more, so loose is the capsular ligament; and likewise the arm appears
to be lengthened when the muscles which ordinarily support it are para-
lyzed. In fact, the capsule is large enough to accommodate the head of
the femur, which is nearly twice the size of the head of the humerus. A
knowledge of the arrangement of the tendons about the joint is therefore
of great importance, not only in realizing the wide range of motion of:
which the joint is capable, but also in understanding how to readjust it
in case of its dislocation.

The tendons of the supra-spinatus, infra-spinatus, and teres minor
muscles, as they pass over the capsule to their respective insertions upon
the greater tuberosity, strengthen the upper and posterior part; the broad
tendon of the sub-scapularis muscle protects it on the inner part, where
it comes forward to be inserted into the lesser tuberosity; and below it
receives support from the long head of the triceps muscle. Further-
more, the long tendon of the biceps muscle, which is lodged within the
deep groove between the tuberosities, pierces the capsular ligament and
passes over the head of the humerus to the top of the glenoid cavity,
strengthens the upper anterior part of the joint, and prevents the head
of the humerus from being brought against the acromion process in the
upward movements of the arm. In fact, it is mainly by the normal
position of this tendon, assisted somewhat by the atmospheric pressure,
that the head of the humerus is retained in its natural position. Occa-
sionally the biceps tendon is dislocated out of its groove onto the inner
ridge, and abduction is limited by the great tuberosity thus corning almost
immediately in contact with the acromion process. From a careful con-
sideration of the disposition of the tendons it will be seen that they
surround the capsule, except toward the axilla, where the head of the
humerus can be readily felt. When the arm is raised and extended,
the head of the humerus rests upon the weak part of the capsule; and
it is therefore through this part, between the tendons of the sub-scapularis
and the long head of the triceps, that most of the dislocations at this
334 THE REGION OF THE SHOULDER.

joint occur. If the capsule is opened, it presents upon its interior several
folds, which have been specialized as gleno-humeral folds. The synovial
membrane is reflected upon the inner surface of the capsule and forms
fringes at the borders of these folds, and is invaginated about the biceps
tendon, which it follows as a tubular sheath down the groove to the extent
of five centimetres, or two inches. There is a constant small opening at
the upper and inner side of the capsule, which admits the tendon of the
sub-scapularis muscle, and by which the synovial membrane communicates
directly with the bursa under the tendon. There is also often an opening
from the capsule leading into the bursa beneath the tendon of the infra-
spinatus muscle. In chronic disease of the joint sinuses are readily estab-
lished in the sites of the bursal connections. There is no anatomical
communication between the capsule and the bursa under the deltoid muscle,
which is interesting because the sub-deltoid bursa is peculiarly liable to
independent disease. It is contained within an expansion of loose con-
nective tissue beneath the deltoid and overlying the tendons of the spinati
muscles. The shoulder-joint is practically a universal joint, and, as it
depends upon the arrangement and power of the surrounding tendons,
rather than upon the mechanical adjustment of the opposing bony sur-
faces, the grouping of the muscles in effecting the various movements
should be understood. Hatension is effected by the teres major, latissimus
dorsi, and the posterior portion of the deltoid. These are assisted in
raising the arm by the teres minor and infra-spinatus muscles. Flexion
is produced by the coraco-brachialis and the anterior portion of the deltoid,
aided by the pectoralis major; abduction, by the deltoid and supra-spinatus ;
adduction, by the pectoralis major, teres major, latissimus dorsi, and coraco-
brachialis. °

The shoulder is rotated outward by the infra-spinatus and teres minor,
and inward by the sub-scapularis, latissimus dorsi, and teres major. The
shoulder-joint is supplied by the circumflex nerve and circumflex artery,
which are described on page 342. The deep structures of the shoulder-
joint are protected by the great deltoid muscle, which forms a complete
shoulder-cap. It arises from the lower border of the outer third of the
clavicle, from the acromion process, and from nearly the whole of the spine
THE REGION OF THE SHOULDER. 335

of the scapula (Plate 16). This extensive origin corresponds to that of
the trapezius muscle above (page 208). The muscular fibres composing
the deltoid are very coarse, and are disposed in bundles or fascicles which
are separated by inward expansions of the strong layer of the deep fascia
enveloping the muscle upon its outer surface. The bundles thus formed by
the fibres arising from the clavicle and from the spine of the scapula gen-
erally converge from their origins to their insertions upon the lateral ridges
of the deltoid tuberosity, but those of the outer or acromial portion are
peculiarly arranged. Here there are additional fibres which originate from
the sides of the intramuscular tendinous septa in a bipenniform manner
and pass parallel to one another to be inserted by fleshy slips into the
middle ridge of the deltoid tuberosity on the outer surface of the shaft
of the humerus. The deltord tuberosity consists, therefore, of three con-
verging ridges. The tendon of insertion can be understood only by de-
taching the muscle from its origin and reflecting it. When this is done, it
will be seen that the insertion is about three and three-quarter centimetres,
or an inch and a half, in length, extending upward upon the middle of
the shaft from the deltoid ridges, whence fibrous septa are projected into
the substance of the muscle between the fibres originating from the apo-
neurotic expansions between the fasciculi. In this manner the several
fasciculi reinforce one another, and the increased number of their fibres
compensates for their length, thus greatly augmenting the functional power
of the muscle as a whole. Looked at from in front, the insertion of the
deltoid resembles the letter V. It is embraced by the fleshy origins of the
brachialis anticus muscle, and thus occasions a characteristic depression of
the overlying integument. The three parts of the muscle can act sepa-
rately in raising the arm in different directions, and they each act to better
advantage when the humerus is rotated outwardly. The power of the
deltoid depends greatly upon the scapula being steadied by the serratus
magnus, the long head of the triceps, and the middle fibres of the tra-
pezius muscles. When the whole muscle contracts, it raises the aym to
the horizontal position (at an angle of ninety degrees): beyond this it
cannot act, further elevation being effected by the serratus magnus and
trapezius, which then raise the shoulder. The deltoid muscle receives its
336 ‘THE REGION OF THE SHOULDER.

blood from the circumflex arteries (page 342), and is supplied by the cir-
cumflex nerve (page 346).

When the head of the humerus is dislocated into the axilla, the
rotundity of the shoulder is lost, the deltoid becomes flattened, and the
acromion process is rendered very prominent. In such a condition there
is beneath the latter process a marked depression, into which one or two
fingers can be inserted, constituting one of the diagnostic features of dis-
location at the shoulder-joint. Dislocation at this joint is very common.
Primarily the displacement is always downward into the axilla, because it
is caused by direct violence received upon the point of the shoulder or by
indirect violence while the upper extremity is abducted and the joint conse-
quently placed at a disadvantage, the head of the humerus readily slipping
through the lowest and weakest part of the capsule (page 332). Sometimes
the head of the bone is retained in this position, when it is called a swd-
glenoid dislocation. After leaving the capsule, however, the pectoralis
major and other muscles having free play, it is most frequently drawn
forward and inward, and assumes the character of a sub-coracoid dislo-
cation. Rarely the head of the humerus is driven backward under the
acromion upon the dorsum of the scapula (sud-spinous dislocation). In
every form of dislocation there will be flattening of the deltoid and more
or less stretching of that muscle, and consequently abduction of the arm,
with proportionate rigidity. The chief diagnostic symptoms are as follows:
the elbow stands away from the side of the body, and the hand of the
affected limb cannot be placed in the small of the back nor upon the top
of the opposite shoulder. There have been many observations regarding
the special anatomy of the various forms of dislocation at the shoulder,
but they are of no practical use, beyond the inference that the head of
the humerus, in order to be returned to its proper place, must be jirst
restored to the sub-glenoid position, and then, by circumduction or other
means, its reduction may be accomplished. The proximity of the im-
portant structures within the axilla renders them liable to injury from
pressure of the head of the humerus when it is driven against them, and
that they escape with so little damage is probably due to the relaxation
of the soft parts which follows upon the shortening of the limb.
THE REGION OF THE AXILLA. 337

Fractures involving the anatomical neck of the humerus are ex-
tremely rare, and can only be suspected, unless an opportunity is given
to explore the joint. The prolongation of the internal and lower fibres
of the capsular ligament would connect the fragments unless they were
also ruptured. The superior epiphyseal line is below the tuberosities,
just where the shaft is widest. It does not become obliterated before
the twenty-second year. The upper epiphysis may become detached prior
to this period, and simulates the condition of a fracture in the upper
part of the surgical neck of the humerus without overlapping.

In amputation at the shoulder-joint it is essential that the incisions
should be made so as to leave the division of the axillary vessels to the
last moment. Whatever method is employed, the long tendon of the
biceps muscle should be sought for, and by using its bony furrow as a
grooved director the capsule can be slit up and the joint expeditiously
opened. In the oval flap method, which the author has found to possess
many advantages, the relations of the severed vessels and nerves as they
present themselves in the flaps after amputation at the left shoulder are as
follows (Plate 50, Fig. 2). The anterior flap is formed by the pectoralis
major (No. 3), the heads of the biceps, coraco-brachialis, latissimus dorsi,
teres major, and rotator muscles. The axillary vessels (Nos. 1 and 2), the
cords of the brachial plexus of nerves (No. 11), and the inferior scapular
artery and veins (No. 12) will be found in the axillary border of this flap ;
while the long tendon of the biceps (No. 5), a branch of the anterior cir-
cumflex artery (No. 7), and the cephalic vein and the descending branch
of the acromio-thoracic artery (No. 8) occupy the acromial border of the
flap in relation to the severed clavicular portion of the deltoid muscle.
The posterior flap is formed mainly by the scapular portions of the deltoid
muscle (No. 15), with branches of the posterior circumflex vessels and
nerves (No. 14).

THE REGION OF THE AXILLA.

The region of the axilla, or armpit (Plates 44 and 45), varies
in depth with the position of the arm. It is a pyramidal space, bounded

internally by the side of the thorax, externally by the arm, and in front
48
338 THE REGION OF THE AXILLA.

and behind by prominent muscular folds. The anterior fold is formed by
the lower border of the pectoralis major muscle (page 253), while the pos-
terior fold is formed by the lower borders of the latissimus dorsi and teres
major muscles (page 329). The shin of the axilla is closely connected with
the subjacent superficial fascia, is provided with long hairs which radiate
toward the borders of the cavity, and contains numerous sebaceous glands
of a reddish-brown color, which are liable to become inflamed and pro-
duce superficial abscesses. It also has very large sweat-glands, and a
dense net-work of lymphatic vessels in the corium. There is more or less
fat in the meshes of the subcutaneous tissue. The deep fascia is called
the azillary fascia. It is very dense, and bears important relations to
the fasciz of the regions of the neck, thorax, and shoulder. It consists
of a close fibrous layer stretching across the base of the axilla, between
the anterior and posterior folds. It is continuous with the deep fascia
surrounding the pectoralis major muscle (page 255), and with the costo-
coracoid membrane above, which, since it draws up the axillary fascia
toward the clavicle, is known sometimes as the suspensory ligament of the
axilla. It produces the characteristic “hollow” of this region. The
space beneath the axillary fascia is mainly occupied by a quantity of
very loose connective tissue and fat, in which pus or extravasated blood
often collects to an extraordinary amount, being checked in its progress
toward the surface by the fascia. In consequence of the barrier which
this fascia also presents laterally, there is a tendency for unrelieved abscess
in this region to extend into the neck along the sheath of the vessels
in the direction of least resistance. In opening an axillary abscess, a
small incision should first be made through the deep fascia of the floor
of the space, upon the mner side, midway between the two axillary folds.
As soon as the pus is reached, the opening can safely be enlarged upon a
grooved director. Trifling as this operation may seem to the uninitiated,
it is fraught with danger unless due precaution is taken to avoid the
important structures on the outer and upper part of the space. The
muscles forming the posterior wall of the axilla are the latissimus dorsi,
teres major, and sub-scapularis. The anterior wall is formed by the under
surfaces of the pectoralis major and minor muscles. Upon the inner wall
THE REGION OF THE AXILLA. 339

are the four upper ribs, with their intercostal muscles, covered by the
serratus magnus. The biceps and coraco-brachialis are upon the outer
wall, between the convergence of the two axillary folds. At the apex of
the space the axillary vessels and nerves descend outwardly from the root
of the neck, whence they bring with them a funnel-shaped prolongation of
the deep cervical fascia. This communication between the neck and the
axilla constitutes the cervico-azillary passage. It is bounded by the first rib,
the clavicle, and the upper border of the scapula. In order to see the con-
tents of the axilla, the axillary fascia must be removed. Within the layers
of this fascia a small artery will sometimes be found, probably arising
from the brachial artery, crossing the floor of the space quite superficially.
It is noteworthy, as it is directly in the way of the usual incision for
opening an axillary abscess. Whenever the knife is used in this region,
great caution must be exercised, and after the preliminary incision it is
better to resort to the handle of the knife or to the finger to separate the
loose connective tissue and thus expose the lymphatic glands, vessels, and
nerves, the relations of which deserve particular attention. Not far from
the surface the posterior lateral cutaneous branches of the intercostal nerves
will be found perforating the chest wall between the digitations of the
serratus magnus muscle (Plate 45). Of these the posterior lateral branch
of the second intercostal nerve is specialized as the intercosto-humeral
nerve, because it supplies the skin of the inside of the arm as low as the
internal condyle (Plate 27, No. 41). It passes across the upper part of the
axilla, issuing from the second intercostal space. There is also an inter-
costo-humeral nerve from the third nerve, which receives a branch from
the second and accompanies it in its distribution. The anterior branches
of the above two nerves supply the skin upon the side of the chest and
on the axillary folds.

The axillary artery is the continuation of the subclavian, and
commences at the lower border of the first rib, whence it passes downward
and outward along the coraco-brachialis muscle to the lower border of the
posterior fold of the axilla. It is separated from the inner side of the
shoulder-joint by the insertion of the sub-scapularis muscle into the lesser
tuberosity of the humerus. The pectoralis minor muscle (page 255)
1,

QAO Pp wp

PLATE 46.

Figure 1.

The anterior view of the right elbow and forearm of an adult male, with the superficial fascia carefully removed to
show the relations of the superficial veins and nerves.

The median nerve in the lower third of the arm, over-
lapping the brachial artery.

. The brachial artery.

The biceps muscle.

The external brachial vein.

The external (in this case independent) cephalic vein.
The median cephalic vein.

. The musculo-spiral nerve.
. The fascia from the biceps tendon, passing beneath the

superficial veins at the head of the elbow.

. A branch of the musculo-cutaneous nerve.
10.
. The median veins (in this case double).
12.
B.
14.
15.
16.
17.
18.

A branch of the recurrent radial artery.

The radial vein.

The radial nerve.

The radial artery with its venz comites.
The tendon of the supinator longus muscle.
The median nerve, above the wrist.

The ulnar nerve.

The triceps muscle.

 

. The greater internal cutaneous nerve.

. The lesser internal cutaneous nerve.

. The internal brachial vein.

. The anastomotica magna artery.

. The basilic vein.

. Branches of the ulnar nerve.

. Branches of the internal cutaneous nerve.

. The anastomosing vein.

. Deep fascia over the flexor muscles.

. The ulnar vein.

. The flexor carpi radialis muscle.

. Branches of the musculo-spiral nerve.

. Carpal branch of the internal cutaneous nerve.
. The ulnar nerve.

. The tendon of the flexor carpi ulnaris muscle.

. The flexor sublimis digitorum muscle.

. The ulnar artery and its vene comites.

. The external carpal branch of the ulnar artery.
37.

The annular ligament.

Figure 2.

Deeper dissection of same arm as Figure 1.

The bicipital fascia and the superficial flexor muscles are removed,

while most of the superficial veins are retained to preserve their relations.

H
o

CHOIAMRA WN YE

. The brachial artery.
. The biceps muscle.

The median nerve.

The external brachial vein.
The external cephalic vein.
The median cephalic vein.

. The tendon of the biceps muscle.

. The brachial artery, surrounded by the brachial veins.
. The musculo-spiral nerve.

. The communication between the superficial and deep

veins, by the vena anastomotica.

. The anterior interosseous branch of the median nerve.
. The supinator longus muscle.

. The median vein. ;

. The anterior interosseous artery, with its vene comites.
. The radial artery, with its vene comites.

. The shaft of the radius.

. The radial nerve.

 

18.
19.
20.
21,
22,
23.
24,
25.
26.
27.
28,
29.
30.
31.
82.
33.
34,
30.

Carpal branch from the radial artery.

The triceps muscle.

The internal cutaneous nerve.

The ulnar nerve.

The basilic vein.

The internal brachial vein.

Branches of the ulnar nerve, over the internal condyle.
The cut attachment of the superficial flexor muscles.
The deeper portion of the pronator radii teres muscle.
The bifurcation of the brachial artery.

The origin of the interosseous artery.

A muscular branch from the ulnar artery.

The ulnar nerve.

The flexor carpi ulnaris muscle.

The median nerve.

The ulnar artery, with its venz comites.

The pronator quadratus muscle.

Carpal branch of the ulnar artery.
VObL +

>

Fig eB

 

 

eLLANM.D.

clu

by GeorseM

A
)

Hisht1890

Copyt

Armsirang & Ca. Lith, Boston.

oy Georce Me. CLELLAN, M D.

 

Dissected, Photographed and Colored trom \
THE REGION OF THE AXILLA. 341

passes across the middle of the artery to be inserted into the coracoid
process, so that the vessel is usually described according to its position,—
above, under, or below that muscle. In its course there are many
branches from it distributed to the neighboring regions. Above the
pectoralis minor the superior thoracic and acromio-thoracic arteries arise
independently or by a common axis. The superior thoracic passes along
the border of the pectoralis minor, and, descending between it and the
pectoralis major, supplies them both and anastomoses with branches from
the intercostal and internal mammary arteries. The acromio-thoracic
artery usually divides very near its origin, as it pierces the costo-coracoid
membrane, into several branches. They are the small thoracic or pectoral,
to the serratus magnus and pectoralis minor muscles, the descending or
thoracica humeraria (Holden), which descends in close relation to the
cephalic vein between the deltoid and pectoralis major muscles, both of
which it supplies, and the acromial and clavicular branches. The acromial
crosses the coracoid process to the under surface of the deltoid muscle, and
establishes a communication (the rete acromiale) with the posterior circum-
flex and supra-scapular arteries. The clavicular supplies the subclavius
muscle. The companion veins of these arteries terminate either in the
cephalic or in the axillary vein,—generally in the latter.

The alar thoracic artery arises variably from the axillary trunk or
from its long thoracic branch. It supplies the anterior lymphatic glands
embedded in the connective tissue of the axillary space. The long thoracic
artery (Plate 44, Fig. 1, No. 7) descends close to the lower border of the
pectoralis minor muscle. It sometimes gives off the alar artery, but its
external mammary branch is usually quite large in the female and passes
to the breast along the lower border of the pectoralis major. The short
and long sub-scapular arteries are variable in their origin. The short sub-
scapular is distributed mainly to the under surface of the sub-scapular
_ muscle. The long sub-scapular artery is the largest of all the branches
of the axillary. It descends in relation to the sub-scapularis muscle and
divides into anterior and posterior branches. The anterior or thoracic
branch descends in relation to the posterior fold of the axilla to the side
of the chest, where it ends in the serratus magnus. It also sends a small
342 THE REGION OF THE AXILLA.

twig to the inferior angle of the scapula which anastomoses with branches
from the dorsalis scapule and posterior scapular arteries. The posterior
branch of the long sub-scapular artery is called the dorsalis scapule (Plate
45, Fig. 2, No. 17). It passes into the sub-scapular triangle, which is
formed by the long head of the triceps muscle passing between the sub-
scapularis and teres major muscles to its insertion at the inferior border
of the glenoid cavity (page 854). Here it gives off a deep branch which
breaks up into smaller branches in relation to the ridges of the sub-
scapular fossa. The superior of these branches is important, because it
supplies an articular artery to the shoulder-joint and the principal nutrient
artery to the venter of the scapula. The main trunk of the dorsalis
scapule artery winds round and grooves the axillary border of the scapula
under the centre of the attachment of the teres minor muscle. Here it
supplies this muscle and the adjoining infra-spinatus muscle, and anasto-
moses with branches from the posterior circumflex and posterior scapular
arteries. The veins which accompany these arteries terminate in the sub-
scapular veins, which empty into the axillary veins.

Owing to the many sources of arterial supply to the scapula and its
muscles and their free anastomoses, the removal of the scapula, or even
of growths involving a portion of it, is attended with profuse hemor-
rhage. All the main vessels above described require a ligature in these
operations, and consequently their relative positions should be carefully
studied.

The posterior circumflex artery is nearly as large in diameter as the
sub-scapular. It arises opposite to it, and sometimes with it by a common
trunk, and passes backward, accompanied by its two veins and the posterior
circumflex nerve, round the posterior surface of the neck of the humerus,
to the under surface of the deltoid muscle. This artery establishes com-
munications with the branches from the acromio-thoracic and supra-scapular
and the ascending branch from the superior profunda, and supplies not
only the neighboring muscles, but also the head of the humerus and the
shoulder-joint. The anterior circumflex artery is much smaller than the
posterior, and passes under the coraco-brachialis and the coracoid head of
the biceps close to the anterior surface of the neck of the bone. In relation
THE REGION OF THE AXILLA. 345

to the bicipital groove this vessel gives off the little bicwpital artery, which
accompanies the long head of the biceps to the capsule of the shoulder-
joint and to the head of the humerus. It enters the capsule by a foramen
at the top of the bicipital groove. The anterior circumflex communicates
with the posterior circumflex beneath the deltoid muscle.

There is great variability in the position of the branches of the axillary
artery, and sometimes, although rarely, it furnishes the radial or the ulnar
artery to the forearm.

When the arm is extended in the supine position, a line drawn from
the middle of the clavicle to the point where the anterior axillary fold
crosses the inner border of the biceps muscle corresponds to the course
of the axillary artery. This line also indicates the position of the inter-
muscular cleft between the sternal and clavicular portions of the pectoralis
major muscle, in which the axillary artery can be most easily reached,
as it lies upon the first intercostal space below the clavicle. The point
where the pectoralis minor muscle crosses the artery may be designated by
a line drawn from the coracoid process to the junction of the third rib and
its cartilage. The artery is inaccessible for a ligature beneath the pecto-
ralis minor muscle, so that its relations above and below that muscle are of
peculiar interest to the surgeon. When tied in the upper part, the collat-
eral circulation is established through the same vessels as after the ligature
of the outer part of the subclavian artery (page 232). In the operation for
tying the lower part of the axillary artery the incision should be made
upon the inside of the bulge of the biceps muscle when the arm is ex-
tended, and by following upward along the border.of the coraco-brachialis
muscle the artery will be found enveloped in its sheath and closely
surrounded by the two brachial veins, the basilic vein, and the median
and ulnar nerves. In this relation there are often connecting links be-
tween the veins extending across the artery, and often, too, accessory slips
from the latissimus dorsi muscle to the insertion of the pectoralis major,
and therefore, in spite of the artery being more superficial in this locality,
it is very difficult of access. The collateral circulation here is similar to
that which occurs upon the ligation of the brachial artery above the origin
of the superior profunda,—zi.e., by the communication of that vessel with
344 THE REGION OF THE AXILLA.

the branches of the posterior circumflex and the neighboring muscular
arteries. If, before applying the ligature, the forearm is flexed and the
position of the arm is changed, there can be little difficulty in distin-
guishing between the artery and the nerve-cord of the brachial plexus,
which is close to it. This nerve-cord has been mistaken for the artery
in several recorded instances. :

The axillary vein is the continuation of the basilic vein upward
from the lower border of the posterior axillary fold to the outer border
of the first rib. In its course it receives as tributaries the venz comites
of the branches of the axillary artery, except the circumflex veins,
which either join the sub-scapular or empty into one of the brachial
veins. Either just before or at its termination in the subclavian vein
the axillary vein receives the two brachial veins and the cephalic vein
(Plate 45, Fig. 2). The orifices of the tributary veins are guarded by
single valves, but there are double valves at the termination of the
main trunk. The axillary vein is more superficial than the artery, and
throughout most of its course, when the arm is at the side, the vein is
in front of and internal to the artery, but when the arm is slightly raised
the vein, although still in front, is below the artery. If the arm is raised
to more than a right angle, the vein will overlap the artery above the pec-
toralis minor. Just above its commencement the axillary vein is separated
from the artery by some of the nerves of the brachial plexus. The costo-
coracoid membrane is intimately adherent to the external coat of the
axillary vein where it pierces that dense fascia to empty its blood into
the subclavian vein. This attachment serves to keep the vessel open when
it is wounded, and probably explains the great rush of blood when it is
severed. Its position also renders it liable to be influenced by the inspira-
tory movements of the chest, and thus air may be drawn into the heart
through the vessel if the latter be wounded. In amputation at the
shoulder-joint (Plate 50, Fig. 2) it is important to secure the axillary
vein with a ligature immediately after tying the axillary artery.

The brachial or axillary plexus of. nerves is formed by the
anterior branches of the fifth, sixth, seventh, and eighth cervical and
first dorsal nerves, each branch consisting of muscular and cutaneous fila-
THE REGION OF THE AXILLA. 345

ments in close association. The fifth receives a descending or communi-
cating branch from the fourth cervical above it, and then joins with the
sixth to form the upper trunk of the plexus. The seventh cervical
pursues an independent course as far as the clavicle, and is the middle
trunk, while the eighth cervical and first dorsal as they issue from beneath
the scalenus anticus muscle unite in relation to the first rib to form the
lower trunk (Plate 4, Fig. 2, and Plates 20, 25, and 33). The arrange-
ment of the nerves contributing to the plexus is variable, especially upon
the left side, but the following corresponds to most of the author’s dis-
sections. At the outer border of the scalenus medius muscle the three
great nerve-trunks divide into anterior and posterior branches. The
anterior divisions from the upper and middle trunks form the outer cord
of the plexus, the anterior division from the lower trunk furnishes the
inner cord, and the posterior divisions of the upper and middle trunks
unite behind the axillary artery to form the posterior cord, which also
receives the small posterior division of the lower trunk; but the latter is
often found passing directly to form part of the musculo-spiral nerve. At
its commencement the plexus is broad (Plate 25), but it becomes narrow
opposite the clavicle (Plate 36), and forms below it an intricate interlace-
ment about the axillary artery (Plate 45, Fig. 2) beneath the pectoralis
minor muscle. In the root of the neck the nerve-trunks receive some
filaments from the cervical ganglia of the sympathetic nerve, and the
fifth cervical nerve sends a branch to join the phrenic nerve as it
passes down over the scalenus anticus muscle (page 221). The branches
from the brachial plexus above the clavicle, besides the one to the phrenic
nerve, are small muscular nerves to the longus colli and scalehe muscles,
and a branch which pierces the ‘scalenus medius and accompanies the pos-
terior scapular artery to supply the levator anguli scapule and rhomboid
muscles. The supra-scapular nerve arises from the upper trunk of the
plexus, and passes to the superior border of the scapula beneath the supra-
scapular artery through the notch in the scapula. It furnishes nerves to
the spinati muscles and to the shoulder-joint. The posterior thoracie nerve
(or external respiratory nerve of Bell) arises usually from the upper trunk,

at the outer border of the scalenus medius, and sometimes receives a branch
44
346 THE REGION OF THE AXILLA.

from the middle trunk. It passes behind the axillary artery, and sup-
plies the serratus magnus muscle, which it enters upon the outer surface
(Plate 45, Fig. 2, No. 38). ,

The branches below the clavicle are mainly for the supply of the arm.
The external and internal anterior thoracic nerves arise by filaments from
the anterior divisions of the three trunks of the plexus. The ezternal
anterior thoracic nerve pierces the costo-coracoid membrane in close rela-
tion with the acromio-thoracic artery, and supplies the adjacent parts of the
pectoralis major muscle. The internal anterior thoracic nerve is joined by
a filament from the former, and, after passing between the axillary vessels,
supplies the pectoral muscles. The swb-scapular nerves, three in number,
arise from the posterior cord of the plexus and are distributed to the sub-
scapularis, teres major, and latissimus dorsi muscles. The nerve to the
last muscle is called the long sub-scapular nerve, and accompanies the sub-
scapular artery to the lower border of the muscle. The circumflex nerve
arises from the posterior cord anterior to the sub-scapular nerves. It is a
large nerve, and after sending a filament to the shoulder-joint it accompa-
nies the posterior circumflex artery round the surgical neck of the humerus
beneath the deltoid muscle. It divides into many branches, which supply
the skin over the deltoid and the upper and back part of the arm (Plate
‘27, No. 87). Very curiously, the branch of the circumflex nerve which
supplies the teres minor muscle possesses a small pseudo-ganglion close to
its origin. Branches also pass to the front and back parts of the capsular
ligament. The terminal branches of the brachial plexus are described
with the arm (page 357).

The lymphatic glands of the axilla (Plates 44 and 45) receive
the lymphatic vessels from the upper extremity, from the back, from the
anterior portion of the chest, and from the outer portion of the mammary
gland (page 251). They form a continuous chain with the cervical lym-
phatic glands passing beneath the clavicle to the root of the neck. They
are about a dozen in number, of variable size, and are mostly in close
relation to the axillary vein and its larger tributaries. There is also a
cluster of the glands situated more superficially than the deeper ones, and .
embedded in the loose connective tissue and fat of the axillary space. The
THE REGION OF THE AXILLA. 347

thoracic and sub-scapular arteries furnish blood to the deeper glands, while
the superficial ones are supplied by the alar thoracic artery. The lymphatic
vessels from the outer side of the arm and shoulder pass to a couple of
glands in the groove between the deltoid and pectoralis major muscles,
over the costo-coracoid membrane, near the cephalic vein. The efferent
vessels from these usually pass to the cervical glands directly, while the
lymphatic vessels from the inner side of the arm terminate in three glands
situated along the axillary vein. A gland is generally found in relation
to the sub-scapular artery, and another on the tendon of the latissimus
dorsi close to the humerus. The superficial lymphatic vessels of the
back are derived from the whole expanse of that region, from the nape
of the neck to the loins. They converge to the axilla, and end in the
glands in the upper and back part of the cavity.

The lymphatic vessels from the nipple, the areola, and the outer portion
of the breast convey their lymph to two or three glands situated upon the
serratus magnus muscle under cover of the lower border of the pectoralis
major muscle. The efferent vessels from all the axillary glands resolve
themselves into four lymph-trunks, which pass along with the subclavian
vein and terminate upon the right side in the right lymphatic duct and
upon the left side in the thoracic duct (page 318). When the axillary
glands are in a normal condition they cannot be felt through the skin;
and it is not always possible to detect them even when they are slightly
enlarged. Their secondary involvement in scirrhous disease of the breast
is so common that it is advisable in all such cases, when an operation
is resorted to, to extend the incision into the axillary space, so that the
finger can thoroughly explore the cavity. With the exception of the
removal of the chain of cervical glands from about the internal jugular
vein, there is no operation of a similar nature more trying to the skill and
patience of the surgeon than the removal of the axillary glands about
the axillary vessels. They are closely associated at all times with the
thin walls of the great veins in this region, but when implicated with
disease their relation is of the most intimate character, and they have
literally to be peeled off one by one, at imminent risk of rupturing the
veins. No rough handling of the structures in the apex of the axilla
348 THE REGION OF THE ARM.

during an operation would be countenanced by one whose scalpel had
ever unravelled the intricacies of these parts in his student days.

THE REGION OF THE ARM.

The arm extends from the axilla to the elbow. It has already been
stated (page 332) that the shape of the shaft of the humerus above the
deltoid insertion is cylindrical; below it is prismatic and slopes gradu-
ally downward and slightly forward to the lower end, where it becomes
transversely flattened (Plate 28). The central portion of the lower end
of the humerus is peculiarly formed for articulation with the ulna. It is
called the trochlea, and consists of a smooth, rounded, condyloid surface,
which is constricted at the middle so that the inner portion is somewhat
larger and projects lower than the outer. Above the constriction ante-
riorly there is a depression for the reception of the coronoid process
of the ulna when the forearm is flexed, called the coronoid fossa. Pos-
teriorly there is a similar but larger depression, the olecranon fossa, for
the olecranon process of the ulna when the forearm is extended. The por-
tion of bone between these fossee is exceedingly thin and translucent, and
sometimes perforated, forming the supra-trochlear foramen. Jutting out
from the internal portion of the trochlear surface is a prominent process,
the internal epicondyle, and to the periosteum over this process the flexor
muscles of the wrist and hand are attached. The internal epicondyle
looks directly inward when the arm hangs naturally at the side, and
occupies a lower plane than the external epicondyle, which is the corre-
sponding process upon the outer portion of the trochlear surface. The
latter is rough and comparatively short, and gives attachment to the
origins of some of the extensor muscles. Upon the outer surface of
the trochlea is a small spheroidal forward projection, called the capit-
ulum, upon which the cup-shaped depression on the head of the radius
rests and glides within the elbow-joint. The outer and inner borders
are directly continuous with the epicondyles, and are known as the ea-
ternal and internal supra-condyloid ridges. Upon the posterior surface
of the internal epicondyle there is a slight groove for the ulnar nerve.
The epicondyles are the only parts of the humerus which are subcuta-
THE REGION OF THE ARM. 349

neous, and, although the shaft of the humerus can be felt through the
soft structures, there are no other bony prominences, and therefore the
surface-marking, which is due to the contour of the various muscles, is of
particular interest in relation to the subjacent parts. This is more pro-
nounced in well-developed muscular men than among women whose arms
are rounded and of regular outline. Fat, here, as in other parts of the
body, always subdues the depressions and renders them less discernible.

