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M o » <./ . ,..tX;O i X'U'>| Descriptive Anatomy 
WM. B. TOWLES, 
Revised and Enlarged 
By W. G. CHRISTIAN, 
Professor of Anatomy in the Medical College 
of Virginia 
Fourth Edition 
Appeals Press 
Richmond, Va. 
1915 COPYRIGHT, 1915, 
BY 
W. G. CHRISTIAN. PREFACE 
Towles' Notes on Anatomy, forms the basis of the present work, 
which is a student's book: it is not intended to imitate those works 
which are designed for practitioners and students alike, the writer 
being certain that such a book never has been and never can be 
written. It has been the intention in this work to give to the stu- 
dent a clear, complete statement of the positive truths of anatomy, 
leaving embryology and histology, so largely treated in other 
works, to the care of the professors of these subjects. The writer 
has discussed neither surgery nor practice of medicine, but de- 
scriptive anatomy, pure and simple, in such a way as the needs of 
the student demand. Every effort has been made to free the book 
from errors. It has been greatly enlarged and, it is believed, will 
now supply all that the student needs. 
W. G. Christian. DESCRIPTIVE ANATOMY. 
OSTEOLOGY. 
The study of the bones which form the human skeleton, indi- 
vidually and in relation to one another, with regard to the ap- 
pearances which they present to the unaided eye, and the uses 
for which they are intended, constitutes Osteology, as pertaining 
to Descriptive Anatomy. The chief uses of bones in the living 
body are: 
1. To give support to the softer tissues. 
2. To form receptacles for important organs. 
3. To form unyielding points of attachment for the muscles. 
4. To serve as levers, through which muscular action may be 
utilized. 
In order to fulfil these functions, bones present many differ- 
ent points for study. They may be divided in a general way 
into: 
I. Long Bones, possessing a marrow cavity. 
II. Irregular Bones, those without a marrow cavity. 
In the study of a bone, notice: a. Its position and relation to 
other bones, b. The class to which it belongs, c. Give a descrip- 
tion of the appearances on the bone: whether there be surfaces, 
borders, extremities, shaft, depressions or elevations, and es- 
pecially note any. articular surface, that is, a surface produced 
by contact with another bone. An opening in a bone is called 
a foramen; a projection, a spine, tuberosity or tubercle; a de- 
pressed surface, a fossa, or depression; a smooth surface, a 
facet; a long elevation, a crest, ridge or border; either end, an 
extremity, the middle portion, the shaft or body. Other terms 
will be explained as they occur. 
In this connection it is proper to explain two technicalities of 
frequent use-Internal or mesial and External or lateral-these 
terms should be used with reference to the middle line or plane 
of the body, that is, one object is internal to another because it 
is nearer the middle line. They are often used incorrectly with 6 
DESCRIPTIVE ANATOMY. 
reference to a cavity; interior and exterior are the terms to be 
here employed. 
The bones are divided into those of the Vertebral Column; of 
the Thorax; of the Upper Extremity; of the Lower Extremity; 
of the Skull; the Hyoid; the Ossicula Auditus. 
The Vertebral Column. 
The vertebral column, or spine, consists of a series of sepa- 
rate bones, classed as irregular, called vertebrae, and extends 
from the base of the skull to the termination of the spinal column. 
It is flexuous in direction and of unequal size at different places; 
smallest in the neck, it gradually enlarges to below its middle 
and then suddenly tapers to a point. It transmits the weight of 
the head to the lower extremities, giving support on each side 
to the bones which enclose the thoracic cavity, and indirectly to 
those of the upper extremities. Towards its lower termination 
it has expanding from it on either side the bones which form 
the pelvis. It forms the receptacle for the spinal marrow and 
its envelopes. In the adult it consists of twenty-six pieces, called 
vertebrae, which are divided into four classes: 
In the neck-Cervical-seven in number. 
In the Thoracic region-Dorsal-twelve in number. 
In the Abdominal region-Lumbar-five in number. 
In the Pelvic region-Pelvic-two in number. 
The last are known as sacrum and coccyx, and before adult 
life are composed of nine pieces-the sacrum having five and 
the coccyx four. The vertebrae of the different regions have 
characteristics which distinguish them from those of other re- 
gions, and each vertebrae has certain less noticeable ones which 
designate its position in its own region. Each region, however, 
possesses one or more bones so widely different from the typical 
vertebrae of that region as to deserve the appellation of "Pecu- 
liar." 
Since there are appearances common to the vertebrae of all 
regions, these must be first noted. OSTEOLOGY. 
7 
A Typical Vertebra. 
Each vertebra consists of a central canal surrounded by the 
following parts: 1. body (corpus vertebrae) ; 2. foramen for the 
spinal cord, foramen vertebrale; 3. laminae (2) ; 4. pedicles (2), 
the laminae and pedicles form the arcus vertebrae; 5. spinous pro- 
cess (1); 6. transverse processes (2) ; 7. articular processes 
(4) ; 8. intervertebral notches (4). 
1. The body is the front, thick, massive portion of the bone, 
flattened above and below to articulate with adjoining bones, in- 
directly by the intervention of cartilage; it is more or less circu- 
lar in outline, but slightly flattened behind; the edges project 
somewhat in front and laterally, so as to produce a furrow on the 
front; its posterior aspect forms the anterior boundary of the 
spinal foramen. 
2. The spinal foramen (foramen vertebrale) lies between the 
body in front and the spinous process behind, and is bounded 
laterally by the pedicles and laminae. It is a large opening, 
varying in form and size in the different regions. 
3. The PEDICLE (radices arcus vertebrae) is the more or less 
rounded commencement of the lamina. 
4. Each lamina springs from the postero-lateral aspect of the 
body, through the medium of the pedicle, and arches backward 
to meet its fellow to form the spinous process, thus inclosing 
the spinal foramen. It is flattened from side to side, and pre- 
sents two borders, the upper, thin and sharp; the lower, thick 
and rounded. 
5. The spinous process juts backward from the union of the 
two laminae. 
6. The transverse process projects laterally from the verte- 
bral arch near the junction of the lamina and pedicle on either 
side. 
7. The articular processes are four, two superior and two in- 
ferior. They extend upward and downward from the laminae. 
8. The intervertebral notches are four, two superior and 
two inferior; they are furrows on the upper and lower aspects 
of the pedicles. 8 
DESCRIPTIVE ANATOMY. 
A Cervical Vertebra. 
The discrimination of a cervical vertebra involves the follow- 
ing points: it is the smallest; its body is smallest, having its 
transverse diameter greater than the antero-posterior; on its 
upper aspect the lateral edges are raised into ridges, while in 
front there is a depression above and a prolongation below of a 
lip of bone. The spinal foramen is the largest in the body and is 
triangular. The lamina is narrow and long, one surface facing 
upward, outward and backward, the other downward, forward 
and inward. The upper border is thin and overlapped by the 
thicker and longer lower border of the vertebra above. The 
spinous process is triangular and bifid at the extremity gen- 
erally, and is directed backward with a slight inclination down- 
ward. The transverse process is perforated at its base by an 
opening called the vertebral foramen (foramen transversarum), 
is grooved above and bifid at its extremity, forming two nodules 
which are called the anterior and posterior tubercles of the trans- 
verse processes. Its direction is outward and slightly down- 
ward. The articular processes are oblique, nearly circular, flat 
and articular; the superior face upward and backward, the in- 
ferior downward and forward. 
A Dorsal Vertebra. 
To discriminate a typical DORSAL VERTEBRA the following ap- 
pearances must be noted: 
The body is intermediate in size between that of a cervical 
and a lumbar vertebra; there is no great preponderance of the 
one diameter over the other, although in the upper part of the 
region the transverse is slightly greater, and in the middle por- 
tion the antero-posterior. There are no lateral lips, nor anterior 
depressions. The most characteristic feature is the appearance, 
on the postero-lateral aspect of the body, of articular half-facets, 
situated two on each side, at the upper and lower borders; these 
are for the reception of the heads of the ribs. The spinal fora- 
men is smaller than in the other regions, and is nearly round. 
The lamina is short, faces obliquely upward, backward and out- OSTEOLOGY. 
9 
ward, and is almost entirely covered by the origin of the pro- 
cesses which spring from it, and shows less tendency to imbri- 
cation than do the cervical laminae. The pedicle is deeply 
notched inferiorly, but shows only a slight groove above. The 
spinous process is triangular, and is distinguished from that of 
a cervical vertebra by not being bifid, it extends downward and 
slightly backward. The transverse process is peculiarly well 
marked, being large, long, not perforated at its base, and ex- 
tending outward, upward and backward, increasing in size as 
it removes from its origin so as to present an enlargement at 
its termination; that is, it is "clubbed." It bears on its anterior 
face, near its termination, an articular facet. The superior ar- 
ticular processes are vertical and look nearly backward and 
slightly outward; the inferior looking forward and inward. 
A Lumbar Vertebra. 
In the lumbar region the whole bone is more massive than in 
the cervical and dorsal regions. The body is large, its trans- 
verse diameter greater than the antero-posterior. Its anterior 
surface is concave from above downward, convex from side to 
side, slightly lipped above and below. The superior and in- 
ferior faces present a concave central portion with an elevated 
circumference. The posterior face, although nearly flat, pre- 
sents a slight concavity from above downward, and from side 
to side, with large openings for the veins. No lateral articular 
facets are seen on the body. The spinal foramen is obscurely 
triangular and is intermediate in size between the large cervical 
and small dorsal. The pedicles are short and thick, project 
nearly backward with but a slight inclination outward, and are 
marked below by deep and wide intervertebral notches. The 
superior notches are narrow and shallow. The laminse, short 
and massive, pass downward, backward and inward to join the 
spinous process, and are partly hidden by processes. The spi- 
nous process is nearly quadrilateral, strong and thick. It pro- 
jects straight backward and terminates in a blunt, rough, al- 
most clubbed, extremity. The transverse processes spring from 
the junction of the laminae and pedicles, and, like the cervical, 10 
DESCRIPTIVE ANATOMY. 
are situated in front of the articular processes. They project 
outward and backward, are not perforated at their bases, nor 
clubbed at their extremities; are long narrow, thin and curved, 
resembling a rib in shape. The superior articular processes are 
cut nearly vertically, as in the dorsal region, but, unlike the lat- 
ter, face toward each other so that their direction is backward 
and inward. They are concave from before backward to receive 
the inferior processes, and are situated at the junction of the 
pedicles and laminae. The inferior processes, situated entirely 
on the laminae, are vertical, convex from before backward and 
face outward and forward so as to be received between the in- 
verted superior processes. 
Peculiar Vertebrae. 
The foregoing description of a vertebra in each region is, as 
stated, of one typical of that region; and this typical vertebra 
is one from about the middle of the region. Toward the con- 
fines of each region the vertebrae partake more or less of the 
characters of those in the adjoining regions, and so far depart 
from the type as to deserve the appellation "Peculiar"-thus 
demanding a special description. The departure from the typi- 
cal vertebra is so great in some instances that the bones have 
received special names. 
In the cervical region there are three peculiar vertebrae-the 
first, second and seventh. 
The First Cervical Vertebra, or Atlas. 
This vertebra is known as the atlas, because it supports the 
weight of the head; it resembles only in a slight degree a typi- 
cal vertebra, having no body and being scarcely more than a 
ring of bone. It is described as consisting of four parts-two 
arches and two lateral masses, surrounding a spinal foramen of 
remarkable size, much larger than in any other vertebra. 
The lateral masses stand one on each side, being connected 
before and behind by the anterior and posterior arch. OSTEOLOGY. 
11 
The anterior arch (arcus anterior) is much shorter than the 
posterior, and forms one-fifth of the circumference of the bone; 
it presents on the middle of its front an elevation, called the an- 
terior tubercle of the Atlas, and opposite this, on the posterior 
face of the anterior arch, is a circular, concave articular facet 
for the odontoid process of the second vertebra. 
The posterior arch (arcus posterior) forms about two-fifths 
of the circumference of the bone. It is convex and rough behind, 
presenting in the mid-line a slight rough eminence called the 
posterior tubercle of the atlas-a rudimentary spinous process 
The upper border of the posterior arch presents, just behind the 
lateral mass, a deep groove or notch, the superior intervertebral 
notch, and below, behind the inferior articular process, a similar 
but slighter groove, the inferior intervertebral notch. It will 
be seen that the intervertebral notches are behind the articular 
processes in this vertebra instead of being in front as in a typi- 
cal vertebra. 
Each lateral mass (massa lateralis) forms about one-fifth of 
the bony circle, and sustains, above and below, the articular pro- 
cesses. The superior are oval, concave, oblique, articular pits, 
whose long diameter is directed from before backward and out- 
ward, approaching each other more nearly in front than behind, 
and looking, upward, inward, and forward. About their middle 
they are frequently slightly encroached upon by the nonarticular 
portion of the bone so as to give them something of a kidney 
shape. The inferior processes are smaller, circular, slightly con- 
cave or flat, and face downward, inward and slightly backward. 
The inner face of each lateral mass is marked, just below the 
superior articular process, by a slight tubercle intended for liga- 
mentous attachment. The transverse processes project outward 
and a little downward. They are large and prominent, per- 
forated at the base, but not marked by either groove or tubercle 
as in the typical vertebra. 
The Second Cervical Vertebra, or Axis (Epistropheus). 
The body of the atlas becomes ossified to the axis and appears 
on that bone as the edontoid process. This process occupies the 12 
DESCRIPTIVE ANATOMY. 
whole of the upper surface of the Axis, springing by a slightly 
constricted portion called the neck, ascending and enlarging for 
a short distance to again decrease and finally terminate in a 
blunt point. On either side, just below the termination, there 
is a rough depression for ligamentous attachment. Below this 
and on its anterior face, is a smooth circular, convex articular 
facet, to play on a similar surface on the back of the anterior 
arch of the atlas. Just opposite to this, on the posterior surface, 
is a second smooth surface for the play of the transverse liga- 
ment. 
The body is marked in front by a vertical ridge and on either 
side of this by a deep depression. 
The superior articular facets appear to be seated on the junc- 
tion of the pedicles and body. They are circular in form, nearly 
flat, and face upward and outward, possibly slightly forward. 
The transverse processes, less prominent than those of the 
Atlas, are not bifid, and pass downward and outward. They are 
pierced by the vertebral foramen, which runs from below up- 
ward toward the superior articular facet and then turns abruptly 
outward, forming nearly a right angle. 
The laminae are thick and strong. 
The spinous process, strong and thick, projects straight back- 
ward, is deeply grooved on its under surface and frequently bi- 
furcated at the extremity. There is barely a trace of a superior 
intervertebral notch, which lies behind the articular process. The 
lower portion of the bone presents the characteristics of a typi- 
cal cervical vertebra, but is more massive. If the vertebra be 
examined from above, it presents all the singularities of a pe- 
culiar vertebra. Viewed from below, the return to the type is 
seen in the articular processes looking forward and downward; 
the overhanging lip on the anterior part of the body, the groove 
on the spinous process; the foramen in the base of the trans- 
verse process; the thick lower border of the lamina, and the in- 
tervertebral notch in front of the articular process. It is the 
transitional vertebra. OSTEOLOGY. 
13 
Vertebra Prominens, or Seventh Cervical Vertebra. 
This vertebra derives its sobriquet of PROMINENS from its pos- 
session of a remarkably long, thick, non-bifid, spinous process, 
which distinguishes it from the other cervical vertebrae. It is 
also larger than the other vertebrae of this region, its spinal 
foramen is smaller and the lower surface of the body is more 
like that of a dorsal vertebra. 
Peculiar Dorsal Vertebrae. 
The peculia dorsal vertebra are the first, ninth, tenth, 
eleventh and twelfth. 
The first presents on each side of its body, above and postero- 
laterally, a whole facet for the head of a rib; below, in corre- 
sponding position, a half facet on each side. The ninth has but 
one demi-facet on each side, which is on the upper border. The 
tenth has one whole facet on each side above. The eleventh has 
one whole facet on each side, but its transverse process has no 
articular facet. The twelfth has one whole facet on each side; 
its transverse process has no articular facet and its inferior ar- 
ticular processes are everted. 
The Pelvic Vertebrae. 
The PELVIC vertebrae, specifically known as sacrum and coc- 
cyx, form the lower part of the vertebral column, and derive the 
appellation of pelvic from the fact that they form the posterior 
wall of the pelvis in the articulated skeleton. They are described 
separately. 
Sacrum (Os Sacrum). 
The sacrum (sacer-sacred), lies between the fifth lumbar ver- 
tebra above and the coccyx below, and between the two ossa in- 
nominata-one on either side. It is triangular in outline, its 
base being upward and its truncated apex below and backward 
and tipped by the coccyx. Its anterior face is concave, both from 14 
DESCRIPTIVE ANATOMY. 
above downward and from side to side, more so in men than in 
women, this being one means of distinguishing the sex to which 
the pelvis belonged. It is described as consisting of an anterior 
and posterior face, two lateral borders, a base, and an apex. 
The anterior face (facies pelvina) is concave and presents two 
vertical rows of foramina, of four each, one row on each side of 
the middle line, called the anterior sacral foramina; the upper 
two in each row are considerably larger than the lower two. 
Connecting each foramen with the corresponding one in the op- 
posite row is a ridge; these ridges marking the line of union of 
the five separate vertebrae of which the sacrum consisted in the 
young subject. Passing outward from each foramen is a groove 
for a sacral nerve. 
The posterior face (facies-dorsalis) of the sacrum is narrower 
than the anterior, is convex both from above downward and from 
side to side, and is rough. Above, in the mid-line, is seen the 
triangular opening of the spinal canal; below this is a row of 
rough projections, the rudimentary spinous processes. The 
upper two of these are usually distinct, while the two lower 
coalesce. The lowest spine is wanting and here the spinal canal 
is exposed. External to the sacral spines is seen a row of slight 
projections, the rudimentary articular processes, and between 
these and the spines is a rough vertical groove, the sacral, con- 
tinuous with the vertebral groove above. External to the ar- 
ticular tubercles is a row of foramina, the posterior sacral fora- 
mina, four in number, like those on the anterior face, but smaller 
in size and less regular in outline. External to these again, and 
nearly on the lateral border, is another row of rough tubercles, 
the rudimentary transverse processes. 
The lateral borders, broad and thick above; narrow, thin, and 
rough below, present supero-anteriorly a long, ear-shaped, rough, 
articular facet for the os innominatum, behind this a deep rough 
depression for ligamentous attachment. 
The base, or upper extremity, presents in the mid-line an oval 
articular surface, corresponding in shape and size to the lower 
surface of the last lumbar vertebra, with which it articulates. 
On either side of this is a broad, smooth expanded surface, called 
the wing of the sacrum. Behind the articular surface is seen OSTEOLOGY. 
15 
the triangular upper opening into the sacral canal, a continua- 
tion of the spinal canal. This canal passes through the sacrum, 
decreasing in size as it descends, and is open posteriorly below 
on account of the absence of the last spinous tubercle of the sa- 
crum. On either side of the opening is an articular process. 
These processes, like the superior articular processes of a lumbar 
vertebra, are concave from side to side and face toward each 
other. In front of the articular processes on either side is a 
groove corresponding to the intervertebral notch of other ver- 
tebrae. 
The ^pex, or lower extremity of the sacrum, presents an oval 
surface for articulation with the coccyx, and on either side of 
this an articular nodule, called the cornu. Behind the oval sur- 
face is the opening of the sacral canal which terminates the 
spinal canal. 
Coccyx (Os Coccygis). 
The coccyx forms the lower extremity of the vertebral col- 
umn ; it originally consists of four pieces, or vertebrae, united, in 
the adult, into one bone, which is sometimes ossified to the sa- 
crum. It is triangular in shape; its base is above, presenting an 
oval articular facet for the truncated apex of the sacrum and two 
cornua for the similar cornua of that bone; its apex is below and 
forward, the bone continuing the curve of the sacrum and fre- 
quently deviating to one side. 
The Vertebral Column as a Whole. 
Viewed as a whole, the vertebral column presents two pyra- 
mids with their bases opposed, the superior pyramid being com- 
posed of all the vertebrae from the second cervical to the last lum- 
bar, the inferior consisting of the nine pelvic vertebrae. On more 
careful examination it will be found that the superior pyramid 
may itself be divided into three, one extending from the second 
cervical to the first dorsal, base down, the second from the first 
to the fourth dorsal, base upward, and the last consisting of 
the remaining vertebrae with the base at the fifth lumbar. These 16 
DESCRIPTIVE ANATOMY. 
smaller pyramids are comparatively unimportant. Although the 
general direction of the vertebral column is vertical, it does not 
present a straight line. In the cervical region, and including the 
first and second dorsal vertebrae, it is convex forward, in the 
dorsal concave forward; in the lumbar, convex; and in the pel- 
vic again concave forward. Thus it will be seen to consist of 
alternate compensatory antero-posterior curves, an increase in 
the curvature of one region always causing a corresponding 
compensation in the region below. Viewed from the front we 
see the convex bodies of the vertebrae, marked by their trans- 
verse grooves and separated by the intervertebral disks, the 
whole presenting the curvatures above described. Posteriorly, 
in the mid-line, will be seen the spinous processes, rudimentary 
in the first cervical, prominent in the second, decreasing in size 
until the sixth is reached, well marked and prominent in the 
seventh, and even more prominent in the first dorsal. From this 
point the spines become longer in the dorsal region until the 
ninth is reached, but, owing to their downward inclination, less 
prominent. Again prominent and projecting backwards in the 
lumbar, they become indistinct in the upper sacral and disap- 
pear entirely in the lower sacral region. Sometimes there are 
normal deviations from the mid-line even in health, so that the 
spines do not form a straight line down the back. On either side 
of the spines is seen a groove which is broad and shallow in the 
cervical, deep in the dorsal and, becoming less marked in the 
lumbar, finally disappears in the lower pelvic region. The groove 
corresponds to the length of the laminae, extending from the 
origin of the spines to the base of the transverse processes. Lat- 
erally may be seen the sides of the bodies of the vertebrae, pre- 
senting in the cervical region the transverse processes, grooved 
by the intervertebral foramina; intervertebral foramina and 
transverse processes with articular facets for ribs, in the dorsal; 
and similar foramina and rib-like transverse processes in the 
lumbar region. The pelvic region shows the lateral border of 
the sacrum and coccyx. 
The length of the vertebral column varies at different periods 
of life and in different individuals. In the adult it is from 
twenty-four to twenty-eight inches long. OSTEOLOGY. 
17 
Sternum. 
The STERNUM, or breast-bone, forms 'the middle portion of the 
thoracic wall in front, the dorsal vertebrae occupying the mid- 
line behind; connecting these on each side are the ribs, which 
are prolonged by the costal cartilages. Extending outward from 
the upper end of the sternum on each side is the clavicle. The 
direction of the long axis of the sternum is downward and for- 
ward. Originally consisting of six parts, these in the adult be- 
come united into three-the upper, or manubrium, the middle, 
or gladiolus, and the lower, ensiform or xiphoid cartilage. These 
are united by cartilage, but later in life may become ossified 
together, the ensiform cartilage frequently becoming ossified and 
firmly united to the gladiolus. 
The manubrium, or first piece of the sternum, has an anterior 
and a posterior surface, upper and lower extremity and two 
lateral borders. The anterior surface is slightly convex from 
side to side, usually a little concave from above downward, and 
roughened for muscular attachment. The posterior is concave 
from above downward and from side to side, smooth, and marked 
by nutrient foramina. The upper extremity is marked in the 
mid-line by a notch known as the jugular (incisma jugularis). 
External to this and located at the junction of the upper extrem- 
ity and lateral border, is a smooth concavo-convex articular facet 
for the inner end of the clavicle (incisura clavicularis). This 
facet is concave from above downward and outward and convex 
from before backward. The inferior extremity is marked by an 
oval, oblong articular surface for the upper end of the gladiolus. 
The lateral borders present above a pit for the reception of the 
cartilage of the first rib; below a half pit for the second costal 
cartilage, converted into a whole pit by articulation with the 
gladiolus. Between these the border is rough, narrow, and non- 
articular. 
The gladiolus (corpus sterni), or second piece of the sternum, 
presents an anterior rough surface, slightly convex from above 
downward and marked by three transverse ridges which indi- 
cate the junction of the four bones of which it was originally 
composed. The posterior surface is concave and smooth. Both 
surfaces are marked by foramina for nutrient vessels. The 18 
DESCRIPTIVE ANATOMY. 
upper extremity shows an oval articular facet to correspond with 
the one on the lower extremity of the manubrium. The lower 
extremity shows a similar, but smaller, facet for the ensiform 
cartilage. The lateral borders are marked by a demi-facet at the 
upper and lower angles respectively and four whole pits between 
these two. The upper demi-facet is for the second costal carti- 
lage, the lower, for the seventh, and those between for the car- 
tilages of the intervening ribs. Between these pits are narrow, 
rough non-articular portions of bone. Occasionally the gladiolus 
is perforated near its lower end. 
The ensiform cartilage (processus xiphoideus) presents many 
varieties in shape and position. Above it has a small oval facet 
for the gladiolus, and on its lateral margin a half facet for the 
cartilage of the seventh rib. It is frequently deflected to one or 
the other side, and may be turned backward or forward. 
Viewed as a whole the sternum is convex and rough anteriorly, 
concave and smooth posteriorly, large and broad above, present- 
ing the articular facets for the clavicles and the jugular or in- 
terclavicular notch, narrow and pointed inferiorly. Laterally it 
is marked by pits for the reception of the cartilages of the seven 
true ribs. 
The Ribs (Costae). 
The ribs or costae are twelve pairs of long bones situated on 
the side and back and front of the chest and forming the greater 
part of the bony wall of the thorax. They are known by num- 
bers from above downward. In describing them a rib from the 
middle is taken and the characteristics common to all the ribs 
are described. This is called a typical rib. The peculiar ribs 
are then described. Of course all the ribs, from any given in- 
dividual, may be readily distinguished, but not those from dif- 
ferent persons. 
A Typical Rib 
A TYPICAL rib, being a long bone, has a shaft and two ex- 
tremities. OSTEOLOGY. 
19 
The posterior or vertebral extremity is sometimes improperly 
called the head. It consists of a head, neck and tubercle. The 
head presents two articular facets separated by an antero-pos- 
terior ridge. The facets look the one upward and inward, the 
other downward and inward, are oval in form and articular for 
the demi-facets found on the bodies of the dorsal vertebrae above 
and below. The ridge is received in the interval between the 
two vertebrae and is attached to the intervertebral disk. 
The neck (callum costae) extends outward and slightly back- 
ward from the head and terminates at the tubercle. It has an 
upper and a lower border, anterior and posterior surfaces. The 
posterior surface is irregular and rough for ligamentous at- 
tachment; the anterior, smooth, concave, slopes obliquely from 
above downward and enters into the formation of the posterior 
wall of the thorax. The tubercle (tuberculum costae) is found 
at the junction of the posterior surface of the neck with the 
shaft. It is a small, rough elevation surmounted by a round 
articular facet looking backward and inward, The lower border 
is twice as thick as the upper, is longer and roughened for the 
attachment of a ligament. The superior border is marked by 
a prominent crest which extends from the head to near the tu- 
bercle. In the lower ribs it rises from behind forward and ter- 
minates rather abruptly before reaching the tubercle; in the 
upper it is less prominent and might be described as a simple 
ridge marking the upper border. 
The anterior, or sternal, extremity, is flattened from before 
backwards, slightly larger than the shaft, and is surmounted 
by a pit for the reception of the corresponding costal cartilage. 
The shaft (corpus costae) slopes obliquely from above down- 
ward and forward, the degree of obliquity varying with the dif- 
ferent ribs. It presents two surfaces, internal and external, 
and two borders, inferior and superior. The posterior part of 
the shaft is nearly round and extends from the tubercle to the 
angle of the rib. Its surfaces look forward and backward. 
From the angle (angulus costae) the ribs slope and the surfaces 
become internal and external. The external surface is convex 
from before backward, flat or slightly convex from above down- 
ward, and is marked at the angle of the bone by an oblique 20 
DESCRIPTIVE ANATOMY. 
ridge. The internal surface is concave from before backward, 
convex from above downward and smooth. Near the lower 
border, which is thin and sharp, is seen a long groove (sulcus 
costae) which, starting near the tubercle, passes forward to the 
anterior third, where it gradually loses itself on the inferior 
border. The superior border is twice as thick as the inferior, 
and is slightly roughened for muscular attachment. The in- 
ferior border, thin and sharp, overhangs the groove on the 
inner surface and is itself marked by the same groove near its 
anterior extremity. 
Peculiar Ribs. 
The PECULIAR ribs are the first, second, tenth, eleventh, and 
twelfth. 
The first rib departs more widely from the typical rib than 
any other. Its surfaces look, one upward and forward, the other 
downward and backward; its borders look inward and outward. 
The superior surface, broad and flat, presents near the middle 
an oblique ridge which separates two grooves, the internal for 
the subclavian vein, the external for the subclavian artery. The 
inferior surface is smooth. The external border, convex and 
rough and thicker than the internal border, is not marked by 
either angle or ridge as is the case with a typical rib. The pos- 
terior extremity presents a head with only one articular facet, 
as this rib articulates with but one vertebra. The neck is flat- 
tened from above downward and has no crest. The anterior ex- 
tremity is thick and rough, being marked on its upper surface 
by a rough elevation for the attachment of a ligament. 
The second rib, longer than the first, approaches more nearly 
the typical rib. It is marked by a crest on its neck and an 
angle and ridge on the shaft, but both are less distinct than in 
the typical rib. 