The skin on the front and inner surface of the arm is especially smooth,
free from hairs, delicate, and extremely sensitive, while on the back and
outer surface it is somewhat thicker and less sensitive. The skin is also
loosely attached to the deeper parts by the subcutaneous fascia. This is
often manifest in cellulitis, and in amputation through this part of the
upper extremity the laxity of the integument allows it to be drawn away
from the muscles with very little effort. For this reason the method of
applying the knife from without inward in amputation through the arm
is suggested to those who may be called upon to do this operation with-
out much practical experience, as it secures flaps with bevelled edges (Plate
51, Fig. 1).

The triangular depression caused by the insertion of the deltoid muscle
(page 335) can generally be recognized upon the surface with ease, and, as
it indicates the precise mid-point of the shaft of the humerus, it is an
important landmark. Exactly opposite to it, upon the inside of the arm,
is the insertion of the coraco-brachialis muscle. The bulge of the biceps
muscle causes its outline to be usually well defined in the front of the arm,
so that there are furrows or depressions upon each side of it. The ouder
bicipital depression extends from the bend of the elbow to the insertion
of the deltoid, and corresponds to the position thus far of the cephalic
vein (Plate 45, Fig. 1, No. 29), which ascends above this in the groove
between the deltoid and pectoralis major muscles and empties into the
axillary vein. It is accompanied by the descending branch of the acromio-
thoracic artery and the upper external cutaneous nerve. Sometimes there
is a connecting vein between the cephalic vein and the external jugular or
the subclavian, which passes over the clavicle, and, being subcutaneous, is
readily seen during life. The inner dicipital depression is more notice-
Pi

oe 9

6.

on

se

PLATE 47.

Figure 1.

The radial border of the forearm and elbow, showing the relations of the superficial veins—the superficial fascia
being carefully removed—to the muscles and tendons.

The biceps muscle.

The basilic vein.

The external cephalic vein, a direct continuation of the | 11. The bicipital fascia.
radial vein. 12, The median vein.
Branches of the musculo-cutaneous nerve. 13. Branches of the musculo-spiral nerve.
The musculo-spiral nerve. 14, The tendon of the flexor carpi radialis muscle.
The tendon of the extensor communis digitorum mus- | 15. The tendon of the supinator longus muscle.
cle. 16. The radial nerve passing round to the back of the wrist.
The tendon of the extensor secundi internodii pollicis | 17. The tendon of the extensor ossis metacarpi pollicis
muscle. muscle. ,
The posterior annular ligament. 18. The tendon of the extensdr primi internodii pollicis
The external brachial vein. muscle.
The median nerve. 19, The radial artery, seen through the deep carpal fascia.
Figure 2.

The anterior view of the left elbow to show particularly the bicipital fascia in relation to the superficial veins and
the deep vessels and nerves. .

1. The brachial artery. 9. The biceps muscle,
2. The basilic vein. 10. The median nerve.
3, The anastomotica magna artery. 11. The brachial vein.
4. The ulnar nerves. 12, The median basilic vein.
5. The internal cutaneous nerve. ; 13. The brachial artery at the bend of the elbow.
6. The branches of the ulnar and internal cutaneous nerves 14, The tendon of the biceps muscle.

around the internal condyle of the humerus. 15. The median cephalic vein.
7. The ulnar vein. 16. The vena anastomotica.
8. The branches of the internal cutaneous nerve in the | 17. The bicipital fascia.

forearm. 18. The median vein.

2 Figure 3.
Dissection of the veins on the back of the hand and forearm, with their relations to the underlying teudons and

nerves.
1. The posterior ulnar vein. 6. The posterior radial vein.
2. The common ulnar vein. 7. The radial vein.
8. The posterior annular ligament. 8. The radial nerve.
4. The carpal branch of the ulnar nerve. 9. The radial artery.
5. The vena salvatella. 10, One of the dorsal interossei arteries.
Wore

 

 

Copyright /890,by GeoreeMc Cue. ay MD

(th, Boston.

Armstrong & Co. L

, Photographed and Colored from Nature by Georce Mc, Cret.an, M D.
THE REGION OF THE ARM. 351

able than the outer; it extends from the middle of the bend of the elbow
all the way to the axilla, and indicates the course of the brachial artery
and its companion veins and nerves.

The deep fascia of the arm is a continuation from the fascia of the
shoulder and axilla. It forms a close-fitting investment for all the mus-
cles in this region, and sends into each condyloid ridge of the humerus
strong septa which divide the muscles in front from those behind. In
certain localities it expands so as to form protected passage-ways for im-
portant vessels and nerves, as over the musculo-spwral groove on the pos-
terior surface of the humerus for the nerve of that name and the superior
profunda artery which accompanies it, and on the border of the humerus
above the internal condyle, where it sometimes forms a dense band across
the median nerve. Here its attachment to the humerus is occasionally
ossified, presenting a hook-shaped process of bone, which is then called
the supra-condyloid process. The deep fascia is also pierced here and there
by the nerves which pass down to be distributed to the forearm, and at
the middle of the internal bicipital depression there is an oval opening,
the hiatus semilunaris, for the basilic vein.

There is marked variability in the density of the deep fascia in its
different relations. Thus, over the biceps it is quite thin, but upon the
inside of the arm, where it passes between the biceps and the brachialis
anticus, it is very strong, forming a dense sheath for the brachial vessels
and nerves and binding them upon the surface of the latter muscle. At
the back of the arm the fascia constitutes a strong envelope over the biceps
muscle, and in front, as it approaches the elbow in relation to the tendon
of the biceps, it is also remarkably strong.

The biceps muscle is so called because it has a double origin. The
long head arises by a long round tendon from the top of the glenoid cavity
and the glenoid ligament, and, arching over the head of the humerus
within the capsule of the shoulder-joint, pierces the latter between the
two tuberosities and descends in the bicipital groove between them, covered
with a reflection of the synovial membrane of the joint (page 334), which
serves to lubricate it and facilitate its movements. It is held in place
by the tendon of the pectoralis major muscle, which passes over it to be
352 THE REGION OF THE ARM.

inserted into the outer ridge of the groove, being also connected to the
latter muscle by its sheath. The short head arises by fleshy and tendi-
nous fibres from the point of the coracoid process together with the
coraco-brachialis muscle (Plate 44, Fig. 2, No. 23). About the middle of
the arm the two heads unite and form a single mass of muscle, which
is subject to great variation in development in different individuals, and
terminates suddenly in a strong flat tendon. This tendon is of con-
siderable length, is subcutaneous, and can be readily felt upon contrac- |
tion of the muscle. It twists somewhat-upon itself and sinks into the
ante-cubital fossa to be inserted into the lower and posterior part of the
bicipital tubercle of the radius, a bursa being interposed between the
tendon and the front of the tubercle. Before the tendon enters the
fossa. it gives off from its inner border a semilunar fold of fascia which
protects the brachial vessels and the median nerve at the bend of the
elbow (Plates 46 and 47).

The action of the biceps muscle is to both flex and supinate the fore-
arm. The function of supination ensues upon the manner of its insertion
into the posterior part of the tubercle of the radius, and is most effectually
accomplished when the elbow is bent, because the tendon then passes at
a right angle to its insertion. The peculiar igamentous function of the
long tendon at the shoulder-joint has already been described (page 333).
The biceps receives two branches from the brachial artery. One of these
is called the vas aberrans (page 355). It enters about the middle of the
muscle, and divides within its substance into ascending and descending
branches. Each head of the muscle receives a branch from the musculo-
cutaneous nerve (page 362).

The coraco-brachiahs (Plate 44, Fig. 2, No. 7, and Plate 45, Fig. 2,
No. 29) is a slender muscle on the inner side of the short head of the
biceps, in common with which it arises by fleshy fibres from the coracoid
process of the scapula. It is inserted by a flat tendon at the middle of
the inner surface of the shaft of the humerus, just above the foramen for
the nutrient artery to that bone. This muscle is pierced by the musculo-
cutaneous nerve in its upper portion (Plate 45, Fig. 2, No. 27), which also
supplies it. Its action is to draw the arm forward and inward upon the
THE REGION OF THE ARM. 353

side of the chest. Not only is the upper portion of this muscle the guide
to the axillary artery (page 343), but, as the brachial artery is in rela-
tion to its flat tendon of insertion, it can here be effectually compressed if
the pressure is directed outward. This is the usual site for the applica-
tion of a tourniquet; but it should always be remembered that the close
relation of the median nerve (page 357) renders it liable to be included
in the pressure and therefore to cause great pain. There is a bursa inter-
posed between the tendons of the coraco-brachialis and the short head of
the biceps and the tendon of the subscapularis muscle over the head of
the humerus.

The brachialis anticus muscle arises by two fleshy portions, one upon
each side of the insertion of the deltoid, and from the lower part of the
front surface of the humerus, which it covers. Its inner border is also
connected with the septum from the deep fascia which separates it from
the triceps posteriorly. Its fibres are arranged in nearly parallel bundles,
so that they form a broad’ thick mass superposed upon the capsule of the
elbow-joint, to which it is slightly attached. Its tendon is flat, and upon
the outer border extends into the substance of the muscle. It is chiefly
inserted into the coronoid process of the ulna, and reflected upon a ridge *
from this process to the tuberosity of the ulna. It forms a pad to the
elbow, upon which the brachial vessels and the median and musculo-
cutaneous nerves are supported internally, as they pass across the joint
under protection of the expansion from the tendon of the biceps muscle.
Externally the brachialis anticus is quite superficial, and separated from
the supinator longus muscle by a furrow in which is lodged the musculo-
spiral nerve (Plate 47, Fig. 1, No. 4), from which it receives a small
branch, although its main nerve-supply is from the musculo-cutaneous
nerve upon its inner side. Its action is to flex the elbow.

The triceps extensor cubiti is so called from its triple origin and its
peculiar function of being the sole extensor muscle of the forearm. It
is situated at the back of the arm. The long or middle head arises by a
strong thick tendon from the infra-glenoid depression and the lower
portion of the glenoid ligament. It is closely connected with the capsule

of the shoulder-joint. As it passes between the tendons of the teres
46
354 THE REGION OF THE ARM.

minor and major muscles (page 329) it becomes more fleshy. The outer
head begins immediately below the attachment of the teres minor muscle,
and is itself attached all the way to the musculo-spiral groove and to
the reflection of the deep fascia. The inner head arises close to the in-
sertion of the teres major muscle, and from the posterior surface of
the humerus below the musculo-spiral groove nearly as far as the inter-
nal, epicondyle. Its fibres arrange themselves into an oblique tendon
which blends with the muscular mass composed by the union of the
fleshy portions of the other two heads about the middle of the back
of the arm. The combined tendon thus formed is thick and remark-
ably strong. It is inserted into the summit and sides of the olecranon
process of the ulna. Between the tendon and the back part of the
capsule of the elbow-joint there is a cushion of fatty tissue, which has
sometimes been described as a bursa. From the tendinous portion of the
inner head some muscular fibres pass directly to the olecranon and the
adjacent portion of the capsule, and have been specialized as the sud-
anconeus muscle. 'The musculo-spiral nerve separates the outer from the
inner heads, and sends branches to all the heads of the triceps muscle.
The brachial artery is the continuation downward of the axillary
artery. It commences at the lower border of the posterior fold of the
axilla, at the inner border of. the coraco-brachialis muscle, whence it
passes along the inner border of the biceps muscle to the middle of
the flexure of the elbow, where, opposite the head of the radius, it
divides into the radial and ulnar arteries. The above muscles slightly
overlap the artery in its course, which is at first internal to the shaft of
the humerus upon the triceps and brachialis anticus muscles and sub-
sequently gradually inclines to the front of the lower end of the bone
beneath the bicipital semilunar fascia. The brachial artery gives off
seven or eight muscular branches from its outer side to the contiguous
muscles, and four principal branches from its inner side, as follows:
The superior profunda artery usually arises from the brachial below
the teres major muscle, although it is sometimes given off in common with
the posterior circumflex from the axillary. Soon after its origin it dis-
tributes muscular branches to the deltoid, the coraco-brachialis, and the
THE REGION OF THE ARM. 355

long head of the triceps muscle; also a communicating branch to the poste-
rior circumflex, which plays an important ré/e in the collateral circulation
after ligature of the main vessel in this locality, and a nutrient branch,
which enters the upper end of the humerus beneath the outer head of the
triceps. About the middle of the arm the superior profunda subdivides
into two principal branches, one of which, the cubital, descends through
the substance of the triceps muscle to the olecranon process, where it an-
astomoses with the anastomotica magna, posterior ulnar, and interosseous
recurrent arteries, assisting in the formation of the rete olecrani; while
the other branch accompanies the musculo-spiral nerve to the outer side
of the arm, where, after piercing the intermuscular septum, it descends
deeply with the radial nerve in the furrow between the brachialis anticus
and supinator longus muscles to anastomose with the radial recurrent
artery about the externa] epicondyle.

The inferior profunda artery arises either in common with the superior
profunda or by a separate origin at the middle of the arm, and pursues
a course with the ulnar nerve through the intermuscular septum to the
interval between the internal epicondyle and the olecranon, where it also
terminates in the rete olecrani. The main nutrient artery is usually
derived from one of the muscular branches of the brachial. It pierces
the tendon of the coraco-brachialis muscle to enter the nutrient foramen,
and within the medullary canal divides into ascending and descending
branches which anastomose with the nutrient vessels derived from the
periosteum. The anastomotica magna arises from the brachial about six
centimetres, or two and a half inches, above the bend of the elbow. It
runs at first inward across the brachialis anticus muscle, and then divides
into branches, one of which descends anteriorly between the brachialis
anticus and pronator radii teres muscles in front of the internal epicondyle
to anastomose with the anterior ulnar recurrent artery, another pierces the
intermuscular septum posteriorly to anastomose with the posterior ulnar
recurrent and. inferior profunda arteries in the rete olecrani, while a third
usually arches over the olecranon fossa and joins the superior profunda
artery. Besides these regular branches of the brachial artery there is
another, called the vas aderrans, which ordinarily is quite insignificant
356 THE REGION OF THE ARM.

and arises near the origin of the superior profunda or in common with
it, and descends over the median nerve to supply the neighboring part
of the biceps muscle. This vessel occasionally plays an important réle
in replacing the brachial artery when that vessel. has undergone some
modifying change in consequence of interference with its development
during foetal life. In such cases it pursues the ordinary course of the
brachial artery, except that it is placed over instead of under the median
nerve, and it joins the radial artery, or very rarely the ulnar. It is of
variable size, and, owing to its substituting one or other of the terminal
branches of the main vessel, it occasions the condition called the high
bifurcation of the brachial. The possibility of such an occurrence should
never be lost sight of in the operation of tying the brachial artery. The
line of reference for the brachial artery is practically a continuation of
the line for the axillary artery (page 343), and may be drawn along
the internal bicipital depression from the middle of the axillary space to
the middle of the bend of the elbow. The incision should be made along
the above line, with the arm abducted and rotated outward. The basilic
vein (page 351) will be found in the superficial fascia, and can be drawn
aside. The deep fascia should be divided upon a grooved director, and
when the biceps muscle has been drawn outward the sheath of the brachial
vessels will be exposed, with the median nerve lying directly over it; and,
as the nerve may therefore receive pulsations from the artery, it requires
careful examination lest it be mistaken for the vessel itself.

After much experience as a teacher of operative surgery, the author
feels justified in stating that the inexperienced generally find more diffi-
culty in securing the brachial artery properly than in securing any other
artery in the body. This may be due to the belief that the task is an
easy one, owing to the straight course and somewhat superficial position
of the vessel. The disposition of the median nerve is most important,
and if understood it may serve as a deep guide to the artery. This
nerve in the upper part of the arm is generally at the owder side of the
artery, but it very soon approaches the sheath of the brachial vessels
and overlies it as far as the semilunar bicipital fascia, where the artery
passes to the middle of the elbow-joint, and the nerve continues, at its
THE REGION OF THE ARM. 357

inner side, to descend between the two heads of the pronator radii teres
muscle. There is an investment of the deep fascia which retains the
nerve in this relation to the sheath of the vessels even if the position of
the arm is changed in extension, but if the forearm is flexed after the
deep fascia is divided the nerve can be drawn to one side or the other
and the underlying sheath exposed. When the latter is opened, the artery
will be found with a companion vein upon each side of it. It should be
further remembered that the upper part of the artery is over the musculo-
spiral nerve, that the ulnar nerve is close to its inner side as far as the
insertion of the eoraco-brachialis muscle, and that toward the elbow the
internal cutaneous nerve is either in front of or close to its inner side.

The vene comites of the brachial artery are the continuations of the
deep radial and ulnar veins (Plate 46, Fig. 2). The internal is usually
much larger than the artery, and often overlaps it. They are frequently
united by cross veins, similar to those about the axillary artery, either in
front of or behind the artery, and they unite in a single trunk in the
axilla to empty into the axillary vein near the tendon of the sub-
scapularis muscle.

The terminal branches of the brachial plexus of nerves (page 344) are
the median, the musculo-cutaneous, the ulnar, the two internal cutaneous,
and the musculo-spiral nerves. The median nerve is composed of a plexi-
form arrangement of fibres derived from two heads which arise respectively
from the outer and inner cords of the brachial plexus and unite to form a
single nerve-cord external to the axillary artery, generally beneath the pec-
toralis minor muscle (Plate 45, Fig. 2, No. 23). In its course down the
arm the median nerve does not normally give off any branches. It is
usually at first at the outer side of the artery, near the axilla, although
not always so, and it soon overlies the sheath of the brachial vessels
until it reaches the elbow, where it is at the inner side of the artery,
as already described. The deep fibres of origin to the outer head of
the median nerve are derived from the sixth and seventh cervical nerves,
and those to the inner head are derived from the eighth cervical and
first dorsal nerves. The musculo-cutaneous nerve arises from the outer
cord of the brachial plexus in common with the external head of the
PLATE 48. °

Figure 1.

Dissection of the palm of the right hand, showing the superficial layer of the palmar fascia.

1, The abductor pollicis muscle. 7. Arch of the palmar fascia, between the metacarpal
2. Slip of the palmar fascia, passing to the proximal pha- bones of the index and middle fingers, over the

lanx of the thumb. digital vessels and nerves.
8. Lateral nerve to the thumb. 8. Tendon of the palmaris longus muscle.
4, Accessory transverse slip of the palmar fascia, arching 9. The ulnar artery, at the wrist.

over the vessels and nerves to the thumb. 10. The abductor minimi digiti muscle.
5, The princeps pollicis artery. 11. The external lateral nerve and artery to the little finger.
6. The superficial layer of the palmar fascia, showing its | 12. Arch of the palmar fascia, between the little and ring

longitudinal fibres and expansion. fingers.

18. The branches of the median nerve.
Figure 2.

Dissection of the palm of the right hand. The superficial layer of the palmar fascia is hooked aside to show the
deep layer of the fascia and the superficial palmar arterial arch.

1. The superficialis vole artery. 10. The annular ligament.
2. The abductor pollicis muscle. 11. The ulnar artery.
3. The continuation of the superficialis vole artery. 12. The ulnar nerve.
4, The deep layer of the palmar fascia, over the median | 13. The abductor minimi digiti muscle.
nerve and the flexor tendons. 14. Branches of the median nerve.
5. The flexor brevis pollicis muscle. 15. The external lateral artery to the little finger.
6. The superficial palmar arch. 16. Branch of the superficial palmar arch.
7. Digital branches of the median nerve. 17. Tendinogs insertion of the palmar fascia to the meta-
8. The superficial layer of the palmar fascia, hooked aside. carpal bone of the ring finger.
9. Branches of the median nerve, dividing at the cleft of 18. Superficial flexor tendon to the ring finger.
the fingers into digital nerves. 19. Digital nerves from the median nerve.
Figure 3.

Dissection of the palm of the right hand, showing the position of the superficial arterial arch and the relations

of its digital branches to the nerves and flexor tendons.

1. The flexor carpi radialis tendon. 11. Anastomosing branches of the digital arteries, across
2. The median nerve, above the annular ligament. the phalangeal joint.
3, The abductor pollicis muscle. 12. Aponeurotic arch.
4, The median nerve, below the annular ligament. 13. Terminal arterial plexus.
5. The princeps pollicis artery. 14. The ulnar artery.
6. The flexor tendon to the index finger. 15. The annular ligament.
7. Aponeurotic arch. 16. The ulnar nerve.
8. Sheath of flexor tendons. 17. The superficial palmar arch.
9, Aponeurotic arch. 18. Superficial flexor tendon.
10. The subdivision of the superficial flexor tendons, to be | 19. Aponeurotic arch of the fiexor tendon to the ring
inserted in the sides of the second, or intermediary, finger.
phalanx. 20. Deep flexor tendon of the ring finger.
Figure 4.

Dissection of the palm of the right hand. The tendons are cut away to show the deep palmar arterial arch and its

relations, etc.

. The median nerve, above the annular ligament.
. The opponens pollicis muscle.

The abductor pollicis muscle.

. The superficialis vole artery.

The flexor brevis pollicis muscle.

Branch of the median nerve to the thumb.

The adductor pollicis muscle.

The tendon of the flexor longus pollicis muscle.
The cut ends of the flexor tendons,

. Sheath of the flexor tendons,

. Aponeurotic arch.

. Terminal arterial plexus.

Be
BE Semsagpwye

. The ulnar nerve.
. The ulnar artery.

. The annular ligament.
. The median nerve, below the annular ligament.
. The flexor brevis minimi digiti muscle.

. The deep palmar arch,

. The superficial palmar arch.

. The cut ends of the flexor tendons.

. Aponeurotic arch.

. Insertion of superficial flexor tendon into the sides of
the intermediary phalanx of the ring finger.

. Terminal arterial plexus,
 

 

Copyright/890,by GeorseMc Cutan, M.D

Dissected, Photographed end Colored trom Nature oy Georce Mc. Crean, M OD, i
THE REGION OF THE ARM. 359

median nerve, at the outer side of the axillary artery. It pierces the
coraco-brachialis muscle and passes obliquely to the septum between the
biceps and brachialis anticus muscles. Above the outer side of the elbow
the nerve pierces the deep fascia between the tendon of the biceps and
supinator longus muscles, and becomes subcutaneous beneath the median
cephalic vein (Plate 46, Fig. 1, No. 9). It supplies branches to the
coraco-brachialis, the coracoid head of the biceps, and the brachialis an-
ticus muscles. This nerve is sometimes derived from the median nerve,
or, if it is absent, the median nerve distributes the branches ordinarily
supplied by it,—the whole of the outer cord of the brachial plexus, in
such instances, contributing to the formation of the median. Division
of the musculo-cutaneous nerve at its origin will result in paralysis of
the flexor muscles at the elbow. Its fibres have been traced to the fifth
and sixth cervical nerves.

The ulnar nerve arises from the inner cord of the brachial plexus
in common with the internal head of the median nerve and the internal
cutaneous nerve. In its course normally this nerve gives off no branches
in the arm. At first it is internal to the brachial artery, but it soon leaves
it to accompany the inferior profunda artery, with which it pierces the
intermuscular septum fourteen centimetres, or about five inches, above
the elbow, and descends on the inner head of the triceps muscle to reach
the space between the internal epicondyle and the olecranon. Here it is
accommodated in a shallow groove upon the back of the epicondyle
(page 348), and can be felt through the skin.

The internal cutaneous nerve, after its origin from the inner cord of
the brachial plexus, descends at first beneath the deep fascia on the inner
side of the brachial artery. About the middle of the arm it pierces the
fascia at the hiatus semilunaris, which also admits the basilic vein (page
351), and divides into anterior and posterior branches. The anterior
branch passes under the median basilic vein and supplies the skin on
the forearm as far as the wrist, where it communicates with cutaneous
branches of the ulnar nerve. The posterior branch soon subdivides
into several branches, one of which is distributed to the back of the
internal epicondyle and communicates with the lesser internal cutaneous
360 THE REGION OF THE ARM.

nerve, and another to the back of the forearm as far as the wrist, above
which there is a connection between it and the ulnar nerve. The fibres
composing both the ulnar and the internal cutaneous nerves are originally
derived from the eighth cervical and first dorsal nerves. The lesser
internal cutaneous nerve (of Wrisberg) arises also from the inner cord
of the brachial plexus, receiving its filaments from the first dorsal nerve.
It is at first upon the inner side of the-axillary vein, and near the anterior
fold of the axilla it usually unites with the posterior division of the lateral
cutaneous branch of the second intercostal nerve, or intercosto-humeral
nerve (page 339): the compound nerve thus formed pierces the deep
fascia and supplies the skin of the inside of the arm as far as the elbow.

The musculo-spiral nerve arises from the posterior cord of the brachial
plexus, in common with the circumflex nerve (page 346), their original
filaments being derived from the sixth, seventh, and eighth cervical and
first dorsal nerves. The musculo-spiral nerve is the largest of the nerves
of the arm. It descends behind the upper part of the brachial artery and
passes between the external and the internal heads of the triceps muscle,
winding obliquely round the back of the shaft of the humerus with the
superior profunda artery in the musculo-spiral groove. Thence it pierces
the intermuscular septum and enters the furrow between the brachialis
anticus and supinator longus muscles, both of which it supplies upon
the outer side of the lower third of the arm, where it divides into two
terminal branches, the radial and posterior interosseous nerves. In the
first part of its course, behind the brachial artery, the musculo-spiral
nerve gives off branches as follows: the nerve to the long head of the
triceps; the posterior wmternal cutaneous nerve, which supplies the area
of skin behind that supplied by the intercosto-humeral nerve; the nerve
to the wmner head of the triceps, from which a little branch sometimes
passes to join the ulnar nerve; the nerve to the anconeus muscle; the
nerve to the outer head of the triceps; and the posterior eaternal cutaneous
nerve, Which usually arises from the main nerve within the musculo-spiral
groove and subdivides into two branches, the superior of which becomes
superficial below the deltoid insertion and supplies the skin of the arm
between that point and the elbow external to the cephalic vein. The
THE REGION OF THE ARM. 361

inferior branch descends within the superficial fascia of the forearm and
supplies the skin over the ulna (page 378). It is interesting to note that
the musculo-spiral nerve supplies a// the extensor and all the supinator
muscles, except the biceps. In consequence of its close connection with
the humerus, this nerve is frequently injured by contusions, or in fractures
at the middle of the shaft of the bone.

Fracture of the shaft of the humerus is a very common accident, both
from direct and from indirect violence, but much undue stress has been laid
upon the influence of muscular action upon the displacement of the frag-
ments of the bone. In fact, marked displacement is rarely met with, not-
withstanding the possibilities usually ascribed to the injury with reference
to its occurrence above or below the insertion of the deltoid muscle. The
weight of the arm tends to overcome displacement, and seldom allows much
shortening. In the treatment of all fractures of the arm it is of the
utmost importance that both the shoulder-joint and the elbow-joint should

_be properly supported, so as to maintain the fragments in perfect line.
Non-union would probably be far less common if this were understood.
In amputation through the middle of the arm by the antero-posterior oval-
flap method, the relations of the important parts as they appear in the flaps
when made upon the deft arm are as follows (Plate 51, Fig. 1). The ante-
rior flap consists chiefly of the biceps muscle (No. 1), while the posterior
flap is composed chiefly of the triceps muscle (No. 5), containing the
anastomotica magna artery (No. 11). Between the fiaps on the inner side
are the ulnar nerve (No. 4), the median nerve (No. 3), and the brachial
vessels (No. 8). On the outer side, in the angle between the flaps will be
found the severed superior profunda artery (No. 9) and the musculo-spiral
nerve (No. 10).

At birth the ossification of the shaft of the humerus is nearly completed,
although the extremities are entirely cartilaginous. Bone is not developed
in the head before the second year, or in the tuberosities before the third
year. There is generally but one,centre of ossification for the two tuber-
osities, but there may be one for each tuberosity. The bicipital groove
is produced by the constant and forcible impression of the long tendon of

the biceps muscle on the growing bone. About the fifth year the centres
46
362 THE REGION OF THE ELBOW.

for the head and tuberosities coalesce and form the upper epiphysis, which
is not united to the shaft until about the twenty-second year. The radial
portion of the articular surface of the lower end of the humerus is de-
veloped by a centre of ossification in the third year, and the ulnar surface
does not begin to ossify before the twelfth year. The internal epicondyle is
formed about the fifth year, and the external epicondyle in the fourteenth
year. The epicondyles and the trochlear surface become united about the
seventeenth year and form the lower epiphysis, which generally unites
with the shaft a year later. It should be noted that after the sixteenth
year the growth of the humerus chiefly depends upon the upper epiphysis.

THE REGION OF THE ELBOW.

The elbow is formed by the lower end of the humerus and the upper
end of the ulna, which are so adapted to each other that they establish
a hinge-joint of very considerable strength, by which the arm is con-
nected with the forearm. The peculiar conformation of the lower end |
of the humerus has already been described (page 348). The upper end
of the ulna is one of the most remarkable portions of the skeleton, and
possesses many singular features. It consists of two conspicuous processes
separated by a deep hollow. The process which extends backward is
called the olecranon, because it forms the prominence of the elbow. It
is a thick, strong, bony eminence ending in a curved tip which is received
into the olecranon fossa of the humerus when the forearm is extended.
The base of the olecranon process is constricted where it joins the ‘shaft,
corresponding to the line of the olecranon epiphysis, and is the usual
seat of fracture when this part of the bone is broken. The upper pos-
terior surface of the olecranon is somewhat square-shaped, and presents
a rough impression for the attachment of the triceps muscle (page 354).
The anterior surface is smooth, and forms the upper part of the deep
hollow called the greater sigmoid cavity, which articulates with the
trochlear surface on the humerus. The bottom of this cavity is marked
transversely by a line, which indicates the constriction at the base of
the olecranon above referred to. The cavity terminates below in the
coronoid process, the broad projection from the shaft of the ulna which
THE REGION OF THE ELBOW. 363

curves upward and ends in a point which rests in the coronoid fossa
of the humerus when the forearm is flexed. The base of the coro-
noid process is thick and directly continuous with the shaft of the ulna.
There is no epiphysis for this process, and its fracture is hardly possible.
The brachialis anticus muscle is attached to the base of the process
and contiguous part of the shaft. Upon the outer surface of the coro-
noid process there is a narrow oblong hollow, called the lesser sigmoid
cavity, in which the adjacent head of the radius rolls. The upper end of
the radius, although it is present within the elbow-joint, does not properly
take part in the function of that joint. The contiguous portions of the
elbow are peculiarly adapted to the retention of the upper end of the radius
in position, so that the function which it possesses in relation to the hand
through the wrist-joint may be maintained and act harmoniously with the
movements at the elbow. The upper end of the radius is called its head.
It consists of a round disk with a cupped depression which glides upon
the capitulum on the outer condyloid surface of the humerus. The inner
part of the marginal surface of the head is held in contact with the
lesser sigmoid cavity of the ulna, in the ordinary position of the forearm,
by means of the orbicular ligament. In the rotation of the radius the
greater part of the margin of the head may revolve within the cavity.
Below the head the bone is cylindrical and constricted, forming the
neck, which joins the shaft at the prominent ¢ubercle on the inner
side of the bone, at the posterior and under surface of which the
tendon of the biceps muscle is attached.