The tenth, eleventh, and twelfth each has a whole facet, ar- 
ticulating with but a single vertebra. The tenth has a pit at 
its chondral extremity for the reception of a cartilage which 
binds it to the cartilage of the ninth and, through it, to the 
seventh. The eleventh and twelfth are merely tipped at their OSTEOLOGY. 
21 
extremity with cartilage and are called floating ribs, because 
they are not attached to any other rib. The eleventh and twelfth 
ribs have no articular facet on the tuberosity for the transverse 
process. 
The Costal Cartilages. 
The costal cartilages (cartilagia costalis) are flat pieces 
of hyaline cartilage attached by one extremity to the ribs and 
by the other to the pits on the lateral aspect of the sternum. 
Their surfaces are anterior and posterior and the borders su- 
perior and inferior. They increase in length from the first to 
the seventh and each has its separate pit on the sternum down 
to and including the seventh. From the eighth to the tenth the 
cartilages are attached to the cartilage of the seventh rib and 
through it to the sternum. The eleventh and twelfth are free. 
It is from this arrangement of the cartilages that the upper 
seven ribs are called vertebro-sternal, the next three, vertebro- 
chondral and the last two vertebral. The first three cartilages 
are horizontal, the next seven inclined obliquely upward, the 
obliquity increasing from the fourth to the tenth, while the last 
two are horizontal or inclined slightly downward. 
The Thorax. 
The THORAX is dome-shaped, apex above and base below. The 
superior opening (apertura thoracis superior) has an antero- 
posterior diameter of about two inches and a transverse of about 
four. The opening is kidney-shaped from the forward projec- 
tion of the first thoracic vertebra. The inferior opening (aper- 
tura inferior), much larger than the superior and broader 
transversely than from before backward, is higher in front than 
behind and slopes downward on either side so as to be much 
deeper laterally than in the mid-line. Posteriorly it presents a 
deep groove on either side of the vertebral column, the sulcus 
pulmonalis, which receives the thickest part of the lung. 22 
DESCRIPTIVE ANATOMY. 
The Clavicle (Clavicula.) 
The clavicle, or collar-bone, extends nearly horizontally out- 
ward, but is inclined slightly upward, from the upper end of the 
sternum on either side. It is a long bone, and like other long 
bones, is divided for study into a shaft and two extremities. 
The inner extremity (extremitas sternalis) is thick, the bone 
gradually diminishing in size as it passes from the inner to the 
outer end. The bone is round, or triangular, and bears on its 
inner extremity a concavo-convex articular surface, convex from 
above downward and outward, concave from before backward. 
This surface is intended for articulation with a similar saddle- 
shaped surface on the upper outer aspect of the first piece of the 
sternum. Generally, just below, and continuous with this, is 
found another articular facet to play upon the cartilage of the 
first rib. 
The outer extremity (extremitas acromialis) is flattened from 
above downward, rough and subcutaneous on its upper surface, 
slightly roughened on its lower surface, and presents at its 
tip a small articular facet, oval in outline, the long diameter 
directed from before backward, and looking downward and 
outward. This is for articulation with the acromion process 
of the scapula. 
The shaft of the bone presents two surfaces, superior and in- 
ferior; and two borders, anterior and posterior. The inferior 
surface presents a long shallow groove, the subclavian, termi- 
nated internally by the roughened surface which is sometimes 
a prominence and sometimes a depression, called the rhomboid 
impression. Following the groove outward, we reach, near the 
posterior border of the bone, a prominent tubercle, called the 
conoid; and extending outward and forward from this is a 
roughened ridge, called the trapezoid ridge. 
The superior surface is round and convex for its inner three- 
fourths, flattened for its outer one-fourth, roughened near the 
inner and outer extremities for muscular attachment, and is 
subcutaneous. 
The anterior border is convex for its inner two-thirds, thick 
and round; concave for its outer one-third, thin and sharp. OSTEOLOGY. 
23 
The posterior border is concave for its inner four-fifths, and 
is smooth; it is convex for its outer one-fifth, and is rough, 
thicker than the outer part of the anterior border, but not so 
thick as the inner extremity of the posterior border itself. The 
upper surface and anterior border are subcutaneous. 
The Scapula. 
The scapula, or shoulder blade, is a flat triangular bone, sit- 
uated on the upper postero-lateral aspect of the chest, extend- 
ing over the upper eight ribs with the exception of the first. It 
consists of a body having two surfaces and three borders, three 
angles, a spine, and two processes. 
The anterior face, (facies costalis) or venter, is concave, 
has ridges (linese musculares) running upward and outward, 
and presents a deep depression towards its upper outer part, 
which is called the subscapular angle. This face of the scapula 
is in the main occupied by the subscapular fossa; but it must 
be remembered that there are smooth surfaces at the superior 
and inferior angles of the bone, and along the posterior border, 
which, while belonging to the venter of the scapula, do not be- 
long to the subscapular fossa. 
The posterior face (facies dorsalis), or dorsum, is convex from 
above downward, presenting a prominent ridge, the spine, which 
commences at the posterior border and runs outward and up- 
ward towards the head, dividing the dorsum into two unequal 
parts; the smaller above, called the supraspinous fossa, and the 
three-fold larger below, called the infraspinous fossa. 
The supraspinous fossa is triangular in outline, the apex of 
the triangle being directed outward, is concave from above 
downward and from before backward, and smooth. 
The infraspinous fossa occupies nearly all of the remaining 
portion of the dorsum of the scapula; but there is a strip along 
the anterior, or axillary, border, and a triangular space at the 
inferior angle, which do not belong to the infraspinous fossa, 
though they belong to the dorsum of the scapula. The fossa, 
which is triangular in outline, the apex directed downward and 
the base upward, presents near its center a prominent bulge, 24 
DESCRIPTIVE ANATOMY. 
and external to this a broad vertical groove. External to this 
groove is a prominent ridge which separates this fossa from the 
strip along the axillary border of the scapula. It is useless to 
say that the spine furnishes a portion of both supra- and infra- 
spinous fossae. 
The spine, (spina scapulae) is triangular and presents three 
borders, two of which are free, one looking backward and the 
other outward and forward. The one which looks directly for- 
ward, the so-called "attached border," is simply the attachment 
of the spine to the remaining portion of the bone. The spine 
itself presents a superior surface which is concave, and enters 
into the formation of the supraspinous fossa, and an inferior 
surface which is slightly convex from without inward, slightly 
concave from above downward, smooth, and forms part of the 
infraspinous fossa. The posterior border of the spine is rough, 
commences as a smooth triangular surface near the vertebral 
border of the bone, rises as it passes forward, becomes thicker 
and rougher, and terminates near the upper outer angle by 
becoming a roughened projection of bone, known as the acro- 
mion process. The posterior border presents a superior lip, an 
inferior lip, and an intermediate space intended for muscular 
attachments. The superior lip becomes continuous with the 
internal border of the acromion process; the inferior, with the 
outer border, and the rough intervening space with the superior 
surface of that process. The external border of the spine is 
smooth, round, and concave, and is the inner limit of the groove 
which extends around it and forms the means of communica- 
tion between the supra- and infra-spinous fossae. 
The superior border (margo superior) of the scapula is thin, 
and is the shortest of the borders. Near its outer extremity it 
is deeply notched, the notch being known as the suprascapular 
notch. It terminates in the superior angle of the bone by join- 
ing with the posterior or vertebral border. 
The posterior or vertebral border, (margo vertebralis) com- 
mencing at the superior angle passes downward and inward to 
the point at which the spine springs from the posterior border. 
From this point downward it changes its direction, and is nearly 
vertical, with a slight inclination outward. This border of the OSTEOLOGY. 
25 
scapula, like the posterior border of the spine, is composed of 
two lips and a rough intervening space. It is intermediate in 
thickness between the superior and the axillary borders. 
The anterior, or axillary, or oziter border (margo axillaris) is 
thick. Just below the external angle of the bone it presents a 
rough impression (tuberositas infraglenoidalis) from one-half to 
three-quarters of an inch in length, which is intended for mus- 
cular attachment. Below this point is seen a vertical groove, 
which passing downward upon the axillary border winds grad- 
ually to the posterior surface of the bone, which it reaches at 
the junction of the lower third with the upper two-thirds of 
the axillary border. Starting from the rough impression is a 
vertical ridge, which is the posterior boundary of the above- 
mentioned groove. Crossing this ridge at the middle of the 
axillary border of the scapula is a transverse groove which 
transmits an artery from the anterior to the posterior surface 
of the scapula. Below the termination of the vertical groove 
the axillary border of the scapula becomes thinner, and is 
roughened for muscular attachment. 
Of the angles of the bone the superior (angulus medialis) is 
situated at the junction of the superior and posterior borders, 
and is about a right angle. It is usually deflected slightly back- 
ward; and presents anteriorly a smooth surface, belonging to 
the venter of the scapula, but not entering into the subscapular 
fossa. 
The inferior angle, (angulus inferior) at the junction of the 
posterior and axillary borders, is acute, having a roughened 
surface anteriorly and posteriorly, giving attachment to power- 
ful muscular fibres. 
The anterior angle, (angulus lateralis) is expanded, and is 
the thickest portion of the bone. It is frequently called the 
"head" of the bone; and bears upon its extremity a shallow, 
oblong, vertical concavity, known as the glenoid cavity. This 
cavity has its long diameter directed from above downward. 
It is pyriform in outline, with the large end below and the small 
end above. It is supported upon the bone by a narrow con- 
stricted portion, which is called the "neck" of the scapula. 26 
DESCRIPTIVE ANATOMY. 
This neck is distinct anteriorly and posteriorly; but above is 
obscured by the origin of the coracoid process of the bone, and 
below by the impression for the attachment of the triceps muscle. 
The processes are two: the coracoid process and acromion. 
The coracoid process (processus coracoideus) springs from 
the bone just above the glenoid cavity. Its direction is at first 
upward and slightly forward, but after passing a short distance, 
about half-an-inch, it abruptly changes its course, and runs 
nearly outward, with a slight inclination forward. At its origin 
one surface looks upward and backward and the other down- 
ward and forward; but after the change in its direction the first 
surface looks upward and forward and the other one downward 
and backward. The upper surface is roughened for muscular 
attachment, while the lower is smooth and concave. The tip is 
marked by a smooth impression for muscular attachment. 
The acromion process is the termination of the spine. It 
presents one surface which looks upward and backward, one 
which looks downward and forward, an external border, an 
internal border, and an apex. 
The superior surface is rough, irregular and subcutaneous; 
the inferior surface is rather smooth, is concave, and is pierced 
by numerous nutrient foramina. The external border is convex 
and rough for muscular attachment. The internal border is 
concave and is marked near its outer extremity by a smooth, 
oblong articular facet, the long diameter of which extends from 
before backward. The surface itself is oblique, looking inward 
and slightly upward. The apex is roughened for muscular at- 
tachment. The upper surface of this process is a continuation 
of the posterior border of the spine, whose superior lip corre- 
sponds to the inner border of the process, the lower lip to the 
outer border, while the rough intermediate lip expands into the 
upper surface. 
The Humerus. 
The humerus (L. humerus), or skeleton of the arm, is a long 
bone having a shaft and two extremities. OSTEOLOGY. 
27 
The upper extremity presents for examination a smooth, 
rounded portion, the head proper, (caput humeri), forming 
something less than half a sphere, which looks upward, inward 
and backward, and is articular for the glenoid cavity of the 
scapula. External to this is a constricted part of the bone, 
called the anatomical neck, which is narrow and well marked 
above, but becomes indistinct below and behind. External to 
the anatomical neck there is a large projection called the greater 
tuberosity (tuberculum majus). It is prominent and bulging, 
looks upward, outward and forward, and is marked by three 
impressions for the attachment of three of the muscles of the 
scapular group. Externally it is rough and prominent, but 
gradually slopes to blend with the shaft. Internal and anterior 
to the greater is a smaller projection called the lesser tuberosity 
(tuberculum minus). It is sharper and more prominent than 
the greater tuberosity, and has on its summit but one muscular 
impression. Descending from the inner border of the greater, 
and the outer border of the lesser, tuberosity are prominent 
rough ridges, bounding a deep vertical groove (sulcus inter- 
tubercularis) which separates the tuberosities. The groove is 
the bicipital and the ridges are known as inner and outer bi- 
cipital ridges. Below the tuberosities the bone is constricted 
and round, forming the surgical neck. 
The lower extremity is flattened from before backward, is 
bent forward, and presents a slight curve of torsion from with- 
out inward. On either side is a rough prominence called, im- 
properly, the condyle, internal and external, the internal being 
the larger of the two. From either condyle there passes up to 
the shaft of the bone a large ridge of which the external is much 
more prominent and curved than the internal. Proceeding now 
from the external condyle (epicondylus lateralis) inward, we 
next see a rounded articular surface, the eminentia capitata, 
(capitulum humeri) whose articular surface extends higher up 
anteriorly than posteriorly. It is for articulation with the cup- 
like cavity on the upper extremity of the radius. Internal to 
this is a shallow articular groove for the play of the rim around 
the head of the radius. Internal to this we encounter two an- 
tero-posterior articular ridges, separated by an antero-posterior DESCRIPTIVE ANATOMY. 
28 
articular groove, the three forming a trochlear surface (troch- 
lea humeri) for the reception of the greater sigmoid cavity of the 
ulna. The internal ridge is larger and its articular surface 
extends higher up in front than the external. Above the troch- 
lea, both before and behind, is a deep pit-like depression. The 
one in front is for the reception of the coronoid process of the 
ulna, the one behind for the olecranon. The olecranon fossa is 
deeper and larger than the coronoid. In some bones, the thin 
septum separating the two cavities is absent and then there is 
a foramen between the two fossae. Between the inner condyle 
(epicondylus medialis) and the internal surface of the trochlea, 
is a deep depression for the passage of an important nerve. 
The shaft of the bone, cylindrical above, prismoid in the mid- 
dle and below, presents three surfaces and three borders. The 
borders are anterior and two lateral; the surfaces, posterior and 
two lateral. 
The anterior border begins at the greater tuberosity as the 
external, or anterior bicipital ridge. Prominent and well 
marked above, it passes down the mid-line of the bone to ter- 
minate at the coronoid fossa, separating the internal from the 
external surface. The internal border begins above as the inner 
bicipital ridge. It passes at first downward and backward, then 
vertically downward to terminate as the internal condyloid ridge 
(margo medialis). It is prominent above and below, less dis- 
tinct in the middle of its course. 
The external border commences at the back of the greater 
tuberosity and passes straight down to the outer condyle where 
it becomes the external condyloid ridge (margo lateralis). Very 
sharp and prominent below, rough and well marked above, it 
is obliterated in the middle by the passage of the musculo- 
spinal groove. 
The internal surface begins as the bottom of the bicipital 
groove. It passes downward and backward at first and then 
vertically downward. It is narrow above, wider in the middle 
and smooth and looking forward and inward below. This sur- 
face is usually marked about its middle by the nutrient foramen, 
though this appearance is often found on the inner border. OSTEOLOGY. 
29 
The external surface begins at the base of the greater tuber- 
osity, passes straight downward to the middle of the bone, and 
then curves forward until it is almost anterior. About the 
middle of this surface there is a large rough surface, with the 
apex downward, called the deltoid impression from its supposed 
resemblance to the Greek "Delta" inverted. Below the apex 
of the impression the musculo-spiral groove crosses to the front, 
smoothing the outer face, which remains smooth and without 
appearances throughout. 
The posterior face is round and smooth above, but becomes 
broad and flat below. Commencing on the posterior surface 
and winding downward and outward, is a broad shallow groove, 
the musculo-spiral. This groove is indistinct on the posterior 
face, obliterates about two inches of the outer border, and is 
finally lost on the external face. 
The Ulna. 
The ULNA is a long bone, consisting of a shaft and two ex- 
tremities, distinguished as upper and lower. It is the inner 
and more massive of the bones of the forearm. 
The upper extremity is composed of two processes called ole- 
cranon and coronoid. 
The olecranon process is found occupying the summit of the 
bone, and may itself be divided for study into a superior, pos- 
terior and anterior surface and two lateral borders. The upper 
surface, indistinctly quadrilateral in outline, terminates an- 
teriorly in a bluntly pointed projection called the beak, and is 
marked by a rough surface posteriorly for the attachment of 
a muscle, while in front is found a transverse groove extending 
backward to become continuous with grooves which mark the 
lateral borders. The posterior surface is triangular in form, 
the large end of the triangle-directed upward, rough and sub- 
cutaneous. The anterior surface is concave from above down- 
ward, convex from side to side, articular, and enters into the 
formation of the greater sigmoid cavity (incisura semilunaris). 
The coronoid process juts forward from the front of the bone. 
It is triangular in form, the base of the triangle being attached 30 
DESCRIPTIVE ANATOMY. 
to the bone, while the apex points forward. It presents a su- 
perior and an inferior surface and two lateral margins. The 
superior surface is smooth and articular, convex from side to 
side, concave from before backward, and is continuous with the 
similar surface on the olecranon process. The inferior surface 
is very irregular. It is marked near its middle by a rough im- 
pression for the attachment of a muscle, the brachialis anticus; 
at its junction with the shaft, usually, by a slight projection, 
the tubercle of the ulna, and at its junction with the internal 
margin by a roughened elevation also for muscular attachment. 
The inner margin is roughened for muscular attachment; 
the external presents a concave, oval, articular facet, the long 
diameter from before backward, which receives the rim around 
the head of the radius. It is called the lesser sigmoid cavity of 
the ulna (incisura radialis). The greater sigmoid cavity is 
formed by the two processes, is concave from above downward, 
convex from side to side, and might be described as consisting 
of four depressions, two on either process, to receive the articu- 
lar ridges on the humerus, separated by a vertical ridge and a 
transverse groove. The outer side of this cavity is continuous 
with the lesser sigmoid cavity. 
The lower extremity of the ulna is much smaller than the 
upper, and consists of two projections separated by a rough 
notch, the inner on the postero-internal aspect of the bone is 
the smaller and longer, and terminates in a blunt point. It is 
called the styloid process of the ulna. The outer process is 
called the capitulum ulnae (dim. of Latin caput, head) and is 
articular upon its summit and around the greater portion of 
its circumference. The notch which separates the two processes 
is narrow, and is intended for the attachment of the fibro-car- 
tilage which enters into the formation of the wrist joint. The 
articular surface upon the summit is smooth, slightly concave, 
and does not directly articulate with the carpus but only through 
the interposition of the fibro-cartilage. The articular rim which 
surrounds three-fourths of its circumference is smooth and con- 
vex, and intended to play in the cavity which is found upon the 
lower extremity of the radius. OSTEOLOGY. 
31 
The shaft of the ulna is distinctly three-sided; and hence 
presents three borders and three surfaces. The surfaces are 
anterior, internal and posterior; the borders are anterior, pos- 
terior and external, or interosseous. 
The anterior surface (facies volaris) begins at the base of the 
coronoid process and terminates below at the capitulum ulnae. 
It is broad above, narrow and round below. For the upper 
three-fourths of its course it is usually concave from side to 
side, presenting a shallow groove. 
The subcutaneous internal surface (facies medialis) is broad, 
and flattened above, convex and slightly narrower in the middle, 
round and narrow below. 
The posterior surface (facies dorsalis), which faces outward 
and backward, is widest about its middle and presents usually 
a vertical ridge, which divides it into two unequal portions, of 
which the inner part is usually the broader. The upper portion 
of this surface presents a small triangular space; below it is 
rounded like the remaining surfaces. 
The anterior border (margo volaris) begins above at the inner 
side of the base of the coronoid process. Prominent and well- 
marked above, it passes downward to the front of the styloid 
process, becoming rounder and more indistinct in the lower one- 
third of its course. 
The posterior border (margo dorsalis) commences above at 
the apex of the triangle of the posterior surface of the olecranon 
process. Prominent and well-marked above, subcutaneous 
throughout, it becomes round and smooth below, and terminates 
at the back of the styloid process. 
The external or interosseous border (crista interossea) com- 
mences by the convergence of two lines, one from either side 
of the lesser sigmoid cavity. It is sharp, thin, and well-marked 
for the middle two-fourths of its course. Below it becomes in- 
distinct or imperceptible, and terminates at the front of the 
capitulum ulnae. 32 
DESCRIPTIVE ANATOMY. 
The Radius. 
The RADIUS (L. radius, a ray, or spoke of a wheel) is the outer 
of the two bones of the forearm; and like other long bones it is 
divided into a shaft and two extremities. 
Its upper extremity, unlike the ulna, is much smaller than its 
lower; and presents for examination a head upon whose summit 
is an articular, cup-shaped depression (fovea capituli radii) for 
articulation with the eminentia capitata of the humerus. This 
depression is surrounded by an articular rim; and is supported 
upon a constricted portion called the "neck," which terminates 
below on its inner aspect in a prominent projection, called the 
tubercle or bicipital tuberosity of the radius. This tuberosity 
presents posteriorly a prominent rough elevation, for muscular 
attachment, while anteriorly it has a smooth surface for the play 
of a bursa. 
On the large lower extremity we find the summit presenting 
a triangular articular cavity, the carpal, with its apex directed 
outward, and terminating in a point or projection, called the 
styloid process. The base is directed inward, and is continuous 
with the articular facet found on the inner aspect of the lower 
extremity. 
The carpal cavity (facies articularis carpea) is divided into 
two portions by a slight antero-posterior ridge. The external 
portion is continued from the summit of the bone on to the inner 
face of the styloid process, and is triangular in form. The in- 
ternal portion, quadrilateral in form, is separated by a slight, 
non-articular ridge from the smooth oval, oblong articular facet, 
whose long diameter is directed from before backward, found 
on the inner face of the lower extremity, and called the sigmoid 
cavity (incisura ulnaris) of the radius. 
The anterior face of the lower extremity is rough, and projects 
forward. 
The posterior face is rough and irregular. It is marked by 
five vertical grooves with intervening ridges. Two of these 
grooves are found upon the styloid process. Next to the styloid 
process is a broad, shallow groove for the transmission of two 
tendons; then a prominent, subcutaneous ridge, overhanging a OSTEOLOGY. 
33 
very narrow, deep groove; and, lastly, a shallow groove near 
the inner end of the posterior face. 
The styloid process itself presents an internal and an external 
face; the internal being articular, and continuous with the ar- 
ticular surface of the carpal cavity; the external rough for liga- 
mentous attachment, and marked by the two grooves above 
mentioned. Its anterior and. posterior borders are roughened, 
while its tip has a blunt point. 
The shaft of the radius is bowed, so as to be convex outward 
and backward, and has three surfaces and three borders. The 
surfaces are anterior, posterior, and external; the borders an- 
terior, posterior, and internal or interosseous. 
The anterior face (facies volaris) is narrow above and slightly 
convex, becomes broader as it approaches the lower extremity 
of the bone, is slightly concave both from side to side and above 
downward in the middle and is flat at the lower end. It is 
marked by an oblique line, which will be mentioned later. 
The posterior face (facies dorsalis) is convex in the upper 
and lower portions of its course, slightly concave or grooved in 
the middle. 
The external face (facies lateralis) is convex and rough 
throughout its extent. 
The anterior border begins at the front of the bicipital tuber- 
osity ; it passes downward and outward, crossing the upper one- 
third of the bone until it reaches its middle third, in which situa- 
tion it is known as the oblique line of the radius mentioned 
above. From this point it continues vertically downward to the 
front of the styloid process of the radius, where it terminates. 
The posterior border (margo dorsalis) begins at the back of 
the neck of the radius, and running vertically downward, more 
prominent in the middle than elsewhere, terminates at the back 
of the styloid process. 
The internal border, or interosseous ridge (crista interossea) 
begins also at the tuberosity near its posterior portion, passes 
downward, sharp and prominent about its middle, more in- 
distinct below, and terminates at the lower extremity of the 
bone, by dividing into two lines which enclose the sigmoid cavity 
of the radius. DESCRIPTIVE ANATOMY. 
34 
The Hand. 
The skeleton of the hand consists of the skeleton of the Car- 
pus, the Metacarpus, and Phalanges. 
The Carpus. 
The skeleton of the carpus or wrist, consists of seven small, 
irregular bones, arranged in two rows one above the other; in 
the upper row are three bones, arranged in the following order 
from without inward: 1. the scaphoid; 2. the semilunar; 3. the 
cuneiform, on the front of which plays a sesamoid bone, called 
the pisiform. In the lower row in the same order are: 1. the 
trapezium; 2. the trapezoid; 3. the os magnum; 4. the unciform. 
The Bones of the Upper Row. 
The bones of the upper row articulate laterally with one 
another; the bones on the inner and outer side respectively have 
no bones on the inner side of the one and the outer side of the 
other, and hence there is no articular surface on that aspect of 
the bones. It must be further noted that viewed from the 
back there appear to be but three bones in the upper row, placed 
laterally, the scaphoid, semilunar and cuneiform; but viewed 
from the front the pisiform is seen perched upon the cuneiform, 
so that the latter bone has no articular facet on its inner side. 
The Scaphoid (Os Naviculare). 
The first bone of the first row has a superior surface, which 
is rounded, convex, and articular for the lower end of radius; 
an inferior surface, which is concave and articular for the upper 
extremity of the os magnum; an older extremity, which looks 
downward and outward, and is articular for the trapezium and 
trapezoid; an inner extremity with an oval articular facet, 
whose long diameter is directed from before backward, for ar- 
ticulation with a similar facet upon the semilunar. Like all the 
bones of the carpus, the anterior and posterior surfaces are OSTEOLOGY. 
35 
non-articular; but unlike most carpal bones, the anterior sur- 
face is broader than the posterior. 
Hold the convex radial surface upward, the narrow grooved 
face backwards; the tuberosity will then point to the side to 
which it belongs. 
The Semilunar (Os Lunatum). 
The second bone in the first row has a superior surface, con- 
vex, smooth, and articular for lower end of radius; an inferior 
surface having two articular facets, one concave, oval, with its 
long diameter antero-posterior, articular for the head of the os 
magnum, the other long and narrow for the unciform; an 
outer edge, articular for the scaphoid; and an inner, triangular 
in shape, larger in size than the outer one, and articular for 
the cuneiform. The anterior and posterior surfaces are rough- 
ened and non-articular. The anterior surface is broader than 
the posterior, as is the case with the scaphoid. 
When the convex face is held upward, the narrow rough face 
backward, the small outer articular facet will point to the side 
to which it belongs. 
The Cuneiform (Os Triquetum). 
The third bone of the first row presents an inferior surface, 
concavo-convex for articulation with the unciform; an external 
surface, flat, slightly triangular, articular for the semilunar; 
an antero-internal surface, which is articular for the pisiform, 
while internally it terminates in a blunt projection which is not 
articular. The posterior surface is broad and rough, the an- 
terior surface is rough and narrow. It is usually said that this 
bone is articular upon its anterior face; but the surface which 
receives the pisiform bone looks upward more than forward, 
and is also directed slightly inward. 
When the circular facet is turned forward and the base 
upward, the concavo-convex face for the unciform points to the 
side to which it belongs. 36 
DESCRIPTIVE ANATOMY. 
The Pisiform (Os Pisiforme). 
The fourth bone of the first row is a rounded bone; and is in 
reality only a sesamoid bone, embraced by the tendon of the 
flexor carpi ulnaris. It is articular upon only one surface, the 
surface which looks downward and backward. It is generally 
described as being the only bone of the carpus which is articu- 
lar upon its posterior surface. 
Hold the bone with the articular surface downward, the non- 
articular part of the same surface backward; the inner concave 
surface will point to the side to which it belongs. (Gray.) 
The Bones of the Lower Row. 
The Trapezium (Os Multangulum Majus). 
The first bone of the second row is easily distinguished by the 
possession of a concavo-convex, or saddle-shaped articular sur- 
face, which is directed downward and outward. This is its in- 
ferior surface. Its superior surface is marked by a smooth, 
concave articular surface for the reception of the outer end of 
the scaphoid. The outer surface is rough, prominent and non- 
articular. The inner face is marked above by a smooth concave 
articular surface for the outer face of the trapezoid, while be- 
low this, separated from it by a rough groove, is a flat sur- 
face, looking downward and inward for the second metacarpal. 
Its posterior surface, broader than its anterior, is rough and 
prominent, while the anterior surface is easily distinguished by 
an oblique groove, which runs from above downward and in- 
ward. 
When the grooved face looks forward and the broad non-ar- 
ticular face backward, the concavo-convex facet looking down- 
ward and outward, points to the side to which the bone be- 
longs. OSTEOLOGY. 
37 
The Trapezoid (Os Multangulum Minus). 
The second bone of the second row can be most easily dis- 
tinguished by exclusion, having none of the characteristics of 
the other bones. It has a broad, somewhat quadrilateral pos- 
terior surface; a narrow and roughened anterior surface. Its 
superior surface is concave, and articular for the head of the 
scaphoid. Its external surface is slightly convex above for ar- 
ticulation with the trapezium. The inferior surface is con- 
cave from before backward, and articular for the head of the 
second metacarpal bone; while the internal surface is also con- 
cave from before backward, and articular for the lateral aspect 
of the os magnum. 
Hold the broad non-articular face backward with its apex 
pointing downward and inward, the concave face for the mag- 
num will point inward and the convex facet for the trapezium 
outward to the side to which it belongs. 
The Os Magnum (Os Capitatum). 
The third bone of the second row presents superiorly a 
rounded articular head to be received in the cavity which is 
furnished by the scaphoid and semilunar bones, the articular 
surface extending further on its posterior than on its anterior 
aspect. Inferiorly it presents a quadrilateral, oblique articular 
facet, which articulates with the upper extremity of the third 
metacarpal bone, and which is continuous with the articular 
facet found upon its inferior and external lateral aspect for the 
inner edge of the upper extremity of the second metacarpal 
bone. The outer surface presents an articular facet, at the an- 
terior inferior angle, convex from before backward, for articu- 
lation with the inner face of the trapezoid. The internal surface 
presents near its posterior margin an articular facet, broader 
above than below and somewhat L-shaped, the large end of 
the L directed upward. This is for articulation with the outer 
face of the unciform. The posterior surface is broad, rough, 
and marked by a depression just below the articular head; the DESCRIPTIVE ANATOMY. 
38 
anterior face, narrower, than the posterior, is bulging and 
prominent, and roughened for ligamentous attachment. 
When the round head looks upward and the broad non-ar- 
ticular face backward, the convex facets for the scaphoid and 
trapezoid will point to the side to which it belongs. 
The Unciform (Os Hamatum). 
The fourth bone of the second row is more easily distin- 
guished than any bone of the hand. Its upper face looks upward 
and inward; and is frequently described as its internal face. 
This face is intended for articulation with the cuneiform; and 
presents like that bone a concavo-convex articular surface, which 
is continuous with the upper extremity of the bone, also convex, 
for articulation with the semilunar. Its outer face looks out- 
ward and slightly downward; and is marked near the posterior 
surface by an L-shaped facet, similar to the one found on the 
inner surface of the os magnum, and intended for articulation 
with that bone. Its inferior surface is marked by two articular 
facets, separated by a slight ridge, these facets articulating with 
the fourth and fifth metacarpal bones. Its posterior face, much 
broaded than the anterior, is roughened for ligamentous at- 
tachment. The anterior face will be at once distinguished by 
a very prominent projection found on the lower inner face of 
the bone. This projection, named the unciform process, looks 
forward and slightly outward, being a little curved in its course. 
It is one of the prominent land-marks of the hand. The re- 
mainder of the anterior face is roughened for ligamentous at- 
tachment. 
Hold the apex upward and the process forward. The con- 
cavity of the latter points to the side to which it belongs. 
The carpus as a whole presents us with four separate sets of 
articulations, viz.: 1. The articulation between the upper row 
of the carpus and the wrist. When examined in the articulated 
skeleton, it is seen that the superior row presents a condyle, 
oblong, oval and articular. The long diameter of this condyle 
is transverse; the bones which form it are from without in- 
ward: the scaphoid, semilunar and cuneiform; the pisiform not OSTEOLOGY. 
39 
entering into its formation. 2. The articulation between the 
two rows of carpal bones is sinuous in outline, or concavo-con- 
vex, the trapezium and trapezoid together forming a cavity for 
the reception of the head of the scaphoid, while the head of the 
os magnum and the upper end of the unciform form together 
a convex articular surface received into a concavity which is 
contributed to by the scaphoid, the semilunar, and the cunei- 
form. 3. The articulation between the bones of the second row 
and the metacarpal bones consists first of a saddle-shaped ar- 
ticulation, the trapezo-metacarpal; while the remaining articu- 
lations vary in form with the varying surfaces found upon the 
extremities of the metacarpal bones and the corresponding sur- 
faces on the carpal. 4. The articulations between the carpal 
bones themselves have been mentioned in the description of those 
bones. It will be noticed that none of these bones are articular 
on their posterior and anterior aspects, though it is said that 
the cuneiform is articular anteriorly and the pisiform pos- 
teriorly, but these surfaces do not look directly forward and 
backward. When viewed from its posterior aspect, the first 
row presents a set of but three bones, the pisiform not being 
seen from the posterior face. It will be noticed that the carpal 
bones taken as a whole form an arch whose concavity is di- 
rectly to the front, and whose convexity is directed backward. 
Hence it can be readily seen that all of the bones of the carpus, 
with the two exceptions mentioned, are broader upon their pos- 
terior than upon their anterior aspect. This arch gives strength 
to the hand, while at the same time permitting the necessary 
flexibility. 
Metacarpus. 
The metacarpus is formed by five bones classed as long bones; 
four of these, for the four fingers, being nearly parallel, while 
the fifth-for the thumb-recedes from the others as it descends. 
The metacarpal bones articulate above with the lower row of the 
carpus; below with the upper extremity of the first phalanges. 
At their upper ends they articulate laterally with one another, 
except the metacarpal bone of the thumb; but at the lower end 40 
DESCRIPTIVE ANATOMY. 
they do not articulate with one another. The metacarpus, like 
the carpus, is arched transversely, the convexity being pos- 
terior. One of its constituents may be thus described: 
A Typical Metacarpal Bone. 
The metacarpal BONES are long bones, presenting a shaft 
and two extremities, the upper extremity, called the base, and 
the lower, called the head. 
The upper extremity (basis), is quadrilateral, and presents an- 
terior and posterior surfaces, of which the posterior surface 
is the broader, these two surfaces being roughened for ligamen- 
tous attachment; two lateral surfaces, which are marked by ar- 
ticular facets, intended for articulation with the adjoining me- 
tacarpal bones. The summit of the bone is marked by a quad- 
rilateral articular facet, for articulation, with one of the car- 
pal bones of the second row. 
The lower extremity (capitrdum), or head, terminates in an 
articular surface, oblong antero-posteriorly, and articular higher 
up in front than behind. On either side of this surface is a de- 
pression, and behind this depression is a well-marked tubercle. 
Posteriorly the lower extremity is flattened and rough, while 
anteriorly it presents a slight groove, caused by the passage 
of the tendons of the flexor muscles. 
The shaft is triangular and arched, with the convexity of the 
arch directed backward. It presents a posterior and two lateral 
faces, an anterior and two lateral borders. 
The posterior face at its upper end presents a median longi- 
tudinal ridge, with a slight depression upon either side of it. 
This ridge, as it passes downward, divides about the middle 
of the bone into two; each, gradually separating, descends to 
reach the tubercle above the lateral depression on the lower 
extremity and forming the two lateral borders of the shaft. 
The triangular space between these diverging ridges is flattened. 
The lateral faces are concave and smooth from above down- 
ward, so that each pair of bones would leave between them a 
space for the attachment of muscles. These are known as the 
interosseous spaces. OSTEOLOGY. 
41 
The bone is concave towards its anterior aspect, and marked 
by the anterior border, which is a rather indistinct vertical 
ridge separating the lateral faces from one another. 
This description applies more or less closely to all the meta- 
carpal bones; but each possesses appearances characteristic of 
itself, by which it may be discriminated. Each bone is known 
by the name of the finger which it supports; but the metacarpal 
bones are also known by numbers from without inward. 
The metacarpal bone of the thumb, or first metacarpal, is 
the shortest and largest. Its posterior surface is broader and 
flatter than the remaining bones, and its lateral borders are 
more distinctly marked while upon its base it bears a saddle- 
shaped or concavo-convex articular surface, concave from be- 
fore backward, and convex from side to side. This with the 
absence of any lateral articular facet will distinguish it from 
the other bones of the metacarpus. 
The metacarpal bone of the index finger, or second metacarpal, 
is the longest, is next in size to that of the thumb, while its base 
presents four articular facets, three of which are upon the sum- 
mit; one, on the outer edge, flattened for articulation with the 
trapezium; one, in the middle, concave for articulation with the 
trapezoid, and one, on the inner edge, for articulation with the 
os magnum, and one upon the internal aspect for articulation 
with the metacarpal bone of the second finger. 
The metacarpal bone of the second finger, or third metacar- 
pal, is next in size and in length. On its base it presents an 
articular facet for the os magnum; on its outer lateral aspect 
an articular facet for the metacarpal bone of the index finger; 
on its inner lateral aspect an articular facet for the metacarpal 
bone of the ring finger, while its upper outer posterior aspect 
is prolonged into a styloid process, projecting upward between 
the trapezoid and the os magnum. On its inner lateral aspect 
the articular facet is divided into two by a groove. 
The metacarpal bone of the ring finger, or fourth metacarpal, 
next in size and length, is the typical metacarpal bone. The 
summit of its base articulates with the os magnum and the un- 
ciform. On its external lateral aspect a groove divides the ar- 
ticular facet into two for the two corresponding facets on the 42 
DESCRIPTIVE ANATOMY. 
inner lateral aspect of the metacarpal bone of the middle finger. 
On its internal lateral aspect is a facet for the fifth metacarpal. 
The metacarpal bone of the little finger, or fifth metacarpal, 
is the smallest. Its base presents a superior articular facet for 
the unciform, and a lateral facet on its outer aspect for the cor- 
responding facet on the metacarpal bone of the ring finger. 
On the inside of the base is a rough and prominent tuberosity 
with no lateral articular facet, which in itself distinguishes 
it from the other metacarpal bones. 
The Phalanges. 
The phalanges consist of three rows of long bones, extend- 
ing from the heads of the metacarpal bones to the tips of the 
fingers. The rows are numbered from the metacarpal bones, 
first, second, and third, the third row being usually called ungual. 
The thumb has but two phalanges, the second phalanx taking 
the place of the characteristic ungual or third. 
The first phalanx is the longer, and its shaft is semi-cylindri- 
cal. The posterior surface is convex both from above down- 
ward and from side to side and is smooth. The anterior sur- 
face is slightly curved longitudinally, and is broader above than 
below. The two lateral borders, well-marked above, terminate 
in slight tubercles at the lower aspect of the bone. 
The base, or upper extremity, presents a smooth round shal- 
low articular facet, whose transverse diameter is slightly greater 
than the antero-posterior, and it is almost cup-shaped. This 
is for articulation with the head of the metacarpal bone. 
The head, or lower extremity, presents an antero-posterior 
groove, surmounted on either side by an articular ridge, con- 
stituting a trochlear surface. On either side of the head is a 
slight depression, marked in front and behind by trifling eleva- 
tions or tubercles. 
The second phalanx presents on its base a receiving surface 
for the trochlea; that is, a central ridge with lateral depres- 
sions to receive the corresponding elevations. Like the first 
phalanx it is broad and expanded above, narrower below. Its 
lower extremity presents a trochlea for articulation with the OSTEOLOGY. 
43 
third, or ungual phalanx. The second phalanx, with the excep- 
tion of the head, is like the first, only it is shorter and less 
massive. 
The third, or ungual phalanx (L. unguis, a nail) presents on 
its base an articular surface to receive the trochlea of the sec- 
ond. It then becomes rapidly narrow; but just before it ter- 
minates, it expands into a broadened surface. The bone is 
smooth on its posterior, but rough, prominent and flat on its 
anterior surface. The posterior aspect of this phalanx sup- 
ports the nail, while the anterior surface supports the tissues 
which form the pulp of the corresponding fingers. There be- 
ing but two phalangeal bones for the thumb, the second phalanx 
for the thumb corresponds to the ungual phalanx for the other 
fingers. 
The Skeleton of the Lower Extremity. 
The skeleton of the lower extremity consists of the skele- 
ton of the hip, thigh, leg and foot. 
Os Innominatum (Os Coxae). 
The OS INNOMINATUM (L. un-named bone) haunch bone, is 
the most important bone in forming the pelvic cavity, and cor- 
responds to the scapula in the upper extremity. In the foetus 
it consists of three bones-Ilium, Ischium and Pubis, and, since 
the bone is very irregular in outline, this division has been re- 
tained in describing the bone in the adult. 
The ilium (deriv. uncertain), or flank bone, is the large, ex- 
panded, upper portion of the bone. It is divided for study into 
an internal and external surface, anterior, posterior, and su- 
perior borders, the latter being known as the crest. 
The crest of the ilium (cristailiaca) is sinuous in outline. 
Viewed from the front and outer aspect it is seen to be convex 
for its anterior four-fifths, concave for its posterior one-fifth. 
In front and behind it terminates in rough projections, known 
as the anterior and posterior superior spinous processes. The 44 
DESCRIPTIVE ANATOMY. 
crest consists of two lips, external and internal, and a rough 
intervening space or middle lip. 
The anterior border consists of two projections, anterior su- 
perior and anterior inferior spinous processes, with a notch 
between. The superior is more prominent, but less massive 
than the inferior. Below the inferior is a slight groove sepa- 
rating it from the margin of the acetabulum. 
The posterior border is less regular in form than the anterior, 
and like it, is marked by two projections with an intervening 
notch. These are called the posterior superior and posterior in- 
ferior spinous processes. They are sharper, but less prominent, 
than those on the anterior border, and the notch between is not 
so deep. Below the posterior inferior spinous process is a deep 
notch, part of which is found on the ilium and the remainder 
on the ischium, called the greater sacro-sciatic notch (incisura 
ischiadica major). 
The external surface is curved in outline, being concave for 
the posterior four-fifths, convex for the anterior one-fifth. On 
the posterior border is a deep notch, called great sciatic, and 
commencing in this notch, and curving forward and upward 
from it, are three lines distinguished as superior, inferior and 
middle. The superior curved line (linea glutaea posterior), the 
shortest and most distinct of the three, begins near the upper 
margin of the sciatic notch and passes upward and slightly for- 
ward until it reaches the crest near its posterior one-fifth. The 
middle (linea glutaea anterior), which is the longest, begins at 
the middle of the sciatic notch and passes upward and for- 
ward, markedly curved, to terminate just above the anterior 
superior spinous process. The inferior (linea glutaea inferior), 
the least distinct, starts at the lower portion of the notch, and, 
passing forward and slightly upward, reaches the anterior 
border of the bone a little above the anterior inferior spinous 
process. The whole surface is roughened for the attachment 
of muscles and presents the orifices of numerous foramina for 
the transmission of blood vessels, the largest of which is found 
near the middle of the bone just below the middle curved line. 
The internal surface, much smoother than the external, is con- 
cave for its anterior two-thirds both from downward and from OSTEOLOGY. 
45 
before backward, forming the iliac fossa. Just before the bone 
unites with the ischium it is crossed by a smooth, elevated ridge 
which forms a part of the ilio-pectineal line (linea terminalis). 
The portion of bone below this is smooth, nearly flat, continuous 
with the inclined plane of the ischium, and enters into the for- 
mation of the true pelvis. The posterior one-third of the in- 
ternal surface is very irregular in outline. In front this por- 
tion is occupied by a rough, ear-shaped articular surface (facies 
auricularis) which articulates with a similar surface on the 
sacrum. Behind this is a rough surface, made up of interven- 
ing elevations and depressions for the attachment of ligament- 
ous fibres. 
The ischium (os ischii) is the lower, massive portion of the 
bone. It is divided for study into a body, tuberosity and ramus. 
The body is triangular, and presents for examination three 
surfaces and three borders. The surfaces are internal, external 
and posterior; the borders, anterior, posterior and external. 
The external surface is almost entirely occupied by the ar- 
ticular surface furnished by the ischium to the acetabulum; but 
a small portion below the rim of the acetabulum is occupied by 
a groove, the lower border of which is the mark of division 
between the outer surface and the tuberosity. 
The internal surface slopes obliquely from above downward 
and inward, facing inward and backward. It is smooth and 
concave from before backward and continuous above with a 
similar surface on the inner face of the ilium. 
The posterior surface is quadrilateral, forms the posterior 
wall of the acetabulum and is roughened for muscular attach- 
ment. 
The anterior border is thin and sharp, slopes upward and for- 
ward to join the pubes and forms the posterior boundary of the 
thyroid foramen. 
The external border is thick and rounded and forms the pos- 
terior part of the rim of the acetabulum. 
The posterior border is long and sharp, nearly vertical in 
direction, and is interrupted a little below the middle by a 
prominent projection of bone called the spine of the ischium. 
Above the spine a deep notch is found which enters into the 46 
DESCRIPTIVE ANATOMY. 
formation of the great sacro-sciatic notch, (incisura ischiadica 
major) ; below the spine a similar, but shallower notch, forms 
the lessor sacro-sciatic notch (incisura ischiadica minor). 
The tuberosity is the rough lower end of the bone on which 
the body rests when in the sitting posture. It has an inferior 
surface which is rough and triangular, and just above this, a 
smooth portion, divided into two by an oblique ridge, the parts 
above and below the ridge being intended for muscular attach- 
ment. Internally it presents a rough, prominent ridge which 
separates the lower surface from the internal, and above this 
ridge a smooth groove. 
The ramus passes forward, inward and slightly upward. One 
surface looks outward and forward, the other inward and back- 
ward. One border looks outward and forms the anterior bound- 
ary of the obturator foramen, the other looks inward and forms, 
with the ramus of the pubis, the outer boundary of the pubic 
arch. This internal border is thick and divided into two lips 
and an intervening space. The two lips pass downward to be- 
come continuous with similar lips on the lower surface of the 
tuberosity. The internal border is averted, its upper part look- 
ing nearly forward. At the junction of the ramus of the 
ischium with that of the pubes there is sometimes seen a rough 
line. 
The os pubis (L. Pubes, hair, or down) is divided for study 
into a body and a ramus. The body is the horizontal portion 
of the bone, and is divided into two surfaces, anterior and pos- 
terior, two borders, upper and lower, and two extremities, in- 
ternal and external. 
The posterior surface is concave from within outward, con- 
vex from above downward, and smooth. 
The anterior surface is convex or flat from within outward, 
slightly concave from above downward, broad at its inner and 
narrow at its outer extremity, and rough for muscular attach- 
ments. 
The superior border forms, at its junction with the internal 
extremity, the angle of the pubis; external to this and running 
outward and forward is a rough ridge called the crest. The 
crest terminates after a course of about three-fourths of an OSTEOLOGY. 
47 
inch in a prominent projection of bone called the spine (tuber- 
culum pubicum). Running outward and backward from the 
spine and separating the superior border from the posterior 
surface, is a sharp ridge of bone called the pectineal line (pec- 
ten ossis pubis) ; in front of which is a triangular surface, 
limited in front by the anterior surface of the pubis, the pec- 
tineal triangle. The base of the triangle, which is directed out- 
ward, terminates in a rough prominence known as the pectineal 
eminence. 
The inferior border forms the superior boundary of the ob- 
turator foramen and is marked by an oblique groove, (sulcus 
obturatorius), which, from within the pelvis, extends forward 
and inward. 
The internal extremity, called the symphysis pubis, is an 
oval, rough articular surface, the long diameter of which is di- 
rected from above downward and backward. It is covered by 
a series of nipple-shaped projections and in the recent state is 
lined with cartilage. 
The external extremity is in part attached to the ilium, while 
the remainder is free and enters into the formation of the 
acetabulum. 
The ramus of the pubes is short and extends downward and 
slightly outward. Its surfaces look backward and forward, its 
borders inward and outward. The inner border presents two 
lips and an intervening space, the two lips being continuous 
with those found on the ramus of the ischium. 
The acetabulum (L. vessel for holding vinegar) is a nearly 
circular, cup-shaped cavity, one-fifth of which is contributed by 
the pubes, a little less than two fifths by the ilium, and a little 
more than two-fifths by the ischium. It is articular around the 
whole of its circumference except a small portion at the lower 
and inner part, where a deep notch interrupts the prominent 
rim which elsewhere surrounds the cavity. This notch, called 
the cotyloid, leads to a deep non-articular depression in the bot- 
tom of the cavity, which in the recent state lodges a mass of 
fat and, with its margins, gives attachment to the ligamentum 
teres. 48 
DESCRIPTIVE ANATOMY. 
The thyroid or obturator foramen is found below and in 
front of the acetabulum. It is irregularly oval in outline and 
its boundaries are formed as follows: Behind by the anterior 
border of the body of the ischium, in front by the outer border 
of the ischio-pubic ramus, above by the lower border of the body 
of the pubes, the groove on that bone furnishing nearly the 
whole of the upper boundary. 
Pelvis. 
The pelvic girdle is far more powerful than the shoulder 
girdle, the individual bones being more massive and bound 
more firmly to one another. The cavity has been divided by 
the ilio-pectineal line (linea terminalis) into the true and the 
false pelvis, though the latter term should not be used, since the 
false pelvis is simply a part of the abdominal cavity. 
The pelvis (L. a basin or laver) is the cavity circumscribed 
by the sacrum, coccyx and two ossa innominata, containing in 
the living subject some of the small intestine, a part of the large 
intestine, and the genito-urinary apparatus, in part. It is 
bounded behind by the sacrum and coccyx and throughout the 
rest of its extent by the ossa innominata. It is divided into two 
portions, the false pelvis (pelvis major) and the true (pelvis 
minor). The false pelvis is that portion between the two iliac 
fossae bounded behind by the junction of 5th lumbar and sa- 
crum, while in front it has no bony wall. It extends from the 
crest of the ilium above to the pectineal line below. This pecti- 
neal line, also called linea ilio-pectinea, (linea terminalis), is a 
prominent ridge extending around the os innominatum from the 
symphysis pubis to the sacro-iliac symphysis. At the linea ilio- 
pectinea the pelvis is suddenly contracted and the true pelvis 
begins. The plane circumscribed by the ilio-pectineal line is 
called the brim or inlet of the pelvis, or superior strait of the 
pelvis (apertura superior). The true pelvis thus extends from 
this brim downward to what is called the outlet, or inferior 
strait of the pelvis (apertura inferior). The outlet is limited 
in front by the lower end of the symphysis pubis; the arch 
formed by the divergence of the pubic rami being called the OSTEOLOGY. 
49 
pubic, or sub-pubic arch. Behind, the outlet is limited by the 
tip of the coccyx. Laterally the outlet is bounded by the tuber 
ischii. The pelvis is so attached to the vertebral column as to 
make the plane of the inlet slope obliquely from behind down- 
ward and forward, and so great is this obliquity that the top 
of the symphysis pubis is about four inches below the level of 
the promontory of the sacrum. The so-called axis of the su- 
perior strait is an imaginary line, perpendicular to the plane 
of the brim and cutting it at its centre. The true pelvis is much 
deeper behind than in front, measuring posteriorly five inches, 
laterally three and one-half inches, and at the pubes one and 
one-half inches. Besides these measurements, obstetricians em- 
ploy others, at the outlet and inlet, called diameters. The di- 
ameters usually given are antero-posterior, transverse and 
oblique. 
The average diameters as given by Cunningham are: 
Inlet. Outlet. 
Males. Females. Males. Females. 
Antero-posterior 4 4% 3% 4^ 
Transverse 4% 5 31/9 4^ 
Oblique 5 5%, 3i/2 4% 
The objects observable on the exterior of the pelvis are as 
follows: in front the symphysis pubis and below this the pubic 
arch; on either side the obturator foramen, farther out the 
acetabulum; behind this the greater and lesser sciatic notches, 
separated by the ischiatic spine; on the centre behind are the 
sacral spines. 
The pelvis differs in the two sexes; the characteristic points 
in the female are as follows: 1st, the thyroid foramen is more 
distinctly triangular; 2nd, the pelvis is more capacious-meas- 
uring more transversely and antero-posteriorly, but less verti- 
cally; 3rd, the angle of the pubic arch is greater by 10°, measur- 
ing from 90° to 100°. 
The pelvis in the negro is observedly smaller than in the Cau- 
casian. 50 
DESCRIPTIVE ANATOMY. 
The Femur. 
The femur (L. Femur, the thigh) is the longest and most 
powerful bone in the body. It is divided for study into a shaft 
and two extremities. 
The upper extremity consists of the head, neck and two tro- 
chanters. 
The head (caput femoris), smooth and globular, projects up- 
ward, inward and forward from the neck, and forms about two- 
thirds of a sphere. It is marked a little below and behind its 
centre by a deep pit (fovea capitis femoris) which in the recent 
state lodges the outer end of the ligamentuin teres. 
The neck slopes downward, outward and backward from the 
head, is flattened from before backward and is divided into an 
anterior and posterior surface, an upper and a lower border. 
The anterior surface is flat and slightly roughened; the pos- 
terior, convex from above downward, concave from within out- 
ward, is smooth and rounded. 
The upper border, only one-half the length of the lower, is 
broad, round, thicker than the lower, and marked at its outer 
extremity by a deep pit called the digital. It is nearly straight. 
The lower border is thinner, longer and more oblique than the 
upper. Below and behind it terminates at the lesser trochanter, 
while the upper terminates at the greater trochanter. 
The great trochanter is a quadrilateral piece of bone which 
projects upward from the junction of the neck and shaft. Its 
outer surface is marked by an oblique ridge, a diagonal, run- 
ning from the postero-superior angle to the antero-inferior 
angle. The surface in front of the diagonal is rough, that be- 
hind it is smooth. The inner surface is taken up almost entirely 
by the digital pit. The anterior border is thick and rough, the 
posterior thinner and rounded, the upper thin and rather sharp, 
terminating posteriorly in a blunt projection which overhangs 
the digital pit. 
The lesser trochanter is much smaller than the greater, pro- 
jects from the inner posterior aspect of the bone, is round in 
form, bluntly pointed at its apex and marked by a single muscu- 
lar impression for the attachment of the biceps flexor femoris. OSTEOLOGY. 
51 
Extending from the back of the base of the great trochanter 
downward and inward to the lesser is a roughened ridge of bone 
known as the posterior inter-trochanteric line. On the anterior 
aspect, and starting from the base of the great trochanter, there 
is a prominent line which winds around the bone, passing down- 
ward and inward until it reaches the inner face of the bone when 
it turns and runs outward, called the spiral line of the femur. 
This line is sometimes incorrectly called the anterior inter- 
trochanteric line. It passes about half an inch below the lesser 
trochanter. 
The lower extremity of the femur is flattened from before 
backward, so that the lateral diameter exceeds the antero-pos- 
terior. It consists of two round or oval articular surfaces, 
called condyles, two rough projections, one on either side, called 
tuberosities, and an intervening notch, If the bone is held ver- 
tically it will be seen that the inner condyle (condylus medialis) 
is prolonged downward considerably below the outer to com- 
pensate for the obliquity of the bone caused by the width of the 
pelvis, which separates the heads of the bone, while the lower 
extremities approach each other. The long diameter of the ar- 
ticular surface of each condyle is from before backward; but 
it will be seen upon careful examination that the inner condyle 
is longer and narrower than the outer, that its articular surface 
extends higher up behind and not so high in front. The outey' 
condyle (condylus lateralis) is more circular, is shorter than the 
inner, its articular surface extending higher up in front than 
behind. The two condyles are separated behind by a deep and 
roughened notch, called the intercondyloid notch (fossa inter 
condyloidea). This notch is marked on either side by a depres- 
sion for the attachment of the corresponding crucial ligaments 
of the knee-joint. In front this notch is continuous with a 
smooth articular surface, concave from side to side, convex from 
above downward, and forms a trochlea for the opposing surface 
of the patella (facies patellaris). Each condyle presents an 
internal and an external surface. The external surface of the 
external condyle is marked by a prominent rough tuberosity 
called the outer tuberosity of the femur (epicondylus lateralis) ; 
and below this is an antero-posterior groove for muscular at- 52 
DESCRIPTIVE ANATOMY. 
tachments. The internal surface of the external condyle is the 
outer boundary of the intercondyloid notch. The internal sur- 
face of the internal condyle is likewise marked by a rough pro- 
jection, called the internal tuberosity of the femur (epicondylus 
medialis); while the outer surface of the internal condyle is the 
inner boundary of the intercondyloid notch. The inner surface 
of the inner and the outer surface of the outer condyles are each 
marked by nutrient foramina. Above each condyle is seen a 
slight depression on the posterior aspect of the bone, which is 
intended for the attachment of the gastrocnemius muscle. Lead- 
ing upward from behind either condyle is a ridge. These ridges 
approach each other above to reach the linea aspera. They are 
known as the supra condyloid ridges, and more properly belong 
to the shaft of the bone. Between these ridges is a triangular 
smooth space called the popliteal triangle (planum popliteum). 
The shaft of the femur. Like most long bones the femur is 
triangular upon cross-section, and therefore presents for study 
three surfaces and three borders. The surfaces are anterior 
and two lateral, while the borders are posterior and two lateral. 
The anterior surface is round, convex from above downward, 
so that the bone is bowed in outline, with its convexity forward, 
convex from side to side, and broader above and below than in 
the middle. 
Of the two lateral surfaces, the external is slightly concave 
from above downward, and smooth; the internal also slightly 
concave from above downward, broader than the external, and 
smooth. The lateral borders are indistinctly marked. 
The external lateral, commencing at the base of the trochanter 
major, extends, indistinctly marked, down to the outer tuber- 
osity of the femur. 
The internal lateral, commencing at the spinal line of the fe- 
mur, passes downward to the inner tuberosity. 
The posterior border, called linea aspera, is the most distinct 
of the three. It may be considered as consisting of a central 
portion, called the "body," and an upper and a lower portion. 
The central portion, or body, occupies about the middle two- 
fourths of the bone. It presents an internal (labium mediale) 
and an external (labium laterale) lip, and a rough intervening OSTEOLOGY. 
53 
space, which are intended for muscular attachments. Above it 
divides into three lines: one, labium mediale, winds around 
about a quarter of an inch below the lesser trochanter to become 
continuous with the spiral line of the femur; one passes up- 
ward to the base of the lesser trochanter; while the third, la- 
bium laterale, passes upward and outward to join the posterior 
border of the greater trochanter. Below it subdivides into two 
ridges, which are known as the two supra condyloid ridges. 
These two ridges diverge from each other, enclosing the pop- 
liteal space, a smooth triangular space found at the lower ex- 
tremity of the shaft, the base of which is directed downward to 
the condyles and the apex upward to the linea aspera. Of these 
two lines the external is the more distinct, the internal being 
obliterated near its middle by the groove which transmits the 
femoral artery. About the middle of the shaft of the bone, 
more frequently above than below, in the linea aspera, though 
occasionally on the inner surface close to the linea aspera, is 
found a large nutrient foramen, which is directed obliquely 
upward and outward. 