The elbow-joint is a ginglymus or hinge joint. The sigmoid cavities
of the ulna and the trochlear surface of the humerus are covered with a
layer of articular cartilage, as are also the depression and margin of the
head of the radius. As stated above, the latter is present at the elbow
in order merely that its function of rotation may be properly adjusted to
the contemporaneous movements of the ulna. It is therefore not attached
to the humerus by any special ligament, but with the ulna it is firmly
held in close relation by the orbicwlar ligament, which forms a sort of
collar round the neck of the radius, its ends being attached to the anterior
and posterior borders of the lesser sigmoid cavity. This constitutes the
364 THE REGION OF THE ELBOW.

superior radio-wlnar joint, the chief function of which is to prevent the
biceps muscle from dislocating the radius forward. The lower margin of
the orbicular ligament is quite straight, and much narrower than the upper
part, which is looser’ and blends with the fibres of the anterior and external
portions of the capsular ligament surrounding the elbow. The capsular
ligament is of unequal density, and is attached to the humerus over the
coronoid fossa in front, to the margins of the olecranon fossa behind, and
on each side to the lower surface of the epicondyles. Below, the capsule
is attached to the ulna on the external borders of the olecranon and coronoid
processes, and to the inner edge of the greater sigmoid cavity, and exter-
nally it is connected with the upper part of the orbicular ligament.
The capsular ligament, is strengthened by accessory fibres, which are
sometimes specialized as anterior, posterior, internal lateral, and external
lateral ligaments. They are inseparable from the rest of the capsule, but
it is important to note their peculiarities, as they in a measure limit the
extent of motion at the joimt. The anterior Ligament consists of an
oblique band of fibres extending from the internal epicondyle to the
outer part of the coronoid process and the adjacent orbicular ligament.
They assist in preventing over-extension. A few of the fibres of inser-
tion of the brachialis anticus muscle are attached to this part of the
capsule, so that in flexion the. latter is drawn upward from between the
bones. The internal lateral ligament consists of strong fibres which pass
from the internal epicondyle in a radiating manner, some being attached
to the coronoid process and some to the olecranon process, while a small
band of fibres extends transversely between the two processes across the
internal notch of the greater sigmoid cavity, thus affording protection to
the small vessels which here enter the joint. From the internal lateral .liga-
ment the flexor sublimis digitorum muscle arises (page 381). The fibres
composing the external lateral ligament pass from the external epicondyle
to the orbicular ligament, and receive the origin of the extensor communis
digitorum and supinator brevis muscles. The posterior ligament is very
weak, and is composed of thin, loose fibres which extend overthe back of
the joint from the margin of the olecranon fossa to the borders of the
olecranon process. As some’of the deep fibres of the triceps are inserted
THE REGION OF THE ELBOW. 365

into it, it is drawn upward with the contraction of that muscle. “When
the capsule is opened, several quite large fatty masses are usually found
contained within the folds of the synovial membrane, and occupying the
several fossee on the end of the humerus and the notches at the sides of
the greater sigmoid cavity of the ulna. The synovial membrane lines
the entire capsule, and is widest and loosest beneath the tendon of the
triceps muscle, as is demonstrated by the enlargement on each side of
the olecranon in cases of synovitis. It is well to note here also that in
all cases of chronic distention of the elbow-joint from disease the posi-
tion of semi-flexion is assumed, which naturally enables the joint to hold
the greatest amount of fluid. The inner surface of the orbicular liga-
ment is also provided with a reflection of the synovial membrane, which
facilitates the rotation of the head of the radius. There are several smaller
folds of the membrane in relation to the orbicular ligament. One projects
between the head of the radius and the capitulum, and another between
the lower border of the lesser sigmoid cavity and the neck of the radius.
The latter restrains somewhat the movements of pronation and supination.
The movements of flexion and extension at the elbow are probably not
hindered by the olecranon and coronoid processes of the ulna, because their
respective fossee on the humerus receive them completely; but the liga-
ments and tendons in front of and behind the joint exert a considerable
degree of restraint. A knowledge of this fact is of great importance in
the treatment of all injuries about the elbow, as the thickening resulting
from plastic inflammation occurring in such cases about these ligaments
and tendons is very apt to produce ankylosis. It is one of the reasons
why early and repeated passive motion should be resorted to upon the
subsidence of acute inflammatory symptoms in every case of sprain or
fracture at the elbow.

In consequence of the obliquity of the trochlear surface of the lower
end of the humerus, when the elbow is extended and the hand supinated
the forearm diverges from the line of the arm at an angle of about ten
degrees. A line drawn through the epicondyles on the lower end of the
humerus will form a right angle with the axis of the arm, but an obtuse
angle with the axis of the forearm. ‘This explains why in flexion the
1.
2.
3.
4.
5.
6.
7.

© oO

PLATE 49.

Figure 1.

Dissection of the muscles of the right forearm and hand in pronation to show the relations of the extensor tendons
of the thumb to the radial artery.

The tendon of the biceps muscle.

The supinator longus muscle.

The extensor radialis longior muscle.

The extensor communis digitorum muscle.

The tendon of the extensor radialis brevior muscle.

The posterior annular ligament.

The tendon of the extensor secundi internodii pollicis
muscle.

. The tendon of the extensor radialis longior muscle.

. The tendon of the extensor indicis muscle.

10. The tendon to thé index finger from the extensor com-

1,
2.
3.
4,
5.
6.
i.

~

io}

munis digitorum muscle,

11. The tendon of the middle finger.

12. The flexor carpi radialis muscle.

13. The flexor sublimis digitorum muscle.

14, The tendon of the flexor carpi radialis muscle, at the

wrist.

15, The extensor ossis metacarpi pollicis muscle,

16. The extensor primi internodii pollicis muscle.

17. The radial artery.

18. The abductor brevis pollicis muscle.

19. One of the tendons of the adductor interosseous muscle

to the middle finger, blending with the tendon of the
common extensor muscle.

Figure 2.

Dissection of the muscles and tendons of the back of the right forearm and hand, in extension.

The internal condyle of the humerus.

9. The extensor communis digitorum muscie.

The extensor carpi ulnaris muscle. 10. The supinator longus muscle.
The extensor communis digitorum muscle. 11. The extensor carpi radialis longior muscle.
The extensor minimi digiti muscle. 12. The extensor ossis metacarpi pollicis muscle.
The posterior annular ligament. 18. The tendon of the extensor radialis brevior muscle.
The tendon of the extensor radialis brevior muscle. 14. The extensor primi internodii pollicis muscle.
The tendon to the little finger from the common exten- 15. The extensor secundi internodii pollicis muscle.
sor muscle. 16. The abductor pollicis muscle.
The tendinous slip connecting the tendons to the middle
and ring fingers.
Figure 3.

Dissection of the tendons on the back of the left hand, showing the relations of the nerves and arteries,

. The extensor ossis metacarpi pollicis muscle.

. The extensor primi internodii pollicis muscle.

. The extensor secundi internodii pollicis muscle.

. The tendon of the extensor carpi radialis brevior

muscle.

. The tendon of the extensor carpi radialis longior

muscle.

. Branches of the radial nerve to the thumb and index

finger.

. The posterior annular ligament. |
. The common nerve to the adjacent sides of the thumb

and index finger.

. The abductor pollicis muscle.

10.

16.

i.

18,

. The nerves to the adjacent sides of the index and mid-
dle fingers.

. Thetendon of the index finger in its aponeurotic sheath.

. The extensor carpi ulnaris muscle.

. The shaft of the ulnar.

. The third dorsal interosseous muscle,

. The branches of the ulnar nerve to the ring and little
fingers.

Common nerve to the adjacent sides of the ring and
middle fingers.

The tendon to the middle finger from the common
extensor muscle.

One of the dorsal interossei arteries.
Plate49

au
ph

ua

Fig |

 

 

Copyright/890,by Geor6eMc Cet An, M.D.

Armstrong & Co Lith. Boston.

Dissected, Photographea ard Colored from Nature by Georce Mc. Cretan, M D0.
THE REGION OF THE ELBOW. 367

forearm inclines inward, so that the hand is brought toward the middle
line of the body, and also why it is not possible for the hand to be
placed fiat upon the shoulder of the same side. When the forearm is
extended, the epicondyles of the humerus and the olecranon process of
the ulna will be found to lie in a direct transverse line, but when it is
flexed these points form a triangle, the olecranon being brought forward
in front of the transverse line through the epicondyles. The olecranon
process is nearer to the internal than to the outer epicondyle. When the
olecranon is very prominent, its summit will be found in extreme exten-
sion above the transverse line. These bony prominences constitute the
chief landmarks of this region, and, as they can always be felt through
the skin, their relation in flexion and extension, as above indicated, should
be carefully noted in all injuries to the elbow. It may also be observed that
here, as in all other joints, much uncertainty may be removed by reference
to the similar features upon the opposite limb.

The skin over the front of the elbow is very thin and fine, and, although
there may be more or less fat in the subcutaneous tissue, the relations of the
tendon of the biceps muscle can generally be easily recognized; whereas
behind, over the olecranon, the skin is loosely attached with a thickened
and roughened cuticle, which in extension is puckered into transverse
wrinkles. In front of each elbow there is upon the outer side a promi-
nence corresponding to the bulging of the mass formed by the supinator
longus and extensor muscles, and upon the inner side there is a prominence
caused by the pronator radii teres and flexor muscles. Between these the
tendon of the biceps’ muscle descends into the ante-cubital fossa, thus
formed, and in well-developed arms a groove is noticeable extending
upward on each side of the tendon to blend respectively with the outer
and inner bicipital depressions. The outer border of the tendon of the
biceps can be distinguished better than the inner, owing to the reflection
from the latter of the semilunar bicipital fascia.

The superficial veins at the bend of the elbow, usually described
as presenting an M-shaped figure, are not always so arranged, because
the veins are liable to great diversity in their disposition (Plates 45,
46, and 47) over the bicipital fascia. The deviation is most common
368 THE REGION OF THE ELBOW.

upon the radial side, in consequence of the radial tributary veins bemg
deficient. Ordinarily the radial veins from the radial side of the forearm
pass upward to empty into the cephalic vein (page 349), and the ulnar
veins empty into the basilic vein (page 351), while the anterior median
vein ascends from the wrist to the bend of the elbow, where, after receiving.
the blood from the deep veins of the forearm by means of the vena anas-
tomotica (Plate 46, Fig. 2, No. 10, and Plate 47, Fig. 2, No. 16), it
divides into two branches, respectively known as the median basilic and
median cephalic veins. The median basilie vein generally occupies the
inner bicipital groove and joins the posterior ulnar vein above the internal
epicondyle as it empties into the basilic vein, while the median cephalic
vein follows the outer bicipital groove and joins the radial veins to form
the cephalic vein. These veins can usually be distinguished through the
integument if there is not a great deal of fat. The median basilic vein,
owing to its larger size, its prominence, and its comparatively fixed rela-
tions, has been usually selected for venesection in this region. Its course is
over the bicipital fascia, and corresponds so closely to that of the brachial
artery beneath the fascia that it may in some thin individuals receive the
pulsations from the artery.

The strength and denseness of the bicipital fascia depend upon the
general muscular development, as is the case with the expansions of the
deep fascia elsewhere. Occasionally at the elbow ¢wo median basilic veins
are found (Plate 46). Branches of the internal cutaneous nerve usually
pass close to the inner side of the median basilic vein, while filaments of
the musculo-cutaneous nerve pass to the skin of the forearm at its outer
side. Beneath the superficial fascia the relations of the vessels and nerves
on either side of the tendon of the biceps muscle are of great interest.
In the outer groove between the tendon and the supinator longus muscle
are the terminations of the musculo-cutaneous and musculo-spiral nerves,
and the superior profunda and radial recurrent arteries (Plate 46, Fig. 1,
No. 10). In the inner groove beneath the bicipital, fascia are the median
nerve, the brachial artery and its two companion veins, and the communi-
cation between the anastomotica and anterior recurrent ulnar arteries. The
median nerve at the elbow is at the ulnar side of the brachial artery, and
THE REGION OF THE ELBOW. 369

descends beneath the fascia between the two heads of the pronator radii
teres muscle (page 379), having previously distributed branches to the
superficial flexor muscles and to each head of the pronator. The dbra-
chial artery at the elbow passes beneath the bicipital fascia to the middle
of the joint, where opposite the head of the radius it bifurcates into the
radial and ulnar arteries. As the brachialis anticus muscle passes over
the elbow-joint to be inserted into the coronoid process of the ulna, it
supports the termination of the brachial artery, besides serving as a
covering to the joint. In forcible flexion of the elbow it is possible
effectually to compress the artery between the masses of muscle, but
such pressure, necessarily involving the median nerve also, is so painful
that it cannot be endured more than a short time. When the bicipital
fascia is removed, the origins of the brachial veins from the deep vense
comites of the vessels of the forearm and their relations to the brachial
artery are exposed (Plate 46, Fig. 2, No. 8). Between the olecranon
process and the internal epicondyle the ulnar nerve is lodged in a
groove, which is subcutaneous (page 359). It is in close relation with
the posterior recurrent ulnar artery. Sometimes the ulnar nerve passes
in front of the epicondyle instead of behind it. Just below the external
epicondyle there is a depression which is always to be seen even when
there is much fat in the subcutaneous tissue. This depression adds
much to the graceful contour of this part of the forearm, and it is
most marked when the latter is extended. The depression corresponds
to the interval between the supinator longus and extensor carpi radialis
muscles and the external border of the anconeus muscle. It is im-
portant surgically, as the head of the radius can be felt in it when the
bone is rotated, and because it thus affords a means of distinguishing
the line of the elbow-joint. If the forearm is placed in the position
of extreme pronation, the tubercle of the radius can be felt below the
head. The superficial lymphatic vessels of the forearm accompany the
superficial veins toward the inner side of the elbow, and terminate in a
lymphatic gland situated just above the internal epicondyle. This gland
is apt to be involved in any septic affection of the fingers or hand, and

should be remembered, as it is the lowest gland in the upper extremity.
47
370 THE REGION OF THE ELBOW.

There are three bursw about the elbow, one between the attachment
of the tendon of the biceps and the tubercle of the radius, a small
one occasionally over the internal epicondyle, and a large one over the
olecranon process. The latter is frequently enlarged, and when inflamed
may affect the joint, as there is a communication between it and the syno-
vial membrane. ‘The elbow-joint is supplied by filaments from both the
ulnar and the median nerve. In some injuries to the joint severe pain is
experienced in the parts of the forearm corresponding to the distribution
of these nerves. The anastomoses of the arteries about the olecranon
process and the posterior part of the capsule of the elbow establish the
rete olecrant. The vessels forming it are derived from the anastomotica
and superior and inferior profunda arteries, which are branches of the
brachial artery, and from the posterior ulnar recurrent and interosseous
recurrent arteries. It is important to note that their disposition is such
that the circulation through them is not interrupted by the tension of
the superficial fascia in extreme flexion of the elbow, when the current in
the brachial artery at its bifurcation may be arrested by pressure. It
should be observed also that the arteries about the internal epicondyle
are more numerous than those about the external.

The commonest form of dislocation of the elbow is where the bones
of the forearm are driven backward upon the lower end of the humerus.
In such cases, when the displacement is complete, the coronoid process
will be found opposite the olecranon fossa, with the head of the radius
projecting behind the external epicondyle. The anterior and _ lateral
ligaments of necessity are torn, the orbicular is rarely affected, and the
posterior may or may not be torn, according to the nature and direc-
tion of the violence. The tendon of the biceps appears like a tense cord
drawn over the trochlear surface of the humerus, while the attachment: of
the brachialis anticus is usually ruptured. The median and ulnar nerves
are necessarily stretched.

Fractures of the lower end of the humerus which involve the elbow-
joint occur most commonly in young persons. They are caused by direct
violence received upon the point of the elbow. Sometimes the olecranon
process is driven so forcibly into the olecranon fossa that the end of the
THE REGION OF THE ELBOW. 371

humerus is split across transversely at its base, or it may be complicated by
a vertical separation of the condyloid portions of the bone, thereby con-
stituting a T-shaped fracture. Of the two epicondyles, it may be said that
the external, on account of its slight prominence and construction, is very
rarely if ever broken by itself, whereas the internal often suffers fracture.
The latter, prior to the age of eighteen years, may be detached at its epiph-
ysis (page 362). There is seldom displacement following fracture of the
internal epicondyle, as it is enveloped by the dense aponeuroses of the
common flexor muscles of the forearm. In children, when there is a sepa-
ration of the lower epiphysis of the humerus there is naturally very little
deformity, in consequence of the epiphyseal line being almost wholly
within the capsule of the elbow. Fracture of the olecranon process occurs
most frequently just above the constriction through the greater sigmoid
cavity, and corresponds to the epiphyseal line. The degree of displace-
ment depends upon the extent to which the periosteum and ligaments are
ruptured, and the consequent unrestricted contraction of the triceps muscle.
Fracture of the coronoid process of the ulna, or of the head or neck of
the radius, can hardly occur except in severe injuries attended with dislo-
cation and extensive contusion, owing to their anatomical relations.

The relations of the parts as they are found in the flaps after ampu-
tation at the elbow-joint by the antero-posterior flap method (on the left
side) are as follows (Plate 51, Fig. 2). The anterior flap is composed
chiefly of the biceps and brachialis anticus muscles, and contains the
severed median nerve (No. 1), and the brachial artery (No. 2) and its
veins (No. 3). In relation to the internal epicondyle are the ulnar nerve
‘and the posterior recurrent ulnar artery, while the musculo-spiral nerve
is in close proximity to the external epicondyle, and the radial recurrent
artery is in the outer angle of the flaps. The posterior flap is com-
posed of the integument and the tendon of the triceps muscle (No. 12),
the latter attached to the severed olecranon process of the ulna. At
the inner border of the posterior flap there is a recurrent branch of
the ulnar artery, and in the inner angle between the flaps is the
anastomotica magna artery.

In resection of the elbow there is always danger of injuring the ulnar
372 THE REGION OF THE FOREARM.

nerve, owing to its close relation to the internal epicondyle and the difficulty
of detaching the soft structures from that bony prominence. It is very
important to preserve the periosteum over the olecranon and the strong
fascia over the anconeus muscle, so that the triceps may not be altogether
severed from the ulna. ‘The relations of the parts exposed in the procedure
by a posterior vertical incision (on the Jefé side) are as follows (Plate 52,
Fig. 6): the severed tendon of the triceps (No. 2) will be seen just above
the trochlear surface of the lower end of the humerus (No. 3); upon the
outer side of the olecranon process, which is denuded of its periosteum
(No. 8), are the head of the radius (No. 4) and the radial recurrent artery
(No. 5), while upon the inner side are the ulnar nerve (No. 7) and the
‘posterior ulnar recurrent artery (No. 9).

As an illustration of the possible degree of injury which the elbow
may recover from without loss of power or motion, the author may be
justified in noticing in this connection a case recently under his care.
The patient, a young man aged twenty-one years, received fractures of
the internal epicondyle and the upper end of the ulna below the coro-
noid process in consequence of a fall upon the elbow while it was in a
semi-flexed position. Seven weeks later, when he was regaining the use
of the elbow, after constant passive motion, he met with another fall and
fractured the olecranon of the same elbow through the greater sigmoid
cavity. Owing probably to the passive use to which the triceps had
been so recently subjected, and certainly to the extensive laceration of the
ligaments and the periosteal connections, the process was drawn a hand’s
breadth away from its proper site. The local contusion and extravasation
in both instances were unusually great, but, by careful perseverance, within
two months complete use of the joint was obtained, both as to power and
as to motion, and measurement proved that the olecranon was consolidated
again with the ulnar shaft without any separation,—an unusual feature.

THE REGION OF THE FOREARM.

The shafts of the radius and the ulna, beyond their upper extremities,
already described with the elbow, extend side by side to the wrist, and are
peculiarly formed, not only to support the soft structures of the forearm,
PLATE 50.

Figure 1.

The relations of the structures involved in the operation of trephining the skull, as in a case of cortical epilepsy.
The disk of bone has been removed and the pia mater-’partially detached to expose the convolutions on the right hemi-
sphere, supposed to include the centre of the movements of the hand, and especially of the thumb.

1. The scalp flap, including the periosteum, reflected from
the bone.

2. The skull, with the temporal ridge plainly showing.

38. The upper cut end of the temporal artery.

4. The fissure of Rolando, in this case joining the horizon-
tal branch of the fissure of Sylvius.

5. The flap of dura mater, with the cut branch of the
middle meningeal artery seen through it.

6. A branch of the middle cerebral artery, lodged in the
posterior part of the horizontal branch of the fissure
of Sylvius.

7. A cut scalp artery, branch of the posterior temporal

. artery.

8. The lower cut end of the temporal artery.

9. The lower part of the anterior central, or ascending
frontal, convolution.

10. The lower part of the posterior central, or ascending
parietal, convolution.

Figure 2.

Amputation at the left shoulder-joint by the oval-flap method (of Larrey), showing the relations of the parts exactly
as they appear after the completion of the operation. The anterior flap is formed by the pectoralis major, the heads of
the biceps, the coraco-brachialis, the latissimus dorsi, the teres major, and the rotator muscles of the joint. The posterior

flap is formed mainly by the deltoid muscle.

. The axillary vein.

. The axillary artery.

. The cut pectoralis major muscle.

. The glenoid cavity of.the scapula, covered with its ar-
ticular cartilage.

. The glenoid, or long, head of the biceps muscle.

. The clavicular portion of the deltoid muscle.

. A branch of the anterior circumflex artery.

. The cephalic vein and the descending branch of the
acromio-thoracic artery.

Pwr

mMnaIna

9. One of the brachial veins.
10. The latissimus dorsi and teres major muscles.
11. The brachial plexus of nerves.
12. The inferior scapular artery and veins.
13. A portion of the capsular ligament.
14. The posterior circumflex vessels and nerve.
15. The cut deltoid muscle.
16. The position of the sub-deltoid bursa.
e50 Neral

 

PRO ee

 

Copyright /890,by GeoreeMe Cet an, MD,

 

MD.

 

 
THE REGION OF THE FOREARM. 375

surface bends back again to be received upon the depression on the inner
border of the lower end of the radius. The internal border of the ulna
is irregular, being rounded and smooth above and roughened below, while
the external or radial border is provided with a sharp edge, except at the
lower fourth of the bone. The lower extremity. of the ulna is very small,
and terminates in a hollow depression adapted to the triangular fibro-
cartilage which intervenes between it and the wrist-joint. From the
posterior border of the lower end, on the little-finger side, extends a small
blunt-pointed bony projection, called the styloid process of the ulna. This
is placed a little lower than the rounded bony prominence or head of the
ulna, which is received against the depression on the radius, already men-
tioned, and forms the inferior radio-ulnar joint. This joint is completed
below by the upper surface of the triangular cartilage (page 397), and is
surrounded with a capsular ligament, which is especially loose anteriorly.
Some of the fibres of this capsule have been specialized, according to their
relative positions, as the anterior and posterior radio-ulnar ligaments.
They are continuous with the capsule of the wrist-joint proper. The
opposing surfaces of the ulna and the triangular fibro-cartilage are not
moulded to each other, and the intervals between them are filled by a
loose fold of synovial membrane, called the membrana sacciformis. The
shafts of the two bones of the forearm are connected by the oblique and
interosseous ligaments. The oblique ligament extends from the lower sur-
face of the tuberosity of the ulna downward and outward to the shaft of
the radius below the bicipital tubercle. It is not always present, and is
regarded as a specialization of the fascia covering the supinator brevis
muscle, which arches over the insertion of the tendon of the biceps.
The interosseous ligament, or interosseous membrane, as it is sometimes
called, consists of several layers of fibres, which pass chiefly obliquely from
the sharp internal edge of the radius to the contiguous border of the ulna.
This ligament is deficient above, to the extent of about two and a half
centimetres, or an inch, below the tubercle of the radius, so that that process
can have free play in the rotation of the bone on the ulna. In relation to
the extensor muscles of the thumb there are additional fibres derived from
their sheaths, which cross one another between the bones of the forearm.
376 THE REGION OF THE FOREARM.

The interosseous ligament, besides offering a broad surface for the attach-
ment of the deep flexor and extensor muscles (page 383), strengthens the
two bones and enables the hand to support a weight or to push against an
object in extension, as when the ulna and the humerus are in a direct line,
constituting the hwmero-ulnar shaft. The movements of pronation and
supination take place between the bones of the forearm, about an axis
which corresponds to a line drawn from the head of the radius through
the lower end of the ulna and the metacarpal bone of the ring finger.
Pronation is mainly limited by the lower two-thirds of the interosseous
ligament, the inner part of the posterior carpal ligament, and the opposi-
tion of the bones. Supination is checked partially by the lowest part of
the interosseous ligament and the internal lateral carpal ligament, and par-
tially by the catching of the posterior edge of the ulnar depression of the
radius upon the tendon of the extensor carpi ulnaris muscle, which passes
over the groove on the back of the styloid process of the ulna. Owing to
the loose capsular ligament about the inferior radio-ulnar joint, there is
always a slight lateral motion between the bones at this articulation in the
rotation of the radius. It should be remembered that the interosseous space
is larger below than above, and that it is narrowest in complete pronation
and widest in supination ; and, further, that the bones of the forearm can be
_ said to be parallel to each other only when they are held half-way between
pronation and supination, or when the forearm is at right angles with the
arm and the palm of the hand is turned upward. In the treatment of
fractures of the forearm too great attention cannot be given to the proper
adjustment of the bones so as to secure the preservation of the interosseous
space from infringement, because such infringement is almost certain to be
followed by a proportionate degree of loss of the rotating power of the
wrist. In this connection it should be noted that the shafts of the radius
and ulna vary in size relatively to each other according as they are con-
sidered near the elbow or near the wrist, the radius increasing and the ulna
decreasing from above downward. This is well seen upon section of the
bones, as in an amputation anywhere in this region (Plate 51, Fig. 8).
Both bones are also nearer to the posterior than to the anterior surface of
the forearm through their whole extent.
THE REGION OF THE FOREARM. 377

The internal and posterior surfaces of the ulna are wholly subcu-
taneous, and the lower part of the external surface of the shaft of the
radius, as well as its head, can be readily felt through the skin,—the
intervening portion of the radius being covered by the thick mass com-
posed of the supinator longus and extensor carpi radialis muscles. The
shape of the circumference of the upper portion of the forearm naturally
depends upon the degree of muscular development, being generally oval
in the male and round in the female and the child. In both of the
latter the contour of the limb is influenced by the presence of a greater
proportionate amount of fat upon the anterior and posterior surfaces. The
variability in the transverse width in the upper part of the forearm is
chiefly due to the degree of development of the muscles which take
origin from the surfaces about the epicondyles of the humerus, the mass
upon the radial side being the larger, already referred to as being more
pronounced upon the posterior surface. On the lower third of the radial
border the extensor muscles of the thumb produce a slight elevation as they
pass obliquely downward (Plate 49). Above the middle of the forearm
the muscles are always more developed anteriorly than they are posteriorly,
while below it, where the muscles become tendinous, the two bones are
more equally covered by the soft parts both anteriorly and posteriorly.

The skin, like that of the arm, is thinner, more sensitive, and more
loosely attached by the superficial fascia to the deep fascia on the front
and inner surface of the forearm than upon the back and outer surface.
The superficial veins, lymphatic vessels, and cutaneous nerves are within the
layers of fatty and connective tissue which compose the superficial fascia.
The veins can usually be readily seen through the skin, passing upward
from the wrist to the elbow. On the anterior surface the superficial
median vein ascends along the front of the forearm, while upon the ulnar
surface are usually a small superficial anterior ulnar vein and a larger
posterior ulnar vein. ‘The superficial radial veins commence at the radial
dorsal plexus of the hand and ascend by several branches over the lower
part of the posterior or dorsal surface of the forearm (Plate 47, Fig. 3),
and then wind round the radial border to empty with the other superficial

veins into the venous trunks at the front of the elbow, already described
48
378 THE REGION OF THE FOREARM.

(page 367). Besides these there are many superficial communicating
veins which connect the median with the ulnar and radial veins at dif-
ferent points in the front of the forearm. It is noteworthy that the
dorsal surface to the extent of ten centimetres, or four inches, below the
olecranon process is comparatively free from superficial veins. It is also
a fact often unheeded, that the greater part of the blood from this region
is returned by the surface veins, so that any undue or improperly-applied
pressure by splints or bandaging may result in cedema.

The cutaneous nerves of the forearm are derived from the branches
of the musculo-cutaneous, the external cutaneous branch of the musculo- -
spiral, and the internal cutaneous nerves, which supply special areas and
establish communications between their ultimate filaments. On the anterior
surface below the elbow, the anterior branch of the musculo-cutaneous
(page 357) supplies the radial border of the forearm as low down as the
wrist (Plate 27, No. 56). About opposite the middle of the radius this
nerve gives off the posterior branch, which winds backward to supply the
skin on the dorsal surface as far as the wrist, where it joins with filaments
from the radial and external cutaneous branches of the musculo-spiral
nerve. A few of the lower filaments pass across the ball of the thumb
and communicate with the palmar branch from the median nerve and
the radial nerve in that locality. In relation to the elevation caused by
the extensor muscles of the thumb the radial nerve becomes superficial,
and curves over the radius to supply the back of the hand and the fingers
(Plate 47, Fig. 1, No. 16, and Plate 53, Fig. 2). The external cutaneous
branches of the musculo-spiral nerve (page 360) supply some filaments to
the skin over the front of the forearm which join with fibres from the
anterior division of its inferior branch, and some filaments to the outer
and back part of the forearm, from the elbow to the wrist, by the pos-
terior division. On the ulnar side the anterior branch of the internal
cutaneous nerve (page 359) supplies the strip of skin over the ulna as
far as the wrist. Below the inner side of the elbow the posterior branch
passes backward to supply the upper portions of the posterior surface of
the forearm. The dorsal branch of the ulnar nerve becomes subcutaneous
close to the styloid process of the ulna (Plate 47, Fig. 3, No. 4), and dis-
THE REGION OF THE FOREARM. 379

tributes filaments over the back of the hand, which join with the terminal
filaments of the external and internal cutaneous nerves about the wrist.

The deep fascia of the forearm is directly continuous with that of
the arm, and forms a dense, close-fitting aponeurotic sleeve about the
soft structures, being peculiarly modified above and below so as to con-
tribute to the power of the muscles in their contraction and to restrain
and preserve the position of the tendons. It is mainly composed of
obliquely decussating fibres, which are reinforced in certain localities,
as in front of the elbow, by fibres from the tendons of the biceps and
brachialis anticus muscles, and at the wrist, where it forms the posterior
annular ligament and contributes to the anterior annular ligament. The
deep fascia is further attached to all the bony processes which are sub-
cutaneous, especially to the epicondyles, the olecranon, and the inner border
of the shaft of the ulna. The under surface of this fascia divides into
septa, which not only separate the individual muscles from one another
but also furnish to each of them additional surfaces for the origin of
their fibres. It is perforated at intervals by the various cutaneous vessels
and nerves.

The muscles of the forearm are disposed in two groups, an anterior
group, consisting of the flexors and pronators, which are attached about
the internal epicondyle of the humerus (page 348), and a posterior, con-
sisting of the extensors and supinators, which are attached to the external
epicondyle and the condyloid ridge above it. Each group further consists
of two layers, superficial and deep. The superficial layer of the anterior
group comprises five muscles, which are arranged in the following order
from within outward: the pronator radii teres, the flexor carpi radialis,
the palmaris longus, the flexor sublimis digitorum, and the flexor carpi
ulnaris.

The pronator radw teres muscle arises by two distinct portions or
heads, the most superficial being attached to the internal supra-condyloid
ridge and to the adjacent intermuscular septum, and also, sometimes, to the
supra-condyloid ligament (page 351), and the deeper portion by a thin
tendon from the inner side of the coronoid process of the ulna. The
fibres of these two portions unite and pass obliquely to be inserted by a
380 THE REGION OF THE FOREARM.

flat tendon into the oblique line and the pronator impression on the outer
side of the radius. This muscle forms the inner border of the ante-cubital
fossa at the elbow, and is supplied by twigs from the median nerve, which
descend between its two portions (page 369). The special function of the
pronator teres is to rotate the radius on the ulna, in conjunction with the
pronator quadratus (page 384).

The flexor carpi radialis muscle arises from the common tendon about
the internal epicondyle, from the intermuscular septa on each side of it,
and from the overlying deep fascia. Its fibres pass obliquely outward and
end in a long tendon, which is at first flat and becomes narrow toward the
wrist, where, after crossing over the anterior annular ligament, it continues
beneath the short flexor muscles of the thumb, through a fibrous arch in
relation to the trapezium, and is inserted into the base of the metacarpal
bone of the index finger. In the lower part of the forearm the tendon
of this muscle is at the inner side of the radial artery and its veins, the
tendon of the supinator longus being at the outer side (Plate 46, Fig. 1,
No. 14). Between the tendon and the trapezium there is usually a bursa.
There is sometimes an accessory muscle beneath the flexor carpi radialis,
which arises from the radius and is inserted into the metacarpal bone of
the middle finger, being also connected with the other muscle by a few
fibres at its insertion. The function of the flexor carpi radialis is to flex
the wrist and to abduct the hand, or, acting from below, it may assist in
flexing the elbow. It is supplied by the median nerve.