The Patella. 
The patella (L. Patella, a small pan), or knee-pan, is a sesa- 
moid bone situated on the front of the knee joint, developed in 
the tendon of the triceps extensor cruris. It presents for ex- 
amination two surfaces, anterior and posterior, two extremities, 
superior and inferior, and two borders, internal and external. 
The anterior surface is rough, convex from side to side and 
slightly so from above downward, marked by a number of ver- 
tical lines and a number of nutrient foramina. 
The posterior surface is smooth and articular. Near its mid- 
dle it presents a prominent vertical articular ridge; and on 
either side of this a depression, also articular, intended for the 
reception of the condyles of the femur. The posterior face 
forms the receiving surface for the trochlea. These depres- 
sions are dissimilar in size and shape; and correspond to the 
dissimilarity of the condyles of the femur, the outer depression 
being larger and more nearly circular, while the inner is smaller 54 
DESCRIPTIVE ANATOMY. 
and more oval in outline. Below the articular surface is a rough, 
pitlike depression, near the inferior extremity, for ligamentous 
attachment. 
The upper extremity (basis patellae) of the bone is blunt, 
rough, and marked by a transverse ridge; the lower extremity 
(apex patellae) is smaller, more pointed, and roughened. 
Of the borders, the external is thinner and sharper than the 
internal. Both are roughened for the attachment of the tendi- 
nous fibres of the triceps. 
The Tibia. 
The tibia (L. tibia, flute or pipe) is a long bone, consisting of 
a shaft and two extremities. It is the larger of the two bones 
making up the skeleton of the leg. 
The upper extremity is expanded so that its transverse di- 
ameter is much greater than its antero-posterior. It presents 
upon its summit two shallow articular cavities, called glenoid 
cavities, intended to receive the condyles of the femur, which 
are, in correspondence with them, dissimilar in shape, the outer 
being circular and the inner oval. The inner cavity has its 
long diameter, from before backward; the outer cavity is shal- 
lower, as well as being circular in outline. These cavities are 
separated from one another by a prominent projection, which is 
called the spine (eminentia intercondyloidea) of the tibia. This 
spine is bifurcated, and is situated nearer to the posterior than 
to the anterior surface of the extremity. In front and behind 
the spine is seen a roughened, non-articular space, which is in- 
tended for ligamentous attachment. On the front of the bone, 
extending about an inch below the articular cavities, is a rough 
triangular space, terminating in a projection called the anterior 
tubercle (tuberositas tibia) of the tibia. This tubercle is smooth 
above and rough below, the roughened lower portion being in- 
tended for muscular attachment. The expanded portion of the 
bone upon which the glenoid cavities rest forms the tuberosities 
of the tibia, internal and external. The internal tuberosity (con- 
dylus medialis), somewhat more prominent than the external, 
is rough, and marked near its posterior portion by a deep trans- OSTEOLOGY. 
55 
verse, or antero-posterior groove. The external tuberosity (con- 
dylus lateralis) is roughened, as is the internal, and posteriorly 
is marked by a flat, circular, articular facet, which is directed 
downward, outward, and backward, and is intended for articu- 
lation with the upper extremity of the fibula. Behind, the 
tuberosities are both roughened for ligamentous attachment. 
The lower extremity is four-sided, and is about half the size 
of the upper. On its inner side there extends downward a rough 
projection of bone, called the internal malleolus (L. a small mal- 
let) . It corresponds nearly to a styloid process. 
The internal malleolus (malleolus medialis) presents two sur- 
faces, two borders, and an extremity. Of the surfaces, the in- 
ternal is rough, and subcutaneous, while the external is smooth 
triangular and articular, entering into the formation of a cavity 
found upon the extremity of the tibia for articulation with one 
of the bones of the tarsus. The anterior border of the malleolus 
is shorter than the posterior, and is vertical in its direction, 
while the longer posterior border is oblique, extending down- 
ward and forward, and has upon it a well-marked groove (sul- 
cus malleolaris) for the transmission of a tendon. The ex- 
tremity is blunt, and is marked by a pit-like depression. 
On the outer surface of the lower extremity is a transverse 
depression (incisura fibularis), sometimes articular, more gen- 
erally roughened, which receives the lower extremity of the 
fibula. The long diameter of this depression is directed from 
before backward; and leading upward from it are two lines, 
which shortly converge, enclosing between them a rough tri- 
angular space for the attachment of interosseous ligaments. 
The anterior aspect of the lower extremity is roughened for 
ligamentous attachment, while the posterior, also roughened, is 
marked by a vertical groove. 
The summit presents an articular facet, the tarsal cavity, 
continuous with the one on the outer face of the internal mal- 
leolus, and intended for articulation with the upper surface of 
the astragalus. This facet is broader externally than intern- 
ally, and broader in front than behind. Its contour presents 
a generally concave surface from before backward, which is ele- DESCRIPTIVE ANATOMY. 
56 
vated into a slight central antero-posterior ridge. From side 
to side it is nearly flat, except where the ridge is seen. 
The shaft of the bone is three-sided, presenting an internal, 
an external, and a posterior surface, and an anterior and two 
lateral borders. The bone is generally somewhat twisted, par- 
ticularly in the negro race; and is bowed, convex internally and 
concave externally. 
The internal surface (facies medialis) is broad above, becom- 
ing slightly narrow below; is convex both from above dowm- 
ward, and from before backward, and is subcutaneous. It is 
continuous below with the inner face of the internal malleolus. 
The external face (facies lateralis), which is concave from 
above downward, is marked by a vertical groove close to the 
external border of the bone. This face in the lower third curves 
gradually forward to become anterior. 
The posterior face (facies posterior) is broad and flat for the 
upper one-fifth of the bone, becoming more rounded in the mid- 
dle and flatter and broader in the lower portion. At its upper 
part it is marked by an oblique ridge, called the popliteal line, 
which extends downward and inward from the external tuber- 
osity of the bone. The space above this line is the popliteal 
triangle of the tibia. Below this ridge the posterior surface is 
marked about its middle by a vertical ridge, which exists only 
for about the middle of the bone, disappearing in the lower 
portion. Near the commencement of the vertical ridge, gen- 
erally on the posterior surface, is found a large nutrient fora- 
men, being in fact the largest in the body, which conveys the 
blood to the interior of the bone. In the negro race the surface 
above the popliteal line is rarely as flat as in Caucasians. The 
popliteal triangle and line are generally poorly marked. 
The anterior border (crista anterior), or shin, is very sharp 
and very prominent. It is sinuous in outline, more distinct in 
the upper two-thirds of the bone, while in the lower third it 
passes to the front of the internal malleolus and blends with the 
anterior border of this projection. It begins above at the an- 
terior tubercle. OSTEOLOGY. 
57 
The internal border (margo medialis), separating the inter- 
nal from the posterior surface, begins as an indistinct line at 
the inner tuberosity, becomes more prominent about the middle 
of the bone, and finally passes to the posterior border of the 
internal malleolus. 
The external border (crista interossea) commences above at 
the outer malleolus, in front of the articular facet for the fibula. 
It is the interosseous border. It is indistinct above, well marked 
in the middle portion of the bone, and at the lower extremity 
divides into two lines, which form the boundaries of the tri- 
angular space mentioned as being on the lower extremity of the 
bone. 
The Fibula. 
The fibula (L. fibula, a clasp) is the outer and more slender 
of the two bones forming the skeleton of the leg. It is a long 
bone, having of course a shaft and two extremities. 
The upper extremity (capitulum), or head, is club-like in out- 
line, and presents on its upper inner aspect an articular facet, 
the contour of which varies in different bones. It is circular in 
form, usually slightly concave, but may be flat, and looks up- 
ward, forward and inward. It is intended for articulation with 
a similar facet on the outer tuberosity of the tibia. The outer 
aspect of this extremity is roughened for muscular and liga- 
mentous attachment, and terminates above in a blunt projec- 
tion called the styloid process of the fibula (apex capituli fibulae). 
The lower extremity is usually spoken of as the external mal- 
leolus (malleolus lateralis). It is larger and more pointed than 
the upper and is indistinctly triangular. It may be described 
as consisting of internal and external surfaces, anterior and pos- 
terior borders, and an apex. The outer surface is prominent, 
convex, rough and subcutaneous. The internal surface is ar- 
ticular through a part of its extent; and both above and below 
the articular surface is found a roughened space-that above 
for the interosseous ligaments which attach it to the tibia, that 
below for ligamentous fibres binding it to the bones of the foot. 58 
DESCRIPTIVE ANATOMY. 
The articular space is pear-shaped, with the large end upward, 
and is intended for the lateral aspect of the astragalus, and 
occasionally extends upward to articulate with the tibia. Be- 
low and behind the articular facet is a rough depression for liga- 
mentous attachment. The posterior border is nearly straight, 
is much thicker than the anterior border, and is marked by a 
shallow groove for the passage of a tendon. The anterior 
border is narrow and convex, and slopes obliquely from above 
downward and backward. The apex is a blunt, roughened point. 
The shaft of the bone is twisted, presenting what is known 
as the curve of torsion, so that its faces and borders change their 
relative positions in the different portions of the bone. The 
faces may be described as external, internal, and posterior. 
The external face, narrow and convex above, becomes broader 
about the middle of the bone, and owing to the twisting of the 
bone becomes posterior at its lower one-third. 
The internal face, slightly curved above, marked by a ridge 
over the central portion of the bone, twists at the lower third 
to become anterior. 
The posterior face, narrow and convex above, broader and 
still convex at the centre, becomes flat and internal at the lower 
one-third of the bone. 
The anterior border is slightly marked above, prominent in 
the middle of the bone, divides into two lines at the lower one- 
third, one of which becomes external and passes to the middle 
of the external malleolus, while the other, more slightly marked, 
passes to the anterior border of the external malleolus, leaving 
between them a triangular space, which is a continuation of the 
internal surface. 
The external border, commencing at the head of the bone, 
much more slightly marked than the internal border, becomes 
more prominent in the lower third of its course, and passes to 
the back of the external malleolus. 
The internal border commences at the back of the head of the 
fibula, is joined by the interosseous ridge in the middle of the 
bone, runs down upon the internal face, and twists to the front 
of the bone in the lower portion of its course. OSTEOLOGY. 
59 
The Foot. 
The foot bears a strong resemblance to the hand, differing 
essentially from it, however, in that it is at right angles to the 
leg, and, consequently, its surfaces are superior and inferior, 
instead of anterior and posterior. It consists of an irregular 
set of bones forming the Tarsus (ossa tarsi), a set of long 
bones forming the Metatarsus (ossa metatarsalia) and the 
Phalanges. 
The Tarsus. 
The tarsus consists of seven bones: The os calcis, astragalus, 
scaphoid, cuboid, and three cuneiform bones, known as external, 
middle, and internal, or, sometimes as first, second, and third. 
These bones are arranged in two rows: the first row, or pos- 
terior row, consisting of the os calcis and astragalus, the re- 
maining five bones forming the second row. 
The Bones of the First Row (Calcaneus). 
The OS calcis (L. Calx, the heel), forms the posterior 
abutment of the arch of the foot, and is known as the 
heel bone. It presents for examination two extremities, an- 
terior and posterior, and four surfaces, superior, inferior, and 
two lateral. 
The upper surface consists of two portions, one behind the 
other. The posterior part of the upper surface is roughened; 
marked by the presence of a few nutrient foramina, and is non- 
articular. It is convex from side to side. The anterior portion 
presents two articular surfaces, separated by an oblique groove. 
Of these surfaces, the larger and more posterior is convex in 
outline, and oblique in direction. Its long diameter is directed 
from behind forward and outward, and it corresponds to the 
concave receiving cavity on the inferior surfaces of the astra- 
galus. The anterior is an oblong articular facet, concave from 
behind forward and outward, the direction of its long diameter, 
and intended for the reception of the convex articular facet on 60 
DESCRIPTIVE ANATOMY. 
the lower surface of the astragalus. The groove which sepa- 
rates the two surfaces is called the sulcus calcanei (L. the fur- 
row of the heel), and is directed like the surfaces, that is, for- 
ward and outward. 
The inferior surface is rough, narrow, and non-articular, and 
presents near its posterior extremity two tuberosities, of which 
the internal (processus medialis tuberis calcanei) is larger. 
The anterior part of the inferior surface is hardly more than 
a rough and rounded border. 
The external surface is convex throughout its course, is very 
rough for the attachment of ligaments, and is marked by two 
grooves, one above the other, separated by a slight roughened 
ridge. These grooves are intended for the transmission of ten- 
dons. 
The internal surface is deeply concave, and is overhung in 
its anterior portion by a projection of bone, which is called the 
sustentaculum tali (L. a support for the ankle), or lesser pro- 
cess of the os calcis. The deep concavity on the internal sur- 
face is caused mainly by this projection of bone, which is 
grooved on its under surface for the transmission of a tendon, 
and which bears on its upper surface the greater portion of the 
anterior one of the two facets on the superior face of the bone. 
The posterior extremity (tuber calcanei) is quadrilateral in 
outline, rough at its lower portion, smooth above for the play 
of the bursa between itself and the tendon of Achilles. 
The anterior extremity (great process) is concavo-convex, 
forming a saddle-shaped articulation between this bone and the 
cuboid. This surface is concave from above downward and out- 
ward, convex in the opposite direction. 
Astragalus (Talus). 
The astragalus, the second bone of the first row, lies be- 
tween the tibia above, the two malleoli at the sides, and the 
scaphoid in front. It presents like the os calcis four surfaces 
and two extremities, the surfaces, as is the case with the os 
calcis, being superior, inferior, and two lateral, while the ex- 
tremities are anterior and posterior. OSTEOLOGY. 
61 
The superior sztrface is divided into two portions, a posterior 
articular portion, and an anterior, frequently called the "neck" 
of the bone, which is non-articular. The articular portion troch- 
lea tali) is narrow behind and broad in front, a fact which 
governs some of the movements of the ankle-joint. It is com- 
posed of a central depression with two elevated ridges, one 
upon either side, or in other words, it is a trochlea. 
The inferior surface is in the main articular, consisting of 
two facets. The posterior facet is quadrilateral and concave, 
its long diameter directed forward and outward, and corre- 
sponds to the posterior of the two facets on the upper surface 
of the os calcis. The anterior articular facet is convex. Its 
long diameter likewise is directed forward and outward, and it 
corresponds to the concave facet on the os calcis. Between these 
two articular surfaces is a deep oblique groove, running for- 
ward and outward, which is called the sulcus tali. This sulcus 
corresponds in position to the sulcus calcanei, and when the 
two bones are articulated, the junction of the two sulci forms 
a canal, which is known as the sinus tarsi. 
The internal face is articular to a small extent, that is, at the 
junction of the internal and superior faces is found an oblong 
articular facet, its long diameter directed from before backward, 
continuous with the articular surface on the superior face of 
the bone, and intended for articulation with the internal mal- 
leolus. Below this articular facet is a rough depression for liga- 
mentous attachment, and the remainder of the internal surface 
is likewise roughened. 
The external surface is triangular, or pyriform, the base up- 
ward and apex downward. It is concave from above downward, 
slightly convex from before backward, and is continuous with 
the articular facet on the superior surface of the bone. It is 
intended for articulation with the external malleolus. Below 
the articular surface is a slight roughness for ligamentous at- 
tachment. 
The anterior extremity, or head (caput tali) of the bone, is 
oval, convex, and articular; the long diameter of the head, 
slightly oblique in direction, is from above downward and in- 
ward, and is intended for articulation with the cavity found 62 
DESCRIPTIVE ANATOMY. 
upon the scaphoid. This head is supported upon a constricted 
portion of the bone, sometimes called the "neck," a part of 
which has been already seen as a roughened surface, in front 
of the articular facet. The remaining portion of the neck is 
rough and thick. 
The posterior extremity is hardly more than a narrow border. 
It is marked by a slight transverse groove just behind the su- 
perior articular surface, and by an oblique groove, which ex- 
tends downward and inward, and is continuous in the articu- 
lated foot with the concave inner face of the os calcis. 
The Bones of the Second Row. 
The Cuboid (Os Cuboideum). 
The CUBOID lies between the os calcis behind, the scaphoid and 
external cuneiform to its inner side, and the fourth and fifth 
metatarsal bones in front. It presents four surfaces, superior, 
inferior, external, and internal, and an anterior and a posterior 
extremity. 
The upper surface looks upward and outward, and is rough 
and irregular for the attachment of ligaments. 
The inferior surface is very irregular in outline. A little in 
front of the middle it is divided by a prominent ridge, called 
the peroneal ridge, into an anterior portion, which is occupied 
almost entirely by a groove, also called peroneal, and a larger 
posterior portion, which is roughened for ligamentous attach- 
ment. The peroneal ridge terminates externally in the tuber- 
osity, a somewhat rounded blunt projection of bone, which con- 
stitutes one of the landmarks of the foot. 
The internal face near the junction of the inner and superior 
faces is marked by an oblong articular facet, which is intended 
for articulation with the external cuneiform bone. Occasionally 
behind this facet is another smaller facet for articulation with 
the scaphoid, though usually these bones do not articulate with 
one another. Below the articular facet the bone is rough for the 
attachment of the interosseous ligaments. OSTEOLOGY. 
63 
The external face is in reality only a border. It is narrow and 
roughened, presenting the projection of the peroneal ridge and 
the commencement of the peroneal groove. 
The anterior extremity is divided into two articular facets by 
a vertical ridge. The inner of these facets is quadrilateral in 
outline; the external, triangular. They are intended for articu- 
lation with the fourth and fifth metatarsal bones respectively. 
The posterior extremity is concavo-convex, being concave 
from above downward and inward and convex from above down- 
ward and outward, to correspond with a similar articular sur- 
face on the anterior extremity of the os calcis. At the junction 
of the inferior and internal surfaces this extremity is prolonged 
backward and inward, so that the os calcis apparently rests 
partly upon a prolongation of the cuboid. 
The Scaphoid (Os Naviculare Pedis). 
The SCAPHOID, the second bone of this row, presents an an- 
terior posterior, superior, and inferior surface, and internal and 
external extremities. 
The posterior surface is entirely occupied by a concave smooth 
articular facet, whose transverse diameter is greater than its 
vertical, and is intended for articulation with the head of the 
astragalus. 
The anterior surface has three articular facets, separated by 
two slightly-marked vertical ridges. These facets articulate 
with the three cuneiform bones. The most internal, which ap- 
proaches the nearest to the inferior surface of the bone, is large 
and slightly triangular; the central is also triangular, and the 
external, nearly quadrilateral in outline, is oblique in its direc- 
tion. The inner triangular surface has its base downward, 
while the base of the middle facet is upward. 
The superior surface is convex from side to side and rough- 
ened for ligamentous attachment. 
The inferior surface, narrower than the superior, is also 
roughened for ligamentous attachment. 
The inner extremity of the bone (tuberositas ossis navicula- 
ris) is a blunt projection, the tuberosity of the scaphoid which, 64 
DESCRIPTIVE ANATOMY. 
with the tuberosity of the internal cuneiform, furnishes another 
of the landmarks of the foot. 
The outer extremity is usually roughened, but occasionally 
presents a small facet for articulation with the cuboid. 
The Ossa Cuneiforma. 
The Internal Cuneiform. 
The internal cuneiform (os cuneiforme primum), like the 
other two, is irregularly wedge-shaped, and lies on the inner 
side of the tarsus, between the first metatarsal in front, the 
scaphoid behind, and the middle cuneiform, and second meta- 
tarsal to the outer side. It is the largest of the cuneiform 
bones, and unlike all of the others, is broader below than above. 
Its internal face is rough and convex. 
The external face is marked along the junction of the superior, 
external and posterior faces by a reversed L-shaped facet, in- 
tended for articulation with the middle cuneiform. In front of 
this facet is a smaller articular surface for the second metatarsal 
bone. 
The posterior face is concave, slightly triangular in outline, 
with its base downward, corresponding to the internal one of 
the facets upon the scaphoid. 
The anterior face is articular throughout, slightly convex and 
is said to be kidney-shaped. 
The inferior face, or base of the bone, is very rough, and ter- 
minates posteriorly in the blunt elevation or tuberosity of the 
internal cuneiform. 
The superior face is scarcely more than a rough narrow 
border. 
The Middle Cuneiform. 
The middle cuneiform (os cuneiforme secundum) lies be- 
tween the internal cuneiform on its inner, and the external 
cuneiform on its outer side, the scaphoid behind and the second 
metatarsal in front. OSTEOLOGY. 
65 
Its superior surface, much broader than its inferior, is rough 
and irregular for the attachment of ligaments. 
The inferior surface, scarcely more than a border, is also 
roughened. 
The internal surface presents a reversed L-shaped facet 
similar to the one found upon the internal cuneiform. 
The external surface has an articular facet upon its posterior 
portion, but is non-articular in front, being roughened for the 
attachment of the interosseous ligament. 
The posterior surface is smooth, slightly triangular, with its 
base upward for articulation with the middle facet upon the 
scaphoid. The anterior surface is articular, convex slightly 
from side to side for articulation with the base of the second 
metatarsal bone. This bone is more distinctly wedge-shaped 
than the other two cuneiform bones. 
The External Cuneiform. 
The EXTERNAL CUNEIFORM (os cuneiforme tertium) is inter- 
mediate in size between the internal and the middle. It lies 
with the middle cuneiform to its inner, and the cuboid to its 
outer side, the scaphoid behind and the third metatarsal bone 
in front. The bone appears to be slightly bent upon itself, so 
as to be concave internally and convex externally. 
Its superior surface is roughened like the preceding tarsal 
bones. 
Its inferior surface, narrower than the superior, is likewise 
rough for ligamentous attachment. 
The internal surface is slightly concave from before backward, 
and presents an articular facet near its posterior end for articu- 
lation with the middle cuneiform. In front of this facet it is 
roughened for the interosseous ligament. Near the anterior 
extremity is a very slight facet for articulation with the lateral 
aspect of the second metatarsal bone. 
The external surface has an oblong facet near its upper pos- 
terior portion, corresponding to the slight facet which is found 
on the inner face of the cuboid. In front of this the external 
surface is roughened for ligamentous attachment. 66 
DESCRIPTIVE ANATOMY. 
Posteriorly it presents a smooth nearly flat articular facet, 
which is cut obliquely so as to face backward and inward, thus 
distinguishing it from the other cuneiform bones, whose pos- 
terior extremities are cut squarely. 
The anterior surface, or extremity, presents a smooth quad- 
rilateral articular facet for articulation with the third metatar- 
sal bone. 
The Metatarsal Bones. 
The metatarsal bones (ossa metatarsalia) present the same 
general characteristics as the metacarpal. They are long bones, 
presenting a shaft and two extremities. Like the metacarpal 
bones they are five in number, but are numbered from within 
outward. 
A Typical Metatarsal Bone. 
A typical metatarsal BONE presents a posterior extremity, 
or base, an anterior extremity, or head, and a shaft. 
The posterior extremity is quadrilateral in outline, marked by 
an articular facet upon its summit, and an articular facet upon 
each lateral aspect, its superior and inferior surfaces being 
rough and square. 
The head, much smaller than the base, presents on its summit 
an articular facet, which is convex, with its long diameter from 
above downward. Behind the head is a slightly constricted por- 
tion, which is surmounted on each side, near the dorsal aspect 
of the bone, by a well-marked tubercle, while a smaller tubercle 
is found near the plantar aspect. Upon the plantar aspect the 
head is grooved for the transmission of tendons. 
The shaft of the bone is narrow, and presents a dorsal surface 
marked by an indistinct ridge, bifurcating below to extend to 
the two dorsal tubercles. The lateral surfaces are concave, so 
as to leave an interosseous space between the adjoining meta- 
tarsal bones. The lateral borders are rounded and indistinct, 
beginning behind on either side of . the base, and terminating OSTEOLOGY. 
67 
in front at the dorsal tubercles. The inferior border is rounded 
and indistinctly marked. 
The first metatarsal bone is very massive. Its posterior ex- 
tremity presents a concavo-convex articular surface; and its 
anterior extremity, presenting a rounded head, is, unlike the 
other metatarsal bones, nearly as large as the posterior ex- 
tremity. 
The second metatarsal, the longest of the metatarsal bones, 
presents an articular facet on its summit for the middle 
cuneiform, on its inner side an articular facet for the internal 
cuneiform, and on its outer side a well-marked articular facet 
for the third metatarsal, and a somewhat slightly marked facet 
for the external cuneiform. 
The third metatarsal bone presents on its base an articular 
facet on either side, that on the inner side being divided into 
two by an antero-posterior groove. On its summit is an articular 
facet for the external cuneiform bone. 
The fourth metatarsal is the typical metatarsal bone, and 
need be no further described. 
The fifth metatarsal bone has as its peculiar chacteristic a 
blunt projection on the outer side of its base, this projection 
being subcutaneous, and one of the most important landmarks 
of the foot. It has only one lateral articular facet, which is on 
its inner side. 
Certain general characteristics enable us to distinguish be- 
tween the metatarsal and metacarpal bones. The most import- 
ant is that the metatarsal bones are all about the same length, 
but are slenderer than the metacarpal; and whereas in the meta- 
carpal bones the head is always of nearly the same or greater 
size than the base, in the metatarsal bones the base more than 
doubles the size of the head, with the single exception of the 
first metatarsal, which is distinguished by other marks. In 
a metatarsal bone the head and base are flattened laterally, 
while in a metacarpal bone both diameters are about equal. 68 
DESCRIPTIVE ANATOMY. 
The Phalanges. 
The phalanges of the toes, like those of the fingers, are 
arranged in three rows, except that the great toe has, like the 
thumb, but two phalanges, the place of the second being taken 
by the ungual. They resemble those of the hand so closely that 
a separate description is not necessary. They are smaller and 
shorter than those of the hand, the second phalanx particularly 
being scarcely more than a neck of bone separating two articular 
extremities, while the ungual phalanx is frequently scarcely dis- 
tinguishable, except that for the first toe. In the fifth, or little 
toe the ungual and second phalanges are sometimes found ossified 
together. 
The Hyoid Bone. 
The hyoid (os hyoideum), or lingual bone, is placed in the 
upper front part of the neck, at the base of the tongue. It is 
U-shaped, and is placed horizontally, being a symmetrical bone. 
It is an isolated bone, but is connected, on either side, by a liga- 
mentous cord with the styloid process of the temporal bone. Occa- 
sionally this cord becomes ossified, and then the hyoid is con- 
nected by a bony arch with the two temporal bones. The bone is 
divided for study into a body and two cornua, greater and lesser, 
on either side. 
The body (corpus ossis hyoidei) presents two surfaces, an- 
terior and posterior, two borders, superior and inferior, and 
two extremities. 
The anterior surface looks upward and forward and is divided 
by a transverse and a vertical ridge into four rough depressions 
for muscular attachment. The crossing of the ridges forms a 
small tubercle. 
The posterior surface looks downward and backward, is con- 
cave from above downward and from side to side, forming a 
deep recess. 
The superior border is directed backward and upward and 
is rough and rounded. 
The inferior border, directed forward and downward, is pro- 
tuberant, and rough for muscular attachment. OSTEOLOGY. 
69 
The extremities, in early life, are marked for the cartilaginous 
attachment of the cornua, which are ossified in later life. 
The greater cornu (cornu ma jus) projects upward, backward 
and outward from the body. It is largest near the body, 
where it is flattened from side to side, then diminishes in size 
and becomes round, to enlarge at its extremity into a rounded 
nodule. 
The lesser cornu (cornu minus) is, until old age, cartilagi- 
nous. It is a mere hook-like nodule, about a fourth of an inch 
long, projecting upward, backward and slightly outward from 
the junction of the body and greater cornua, where it articulates. 
In advanced life the joint disappears and the lesser cornua is 
ossified to the remainder of the bone. 
The Skeleton of the Head. 
The skeleton of the head, or skull, consists of two portions, 
the bones of the cranium and those of the face. 
Cranium. 
The CRANIUM is the upper division of the skull, and is formed 
by the union of eight bones-Occipital, Frontal, Sphenoid, 
Ethmoid, two Parietal and two Temporal. These become securely 
ossified together in mature life, and can be separated only in the 
young subject. 
Occipital. 
The occipital (os occipitale) bone, sometimes called the first 
cranial vertebra, is situated at the posterior and inferior part 
of the cranium, and presents for examination two surfaces, four 
angles and four borders. 
The posterior surface, frequently erroneously called external, 
is convex, both from side to side and above downward, and 
presents above its centre an eminence called the posterior occi- 
pital protuberance; curving outward from this on either side 
is a rough ridge called the superior curved line (superior nuchal 
line) ; passing downward from the protuberance to a large DESCRIPTIVE ANATOMY. 
70 
aperture-the foramen magnum-is a sharp ridge, the occipital 
crest (median nuchal line) ; arching outward on either side from 
the middle of the crest and concentric with the superior curved 
(nuchal) line is the inferior curved line. The portion between 
the curved lines is slightly depressed and rough. At the lower 
termination of the crest is seen the foramen magnum, a large 
oval opening whose antero-posterior diameter is the longer and 
whose larger end is behind. On either side of the front half of the 
foramen magnum is seen the condyle for articulation with the 
superior articular process of the atlas; it is oval, convex, articu- 
lar, and directed obliquely forward and inward. Just behind the 
condyle is a depression, the posterior condyloid fossa, with 
occasionally a foramen opening into it-the posterior condyloid 
foramen. In front of the condyle is the anterior opening of the 
anterior condyloid foramen. Passing outward from the condyle 
is a rounded elevated ridge, the jugular or transverse process. 
On the inner aspect of the condyle is a tubercle. In front of 
the foramen magnum is the basilar process; it is horizontal, 
quadrilateral, convex from side to side, and presents an antero- 
posterior ridge, the pharyngeal spine. 
The anterior face is concave and presents four ridges, meet- 
ing at right angles, about the middle, called the crucial ridge, 
or occipital cross. Each ridge is called an arm of the cross. 
Three of these ridges are grooved; while the fourth, which is 
the inferior, is sharp and not grooved until it approaches the 
foramen magnum. At the point where the four arms meet there 
is an eminence called the anterior occipital protuberance. The 
depression, situated upon the left half of this eminence, is 
formed by the junction of the superior and lateral sinuses, and 
is known as the torcular Herophilii. Above each lateral arm 
of the cross there is a shallow depression, the cerebral fossa; 
below each lateral arm is another depression, the cerebellar 
fossa. At the termination of the lower arm is the foramen 
magnum, and on each side of this posterior opening of the 
anterior condyloid foramen. On either side of the foramen 
magnum is a smooth broad groove for the termination of the 
lateral sinus. This groove rests on the upper surface of the 
jugular process. In front of the foramen magnum is the basilar OSTEOLOGY. 
71 
process, which, as on its inferior surface, is nearly horizontal 
and quadrilateral, but is here concave to sustain the medulla 
oblongata. The groove for the petrosal sinus marks the lateral 
border of this process. 
The angles are superior, inferior, and two lateral. 
The lateral angles are each situated where the groove in the 
lateral limb of the crucial ridge strikes the border of the bone. 
The inferior angle is the truncated extremity of the basilar 
process, and articulates with the body of the sphenoid. 
The superior angle juts into the interval formed by the union 
of the posterior superior angles of the parietal bones. 
The borders are two superior and two inferior. Each superior 
border is serrated for articulation with the parietal bone, and 
extends from the superior to the lateral angle. 
Each inferior border articulates with the temporal bone, 
mastoid and petrous portions; is serrated and is interrupted 
about its middle by a protuberance, the jugular eminence, in 
front of which is a depression, the jugular fossa. 
Parietal. 
The two parietal (os parietale) bones form the upper and 
most of the lateral wall of the cranium, and are situated be- 
tween the frontal and occipital bones, in front and behind, and 
the two temporal bones laterally. Each bone is divided into 
two surfaces, four borders, and four angles. 
The external surface is convex and presents a decided bulge 
about the middle, the parietal eminence; through this is seen 
running the temporal ridge, arching across this bone from the 
frontal; below the ridge is a nearly flat surface forming part 
of the temporal fossa. Near the posterior superior angle is seen 
the parietal foramen, which is frequently absent. 
The internal surface is mostly concave and is sunken in the 
middle into a fossa. It is marked by digital pits for lodging 
cerebral convolutions, and the arborescent furrows worn by 
the arteries. Along the edge of the superior border is seen 
half of a groove, completed by the opposite bone, and formed 
by the sagittal sinus. 72 
DESCRIPTIVE ANATOMY. 
The borders are four. 
The anterior, for articulation with the frontal bone, and the 
posterior, for the occipital, are serrated. 
The superior border, for articulation with its fellow, is 
straight, serrated and thick. 
The inferior border, for articulation with the squamous portion 
of the temporal bone, is short, curved and beveled at the ex- 
pense of the outer table. 
The angles are four. 
The anterior superior and the posterior superior are right 
angles. The anterior inferior is long, thin and marked on its 
inner aspect by a furrow formed by the middle meningeal artery. 
The posterior inferior is blunt and usually marked internally by 
the groove for the lateral sinus. 
Frontal. 
The frontal (os frontale) bone is situated at the front and 
base of the cranium. In the early life the bone consists of sym- 
metrical lateral halves, separated by a vertical suture, which, 
however, becomes ossified later in life, though the bone could 
still be described as consisting of two similar lateral portions, 
the bone is described as being made up, in each of its lateral 
halves, of two portions-the vertical, or frontal, and the hori- 
zontal, or orbito-nasal portion. 
The vertical portion (squama) forms the skeleton of the fore- 
head and presents two surfaces and a lateral aspect. Upon 
the anterior surface, which is convex both from above down- 
ward and from side to side, there are seen superiorly a smooth, 
rounded surface; below this on either side a bulge, called the 
frontal eminence (tuber frontale) ; below this a broad, shallow, 
transverse groove; below this a transverse ridge, the super- 
ciliary. The union of the two superciliary ridges on the middle 
line forms a prominence called the glabella, or nasal tuberosity. 
Below the superciliary ridge is seen the margin of the orbit, 
called the supra-orbital ridge, which terminates at the inner 
extremity in the internal angular process, and at its outer 
extremity in the external angular, or zygomatic, process. OSTEOLOGY. 
73 
The external angular process is sharp, thin and serrated for 
the orbital process of the malar. The internal angular pro- 
cess is rough, strong and bounds the nasal notch. About the 
inner third of the supra-orbital ridge is a notch, sometimes 
formed into a foramen, called the supra-orbital notch or foramen. 
The posterior face of the vertical portion is concave and 
marked by digital pits and arborescent furrows for the arteries. 
In the middle line this surface presents superiorly a groove for 
the longitudinal sinus, which, as it descends, terminates in a 
ridge, at the extremity of which is a small opening, called the 
foramen coecum. 
The lateral aspect of the bone presents a ridge curving upward 
and backward from the external angular process, and called 
the temporal ridge; behind this the surface is sunken and forms 
part of the temporal fossa. Both the temporal ridge and fossa 
are only partially seen on the frontal bone, for, in the articulated 
skull, they are continued on to the parietal and temporal bones. 
The horizontal portion consists of two lateral parts, the orbital 
plates, separated by a rectangular notch, the ethmoidal fissure. 
Each orbital plate presents an inferior and a superior surface. 
The inferior face is smooth, triangular, with the apex backward 
and the base running forward to the supra-orbital ridge, and 
concave, the concavity being greatest behind the external angular 
process-the lachrymal fossa. It has, just external to the in- 
ternal angular process, a depression called the fovea trochlearis. 
The upper surface of the orbital plate is convex and rough, pre- 
senting irregular rough eminences and corresponding depres- 
sions for the orbital surface of the brain. 
The ethmoidal fissure, the margins of which present several 
half cells, which, when articulated with the ethmoid, complete 
the ethmoidal cells, is the rectangular notch separating the two 
orbital plates. The cells are bounded on either side by a rough 
edge of bone, the inner for the lateral border of the cribriform 
plate of the ethmoid, and the outer for the upper border of the 
os planum of the ethmoid and the lachrymal. 
In front is a rough depression between the two lateral angular 
processes, called the nasal notch, descending from the middle of 
which is a long pointed process, the nasal spine. Upon the 74 
DESCRIPTIVE ANATOMY. 
posterior surface of the nasal spine is a vertical ridge. In the 
front portion of the ethmoidal notch, and external to the nasal 
spine, are the openings of the frontal sinuses. The frontal 
sinus, one on each side of the middle line, is an irregular cavity 
between rhe two tables of the vertical portion, which gradually 
increase in size from the time it makes its appearance in early 
life. 
The borders of the frontal bone are two-superior and in- 
ferior. The superior border is semi-circular and serrated for 
articulation with the parietal bones. When examined closely 
it is seen to be beveled superiorly at the expense of the inner 
table, and inferiorly at the expense of the outer. 
The inferior border is the posterior termination of the orbital 
plates, interrupted in the middle by the ethmoidal notch. It is 
straight and articular with the lesser wing of the sphenoid. 
At the angle of the junction of the two borders there is a rough 
triangular surface, the sphenoidal triangle, for articulation with 
the greater wing of the sphenoid. 
Temporal Bone. 
The temporal bone (os temporale) is divided for study into 
the squamous, mastoid and petrous portions. The tympanic 
portion is considered with the organ of hearing. 
The squamous portion occupies the upper front part of the 
bone and consists of two surfaces, a semi-circular border and 
a projection called the zygoma. 
The internal surface is concave from above downward and 
from before backward. It is marked by irregular, antero- 
posterior elevations with intervening depressions for the sulci 
and convolutions of the brain, and by grooves winding upward 
and backward for meningeal arteries. No distinct line, in the 
adult, marks the point of separation between the squamous and 
petrous portions. 
The external surface may be conveniently divided into two 
parts-that which lies above and that which lies below the 
zygoma. The part above is convex from above downward, 
slightly convex from before backward, rough for muscular at- OSTEOLOGY. 
75 
tachment and enters into the formation of the temporal fossa. 
Posteriorly it is separated from the mastoid portion by a rough 
line, part of the temporal ridge. The rest of this surface is 
occupied by the zygoma and the glenoid cavity. 
The zygoma, or zygomatic process, at its origin from the 
squamous portion, passes outward with a slight inclination for- 
ward, but after a course of about one-fourth of an inch, is 
twisted upon itself so that the surfaces and borders change 
their relative positions. At its origin the surfaces are superior 
and inferior, the first occupied by a groove, the second by a 
roughened tubercle; but in the remainder of its course, where 
it passes forward with but a slight inclination outward, the 
surfaces become internal and external, the borders superior and 
inferior. The external surface is rough, convex both from 
above downward and from before backward. The internal sur- 
face is concave in both directions and smooth. The superior 
border is longer, thinner and sharper than the inferior, which 
is thick and rough and short. Anteriorly it terminates in a 
rough serrated extremity, obliquely cut from above downward 
and backward, and intended for articulation with the malar. 
Posteriorly, the zygoma rises by two rough lines called the roots 
of the zygoma. The anterior root is continuous with the in- 
ferior border and terminates in a rough projection called the 
tubercle of the zygoma, from which a smooth elevated ridge, the 
eminentia articularis, passes inward as the anterior boundary 
of the glenoid cavity. The posterior root passes backward, 
just above the glenoid cavity and the external auditory meatus, 
and then, curving upward, forms the continuation of the tem- 
poral ridge which separates the squamous from the mastoid 
portion. Just after it passes above the glenoid cavity, it sends 
downward a prominent articular projection, sometimes called 
the middle root of the zygoma, which forms the posterior boun- 
dary of the articulation for the lower jaw. Between the pos- 
terior root and the auditory meatus is the supra meatal triangle 
of Macewen. 
The glenoid cavity (mandibular fossa) is concave and oval in 
outline, its long diameter being directed from without inward 
and backward; it is bounded in front by the eminentia articu- 76 
DESCRIPTIVE ANATOMY. 
laris, a smooth, rounded, oval articular ridge, which is a con- 
tinuation of the anterior root of the zygoma. Posteriorly it 
is limited by a rough, quadrilateral sheet of bone called the 
tympanic plate, while in the middle is a well defined slit, the 
Glaserian fissure, which divides the cavity into an anterior ar- 
ticular portion and a posterior non-articular. The articular 
portion is limited behind by the middle root of the zygoma, 
sometimes called the post-glenoid tubercle. 
The semi-circular border is rough, thin and sharp above, 
strongly beveled at the expense of the inner table; thick and 
serrated below and slightly beveled at the expense of the outer 
table. 
The mastoid portion consists of an internal and external sur- 
face, superior and posterior borders and a rough nipple-like 
projection, the mastoid process. 
The internal surface presents but one mark of note. It is 
smooth and has a deep groove which runs from above down- 
ward and forward. It is called the fossa sigmoidea (sigmoid 
sulcus). 
The external surface is rough throughout, and presents near 
the posterior border a large foramen, called the mastoid, which 
is sometimes found in the suture between this bone and the 
occipital and sometimes is altogether wanting. 
The mastoid process is a rough, blunt projection of bone, 
marked internally by a deep groove, the digastric fossa (mastoid 
notch), internal to which is a shallower groove for the occipital 
artery and known as the occipital groove. The inferior of the 
mastoid portion is hollowed out into a number of cellular 
cavities. 
The superior border is rough, serrated and nearly straight 
to receive the posterior inferior angle of the parietal. 
The posterior border, longer than the superior, slopes from 
above downward and forward and is roughened for articulation 
with the occipital. 
The petrous portion is a pyramidal projection of bone with 
its apex directed inward and forward and its base outward and 
backward. It presents three surfaces, anterior, posterior and 
inferior, and three borders, superior, anterior and posterior. OSTEOLOGY. 
77 
The posterior surface is the simplest of the three. Internal 
to its middle point it presents an oblique oval opening, the 
internal auditory, or acoustic, meatus. This opening leads into 
a short canal, directed outward and forward, at the bottom of 
which may be seen a bony lamina perforated by numerous 
apertures and crossed by a transverse ridge (crista falciformis). 
External to the internal auditory meatus and near the posterior 
border, is seen a little slit-like aperture which leads to the aque- 
ductus vestibuli. Between the two, and near the superior border, 
is usually seen a slighter depression which lodges a process 
of the dura mater. 
The anterior surface presents near the middle a round eleva- 
tion (eminentia arcuata) which marks the position of the 
superior semi-circular canal; external to this a smooth concave 
surface forms the roof of the tympanum (tegmen tympani) ; 
below and in front of the bulge is a groove leading outward and 
backward to an opening, the hiatus Fallopii, while at the junc- 
tion of the squamous and petrous portions may sometimes be 
seen another and slighter groove, the lesser petrosal. Near the 
apex of the bone is seen a depression (the trigeminal impres- 
sion) for the Gasserian ganglion, while at the apex the roof 
of the carotid canal is usually wanting and a part of the canal 
may be seen from the anterior surface. 
The inferior surface is rough and irregular and has upon it 
eleven points which require examination. Near the apex of the 
bone is a rough, nearly quadrilateral surface which gives at- 
tachment to muscular fibres. External to this is a circular 
opening, the aperture of entrance of the carotid canal. At first 
this canal passes upward in the bone, but it abruptly turns for- 
ward and inward and downward, pursuing a course parallel 
with that of the petrous bone, to emerge at the apex. External 
to and slightly behind this, is a smooth, concave surface, which 
encroaches on the posterior border of the bone, called the jugular 
fossa. On the bony partition separating the jugular fossa from 
the carotid aperture, is a small foramen (inferior tympanic 
canaliculus) which transmits Jacobson's nerve; and on the inner 
wall of the fossa itself is another foramen (mastoid canaliculus), 
smaller in size, for Arnold's nerve. Behind and slightly internal 78 
DESCRIPTIVE ANATOM X. 
to the carotid aperture, near the posterior border and directly 
beneath the internal auditory meatus, is a small opening, the 
aqueduct of the cochlea. In front of and external to the carotid 
aperture is a thin, prominent tongue of bone, which extends 
outward to become continuous with the auditory process, called 
the vaginal process. At its base this process splits into two 
sheets, one in front of the other, to enclose a sharp-pointed pro- 
jection, the styloid process. This, the longest of such processes 
in the body, passes downward and slightly forward and outward. 
Behind and external to this is a large foramen in the bone, the 
stylo-mastoid; while between the vaginal process and the mastoid 
process is a slight groove, the auricular fissure. At the junction 
of the posterior border of the mastoid portion with that of 
the petrous portion, there is a rough articular surface called the 
jugular facet. 
The borders are three, superior, posterior and anterior. 
The superior border, the longest of the three, presents along 
its upper margin a groove for the greater petrosal sinus, and 
near the apex of the bone a notch to lodge the fifth cranial nerve. 
The posterior border, intermediate in length, usually presents 
near its middle a rough tongue of bone which divides the jugular 
fossa into two portions. The remainder of the border is rough 
for articulation with the basilar process of the occipital. Along 
this border is a half groove, completed by articulation with 
the occipital, and lodging the lesser petrosal sinus. 
The anterior border is the shortest of the three, and is in part 
articular for the greater wing of the sphenoid. In the receding 
angle between the petrous and squamous portions there is seen 
an irregular opening, divided into an upper and a lower portion 
by a thin shelf of bone known as the processus cochleariformis. 
The canal above this shelf is for the tensor tympani muscle, 
while that below is intended for the Eustachian tube. 
The base of the petrous portion is partly interposed between 
the other two portions and partly continuous with them. On 
the free portion is seen the opening into the ear, the external 
auditory meatus, which is situated between the mastoid process 
behind and the middle root of the zygoma in front, and between 
the posterior root of the zygoma above and the auditory process OSTEOLOGY. 
79 
below. The auditory process is a rough curved sheet of bone 
continuous with the vaginal process, and partly circumscribing 
the external auditory meatus. 
The apex of the petrous portion is rough and presents a large 
irregular aperture, the aperture of exit for the carotid artery. 
It is received between the basilar process of the occipital bone 
and the posterior border of the greater wing of the sphenoid. 
The Sphenoid. 
The sphenoid (os sphenoidale) occupies a position near the 
middle of the base of the skull, and may be considered the key- 
stone of the cranial arch, since it serves to bind together all 
the bones of the skull and five of those of the face. It has been 
likened to a bat with the wings spread out, and is divided for 
study into a body, two wings, greater and lesser, on either side, 
and two projections, or processes, called the pterygoid. 
The body presents six surfaces, superior, inferior, anterior, 
posterior and two lateral. 
The upper surface commences in front in a triangular spine 
which, from its articulation, is known as the ethmoidal spine of 
the sphenoid. Behind this projection there may sometimes be 
seen a line or ridge leading backward and a slight transverse 
ridge, the optic, stretching between the anterior margins of the 
optic foramina. Behind this is a broad, transverse groove, the 
optic or chiasmatic, and behind this a prominent, rounded ele- 
vation, the olivary ridge (tuberculum sellse). Behind the olivary 
ridge is a deep pit-like depression, the sella turcica, or pituitary 
fossa (fossa hypophyseos), overhanging which behind is a 
square projection, the dorsum Ephippii, whose posterior sur- 
face, running obliquely downward and backward, is called the 
clivus. On either side of the mid-line in front of the optic ridge 
is a slight antero posterior groove, continuous with one on the 
upper surface of the ethmoid, in the articulated skull, for the 
olfactory bulb. Behind the optic ridge the optic groove extends 
across to terminate at either end in the corresponding optic 
foramen. The olivary ridge terminates at each extremity in a 
small projection, the middle clinoid process, which is sometimes 80 
DESCRIPTIVE ANATOMY. 
connected by a spicule of bone with the anterior clinoid process 
of the lesser wing. The sella turcica, deep and pit-like, is 
bounded in front by the olivary ridge, behind by the dorsum 
Ephippii, laterally by the margin of the carotid groove. The 
dorsum sellae terminates at either angle in a rough projection, 
the posterior clinoid process, sometimes connected to the an- 
terior, sometimes with the middle, clinoid process by a spicule 
of bone. The posterior surface of the dorsum, or the clivus, is 
a rough, quadrilateral, sloping surface, continuous in the ar- 
ticulated skull with the upper surface of the basilar process of 
the occipital. 
The posterior surface is rough and square, presenting many 
nipple-like projections for articulation with the basilar process 
of the occipital. In advanced life it is ossified to the occipital. 
The anterior face presents in the middle a prominent, rough 
vertical ridge called the crest of the sphenoid, for articulation 
with the posterior border of the perpendicular lamella of the 
ethmoid. On either side of the crest the surface is rough and 
presents near the middle the opening into the sphenoidal sinuses. 
The margins of the opening are rough for articulation with the 
os planum and posterior extremity of the lateral mass of the 
ethmoid, the latter through the pyramid of Wistar (sphenoidal 
conchae). 
The inferior surface is marked in the middle by the continua- 
tion of the crest, called the sphenoidal rostrum. The rostrum is 
broad behind, narrow and more prominent in front, and is re- 
ceived into a fissure on the upper border of the vomer. On 
either side of the rostrum is a smooth surface for articulation 
with the alae of the vomer, external to which is the vaginal pro- 
cess for the under surface of each ala, external to which is the 
groove called the pterygo-palatine, converted into a canal of the 
same name by articulation with the palate bone. 
The lateral surfaces are almost taken up by the origin of the 
greater wings. The space just above each wing is occupied 
by a broad winding groove, the cavernous, which terminates at 
the lesser wing. In front of this the lateral surfaces are smooth, 
slightly concave from above downward, and enter into the for- OSTEOLOGY. 
81 
mation of the sphenoidal fissure and the inner wall of the orbit. 
On the side of the body, just in front of the beginning of the 
cavernous groove, is a spicule of bone called the fingula. 
The lesser wings (alae parvae). Each lesser wing springs 
by its perforated base from the junction of the lateral and 
superior surfaces of the body, and passes outward to terminate 
in a pointed process near the junction of the greater wing and 
the frontal. They each present two surfaces, superior and 
inferior, and two borders, anterior and posterior. The upper 
surface smooth, slightly concave, broad internally and narrow 
without, forms a part of the anterior fossa of the skull. The 
inferior, narrower than the superior, is smooth and slightly 
convex in outline and forms a part of the roof of the orbit and 
the upper boundary of the sphenoidal fissure (superior orbital 
fissure). The anterior border is thin, straight and serrated 
for articulation with the straight border of the frontal. The 
posterior, thicker than the anterior, begins internally in a 
bluntly pointed projection called the anterior clinoid process, 
which passes backward and inward. This border is concave and 
smooth, thinner in the middle than at either extremity, and 
terminates externally in the outer end of the lesser wing. The 
perforation found at the base of the lesser wing is the con- 
tinuation of the optic groove of the upper face, is called the optic 
foramen and leads forward, downward and outward to the 
cavity of the orbit. 
The greater wings (alae magnae) spring from the lower part of 
the lateral aspect of the body and pass upward, outward and for- 
ward. Each is divided into four surfaces, superior, anterior, 
external and interior. The circumference of the greater wing 
will be described later. 
The upper surface of the greater wing is concave and enters 
into the formation of the middle fossa of the skull. It is, con- 
sequently, marked by elevations and depressions corresponding 
to the sulci and convolutions of the temporo-sphenoid lobe of 
the brain which it lodges. It is more deeply concave anteriorly 
where it is overhung by the lesser wing than at any other part. 
Near the junction of the wing with the side of the body, and 
immediately beneath the sphenoidal fissure, there is a circular 82 
DESCRIPTIVE ANATOMY. 
foramen called, from its shape, the foramen rotundum. Its 
direction is downward, forward and slightly outward, and its 
anterior opening is found just external to and above the base 
of the pterygoid process. Behind and external to the foramen 
rotundum is the foramen ovale, looking directly downward and 
opening on the inferior face of the greater wing. Behind and 
external to this is found the foramen spinosum, also opening 
directly forward. Internal to the foramen ovale the foramen 
Vesalii may usually be seen. 
The external face inters into the formation of the temporal 
fossa. It is broader above than below, slightly rough for muscu- 
lar attachment, concave both from above downward and from 
before backward, and perforated by a number of small foramina. 
The inferior face is a part of the zygomatic, or infra-temporal, 
fossa, is small and quadrilateral in shape, looks downward and 
outward, and is slightly roughened for the attachment of 
muscles. Upon it open the foramen ovale and the foramen 
spinosum. It is divided from the outer face by the infra-tem- 
poral, or pterygoid, ridge. 
The greater part.of the anterior face (orbital) looks into and 
forms a part of the orbital cavity. It is triangular in form, the 
apex directed backward and inward and the base outward, con- 
cave from above downward, flat from before backward and per- 
forated by one or two smah foramina. Just below this portion 
of the anterior face is a small flat surface of bone forming a 
part of the pterygo-maxillary fossa and upon which the fora- 
men rotundum opens. 
The borders. The circumference of the greater wing may be 
considered as forming the borders of its four surfaces. From 
the side of the body to the spine of the sphenoid is the posterior 
border of the upper surface; from the spine to the point for 
articulation with the parietal is the outer border of the upper 
surface; from this point to the body is the upper border of the 
superior surface. The outer face, which is quadrilateral in 
form, has four borders. Its superior border extends from the 
outer border of the upper face to the anterior face; its anterior 
border from this point to the pterygoid ridge; its inferior border 
is the pterygoid ridge, while its posterior border is that part OSTEOLOGY. 
83 
of the outer border of the upper face extending from the ptery- 
goid ridge to the summit of the bone. The anterior face is 
bounded above by the inner part of the upper border of the 
superior surface; anteriorly or externally by the anterior border 
of the outer face, and below by a ridge leading from the ptery- 
goid ridge to the base of the pterygoid process. The posterior 
border of the upper surface is rough in its outer half for the 
anterior border of the petrous portion of the temporal; the outer 
border is serrated for the squamous portion of the temporal; the 
outer part of its upper border is rough for the frontal. The 
upper border of the outer face is articular for the anterior in- 
ferior angle of the parietal; the anterior border is articular for 
the posterior border of the orbital process of the malar. The 
inner part of the upper border of the superior face, and the 
lower border of the anterior face are non-articular, the one 
entering into the formation of the sphenoidal fissure, the other 
into the spheno-maxillary. The frontal triangle is found at the 
junction of the upper, outer and anterior surfaces. It is bounded 
in front by the anterior face; externally by the outer face; be- 
hind by the superior surface. The inner part of the posterior 
border of the upper surface forms the anterior boundary of the 
middle lacerated foramen. 
The pterygoid process (processus pterygoidei). The ptery- 
goid process springs from the junction of the greater wing and 
the body. Each process consists of two plates, internal and 
external, united above and diverging below. Viewed from the 
front the united plates present a triangular smooth surface 
above, forming the posterior wall of the spheno-maxillary fossa, 
pierced above by a round opening, the anterior opening of the 
Vidian or pterygoid foramen. Below and internal to this is a 
narrow rough articular strip for the posterior border of the 
vertical plate of the palate, terminating below at the divergence 
of the two plates. Posteriorly the united plates are grooved 
above and bifurcated below. Just above the groove, more on 
the posterior border of the greater wing than on the pterygoid 
process, is the posterior opening of the Vidian canal. Below 
this the posterior border of the inner plate shows an oblong, 
shallow fossa, the scaphoid. Below and external to the scap- DESCRIPTIVE ANATOMY. 
84 
hoid fossa is the pterygoid fossa, formed by the junction of the 
two plates in the separated bone, but filled in below in the 
skull by the tuberosity of the palate. The pterygoid fossa is 
deepest and broadest at its upper portion. The gap between 
the plates below is called the pterygoid fissure. The inner plate 
is longer and narrower than the outer. Its internal surface is 
smooth, except the anterior part, which is rough for the palate, 
and forms the outer boundary of the posterior nares; its outer 
surface, smooth and concave, forms the inner boundary of the 
pterygoid fossa. The anterior border, blended with the outer 
plate above, presents a serrated margin for a groove on the 
palate. Its posterior border is thin and sharp and terminates 
below in a thin curved plate of bone, the hamular process, which 
projects below the level of the outer plate, and is curved out- 
ward and backward. The outer plate, broader and more mas- 
sive than the inner, presents an outer face which is concave 
and rough to form the inner wall of the zygomatic fossa, an 
internal face, rough and irregularly concave, which forms the 
outer wall of the pterygoid fossa; an anterior border serrated 
below for the groove on the palate, and a posterior border 
which is thin, sharp and irregular, sloping obliquely downward 
and backward. 
The Ethmoid. 
The ethmoid (os ethmoidale) lies in the middle of the ante- 
rior fossa of the skull. It consists of a body and two lateral 
masses. A portion of the body can be seen by looking into the 
anterior fossa of the skull, and part of the lateral masses by 
looking into the orbital cavity, but the larger portion of the 
bone is concealed by surrounding bones. 
The superior surface of the body is called the horizontal or 
cribriform plate (lamina cribroso), has on it an antero-posterior 
groove, the olfactory, and is perforated by numerous small fora- 
mina. These foramina are arranged in three rows, of which 
the internal and external are fairly distinct, while the middle 
row is irregular and indistinct. The anterior foramen of the 
internal row, situated at the base of the crista galli, is a narrow, OSTEOLOGY. 
85 
split-like aperture for the transmission of the nasal nerve. The 
cribriform plate is a depressed surface, concave from side to 
side, and marked on the mid-line by a projection, called the 
crista galli (L. a cock's comb). This projection commences near 
the posterior end of the bone, and rapidly rising in height, 
terminates near the anterior end of the bone in a blunt, rounded 
point. Its posterior border is narrow and sharp. Its lateral 
aspects, smooth and slightly concave at the lower portion, are 
marked above by a bulging projection, which varies greatly 
in size in different bones. Projecting from the front of the 
crista galli are two small processes, one towards either side, 
called the alar processes (L. ala, a wing). On the anterior 
border is a groove which, when articulated with the frontal, 
forms the foramen coecum. Posteriorly the superior surface 
presents a deep notch, the sphenoidal fissure, for the reception 
of the ethmoidal spine of the sphenoid bone. The lateral edges 
of the cribriform plate are thin and articular for the cerebral 
margin of the notch in the frontal. 
From the lower surface of the cribriform plate there passes 
downward, on the middle line, a thin sheet of bone called the 
perpendicular lamella (lamina perpendicularis), which aids in 
forming the septum of the nose. This bony plate is usually bent 
toward one side, is grooved on both surfaces, and presents ante- 
rior, posterior and inferior borders for articulation with the 
bones and cartilage which completes the nasal septum. 
The lateral mass (labyrinthus ethmoidalis) lies to the side of 
the perpendicular lamella, with a slight interval between. It 
presents an outer, inner and superior face. 