The palmaris longus muscle is occasionally absent, and when present
is always small. Its fibres unite into a slender flat tendon, which de-
scends usually along the middle of the forearm upon the flexor sublimis
muscle to the wrist, where, after passing over the annular ligament, it
becomes continuous with the palmar fascia (Plate 48, Fig. 1, No. 8).
In some instances the tendon of the palmaris longus is attached to the
anterior annular ligament, without extending to the palmar fascia. Its
muscular portion is subject also to great variety of development. The
flexor carpi ulnaris muscle has a double origin, from the back of the
internal epicondyle by a flat tendon, and by an expansion of the fascia
over the olecranon, so that they form an arch under which pass the
THE REGION OF THE FOREARM. 381

ulnar nerve and ulnar recurrent artery. This muscle also takes origin
from the fascia attached to the upper two-thirds of the ulna. The fibres
from these sources present a penniform arrangement, as they enter a tendon
on the radial side, which, after passing over the anterior annular ligament,
is inserted into the pisiform bone, and to the fibrous expansion stretching
across the unciform bone to the base of the metacarpal bone of the little
finger. In the lower two-thirds of the forearm the ulnar artery, with its
companion veins and the ulnar nerve, is placed between the tendons of
the flexor carpi ulnaris and flexor sublimis muscles, the former muscle
in reality overlapping the artery until within a short distance above the
wrist (Plate 46, Fig. 1, No. 33). In relation to the annular ligament
the ulnar vessels and nerve are protected by a fibrous expansion which
extends between the ligament and the tendon of the flexor carpi ulnaris.
This muscle receives twigs from the ulnar nerve as the nerve passes be-
tween its two portions above. Its function is to flex and adduct the wrist.

The flexor sublimis digitorum muscle is situated beneath the other
muscles of the superficial layer, and arises by three separate portions,
—one large, tendinous, and fleshy, from the internal epicondyle and the
adjacent part of the capsular ligament of the elbow and from the inter-
muscular septa between it and the two carpal flexor muscles; one, small
and tendinous, from the inner side of the coronoid process above the
pronator teres; and another, thin, broad, and fleshy, from the oblique
ridge on the front of the radius, extending from the bicipital tubercle to
about two and a half centimetres, or one inch, below the insertion of the
pronator teres, which partly overlaps it. The fibres from these different
sources combine into one muscle, which passes down the middle of the
forearm and subdivides into fowr distinct slips which terminate in four
tendons arranged in two superposed pairs as they pass beneath the an-
nular ligament into the palm. The superficial pair of tendons are con-
tinued to the middle and ring fingers, while the deeper pair go to the
index and little fingers. All these tendons within the palm are placed
beneath the branches of the median nerve and the ulnar artery (Plate
48, Fig. 3). Each of the tendons of the flexor sublimis muscle, as it
enters the aponeurotic sheath which encloses it in relation to the meta-
PLATE 5Bl.

Figure |.

Amputation through the middle of the left arm by the antero-posterior oval-flap method, showing the proper rela-
tions of the vessels and nerves to the humerus, in a well-developed man, aged forty-eight years.

on

1. The anterior flap, composed chiefly of the biceps mus- . The posterior flap, composed chiefly of the triceps
ele. muscle.

2. The flap of the periosteum, which was dissected from 6. Section of the left humerus, at its middle.
the anterior surface of the humerus before the saw 7. The medullary canal of the humerus.
was applied to the bone. 8. The brachial artery and veins.

83. The median nerve. 9. The superior profunda artery.

4. The ulnar nerve. 10. The musculo-spiral nerve.

11, The anastomotica magna artery.

Figure 2.

Amputation at the left elbow-joint by the antero-posterior flap method (of Dupuytren), showing the relations of the
severed structures immediately after the completion of the operation. The olecranon process of the ulna is retained
to preserve the function of extension of the triceps muscle.

1. The median nerve. 8. The musculo-spiral nerve.
2. The brachial artery. 9, The radial artery.
3. The brachial vein. 10. The lower end of the humerus, showing the trochlear
4. The ulnar artery and the ulnar nerve. surfaces of the condyles covered with articular car-
5. The anastomotica magna artery. tilage.
6. One of the recurrent branches of the ulnar artery. 11. The section through the greater sigmoid notch of the
7. The anterior flap, composed chiefly of the biceps and _ olecranon process of the ulna.

brachialis anticus muscles. 12. The posterior flap, composed of integument and the

tendon of the triceps muscle.

Figure 3.

Amputation through the middle of the left forearm by the antero-posterior oval-flap method, showing the relations
of the severed structures on completion of the operation.

'
1, The superficial median vein. 6. The radial artery and veins, and the radial nerve.
2. The anterior flap, composed chiefly of the flexor mus- 7. Section through the middle of the left radius.

cles. 8. The interosseous artery and the interosseous nerve.
3, The median nerve. 9. The posterior flap, composed chiefly of the extensor
4. Section through the middle of the left ulna. muscles. .
5. The ulnar artery and veins, and the ulnar nerve. 10. The superficial radial vein.

N. B.—These amputations were all done by means of a long, stout, straight bistoury, applied from without inward,
which gives a bevelled appearance to the flaps, overcomes the retraction of the skin, and renders unnecessary the after-
retrenching of the muscles. In each instance the vessels were left in the wound, as they would be before the application
of the ligatures, and the nerves have been left as they were severed by the knife.
Vou I

 

 

Copyright/890,by GeorceMc CLeu an MD.

ture by Georce Me. Cretzan, MD. Armstrong k hk

Dissected, Photographed aro’ Colored from h

 
THE REGION OF THE FOREARM. 383

carpo-phalangeal joint of its special finger, divides into two lateral slips,
which diverge opposite the middle of the first or proximal phalanx so
as to allow the corresponding tendon of the flexor profundus muscle to:
pass between them. The two lateral slips of the superficial tendon
closely embrace the deep tendon, and pass behind it in such a way
that their component fibres decussate before they separate again to be
finally inserted into the sides of the second phalanges (page 404). The
action of the flexor sublimis muscle is to flex the second joint of the
fingers. The different portions of the above muscle are supplied by the
median nerve.

The muscles of the deep layer of the anterior group of the forearm are
the flexor profundus digitorum, the flexor longus pollicis, and the pro-
nator quadratus. The flexor profundus digitorum muscle is the thickest
individual muscular mass in this region. It arises from the inner two-
thirds of the anterior surface of the ulna as far as the origin of the pro-
nator quadratus muscle, and from the interosseous ligament in relation to
the ulna. The fleshy mass resulting from the fibres thus arising soon
divides into two portions, the outer one of which separates from the inner
and main portion above the middle of the forearm and continues inde-
pendently to its insertion into the index finger, while the fibres composing
the inner portion are inserted into three flat tendons which pass side by
side upon the same plane with their fellow-tendons to the index finger
beneath the annular ligament, under the tendons of the flexor sublimis
muscle. About the middle of the first or proximal phalanges of the
fingers the deep tendons perforate the superficial tendons, to be inserted
finally into the bases of the third or ungual phalanges (page 404). The
tendons of the flexor profundus muscle serve to flex the finger-tips. Its
nerves are branches of the interosseous branch of the median nerve and
the ulnar nerve.

The flexor longus pollicis muscle arises mainly from the anterior part
of the shaft of the radius, below the oblique line and above the pronator
quadratus muscle, and from the adjacent part of the interosseous ligament.
It sometimes also receives a few fibres of origin from the coronoid process.
The fleshy fibres, becoming thicker toward the wrist, terminate in a tendon,
384 THE REGION OF THE FOREARM.

which passes under the annular ligament and between the two portions of
the flexor brevis, to be inserted into the base of the last phalanx of the
thumb. It strongly flexes the thumb, and receives its nerve from the
interosseous branch of the median nerve.

The pronator quadratus muscle is a square muscle arising tendinously
from the lower fourth of the oblique line on the ulna, and from the strong
fascia covering its anterior surface. Its fibres pass transversely to their in-
sertion into the lower fourth of the anterior surface and contiguous outer
border of the radius. Its function is to pronate the radius in conjunction
with the pronator teres muscle. The interosseous branch of the median
nerve also supplies it.

The muscles of the superficial layer of the posterior group of the fore-
arm are seven in number, and are arranged in the following order from
the radial to the ulnar border: the supinator radii longus, the extensor
carpi radialis longior, the extensor carpi radialis brevior, the extensor com-
munis digitorum, the extensor minimi digiti, the extensor carpi ulnaris, and
the anconeus. The supinator radii longus muscle arises by fleshy fibres
from the external condyloid ridge of the humerus as high up as the
musculo-spiral groove. It forms the outer boundary of the ante-cubital
fossa of the elbow, and is the most external of the muscles covering the
radial border of the forearm (Plate 49, Fig. 1, No. 2, and Fig. 2, No. 10).
This muscle terminates about the middle of the forearm in a flat tendon
which is inserted into the outer side of the base of the styloid process of
the radius. At its insertion it is covered by the tendon of the extensor
ossis metacarpi pollicis muscle (Plate 49, Fig. 2, No. 12). This muscle
assists the anterior muscles in flexing the forearm, but it acts as a supi-
nator upon the hand. It is supplied by a branch of the musculo-spiral
nerve before its division.

The extensor carpi radials longior muscle arises from the lower part of
the external condyloid ridge and the septum intervening between it and
the extensor brevior muscle. It soon ends in a flat tendon which is over-
lapped by the supinator longus, and, passing beneath the extensor muscles
to the thumb, it traverses a groove on the outer and posterior surface of
the lower end of the radius, to be inserted into the radial side of the
THE REGION OF THE FOREARM. 385

carpal end of the metacarpal bone of the index finger. The tendon of
this muscle occupies the second groove in the posterior annular ligament.
Its nerve is derived from the musculo-spiral nerve.

The extensor carpi radialis brevior muscle arises with the preceding
muscle from about the external epicondyle, the intermuscular septa, and
the adjacent part of the capsular ligament of the elbow. It is shorter and
thicker than the extensor longior muscle, and its fibres terminate upon the
under surface of a flat tendon below the middle of the forearm, where it
is overlapped by the extensor longior. The tendon passes beneath the
extensor muscles of the thumb, being accommodated in a special groove in
the posterior surface of the lower end of the radius, and is inserted in the
radial side of the base of the metacarpal bone of the middle finger. It is
supplied by the posterior interosseous nerve. The tendons of both of the
radial extensor muscles have usually small burse interposed between them
and their insertions. They are peculiarly enclosed in a synovial sheath as
they pass under the extensor muscles of the thumb, which allows them to
play freely under these (page 888). Their function is to extend the wrist.

The extensor communis digitorum muscle arises from the lower part
of the external epicondyle, the intermuscular septa, and the overlying
expansion of the deep fascia. It divides on the back of the forearm into
three portions, which terminate in tendons at different points and pass
under the annular ligament posterior to the radius to the back of the hand,
whence they are distributed to the fingers, the third tendon dividing so that
it is distributed to both the ring and the little finger. Below the annular
ligament the tendons become broad and flat and diverge from one another
toward the knuckle-joints of the fingers, where they change in character,
becoming thicker and narrower, and give off lateral expansions, which pass
to the sides of these joints and thus form the lateral metacarpo-phalangeal
ligaments (Plate 49, Fig. 2). On the back of the hand the two middle
tendons generally pass over the corresponding metacarpal bones, while the
tendon to the index finger passes obliquely across the space between the
first and second metacarpal bones, and the tendon to the little finger,
smaller than the other, continues in close relation to that of the ring

finger until just above the metacarpo-phalangeal joint, where it diverges
49
386 THE REGION OF THE FOREARM.

abruptly to pass to its insertion. These tendons are often connected by
accessory slips—vincula—above the knuckle-joints. They are subject to
great variety, but they generally exist as strong slips extending from each
side of the tendon of the ring finger to the adjacent tendon (Plate 49,
Fig. 2, No. 8), so that this finger does not ordinarily admit of independent
extension. The tendon of the index finger is usually free. On the back
of each finger the common extensor tendon, after giving off the bands
which serve as lateral ligaments to the metacarpo-phalangeal joint, is
continued as the digital aponeurosis, into which the tendons of the corre-
sponding lumbrical and interosseous muscles are inserted in relation to the
second or medial phalanx (page 403), where the aponeurosis divides into
three slips, the middle one of which is attached to the base of the medial
phalanx, while the two lateral slips join in front of the latter and are in-
serted into the upper end of the third or ungual phalanx. This muscle is
supplied by the posterior interosseous nerve. Not only is the function of
this muscle to act as a general extensor of the fingers, but it can also act
so as to extend the first phalanges while the second and third are flexed,
and to extend the second and third phalanges while the first are flexed.

The extensor minimi digitt muscle arises from the external epicondyle
and the adjacent intermuscular septa, and its fibres are arranged in a long
slender bundle terminating in a tendon, which passes down the back of
the forearm close to the tendons of the common extensor muscle, but
occupying a separate compartment in the annular ligament, posterior to
the inferior radio-ulnar joint. On the back of the hand the tendon
divides into two slips which pass to the little finger, the slip on the
radial side being joined by the tendon from the common extensor, already
described, and then the tendons expand over the phalangeal joints and ter-
minate in the same manner as the other extensor tendons of the fingers.
It is supplied by the posterior interosseous nerve, and its special function
is to extend the little finger independently.

The extensor carpi ulnaris muscle arises from the common tendon about
the external epicondyle, from the septum between it and the preceding
muscle, and from the posterior border of the ulna in immediate proximity
to the origins of the flexor carpi ulnaris and flexor profundus digitorum
THE REGION OF THE FOREARM. 387

muscles. The fibres combine into a strong, broad tendon which is ac-
commodated in a groove on the posterior surface of the ulna close to its
styloid process, with which it is connected by a lateral expansion of fascia,
and is finally inserted, after passing through a separate compartment in
the posterior annular ligament, into the ulnar side of the base of the
metacarpal bone of the little finger. There is also a fibrous expansion
connecting its tendon with the extensor aponeurosis at the base of the:
little finger. The tendon is surrounded by an extension of the synovial
membrane of the wrist as it lies in the groove on the ulna. When the
forearm is in the position of full pronation, the end of the ulna can be
felt and seen projecting between the tendons of the extensor carpi ulnaris
and extensor minimi digiti muscles. There is usually a bursa placed
beneath the tendon and the end of the bone. The posterior interosseous
nerve supplies its proper nerve, and its function is to extend the hand
toward the ulnar side.

The anconeus muscle is small, triangular, and placed at the external
and posterior part of the elbow, arising by a tendon from the back of
the external epicondyle and the contiguous portion of the capsule of the
elbow-joint, from which diverging fibres pass to be inserted into the tri-
angular surface on the upper fourth of the ulna. It is subcutaneous, and
receives a special branch from the musculo-spiral nerve, which descends
to it through the inner portion of the triceps muscle just above it. This
muscle may be regarded as an extension of the triceps on to the forearm,
which it assists in extending the elbow.

The muscles of the deep layer of the posterior group of the forearm are
the supinator radii brevis, the three extensor muscles to the thumb, and
the extensor indicis. The supinator radi brevis muscle arises beneath the
mass of extensor muscles, from the lower and posterior part of the external
epicondyle, from the external lateral ligament where it blends with the
orbicular ligament, and from the roughened surface of the ulna below
the lesser sigmoid cavity. The fibres of this muscle wind over the neck
and upper part of the shaft of the radius and are inserted into the radius
between the bicipital tubercle and the attachment of the pronator teres
muscle. Occasionally there is a slip for this muscle attached specially
388 THE REGION OF THE FOREARM.

to the orbicular ligament. The supinator brevis is supplied by the pos-
terior interosseous nerve (page 394), and acts as a powerful supinator of
the radius.

The extensor ossis metacarpi pollicis muscle is situated immediately below
the supinator brevis, and arises from the ulna below that muscle, from the
interosseous ligament, and from the opposite surface of the radius. It
descends obliquely, crossing over the radial carpal extensor muscles (Plate
49, Figs. 1, 2, and 3), about seven and a half centimetres, or three inches,
above the wrist, passes through the annular ligament, and is inserted into
the base of the metacarpal bone of the thumb, usually sending a slip to
the trapezium. The extensor primi internodii pollicis muscle arises from
the radius and the interosseous ligament just below the preceding muscle,
which it accompanies through the annular ligament to be inserted into
the base of the first phalanx of the thumb (Plate 49, Fig. 2, No. 14).
This muscle is interesting as being peculiar to the human hand. The
extensor secundi internodw pollicis muscle partially overlaps the preceding
muscle, arising from the ulna below the extensor ossis metacarpi, from the
interosseous ligament, and from the sheath of the extensor minimi digitt
muscle. Its tendon passes independently through the annular ligament,
in a distinct groove on the posterior surface of the radius, passes obliquely
across the radial extensor tendons, and continues over the metacarpal bone
and first phalanx of the thumb to be inserted into the base of the second
or last phalanx (Plate 49, Fig. 1, No. 7). These tendons severally extend
the portion of the thumb to which they are distributed. They can be
readily distinguished through the skin, and the hollow produced by the
extensor primi and extensor secundi tendons (the tabatiére anatomique) is
interesting because the radial artery here passes across its floor (Plate 49,
Fig. 1, No. 17) to enter into the palm (page 414). The eatensor indicis
muscle arises from the posterior surface of the ulna, below the extensor
secundi pollicis, and from the adjacent part of the interosseous ligament.
Its tendon passes beneath the annular ligament in the same groove on the
end of the radius with the tendon of the extensor communis muscle. It
proceeds to the metacarpo-phalangeal joint of the index finger, where it is
joined to the tendon from the common extensor (Plate 49, Fig. 1, No. 9).
THE REGION OF THE FOREARM. 389

This muscle is supplied by the posterior interosseous nerve, and its func-
tion is to enable the index finger to be extended independently.

The radial artery is the smaller of the two divisions of the brachial
artery (page 354). It commences about opposite the head of the radius,
and continues in the same line as the brachial artery as far as the wrist,
being upon the radial side of the forearm, and for the most part between
the supinator longus and flexor carpi radialis muscles. In the upper part
of its course it is deeply situated between the pronator radii teres and
the supinator longus, the fleshy border of the latter muscle usually over-
lapping it. This artery is superficial to the extent of eight centimetres, or
a hand’s breadth, above the wrist, and rests upon the lower part of the
anterior surface of the shaft of the radius (Plate 46, Fig. 2, No. 16), so
that it can be easily distinguished and compressed, and is therefore chiefly
used as the most convenient vessel for examining the arterial pulse.

- The branches of the radial artery in the forearm are the recurrent,
superficialis vole, muscular, and carpal. The radial recurrent artery is
of variable size, arises below the elbow, and ascends between the supi-
nator longus and brachialis anticus muscles, supplying in its course the
two supinators and the two radial extensors (Plate 46, Fig. 1, No. 10).
It inosculates with the superior profunda artery (page 354). The arteria
superficialis vole is variable both as to size and as to origin, and is some-
times absent. It usually arises from the radial artery near the wrist, where
it turns to pass under the extensor muscles of the thumb. It runs over
the anterior annular ligament (Plate 48, Fig. 2, No. 1) and above or
through the muscles of the ball of the thumb, to anastomose generally
with the superficial branch of the ulnar artery and establish the superficial
palmar arch (Plate 48, Fig. 4, No. 4). There are nine or ten muscular
branches, which furnish blood to the muscles on the radial border of the
forearm. The anterior and posterior carpal arteries are small branches
which usually leave the radial artery below the pronator quadratus and
join the ramifications of the neighboring arteries in the anterior and pos-
terior rete carpt.

The radial artery is accompanied by the two deep radial veins, or vene
comites, one on each side, which are connected by venous links extending
PLATE 52.

Figure 1.

The second phalangeal joint of the middle finger of the left hand laid open by an oval incision, as for the anterior
flap of an amputation at this joint, to show the relations of the bone surfaces and the adjacent vessels,

1, The condyloid surface of the third or proximal phalanx | 3, The glenoid surface of the head of the second phalanx

of the middle finger. of the middle finger. : :
2. The external lateral digital artery. 4, The internal lateral digital artery.
Figure 2.

The metacarpo-phalangeal joint of the middle finger of the left hand opened, as in the first stage of an amputation
(by the lateral-flap method) of the finger, to show the appearance of the ends of the bones at this joint. The position
of the joint, on the dorsal surface, before the incisions were made, can be judged by comparison with the adjacent
fingers.

1. The head of the metacarpal bone of the middle finger. 4, The trochlear surface of the third, or proximal, phalanx
2. The external lateral digital artery. of the middle finger.
3. The middle finger retained to show the character of the | 5. The internal lateral digital artery.

incisions for its removal by the lateral-flap method.

Figure 3.

Amputation at the carpo-metacarpal joint of the thumb of the left hand (by the flap method), showing the relative
positions of the structures severed in the operation.

1. The radial artery where it passes into the palm. 5. The external dorsal artery of the thumb.
2, The os trapezium. 6. The radialis indicis artery.
3. The head of the metacarpal bone of the thumb drawn | 7. The princeps pollicis artery.

outward after division of the ligaments. : 8. The internal dorsal artery of the thumb.

4, The thumb retained to show the proper character of the
incisions in this amputation. ,

Figure 4.

The wrist-joint of the right hand laid open by an oval incision, as for the dorsal flap, in amputation at this joint,
showing especially the appearance of the articulation between the lower end of the radius and the semilunar and
scaphoid bones.

1. The lower end of the radius, showing the depression for 4. The cut tendons of the common extensor muscle to the

the semilunar and scaphoid bones. fingers.
2. The triangular fibro-cartilage between the lower end of | 5. The divided radial artery.
the ulna and the carpus. 6. The scaphoid bone.
8, The semilunar bone. 7. The cut extensor tendons to the thumb.
8. The cut extensor tendon to the index finger.

Figure 5.

Vertical section through the articulations at the wrist of the right hand to show the synovial membranes and the
cancellous structure and arrangement of the carpal bones.

1. The interosseous membrane. 9. Section through the unciform bone.

2. Section through the lower end of the ulna. 10. Section through the lower end of the radius.

3. The triangular inter-articular fibro-cartilage. 11, Section through the semilunar bone.

4, Section through the proximal row of the carpal bones. 12. Section through the scaphoid bone.

5. Section through the distal row of the carpal bones. 18. Section through the os magnum.

6. Section through the heads of the metacarpal bones. 14. Section through the os trapezium.

7. Section through the cuneiform bone. 15. Section through the trapezoid bone.

8. Section through the pisiform bone. 16. Section through the heads of the metacarpal bones.
Figure 6.

The left elhow-joint laid open posteriorly, as in the process of resection or excision of this articulation, to show the
relations of the opposing bones and the adjacent structures.

1. The lower posterior portion of the left arm. 6. The upper portion of the left forearm.
2. The severed tendon of the triceps muscle. 7. The ulnar nerve.

3. The trochlear surface of the lower end of the humerus. 8. The olecranon process of the ulna.

4, The head of the radius. 9, Branch of the recurrent ulnar artery.
5. Branch of the recurrent radial artery.
 

 

[ TOA
THE REGION OF THE FOREARM. 391

across the artery at frequent intervals, and join the vene comites of the
brachial artery in the ante-cubital fossa. The radial nerve, which is a
branch of the musculo-spiral nerve (page 360), is in relation to the outer
side of the radial artery in the middle third of the forearm only. About
six centimetres, or two and a half inches, above the wrist the radial nerve
passes under the tendon of the supinator longus muscle, to be distributed
to the back of the hand (Plate 47, Fig. 1, No. 16).

Above the wrist, in the pulse-area, the radial vessels are often tortuous
(Plate 46, Figs. 1 and 2). The line of reference for the radial artery
may be drawn from the middle of the bend of the elbow to the ulnar
side of the styloid process of the radius, or, for all practical purposes, an
incision made parallel to the radial border of the forearm and two centi-
metres, or a finger’s breadth, from it will expose the sheath of the radial
vessels.

The ulnar artery is larger than the radial, with which it commences
opposite the head of the radius at the bifurcation of the brachial artery.
In the first part of its course it cwrves deeply beneath the pronator teres,
the superficial flexor muscles, and the median nerve to the space between
the flexor sublimis digitorum and flexor carpi ulnaris muscles, being over-
lapped by the tendon of the latter, and so completely ensheathed by a re-
flection of the deep fascia that its pulsation above the wrist can rarely be
felt during life. Its course along the lower half of. the forearm is more
superficial and direct (Plate 46, Fig. 2).

The branches of the ulnar artery in the forearm are the anterior and
posterior ulnar recurrent, articular, common interosseous, muscular, and
carpal. The anterior and posterior ulnar recurrent arteries arise gener-
ally by a common trunk just after the origin of the main vessel at the
elbow. The anterior passes upward to anastomose with the anastomotica
magna and inferior profunda arteries. The posterior is the larger, and
ascends between the two heads of the flexor carpi ulnaris muscle to the
space between the olecranon and the internal epicondyle, by the side of
the ulnar nerve, to communicate with the inferior profunda, anastomotica
magna, and other arteries in the rete olecrani (page 370). The articular
branch pierces the anterior part of the capsule of the elbow-joint at the
392 THE REGION OF THE FOREARM.

outer border of the brachialis anticus muscle. The common «nterosseous
artery, which is four centimetres, or about one and a half inches, in
length, arises from the ulnar artery, below the bicipital tubercle of the
radius, and divides at the opening between the oblique and interosseous
ligaments (page 375) into anterior and posterior branches. The anierior
interosseous artery passes downward, being held in close contact with the
interosseous ligament by a sheath of areolar tissue, as far as the upper
border of the pronator quadratus muscle, where it subdivides into anterior
and posterior branches, which join respectively the anterior and posterior
carpal rete. The anterior interosseous artery in its course gives off the
nutrient arteries to the radius and ulna, supplies the adjacent muscles
with blood, and sends some perforating twigs through the interosseous
membrane to the deep extensor muscles. It is provided with two vene
comites (Plate 46, Fig. 2, No. 14), and accompanied by a branch of the
median nerve, the interosseous nerve, which overlies it superficially. The
posterior interosseous artery, after reaching the posterior surface of the
interosseous ligament, is in close relation with the posterior interosseous
nerve (page 394). It gives off, besides muscular twigs to the superficial
and deep extensor muscles, a recurrent branch, which joins the rete olecrani
above, and finally ends below in the posterior carpal rete. The muscular
branches of the ulnar artery are about a dozen in number, distributed to
the contiguous muscles upon the ulnar side of the forearm. The anterior
and posterior carpal branches arise from the ulnar artery above the wrist
and join with the corresponding branches from the radial artery in forming
the posterior carpal rete and the posterior palmar arch. The ulnar artery
is also closely ensheathed with its two venew comites, which are connected
at intervals by venous links and empty into the vene comites of the
brachial artery -below the elbow. The ulnar nerve takes a direct course
along the ulnar side of the forearm, from the internal epicondyle to
the radial side of the styloid process of the ulna, and therefore is at
a’ considerable distance from the upper part of the ulnar artery, but
for about six centimetres, or two and a half inches, above the wrist it
is in close relation to the sheath of the vessels, the nerve being always
to the ulnar side. Both vessels and nerve pass over the anterior an-
THE REGION OF THEH FOREARM. 393

nular ligament together (Plate 48), and are held closely to the pisiform
bone by an expansion of the fascia from the tendons of the flexor carpi
ulnaris muscle. The lines of reference for the ulnar artery may be drawn
from the tendon of the biceps at the front of the elbow to the middle of
the ulnar side of the forearm, and thence straight to the radial side of
the pisiform bone. Below the middle of the forearm the artery may be
exposed by an incision made parallel to the ulnar border two centimetres,
or a finger’s breadth, from it. It should not be forgotten that the ulnar
artery above the wrist is closely embraced by the border of the flexor
carpi ulnaris muscle, and that therefore it is not so accessible or easy
of exposure for a ligature as is the radial.

The median nerve in the forearm descends, after passing between the
two heads of the pronator radii teres muscle below the flexure of the elbow
(page 369), along the middle of the forearm, between the flexor sublimis
and flexor profundus digitorum muscles. It is quite deep at first, but
gradually becomes more superficial where the flexor muscles become ten-
dinous, and at the wrist it passes beneath the anterior annular ligament
between the outer tendon of the flexor sublimis and the inner border of
the flexor carpi radialis muscle (Plate 46, Fig. 1, No. 16, and Plate 48,
Fig. 3, No. 2). Near the elbow the median nerve sends, besides the two
branches to the two heads of the pronator teres muscle, muscular branches
to all the flexor muscles except the flexor carpi ulnaris and the ulnar
part of the flexor profundus. The anterior interosseous nerve leaves the
median just below the pronator teres muscle, and accompanies the ante-
rior interosseous vessels (page 392), being on their radial side. It supplies
the flexor longus pollicis, part of the flexor profundus, and the pronator
quadratus muscles. There is also a cutaneous palmar branch, arising five
centimetres, or two inches, above the wrist, which passes over the annular
ligament and supplies the skin of the palm. Very often there is a branch
from the median which joins the ulnar nerve where it is in more particular
relation to the ulnar artery. The ulnar nerve in the forearm, as already
stated (page 392), passes in a direct line from the front of the internal
epicondyle to the radial side of the pisiform bone. At the elbow it gives

off an articular branch to the elbow-joint, and soon after branches to both
50
394 THE REGION OF THE FOREARM.

of the heads of the flexor carpi ulnaris and the contiguous part of the
flexor profundus muscle. About the lower third of the forearm the ulnar
nerve distributes two branches, called from their distribution the anterior
and posterior ulnar cutaneous branches. The anterior passes superficially
over the ulnar artery to supply the skin of the front of the wrist, and
the posterior passes beneath the tendon of the flexor carpi ulnaris to the
dorsal surface. A few twigs from the ulnar nerve also supply the wrist-
joint.

The branches of the musculo-spiral nerve in the forearm, besides the
twigs supplied to the supinator longus and extensor carpi radialis longus
muscles (page 860), which leave the nerve in the space between the
brachialis anticus and the supinator longus in the outer depression of
the elbow, are the posterior interosseous and the radial. The posterior
interosseous nerve is the larger of the two terminal branches. It turns
backward through the supinator brevis and passes downward between the
superficial and deep extensor muscles to the middle of the posterior part of
the forearm, curving thence under the extensor secundi internodii pollicis
muscle to the back of the wrist. It supplies all the extensor muscles
with which it is in relation throughout its course; and may be regarded
exclusively as a motor nerve. The radial nerve is the cutaneous branch
of the musculo-spiral in the forearm. Its course is along the middle of °
the forearm, under cover of the supinator longus muscle and to the outer
side of the radial vessels. Above, in relation to the elbow, the nerve
is placed considerably to the outer side of the artery; below, it passes
beneath the tendon of the supinator longus muscle (Plate 47, Fig. 3,
No. 8), pierces the deep fascia, and subdivides into two terminal branches,
which are distributed to the skin on the back of the radial border of the
hand (page 408), some of the filaments communicating with the terminal
filaments of the musculo-cutaneous nerve.

Although fractures of the bones of the forearm are very common, it is
surprising how little attention has been given to the anatomy of the parts
‘involved, a knowledge of which would certainly influence the method of
their treatment. These injuries may affect both the radius and the ulna,
or either of these bones. When the two bones are broken, the violence
THE REGION OF THE FOREARM. 395

may be direct or indirect. When the radius is broken alone, it is generally
due to indirect violence transmitted from the hand. When the ulna is
broken alone, it is usually owing to direct violence and to its exposed posi-
tion. Whatever shortening or displacement may occur in any form of
these injuries is not so much in consequence of muscular action upon the
fragments as on account of the direction from which the violence is
received. The essential feature of the treatment of fractures of the fore-
arm is the preservation of the normal dimension of the interosseous space,
as already stated (page 376). This is generally appreciated nowadays;
but it is of equal importance to remember that in all fractures, in what-
ever region they occur, the bones are not the only tissues which suffer from
the injury. There is always accompanying the breach in the continuity
of the bones more or less damage to the soft structures about them.
The interosseous ligament and periosteum, with their special vessels, must
be lacerated, and although in one sense this is essential for the process
of repair, yet it presents a factor which probably accounts for the frequent
unsatisfactory results of treatment. It should be borne in mind that the
radius supports the hand, and that therefore it is most liable to suffer
from non-union. The superficial veins (page 408) play a valuable part
in nature’s efforts at repair, and should not be interfered with. As soon
as bony union has been obtained, passive motion should be resorted to at
regular intervals.