The outer surface forms part of the inner wall of the orbit; 
it is smooth, flat and quadrilateral and is called the os planum 
(lamina papyracea) ; its upper part is marked by two grooves, 
which become the anterior and posterior ethmoidal foramina. 
The internal surface is convex, rough and fissured behind; this 
fissure is called the superior meatus of the nose; above this is 
a curved portion of the bone called the superior turbinated bone 
(superior nasal concha) ; below the superior meatus is another 
portion called the middle turbinated bone (middle nasal concha), 
which is the upper limit of the middle meatus of the nose. The 86 
DESCRIPTIVE ANATOMY. 
superior surface of the lateral mass presents numerous irregu- 
lar openings into the cells, of which this part of the bone is 
made up; these are closed in by the overlapping horizontal plate. 
Projecting downward and backward from the lower edge of 
the lateral mass is a thin plate of bone called the uncinate pro- 
cess, which articulates with the ethmoidal process of the in- 
ferior turbinated and helps to close the opening of the maxillary 
antrum. From the posterior extremity of the lateral mass there 
projects backward a triangular, curled, pointed process, which 
extends into the sphenoidal cell of that side, and, as puberty ap- 
proaches, becomes detached from the ethmoid and ossified to the 
sphenoid; it is called the sphenoidal spongy bone, or pyramid of 
Wistar. The cells, of which the lateral mass consists, are sepa- 
rated by a transverse septum into the two sets, the anterior and 
posterior ethmoidal cells; the anterior communicate with the 
middle meatus by a tortuous canal called the infundibulum, with 
which the frontal sinus also communicates. The infundibulum 
opens into the upper front part of the middle meatus by a large 
orifice. At the upper back part of the superior meatus is an 
orifice which leads into the posterior ethmoidal cells. 
The Nasal Bones. 
The nasal bones (ossa nasalia) are two somewhat flat bones, 
forming the bridge of the nose, along the centre of which they 
articulate with each other. They are somewhat quadrilateral, 
and present for examination two surfaces, anterior and pos- 
terior, two borders, internal and external, and two extremities, 
superior and inferior. 
The anterior surface, which looks forward and slightly out- 
ward, is concave from above downward, and slightly convex 
from side to side, is a little roughened and marked by nutrient 
foramina. 
The posterior surface, which looks inward as well as back- 
ward, is convex from above downward, and marked near the 
internal border by a vertical groove. OSTEOLOGY. 
87 
The superior extremity is thicker and more massive than the 
inferior, and is roughened and serrated for articulation with 
the nasal notch of the frontal bone. 
The inferior extremity is broader and thinner than the su- 
perior, and slopes obliquely from within outward and down- 
ward, so that when the two bones are articulated, a pear-shaped 
notch is found between them, its apex upward and its base 
downward. Near the internal border is a notch for the nasal 
nerves. 
The internal border is shorter than the external, and presents, 
when articulated with its fellow, a well-defined crest for articu- 
lation with the nasal spine of the frontal and the perpendicular 
lamella of the ethmoid bone. 
The external border, longer than the internal, is serrated, thin, 
and sharp for articulation with the nasal process of the superior 
maxillary. 
Lachrymal Bone. 
The lachrymal BONE (os lacrimale) is a small bone on the 
inner wall of each orbit in front of the os planum. The bone re- 
motely resembles a finger nail and hence acquires its synonym 
of unguis. It presents two faces, two extremities and two 
borders. 
The external face is divided into an anterior and a posterior 
portion, by a vertical ridge, which terminates inferiorly in a 
hook-like process called hamular. The posterior and larger por- 
tion is part of the inner wall of the orbit and is flat and smooth. 
The anterior portion is a vertical groove, called the lachrymal. 
The internal face is rough for articulation with the ethmoid 
bone, and presents a vertical groove corresponding to the ver- 
tical ridge on the opposite side; the portion of the surface 
in front of this groove enters into the formation of the middle 
meatus. 
The upper extremity articulates with the internal angular 
process of the frontal bone. 88 
DESCRIPTIVE ANATOMY. 
The lower extremity is divided into two parts, the posterior 
articulating with the orbital plate of the superior maxillary, the 
anterior projecting farther downward and articulating with the 
lachrymal process of the inferior turbinated. 
The anterior border articulates with the nasal process of the 
superior maxillary bone. 
The posterior border articulates with the os planum. 
Inferior Turbinated Bone. 
The inferior turbinated (inferior nasal concha), or in- 
ferior spongy bone, is found in the lower part of the outer wall 
of the nasal fossa; the middle and superior turbinated bones are 
merely parts of the ethmoid. The bone is divisible into two ex- 
tremities, two faces and two borders. 
The anterior extremity is much the larger and articulates with 
the inferior turbinated crest of the superior maxillary. 
The posterior extremity is slender and pointed and articu- 
lates with the inferior turbinated crest of the palate bone. 
The internal face is convex and marked by apertures and 
grooves. 
The external face is concave and enters into the inferior mea- 
tus of the nose. 
The inferior border is rounded and free, marking the limit 
between the middle and inferior meatuses. 
The superior border articulates from before backward with 
the superior maxillary, the lachrymal, the ethmoid and the pal- 
ate bones. It presents three processes, lachrymal ethmoid and 
maxillary. The lachrymal process is directed upward to articu- 
late with the lower extremity of the lachrymal bone, and with 
the nasal process of the superior maxillary, aiding to form the 
lachrymal canal. The maxillary process is larger than the other 
two and is a curved plate of bone directed downward and out- 
ward from the base of the ethmoidal process and articulates 
with the superior maxillary by looking around the orifice of the 
antrum. The ethmoidal process is behind the lachrymal, and is OSTEOLOGY. 
89 
directed upward to articulate with the unciform process of the 
ethmoid. 
Vomer. 
The VOMER is a single bone found separating the nostrils be- 
hind and below, forming part of the septum of the nose; the 
upper part of the septum is the perpendicular lamella of the 
ethmoid; the anterior part is a plate of cartilage. It presents 
two faces and four borders. 
The faces are lateral and each forms part of the inner wall of 
a nostril, the bone usually bulging toward one side or the other. 
They are marked by shallow furrows and by the naso-palatine 
groove, which is directed obliquely downward and forward on 
each face. 
The superior border presents an antero-posterior groove 
which receives the rostrum of the sphenoid; the edges of the 
groove are projected outward into lips, or alse, each of which 
lies in the groove above the vaginal process of the sphenoid. 
The inferior border is received between the averted edges of 
the palate processes of the superior maxillary bones and of the 
horizontal plates of the palate bones. 
The anterior border presents a longitudinal fissure which re- 
ceives superiorly the perpendicular lamella of the ethmoid, in- 
feriorly the triangular cartilage of the septum; the lower part 
is occasionally not fissured, but rough. 
The posterior border is concave and free, terminating, pos- 
teriorly, the septum of the nose. 
Malar Bone. 
The malar BONE (os zygomaticum) forms the prominence of 
the check, is somewhat quadrangular, and presents for ex- 
amination four processes and a body which has two surfaces 
and four borders and four processes. 
The external or malar face is convex and has a foramen open- 
ing on it, called malar or zygomatico facial. 90 
DESCRIPTIVE ANATOMY. 
The posterior or internal face is smooth and concave, entering 
into the temporal fossa above and the zygomatic below. 
The frontosphenoidal projects upward to articulate with 
the external angular process of the frontal bone. The orbital 
process is a smooth projecting lip of bone curving downward 
from the frontal process, and projecting inward, forming a 
concavity which enters into the outer wall and floor of the orbit. 
Its lower surface forms part of the temporal fossa. Superiorly 
it articulates with the frontal bone. Posteriorly it articulates 
with the sphenoid bone; internal to which it articulates with the 
orbital plate of the superior maxillary bone; between these two 
articulations there is often seen the narrow, rounded, non-articu- 
lar anterior extremity of the spheno-maxillary fissure. This pro- 
cess presents the openings into one or more small canals, tem- 
poro-malar, which extend to the anterior surface of the bone 
and some usually to the posterior surface. 
The maxillary process is rough and triangular, articulating 
with the superior maxilla. 
The temporal process extends backwards, is long and narrow, 
and articulates with the zygomatic process of the temporal. 
The superior or orbital border is concave, smooth, and rounded, 
and forms part of the margin of the orbit. 
The inferior border is straight and continuous with the lower 
edge of the zygoma. 
The antero-inferior border is straight and rough to articulate 
with the superior maxilla. 
The posterior or temporal border is sinuous and continuous 
with the temporal ridge above, and below with the upper edge 
of the zygoma. 
Superior Maxillary. 
The superior maxillary bones form the upper jaw, and are, 
with the exception of the inferior maxillary, the largest bones of 
the face. Each bone articulates with the frontal and ethmoid, and 
all the bones of the face except the inferior maxillary. The bone 
is divisible into a body and four processes. OSTEOLOGY. 
91 
The body is irregularly quadrilateral, is hollowed out into a 
cavity called the antrum of Highmore, or antrum maxillare, 
and presents four faces-anterior, superior, posterior, internal. 
The anterior or facial surface is somewhat concave, and pre- 
sents about its centre a depression, called the canine fossa, which 
is limited internally by a vertical ridge, the canine ridge; on the 
inner side of the canine ridge is another depression, the incisive 
fossa; just above the canine fossa is a foramen, the infra- 
orbital. This surface is limited internally by the thin concave 
edge of the nasal fossa; below by the alveolar process; externally 
by the malar process and a ridge descending from it; superiorly 
by the margin of the orbit. 
The posterior or zygomatic (infra-temporal) surface, facing 
outward and backward, is partly occupied at its lower portion 
by a rough bulge, the tuberosity of the superior maxillary bone. 
It presents numerous small foramina. The upper limit of this 
surface, separating it from the orbital face, is a smooth, 
rounded border, on which is a notch, the commencement of the 
infra-orbital canal. The malar process separates this face from 
the anterior; below it is limited by the alveolar process; inter- 
nally by the posterior border, which separates it from the inner 
face. 
The superior or orbital surface forms the floor of the orbit. 
It is formed of a thin triangular plate of bone, is smooth, slop- 
ing downward and forward, and marked from behind forward 
by a groove, the infra-orbital canal, which disappears in the 
bone to terminate at the infra-orbital foramen on the anterior 
face. This face is bounded internally by a rough edge for articu- 
lation from behind forward, with the palate, ethmoid and 
lachrymal bones; anteriorly it is limited by the lower margin of 
the orbit internally, and externally by a rough border for articu- 
lation with the malar bone; externally it is separated from the 
posterior surface by a rounded border on which begins the 
infra-orbital canal by a notch; this border forming, in the 
articulated skull, the lower margin of a fissure, the spheno- 
maxillary. 
The internal or nasal surface aids in forming the outer wall 
of the nose, and presents a large, irregular aperture leading 92 
DESCRIPTIVE ANATOMY. 
into the antrum of Highmore; this aperture is much reduced by 
articulations with neighboring bones, palate, ethmoid, lachrymal, 
and inferior turbinated. The antrum is distinctly triangular; 
in it are seen numerous vertical grooves, and on its floor several 
conical projections, which mark the position of molar teeth. In 
front of the opening into the antrum is a deep vertical groove, 
the sulcus lachrymalis. This face is limited above by the nasal 
process in front, and behind this by a rough cellular edge for 
articulation with the lachrymal and ethmoid bones; inferiorly is 
the horizontal palate process, which may be said to divide it into 
two portions, the part below terminating in the alveolar process 
and the part above forming the inferior meatus of the nose. The 
posterior border is rough for articulation with the palate bone, 
and presents a spiral groove, which, when articulated with the 
palate bone, forms the posterior palatine canal. The anterior 
edge is sharp and concave, and forms the margin of the anterior 
nares. In front of the lachrymal groove is an antero-posterior 
ridge, the inferior turbinated (conchal) crest, for the anterior 
extremity of the inferior turbinated bone. 
The four processes are nasal, malar, palate, and alveolar. The 
nasal process (frontal process) is a long, thin, triangular pro- 
jection forming a part of the wall of the nose and presenting 
three borders and two surfaces. 
The anterior border is convex, thin, and serrated for articula- 
tion with the nasal bone. 
The posterior border, thick and grooved, is marked by two 
ridges, internal and external, surmounting the groove. The 
inner ridge is rough for articulation with the lachrymal; the 
outer, rounded, concave, and smooth, is continued into the mar- 
gin of the orbit, and presents below a small tubercle, where it 
receives the hamular process of the lachrymal. This groove, in 
the articulated skull, is formed into a canal for lodging the 
nasal duct, and is nearly vertical, being slightly oblique back- 
ward and outward. The upper border is blunt and serrated for 
articulation with the internal angular process of the frontal bone. 
The external face is slightly concave above, convex below, and 
marked by small foramina. OSTEOLOGY. 
93 
The internal face is crossed from behind forward by a rough 
ridge, the superior turbinated crest (ethmoidal crest) for the 
anterior extremity of the middle turbinated bone. Above the 
superior turbinated crest the surface is rough for articulation 
with the ethmoid. Below the superior turbinated crest the inner 
face is smooth and concave from above downward, entering into 
the outer wall of the middle meatus. 
The zygomatic process forms the upper part of the boundary 
between the anterior and posterior faces. It is concave both in 
front and behind, triangular in outline, and its summit is rough 
for articulation with the malar bone. 
The palate process projects inward from the lower part of the 
internal surface, forming a portion of the floor of the nose and 
the roof of the mouth. It does not extend as far back as the 
body of the bone, but may be said to be deficient behind. Its 
upper surface is transversely concave and smooth. In front 
is a foramen which leads into the anterior palatine canal, which 
appears on the inner border of the process as a groove. Its 
lower surface is also concave, but rough, marked by numerous 
shallow depressions and by a groove externally, which runs from 
behind forward to the anterior palatine groove. The inner 
border is rough to articulate with its fellow on the opposite 
side; it is thicker anteriorly than posteriorly, and its upper edge 
is raised into a ridge, or crest, which is slightly averted, so as 
to produce, when the bone is articulated, a narrow groove, for 
the reception of the vomer. Towards the front, the inner border, 
in its lower part, presents a groove, which sinks into the bone 
above to become, on the upper surface, the anterior palatine 
foramen. In front the inner border terminates in a slender, 
pointed process, which, united with a similar one on the opposite 
bone, forms the anterior nasal spine. 
The anterior border of the process is the thin concave margin 
of the nose, the nasal notch. 
The posterior border is straight and serrated for articulation 
with the horizontal plate of the palate bone. 
The alveolar process projects downward from the lower, 
outer part of the bone, and forms about a fourth of the circum- 94 
DESCRIPTIVE ANATOMY. 
ference of a circle. It is marked by sockets for eight teeth, with 
intervening septa. 
Palate Bone. 
The palate BONE (os palatinum) enters into the formation 
of the orbits, the nasal fossae and the roof of the mouth. It is 
divided into horizontal and vertical or perpendicular portions, 
or plates. 
The horizontal portion (pars horizontalis) projects inward, 
at about a right angle, from the lower limit of the vertical plate, 
and presents two surfaces and three borders. The superior or 
nasal face is smooth and concave transversely, forming the back 
part of the floor of the nose. The inferior face is also slightly 
concave transversely and rough, forming the posterior part of 
the hard palate. A transverse ridge crosses it posteriorly. The 
anterior border is serrated for articulation with the palate pro- 
cess of the superior maxillary. The posterior border is smooth, 
concave, and free, having its inner extremity prolonged back- 
wards by a slender, sharp process, which, with a similar pro- 
jection on the opposite bone, forms the posterior nasal, or palate 
spine. The internal border is thick, rough, and serrated for 
articulation with its fellow; the upper edge of this border is 
raised and produces, when articulated, a slight groove for the 
reception of the vomer. 
The vertical plate (pars perpendicularis) is irregularly quad- 
rangular, and presents two faces, internal and external, and 
three borders-superior, anterior, and posterior. The internal 
surface presents two transverse ridges, the superior, called the 
ethmoidal crest and the inferior, the conchal crest; the inferior 
to articulate with the inferior turbinated bone, and the superior 
with the middle turbinated bone of the ethmoid. This surface, 
below the inferior turbinated crest, is concave, and forms the 
outer boundary of the inferior meatus of the nose; the surface 
between the two crests is also concave, and forms a part of the 
middle meatus; above the superior crest is a narrow groove. 
The external surface is, to a great extent, rough for articula- 
tion with the internal face of the superior maxilla; but at its 
upper back part there is a smooth portion, which forms a part OSTEOLOGY. 
95 
of the spheno-maxillary fossa. At the posterior part of this 
face is a vertical groove, converted into the posterior palatine 
canal by articulation with the posterior border of the superior 
maxilla. 
The superior border presents two processes, separated by a 
deep notch. The notch is called spheno-palatine, and is con- 
verted into a foramen of that name by the articulation of the 
sphenoid bone. The anterior process is known as the orbital; 
the posterior as the sphenoidal. The orbital process inclines 
outward as it ascends, is hollow and higher than the sphenoidal, 
being perched upon a thin plate of bone, its neck. It presents 
five faces-anterior, posterior, internal, external, and superior- 
the first three being articular, the others non-articular. 
The anterior or maxillary face looks downward, forward, 
and inward, and articulates with the orbital surface of the su- 
perior maxillary. 
The posterior or sphenoidal face articulates with the front of 
the body of the sphenoid bone. 
The internal or ethmoidal face articulates with the ethmoid 
bone, and usually presents the opening into the cellular cavity 
in the process; but this is sometimes on the posterior face. 
The external or sphene-maxillary face looks downward and 
outward and forms a part of the inner wall of the spheno-max- 
illary fossa. 
The superior or orbital face looks forward and outward as 
well as upward, and forms the back part of the floor of the orbit. 
Of these five faces only the two latter are non-articular. 
The sphenoidal process is a thin plate of bone, inclining in- 
ward as it ascends, and presents three faces-superior, exter- 
nal, and internal-and two borders-anterior and posterior. 
The superior face articulates with the sphenoid bone and pre- 
sents a groove, converted, by articulation, into the pterygo- 
palatine canal. 
The external face partly enters into the formation of the 
spheno-maxillary fossa, and partly articulates with the pterygoid 
process of the sphenoid. 96 
DESCRIPTIVE ANATOMY. 
The internal face is free, and forms part of the outer wall of 
the nasal fossa. 
The anterior border of the process is the posterior boundary 
of the spheno-palatine notch. 
The posterior border of the process articulates with the ptery- 
goid process of the sphenoid bone. 
The anterior border of the perpendicular plate is irregular, 
articulates with the superior maxillary bone, and presents, at 
the intersection of the inferior turbinated crest, a thin process, 
the maxillary, which aids in closing the opening into the antrum 
maxillare. 
The posterior border of the perpendicular plate is grooved, 
and articulates with the pterygoid process of the sphenoid. At 
its lower part is a process, the pterygoid tuberosity or pyramidal 
process of the palate bone. It is triangular, is directed down- 
ward, backward, and outward, and fits into the interval between 
the two plates of the pterygoid process of the sphenoid. De- 
scending the middle of the tuberosity, posteriorly, is a smooth 
groove, which, when the bone is articulated, forms part of the 
pterygoid fossa; on each side of this groove is a rough groove, 
which articulates with the corresponding plate of the pterygoid 
process of the sphenoid. Externally the tuberosity is rough and 
articulates with the superior maxilla. The openings of numer- 
ous canals, the accessory posterior palatine canals, are seen on 
the tuberosity, and it is perforated vertically through its base 
by the posterior palatine canal. 
The Inferior Maxilla. 
The inferior maxilla (mandibula), or lower jaw bone, is a 
symmetrical bone, derived from lateral halves, which blend in 
the middle line-each lateral half consisting of a vertical por- 
tion, the ramus, and a horizontal portion, which is one-half of 
the body of the bone. 
The body is of a horse-shoe shape; and presents external and 
internal surfaces, superior and inferior borders. The surfaces 
do not look directly outward and inward; but the external in- OSTEOLOGY. 
97 
clines outward and forward, and the internal inward and back- 
ward. 
The external surface is convex from side to side, concave in 
some portions, from above downward. In front, on the mid- 
line of the body, is a vertical ridge, the symphysis menti (L. 
mentum, the chin), which, as it descends, spreads out so as to 
form a triangular projection, the mental process, mental pro- 
tuberance, which forms the prominence of the chin. External 
to this symphysis is a depression, called the incisive fossa; and 
just beyond this is a large and well-marked foramen, the mental 
foramen. Extending backward and upward from the mental 
foramen is a prominent ridge of the bone, which becomes con- 
tinuous with the anterior border of the ramus, called the ex- 
ternal oblique ridge. 
The internal surface is concave from before backward, ir- 
regular in outline from above downward. On the mid-line of the 
internal surface is a vertical groove corresponding to the sym- 
physis in front. On either side of this groove are seen two tu- 
bercles, one inferior and one superior, both a little below the 
middle point of the groove, which are known as the genial tu- 
bercles, superior and inferior, sometimes called the spinse men- 
tales. They are very irregular in formation; sometimes all four 
of them coalesce into a single roughened process; sometimes 
there are two flat ones on either side of the mid-line; and oc- 
casionally the four are distinctly seen. External to the genial 
tubercles is a slight depression, which in the fresh state lodges 
the sub-lingual gland. External to and below the tubercles is 
a slighter depression, called the digastric fossa, serving for the 
attachment of the muscle of that name. Extending upward and 
backward from the digastric fossa, and lying nearly opposite 
to the external oblique ridge, is a prominent ridge of bone, called 
the internal oblique ridge, or mylo-hyoidean ridge. Below this 
ridge and parallel to it is a long groove, which is called the sub- 
maxillary fossa. 
The upper border of the bone is called the aleolar process (L. 
Dim. of alveus, a cavity), and presents the depressions for six- DESCRIPTIVE ANATOMY. 
98 
teen teeth, these sockets being separated from one another by- 
intervening bony septa. 
The lower, or basilar, border is slightly everted, strong, 
rounded and smooth. It is the most prominent portion of the 
bone in the living man. Usually about an inch in front of the 
angle of the jaw this border presents a slight groove, in which 
passes the facial artery. 
The ramus is a quadrilateral projection of bone, which ex- 
tends nearly vertically upward, almost at right angles with the 
body of the bone. Its obliquity varies with the different periods 
of life. The ramus is divided for study into two surfaces, ex- 
ternal and internal, and four borders, anterior, posterior, su- 
perior, and inferior. 
The external surface is flat, is slightly roughened for muscular 
attachment, and presents no other mark of interest. 
The internal face, slightly concave from before backward, is 
marked about its centre by a very prominent projecting lip of 
bone (lingulas mandibulae), below and behind which is seen a 
large opening, the mandibulae foramen. Above this opening 
there is a groove leading downward and forward to the foramen, 
which leads into a canal, the dental, which extends through the 
bone. The canal terminates at the mental foramen on the exter- 
nal surface of the body. It is so located as to pass in close con- 
tact with the roots of the teeth, and lodges the blood-vessels and 
nerves which supply the fangs of each one of the teeth of the 
lower jaw. Leading downward and forward, into the sub-max- 
illary fossa, from the foramen, is a well-defined groove called 
the mylo-hyoid. 
The anterior border is thicker than the posterior, and is 
marked by a nearly vertical groove, which is surmounted by two 
lips. Of these the external lip, more prominent and sharper than 
the internal, is the upward continuation of the external oblique 
ridge; while the inner lip is an abutment that rises from the 
termination of the alveolar process, and becomes continuous with 
the mylo-hyoid ridge on the inner face of the body. OSTEOLOGY. 
99 
The posterior border is more rounded and thinner than the 
anterior, extending above into one of the projections of the 
upper border, and below terminating at the angle of the jaw. 
The lower border of the ramus should not be described as a 
separate border, as it is merely a continuation of the basilar 
border of the body. Where it joins with the posterior border 
of the ramus the bone is twisted so as to be everted, and forms 
a prominent projection, which varies greatly with the individual 
on either side of the face. This angle of the jaw is roughened 
for muscular attachment. 
The superior border consists of two projections, an anterior 
and posterior, with an intervening notch, the sigmoid. Of these 
projections the anterior is called the coronoid process, while the 
posterior is described as the condyle of the jaw, the notch be- 
tween the two being called the mandibular. The coronoid pro- 
cess is thin, triangular in outline; presents an anterior border, 
which is continuous with the outer lip of the groove on the an- 
terior border of the ramus, a posterior thinner and sharper bor- 
der, continuous with the sigmoid notch, and a blunt point, the 
extremity, which is received into the fibres of the temporal 
muscle. The mandibular notch is concave from before backward, 
its edge thin and sharp. Behind this comes the condyle, which 
consists of a convex, oval articular surface, mounted upon a 
constricted portion of the bone, called the "neck." The condyle 
is oblique in its direction, its long diameter being from without 
inward and backward. It is articular further down behind than 
in front, and fits into the glenoid cavity, which is found on the 
inferior surface of the squamous portion of the temporal bone. 
The neck of the condyle, constricted antero-posteriorly, extends 
laterally, so that the condyle seems to rest on two abutments, 
one from either side. In front and to the inner side is found a 
deep depression beneath each condyle. 
As life advances the obliquity with which the ramus of the 
bone ascends increases, so that in extreme old age it nearly pro- 
longs the direction of the body. This, however, is not due to a 
change in the direction of the bone, but to the loss of the teeth, 
and the consequent absorption of the alveolar process. 100 
DESCRIPTIVE ANATOMY. 
The Articulated Skull. 
The ARTICULATED skull is produced by the union of the bones 
of the cranium and the bones of the face. A description of the 
articulations, known as sutures, will be found under the head 
of articulations in general. 
The skull is divisible into five regions (normae) : superior, in- 
ferior, anterior and two lateral. 
Superior Region. 
The superior REGION or vertex (norma verticalis), is bounded 
in front by the superciliary ridges, on each side by the temporal 
ridge, and behind by the posterior protuberance and the su- 
perior curved lines of the occipital bone. It is formed by part 
of the frontal bone, most of the parietal bones and a part of the 
occipital bone. It is divided into a superior and an inferior 
aspect. 
The superior surface is seen to be crossed transversely by the 
coronal suture, extending backward from the centre of which 
is the sagittal suture, which terminates posteriorly in the lamb- 
doid suture. The junction of the coronal and sagittal sutures is 
called the bregma; that of the sagittal and lambdoid the lambda. 
The parietal foramen may be seen on each side of the sagittal 
suture near its posterior extremity. On each side is seen the 
parietal eminence. This surface is markedly convex. 
The inferior, or cerebral, surface is concave, and presents the 
following appearances: on the frontal bone, in the middle line, 
is seen the indistinct commencement of a groove, for the su- 
perior longitudinal or sagittal sinus, which passes backward, 
growing broader and more distinct as it travels, first along the 
line of union of the parietal bones and then down the superior 
limb of the occipital cross to terminate at the anterior occipital 
protuberance; along the edges of this groove are seen several 
pits for lodging the Pacchionian bodies, and external to these 
digital pits for the convolutions of the brain; numerous arbores- 
cent arterial furrows are also seen. OSTEOLOGY. 
101 
Lateral Region (Norma Lateralis). 
The lateral REGION is subdivided into three portions-mas- 
toid, temporal, zygomatic or infra-temporal, including the 
spheno-maxillary or pterygo-palatine fossa. 
Mastoid Portion. 
The mastoid portion of the lateral region extends backward 
from the eminentia articularis, and in it are seen the following 
appearances: the mastoid foramen and process; the external 
auditory meatus; the auditory process; the mandibular fossa, 
which is bounded above by the posterior root of the zygoma, be- 
hind by the middle root and vaginal process, and in front by the 
anterior root of the zygoma. It is crossed transversely by the 
petrotympanic fissure, the surface in front of the fissure being 
articular and that behind rough; where the roots of the zygoma 
meet is the tubercle. Between the superior root of the zygoma 
and the external acoustic meatus is the supra-meatal triangle. 
Temporal Portion. 
The temporal portion of the lateral region is also called the 
temporal fossa. Its upper anterior and posterior limit is the 
temporal ridge; this ridge commences at the external angular 
process of the frontal bone and curving upward and backward, 
leaves the frontal and passing across the parietal bone, arches 
downward over the squamous portion of the temporal bone and 
terminates in the posterior root of the zygoma. In front of the 
temporal fossa is the external angular (zygomatic) process of 
the frontal bone and the malar bone. Below, it terminates at 
the zygoma without and the pterygoid ridge within. Its con- 
stituents are furnished by the frontal, the malar, the greater 
wing of the sphenoid, the parietal, and the squamous portion of 
the temporal bone. DESCRIPTIVE ANATOMY. 
102 
Zygomatic Portion. 
The zygomatic portion (infra-temporal fossa) of the lateral 
region is situated below the temporal portion and is bounded 
above by the lower surface of the greater wing of the sphenoid, 
the pterygoid ridge and a line drawn from the pterygoid ridge 
to the zygomatic arch; in front by the posterior surface of the 
superior maxilla and by the malar; internally by the external 
pterygoid plate and pterygo-maxillary fissure, externally by the 
zygoma and the ramus of the inferior maxilla. In this region 
are seen two fissures, one horizontal, the sphero-maxillary, and 
one vertical, the pterygo-maxillary, the one being at right angle 
to the other. 
The spheno-maxillary (inferior orbital) fissure is seen by look- 
ing into the orbit. It is a triangular fissure, base outward, situ- 
ated at the lower part of the outer wall of the orbit, between the 
greater wing of the sphenoid above and the orbital plate of the 
superior maxilla below, terminating, frequently, in the mala** 
bone anteriorly. The posterior termination is at the point where 
the pterygo-maxillary fissure begins, which descends between the 
tuberosity of the superior maxillary in front and the pterygoid 
process behind. The pterygo-maxillary fissure is triangular in 
form, with its base directed upward and terminating, at a right 
angle, in the spheno-maxillary fissure. It establishes communi- 
cation between the pterygo-palatine and zygomatic fossae, and 
is bounded in front by the superior maxilla and behind by 
the outer edge of the anterior border of the external pterygoid 
plate. 
Spheno-Maxillary Fossa. 
At the point of junction of the two fissures is a small fossa, 
the size of the end of the little finger, called the spheno-maxillary 
or pterygo-palatine fossa; it is thus formed: postero-superiorly 
is the smooth flat surface at the front of the base of the pterygoid 
process; behind, the anterior border of the united pterygoid; 
in front, the inner part of the posterior surface of the superior 
maxilla; internally, the non-articular portion of the outer sur- 
face of the vertical plate of the palate; externally is the pterygo- OSTEOLOGY. 
103 
maxillary fissure, the door of communication with the zygomatic 
fossa. The following five foramina open into this fossa: the 
foramen rotundum, the pterygoid or Vidian (pterygoid canal), 
and the pterygoid-palatine (pharyngeal canal), on the postero- 
superior wall; the spheno-palatine on the inner, and the pos- 
terior palatine in the floor. The foramen rotundum leads from 
the middle fossa of the skull, the Vidian from the middle lacer- 
ated foremen, the pterygo-palatine from the base of the skull, 
the spheno-palatine from the back of the superior meatus of 
the nose and the posterior palatine from the roof of the mouth. 
Taking the lateral region of the skull as a whole, it may be 
seen, from the foregoing description, that it is triangular in 
outline and is bounded as follows: the base is represented by the 
sweep of the temporal ridge; the apex is at the angle of the 
inferior maxilla; the sides may be represented by two lines, 
meeting at the angle of the inferior maxilla, the one drawn from 
the external angle of the frontal bone and the other from the 
mastoid process. The bones entering into its formation are: 
the mastoid and squamous, and the base of the petrous portions 
of the temporal bone; a part of the frontal bone; part of the 
greater wing of the sphenoid, part of the parietal, part of the 
malar, and the constituents of the spheno-mixillary fossa, as 
given above. 
The Inferior Region of the Skull. 
The inferior region (norma basalis), or base of the skull, 
presents two surfaces, superior and inferior, or cerebral and 
basilar. 
The inferior surface is bounded in front by the alveolar pro- 
cess of the superior maxillary. From the tuberosity of the 
superior maxilla the line extends along the posterior border of 
the external pterygoid process, thence external to the spine of 
the sphenoid, skirts the inner boundary of the glenoid cavity, 
along the lower border of the vaginal process, to the mastoid 
process, which it ascends to meet the superior curved line of 
the occipital, which it follows to the posterior occipital pro- 
tuberance. 104 
DESCRIPTIVE ANATOMY. 
In describing the appearances found on this face of the skull 
it is much more accurate to begin with those on the mid-line 
of the body, which are single appearances, while the double 
appearances can be given later. Commencing on the mid-line 
we find extending from before backward a foramen called the 
anterior palatine. This foramen, appearing to be single, when 
viewed from below, terminates by dividing into four openings 
above. Of these the two lateral, one for each nasal cavity, are 
called foramina of Stenson, while the remaining pair, opening 
in the inter-maxillary suture, are known as foramina of Scarpa. 
Behind this foramen is the suture between the horizontal plates 
of the superior maxillary bones, and behind this again the suture 
between the horizontal plates of the palate bones. This suture 
terminates in the posterior palatine spine, while above and 
behind this spine is the concave free border of the vomer. 
Behind this comes the pharyngeal ridge of the basilar process 
of the occipital, which leads to the foramen magnum, beyond 
which is found the vertical limb of the occipital cross, which 
terminates in the posterior occipital protuberance. On either 
side the following appearances will be noted: in front, the 
rough inferior surface of the palatine process of the superior 
maxilla, behind which lies the suture between this process and 
the horizontal plate of the palate bones; near the alveolar 
border is seen the groove leading back to the posterior or great 
palatine foramen; behind this is the nasal cavity (choanae), 
on whose upper wall is seen the pterygo-palatine canal, and, 
on the outer side of the nasal cavity, the pterygoid process and 
pterygoid fossa of the sphenoid. Behind the pterygoid pro- 
cess is the middle lacerated foramen; external to that is the fora- 
men ovale; external to and behind this, the foramen spinosum; 
external to that the spine of the sphenoid; and then the appear- 
ances seen on the inferior surface of the petrous portion of 
the temporal bone. The most internal appearance is a rough, 
quadrilateral surface. Behind and external to this is the aper- 
ture of entrance for the carotid artery; external to and behind 
this a thin elongated projection of bone, called here the vaginal 
process. Internal to this is the foramen lacerum posterius, in 
which the aqueduct of the cochlea is almost concealed; and in OSTEOLOGY. 
105 
the interval between the posterior lacerated foramen and the 
carotid aperture of entrance is a thin sheet of bone marked by 
a minute aperture for the transmission of Jacobson nerve (in- 
ferior tympanic canaliculus) ; on the wall of the jugular fossa 
is a small foramen for the transmission of Arnold's nerve 
(mastoid canaliculus). The vaginal process, as it passes upward 
and backward, divides to enclose the next appearance, which 
is the styloid process, while next to the styloid process is a fora- 
men, the stylo-mastoid foramen. Still further behind is a nar- 
row fissure between the vaginal and mastoid processes called 
the auricular fissure (tympano-mastoid), while internal to the 
mastoid process is another and larger depression, known as the 
digastric fossa, and internal to that a depression called the 
occipital groove. 
We next encounter the appearances on the occipital bones, 
viz., the condyles, with condyloid fossae behind, and in the bot- 
tom of the fossae the openings of the posterior condyloid fora- 
mina, when these foramina are present. In front on either 
side of the condyle is seen the anterior condyloid foramen. 
Behind these appearances is the roughened posterior surface 
of the occipital bone as far up as its superior curved line. 
In describing the appearances on the base of the skull, it is 
necessary to give not only those appearances, but their boun- 
daries as well. Thus the two posterior nares (choanae) are 
bounded, each internally by the posterior border of the vomer, 
externally by the inner surface of the internal plate of the 
pterygoid process, above by the expanded ala of the vomer, 
and external to this the vaginal process of the sphenoid. Below 
they are bounded by the posterior concave free border of the 
horizontal plate of the palate. The middle lacerated foramen 
is bounded internally by the side of the body of the sphenoid, 
externally by the apex of the petrous portion of the temporal; 
in front it is bounded by the posterior border of the upper sur- 
face of the greater wing of the sphenoid. In this foramen 
may be seen the opening of the Vidian canal, leading to the 
termination of that canal in the spheno-maxillary fossa. To 
the outer side of the middle lacerated foramen can be distinctly 
seen the space between the squamous and petrous portions of 106 
DESCRIPTIVE ANATOMY. 
the temporal, in which are lodged the two canals, the upper 
for the tensor tympani, the lower for the Eustachian tube, sepa- 
rated from each other by a thin process of bone called the 
processus cochleariformis (L. cochleare, a spoon; forma, shape). 
The posterior lacerated foramen is bounded in front by the pos- 
terior border of the petrous portion of the temporal, and be- 
hind by the junction of the basilar process with the inferior 
border of the occipital, these two bones presenting notches, 
which when articulated together form the posterior lacerated, 
or jugular, foramen. 
The Superior Surface of the Base of the Skull. 
The SUPERIOR SURFACE of the BASE of the SKULL presents in 
front the foramen caecum, behind this the crista galli, behind 
the crista galli the articulation between the ethmoidal spine 
of the sphenoid and the sphenoidal notch of the ethmoid, behind 
that a transverse ridge slightly formed bounding the optic 
groove in front. Next is the groove itself; and behind that is 
its posterior boundary, the olivary process. Behind the olivary 
process is a deep depression on the upper surface of the sphe- 
noid, the sella Turcica (L. A Turkish saddle), behind the sella 
Turcica the dorsum ephippii (L. The back of a horse-cloth), 
behind that the clivus Blumenbachii (L. Clivus, a slope), lead- 
ing to the grooved upper surface of the basilar process of the 
occipital bone. Behind the clivus Blumenbachii is the foramen 
magnum, behind this the vertical limb of the occipital cross, 
and at the termination of the upper surface of the base of the 
skull the anterior occipital protuberance. 
To describe the lateral appearances more intelligently it is 
necessary to divide this portion of the skull, which is so irregu- 
lar in outline, into three fossee. These are known as the an- 
terior, middle, and posterior; and they descend like steps, the 
anterior being the highest, the middle next, and the posterior 
the lowest. 
The anterior fossa of the skull is bounded in front by the 
junction of the horizontal and vertical portions of the frontal 
bone; behind, in the mid-line, by the optic ridge, on either side OSTEOLOGY. 
107 
of which we have the posterior border of the lesser wings of 
the sphenoid. Laterally this surface is limited by the vertical 
portion of the frontal bone. 
The middle fossa has for its anterior boundaries the posterior 
boundaries of the anterior fossa, viz., the optic ridge in the 
centre and the posterior border of the lesser wings of the sphe- 
noid laterally. Posteriorly it is bounded in the mid-line by the 
basilar suture, laterally by the upper border of the petrous por- 
tion of the temporal. 
The posterior fossa is bounded in front by the basilar suture, 
on either side by the upper border of the petrous portion of 
the temporal, behind in the mid-line by the anterior occipital 
protuberance, and on either side of that by the lateral limbs 
of the occipital cross. The bones entering into the formation 
of the anterior fossa are the orbital plates of the frontal, the 
cribriform plate and crista galli of the ethmoid, the upper surface 
of the lesser wings of the sphenoid, and the anterior one-third 
of the upper surface of the body of the sphenoid. Those which 
form the middle fossa are the posterior two-thirds of the upper 
surface of the body of the sphenoid, the whole upper surface 
of the greater wing of the sphenoid, the anterior face of the 
petrous portion of the temporal, and the internal face of the 
squamous portion of the temporal. Those bones which form 
the posterior fossa are the posterior surface of the petrous por- 
tion of the temporal, the postero-inferior angle of the parietal, 
the internal surface of the mastoid portion of the temporal, 
and all of the anterior surface of the occipital which lies below 
the transverse groove for the lateral sinuses upon that bone. 
The appearances in the anterior fossa, on the mid-line, are 
the foramen caecum, the crista galli, the ethmoidal spine of the 
sphenoid and its articulation with the sphenoid notch of the 
ethmoid, the optic ridge, forming one of its boundaries, and 
the beginning of the longitudinal sinus. The lateral appearances 
are the grooves and three rows of foramina found upon the 
upper surface of the cribriform plate of the ethmoid, includ- 
ing the slits for the nasal nerves. Still further external are 
the internal openings of the anterior and posterior ethmoidal 
foramina, while external to them is the irregular upper surface 108 
DESCRIPTIVE ANATOMY. 
of the orbital plate of the frontal, at the posterior border of 
which may be seen the suture between that bone and the lesser 
wing of the sphenoid. 
In the middle fossa are seen the optic (chiasmatic) groove, 
the olivary process (tuberculum Sellae), and the sella Turcica, 
with the dorsum ephippii upon the mid-line extending to the 
basilar suture, forming the line of separation between the mid- 
dle and the posterior fossae. Laterally are seen in front the 
optic foramina leading outward and forward from the optic 
grooves, the anterior clinoid processes projecting backward and 
inward, behind and internal to these springing from the olivary 
ridge, the middle clinoid processes. External to and in front 
of these appearances is the anterior lacerated foramen, bounded 
above by the lower border of the lesser wing, below by the 
inner part of the upper border of the greater wing, and in- 
ternally by the body of the sphenoid. Behind and external to 
that is the foramen rotundum, still further behind and still 
further external the foramen ovale, and behind and external 
to that the foramen spinosum, while internal to this row of 
foramina is the italic-/-shaped groove for the carotid sinus, 
on the lateral aspect of the body of the sphenoid, guarded in 
front, at its commencement, by the lingula. Behind this is the 
upper opening of the middle lacerated foramen, external to 
which are the appearances seen on the anterior face of the 
petrous portion of the temporal, presenting from within out- 
ward the digital pit, the groove leading to the hiatus Fallopii, 
the petrosal groove, the bulge corresponding to the superior 
semi-circular canal, and the depression which corresponds to 
the tympanum and the orifice of the carotid canal. 
The posterior fossa presents on the mid-line the inclined 
plane formed by the grooved upper surface of the occipital, 
the foramen magnum, and the lower vertical limb of the occi- 
pital cross. Laterally are seen the appearances on the posterior 
surface of the petrous portion of the temporal, viz., the internal 
auditory meatus, the opening for the aqueduct of the vestibule, 
and occasionally a small depression for lodging a process of the 
dura mater, the posterior border of the petrous portion of the 
temporal, aiding in the formation of the jugular foramen, OSTEOLOGY. 
109 
marked by the triangular projection of bone which divides this 
foramen into two portions. External to this is the groove which 
enters into the formation of the lateral sinus, and which com- 
mences at the jugular foramen on the jugular process of the 
occipital bone, leaves that for the internal face of the mastoid 
portion of the temporal, leaves that bone to appear momentarily 
on the postero-inferior angle of the parietal, and then reappears 
upon the occipital bone, where it forms the superior boundary 
of the posterior fossa and terminates in the torcular Herophili, 
to the side of the anterior occipital protuberance. In the fora- 
men magnum can be seen the posterior openings of the anterior 
condyloid foramina. Below the lateral limbs of the occipital 
cross are the fossse which lodge the cerebellum. 
The Anterior Region of the Skull. 
The ANTERIOR REGION OF the SKULL (norma frontalis), or 
face, is bounded above by the superciliary ridges, below by the 
basilar border of the inferior maxilla, and laterally by a line 
drawn from the external angular process of the frontal bone 
through the angle of the inferior maxilla. It presents for ex- 
amination five cavities: two orbital, two nasal, and the oral. 
The oral, or buccal, cavity has been already described with 
the base of the skull and with the inferior maxilla itself. In 
the recent state other appearances than those named should be 
mentioned; but these are not seen in the dry preparation. 
The orbital cavities. Each orbit is an irregular four-sided 
pyramid, having, of course, four surfaces and four angles. The 
apex of the pyramid is directed backward and inward and the 
base forward and outward; a line drawn through the centre 
of each cavity and through the optic foramina, would meet that 
of the opposite side over the middle of the sella Turcica. The 
sides of these pyramidal cavities are superior, inferior, internal 
and external. The angles are supero-internal, supero-external, 
infero-internal and infero-external. These lines are formed 
by the articulations of the various bones which enter into the 
formation of the cavities. The supero-internal line is formed 
from before backward by the articulation of the internal angular 110 
DESCRIPTIVE ANATOMY. 
process of the frontal bone, and the upper extremity of the 
lachrymal; behind this by the superior border of the os planum 
of the ethmoid and the margins of the rectangular ethmoidal 
notch on the orbital plate of the frontal. In this angle are 
seen the anterior and posterior ethmoidal foramina. The sup e r o- 
external angle is formed by an irregular suture, commencing 
as an articulation between the external angular process of the 
frontal and the frontal process of the malar. Behind this is 
the orbital process of the malar still articulating with the frontal, 
and behind that the superior border of the anterior surface 
of the greater wing of the sphenoid, articulating with the orbital 
process of the frontal, and behind this the spheroidal fissure. 
The infero-internal angle is formed by the articulation of the 
lower extremity of the lachrymal with the inner border of the 
orbital face of the superior maxilla; behind this the lower 
border of the os planum of the ethmoid with the same face of 
the superior maxilla; and behind that the ethmoidal surface of 
the orbital process of the palate with the lateral mass of the 
ethmoid. The inf er o-external angle is formed by the suture 
between the maxillary process of the malar and the malar pro- 
cess of the superior maxilla, and behind these by the spheno- 
maxillary fissure. 
The superior wall is formed in front by the inferior surface 
of the orbital plate of the frontal; behind by the lower surface 
of the lesser wing of the sphenoid. The external wall is formed 
jointly by the internal face of the orbital process of the malar, 
and the anterior surface of the greater wing of the sphenoid. 
The inferior face is formed mainly by the orbital, or superior, 
surface of the superior maxilla; but towards its outer side the 
grooved portion of the orbital process of the malar enters into 
its formation. The most posterior portion of the inferior face 
is formed partly by the orbital process of the palate. The 
internal face is formed from before backward by the outer sur- 
face of the lachrymal and the outer face of the os planum of 
the ethmoid. Entering into this cavity are two foramina, the 
anterior and posterior ethmoidal, which establishes a means 
of communication between the anterior fossae of the skull and 
the cavity of the orbit. Posteriorly, directly at its apex, enters OSTEOLOGY. 
111 
the foramen opticum, and below this is seen the anterior lacer- 
ated foramen, formed between the inferior border of the lesser 
wing of the sphenoid and the superior border of the superior 
surface of the greater wing. This foramen is triangular in 
outline, its apex directed upward and outward, and its base 
downward and inward, and communicates at an acute angle 
with a fissure found at the infero-external angle, called the 
spheno-maxillary. This fissure is bounded above by the lower 
border of the anterior face of the greater wing of the sphenoid, 
below by the postero-external border of the orbital face of the 
superior maxilla. Anteriorly it is usually bounded by the non- 
articular portion of the posterior border of the orbital process 
of the malar; but occasionally the border is articular, when the 
malar does not enter into the formation of the foramen. On 
the external wall may be seen a vertical suture extending be- 
tween the posterior border of the orbital process of the malar 
and the external border of the anterior face of the sphenoid. 
Running through this wall are two minute foramina, trans- 
mitting branches of the fifth nerve called the temporo-malar 
foramina. On the inner wall are from before backward, the 
groove for the lachrymal duct, the vertical ridge of the lach- 
rymal bone and the suture between that bone and the os planum. 
On the floor of the orbit, near its posterior extremity, is seen 
a slight groove, which about the middle of the floor is con- 
verted into a foramen by plunging beneath the orbital surface 
of the superior maxilla. This canal continues its course until 
it passes beneath the infra-orbital margin, and terminates on 
the anterior surface of the face. It is known as the infra-orbital 
groove, infra-orbital canal and infra-orbital foramen in the three 
respective places. On the roof of the orbit is seen near the 
internal angular process of the frontal bone a slight projec- 
tion or sometimes a slight depression, the fovea trochlearis. 
External to this is an aperture which passes through above the 
margin of the orbit, and is known as the supra-orbital foramen. 
External to this and just behind the external angular process 
is the most depressed portion of the orbital cavity, forming a 
fossa in which is lodged the lachrymal gland, the fossa being 
known as the fossa lachrymalis. 112 
DESCRIPTIVE ANATOMY. 
Below the orbit is the roughened projection of the malar pro- 
cess of the superior maxilla, while external to it are seen the 
external openings of the temporo-malar foramina. Below the 
inferior orbital foramen is a depression called the incisive fossa. 
Above the orbits are seen the supra-orbital ridges, and in the 
mid-line the nasal prominence, or glabella. Below are the 
roughened surfaces of bone for the attachment of the various 
muscles of expression. 
The nasal fossae are two irregular cavities situated in the 
face and extending from the anterior to the posterior nares. 
Each anterior aperture is bounded above by the lower end of 
a nasal bone; externally by the anterior border of the nasal 
process of the superior maxilla; below by the concave, free, 
sharp border of the palate process of the superior maxilla; 
internally by a broad triangular space, filled, in the recent 
state, by a triangular plate of cartilage. The posterior nares 
are bounded internally by the free, concave, posterior border 
of the vomer; externally by the inner surface of the internal 
pterygoid plate;; inferiorly by the posterior, concave border of 
the horizontal portion of the palate bone; above by the lower 
surface of the alae of the vomer, the sphenoidal process of the 
palate and the lower face of the body of the sphenoid. The 
septum between the two is formed, above, by the perpendicular 
lamella of the ethmoid bone, below and posteriorly by the vomer, 
and the angular interval left between the two, in front, is filled 
in by a triangular plate of fibro-cartilage, called the cartilage 
of the septum. Each fossa presents for examination four walls. 
The inner wall is formed by the septum. The outer wall is 
formed by the superior maxilla, the inferior turbinated, the 
lachrymal, the ethmoid, the palate and the internal pterygoid 
plate of the sphenoid. The roof is formed by the nasal, the 
frontal, the ethmoid and the body of the sphenoid. The floor 
is formed in front by the palate process of the superior maxilla 
and completed behind by the horizontal plate of the palate bone. 
The external wall of each fossa is very uneven, presenting 
three shell-like projections, the turbinated bones, overhanging 
small spaces called meatuses. The inferior turbinated is the 
roof of the inferior meatus, whose floor is the floor of the nasal OSTEOLOGY. 
113 
cavity. At the anterior extremity of the inferior meatus is 
the opening of the winding canal, the nasal, conveying the lach- 
rymal duct from the orbit. Between the upper aspect of the 
inferior, and the lower of the middle turbinated bones, lies a 
smaller space, the middle meatus. Near the middle of this 
space is the irregular opening, often two, of the antrum max- 
illare, more anteriorly and near the upper part is the opening 
into the anterior ethmoidal cells, through which the middle 
meatus communicates by a tortuous canal called infundibulum, 
with the frontal sinuses. The superior meatus lies between 
the superior and middle turbinated bones, and can be seen only 
by looking through the posterior nares. Its walls are formed 
mainly by the various parts of the ethmoid. In the back part 
of this space is the openings of the sphenoidal sinus, while in 
front of this are the openings of the spheno-palatine foramen 
and the posterior ethmoidal cells. 
The roof of the nose slopes upward and backward as far as 
the nasal bone extends, then runs straight backward, where it 
is formed by the cribriform plate of the ethmoid, and turns 
downward and backward when the sphenoid enters into its 
formation. 
The floor is concave from side to side, runs abruptly down- 
ward from the anterior border, and then straight backward to 
its termination. It is marked near the septum by the superior 
opening of the anterior palatine foramen. About at its posterior 
one-third is the transverse suture between the horizontal plate 
of the palate process of the superior maxilla. 
Articulation of the Bones of the Skull-Occipital Bone. 
The occipital bone articulates by its two condyles with the 
atlas; by its superior border with the two parietal bones, form- 
ing the lambdoid suture; by the outer half of each inferior border 
with the posterior border of the mastoid portion of the tem- 
poral bone, and by the inner half with the posterior border of 
the petrous portion; by the basilar process with the posterior 
surface of the body of the sphenoid bone, forming the basilar 
suture. 114 
DESCRIPTIVE ANATOMY. 
Parietal Bone. 
The parietal bone articulates by its upper border with its 
fellow, forming the sagittal suture; by its lower border with the 
upper part of the semi-circular border of the squamous portion 
of the temporal bone, forming the squamous suture; by its 
posterior border with the upper border of the occipital; by its 
anterior border, with one-half of the semi-circular border of the 
frontal, forming one-half of the coronal suture; by its anterior 
inferior angle, with the upper border of the outer surface of 
the greater wing of the sphenoid; by its posterior inferior angle, 
with the upper border of the mastoid portion of the temporal 
bone. 
Frontal Bone. 
The FRONTAL bone articulates by its superior, or semi-circular 
border with the anterior border of the two parietal bones; by 
the posterior border of each orbital plate with the lesser wing 
of the sphenoid; by the'triangular surface, i. e., the sphenoidal 
triangle of the frontal, at the junction of the straight and semi- 
circular borders, with the frontal triangle of the sphenoid; by 
the circumference of the ethmoidal fissure with the lateral and 
anterior borders of the cribriform plate of the ethmoid; by the 
front of the fissure with the alae of the crista galli; by the 
outer border of the notch with the upper border of the os 
planum of the ethmoid; by the internal angular process with 
the lachrymal bone; by the nasal notch with the nasal bones 
and the nasal process of the superior maxillary; by the nasal 
spine with the crest of the nasal bones, in front, and with the 
upper part of the anterior border of the perpendicular lamella 
of the ethmoid, behind; by the internal angular process with the 
lachrymal bone; by the external angular process with the frontal 
process of the malar bone, and by the part just behind this with 
the orbital process of the malar. OSTEOLOGY. 
115 
Temporal Bone. 
Squamous portion. The squamous portion articulates by the 
upper part of its semi-circular border with the lower border 
of the parietal bone; by the front part of the same border with 
the outer border of the upper surface of the greater wing of 
the sphenoid; by the anterior part of the glenoid fossa with the 
condyle of the inferior maxilla; by the extremity of the zygo- 
matic process with the zygomatic process of the malar bone. 
Mastoid portion. By its upper border with the posterior 
inferior angle of the parietal; by its posterior border with the 
outer half of the lower border of the occipital bone. 
Petrous portion. The petrous portion articulates by its pos- 
terior border with the inner half of the lower border of the 
occipital bone; by its anterior border with the posterior border 
of the upper surface of the greater wing of the sphenoid. 
Sphenoid Bone. 
Body. By the posterior surface of the body with the basilar 
process of the occipital; by the ethmoidal spine with the sphe- 
noidal notch of the cribriform plate of the ethmoid; by the 
crest with the upper part of the posterior border of the per- 
pendicular lamella of the ethmoid; by the surface on each side 
of the crest with the posterior extremity of the lateral mass 
of the ethmoid, through the medium of the pyramid of Wistar, 
by which it also articulates with the posterior surface of the 
orbital process of the palate; by the rostrum and vaginal pro- 
cesses with the upper border of the vomer, and by its under 
surface with the sphenoidal process of the palate. 
Greater Wing. By the posterior border of its upper surface 
with a portion of the anterior border of the petrous portion of 
the temporal; by the external border of the superior surface 
(or the posterior border of the external surface) with the 
semi-circular border of the squamous portion of the temporal; 
by the superior border of the external face with the anterior 
inferior angle of the parietal, and with the outer part of the 
sphenoidal triangle of the frontal; by the anterior border of 116 
DESCRIPTIVE ANATOMY. 
the outer face with the posterior border of the orbital process 
of the malar; by the frontal triangle lying just internal to the 
upper border of the outer surface with the sphenoidal triangle 
at the junction of the vertical and horizontal plates of the 
frontal. 
Lesser Wing. By its anterior border with the posterior border 
of the orbital plate of the frontal. 
Pterygoid process. By its anterior border with the posterior 
border of the perpendicular plate of the palate; by the triangular 
interval between the lower part of its two plates with the 
tuberosity of the palate; by the inner side of its base with the 
posterior part of the outer surface, and posterior border of 
the sphenoidal process of the palate; by its inner face with 
the posterior part of the outer face of the vertical plate of the 
palate. 
Ethmoid Bone. 
Horizontal plate. By its lateral and anterior borders with 
the cerebral border of the ethmoidal fissure of the frontal. 
By the crista galli with anterior border of ethmoidal notch form- 
ing foramen coecum. By the sphenoidal notch with the eth- 
moidal spine of the sphenoid. 
Perpendicular lamella. By the upper part of its posterior 
border with the crest of the sphenoid; by the lower part of its 
posterior border with the upper part of the anterior border of 
the vomer; by the upper part of its anterior border with the 
nasal spine of the frontal; by the lower part of its anterior 
border with the crest of the nasal bones. 
Lateral mass. By its upper surface it is continuous with 
the lower surface of the horizontal plate, and the half cells 
on the orbital plate of the frontal; by its posterior extremity 
with the anterior face of the body of the sphenoid bone, 
through the medium of the pyramid of Wistar; by its anterior 
extremity with the inner face of the lachrymal bone and with 
the inner face of the nasal process of the superior maxillary; 
by the upper border of the os planum with the orbital margin 
of the horizontal plate; by the lower border of the os planum 
with the inner border of the orbital face of the superior maxil- OSTEOLOGY. 
117 
lary bone, and behind that with the orbital process of the 
palate bone; by the posterior border of the os planum with the 
front of the body of the sphenoid; by the anterior border of 
the os planum with the posterior border of the lachrymal bone; 
by the part below the os planum with the inner face of the 
superior maxillary bone; by the unciform process with the 
ethmoidal process of the inferior turbinated bone; by the an- 
terior extremity of the middle turbinated bone with the superior 
turbinated crest of the nasal process of the superior maxillary; 
by the posterior extremity of the middle turbinated bone with 
the superior turbinated crest of the vertical plate of the palate 
bone. 
Nasal Bone. 
By its upper border with the nasal notch of the frontal bone; 
by its outer border with the nasal process of the superior maxil- 
lary; by its inner border with its fellow; by the crest of the 
two bones, above with the nasal spine of the frontal; below, 
with the lower part of the anterior border of the perpendicular 
lamella of the ethmoid. 
Superior Maxillary. 
The superior maxillary bone articulates by its body and 
processes. 
Body. By the lower part of its posterior border with the front 
of the tuberosity of the palate bone; by the internal border 
of its orbital surface, from before backwards, with the lower 
border of the lachrymal bone, the os planum of the ethmoid 
and the anterior face of the orbital process of the palate bone. 
Antero-externally the orbital face articulates with the lower 
border of the orbital process of the malar; by its internal face 
the body articulates by the part posterior to the aperture of 
the antrum with the anterior border, the maxillary process 
and most of the outer surface of the vertical plate of the palate; 
above the aperture with the outer surface of the lateral mass 
of the ethmoid, below the os planum; below the aperture with 
the maxillary process of the inferior turbinated bone; in front DESCRIPTIVE ANATOMY. 