The fracture at the lower end of the radius, known as Colles’s fracture,
usually occurs transversely from half an inch to one and a half inches
above the wrist-joint. This is probably due to the character of the
internal structure of the bone in this situation. The expanded lower end
of the radius is mostly cancellous, while the shaft which joins it possesses
a greater amount of compact tissue (Plate 52, Fig. 5). This fracture is
usually caused by the weight being transmitted through the hand out-
stretched in the position of pronation to break the shock in the act of
falling. The degree of displacement depends measurably upon whether
the ligaments of the inferior radio-ulnar joint are ruptured.

The development of the radius occurs from three centres. The head
is ossified in the fifth year, and joins the shaft about the eighteenth year,
396 THE REGION OF THE WRIST AND THE HAND,

The lower extremity is ossified during the second year, but does not unite
with the shaft before the twentieth year. The development of the ulna also
is from three centres, one for the shaft and one for each end. At birth the
extremities are entirely cartilaginous. The olecranon does not begin to
ossify until the tenth year, and it is joined to the shaft about the sixteenth
year. The lower extremity ossifies in the fourth year, and joins the shaft
in the twentieth year. It should be noted that the epiphyses which meet
at the elbow unite with their shafts earlier than those at the opposite ends
of the bones, also that the foramina of the medullary arteries are directed
toward the elbow.

In amputation through the middle of the forearm by the antero-
posterior oval-flap method, the parts exposed in the flaps when made upon
the left side bear the following relations (Plate 51, Fig. 3). The anterior
flap is composed chiefly of the flexor muscles, in the margin of which in
the superficial fascia is the cut superficial median vein (No. 1). The
median nerve (No. 3) is in the middle of the flap, between the severed
superficial and deep flexor muscles. The ulnar vessels and the ulnar
nerve (No. 5) are close to the sawn end of the ulna, and the radial
vessel and the radial nerve are close to the sawn end of the radius.
The interosseous vessels and nerve are between the bones. The posterior
flap is composed chiefly of the extensor muscles, and in its margin will
be found the superficial radial vein (No. 10).

THE REGION OF THE WRIST AND THE HAND.

The skeleton of the hand consists of the carpus, or wrist, which
connects the hand with the forearm, the metacarpus, or median portion
of the hand, and the phalanges, or digital extremities. The carpal bones
are eight in number, polygonal in shape, and are composed of cancellous
tissue enclosed in a compact layer. They are arranged in two rows, each
of which contains four bones, counting from the external or radial side, as
follows: in the upper or proximal row, the scaphoid, semilunar, cunei-
form, and pisiform; in the lower or distal row, the trapezium, trapezoid,
magnum, and unciform. ach of these little bones presents a dorsal
surface which is usually comparatively smoother and larger than the
THE REGION OF THE WRIST AND THE HAND. 397

palmar surface, which is rough for the attachment of the ligaments, while
the lateral borders are covered, in the recent state, with articular cartilage.
When they are collectively united they form an arch with its concavity
toward the palm, the scaphoid and the trapezium, the two outer bones of
the two rows, and the pisiform and the unciform, the two inner bones
of the two rows, projecting laterally. The contiguous surfaces of the
carpal bones are so adapted that they form with one another gliding joints,
the motion between any two of them being very slight, and limited to ex-
tension and flexion, with the exception of the os magnum, which appears
to be also capable of a very little rotation. The articulation between the
two rows, the intercarpal joint, however, admits of considerable motion,
and materially contributes to the flexion and extension of the hand.
The three principal bones of the upper row, the scaphoid, semilunar,
and cuneiform, are connected by interosseous ligaments at their margins
so that they present a convex surface which is received into the con-
cavity formed by the articular surface of the lower end of the radius
and the under surface of the triangular fibro-cartilage, thus establishing
the important radio-carpal or wrist joint (Plate 52, Fig. 5).

The triangular fibro-cartilage separates the inferior radio-ulnar joint
(page 375) from the wrist. It extends transversely beneath the lower
end of the ulna, being attached by its apex to the groove between the
styloid ‘process and the head of the ulna, and by its base to the ridge
between the ulnar depression and the articular surface of the lower ex-
tremity of the radius. Its lower surface is therefore really a continuation
inward of the radial articular surface. The synovial membrane lining the
cavity of the wrist-joint is separated from the synovial pouches between the
carpal bones by the interposition of the interosseous ligaments, but there
is very often a communication between the synovial cavities of the inferior
radio-ulnar and radio-carpal joints through a deficiency in the triangular
fibro-cartilage. The flexor and extensor tendons as they pass over this
region afford strong protection to it, but beneath them there are fibrous
bands which extend mostly from the margins of the radius and fibro-
cartilage to the first row of carpal bones, and which with the intervening
connective tissue constitute the capsular ligament of the wrist. The
398 THE REGION OF THE WRIST AND THE HAND.

various bands which have been specialized are the anterior ligament (or
ligamentum arcuatum), composed mainly of intersecting fibres which pass
obliquely from the anterior lip of the radius to the palmar surface of
the scaphoid, semilunar, and cuneiform bones, a few fibres being inserted
also into the os magnum. ‘This is reinforced by an additional band. placed
more superficially, extending from the base of the styloid process of the
ulna to the cuneiform bone, and attached to the fibro-cartilage between
them; the external lateral ligament, which is short and thick and extends
from the styloid process of the radius to the outer side of the scaphoid ;
the posterior ligament (or ligamentum rectum), consisting of intersecting
fibres which pass from the posterior margin of the radius and the fibro-
cartilage to the dorsal surface of the semilunar and cuneiform bones; and
the internal lateral ligament, which is a round band, longer and narrower
than the external,'and extends from the tip of the styloid process of the
ulna to the cuneiform bone.

The movements permitted at the wrist-joint are flexion, extension,
abduction, adduction, and circumduction, but not rotation. This joint
acts harmoniousiy with the intercarpal and carpo-metacarpal joints, all of
them being closely associated, so that they move simultaneously. The
radio-carpal joint is supplied by filaments from the ulnar and posterior
interosseous nerves. In opening the wrist-joint from the dorsal surface, as
in amputation (Plate 52, Fig. 4), the peculiar convex arrangement of the
upper row of carpal bones and the cup-shaped concave surface formed
by the lower end of the radius and triangular cartilage present themselves,
together with several bands of the capsule which project across the cavity
of the joint and about which the synovial membrane is gathered into folds.

The pisiform bone articulates with the cuneiform bone, and the joint
thus formed is surrounded by a capsular ligament and provided with a
distinct synovial membrane. It is also strongly connected by ligamentous
fibres with the unciform and fifth metacarpal bones. It serves mainly
to give attachment to the flexor carpi ulnaris and abductor minimi digiti
muscles. Besides the synovial membranes peculiar to the inferior radio-
ulnar joint, to the radio-carpal or wrist joint, and to the piso-cuneiform
joint, just described, there are two distinct synovial membranes, enclosed
THE REGION OF THE WRIST. AND THE HAND. 399

within the articulations formed by the carpal bones in relation to one
another (the intercarpal joint) and to the bases of the metacarpal bones.
The largest of these extends between both rows of the carpal bones,
sending short pouches upward between the bones of the first row, and
longer pouches downward between the bones of the second row, which are
expanded between the latter and the bases of the contiguous metacarpal
bones. The smaller synovial membrane is interposed between the trape-
zium and the metacarpal bone of the thumb. It is not uncommon to find
that the interosseous ligament between the magnum and unciform bones is
attached to the ridge on the fourth metacarpal bone, and consequently there
is a subdivision of the larger synovial membrane between the unciform and
the bases of the fourth and fifth metacarpal bones. The carpal bones are
all connected by interosseous ligaments at their dorsal and palmar margins,
of variable development, which blend with the especial ligaments of the
intercarpal jownt, and are called, from their positions, the palmar and dorsal
ligaments. The palmar consists of strong fibres which radiate from the
tuberosity of the os magnum to all the adjacent bones, and therefore is
sometimes known as the ligamentum radiatum. The dorsal is somewhat
weaker, and consists mostly of transverse fibres which extend from the
back of the os magnum over the other bones and unite with the dorsal
ligaments of the radio-carpal joint above and the carpo-metacarpal joints
below.

The metacarpal bones, five in number, are modified long bones,
each consisting of a somewhat triangular shaft, slightly bowed, with the
concavity toward the palm. The proximal ends, or bases, are irregular,
presenting tuberosities for the attachment of the ligaments and smooth
facets for articulation with the carpal bones and the adjoining metacarpal
bones, with which they are in relation. The distal ends, or heads, are
quadrate, and provided with lateral depressions for ligaments, and sphe-
roidal eminences for reception upon the glenoid surfaces of the proximal
ends of the first phalanges. The articular processes of the heads embrace
more of the palmar than of the dorsal surfaces. The metacarpal bones
of the fingers are proportionately more slender than the metacarpal bone
of the thumb, which is shorter and broader. ‘They all diverge slightly
PLATE 568.
Figure 1.

Topographical survey of the right side of the head, face, and neck, with especial adaptation to cranio-cerebral study.
the localization of the areas of distribution of the sensory nerves, and spots where electrical stimulation produces reflex

contractions of some of the muscles in these regions.

laryngotomy.

1, Cutaneous area of supra-orbital
nerve.

2. Position of superior frontal fissure,

8. Cutaneous area of auriculo-tem-
poral nerve.

4, Position of the fissure of Rolando,

5. Position of horizontal branch of
the fissure of Sylvius.

6. Spot where reflex contraction of
the temporal muscle may be
produced.

7. Cutaneous area of occipitalis major
nerve.

8, Cutaneous area of occipitalis mi-
nor nerve.

9. Spot where reflex contraction of
the splenius muscle may be
produced.

10. Spot where reflex contraction of
the trapezius muscle may be
produced.

11, Posterior cervical folds of the in-

 

tegument produced by contrac-
tion of the trapezius muscle.

12. Spot indicating position of the
brachial plexus of nerves.

13, Cutaneous area of supra-trochlear
nerve,

14. Position of inferior frontal fissure.

15, Cutaneous area of infra-trochlear
nerve.

16. Cutaneous area of lachrymal nerve.

17, Cutaneous area of nasal nerve.

18, Position of ascending branch of

_ the fissure of Sylvius.

19, Cutaneous area of infra-orbital
nerve.

20, Cutaneous area of temporo-malar
branch of the superior maxil-
lary nerve.

21, Spot where. reflex contraction of
the masseter muscle may be
produced.

22, Cutaneous area of buccal nerve.

Figure 2.

 

Also the landmarks for the operations of tracheotomy and of

23. Cutaneous area of mental nerve.

24, Position where facial artery and
vein pass over the body of the
jaw in front of masseter muscle.

25. Spot where reflex contraction of
the sterno-cleido-mastoid mus-
cle may be produced.

26, Position of body of the hyoid bone.

27, Cutaneous area of auricularis mag-
nus nerve.

28, Anterior prominence of the thy-

roid cartilage.

Point where the common carotid
artery is in relation to the trans-
verse process of the fourth cer-
vical vertebra.

30. Position of the hoop of the cricoid

cartilage.

81. Spot where reflex contraction of
the omo-hyoid muscle may be
produced.

82, Supra-sternal notch.

2!

so

The left hand in the position of pronation, showing a topographical survey of the areas of distribution of the sensory
nerves on the back of the hand and fingers, and spots where electrical stimulation produces reflex contraction of some

of the muscles.

1, Area supplied by the median nerve
on ulnar side of dorsal surface
over third phalanx of middle
finger.

2. Lowest distribution of ulnar nerve
on ulnar side of middle finger.

8. Area supplied by median nerve on
dorsal surface of radial side over
third phalanx of ring finger.

4. Lowest distribution of ulnar nerve
on ulnar side of dorsal surface
of ring finger.

5, Ulnar nerve on radial side of little
finger.

6. Ulnar nerve on ulnar side of little
finger.

7. Spot where contraction of the third

 

dorsal interosseous muscle may
be produced.

8. Spot where contraction of the
fourth dorsal interosseous mus-
cle may be produced.

9, Spot where reflex contraction of
the abductor minimi digiti mus-
ele may be produced.

10. Ulnar nerve on back of wrist.

11, Median nerve on dorsal surface of
third phalanx of middle finger.

12. Lowest distribution of radial nerve
on radial side of middle finger.

13, Median nerve on dorsal surface of
ulnar side of third phalanx of
index finger.

14, Lowest distribution of radial nerve
on ulnar side of index finger.

Figure 8.

 

15. Median nerve on radial side of dor-
sal surface of third phalanx of
index finger.

16. Lowest distribution of radial nerve
on radial side of index finger.

17, Radial nerve on dorsal surface of
thumb.

18. Spot where contraction of second
dorsal interosseous muscle may
be produced.

19, Spot where contraction of first dor-
sal interosseous muscle may be
produced.

20, Radial nerve on dorsal surface of

wrist.

. Lowest distribution of musculo-

spiral nerve.

i
eS

The right hand in the position of supination, showing a topographical survey of the areas of distribution of the sensory
nerves on the palm of the hand and anterior surface of the fingers, and spots where some of the muscles may be caused to
contract by electrical stimulation. Also the surface-markings on the palm of the hand in relation to the arterial arches.

1, Median nerve on ulnar side of pal-

mar surface of middle finger.

2. Median nerve on radial side of

palmar surface of ring finger.

3. Ulnar nerve on ulnar side of pal-
mar surface of ring finger.

4, Ulnar nerve on palmar surface of

radial side of little finger.

5. Ulnar nerve on palmar surface of
ulnar side of little finger.

Linea mensalis.

Spot where contraction of the
third lumbrical muscle may be
produced.

. Spot where contraction of the
fourth lumbrical muscle may be
produced.

9. Linea hepatica.

10. Linea cephatica.

11. Spot where contraction of the op-
ponens minimi digiti muscle
may be produced.

12. Spot where contraction of the

pa)

oOo

 

abductor minimi digiti muscle
may be produced.

13. Spot where contraction of the
opponens pollicis muscle may
be produced.

14. Spot where contraction of the
palmaris brevis muscle may be
produced.

15, Ulnar nerve on front of wrist.

16. Median nerve on palmar surface of
radial side of middle finger.

17. Median nerve on palmar surface of
ulnar side of index finger.

18. Median nerve on palmar surface of

__ radial side of index finger.

19. Spot where contraction of the sec-
ond lumbrical muscle may be
produced.

. Spot where contraction of first lum-
brical muscle may be produced.

21. Spot where contraction of the
adductor pollicis muscle may be
produced.

y
S

 

22. Internal branch of median nerve
on palmar surface of thumb.

23. External branch of median nerve
on palmar surface of thumb.

24, Spot where contraction of the flexor
brevis pollicis muscle may be
produced.

25, Linea vitalis.

26. Spot where contraction of the
abductor pollicis muscle may be
produced.

27. Median nerve below the wrist.

28, Linea transversa carpi.

29. Median nerve above the wrist.

30. Spot where contraction of the flex-
or longus pollicis muscle may be
produced.

31. Spot where contraction of the
tendons of index and little fin-
gers may be produced.

32. Spot where contraction of the ten-
dons of middle and ring fingers
may be produced.
Von i
22

 

 

         

LELLAN, MD.

COLL

yrisht(82/ by Georse™

nw

late 53

Armstrong & Co Lith Boston

tographed and Designed trom Nature by Georoe Mc.Crettan M.D
THE REGION OF THE WRIST AND THE HAND. 401

from the carpus, but that of the thumb diverges more than the others.
The metacarpal bone of the index finger is the longest of the series, the
rest of which are successively shorter toward the little finger, its meta-
carpal bone being longer than that of the thumb. The latter is peculiar
in having its palmar surface turned toward. the ulnar side of the hand;
its base has no lateral facet, being provided with an oval facet for articu-
lation with the trapezium only. The head is less pronounced than in the
corresponding bones, and has two marked processes on the palmar surface
for the two sesamoid bones (page 402). The joint between the trapezium
and the metacarpal bone of the thumb is distinct and protected by a cap-
sular ligament, which is particularly strong in the external and dorsal
portions. The proximal ends of the metacarpal bones are connected by
interosseous ligaments, and each carpo-metacarpal joint is provided with
palmar, dorsal, and lateral ligaments.

The phalanges are fourteen in number,—three in each finger and two
in the thumb. They are designated as the first or proximal, the second or
medial, and the third or distal. The latter are also called the ungual
phalanges, because they support the nails. The phalanges in each of the
digital extremities successively decrease in size toward the wrist. They
are all long bones with semi-cylindrical shafts. The dorsal surfaces of the
first and second phalanges are slightly convex, except that of the thumb,
which is rather concave and tapers toward the distal end. The upper
ends of the first phalanges are severally provided with glenoid depressions
variably modified for articulation with the metacarpal bones to which they
belong, and their lower ends present trochlear surfaces for articulation with
their proper second phalanges. The upper ends of the latter have each a
double concavity for the reception of the trochlear surfaces of the first |
phalanges, and their lower ends are also provided with similar trochlear
surfaces, but smaller than those of the first phalanges. The second
phalanges of the middle and ring fingers are about equal in length, that
of the index finger is shorter, and that of the little finger is the smallest
of the series.

The third or ungual phalanges are all provided with concavities at

their upper ends, each presenting two depressions, for articulation with the
61
402 THE REGION OF THE WRIST AND THE HAND.

second phalanges, and they terminate in the horseshoe-shaped ungual
processes, which are roughened on their palmar surfaces for the attach-
ment of the pulps of the fingers. The ungual process of the thumb is
the largest and broadest, while the ungual processes of the middle, ring,
index, and little fingers follow in order as named.

The metacarpo-phalangeal joints are enarthrodial, being capable of
extension, flexion, abduction, adduction, and slight rotation. The con-
tiguous bony surfaces are each provided with a layer of articular cartilage
and a synovial membrane, the glenoid depressions on the proximal ends
of the first phalanges being deepened by small glenoid ligaments. These
joints are surrounded by capsular ligaments, which being comparatively
weak in their dorsal portions are strengthened by expansions from the
extensor tendons (Plate 49). The fibres at each side are very strong,
and have been specialized as lateral ligaments.

The second and third interphalangeal joints are ginglymoid, being
capable only of flexion and extension. They are constructed similarly to
the metacarpo-phalangeal joints, having glenoid and capsular ligaments,
the side bands of the latter being strengthened into lateral ligaments. At
the metacarpo-phalangeal joint of the thumb there are always found two
sesamoid bones, the outer being the larger. They are the ossified nodules
of fibro-cartilage, in relation to the lateral ligaments, and receive the inser-
tions of short muscles.

The spaces between the metacarpal bones are occupied by the inter-
osseous muscles, which are arranged in two sets, palmar and dorsal. There
are three palmar interosseous muscles,.each of which has a single origin.
The first arises from the base and front of the metacarpal bone of the
index finger, and is inserted into the ulnar side of the dorsal aponeurosis
of the three phalanges belonging to the digital extremity of that finger.
The second arises from the metacarpal bone of the ring finger, and is in-
serted into the radial side of the dorsal aponeurosis of the corresponding
phalanges. The third arises from the metacarpal bone of the little
finger, and is inserted into the radial side of its phalanges. There are
four.dorsal interosseous muscles, each of which has two origins. The first
arises from the ulnar side of the upper portion of the metacarpal ‘bone
THE REGION OF THE WRIST AND THE HAND. 403

of the thumb and the whole of the adjacent side of the metacarpal
bone of the index finger, and is inserted into the radial side of the
base of the proximal phalanx and the dorsal aponeurosis over the
medial and distal phalanges of that finger. The second arises from the
adjacent sides of the metacarpal bones of the index and middle fingers,
and is inserted into the radial side of the aponeurosis enveloping the
phalanges of the middle finger (Plate 49, Fig. 1, No. 19). The third
arises from the adjacent sides of the metacarpal bones of the middle and
ring fingers, and is inserted into the ulnar side of the aponeurosis over
the phalanges of the middle finger. The fourth arises from the adja-
cent sides of the metacarpal bones of the ring and little fingers, and is
inserted into the ulnar side of the aponeurosis over the phalanges of
the ring finger. The general function of the palmar set is to adduct
the fingers toward the middle line of the middle finger, while that of
the dorsal set is to abduct the fingers from that line.

The dorsal aponeurosis of the fingers, above mentioned, is formed by
the expansion of the extensor tendons (Plate 49) after they have given off
the flat bands to the sides of the metacarpo-phalangeal joints. It is con-
tinued down the fingers, being attached by a middle slip to the bases
of the medial phalanges, and by lateral slips which intersect and are
inserted into the bases of the ungual phalanges (page 402). On the sides
of the proximal phalanges the aponeurosis receives the insertions of the
interosseous muscles, described above, as well as those of the dwmbricales
muscles. The latter are four slender bundles of muscular fibres which
arise from the deep flexor tendons in the palm of the hand. The jirst
and second are attached to the radial sides of the tendons of the index
and middle fingers, and are inserted into the radial sides of the digital
aponeuroses below. The ¢hird and fourth arise from the contiguous surfaces
of the adjacent tendons of the ring and little fingers, and are inserted
into the radial sides of their digital aponeuroses. The first and second
lumbricales are supplied by the median nerve, the third and fourth by
the ulnar nerve. Their function is to flex the metacarpo-phalangeal joints,
but they can also assist the action of the extensor tendons in maintaining
the extension of the interphalangeal joints. It has already been stated
404 THE REGION OF THE WRIST AND THE HAND.

that all the flexor tendons become enclosed in aponeurotic sheaths opposite
the palmar surface of the metacarpo-phalangeal joints, and that as they
enter these sheaths the superficial tendons divide into lateral slips, which
diverge about the middle of the proximal phalanges, to allow the deep
flexor tendons to pass between them. The two lateral slips of the super-
ficial tendons blend together behind the deep tendons, and then separate
again, to be finally inserted into the sides of the medial phalanges, while
the deep tendons are continued on, to be inserted into the bases of the
ungual phalanges. In this connection it should be noted that the meta-
carpo-phalangeal joints are capable of being flexed so that the fingers may
be brought into the hollow of the palm, thus forming the jist, while the
heads of the metacarpal bones and the bases of the proximal phalanges
are made prominent at the knuckles. The fingers can be extended only
very little beyond the plane of the metacarpus, but they can be readily
moved laterally. The interphalangeal joints can be flexed or extended so
that the separate phalanges shall move in the same manner as the entire
fingers, but they have no lateral movement.

The construction of the joint of the ¢humd, between its metacarpal
bone and the trapezium, enables it to be opposed to all the fingers. The
special flexor (page 383) and extensor (page 388) muscles of the thumb
have already been described. Besides these there are the muscles which
constitute the ball of the thumb.

The abductor pollicis muscle (Plate 48, Fig. 3, No. 3) arises from the
anterior annular ligament and the tubercle of the trapezium, and is inserted
into the outer side of the proximal phalanx of the thumb. This muscle
is supplied by a branch of the median nerve, and often consists of two
slips, between which passes the superficialis vole artery (page 389). The
action of this muscle is to draw the thumb away from the rest of the hand.

The opponens pollicis muscle (Plate 48, Fig. 4, No. 2) arises beneath
the abductor, also from the annular ligament and the trapezium, and is
inserted into the metacarpal bone of the thumb upon the whole length of
its radial border. It is supplied by a branch of the median nerve. By
its action the thumb is brought forcibly in apposition with all the fingers.

The flecor brevis pollicis muscle has a double origin, a superficial portion
THE REGION OF THE WRIST AND THE HAND. 405

arising from the trapezium and annular ligament, which is inserted into
the outer sesamoid bone and the radial surface of the proximal phalanx
of the thumb, and a deeper portion which arises from the bases of the
metacarpal bones of the index and middle fingers and the fibrous arch
between them and the trapezoid and magnum and is inserted into the
inner sesamoid bone and the base of. the proximal phalanx of the thumb.
The superficial portion is supplied by the median nerve, the deep portion
by the ulnar nerve. The tendon of the Jong flexor muscle passes between
these two portions, to be inserted into the base of the ungual phalanx of
the thumb (page 383). The function of the flexor brevis is to flex the
proximal phalanx of the thumb upon the palm.

The adductor pollicis muscle (Plate 48, Fig. 4, No. 7) is triangular,
and arises from the shaft of the metacarpal bone of the middle finger,
its fibres blending with those of the deep portion of the flexor brevis, to
be inserted into the inner sesamoid bone and the adjoining part of the
proximal phalanx of the thumb. Sometimes two portions of this muscle
are differentiated as the oblique and transverse adductors, but they are
very imperfectly separable. The adductor pollicis is supplied by the ulnar
nerve. Its action is to augment that of the flexor brevis, and to enable
the tip of the thumb to be brought into contact with the tips of the
fingers. The mobility of the thumb and the power which it possesses
through its many muscles render it one of the distinguishing features
of the human hand.

The muscles of the ball of the little finger resemble somewhat those
of the thumb. The abductor minimi digiti muscle (Plate 48, Fig. 2, No.
18) arises from the pisiform bone and its capsular ligament and is inserted
into the ulnar side of the base of the proximal phalanx of the little finger,
blending with its dorsal aponeurosis. It sometimes receives an accessory
slip from the tendon of the flexor carpi ulnaris. The flexor brevis minimi
digiti muscle (Plate 48, Fig. 4, No. 17) is really a part of the abductor.
It arises from the unciform process, and is inserted also into the base of
the proximal phalanx of the little finger and into the adjacent aponeurotic
arch over the deep flexor tendon. ‘The action of the abductor muscle
is to draw the little finger away from the rest of the hand, and it is
406 THE REGION OF THE WRIST AND THE HAND.

assisted in this effort by the flexor brevis. The opponens minimi digits
muscle arises beneath the flexor brevis from the unciform process and
the under surface of the annular ligament, and is inserted on the ulnar
side of the metacarpal bone of the little finger. The action of this muscle
is to draw the metacarpal bone of the little finger upon the palm, so as to
strengthen its power of grasping. All these muscles of the little finger
are supplied with branches from the ulnar nerve.

The surface-markings of the wrist and hand are of considerable topo-
graphical importance. The positions of all the bony prominences in this
region should be noticed, in extension and flexion, as well as in supination
and pronation. The lower extremities of the radius and ulna can be
readily defined, because they are to a great extent superficial. It has
already been stated that the laxity of the capsular ligament about the
inferior radio-ulnar joint permits of slight lateral motion between the
bones of this articulation when the radius is rotated, and consequently:
it is the styloid process of the ulna which is felt in supination, and not
the head of that bone. The styloid process of the radius is placed more
anteriorly than the corresponding process of the ulna, and is also twelve
millimetres, or half an inch, lower. Below and in front of the radial
styloid process the tubercle of the scaphoid bone can be felt, and below
and in front of the ulnar styloid process is the pisiform bone. A line
drawn from one styloid process to the other will be found to pass down-
ward and outward, and its extremities represent the lower limits of the
radio-carpal joint, the line of the joint itself being in the form of an are
with the convexity upward (Plate 52, Fig. 4).

The skin over the wrist is quite loose, thin, and free from fat. In
front of the wrist the skin is closely connected with the deep fascia, and
is marked by transverse lines, of which the lowest is usually very distinct
(Plate 58, Fig. 3, No. 28). It is about one and a. half centimetres, or
three-quarters of an inch, below the wrist-joint, and crosses the os mag-
num in the line of the metacarpal bone of the middle finger. This line
also corresponds to the upper border of the anterior annular ligament (page
412). About the middle of the anterior surface of the wrist the tendon
of the palmaris longus muscle is usually plainly seen, especially when
THE REGION OF THE WRIST AND THE HAND. 407

the wrist is flexed with the fingers extended. The flexor carpi radialis
tendon is on its outer side. The median nerve as it descends from the
forearm to enter the palm beneath the annular ligament is between these
two tendons (Plate 48, Fig. 4, No. 1). The tendon of the flexor carpi
ulnaris muscle can be easily distinguished as it passes to the pisiform bone
on the inner side of the wrist, when that joint is slightly flexed and
the little finger closed upon the palm. The tendons of the flexor sublimis
digitorum muscle are in the depression between the tendons of the flexor
carpi ulnaris and the palmaris longus. Within the superficial fascia on
the palmar surface of the thumb and the front of the wrist the superfi-
cial veins can be seen through the thin skin passing upward from the
palmar plexus to empty into the median and ulnar veins. On the radial
border of the wrist the tendons of the extensor ossis metacarpi and primi
internodii pollicis muscles are brought into distinct relief when the thumb
is abducted; and on the back of the wrist the tendon of the extensor
secundi internodii pollicis muscle is rendered prominent when the thumb
is forcibly extended and abducted. The extensor carpi ulnaris tendon can
be felt upon the inner side of the posterior surface of the wrist, and to
the radial side of it are the tendons of the extensor communis digitorum.
If the skin is removed from the back of the hand, the above tendons
will be seen as they pass beneath the posterior annular ligament (Plate 49,
Fig. 8, No. 7). This consists of a special condensation of the deep fascia
in this locality, which is formed by the transverse fibres of the deep fascia
prolonged from the forearm and augmented by special fibres which are
attached to the ridges on the back of the lower end of the radius and
thence pass obliquely inward over the capsular ligament of the inferior
radio-ulnar joint to the ulnar side of the carpus, where they are attached
to the pisiform and cuneiform bones. The several attachments of the deep
fibres to the ridges on the radius convert the grooves into canals for the
passage of the extensor tendons. There are sia compartments thus formed
in the posterior annular ligament, as follows: one for the extensor ossis
metacarpi and the extensor primi internodii pollicis; one for the extensor
radialis longior and the extensor radialis brevior; one for the extensor
secundi internodii pollicis; one for the extensor indicis and the extensor
408 THE REGION OF THE WRIST AND THE HAND.

communis digitorum; one for the extensor minimi digiti; and one for the
extensor carpi ulnaris. All these compartments are lined by synovial mem-
branes which envelop the tendons and accompany them nearly as far as
their insertions. Sometimes there is a communication between one of the
above synovial sheaths and the cavity of the wrist-joint.

The skin over the back of the hand is very fine, and but loosely attached
to the annular ligament enclosing the tendons and to the deep fascia pro-
longed from it to the knuckles below, owing to the extreme laxity of the
subcutaneous tissue. This is manifest in cedema and extravasations which
often occur here. The skin is also provided with numerous short fine hairs
and sebaceous follicles. The hairs are so set that they have an inclina-
tion toward the ulnar border, and they are extended also over the dorsal
surfaces of the first and second phalanges of all the fingers. The sweat-
glands are not so numerous on the back of the hand as they are on the
pal, where they are remarkable for the profuseness of their perspiration
under certain conditions. The skin of the back of the hand is not very
sensitive to tactile impressions.

The superficial veins of the hand (Plate 47, Fig. 3) arise mainly from
the dorsal plexuses, which commence by radicles forming arches over the
backs of the proximal phalanges. On the ulnar side the ulnar dorsal
plexus is formed by the union of the vein from the little finger (the vena
salvatella) with the veins from the third and fourth interdigital clefts.
From this plexus usually two veins ascend to the forearm, a small anterior
superficial ulnar and a larger posterior superficial ulnar. On the radial
side the radial dorsal plexus is formed by the junction of the vein from
the thumb (the vena cephalica pollicis) with veins from the index and
middle fingers, which terminate in the radial veins above. There is much
diversity in the arrangement of these veins on the back of the hand, and
the two plexuses are frequently connected by a transverse venous link,
which presents an H-shaped appearance.

As the vein from the thumb passes upward it crosses the hollow formed
by the extensor tendons of the thumb, and in close relation with it are the
branches of the radial nerve (Plate 47, Fig. 38, No. 9) which pass to supply
the dorsal surface of the thumb and the dorsal surface of the index and
THE REGION OF THE WRIST AND THE HAND. 409

the radial side of the middle finger as far as their distal phalanges (Plate
53, Fig. 2). At the bottom of the hollow, beneath the tendons, the radial
artery, in a bed of fat which separates it from the scaphoid and trapezium,
passes (Plate 49, Fig. 1, No. 17) to the interval between the first and
second metacarpal bones to enter the palm between the two portions of
the abductor indicis muscle and form the deep palmar arch (page 415).
Before leaving the back of the hand the radial artery gives off the pos-
terior carpal artery, which passes beneath the extensor tendons, forming
an arch with the corresponding branch from the ulnar artery. From
this dorsal arch the dorsal interosseous arteries arise (Plate 47, Fig. 3,
and Plate 49, Fig. 3). They descend to the muscles occupying the
several interosseous spaces, supplying them and the other adjacent parts,
and inosculating near the metacarpo-phalangeal joints with the perfo-
rating branches from the deep palmar arch. On the ulnar side of
the back of the hand the wlnar nerve appears just below the styloid
process of the ulna, and in relation to the vein from the little finger
(Plate 47, Fig. 8, No. 5) it divides into branches which supply the
dorsal surface of the little finger, the whole of the dorsal surface of
the ring finger, except the radial border of the distal phalanx, and the
dorsal surface of the ulnar side of the middle finger, except over the
distal phalanx (Plate 53, Fig. 2, No. 10).

The palm of the hand presents some conspicuous features which
should be closely examined. There is a large prominence on the radial
side, formed by the muscles of the ball of the thumb, already described
(page 404), which is called the thenar eminence; while upon the ulnar
side the long prominence corresponding to the muscles of the ball of the
little finger is the Aypothenar eminence. The two eminences are some-
times named the heel of the hand. Between them, over the annular
ligament, there is a depression, which broadens toward the fingers, and
when the latter are flexed forms the hollow of the hand. The skin of the
palm is attached to the fascia beneath along the many lines of flexion,
three of which are especially marked and have been designated as follows.
The first line, curving round the base of the thenar eminence, is caused by

the constant flexion of the thumb, and is called the linea vitalis (Plate 53,
52
410 THE REGION OF THE. WRIST AND THE HAND.

Fig. 8, No. 25). It corresponds to the attachment of the radial margin of
the palmar fascia. The second line commences at the radial side of the
hand, between the index finger and the thumb, and extends across the palm
to about the middle of the metacarpal bone of the little finger, is caused
by the apposition of the middle and index fingers with the thumb, and is
known as the linea cephalica. This line indicates the position of the
metacarpo-phalangeal joint of the index finger, and is a useful guide in
its amputation. The third line, which is the lowest upon the extended
palm, commences at the elevation between the index and middle fingers
and runs obliquely to the ulnar border of the hand, is caused by the
flexion of the middle, ring, and little fingers, and is known as the linea
mensalis. ‘The last two lines are intersected by another, less conspicuous,
which takes a vertical course nearly over the metacarpal bone of the
middle finger, is called the linea hepatica, and gives to these markings
the characteristic outline of the letter M (Plate 53, Fig. 3). The second
line where it crosses the metacarpal bone of the ring finger is about over
the lowest part of the superficial palmar arch (page 414). The third line
is the most important. It is one centimetre, or a little less than half an
inch, above the metacarpo-phalangeal joints of the fingers which produce it,
and indicates very nearly the upper limits of the synovial sheaths of the:
index, middle, and ring fingers. Just beyond this line the palmar fascia
divides into its four slips (page 412). The position of the metacarpo-
phalangeal joints can be ascertained by alternate flexion and extension,
and will be found to be for each finger at a point midway between the
third palmar line and the webs of the fingers. ‘The same points refer
to the bifurcation of the digital arteries (Plate 48, Fig. 4). When the
proximal phalanges are extended and the medial and distal are flexed,
three little elevations are noticed, formed by the pressing forward of the
little cushions of fatty tissue which occupy the arches made by the digital
slips of the palmar fascia over the flexor tendons. The palmar surface
is further marked at the bases of the fingers by transverse flexion-folds,
which are single for the index and little fingers and double for the middle
and ring fingers. These folds are about two centimetres, or three-quarters
of an inch, below the corresponding metacarpo-phalangeal joints. There
THE REGION OF THE WRIST AND THE HAND. 411

are similar folds produced by the flexion of the interphalangeal joints,
the first of which is double and the second usually single for each finger.
They do not correspond to the joints, being usually from three to one
and a half millimetres, or from one-eighth to one-sixteenth of an inch,
above them. The thumb is provided with two folds corresponding to its
two joints, the upper one of which passes obliquely over the metacarpo-
phalangeal joint. The free margin of the web between the fingers is
called the plica interdigitalis, and is about two centimetres, or three-
quarters of an inch, from the metacarpo-phalangeal joints on the palmar
surface. These measurements are exact, but it is always best for prac-
tical purposes to remember the unfailing rule of exercising the functions
of these joints when in doubt, which will demonstrate their position
and features better than any description. The palmar epidermis varies
in thickness mainly according to the uses to which the hands are put.
There are abundant sweat-glands, as already stated. The papille are
exceedingly large and numerous, and contain touch-corpuscles. On the
rounded pulps of the fingers they are arranged in irregular concentric
ridges, never being precisely alike in any two hands.

The subcutaneous tissue of the palm is scanty, and resembles the same
tissue in the scalp, as mentioned in the description of that structure, as it is
intimately associated with the palmar fascia beneath. Owing to the dense-
ness of this tissue and the thickness of the cuticle, the hand is peculiarly
adapted to sustain the effects of pressure and friction. The ulnar border
of the palmar part of the hand is remarkably well provided in this respect
and protected by the soft parts, without the presence of any large nerves.
The palmaris brevis muscle consists of short transverse fibres arising from
the skin over the hypothenar eminence and attached to the palmar fascia.
Its contraction assists in grasping. When the skin of the palm with the
above muscle is carefully removed, the palmar fascia and the anterior an-
nular ligament are exposed.

The palmar fascia is a strong, silvery-white, glistening tissue spread
over the centre of the palm, and when completely developed is really the
expansion of the tendon of the palmaris longus muscle (Plate 48, Fig. 1,
No. 8). In such cases it overlies the annular ligament proper; but very
412 THE REGION OF THE WRIST AND THE HAND.

often it appears to be simply a downward prolongation from that ligament
over the palm, the tendon of the palmaris longus losing itself in the upper
margin of the ligament. The palmar fascia consists chiefly of strong longi-
tudinal fibres, which constitute the outer or superficial layer, and can be
separated by careful dissection (Plate 48, Fig. 2, No. 8) from a deep layer
of transverse fibres which are in immediate relation with the lower border
of the annular ligament. At the borders of the thenar and hypothenar
eminences the palmar fascia becomes thinner, and a layer composed of
the deeper transverse fibres passes over the muscles forming these emi-
nences to blend with the dorsal fascia. Toward the fingers the fascia
divides into four slips, which are inserted chiefly into the bases of the
proximal phalanges and the anterior surfaces of the capsular ligaments
of the metacarpo-phalangeal joints, while some of the deeper fibres form
lateral slips which blend with the aponeurotic sheaths of the flexor
tendons, and others pass round and join the dorsal aponeurosis over
the extensor tendons. In the arches formed by the attachment of the
slips there are little cushions of fatty tissue which enclose the digital
nerves and arteries and the tendons of the lumbricales muscles as they
pass to the fingers. Many of the fibres of the superficial layer of the
fascia are associated with the skin, which renders its dissection from the
fascia very tedious. From the deeper layer there are two weak slips which
pass across to be attached to the lateral expansions enclosing the muscles
of the thenar and hypothenar eminences. The one to the thumb is espe-
cially noticeable (Plate 48, Fig. 1, No. 4). From the under surface septa
also pass to the metacarpal bones. Beneath the skin of the webs of the
fingers there are transverse fibres, called the superficial transverse ligaments,
which cross over the vessels and nerves and afford them greater protection
from pressure when the hand is used in grasping. The palmar fascia,
like all the expansions of the deep fascia, is subject to great variability,
depending upon development. In the hands of mechanics it is always
very strong, and among persons who habitually use their fingers requiring
effort doubtless many accessory slips are produced. The ulnar artery and
ulnar nerve descend to the palm over the annular ligament and between
the two layers of the palmar fascia (Plate 48, Fig. 2, Nos. 11 and 12).
THE REGION OF THE WRIST AND THE HAND. 413

The anterior annular ligament consists of a strong transverse band -
of fibrous tissue arching across from the unciform process and the pisi-
form bone to the trapezium and the tuberosity of the scaphoid bone. It
is continuous with the deep fascia of the forearm above and with the deep
layer of the palmar fascia below. Most of the muscles of the ball of the
thumb and of the little finger arise from it (page 404), and it holds in
place the flexor tendons of the fingers and thumb and the median nerve
(Plate 48, Figs. 2, 3, and 4). The anterior annular ligament is one of the
most unyielding fibrous structures in the body. There are two synovial
sacs placed beneath this ligament: one, the larger, lines the canal formed
by the ligament arching across the carpus, and is reflected over the flexor
tendons of the fingers so as to form a loose pouch four centimetres, or one
and a half inches, above the ligament, while below it sends prolongations
along the several tendons, forming sheaths for them as far as the middle
of their corresponding metacarpal bones, except the little finger, which
usually is accompanied by an extension as far as the attachment of the
flexor profundus tendon at the base of the ungual phalanx. The smaller
synovial sac is in relation to the flexor longus pollicis tendon, and extends
above the annular ligament not quite so far as the other sac. It accom-
panies the tendon as far as its insertion into the ungual phalanx of the
thumb. The tendons of the index, middle, and ring fingers are provided
with separate synovial sheaths, which rarely communicate with the other
synovial sacs, they being about two centimetres, or three-quarters of an
inch, apart. The highest points of the digital sheaths usually correspond
to the third flexion-line on the palmar surface, while they terminate at
the bases of the ungual phalanges, so that the finger-pulps rest upon the
periosteum, a fact which is often demonstrated in felon, or whitlow, by
the rapid necrosis affecting the bones. This arrangement explains the
fact that an abscess involving the thumb or the little finger is apt to
spread to the forearm, while such an extension of suppuration does not
often follow a similar affection of any of the other fingers.

The ulnar artery descends from the forearm in close relation to the
pisiform and unciform bones, with the ulnar nerve close to its inner side.
‘At the wrist both artery and nerve are embedded in adipose tissue and
414 THE REGION OF THE WRIST AND THE HAND.

protected by an expansion from the tendon of the flexor carpi ulnaris
to the palmaris longus. ' Just after leaving the pisiform bone the wlnaris
profunda is given off, and, accompanied by the deep branch of the ulnar
nerve, passes between the abductor minimi digiti and flexor brevis minimi
digiti muscles, while the main vessel continues between the two layers of
the palmar fascia along the muscles of the ball of the little finger, two cen-
timetres, or three-quarters of an inch, from and parallel with the linea
vitalis on the surface. About midway between the latter and the linea
cephalica the ulnar artery turns outward toward the web of the thumb,
and, crossing over the branches of the median nerve and flexor tendons,
anastomoses either with the radialis indicis or with the superficialis vole
artery, and sometimes with both, thus forming the superficial arterial
palmar arch (Plate 48, Figs. 38 and 4). This arch is about six centi-
metres, or not quite two and a half inches, above the interdigital clefts.
From the upper border or concavity of the arch several small recurrent
branches arise which supply the carpal bursa and palmar fascia and
inosculate with the carpal branches of the radial artery. From the
lower border or convexity of the arch arise four digital arteries, which
supply the fingers, except the radial side of the index and the thumb.
The first descends over the muscles on the inner border of the palm to
the ulnar side of the little finger, along which it runs to the tip. The
second, third, and fourth descend vertically between the flexor tendons
and on a line with the clefts between the fingers. About one and a half
centimetres, or half an inch, above the clefts each artery, after receiving
a communicating branch from the deep arch, bifurcates into two branches,
which proceed along the opposed sides of the fingers as far as their tips.
The lateral digital arteries in their courses freely communicate by trans-
verse branches at the several joints, which they supply, as well as the
sheaths of the tendons on both the palmar and dorsal surfaces. At the
ungual phalanges the digital arteries subdivide into palmar and dorsal
branches, which form plexuses in relation to the pulps of the fingers
and the matrices of the nails respectively. ;
The radial artery enters the palm from the dorsal surface between the
inner head of the flexor brevis and the adductor pollicis muscle (page 405),
THE REGION OF THE WRIST AND THE HAND. 415

and, after giving off the arteria princeps pollicis and the radialis indicis,
continues inward as the palmaris profunda, under the branches of the
median nerve and the flexor tendons, to anastomose with the ulnaris pro-
funda and thus form the deep arterial paimar arch (Plate 48, Fig. 4).
This arch is seven centimetres, or two and three-quarter inches, above the
interdigital clefts. The arteria princeps pollicis at its origin is of large
size, and passes between the abductor indicis (or first dorsal interosseous)
and the adductor pollicis to the ulnar side of the palmar surface of the
metacarpal bone of the thumb. In the interval between the lower portions
of the flexor brevis muscle it divides into two lateral branches, which run
along one or each side of the thumb and inosculate with each other simi-
larly to the other digital arteries. The radialis indicis artery descends
from its origin to the radial side of the index finger. Usually at the
lower border of the adductor pollicis muscle this vessel communicates with
the superficial palmar arch, and it often receives a branch from the prin-
ceps pollicis (Plate 48, Figs. 8 and 4). The deep arch receives three per-
forating branches from the dorsal carpal rete through the spaces between
the metacarpal bones, and from its upper border gives off branches to the
adjacent muscles and branches to the anterior carpal rete. From its lower
border four smal] branches descend in relation to the palmar interosseous
muscles and communicate with the digital arteries from the superficial
arch, as above described. Occasionally one or more of these interosseous
branches are substituted for the regular arteries to the fingers.

Wounds of the palm involving any of the principal arteries are always
serious, in consequence of the free anastomoses between the vessels form-
ing the arches, and of the difficulty of reaching the bleeding vessel and
securing it in the wound without damaging other important structures.
Nevertheless, the above procedure is the only proper one, as the hemor-
rhage can rarely be checked by tying either one or both of the main
arteries above the wrist.

The wlnar nerve, after passing over the anterior annular ligament at
the wrist, on the inner side of the ulnar artery, divides into a deep and
a superficial palmar branch. The deep palmar branch supplies the muscles
forming the hypothenar eminence, and accompanies the ulnaris profunda
416 THE REGION OF THE WRIST AND THE HAND.

artery to supply all the interosseous muscles, the two ulnar lumbricales,
the adductor pollicis, the inner head of the flexor brevis pollicis, and the
carpo-metacarpal and metacarpo-phalangeal articulations. The superficial
palmar branch distributes filaments to the skin over the hypothenar emi-
nence and the inner’ surface of the palm of the hand, and to the palmaris
brevis muscle, and divides into two digital nerves, one to the ulnar side
of the little finger and the other subdividing and supplying the opposed
sides of the ring and little fingers (Plate 48, Fig. 4, and Plate 53, Fig.
8). The superficial branch of the ulnar communicates with the median
nerve by a branch which passes beneath the superficial palmar arch.

The median nerve (Plate 48, Figs. 3 and 4), as it descends from the
forearm under the anterior annular ligament, is enveloped in a fold of
the synovial membrane. It is superficial to the flexor tendons, and as it
enters the palm becomes somewhat swollen, of a pinkish color, and flat-
tened, and divides into two branches of nearly equal size. The external
palmar branch supplies recurrent filaments to the muscles of the ball of
the thumb (the abductor pollicis, the opponens pollicis, and the outer
head of the flexor brevis pollicis), and ends in three digital nerves, two
to the thumb and one to the radial side of the index finger. The nerves
to the thumb pass one on each side of the long flexor tendon as far as
the ungual phalanx, where the outermost nerve connects with the ter-
minal branch from the radial nerve. The nerve to the radial side of the
index finger sends a filament to the first radial lumbrical muscle, and is
continued to the ungual phalanx. The internal palmar branch of the
median nerve divides into two digital branches, which pass vertically in
a line with the clefts between the index and middle and the middle and
ring fingers. About three centimetres, or one inch and a quarter, above
the webs of the fingers the digital branches subdivide into lateral digital
nerves, which are distributed as follows. The nerves from the first branch
pass to the opposed sides of the index and middle fingers. The first digital
branch also supplies the second radial lumbrical muscle, The nerves
from the second branch pass to the opposed sides of the middle and ring
fingers, receiving communicating branches from the ulnar nerve.

After many careful dissections, and repeated critical examinations on
THE REGION OF THE WRIST AND THE HAND. 417

the living regarding the cutaneous distribution of the various digital
nerves, the author is inclined to believe that the arrangement as shown
(Plate 53, Figs. 2 and 3) may be considered to represent their usual rela-
tions. It should be remembered that there is commingling of the fibres
of the median and ulnar nerves by direct intercommunicating nerves both
above and below the wrist, which probably accounts for the discrepancy
in the observations on this subject. The extremities of the digital nerves
are provided with peculiar little bodies, the Pacinian corpuscles, which are
found in greater number on the nerves of the thumb and the index finger.
Their function is unknown. The cutaneous nerve-supply of the hand is
remarkable for the high development and the great number of the ¢actile
corpuscles, which give to it an extraordinarily acute degree of tactile sensi-
bility. The most sensitive area is the palmar surface of the tips of the
fingers, and especially that of the ungual phalanx of the index finger.
The dorsal surface of the hand is the least sensitive, as already stated.

The superjicial lymphatic vessels commence by palmar and dorsal vessels
on each finger, which unite and form plexuses on the palmar and dorsal
surfaces of the hand respectively. Those of the palmar plexus are small
and very close, and are arranged in an arch, from which vessels pass up
the forearm accompanying the superficial veins. Those of the dorsal
plexus are comparatively larger and more numerous, and their vessels
wind round the borders of the forearm above the wrist and join with the
vessels from the palmar plexus. The deep lymphatic vessels accompany
the vene comites of the radial and ulnar arteries.

The nails are the horny plates which surmount the finger-tips upon
their dorsal surfaces, and may be regarded as modified appendages of the
epidermis. Each nail rests upon the extremely vascular and sensitive
nail-bed of the dermis, the upper portion of which is called the matria,
whose papille are arranged in ridges and protected by a fold of the skin.
The part of the nail in relation to the matrix is the root. It is the thin-
nest part, and appears white and opaque just in front of the fold of the
skin, and, owing to its crescent shape, is called the dunula. The latter
is always more pronounced in the thumb than in the fingers. The growth

of the nails is like that of the epidermis, by an incessant production of
53
418 THE REGION OF THE WRIST AND THE HAND.

nail-cells in the nail-bed, so that as long as the matrix is preserved the
nail is capable of reproduction. The nails vary in individuals, and under
certain constitutional conditions are probably influenced by impeded cir-
culation, for there appears to be a direct communication between the
arteries and the veins in the matrix. It is noteworthy that during con-
valescence from many of the exanthematous diseases grooves make their
appearance across the nails, presenting indications of growth. As the
digital nerves supply large terminal filaments to the nail-beds, it is not
difficult to account for the intense pain which is experienced when a
splinter or other foreign body is thrust beneath the nails.

The development of the bones of the wrist and hand occurs at varying
periods. At birth the carpal bones are all cartilaginous. The os magnum
becomes ossified in the first year, the unciform in the second, the cuneiform
in the third, the trapezium in the fourth, the semilunar in the fifth, the
scaphoid in the sixth, the trapezoid in the seventh, and the pisiform not
generally before the twelfth.

The metacarpal bones and the phalanges are usually composed of a
shaft and an upper epiphysis. The shafts become ossified soon after
birth, and the epiphyses are all united about the twentieth year.
INDEX RSOSYOLUME L

THE REFERENCES TO SURGICAL AFFECTIONS OR PROCEDURES (MARKED 2) RELATE TO THEIR ANATOMY ONLY,

A.

Abducent nerve, 41, 92.
* Abscess, deep-seated, of the temporal
region, 150.
mammary, 250.
mediastinal, 322.
pharyngeal, 133.
post- pharyngeal, 195.
Acervulus cerebri, 51.
Acoustic hair-cells, 77.
Acromion process, 330.
Ale of the nose, 109.
Alveoli of the jaws, 145.
of the lungs, 269.
of the parotid gland, 131.
Awmpulle of the semicircular canals,
72.
* Amputation of the arm, 349, 361.
of the elbow-joint, 371.
of the forearm, 396.
of the shoulder-joint, 337.
Amygdalz of the cerebellum, 47.
Anastomosis of arteries, 292.
Andersch, ganglion of, 205, 219.
#* Anéurism of the aorta, 288.
Annular ligament of the wrist, ante-
rior, 413.
of the wrist, posterior, 407.
Annulus ovalis, 278.
Ansa hypoglossi, 205.
Anterior nares, 114.
Antihelix, 61.
fossa of, 61.
Antitragus, 61.
Antrum, mastoid, 6.
of Highmore, 113, 144.
walls of, 145.
Aorta, 287.
absence of arch of, 289.
arch of, highest point to which
it reaches, 289.
ascending, or ventral, 287.

 

Aorta, branches of, 288.
bulbous enlargement of, 287.
descending thoracic, 312.
interior of, 288.
normal course of, 287.
opening into, 284.
transverse, 288.
Aponeurosis, digital, 386.
dorsal, of the fingers, 403.
of the sealp, 13.
pharyngeal, 171.
Appendix of the left auricle, 282.
of the right auricle, 277.
Application of tourniquet to the
brachial artery, 353.
Aqueduct of Fallopius, 69, 204.
of Sylvius, 39, 44, 50.
of the cochlea, 73.
of the vestibule, 72.
Aqueous humor, 100, 102.
Arachnoid fluid, or cerebro-spinal
fluid, 21.
membrane, 21.
Arantius, ventricle of, 50.
Arbor vite of the cerebellum, 49.
Arch of the aorta, 289.
of the upper jaw, 147.
Arciform fibres, 45.
Areus senilis, 88.
Areola of the breasts, 250.
Arm, bicipital depressions of, 349.
region of, 348.
subcutaneous fascia of, 349.
surface-marking of, 349.
Arnold’s nerve, 63, 204.
Arteria centralis modioli, 73.
retina, 94,
comes nervi phrenici, 259.
Arterial arch, deep palmar, 415.
superficial palmar, 414.
pulse, 307. |
Arteriosum, ligamentum, 305.
Arteriosus, ductus, 290, 303.

 

Artery or arteries:
acromial, 341,
descending, 349.
acromio-thoracie, 341.
alar thoracic, 341.
anastomotica magna of brachial,
355.
angular, 124,
anterior cerebral, 22.
ciliary, 96.
circumflex, 342.
communicating, 22.
dental, 141.
interosseous, 392.
mediastinal, 233, 259.
articular, to the elbow-joint, 391.
to the shoulder-joint, 233.
ascending palatine, 159.
pharyngeal, 175.
auditory, 23, 78.
axillary, 229, 339.
branches of, 341.
basilar, 22, 215, 232.
bicipital, 343.
brachial, 354.
at the elbow, 369.
branches of, 354.
compression of, 369,
course of, 351.
high bifurcation of, 356.
in relation to the median
nerve, 356,
* ligation of, 356.
venz comites of, 357.
bronchial, 270, 313.
buccal, 141.
capacity of, 291.
capillary, of the heart, 276.
carotid, 223.
course of, 201.
* ligation of, 226.
carpal, 389.
circumflex, 334.

419
420

Artery or arteries:

collateral intercostal, 313.
common carotid, bifurcation of,
201.
interosseous, 392.
pulmonary, 282, 289.
communication with veins in the
matrices of the nails, 418.
coronary, 148, 277.
cortical, 23.
course of, inthe extremities, 293.
in various localities, 291.
erico-thyroid, 184.
*in relation to laryngot-
omy, 184.
cubital, 355.
deep temporal, 141.
descending acromial (thoracica
humeraria), 341.
palatine, 141.
digital, 414.
dimensions of, 292.
dorsal, 315.
interosseous, of the hand,
409.
of the tongue, 166.
dorsalis scapule, 331, 342.
* effect of ligation upon, 295.
endangium of, 295.
ethmoidal, 95.
external and internal carotid,
relative position of, 203.
carotid, 34.
branches of, 203.
coat, or adventitia, 293.
mammary, 250, 341.
facial, 123, 203.
frontal, 8, 95.
ganglionic, 23.
general anatomy of, 293.
great or middle meningeal, 17.
hypogastric, 304.
inferior coronary, 123.
dental, 139.
labial, 123.
laryngeal, 233.
profunda, 355.
thyroid, 233, 235,
infra-orbital, 141.
innominate, 121, 288.
bifurcation of, 141.
* ligation of, 222.
intercostal, 313.
dorsal branches of, 209.
internal carotid, 134, 203.
in relation to the phar-
yux, 175.
coat, or intima, 298.

 

INDEX.

Artery or arteries:

internal mammary, 257.
* ligation of, 257.
maxillary, 134, 139, 203.
interosseous, of the palm, 415.
lachrymal, 95.
lateral digital, 414.
infracostal, 259.
of the nose, 124.
spinal, 215.
lateralis nasi, 110.
left common carotid, 288.
subclavian, 288.
Jenticulo-striate, 23.
lesser meningeal, 17, 139.
lingual, 166, 203.
* ligation of, 166.
long and short sub-scapular, 341.
thoracic, 341.
lower intercostal, 257.
mammary branches of anterior
intercostal, 250.
masseteric, 139.
meningeal, 17.
from occipital, 211.
middle cerebral, 22.
coat, or media, 293.
meningeal, 139.
mode of division of, 292.
muscular branches of brachial,
354,
of radial, 389.
of ulnar, 392.
musculo-phrenic, 257.
mylo-hyoid, 139.
nasal, 95.
from internal maxillary,
115.
or spheno-palatine, 141.
nutrient, to the humerus, 355.
occipital, 8, 203, 211.
cesophageal, 313, 317.
of the brain, 22.
of the breasts, 250.
of the choroid coat, 97.
of the dura mater, 17.
of the face, 123.
of the larynx, 184.
of the nasal cavities, 115.
of the nose, 110.
of the palate, 159.
of the pericardium, 274.
of the pinna, 63.
of the scalp, 8.
hemorrhage from, 9.
of the tympanum, 7].
ophthalmic, 94.

osculation or anastomosis of, 292. ,

 

Artery or arteries :

palmar and dorsal, of digital,
414,
palmaris profunda, 415.
palpebral, 95.
perforating, of deep palmar arch,
409, 415.
of the thorax, 259.
pericardiac, 313.
petrosal, from middle meningeal,
71,
phrenic, 322.
posterior auricular, 8, 134, 203.
carpal, 409.
cerebellar, 23. .
cerebral, 23. _
circumflex, 342, 346.
communicating, 22.
dental, 115.
interosseous, 392.
palatine, 158.
scapular, 330, 342.
princeps cervicis, 211.
pollicis, 415.
pterygo-palatine, 141.
pterygoid, 141.
pulmonary, 290.
radial, 389.
and ulnar, variable origins
of, 343.
in the hollow formed by the
extensor tendons of the
thumb, 409.
in the palm, 414.
radialis indicis, 415.
ranine, 162, 166.
recurrent, of posterior interos-
seous, 392.
radial, 389.
ulnar, 392.
right and left coronary, 276.
septal, 141.
short ciliary, 97.
small thoracic, or pectoral, 341.
spinal, 313.
structure of walls of, 293.
subclavian, 221, 227.
differences of right and left,
228.
* ligation of, 231.
sub-lingual, 166.
sub-scapular, 342.
superficial cervical, 206, 233.
superficialis vole, 389.
superior coronary, 124.
dental, 141.
epigastric, 257.
intercostal, 211.
Artery or arteries:
superior laryngeal, 184.
profunda, 354.
thoracic, 341.
thyroid, 203, 235.
supra-hyoid, 166.
supra-orbital, 8, 95.
supra-scapular, 221,
233.
stylo-mustoid, 71, 78.
systemic, 291.
temporal, 8, 134, 203.
terminal, 23, 292.
thoracica humeraria, 341.
thoracico-acromial, 250.
thyroid axis, 229, 232.
thyroidea ima, 221, 235.
to the concha, 211.
tonsillar, of facial, 171.
tracheal, 237.
transversalis colli, 206, 221, 233.
transverse facial, 124, 134.
tympanic, 139.
ulnar, 391, 393.
at wrist, 413.
recurrent, 391.
ulnaris profunda, 414.
umbilical, 304.
vas aberrans, 352, 355.
vertebral, 215, 232.
groove for, on atlas verte-
bra, 213.
vessels of, 299.
Vidian, 141.
Asterion, 60.
Auditory artery, 23, 78.
canal, walls of, 64.
hairs, 75.
meatus, external, 63.
cartilaginous portion of, 64.
osseous portion of, 64.
nerves, 41, 77.
vein, 78.
Auricle of the ear, 60.
left, of the heart, 282.
right, of the heart, 278.
Auricles, walls of, 278.
Auricular appendix, 282.
branch of pneumogastric nerve,
63.
cartilage, 61.
ligaments, 61.
muscles, 61.
Axilla, connective tissue of fat in,
338,
lymphatic glands of, 346.
region of, 337.
suspensory ligament of, 338.

229, 231,

 

INDEX.

* Axillary abscess, 338.
artery, 339.
* ligation of, 343.
line of, 343,
fascia, 338.
fold, 338.
glands, involvement of, in can-
cer, 347.
* removal of, 347.

B.

Bartholin, duct of, 164.
Base of the cerebrum, 37.
Basilar artery, 22.
Basilic vein, 351.
Basion, 35.
Bell, external respiratory nerve of,
345.
Bichat, fissure of, 29.
Bicipital groove of the humerus, 332.
Blind spot, 105.
Blood, 300.
amceboid movement of, 301.
arterial, 290.
circulation of, after birth, 305.
before birth, 303.
corpuscles, red and white, 300.
differentiation of its circulation
before and after birth, 305.
hematoblasts, 301.
hemoglobin of, 301.
plates, 301.
Blue line in lead-poisoning, 150.
Bodies, olivary, 45.
restiform, 45.
Body, interearotic, 203.
thyroid, 233.
Bone or bones:
body of sphenoid, 111.
carpal, 396.
clavicle, 323.
cribriform plate of ethmoid, 111.
cuneiform, 396.
humerus, 348.
hyoid, body of, 165.
greater and lesser cornua
of, 165.
position of, 165.
incisive, 147.
incus, 68.
inferior maxillary, development
of, 152.
mylo-hyoid ridge of, 165.
variations in angle of, 153.
lachrymal, 79.
Inagnum, 395.
malar, 80, 145.

 

421

Bone or bones:
malleus, 67.
maxillary, ossification of, 150.
metacarpal, 399.
nasal, 107.
of the ear, 67.
of the forearm, “fractures of,
394.
of the head, 2.
of the orbits, 80.
of the palate, 111.
of the wrist, ossification of, 418.
phalanges, 401.
pharyngeal spine of occipital,
172.
pisiform, 396.
premaxillary, 147.
radius, 363, 373.
ribs, 243.
seaphoid, 399.
scapula, 328.
semilunar, 396.
sesamoid, 402.
sphenoidal turbinated, 111.
stapes, 68. ‘
sternum, 246.
superior maxillary, 144.
* excision of, 145.
palate processes of, 156.
tuberosity of, 141.
temporal, 7.
trapezium, 396.
trapezoid, 396.
turbinated, 111.
ulna, 362, 373.
unciform, 396.
vertebra, cervical, 187.
dorsal, 248,
vomer, 108.
Wormian, 5.
Brachia, 52.
Brachial artery, 354.
high bifurcation of, 356.
or axillary plexus of nerves,
344,
plexus of nerves in the arm, 357.
Brain, 24.
area of surface of, 25.
arteries of, 22.
convolutions of, 25.
development of, 25.
fifth ventricle of, 53.
fourth ventricle of, 49.
furrows of, 25.
lateral ventricles of, 53.
lobes of hemispheres of, 26.
median or longitudinal fissure
of, 26.
422

Brain, membranes of, 15.
motor area of, 35.
sengorial aren of, 36.
size and shape of, 25.
structure of, 25.
thjrd ventricle of, 51.
Breast, 250.
* operation for removal of, 251,
253.
Breathing, abdominal, 248.
thoracic, 248.
Bregma, 2, 33.
Bridge of the nose, 108.
Broca, convolution of, 30.
Bronchi, 268.
right and left, 236.
structure of, 268.
Bronchial glands, 271.
tube, 268.
Bronchioles, 269.
Bronchocele, 235.
Bulb, olfactory, 38.
Bursa in relation to the tendor of
the biceps muscle, 352.
in relation to the tendon of the
coraco-brachialis muscle, 353.
in relation to the tendon of the
flexor carpi radialis muscle,
380.
in relation to the tendon of the
sub-scapularis muscle, 353.
in relation to the tendon of the
trapezius muscle, 209.
sub-deltoid, 334.
Burse about the elbow, 370.

Cc.

Calamus scriptorius, 50.
Calcar, 55.
Canal or canals:
anterior dental, 145.
central, of Stilling, 105.
infra-orbital, 127, 145.
lachrymal, 113.
membranous semicircular, 75.
naso-palatine, 156.
of Huguier, 71, 143.
of Petit, 103.
of Schlemm, 96, 102.
palatine, 147.
posterior dental, 145.
semicircular, 72.
spiral, 73.
Vidian, 142.
Canaliculi of the eyelids, 85.
Canalis reuniens, 75.
spiralis modioli, 73.

 

INDEX.

Canthi, 81.

Capillaries, 298.
calibre of, 298.
in various tissues, 298,
medullary, 224.
pulmonary, 270.
structure of, 298,

Capitulum, 348.

Capsule, external, 54,
internal, 54.
of Tenon, 89, 93.

Carotid tubercle, 189.

Carpal bones, 396.
rete, 392, 415.

Carpus, 396.

Cartilage or cartilages:
accessory, in female larynx, 179.
arytenoid, 177.
auricular, 61.
costal, 245,
cricoid, 177.

hoop of, 177, 189.
relations of, 190.
ensiform, 247,
lateral, of the nose, 108.
of Wrisberg, 178.
septal, of the nose, 108.
sesamoid, 109.
tarsal, 81.
thyroid, 176.
cornua of, 176.
Cartilaginous framework of the nose,
108.

Caruncula lachrymalis, 85,

Caudate nucleus, 54.

Caudo-lenticular limb, 55.

Cavernous sinuses, 19.

Cavity, glenoid, of scapula, 331.

of temporal bone, 136.

Cavum oris, 156.

Cells, acoustic hair-, 77.
anterior ethmoidal, 113.
gustatory, 162.
mastoid, 6.
migratory, 301.
of Deiters, 77.
olfactory, 114, 116.
pigment-, of choroid coat, 97.
posterior ethmoidal, 113.

Cerebellum, 26, 47.
central lobe of, 47.
function of, 49.
vermiform process of, 47.

Cerebrum, base of, 37.
convolutions of, 25.
crura of, 39.
fibres of medullary substance of,

58,

 

Cerebrum, fissures of, 27.
hemispheres of, 26.
lobes of, 26.
lower level of, 33.
ventricles of, 49, 51, 53.
Ceruminous glands, 64.
Cervical axillary passage, 339.
Chamber, anterior, 102.
posterior, 102.
Cheeks, 149.
Chest, physical examination of, 311.
Chorde tendinem, 281, 283..
vocales, 178, 179.
Willisii, 19.
Choroid coat of the eye, 97.
plexuses, 52.
tela, 21.
Ciliary body, 99.
processes, 99.
Cirele of Willis, 22.
Circulation, foetal, 303.
pulmonary, 306.
systemic, 305.
Cireulus major, 101.
minor, 101.
Claustrum, 54,
Clava, 46.
Clavicle, 324.
acromial end of, 324.
borders of, 325.
* fractures of, 327,
movements of, 324,
ossification of, 327.
physical properties of, 323.
sternal end of, 324,
subclavian impression of, 325. -
Cochlea, 73.
Cochlear canal, 73, 74.
duct, 75.
Cohnheim, terminal arteries of, 23.
Collateral circulation, 292.
after ligation of the axil-
lary artery, 343.
after ligation of the carotid
artery, 227.
after ligation of the sub-
clavian artery, 232.
Columnz carne, 279, 283.
nasi, 109.

Commissura simplex, 47.
Commissure, great transverse, 57.
of the third ventricle, 57.

Conarium, 51.

Concha, 61.

Conjunctiva, 85.
blood-vessels of, 86.
corneal, 87.
palpebral and ocular, 85, -
Conjunctiva, sclerotic, 86.

Conus arteriosus, 279.

Convolution or convolutions:
angular, 31.
annectant, 31.
anterior central, or ascending

frontal, 30.
ascending parietal, 31.
Broca’s, 30.
fornicate, 32.
frontal, 30.
hippocampal, 32.
of the brain, 25.
parietal, 31.
retro-insular, 32.
superior marginal, 31.
Coracoid process, 330.
Cord, spinal, enlargement of, opposite
the fifth cervical vertebra, 215.
Cords of the brachial or axillary
plexus of nerves, 345.

Cornea, 87.
lamina of, 87.
nerves of, 88.
non-vascularity of, 88.
proper substance of, 87.

Corneal corpuscles, 87.

Corniculum laryngis of Santorini,

178.

Cornua Ammonis, 55.
of lateral ventricles, 53.

Corona radiata, 58,

Coronoid process, 362.

Corpora albicantia, 39.
geniculata, 52.
quadrigemina, 50.
striata, 52.

function of, 58.
topographical relation of, 59.
Corpus albicans, 53.
Arantii, 282,
callosum, 57.
peduncles of, 37.
ventricles of, 58.
dentatum, 45.
fimbriatum, 53.

Corpuscles of the blood, 300.
Pacinian, 417.

Corti, organ of, 74.
rods of, 77.
tunnel of, 77.

Costal cartilages, 245.

Costoecoracoid membrane, 338.

Cranial nerves, 38.

deep origins of, 44.

Cranio-cerebral topography, 32.

Crista, 72.
acoustica, 75.

 

INDEX.

“Crow’s-feet,” 82.
Crura cerebri, 39.
of the cerebellum, 49.
of the fornix, 52.
Crusta, 39.
Crystalline lens, 102.
Cuneiform cartilages, 178.
Cupola, 73. ;
Curved line of the occipital bone, 6.
Cutaneous muscle of the scalp, 11.

D.

Deciduous teeth, 151.
Decussation.of the optic nerve, 38.
Deep fascia of the arm, 351.
of the forearm, 379.
Deltoid muscle, 334.
insertion of, 335.
Diaphragm, 249, 320.
aortic opening of, 321.
arteries of, 322.
central tendon of, 320.
crura of, 321.
height of arches of, in respira-
tion, 322.
leaflets of, 321.
muscular portion of, 321.
nerves of, 322.
observations upon contractions
of, 273.
oesophageal opening of, 321.
opening for inferior vena cava,
321.
relations of upper surface to
contents of thorax, 309.
tendinous arches of, 321.
Diastole of the heart, 277.
Digital extremities or phalanges, 396.
Diploe, 3.
Diploie structure of the skull bones,
14,
veins, 15.
Direct sensory tracts, 58.
Disk, intervertebral, 241.
* Dislocation of elbow, 370.
* of shoulder, 336.
Double chin, 191.
Duct, cochlear, 75.
lymphatic, 227.
nasal, 80, 113.
of Bartholin, 164.
of Rivinus, 164.
of Stenson, 131, 149.
of Wharton, 165.
thoracic, 227, 232, 318.
termination of, 318.
valves of, 318.

 

423

Ductus arteriosus, 290, 303, 304.
reuniens, 77.”
venosus, 304.
Dura mater, 15.
arteries of, 17.
lateral sinuses of, 18,
nerves of, 19.
sinuses of, 18.
veins of, 15S.

E.

Ear, external meatus of, 60.
region of, 60.
Ear-stones, 75.
Elbow, dislocations of, 370.
fractures in relation to, 371.
landmarks of, 367.
movements of, 365,
passive motion of, after injuries,
365.
region of, 362.
superficial veins of, 367.
Elbow-joint, 363.
* amputation of, 371.
injuries to, 372.
resection of, 371.
Eminence, auditory, 50.
eanine, 144.
cinereous, 50.
frontal, 5, 33.
hypothenar, 409.
parietal, 6, 33.
thenar, 409.
Eminentia collateralis, 55.
Emissary veins, communications of,
18.
from the cochlea, 79.
Encephalon, 24.
Endocardium, 248.
Endolymph, 74.
Epicardium, 275.
Epicondyle, internal and external,
348.
Epicranium, 13.
Epiglottis, 178.
Epistaxis in relation to the superior
longitudinal sinus, 19.
Eustachian tube, 67, 173.
pharyngeal opening of, 112.
valve, 278, 303.
External capsule, 54.
meatus of ear, 60.
Extremity, upper, 223.
Eye, 79.
accommodation of, for vision,
101. ;
dangerous area of, 99.
424

Eyeball, 96.
Eyebrow, 80.
Eyelashes, 83,
Eyelids, 81.

F.

Face, arteries of, 123.
deep structures of, 136.
development of, 150.
fat in subcutaneous tissue of,
11%.
landmarks of, 116.
lymphatic vessels of, 125.
muscles of, 119.
region of, 116.
sensory nerves of, 125,
skin of, 116.
Facial artery, 123.
markings, 117.
nerves, origin of, 41.
vein, 125.
Fallopius, aqueduct of, 69.
Falx cerebelli, 16.
cerebri, 16.
Fascia, axillary, 338.
bicipital, 351, 368.
bucco-pharyngeal, 149.
deep cervical, 193.
development of, 197.
external layer of, 194.
influence of, against atmos-
pheric pressure, 197.
internal layer of, 195.
reflections of, 194.
dentata, 29, 57.
extra-pleural, 262.
laryngeal, 179.
masseteric, 123.
of the arm, 351.
over the anterior surface of the
thorax, 353.
palmar, 411.
parotid, 130.
post-pharyngeal, 175.
prevertebral, 195.
subcutaneous, over the arm, 349,
temporal, 14,
Fasciculi teretes, 46, 50.
Fauces, 170.
Fenestra ovalis, 66.
rotunda, 66.
Fibres, association, 59.
of medullary substance of the
cerebrum, 58.
Fibro-cartilage, inter-articular, 136.
intervertebral, 215.
triangular, 397.

 

INDEX.

Fissura palpebrarum, 81.
Fissure, anterior median, of medulla
oblongata, 44.
ealearine, 29.
central, of Rolando, 30.
dentate, 57.
Glaserian, 66, 139.
hippocampal, 29.
in upper lip, 149.
interparietal, 29.
intra-lobular, of brain, 30.
longitudinal, 26, 57.
of Rolando, 27.
of Santorini, 61.
of Sylvius, 27.
branches of, 27.
parieto-occipital, 29.
posterior median, of medulla ob-
longata, 45.
primary, of brain, 27.
secondary, of brain, 27.
spheno-maxillary, 80.
sphenoidal, 79.
transverse, of Bichat, 29.
Flocculus of the cerebellum, 47.
Foetal circulation, 303.
heart, 303.
Fold or folds :
aryteno-epiglottic, 178.
axillary, 338.
gleno-humeral, 334.
glosso-epiglottic,. 163.
vestigial, 275.
Follicles, sebaceous, of nose, 109,
Fontanelles, 3.
Foramen or foramina :
anterior condyloid, 167.
excum of frontal bone, 10, 115.
of medulla oblongata, 45.
of tongue, 161.
dental, 139.
ethmoidal, 80.
in transverse process of sixth
cervical vertebra, 215.
infra-orbital, 127, 144.
intervertebral, 315.
jugular, 203.
magnum, 232.
mastoid, 6.
mental, 139.
of Magendie, 21, 50.
of Monro, 51.
of Scarpa, 147.
of Stenson, 147.
of Vesalius, 125.
optic, 79.
ovale, of the heart, 278.
of the sphenoid bone, 139.

 

Foramen or foramina:
parietal, 6.
spinosum, 139.
stylo-mastoid, 69.
supra-orbital, 5.
supra-trochlear, 348.
Thebesii, 279.
* Forearm, amputation through the
middle of, 396.
bones of, in relation to surfaces,
376.
branches of radial artery in,
389.
of ulnar artery in, 391.
contour of, 377.
cutaneous nerves of, 378.
deep fascia of, 379.
movements of, in pronation and
supination, 376.
muscles of, 379.
region of, 372.
Formatio reticularis, 46.
Fornix, 51.
anterior pillars of, 52.
conjunctive, 85.
erura of, 52.
Fossa, antecubital, 352, 367.
anterior nasal, 107.
canine, 144.
coronoid, 348.
hyaloid, 103.
incisive, 144.
infra-spinous, of seapula, 233.
jugular, 203,
lachrymal, 80.
nasal, 111.
olecranon, 348.
ovalis, of the antihelix, 61.
of the heart, 278.
scaphoidea, 61.
spheno-maxillary, 142.
supra-spinous, of scapula, 233.
Fovea, anterior, 50.
centralis of retina, 105.
hemi-elliptica, 72.
hemisphzrica, 72.
posterior, 50.
* Fracture or fractures :
at base of skull, symptoms of, 7.
Barton’s, of wrist, 373.
Colles’s, 395.
green-stick, of clavicle, 327.
of bones of forearm, 394.
of clavicle, 327.
of elbow, 370.
of humerus, 261,
of petrous portion of temporal
bone, 78.
* Fracture or fractures:
of ribs, 245.
of shoulder, 337.
of skull by contre-coup, 15.
Frena Jabiorum, 149.
Frenula, 47.
Frenum epiglottidis, 163.
linguee, 162.
Friction-sound consequent upon in-
flammation of the pleura, 261.
Frontal artery, 8, 95.
eminences, 5.
lymphatics, 10.
sinuses, 5.
veins, 9.
Function of the cerebellum, 49.
Furrows of the brain, 25.

G.

Galea capitis, 11.
Galen, veins of, 52.
Ganglia, intra-cardiac, 287.
sympathetic, in the thorax, 319.
Ganglion, Arnold’s, 204.
cardiac, of Wrisberg, 285.
ciliary, 94.
diaphragmatic, 322.
Gasserian, 41, 142.
in relation to the circumflex
nerve of the shoulder, 346.
inferior cervical, of the sympa-
thetic nerve, 220.
jugular, 205.
Meckel’s, 69, 142.
middle cervical, of the sympa-
thetic nerve, 219, 233.
of Andersch, 205, 219.
otic, 144.
petrosal, 205.
spheno-palatine, 69, 142.
spiral, 78.
submaxillary, 169.
superior, of the
nerve, 219.
Ganglionic arteries, 23.
Genu of the corpus callosum, 57.
Glabella, 5.
Gladiolus, or mesosternuin, 246.
Gland or glands :
axillary, in relation to cancer,
251.
bronchial, 271.
buceal, 149,
ceruminous, 64.
Jabial, 149.
lachrymal, 83.
lymphatic, at the elbow, 369.

sympathetic

*

 

INDEX.

Gland or glands:
lymphatic, of the axilla, 346.
mammary, 250.
lobes of, 250.
milk-ducts of, 250.
Meibomian, 83.
molar, 149.
palatine, 157.
pineal, 51.
pulmonary lymphatic, 271.
sebaceous, 83.
sublingual salivary, 164.
submaxillary salivary, 164, 199.
sub-sternal, 251,
sweat-, of the hand, 411.
thymus, 223, 240, 260.
tracheal, 237.
Glandulz concatenate, 227.
Glaserian fissure, 66.
Glosso-pharyngeal nerve, distribu-
tion of, 167.
origin of, 43.
Glottis, 179.
respiratory area of, 180.
vocal area of, 180.
Groove, auriculo-ventricular, 276,
bicipital, production of, 361.
for the ulnar nerve, 359, 369.
interauricular, 276.
interventricular, 276.
musculo-spiral, 351.
primitive dental, 151.
Gums, 150.
Gyri operti, 32.
Gyrus fornicatus, 57.

H.

Hematoblasts, 301.
Hemoglobin of the blood, 300.
Hairs, auditory, 75.
of the scalp, 8.
over the back of the hand, 408,
Hand, cutaneous nerve-supply of, 417.
heel of, 409.
hollow of, 409.
median portion of, or metacarpus,
396.
palm of, 409.
region of, 396.
surface-markings of, 406.
Hard palate, 147.
Head, bones of, 2.
development of, 1, 3.
landmarks of, 1.
region of, 1.
surface-form of, 1.
Heart, 275.
54

 

425

Heart, anomalous condition of, 289.
anterior surface of, 275.
area of greatest dulness, 310.
development of, 305.
dimensions of, 277.
fibrous skeleton of, 284.
foetal, 303.
location of apex of, 310.
lymphatic vessels of, 287.
nerves of, 285.
position of apex of, 308.
of base of, 308.
within the thorax, 275.
shape of, 275.
sounds, 306,
propagation of, 307.
reduplication of, 307.
structure of, 284.
within the thorax, examination
of, 309.
Helicotrema, 73.
Helix, 61.
fossa of, 61.
Hemispheres of cerebellum, 47.
of cerebrum, 26.
Hernia, diaphragmatic, 322.

| Herophili, torcular, 18.

Hiatus Fallopii, 69.
semilunaris, 351, 359.

Highmore, antrum of, 133, 144.

Hippocampus major, 52, 57.
minor, 55.

Hollow formed by the extensor mus-

cles of the thumb, 408.
of the armpit, 338.
of the hand, 409.

Horner’s muscle, 85.

-Horny band of Tarinus, 54.

Huguier, canal of, 71.

Humerus, anatomical neck of, 332.
bicipital groove of, 332,
epicondyles of, 348, 365.

Hyaloid membrane, 103.

Hypoglossal nerve, 167.

I.

Impression, subclavian, 255, 325.
Incisura, 61.
Incus, 67.
Infundibula of the lungs, 269.
Infundibulum at the base of the
brain, 39.

of the nose, 5, 113.

or conus arteriosus, 279.
Inion, 6.
Insula, 29.
Intercarotic body, 203.
426

Internal ear, or labyrinth, 60.
Intumescentia gangliformis, 69.
Iris, 99.

pigment-cells of, 100.
Isthmus faucium, 170.
Iter » tertio ad quartum ventricu-

lum, 50.
anterius, 66.
posterius, 66.

Jj.

Jadelot’s lines, 117.
Jaw, ramus of, 139.
Joint or joints:
between the metacarpal bone of
the thumb and the trapezium,
401.
between the pisiform and cunei-
form bones, 398.
carpal and metacarpal, 401.
claviculo-acromial, 324.
costo-vertebral, 241,
elbow-, 363.
enarthrodial, 332.
ginglymus, 363.
inferior radio-ulnar, 375.
interearpal, 397.
interphalangeal, 402.
knuckle, 404.
metacarpal, 402.
metacarpo-phalangeal, 402, 410.
radio-carpal, or wrist-, 397.
shoulder-, 332.
sterno-clavicular, 324.
superior radio-ulnar, 364.
temporo-maxillary, 136.
movements of, 137.

L.

Labia cerebri, 58.
Labium tympanicum, 74,
vestibulare, 74.
Labyrinth, or internal ear, 60, 72.

membranous, 74.

vestibule of, 72.
Lachrymal canal, 113.

fossa, 80.

nerve, 94.

sac, 86, 113.
Lacus lachrymalis, 85.
Lambda, 2, 33.

Lamina, anterior limiting, or elastic,

of Bowman, 87.
cinerea, 37.
cribrosa, 78, 96.
fusca, 97.

 

INDEX.

Lamina ossea, 73.
posterior elastic, of Descemet,
87,
' reticularis, 77.
spiralis, 73.
vitrea, 99.
Larynx, accessory cartilages of fe
male, 179.
arteries of, 184.
cartilages of, 176, 177, 178.
cavity of, 175,
comparison of, in the child and
in the adult, 189.
extrinsic muscles of, 183.
framework of, 176.
intrinsic muscles of, 180.
lodgement of foreign bodies in,
178.
lymphatic vessels of, 186.
mobility of, 186.
nerves of, 185.
region of, 175.
sensibility of, 185.
veins of, 184,
ventricles of, 179.
Lateral tracts, 45.
ventricles, 53.
cornua of, 53.
digital cavities of, 55.
* operation for tapping, 60.
position of, 60.
Lens, capsule of, 102.
crystalline, 102.
function of, 103.
nucleus of, 103.
suspensory ligament of, 102.
Lenticular nucleus, 54.
Leucocytes, 301.
Ligament or ligaments:
anterior and posterior, of elbow-
joint, 364.
and posterior radio-ulnar,
375.
annular, 413.
chondro-sternal, 246.
common spinal, 217.
middle, and posterior costal
transverse, 242.
occipito-atlantic, 217.
of wrist, 398,
auricular, 61.
capsular, of cervical vertebra,
217.
of elbow-joint, 364.
of inferior radio-ulnar joint,
375.
of | metacarpo-phalangeal
joints, 402.

 

Ligament or ligaments :
capsular, of shoulder, 332.
of temporo-maxillary joint,
37.
of wrist, 397.
chondro-xiphoid, 247.
ciliary, 99.
conoid, 325.
coraco-acromial, 330.
coraco-clavicular, 327.
coraco-humeral, 332.
costo-clavicular, or rhomboid,
324.
costo-coracoid, 255,
external and internal, of tem-
poro-maxillary joint, 137.
external lateral, of wrist, 398.
glenoid, of metacarpal phalan-
ges, 402.
of shoulder, 331.
glosso-epiglottic, 178.
hyo-epiglottic, 178.
inferior thyro-arytenoid, or true
vocal cord, 179.
interarticular fibro-cartilagi-
nous, of costo-vertebral joints,
241,
interchondral, 246.
interclavicular, 324.
interlaminar, 213.
internal lateral, of wrist, 398.
interosseous, 375.
interphalangeal, 402.
interspinous, 213.
intrinsic, of auricular cartilages,
63.
lateral metacarpo-phalangeal,
385.
of elbow-joint, 364.
of metacarpo-phalangeal
joints, 402.
metacarpal interosseous, 401.
oblique, 375.
oceipito-odontoid, or check,
217.
of Zinn, 89.
orbicular, 363.
palmar and dorsal intercarpal,
399.
palpebral, 82.
posterior accessory, of costo-
vertebral joints, 241.
annular, 407.
atlanto-axial, 213.
common spinal, 217.
occipito-atlantic, 213, 217,
232.
of wrist, 398.
Ligament or ligaments :
posterior thyro-hyoid, 176.
pterygo-maxillary, 122.
stellate, 241.
sterno-clavicular, 324.
sterno-pericardial, 259.
stylo-hyoid, 165, 172.
stylo-maxillary, 131, 165, 195.
superficial transverse, of the
webs of the fingers, 412.
superior thyro-arytenoid, or false
vocal cord, 179.
supra-condyloid, 379.
suspensory, of axilla, 338.
of axis vertebra, 217.
of the lens, 103.
thyro-epiglottic, 178.
transverse, of axis vertebra, 217.
trapezoid, 325.
Ligamenta lata pulmonalia, 267.
subflava, 213.
suspensoria of the breasts, 250.
Ligamentous action of tendons of
the muscles about the shoulder-
joint, 333.
function of long tendon of biceps
muscle, 352.
Ligamentum arcuatum externum of
the diaphragm, 321.
internum of the diaphragm,
321.
of the wrist, 398.
arteriosum, 305.
latum axiale, 217.
nuche, 209.
pectinatum iridis, 97, 100.
pulmonale, 261.
radiatum, 399.
rectum, 398.
spirale, 74.
* Ligation of brachial artery, 356.
of carotid artery, 226.
of lingual artery, 166.
of radial artery, 391.
of subclavian artery, 231.
of ulnar artery, 393.
Line, labial, 117.
nasal, 117.
oculo-zygomatic, 117.
of axillary artery, 343.
of brachial artery, 356.
of radial artery, 391.
of ulnar artery, 393.
Linea alba cervicalis, 236.
cephalica, 410.
hepatica, 410.
mensalis, 410.
vitalis, 409.

 

INDEX.

Lines of Jadelot, 117.
transverse, over wrist, 406.
Lingula, 47.
Lip, hare-, 156.
Lips, nevi of, 14.9
sensory papillz of, 148.
upper and lower, 148.
vermilion color of, 148.
Liquor Cotunnii, 74.
Morgagni, 103.
_ sanguinis, 291.
Scarpa, 74.
Lobe or lobes:
anterior, or frontal, of the brain,
26, 30.
central, of the brain, 26, 32.
middle, or temporo-sphenoidal,
of the brain, 26.
of the cerebellum, 47.
of the parotid gland, 134.
opercular, 31.
area of, 35.
parietal, of the brain, 26, 30.
posterior, or occipital, of the
brain, 26, 31.
temporal, of the brain, 32.
Lobule or lobules:
crescentic, 47.
cuneiform, 47.
cuneus, 31.
digastric, 47.
infracentral, 31.
marginal, 47.
of the cerebellum, 47.
of the ear, 61.
of the parotid gland, 131.
paracentral, 31.
pulmonary, 269.
quadrate, or preecuneus, 31.
quadrilateral, of the cerebellum,
47.
tonsil, of the cerebellum, 47.
Lobulus gracilis, 47.
Locus cceruleus, 50.
niger, 39.
Lower level of the cerebrum, 33.
Lower, tubercle of, 279.
Lungs, 263.
apex and base of, 263.
degree of their expansion, 264.
elastic tissue of, 269.
great fissure of, 267.
height of, upon right and left
side at root of neck, 262.
limitations of their’ expansion,
265.
lobes of, 267.
lobules of, 269.

 

427

Lungs, mode of detection of degree
of their expansion, 312.
observations on the approxima-
tion of their anterior edges,
264.
cedema of, 270.
previous to birth, 305.
roots of, 267.
spongy texture of, in medico-
legal investigations, 270.
structure of, 269.
Lympbh-paths, 301.
Lymph-space, great cerebral, 23.
Lymphatic duct, 227.
gland or glands:
above the internal epicon-
dyle, 369.
at the back of the pharynx,
175,
deep cervical, 227.
extra-parotid, 133.
in relation to the posterior
border of the sterno-mas-
toid muscle, 206.
in the submaxillary tri-
angle, 199. :
intra-parotid, 133.
of the axilla, 346.
of the lung, 271.
posterior mediastinal, 313.
pulmonary, 271.
sub-sternal, 259.
superficial, of the neck, 193.
jugular trunk, 227.
vessels, frontal, 10.
in relation to the larger
arteries and veins, 299.
occipital, 10.
of the breast, 251.
of the face, 125.
of the fingersand hands, 417.
of the heart, 287.
of the larynx, 186.
of the nose, 111.
of the pharynx, 175.
of the scalp, 10.
of the tongue, 170.
of the tonsil, 171.
parietal, 10.
pulmonary, 271.
Lymphoid tissue of the tongue, 163.
Lyra, 53.

M.

Macula cribrosa, 72.
lutea, 105.
Magendie, foramen of, 50. +
428

Malleus, 67.
‘Mammary glands, 250.
development of, in the male,
251.
supernumerary, in the female,
251.
Manubrium, or presternum, 246.
Margo acutus, 277.
obtusus, 277.
Mastoid antrum, 6.
cells, 6.
foramen, 6.
processes, 6.
vein, 9.
Matrix of the nails, 417.
Meatus, internal auditory, 78.
Meatuses, nasal, 111.
Meckel’s ganglion, 69, 142.
Mediastinum, anterior, 197, 259.
posterior, 263, 312.
superior, 236, 260, 318.
Medulla oblongata, 44.
Medullary capillaries, 24.
velum, posterior, 49.
superior, 49,
Membrana basilaris, 73.
limitans, external and internal,
of the retina, 106.
pupillaris, 101.
sacciformis, 375.
tectoria, 74.
tympani, 65.
secundaria, 67.
Membrane, costo-coracoid, 255, 338.
hyaloid, 103.
interosseous, 375.
mucous, of the nose, 115.
of Reissner, 74.
pituitary, 113.
supra-choroid, 97.
synovial, of elbow-joint, 365.
of shoulder-joint, 334.
of wrist-joint, 397.
thyro-hyoid, 176.
Meningeal arteries, 17.
Metacarpal bones, 399.
Metacarpus, 396.
Middle ear, or tympanum, 60.
thyroid veins, 203.
Mitral regurgitation, 308.
valve, 308.
Moderator, 281.
Modiolus, 73.
Monro, foramen of, 51.
Monticulus cerebelli, 47.
Morgagni, sinus of, 172.
Motor area of the brain, 35.
of the brain-surface, 27.

 

INDEX.

Motor cells, position of, in the gray
matter of the brain, 35.
nerves of the face, 128.
oculi nerve, 91.
Mouth, angles or corners of, 148.
cavity of, 156.
formation of, in the foetus, 156.
region of, 148.
roof of, 156.
vestibule of, 149.
Musce volitantes, 105.
Muscle or muscles :
abductor minimi digiti, 405.
pollicis, 404,
anconeus, 387.
antitragicus, 63.
aryteznoideus, 178.
aryteno-epiglottic, 183.
arytenoid, 183.
auricular, 61.
azygos, 158.
biceps, 351.
function of, 352.
ligamentous function of long
tendon of, 352.
vessels and nerves in rela-
tion to tendon of, 368.
biventer cervicis, 209.
brachialis anticus, 353.
buccinator, 121.
cervicalis ascendens, 212.
ciliary, 99.
circular ciliary, 99.
complexus, 209.
compressor naris, 110.
sacculi, 183.
sacculi laryngis, 179.
coraco-brachialis, 352.
corrugator, 80.
superciliary, 82.
deltoid, 334.
insertion of, 335.
depressor anguli oris, 120.
depressores alarum nasi, 110.
labii inferioris, 121.
digastric, 199. ’
action of, 200.
dilatator pupille, 100.
dilatators of the nose, 110.
extensor carpi radialis brevior,
385.
carpi radialis longior, 384.
carpi ulnaris, 386.
communis digitorum, 385.
indicis, 388.
minimi digiti, 386, 388.
of the thumb, 387.
ossis metacarpi pollicis, 288.

 

Muscle or muscles:
extensor primi internodii polli.
cis, 388,
external intercostal, 256.
rectus, 89,
extrinsic, of the larynx, 183.
flexor brevis minimi digiti, 405.
brevis pollicis, 404.
carpi radialis, 380.
carpi ulnaris, 380,
longus pollicis, 383.
profundus digitorum, 383.
sublimis digitorum, 381.
genio-hyo-glossi, 164.
genio-hyoid, 165.
helicis major, 63.
minor, 63.
hyo-glossi, 164.
-inferior constrictor, 172.
oblique, 91.
_ rectus, 89.
infra-spinatus, 328,
internal intercostal, 256.
rectus, 89.
interosseous, palmar and dorsal,
402.
interspinales, 212.
intertransversales, 212, 219.
intrinsic, of the larynx, 180.
lateral crico-arytenoid, 183.
latissimus dorsi, 329.
laughing, of Santorini, 120.
levator anguli oris, 120.
scapule, 208.
corporis thyroidei, 234.
levatores and tensores palati,
* division of, 159.
labii superioris et alarum
nasi, 120.
labii superioris proprius,
120. "
menti, 121.
palati, 158.
* division of, 158.
palpebrarum, 82.
uvule, 158.
linguales, 163.
long tendon of biveps, 333.
Jongus colli, 218.
lumbricales, 403.
masseter, 122.
middle constrictor, 172.
‘multifidus sping, 212.
mylo-hyoid, 163, 165.
oblique auricular, 63.
obliquus capitis inferior, 212,
‘occipito-frontalis, 11.
of ball of little finger, 405.
Muscle or muscles :
of ball of thumb, 404.
of crico-thyroid, 180.
of expression, 119.
of face, 119,
of forearm, 379.
of nose, 109.
of orbit, action of, 92.
paralysis of, 92.
omo-hyoid, 195, 200.
opponens minimi digitis, 406.
pollicis, 404.
orbicularis, 81.
oris, 119.
palpebrarum, 82.
palato-glossi, 159, 164.
palato-pharyngei, 159.
palmaris brevis, 411.
longus, 380.
pectoral accessory, 255.
pectoralis major, 253.
elavicular portion of,
253.
cleft between its two
portions, 254.
sternal portion of, 254.
minor, 255.
platysma myoides, 191.
posterior crico-arytenoid, 181.
pronator quadratus, 384.
radii teres, 379.
teres, 393.
pterygoid, external, 138.
internal, 138.
pyramidales nasi, 109.
rectus capitis anticus major, 218.
capitis anticus minor, 218.
capitis lateralis, 218.
capitis posticus major, 212.
capitis posticus minor, 212.
rhomboideus, major and minor,
329.
risorius, 121, 181, 191.
salpingo-pharyngeus, 159.
sealenus anticus, 220.
guide for subclavian
artery, 229.
medius, 220.
posticus, 220.
serratus magnus, 331.
sphineter colli, 191.
pupilla, 100.
spinalis colli, 212.
splenius, 207.
stapedius, 68.
sterno-cleido-mastoid, 197.
sterno-hyoid, 235.
sterno-mastoid, action of, 198.

 

INDEX.

Muscle or muscles:
sterno-thyroid, 235.
stylo-glossi, 164.
stylo-hyoid, 199.
stylo-pharyngeus, 172.
sub-anconeus, 354.
subclavian, 256.
sub-scapularis, 330.
superior constrictor, 172.

oblique, 91.

rectus, 89.
supinator radii brevis, 387.

radii longus, 384.
supra-hyoid, 200.
supra-spinatus, 328.
temporal, 14, 136.
tensor tarsi, 85.

tympani, 68.
tensores or circumflexi palati,

158.

palati, division of, 159.
teres major, 328,

minor, 328.
thyro-arytenoid, 181.
thyro-epiglottic, 181.
thyro-hyoid, 236.
trachelo-mastoid, 209.
tragicus, 63.
transversalis colli, 209.
transverse auricular, 63.
trapezius, action of, 209.

cervical portion of, 208.
triangularis sterni, 257.
triceps extensor cubiti, 353.
trochlearis, 91.
zygomaticus major, 120.

minor, 120.

Muscular fibres of the heart, infer-
ences drawn as to their
function, 285.

superficial and deep layers
of, 284.

Musculi papillares, 281.
pectinati, 279, 283.

Musculo-spiral groove, 351,

N.

Nail-bed, 419.

Nails, 417.
growth of, 417,
lunula of, 417.
matrix of, 417.
peculiarities of, 417.
root of, 417.

Nares, anterior and posterior, 111,

114.
Nasal artery, 95.

 

Nasal bones, 107.
cavities, arteries of, 115.
veins of, 115.
duet, 80, 113.
fossee or cavities, 111.
dimensions of, 113,
walls of, 111.
meatuses, 111.
nerve, 93.
veins, 110.
Nasion, 5, 107.
Nates, 50.
Neck, anterior triangle of, 198.
deep fascia of, 193.
development of, 190.
landmarks of, 187, 189.
posterior triangle of, 193.
region of, 187.
skeleton of, 187.
skin over front of, 191.
over nape of, 191.
structures collected at root of,
221.
superficial glands of, 193.
Nerve or nerves:
abducent, 41, 92.
acromial, 193.
anga hypoglossi, 205.
anterior branch of internal cu-
taneous, 378,
branch of musculo-cuta-
neous, 378,
division of external cuta-
neous of musculo-spiral,
378.
interosseous, 393.
palatine, 115.
articular, to elbow-joint, 393.
auditory, 41, 77.
auricular, Arnold’s, 204.
branch of pneumogastric, 11.
auricularis magnus, 192.
auriculo-temporal, 11, 128, 143.
axillary or brachia? plexus, 344.
brachial, plexus of, in relation
to subclavian artery and
veins, 229,
branches of fifth cranial, 41.
buecal, motor, 128.
sensory, 128.
cardiac, 288.
cells, 25,
cervical plexus, 193.
spinal, 214.
ganglia of, 214.
roots of, 214.
cervico-facial, 129.
chorda tympani, 69, 143.
430

Nerve or nerves:

chorda tympani, supposed fune-
tion of, 71.
circumflex, 334, 346.
clavicular, 193.
cochlear, 78.
communicantes, 207. .
communicating filaments of, in
the forearm, 394.
course and relations of left pneu-
mogastric, 318.
of right pneumogastric, 317.
cutaneous palmar branch, 393.
deep cervical plexus, 206.
palmar branch of ulnar,
415.
descendens hypoglossi, 167, 205.
digital, 416.
distribution of various digital
cutaneous, 417.
dorsal branch of ulnar, 378.
eighth cranial, 41.
eleventh cranial, 43.
external anterior thoracic, 346.
cutaneous, 349.
of musculo-spiral, 378.
laryngeal, 185.
palmar of median, 416.
superficial petrosal, 69.
facial, 41, 69, 129.
communications of, 71.
fibres, 25.
fifth cranial, 40.
first cranial, 38.
spinal, 213.
fourth cranial, 40.
from otic ganglion, 144.
frontal, 93.
glosso-pharyngeal, 43, 134, 169,
205.
ganglia of, 205.
great auricular, 63, 129.
occipital, 11, 193, 213, 214.
splanchnic, 320.
groove for ulnar, 348.
hypoglossal, 44, 134, 167, 265.
incisor, 143.
inferior cardiac, 220.
dental, 143.
laryngeal, explanation of its
recurrent course, 186.
maxillary, 41, 142.
or recurrent laryngeal, 185,
infra-maxillary, 130.
infra-orbital, 145.
infra-trochlear, 93.
intercosto-humeral, 339, 360.
internal anterior thoracic, 346.

 

INDEX.

Nerve or nerves:

internal cutaneous, 359.
laryngeal, 185.
palmar of median, 416.
interosseous, 392.
labial, 127.
lachrymal, 9-.
lesser: internal cutaneous, of
Wrisberg, 360.
splanchnic, 320.
lingual, 143.
* division of, 169.
* position for division of, in
cancer of the tongue, 144.
long ciliary, 93.
sub-scapular, 346.
median, 351, 356, 357.
at the elbow, 368.
in relation to the anterior
annular ligament, 416.
in the forearm, 393.
mental, 128, 143.
middle cardiac, 219.
motor, buecal, 130.
malar, 129,
oculi, 91.
of face, 128.
of masseter muscle, 123.
to pterygoid muscles, 138.
muscular branches of median in
the forearm, 393.
of brachial plexus, 345.
musculo-cutaneous, 352, 357.
musculo-spiral, 354, 360.
in the forearm, 394.
liability of, to injury in con-
tusion or fractures, 361.
mylo-hyoid, 143, 199.
nasal, 93.
from the spheno-palatine
ganglia, 115.
of infra-orbital, 127.
of ophthalmic, 115.
aso-lobular, 110.
naso-palatine, 115.
ninth cranial, 43.
oculo-motor, 39.
cesophageal, 317.
of Lancisi, 57.
of the axillary folds, 339.
of the breast, 251.
of the cornea, 88.
of the dura mater, 19.
of the heart, 285.
of the iris, 101.
of the larynx, 185.
of the nose, 110.
of the pericardium, 274.

 

Nerve or nerves:

of the pinna, 63.
of the scalp, 10.
of Wrisherg, 71.
olfactory, 38, 116.
ophthalmic, 41.
paralysis of, 94,
optic, 38, 95.
passage of, through the
sclerotic coat, 96.
orbital branch of superior max-
illary, 11.
palatine, 161.
palpebral, 127.
pharyngeal, 204.
plexus of, 175, 204.
phrenic, 221, 268, 322, 345.
plexus, posterior cervical, 214.
pneumogastric, 43, 134, 204, 222,
225.
branches of, 204.
communicating branches of,
with the brachial plexus,
205.
ganglion of the root, 204.
of the trunk, 204.
pulmonary plexuses of. 267.
within the thorax, 317.
posterior auricular branch of
facial, 11, 63.
branch of internal cuta-
neous, 378.
branch of muscular cuta-
neous, 378.
dental, 145.
division of external cuta-
neous of musculo-spiral,
378.
external cutaneous, 360.
internal cutaneous, 360,
interosseous, 394.
lateral cutaneous, 339.
thoracic or external re-
spiratory of Bell, 345.
ulnar cutaneous, 394.
pulmonary, 271.
radial, 391, 394, 408.
where it becomes superficial
in the forearm, 378.
recurrent laryngeal, 226, 268.
second cranial, 38.
sensory, of nose, 115.
of orbit, 93.
seventh cranial, 41.
sixth cranial, 41.
small occipital, 11, 193.
petrosal, 69, 144,
smaller splanchnic, 320.
Nerve or nerves:
spinal accessory, 44, 134, 198,
205.
accessory portion of, 206.
spinal portion of, 206.
splanchnic, 319.
splenic, 207.
sternal, 193.
sterno-mastoid, 207.
subcutaneus mala, 127.
sub-occipital, 214.
posterior division of, 213.
sub-scapular, 346.
superficial cervical, 130, 192.
over parotid region,
133.
palmar, 416.
superior cardiac, 219.
laryngeal, 185, 204.
maxillary, 127, 142.
supra-clavicular, 229.
supra-maxillary, 130.
supra-orbital, 10, 94.
supra-scapular, 330, 345.
supra-trochlear, 10, 93.
sympathetic, cervical portion of,
219.
in the neck, 195.
temporo-facial, 129.
temporo-malar, 127.
tenth cranial, 43.
third cranial, 39.
to tensor palati muscle, 161.
triangles of, 198.
trifacial, 41.
trochlear, 40, 92.
twelfth cranial, 44.
tympanic branch of the facial,
69.
ulnar, 359, 392, 393, 409.
at elbow, 369.
in relation to the anterior
annular ligament, 415.
vagus, 43.
vaso-constrictor, 300.
vaso-dilator, 300.
vaso-motor, 299.
about facial artery, 124.
of iris, 102.
vestibular, 78.
Vidian, 69, 141, 142.
Nipple, relative position of, 250,
Nipple-line unreliable, 311.
Nipples, 250.
Nodi valvulz mitralis, 283.
Nodulus of the cerebellum, 47.
Nose, arteries of, 110.
cartilaginous framework of, 108.

 

INDEX.

Nose, lobule of, 110.
lymphatic vessels of, 111.
nerves of, 110.
region of, 107.
skeleton of, 107.

Nostrils, exploration of, 114.

Notch, great, of scapula, 331.

_of Rivinus, 65.

sigmoid, 136.
supra-orbital, 5.
supra-scapular, 233, 330.
supra-sternal, 246.
thyroid, 176.

Nuclei laterales, 46.

Nucleus amygdala, 54.
caudate, 54.
gracilis, 46.
lenticular, 54.
of fibro-cartilage, 215.
of lens, 103.
olivary, 45.

oO.

Obelion, 6.

Obex, 50.

Oblongata, medulla, 44,

Occipital artery, 8.
lymphatics, 10.
veins, 9.

Oculo-motor nerves, origin of, 39.

Odontoblasts, 153.

* Hisophagotomy, operation of, 315.

Csophagus, 315.
arteries of, 317.
at the root of the neck, 268,
coats of, 317.
constrictions of, 315.
diameter of, 316.
lateral curves of, 316.
relations of, to the vertebral col-

umn, 315.

Olecranon process, 362.

Olfactory bulbs, 38.
cells, 114.

Olivary bodies, 45.
nucleus, 45.

Opening, auriculo-ventricular, 278.
left auricuto-ventricular, 283.
right auriculo-ventricular, 279.

* Operation of trephining for tapping

lateral ventricles, 60.

Opercular lobe, area of, 35.

Operculum, 29.

Ophryon, 5, 35.

Ophthalmic artery, 94.
ganglion, 94.
veins, 95.

Optic commissure, 38.

 

431

Optic foramina, 38.
lobes, 50.
nerve, 95.
nerves, origin of, 38.
papilla, 105.
thalami, 52.
function of, 59.
tracts, 38.
Ora serrata, 105.
Orbit, sensory nerves of, 93.
Orbital region, 79.
Orbits, bones forming, 80.
walls of, 79.
Organ of Corti, 74.
Os cordis, 284,
Ossicles, 65, 67.
Ossification of the bone of the arm,
361.
of the bones of the forearm, 396.
of the bones of the hand, 418.
of the bones of the wrist, 418.
Otic ganglion, 144,
Otoliths, 75.

P.

Pacchionian bodies, 16.
depressions, 15.
Pacinian corpuscles, 417.
Palate, arteries of, 159.
cleft, in association with hare-
lip, 148.
cleft of, 156.
closure of, 156.
hard, 147, 156.
muco-periosteal
157.
pillars of, anterior and posterior,
157.
raphé of, 157.
soft, 157.

covering of,

| Palm of the hand, 409.

subcutaneous tissue of, 411.
Palmar arch, deep arterial, 415.
posterior, 392.

superficial arterial, 414.
fascia, 411.
development of, 412.
expansions of, 412.
Papilla spiralis acoustica, 77.
Papille circumvallate, 161.
filiform, 162.
fungiformes, 162.
of the eyelids, 85.
of the hand, 411.
sensitive, of the nipple, 250.
sensory, of the lips, 148.
Parietal lymphatics, 10.
432

Parotid fascia, 130.
gland, deep surface of, 134.
dissection of, 135.
extirpation of, 135,
lobes of, 134.
region of, 130.
relations of, 131.
Pars ciliaris, 105.
intermedia of Wrisberg, 41.
Passage, cervico-axillary, 339.
Peduncles of the cerebellum, 49.
of the pineal gland, 51.
Pericardium, 271.
attachment to the diaphragm,
273.
invagination of the serous layer
over the vessels at the root of
the heart, 274.
layers of, 274.
nutrient arteries of, 274.
serous fluid within, 274.
Perichondrium over the nasal carti-
lages, 109.
Pericranium, 13.
Perilymph, 74.
Pes accessorius, 55.
anserinus, 129, 135,
cervicis, 193.
hippocampi, 52, 57.
Petit, canal of, 103.
Phalanges, 396, 401.
proximal, medial, and distal, 401.
ungual, 401.
Pharyngeal recess, 173.
tonsils, 173.
Pharynx, 171.
arteries of, 175.
naso-, 173.
oro-, 173.
Phrenic arteries, 322.
Pia mater, 21.
Pineal gland, 51.
Pinna, 60.
arteries of, 63.
nerves of, 63.
veins of, 63.
Piso-cuneiform joint, 398.
Pituitary body, 39.
Plasma, 301.
Pleura, cavity of, 261.
* operation of tapping, 261.
costalis, 261.
parietal layer of, 261.
pulmonis, 261.
visceral layer of, 261.
Pleurm, 260.
height upon right and left side
at the root of the neck, 262.

 

INDEX.

Pleurez, limitations of their reflec-
tions, 262.

Pleural sinuses, 252,

Plexus, diaphragmatic, 322.
cesophageal, 318.
pterygoid, 141.
radial dorsal of hand, 408.
supra-renal, 322.
tonsillar, 171.
ulnar dorsal of hand, 408.

Plexuses, cardiac, 285.
choroid, 23, 52.
coronary, 287.
pulmonary, 285, 318.

Plica interdigitalis, 411.
semilunaris, 85.

Pneumogastric nerve, auricular

branch of, 11.
in the neck, 204.
origin of, 43.
nerves within the thorax, 317.

Pomum Adami, 176, 189.

Pons Varolii, 46.

Portio dura, 41.
mollis, 42.

Porus opticus, 96, 105.

Posterior auricular artery, 8.

veins, 9.
nares, 114.

Process, acromion, 330.
coracoid, 330.
coronoid, of lower jaw, 136, 150.

of ulna, 362.
ensiform, or metasternum, 246.
external angular, of orbits, 5,

80.

hamular, of sphenoid bones, 158.
malar, 145.
nasal, 145.
olecranon, 362.

in relation to epicondyle of

humerus, 367.

olivary, of sphenoid bone, 38.
palate, 145, 147.
styloid, 169.
supra-condyloid, 351.

Processes, alveolar, 145.
ciliary, 99.
mastoid, 6.
nasal, of superior

bones, 108.
transverse, of dorsal vertebrae,
242.
ungual, 402.

Processus cochleariformis, 67.

e cerebello ad testes, 49.
unciformis, of brain, 32.
Promontory, 66.

maxillary

 

Protuberance, external occipital, 6.
Pterion, 2, 33.
Pulmonary capillaries, 270.
emphysema, 270.
veins, 270.
Pulps of the fingers, 411.
Pulse, arterial, 307.
respiratory, 307.
Pulse-area, 391.
Pulvinar of the brain, 52.
of the larynx, 179.
Puncta lachrymalia, 82.
of the eyelids, 85.
vasculosa, 58,
Punctum cecum, 105.
Pupil, 100.
muscular fibres of, 100.
size of, 100. :
Pyramid, anterior, of the tympanum,
67.
Pyramidal tract, 58.
Pyramids, anterior, of the medulla,
45.
posterior, of the medulla, 45.

R.

Radial artery, 389.
branches of, in the forearm,
389.
ligation of, 391.
line of reference of, 391.
venz comites of, 389.
Radiatio thalami, 59.
Radius, anterior crest of, 373.
articular surface of lower end
of, 393.
carpal articular surface of, 373.
fracture of lower end of, 395.
head of, 363.
interosseous edge of, 373.
lower end of, cancellous struc-
ture of, 395.
extremity of, 373.
neck of, 363.
ossification of, 396.
shaft of, 373.
styloid process of, 373.
tubercle of, 363.
ulnar depression of, 373.
Raphé of corpus callosum, 57.
posterior, of pharynx, 172.
Recess, pharyngeal, 173.
Region of the arm, 348.
of the axilla, 337.
of the ear, 60.
of the elbow, 362.
of the face, 116.
Region of the forearm, 372.
of the hand, 396.
of the head, 1.
of the larynx, 175.
of the mouth, 148.
of the neck, 187.
deep fascia of, 193.
of the nose and the nasal cavi-
ties, 107.
of the orbit and the eye, 79.
of the parotid gland, 130.
of the shoulder, 323.
of the thorax, 240.
of the wrist, 396.
pterygo-maxillary, 136.
superior maxillary, 144.
Reil, island of, 32.
Reissner, membrane of, 74.
Restiform bodies, 45.
Rete acromiale, 341.
carpi, 415.
anterior and posterior, 389,
392.
mirabile, 299.
neural, anterior and poste-
rior, 315.
nasi, 115.
olecrani, 355, 370, 392.
Retina, 105.
central artery of, and vein, 96.
ganglionic cells of, 106.
hyaloid surface of, 105.
layers of, 106.
rods and cones of, 106.
Rib, angle of, 242.
anomalous eighth true, 241.
body or shaft of, 242.
eleventh and twelfth, 245.
first, 243.
neck of, 242.
occasional rudimental thirteenth,
245.
second, 43.
spiral shape of, 243.
tenth, 243.
tuberosity of, 242.
Ribs, 240.
false or asternal, 241.
floating, 241.
fractures of, 245.
mode of counting, 310.
obliquity of, 240, 248.
relation in respiration, 309.
true or sternal, 241.
vertebral extremities of, 241.
Rictus oculi, 81.
Ridge between the manubrium and
gladiolus of the sternum, 245, 310.

 

INDEX.

Ridges, deltoid, 335.
superciliary, 5.
supra-condyloid, 348,
temporal, 5.

Rima glottidis, 180,

Rivinus, ducts of, 164.
notch of, 65.

Rolando, fissure of, 27.

Rostrum of corpus callosum, 57.

Ss.

Sac, lachrymal, 86.

Saccule, 75.

Sacculus laryngis of Morgagni, 179.

Saliva, 131.

Santorini, cartilages of, 178.

Scala media, 73.

tympani, 73.
vestibuli, 73.
Scalp, 7.
aponeurosis of, 13.
arteries of, 8.
cutaneous muscle of, 11.
lymphatic vessels of, 10.
nerves of, 10.
veins of, 9.
Scalp-hairs, 8.
Scapula, 328.
borders of, 328.
bursze in connection with, 329.
glenoid cavity over, 331.
head of, 331.
inferior angle of, 329.
neck of, 331.
proper situation of, in relation
to the skeleton, 328.
*removal of, 342.
spine of, 328.
sub-scapular fossa or venter, 330.
superior and inferior spinous
fossee of, 328,

Scarpa, foramen of, 147.

Schneiderian membrane, 113.

Sclerotic coat, 88.

Sella turcica, 39.

Semilunar fold of the bicipital fascia,
352.

Semilunaris, hiatus, 359.

Sensitive area of the finger-tips, 417.

Sensorial area of the brain, 36.

Sensory nerves of the face, 125.

Septum lucidum, 53.

Serum, 301.

Sesamoid bones at the metacarpo-
phalangeal joint of the thumb,
402.

Shaft, humero-ulnar, 376.

55

 

433

Sheath, sub-sternal tubular, 259,
Sheaths, tubular, of the pericardium,
274,
Shoulder, * dislocations of, 336.
* fractures of, 337.
girdle, 323.
region of, 323.
Shoulder-joint, 332.
*amputation of, 337, 344.
arteries of, 334.
bursz connected with, 334.
motions of, 334,
nerves of, 334,
Sigmoid cavity, greater, 362.
lesser, 363.
Sinus circularis iridis, 96.
coronary, 277.
entrance of, 279.
great oblique, of the pericardium,
274,
jugular, 203.
maximus, 288,
of Morgagni, 172. .
of Valsalva, 277, 284.
pulmonary, of Valsalva, 282.
superior longitudinal, 18.
transverse, of the pericardium,
274,
venosus, 278.
Sinuses, cavernous, 19, 125.
frontal, 5.
lateral, of the dura mater, 18,
maxillary, 144.
of the dura mater, 18, 296.
petrosal, 18.
pleural, 262.
Skin covering the auricle, 61.
of the axilla, 338.
of the eyelids, 81.
over the anterior surface of the
thorax, 249.
over the arm, 349.
over the back of the band, 408.
over the elbow, 367.
over the forearm, 377.
over the neck, 190.
over the nose, 109.
over the shoulder, 323.
over the temporal region, 14,
over the wrist, 406.
Skull-cap, inequality of its thick-
ness, 14.
Space, crico-thyroid, in children, 184,
interosseous, 376.
importance of preservation
of, in the treatment of
fractures of the forearm,
376.
434

Space, interpleural, 263.
occupied by parotid gland, 131.
perineural, of eyeball, 91.
sub-dural, 21.
Spaces, anterior perforated, 22, 38.
intercostal, 247, 313.
of Fontana, 97, 102.
posterior perforated, 22, 39,
sub-arachnoidean, 44.
Speculum rhomboideum, 208..-
Speech-centre, 30.
Spinal accessory nerve, origin of, 43.
column, weakest point of, 218.
Spine, cervical curve of, 218,
curvature of cervical portion of,
215.
Splenium of corpus callosum, 57.
Spot for reflex contraction of masseter
muscle, 123.
Stapes, 67.
Stenson, duct of, 131.
opening of, 149,
foramen of, 147.
Stephanion, 6.
superior, 35.
Sterno-mastoid muscle, 206.
Sternum, 246.
differences in the male and the
female, 247.
inclination of middle line of,
247.
Strix acoustics, 50.
lateral, 57.
longitudinal, 57.
transverse, of fourth ventricle
of the brain, 50.
vascularis, 74.
Subclavian artery, 211.
Subcutaneous tissue of scalp, 7.
Sucking cushions, 117.
Supra-orbital artery, 8.
Surface-markings of the wrist and
hands, 406.
Suture, coronal, 2.
frontal, 2.
interparietal, or sagittal, 2.
lambdoid, 2.
Sutures, 2.
closure of, 3.
dentate, 2.
squamous, 2.
Sweat-glands of the axilla, 338.
Sylvius, aqueduct of, 50.
fissure of, 27.
Sympathetic nerve in the neck, 219.
in the thorax, 319.
plexuses at base of brain,
24,

 

INDEX.

Synovial membrane at elbow-joint,
365.
between the metacarpal
bone of the thumb and
the trapezium, 399.
of the piso-cuneiform joint,
398.
of the shoulder-joint, 334,
of the wrist-joint, 397.
mémbranes in relation to the
extensor tendons on the back
of the hand, 408.
sacs in relation to the anterior
annular ligament, 413.
sheaths in relation to the ten-
dons of the fingers, 413.
sheaths of the fingers in relation
to felon, or whitlow, 413.
Systole of the heart, 277.

‘Ts

Tabatiére anatomique, 388.
Table, vitreous, 15. ~
Tables of the cranial bones, 3.
Tenia hippocampi, 53, 57.
semicircularis, 53.
Tapetum, 105.
nigrum, 106.
Tarinus, horny band of, 54.
Tartar, 150.
Taste-buds, 162.
Tears, 83.
Teeth, 151.
bicuspids or premolars, 153.
canines, 153.
development of, 151.
of the permanent, 152.
function of, 153.
germs of the temporary, 151.
incisors, 153.
molars, 153.
peculiarities of, 155.
periods of eruption, 152,
permanent, 151.
wisdom, 152.
Tegmentum, 39.
Temporal artery, 8.
anterior branch of, 8.
bones, 7.
fascia, 14.
attachment of, 6,
muscle, 14, |
attachment of, 6.
region, 14,
veins, 9.
Tendo oculi, 82.
Tenon, capsule of, 89, 93.

 

Tentorium, 16.
Testes, 50.
Thalamo-lenticular limb, 55.
Theca vertebralis, 214.
Thenar eminence, 409,
Thoracic duct, 227, 318.
Thorax, apertures of, 248,
base of, 249,
landmarks of, 240,
percussion of, 310.
region of, 240.
skeleton of, 240, 247.

“summit of, 249.
surfaces of, 248,
variability in form of, at differs

ent periods of life, 248.
variation of shape, 309.
Thumb, ball of, 404.

‘extensor muscles of, 387.
metacarpal bone of, 401.
movements of, 404,

Thymus gland, 260.
lympbh-follicles of, 260.
probable function of, 260.

Thyroid body, 233,
arteries of, 235.
colloid substance of, 234.
isthmus of, 233.

Jateral lobes of, 233.

pyramidal or middle lobe of, 234.
size of, 234,

supposed function of, 234.

veins of, 235.

Tongue, 161.
dorsum of, 161.
furring of, 161.
hemorrhage in excision of, 166,
intrinsic muscles of, 163.
lymphatic vessels of, 170.
lymphoid tissue of, 163.
median septum of, 163, 166.
root of, 161.
source of its gustatory function,

167.
tip of, 161.

Tongue-tie, relief of, 162.

Tonsils, 170.
nerves of, 171.
pharyngeal, 173,
relations of, 170.
vascularity of, 171.

Tooth, body of, 153.
cement of, 153.
crown of, 153.
dentine, 153.
enamel, 153.
neck of, 153.
pulp of, 153.
Topographical relation of the corpora
striata to the external surface
of the head, 59.
survey of the chest, 308.
Topography, cranio-cerebral, 32.
Torcular Herophili, 18.
Trachea, 235, 236.
arteries of, 237.
at the root of the neck, 268.
cartilaginous rings of, 236, 237.
length of, and dimensions, 236.
mobility of, 237.
*Tracheotomy, operation of, 237-
239.
Tragus, 61.
* Trephining, operation of, in relation
to the fissures of the brain, 37.
Triangle, inferior carotid, 201.
occipital, 206.
submaxillary, or digastric, 199.
sub-occipital, 213.
sub-scapular, 342.
superior carotid, 201.
supra-clavicular, or subclavian,
207.
Triangles of the neck, 198.
Triangular fibro-cartilage, 397.
Tricuspid valve, 307.
Trifacial nerves, origin of, 40.
Trochlea, 91.
Trochlear nerves, origin of, 40.
Tuber cinereum, 38.
Tubercle, bicipital, 352.
carotid, 189.
conoid, 325.
infra-glenoid, 331.
of Lisfrane, 220.
of Lower, 279.
supra-glenoid, 331.
Tuberosity, deltoid, 335.
Tunica Ruyschiana, 97.
Tympanie cavity, 65.
Tympanum, or middle ear, 60, 65.
arteries of, 71.
veins of, 71.
walls of, 67.

U.

Ulna, head of, 375.
interosseous edge of, 375.
ossification of, 396.
shaft of, 373.
styloid process of, 375.
Ulnar artery, 391.
branches of, in the forearm,
391.
line of reference for, 393.

 

INDEX.

Umbilicus of the membrana tympani,
65.

Ungual phalanges, 401.

Utricle, 72, 75.

Uvea, 100.

Uvula, 157.

V.

Vagus nerve, 43,
Vallecula, 27, 38.
Valve or valves:
aortic semilunar, location of, 311.
auriculo-ventricular, flaps of,
281.
bicuspid, or mitral, 283.
coronary, 277.
Eustachian, 303.
mitral, 308.
location of, 311.
of Hasner, 113.
of Thebesius, 279.
of tributary vein to axillary
vein, 344.
of Vieussens, 40, 49.
semilunar, of aorta, 284,
of pulmonary arteries, 282.
location of, 311.
tricuspid, 279.
location of, 311.
safety arrangement of third
flap of, 307.
Varoiii, pons, 46.
Vas aberrans, 352, 355,
spirale, 74.
Vasa vasorum, 299,
Vascular circle of the lips, 124.
Vaso-constrictor nerves, 300.
Vaso-dilator nerves, 300.
Vaso-motor nerves, 299.
Vein or veins:
angular, 125. #
anomalies of, 296.
anterior jugular, 192.
median, 268.
auditory, 78.
axillary, 344.
influence of costo-coracoid
membrane upon, 344,
relation of, to axillary ar-
tery, in different positions
of the arm, 344,
tributaries of, 344,
basilic, 351.
brachial, 369.
brachio-cephalic, 222.
bronchial, 271.
cardiac, 277.
cavernous plexus of, 19.

 

Vein or veins:
cephalic, 349.
cervico-dorsal spinal, 213.
circumflex, 344.
coats of, 297.
common jugular, 203, 225.
communication of, 296.
coronary, 276.
course of, in various localities,
296.

deep facial, 125.

radial, 389.
diploic, 15.
emissary, 9.
ethmoidal, 115.
external jugular, 191.

valves of, 192.
facial, 125, 199, 203.
frontal, 9.
hepatic, 304.
inferior thyroid, 235, 239.
infra-orbital, 145.
innominate, relative position of,
222.

valves of, 223.
internal jugular, 134, 203.

mammary, 223, 259.

maxillary, 141, 192.

larger posterior superficial ulnar,
408.
posterior ulnar, 377.
left innominate, 288.
lingual, 167, 203.
mastoid, 9.
median basilic, 368.
* with reference to vene-
section, 368.
cephalic, 368.
mediastinal, 223.
middle thyroid, 203.
nasal, 110.

peculiarity of, in children,

115.
occipital, 9, 192, 203.
cesophageal, 317.
of the breast, 250.
of the choroid coat, 97.
of the dura mater, 18.
of the forearm, 377.

* importance of recognition
of, in the application of
bandaging, 378.

of the larynx, 179, 184.
of the nasal cavities, 115.
of the pinna, 63.

of the scalp, 9.

of the tympanum, 71.
ophthalmic, 95.
436

Vein or veins:
peculiarities of, in certain organs,
296.
pharyngeal, 203.
plexus of, 175.
plexus of, at root of neck, 223.
portal, 304.
posterior auricular, 9, 192.
pulmonary, 270, 290.
in relation to the pulmonary
arteries, 269, 290.
openings of, 283.
ranine, 167.
relative position to the main
trunks of the arteries, 298.
renal, 222.
scapular, 342,
small superficial anterior ulnar,
377, 408.
structure of walls of, 297.
subclavian, 221.
right and left, 229,
submaxillary, 192, 199.
sub-scapular, 344.
superficial and deep, 296.
at the bend of the elbow,
367.
at the wrist, 407.
communicating, 378.
median, 377.
of the hand, 408.
radial, 377.
superior thyroid, 203.
middle, and inferior thy-
roid, 235.
supra-scapular, 229,
systemic, 296.
temporal, 9.
thymic, 223.
tonsillar, 171.
transversalis colli, 206, 233.
transverse facial, 192.
umbilical, 303.
valves of, 297.
vertebral, 215, 233.

 

INDEX.

Velum interpositum, 23, 51.
pendulum palati, 157.

Vena anastomotica, 368.
azygos major, 267, 319.

minor, 319.
cava inferior, opening of, 278.
cava superior, 222, 287.
opening of, 278.
cephalica pollicis, 408.
salvatella, 408,
Vene comites, 292, 296.
of brachial artery, 357.
of great meningeal artery,
es
of interosseous artery, 392.
of radial artery, 389.
of superficial cervical ar-
tery, 233.
of ulnar artery, 392.
Galeni, 52.
cordis, 279.
innominate, 222.
vorticose, 97.

Venosus ductus, 304.

Ventricle, fifth, of the brain, 53.
fourth, of the brain, 49.
lateral, of the brain, 53.

position of, 60.
left, of the heart, 283.
walls of, 283.
of Arantius, 50.
of corpus callosum, 58.
right, of the heart, 279.
walls of, 278.
third, of the brain, 51.
Vermiform process of the cerebellum,
47,

Vermis, inferior, 47.
superior, 47.

Vertebra, dorsal or thoracic, 248, 249.
prominens, 189.

Vessels, axillary, sheath of, 255.
carotid, sheath of, 225.

position of, 225.
posterior dental, 145.

END OF VOL. I.

 

Vessels, palatine, 147,
supra-scapular, 330.
Vestibule of the mouth, 149.

of the tympanum, 66,
Vibrissee, 111.
Vidian nerve, 142.
Vieussens, valve of, 49.
Vineula above the knuckle-joints,
386.
Vitreous body, 103.
Vocal cord, false, 178.
true, 178.
Voice, change of, 183.

Ww.

Walls of the auditory canal, 64.
of the nasal fosse, 111.
of the orbits, 79.
Wharton, duct of, 165.
Willis, circle of, 22.
Wormian bones, 5.
* Wounds of the palm, 415.
Wrisberg’s nerve, 360.
Wrist, or carpus, 396.
region of, 396.
surface-markings of, 406.
Wrist-joint, 397.
movements of, 398.
synovial membrane of, 397.
Wry-neck, 198, 208.

X.
Xiphoid appendix, 246.

Ne
Yellow spot of the retina, 105.

Zz.

Zinn, ligament of, 89.
Zone of Zinn, 99, 103.
Zygoma, 138.
Srimeneesatzg

Loria