118 
of the aperture with the projection on the anterior border of 
the lachrymal and the lachrymal process of the inferior tur- 
binated; by the inferior turbinated crest with the anterior ex- 
tremity of the inferior turbinated. 
Malar process. By the malar process with the maxillary 
process of the malar. 
Palate process. By the inner border of the palate process 
with the inner border of the opposite palate process and with 
the anterior part of the lower border of the vomer; by its 
posterior border with the anterior border of the horizontal 
plate of the palate. 
Nasal process. By its upper border with the nasal notch 
and internal angular process of the frontal; by the inner edge 
of its posterior border with the anterior border of the lachrymal 
and by the lachrymal tubercle with the hamular process of the 
lachrymal; by the upper part of its internal surface with the 
anterior extremity of the lateral mass of the ethmoid; by the 
superior turbinated crest with the anterior extremity of the 
middle turbinated bone; by its anterior border with the posterior 
border of the nasal bone. 
Palate Bone. 
The palate bone articulates by its two plates. By its pro- 
cesses and tuberosity. 
The horizontal plate articulates by its inner border with the 
opposite bone and with the posterior part of the lower border 
of the vomer; by its anterior border with the posterior border 
of the palate process of the superior maxillary. 
The perpendicular plate articulates by most of its external 
surface, its anterior border and maxillary process with the inner 
face of the body of the superior maxillary, behind the aperture 
into the antrum; by its posterior border and that part of the 
outer face behind the non-articular surface, with the inner face 
of the pterygoid process; by its superior turbinated crest with 
the posterior extremity of the middle turbinated bone; by its 
inferior turbinated crest with the posterior extremity of the 
inferior turbinated bone; by the anterior face of the tuberosity 
with the lower part of the posterior border of the body of the OSTEOLOGY. 
119 
superior maxillary and by its posterior face with the lower 
part of the anterior edge of the two pterygoid plates filling in 
the gap between them; by the anterior face of its orbital pro- 
cess with the posterior part of the internal border of the orbital 
face of the body of the superior maxillary; by its internal face 
with the external surface of the lateral mass of the ethmoid, 
below and behind the os planum; by its posterior face with 
the front of the body of the sphenoid, through the pyramid of 
Wistar. By the upper surface of the sphenoidal process with the 
lower surface of the vaginal process of the sphenoid; by its 
posterior border and the posterior parts of its outer face with 
the inner side of the base of the pterygoid process of the 
sphenoid. 
Vomer. 
The vomer articulates by its borders. 
By the groove on its upper border with the rostrum of the 
sphenoid; by its alae with the opposing faces of the vaginal 
process and lower surface of the body of the sphenoid; by its 
lower border, posteriorly, with the crested inner border of the 
horizontal plate of the palate and anteriorly with rhe crested 
inner border of the palate process of the superior maxillary; 
by the upper part of the anterior border with the lower part 
of the posterior border of the perpendicular plate of the ethmoid. 
Inferior Turbinated Bone. 
By its anterior extremity with the inferior turbinated crest 
of the superior maxillary; by its posterior extremity with the 
inferior turbinated crest of the palate; by the lachrymal pro- 
cess with the edges of the lachrymal sulcus of the inner face of 
the body of the superior maxillary and with the projection on 
the anterior border of the lachrymal; by the maxillary process 
with the lower margin of the aperture of the antrum; by the 
ethmoidal process with the unciform process of the ethmoid. 120 
DESCRIPTIVE ANATOMY. 
Lachrymal Bone. 
The lachrymal bone articulates by its upper extremity with 
the internal angular process of the frontal; by its posterior 
border with the anterior border of the os planum; by its lower 
extremity with the front part of the internal border of the 
orbital plate of the superior maxillary; by the anterior border 
with the inner edge of the posterior border of the nasal process 
of the superior maxillary and by the projection from the lower 
end of this border with the edges of the lachrymal sulcus on 
the inner face of the body of the superior maxillary and with 
the lachrymal process of the inferior turbinated bone and by 
the back part of the internal surface with the anterior extremity 
of the lateral mass of the ethmoid. 
Zygomatic Bone. 
The zygomatic or malar bone articulates by its processes 
and by the anterior border of its body, which articulates with 
the anterior border of the malar process of the superior maxil- 
lary. 
By the frontal process with the external angular process of 
the frontal. 
By the maxillary process with the malar process of the 
superior maxillary. 
By the zygomatic process with the zygomatic process of the 
temporal bone. 
By the orbital process; the lower border articulates with the 
orbital surface of the superior maxillary, antero-extertially; 
by the posterior border, with the outer border of the orbital 
plate of the greater wing of the sphenoid; and by the upper 
border with the frontal behind the internal angular process. 
Inferior Maxillary Bone. 
The inferior maxillary bone articulates by its condyles with 
the anterior part of the glenoid fossa of the temporal bone. SYNDESMOLOGY. 
121 
SYNDESMOLOGY. 
The study of joints, or articulations, is the study of the rela- 
tion between bones, more particularly of the surfaces of apposi- 
tion, and the means by which the bones are held together and 
at the same time permitted to move upon one another. In the 
study of osteology it has been seen that the articular surfaces of 
the different bones present widely varying appearances; upon 
these differences depends the classification of joints. In some 
joints the opposing surfaces present inter-locking, tooth-like 
processes, so that the union of the bones results in an immova- 
ble joint. This form of articulation is called synarthrosis. 
The contiguous surfaces may be roughened, showing the at- 
tachment of ligamentous fibres passing directly between the 
bony faces; or the fibres may have been attached through the 
medium of cartilage coating the bony surfaces. This indicates 
a joint in which motion is very slight, consisting of a twisting 
of the ligamentous fibres; and the articulation is known as 
amphiarthrosis. 
The bony surfaces, lastly, may be smooth and polished, as a 
result of mutual friction-indicating a freely movable joint of 
the class called diarthrosis. 
The three classes of joints, then, are: 1st, Synarthrodical, or 
immovable joints; 2d, Amphiarthrodial, or partially movable, 
and 3d, Diarthrodial, or freely movable joints. 
Besides the bones, there are other structures which con- 
tribute to the formation of a joint, as follows: In the amphiar- 
throdial and diarthrodial joints, the bones are held together 
by ligaments. In the amphiarthrodial these not only pass from 
bone to bone, exterior to the joint, but directly between the 
bones, within the joint, forming what are called interosseous 
ligaments. In the diarthrodial joints, as a rule, no ligamentous 
fibres are attached to the articulating surfaces of the bones; 
the ligaments, more or less completely surrounding the joint, 
are attached to both bones beyond the articular surfaces. The 
fibres may entirely surround the joint forming a capsular liga- 
ment, or they may be gathered into separate bundles. 122 
DESCRIPTIVE ANATOMY. 
In the diarthrodial joints the opposing bony surfaces are 
coated by encrusting, or articular cartilage, which, on its deep 
face, is firmly attached to the bone, and presents a perfectly 
smooth, free surface towards the opposing bone. 
In order to lessen friction, and render motion entirely easy, 
diarthrodial joints possess a secreting, serous-like membrane, 
called the synovial membrane, which secretes a viscid, glairy 
fluid, called synovia. The synovial membrane, in very early 
life, is said to be a closed sac, coating the entire joint; but soon 
the portion covering the encrusting cartilage is worn away, or 
becomes inconspicuous. 
If joints are subject to very frequent motion, the effect of 
friction is further guarded against by a plate of fibro-cartilage, 
called the inter-articular cartilage. This is a more or less flat, 
circular plate of cartilage interposed between the encrusting 
cartilage of the bony surfaces, and attached only by its cir- 
cumference to the ligaments. When this exists entire, the joint 
will have two synovial membranes, but occasionally the plate is 
worn through and then, the two membranes communicating, 
there is virtually but one. 
Synarthrodial Joints. 
The immovable joints are almost confined to the bones of the 
skull, the articulations between which are generally called 
sutures. 
There are four varieties of suture: 1st, Dentate, or serrate, 
in which edges of the bones present interlocking processes, 
called dentate when long and tooth-like, and serrate when short, 
like the teeth of a saw; 2d, Suture by harmony, in which two 
roughened surfaces come in contact, as the inner border of the 
palate processes of the two superior maxillary bones; 3d, Schin- 
dylesis, where the edge of one bone is received in a groove in 
another, as the articulation between the vomer and the sphenoid; 
4th, Gomphosis, where a bone is received into a corresponding 
cavity in another. This term is applied to the union between 
the teeth and their sockets, and is really no articulation. SYNDESMOLOGY. 
123 
Diarthrodial Joints. 
The diarthrodial joints, in accordance with the varying shape 
of the articular surfaces, are divided into six varieties: 
1st. Arthrodial, formed by more or less flat, plane surfaces, 
so that motion is much restricted. 
2d. Hinge or trochlear, or ginglymoid, characterized by the 
presence of a pulley on one of the articular surfaces. In this 
joint motion can occur, as a rule, in only two directions. 
3d. Condyloid, in which one element is a condyle, the other 
a proper receiving cavity. These joints are capable of very 
free movement. 
4th. Saddle-shaped, or concavo-convex, joints, or joints by 
reciprocal reception, where both surfaces are saddle-shaped and 
mutually interlock. The examples of this form of joint are 
sterno-clavicular, trapezio-metacarpal, and calcaneo-cuboid. 
5th. Pivot, or trochoid joints.-There are only two of these, 
atlo-axoid and radio-ulnar. They present an osseo-ligamentous 
ring, in which a part of one bone is received; this, in the first 
example, acting as a pivot around which the other bone revolves; 
while, in the second case, it rotates on its own axis. 
6th. Ball and socket, or enarthrodial joints.-These present a 
more or less spherical head, as one contribution while a receiv- 
ing cavity is the other. The two important examples of this 
variety are the shoulder and hip, in both of which motion is 
very free. 
In describing a joint, the following heads have to be con- 
sidered : 
1st. The class and variety. 2d. The bony contributions. 3d. 
The ligaments. 4th. The synovial membrane. 5th. The inter- 
articular cartilage, perhaps. 6th. The movements and mechan- 
ism of movement of which the joint is capable. 7th. The muscles 
which strengthen the joint, if any. 8th. The nerves and arteries. 
As numerous as the motions seem to be, they can all be re- 
ferred to the following: 
(a) Gliding, which occurs to some extent in all diarthrodial 
joints, but is peculiarly characteristic of the arthrodial. It con- 
sists of the slipping of one surface on another. 124 
DESCRIPTIVE ANATOMY. 
(b) Flexion-angular movement of a segment of the body 
in an antero-posterior vertical plane, generally forward, but in 
some cases backward. 
(c) Extension-the reverse of flexion. 
(d) Abduction-the movement of a segment away from some 
established mid-line, generally that of the body. 
(e) Adduction-the reverse of abduction. 
(/) Circumduction-the partial performance in rapid and 
regular succession of the four preceding movements, passing, 
in inward circumduction, from flexion to adduction, to exten- 
sion, to abduction, and again to flexion. In outward circumduc- 
tion the order is reversed. In the performance of this move- 
ment, the moving segment circumscribes a cone-shaped space, 
the apex of which is at the joint and the base at the distal ex- 
tremity of the moving segment. 
(g) Revolution, or false rotation. This occurs at but two 
joints, the atlo-axoid and radio-ulnar. In the first case, the 
atlas revolves around the odontoid process as an axis; in the 
latter the radius rotates around its own axis in the ring formed 
by the orbicular ligament and the lesser sigmoid cavity. 
(h) Rotation, or true rotation. This is almost limited to two 
joints, the shoulder and the hip, and, as it happens, can be de- 
fined in the same terms for both, viz., movement outward or in- 
ward around a line drawn from the innermost point of the 
humerus or femur, to the innermost point of the inner condyle 
of either bone. 
The Articulations of the Vertebral Column. 
The articulations of the spinal column may be divided into 
those of the Column in general, the Atlo-axoid, the Occipito- 
atloid, the Sacro-vertebral. 
Articulations of the Spine in General. 
Each vertebra articulates with the vertebra above and the 
one below by a joint of the diarthrodial class, and arthrodial 
variety, on each side, formed by the inferior and superior articu- 
lar processes. The ligaments are capsular around the articulat- SYNDESMOLOGY. 
125 
ing surfaces, and those which bind the same segments of the 
different vertebrae together, i. e., the intervertebral disks, the 
anterior and posterior common, intertransverse, supra- and in- 
ter-spinous and ligamenta subflava of the laminae. These liga- 
ments are collectively known as the common ligaments of the 
spine. 
Articulation of the Articular Processes. 
The articulation between contiguous articular processes is 
a diarthrodial joint of the arthrodial variety, presenting a syno- 
vial membrane and one ligament, an imperfect capsular liga- 
ment, attached beyond the margins of the opposing articular 
surfaces. 
The Ligaments of the Spine in General-Ligaments of the Bodies. 
The bodies of the vertebrae are connected by means of inter- 
vertebral disks and anterior and posterior common ligaments. 
The intervertebral fibro-cartilage is found lying between the 
opposing surfaces of two adjacent vertebrae, firmly adherent to 
each. In shape it corresponds exactly with the bodies between 
which it lies; in thickness it varies with the different regions of 
the spine. Collectively, the disks form about one-fourth the length 
of the column and they are found between all the bodies except 
the first and second, being absent there because the atlas has no 
body. It is formed externally of concentric laminae of fibrous 
tissue and fibro-cartilage, the centre of the disk being a soft, 
pulpy mass. 
Some of the fibres extend from the upper surface of the verte- 
bra below to the lower surface of the vertebra above; and these 
fibres are crossed in the form of the letter X, so that when the 
body bends or twists to either side the cords of the fibres may 
twist and untwist as the occasion demands. 
The anterior common or longitudinal ligament is found de- 
scending along the front of the bodies from the axis to the 
sacrum, widening as it descends. As a matter of fact this liga- 
ment extends to the basilar process of the occipital bone; but 
it has been customary to consider the upper portion, extending 126 
DESCRIPTIVE ANATOMY. 
from the axis to the occipital bone, as a separate ligament. It 
is composed of superimposed layers of fibres, the deepest of 
which are attached simply to the bodies of adjacent vertebrae, 
while the next layer of fibres extends over two or three verte- 
brae, and the most superficial extends over four or five. This 
ligament widens as it descends, is not attached over the centres 
of the bodies of the vertebrae, where it leaves a slight space be- 
tween itself and the bodies, but is attached to the lips of the 
vertebrae and to the intervertebral disks. A few scattered fibres 
continue this ligamentous band around the bodies of the vertebrae 
to the transverse processes. 
The posterior longitudinal ligament lies within the spinal 
canal, and is attached to the bodies of the vertebrae, extending 
from the axis to the sacrum. Just as in the case with the ante- 
rior common ligament, this in reality extends to the cranium; 
but the upper portion of it is known under a separate name. 
Like the anterior it consists of several layers of fibres; but 
unlike that ligament it narrows as it descends; and instead of 
having straight edges, it is scalloped, widening over each inter- 
vertebral disk and narrowing over the body. It is thinner and 
less powerful than is the anterior common ligament. 
Ligaments of the Laminae. 
The ligaments that bind the laminae together consist of yellow 
ligamentous fibres, called the ligamenta flava. By their upper 
extremity they are attached to the anterior surface of the lamina 
above, and by their lower extremity they are attached to the 
posterior surface and upper border of the one below. This is 
necessitated by the imbricated arrangement of the lamina. They 
are thicker in the loins than in the back and neck. 
Ligaments of the Spinous Processes. 
The spinous processes are connected by two ligaments, the 
supra- and inter-spinous. The supraspinous is a round cord 
which extends from the seventh cervical vertebra to the sacrum, 
attached to the tips of the spinous processes. This cord is con- SYNDESMOLOGY. 
127 
tinued upward, from the seventh cervical vertebra to the pos- 
terior occipital protuberance, by a more prominent band, which 
has received the name of the ligamentum nuchae (L. nucha, 
a nape.) This, in man, is composed almost entirely of fibrous 
tissue, and is simply a division of the supra-spinous ligament. 
The inter-spinous ligament consists of thin fibres, which are at- 
tached to the adjacent edges of the spinous processes, and is 
found only in the dorsal and lumbar regions. 
Ligaments of the Transverse Processes. 
Only in the lower dorsal and lumbar regions are the transverse 
processes held together by a few scattered intermediate fibres, 
called inter-transverse ligaments, extending between the adja- 
cent edges of the corresponding transverse processes. 
The Articulation of the Head with the Spine, and the First with the 
Second Cervical Vertebra. 
The Atlo-Axoid Articulation. 
The articulation between the atlas and the axis consists of 
a diarthrodial and arthrodial joint on each side, formed by the 
articular process, as seen between other vertebrae, and of a 
pivot joint, in front, between the posterior face of the anterior 
arch of the atlas and the front of the odontoid process of the axis. 
Two anterior atlo-axoid. 
Transverse. 
Two capsular. 
Posterior atlo-axoid. 
Crucial. 
The anterior atlo-axoid ligament, usually described as two, 
consists of a broad band of ligamentous fibres attached below 
to the front of the body of the axis as far up as the base of the 
odontoid process, and above to the lower border, anterior sur- 
face and tubercle of the anterior arch of the atlas. That part 
occupying the middle line is thicker than the lateral fibres and DESCRIPTIVE ANATOMY. 
128 
is described as a separate ligament. It is merely a continuation 
of the anterior common ligament of the spine. 
The posterior atlo-axoid ligament is a membrane-like fold 
closing in the space between the vertebrae behind. It is attached 
above to the posterior surface and lower border of the posterior 
arch, extending from the capsular ligament of one side to that 
of the other and blending with the capsules. Below it seizes the 
laminae of the axis. It corresponds to the ligamenta subflava of 
other vertebrae. 
The transverse ligament is a strong band, broader in the 
centre than at either extremity, attached firmly by either end 
to the inner face of the lateral mass of the atlas, stretching 
across the odontoid process and firmly binding the latter to the 
anterior arch of the atlas. The shortest fibres are below where 
they form a constricting band around the neck of the odontoid 
process. As it passes over the odontoid process a vertical band 
of fibres crosses it, some of them derived from the transverse 
ligament, to be attached by one end to the base of the odontoid 
process and by the other to the basilar process of the occipital. 
This gives the ligament'the form of a cross, hence its name, 
crucial ligament. 
The two capsular ligaments are attached around the margins 
of the articular facets on the two vertebrae, blending with the 
posterior atlo-axoid ligament. 
There are four synovial sacs connected with the articulation. 
Two belong to the joints formed by the articular processes, one 
is interposed between the front of the odontoid process and the 
facet on the anterior arch of the atlas, while one interposes 
between the posterior face of the odontoid process and the front 
of the transverse ligament. 
The Occipito-Atloid Articulation. 
This is a movable joint of the condyloid variety, the articulat- 
ing surfaces being the two condyles of the occipital above and 
the superior articular facets of the atlas below. The ligaments, 
seven in number, are: SYNDESMOLOGY. 
129 
Posterior atlanto-occipital. 
Two anterior atlanto-occipital. 
Two lateral atlanto-occipital. 
Two capsular. 
The central part of the (interior atlanto-occipital ligament is 
a rounded cord attached below to the tubercle on the anterior 
arch of the atlas and above to the under face of the basilar pro- 
cess of the occipital. The lateral portion of the ligament is a 
broad and thin band attached above to the margin of the fora- 
men magnum and below to the anterior arch of the atlas, ex- 
tending to the beginning of the capsular ligaments, with which 
it blends. They are the upward continuation of the anterior 
atlo-axoid, and through it of the anterior common ligament of 
the spine. 
The posterior atlanto-occipital is a broad and thin membranous 
band attached above around the margins of the foramen mag- 
num and below to the upper border and posterior surface of the 
posterior arch of the atlas. It corresponds to the ligaments 
between the laminae in the vertebral column, but contains no 
elastic fibres. 
The capsular ligaments are attached around the margins of 
the condyles above and the receiving surfaces on the atlas below. 
Behind and in front they blend with the anterior and posterior 
ligaments. 
The two lateral ligaments blend with the sides of the two 
capsular ligaments and are attached below to the transverse 
process of the atlas, extending above to the jugular process of 
the occipital bone. 
The Occipito-Axoid Ligaments. 
The occipito-axoid, ligament (membrano tectoria) is a broad 
membranous band which continues the posterior common liga- 
ment of the spine upward to the occipital. It is attached below 
by some fibres to the body of the third cervical vertebra and to 
the body of the axis. Passing upward it covers over the odon- 
toid process and the crucial ligaments and is attached to the 
anterior margin of the foramen magnum, passing upon the 
basilar process to blend with the dura. DESCRIPTIVE ANATOMY. 
130 
The odontoid or check ligament (alar ligaments) consists of 
three parts. The lateral portions are attached below to the pit 
on the side of the odontoid process and above to depressions 
found on the inner face of the condyles. The central portion 
is attached below to the tip of the odontoid process and above 
to the margin of the foramen magnum. 
Arteries and nerves. The vertebral artery supplies both of 
these articulations. The loop between the first and second cer- 
vical nerves supplies the articulation between the axis and the 
atlas, while the sub-occipital supplies the occipito-atloid articu- 
lation. 
The Articulations of the Pelvis, 
The articulations of the pelvis are four, viz., that between 
the fifth lumbar vertebra and the sacrum, that between the 
sacrum and coccyx, that between the sacrum and the os in- 
nominatum of each side and that between the two ossa innomi- 
nata. 
Sacro-Vertebral Articulation. 
The joint between the sacrum and last lumbar vertebra is 
similar to that between two vertebrae, the articulating surfaces 
being the articular processes of the two bones. The ligaments 
are the same as between any two vertebrae, with the addition 
of two ligaments on each side, the ilio-lumbar and lumbosacral, 
which are generally considered among the ligaments of the 
pelvis. 
The ilio-lumbar extends from the transverse process of the 
fifth lumbar vertebra outward to the ilium just above and in 
front of the ear-shaped articular surface. 
The lumbosacral passes from the transverse process of the 
fifth lumbar vertebra downward and outward to the wing of 
the sacrum. 
Sacro-Coccygeal Ligaments. 
The SACRO-COCCYGEAL ligaments are an intervertebral disk, 
small and insignificant, and an anterior, posterior and lateral 
ligaments passing directly from one bone to the other. SYNDESMOLOGY. 
131 
Sacro-iliac Ligaments. 
The sacro-iliac articulation, symphysis or synchondrosis, is 
formed by the auricular facets found on the sacrum and ilium, 
each of which is coated, in the recent state, by a thin plate of 
cartilage. The ligaments of the joint are an anterior and a 
posterior and the two sacro-sciatic, greater and lesser. 
The anterior sacro-iliac ligament is a thin plane of fibres 
passing from the front of the sacrum to the inner face of the 
ilium. 
The posterior sacro-iliac ligament is a dense and thick mass 
of fibres, both oblique and horizontal, passing between the con- 
tiguous surfaces of the two bones and filling in the deep depres- 
sion which exists between them. The fibres are attached to 
the rough surface on the ilium behind the auricular facet and 
to the similar depression on the lateral aspect of the sacrum 
as well as to the posterior face of the latter bone. 
The greater sacro-sciatic ligament (ligamentum sacro-tuber- 
osum) is attached by its posterior extremity to the posterior in- 
ferior spinous process of the ilium, and to the side and posterior 
face of the sacrum and coccyx. Passing forward it runs below the 
spine of the ischium and is attached to the tuberosity of the 
ischium, its inner edge being free and curved upward upon itself. 
The lesser sacro-sciatic ligament (ligamentum sacro-spin- 
osum) is blended with part of the greater at its posterior ex- 
tremity, being attached to the side of the sacrum and coccyx, 
slightly in front of the greater, and not extending so high up as 
the former. In front it is attached to the spine of the ischium. 
The lesser sacro-sciatic ligament forms the lower boundary 
of the greater sacro-sciatic foramen; while that part of the 
greater sacro-sciatic, which extends from the point where the 
two ligaments separate to the tuberosity of the ischium, forms 
the lower boundary of the lesser sacro-sciatic foramen. 
The Symphysis Pubis. 
The articulation between the ossa innominata is formed be- 
tween the two pubic bones, and is known as the symphysis pubis. 132 
DESCRIPTIVE ANATOMY. 
Each bone presents an oval articular surface, whose long 
diameter is downward and backward, coated by a thin plate 
of encrusting cartilage. The two plates are in contact only at 
the back part, leaving, in front, a wedge-shaped space filled by 
fibres passing between the two plates. Besides this inter-articu- 
lar ligament, there are four others-superior, consisting of fibres 
passing between the two bones above; inferior fibres, passing 
between the two bones below, and filling in the interval between 
the two rami, so as to form a smoothly-curved arch; anterior, 
fibres passing between the bones in front; and posterior, con- 
sisting of similar fibres behind. 
Arteries and Nerves. The articulations are supplied by 
branches from the lateral sacral, ilio-lumbar, middle sacral and 
internal pubic arteries. 
The nerves are received from the cords of the sacral plexus. 
Action. Movement between the occipital and the atlas is 
mainly confined to the backward and forward movements, 
though lateral movement is permitted to some extent. In the 
nodding movements of the head, flexion and extension, the con- 
dyles of the occipital glide backward and forward on the articu- 
lar surfaces of the atlas. Thus, in flexion the chin is carried 
toward the chest, while the condyles pass forward in their 
articular cavities. In extension the head is carried backward 
and the condyles move forward. In the slight lateral move- 
ments the head is carried towards the shoulder and the condyle 
of that side passes inward, while the one of the opposite side 
passes outward in the corresponding cavity. Motion between 
the atlas and axis is confined to revolution of the atlas around 
the odontoid process of the axis. In this movement, the head 
is turned to one or the other side, the articular facet gliding 
toward that side over the facet on the process, while the in- 
ferior facet of the atlas of the side to which motion is made, 
glides backward on the axis and the opposite facet glides for- 
ward. 
Movements of the Spine as a Whole. The amount of motion 
which may take place between any two contiguous vertebrae 
is but slight, yet the column as a whole enjoys a wide range, 
as well as a great variety of movements. These movements are SYNDESMOLOGY. 
133 
the four angular movements, flexion, bending forward; exten- 
sion, bending backward, and right and left lateral movement. 
In addition to these a considerable amount of rotation, by twist- 
ing of the ligamentous fibres, is permitted. In flexion the body 
bends forward, compressing the anterior fibres of the inter- 
vertebral disks and putting the posterior fibres on the stretch, 
the spine becoming convex backward. This movement is limited 
not only by the compressibility of the disks, but by the tension 
on the posterior fibres, while the supra- and inter-spinous and 
sub-flava ligaments are all stretched. The inferior articular 
processes glide upward on the superior in this movement. 
Flexion and extension are both free in the cervical and lumbar 
regions, the vertical direction of the articular processes limit- 
ing the movement in the dorsal. Lateral flexion is most free in 
the cervical region, the inversion of the superior articular pro- 
cesses limiting it in the lumbar, while the attachment of the 
ribs prevents it in the dorsal, where the shape and direction 
of the articular processes would indicate that it should be most 
free. In this movement the articular process of the side away 
from which motion is made glides upward on the one below, 
the reverse movement taking place on the side flexed. The 
lateral margins of the disks would be compressed and the fibres 
of all ligaments on the opposite side put on the stretch. Rota- 
tion of the column takes place by twisting the fibres of the 
intervertebral disks. It is free in the cervical region, slight 
or imperceptible in the dorsal on account of the ribs, while the 
large size of the superior facets, as compared to the inferior, 
allows some rotation in the lumbar region in spite of the fitting 
in of the superior processes between the inferior. Of course 
in rotation there is a certain amount of gliding of the articular 
processes, the movement being arrested by the stretching of 
the vertical fibres of the disks. 
The Sterno-Clavicular Articulation. 
This is a movable joint of the saddle-shaped variety, or a 
joint by reciprocal reception. It is formed by the saddle-shaped 
articular surface on the inner extremity of the clavicle, which 134 
DESCRIPTIVE ANATOMY. 
is concave from above downward and forward, and convex 
from above downward and backward, and a similar surface 
on the upper angle of the manubrium, aided by a concavity 
on the cartilage of the first rib. The following ligaments bind 
the bones together: 
Capsular. 
Rhomboid, or Costo-Clavicular. 
Interclavicular. 
Inter-articular fibro-cartilage. 
The inter-articular fibro-cartilage (discus-articularis) is at- 
tached by one end to the upper, posterior part of the inner end 
of the clavicle and by the other to the junction of the cartilage 
of the first rib with the articular depression on the lateral 
aspect of the manubrium. It serves the double purpose of hold- 
ing the bones together and at the same time divides the joint 
into two synovial cavities. 
The capsular ligament is a thick band of fibres completely 
surrounding the joint, but thicker at some points than at others. 
Thus it is seen to be much thickened behind and in front where 
it is often described as two ligaments, anterior and posterior 
sterno-clavicular. In front it blends with the tendon of the 
sterno-mastoid muscle, above with the interclavicular ligament, 
while below it is continuous with the Rhomboid. The deepest 
fibres of this ligament pass from the two bones to the inter- 
articular cartilage, and not from bone to bone, while the more 
superficial fibres pass from the margin of the receiving cavity 
on the manubrium and cartilage on the first rib to the margin 
of the articular surface on the clavicle. 
The inter-clavicular ligament is a strong thick band attached 
to the upper and posterior aspect of the clavicle of one side, 
blending with the fibres of the capsule, then passes into the 
interclavicular notch to be attached to the posterior part of the 
upper border of the manubrium, and rises to be attached to the 
inner back part of the opposite clavicle. 
The rhomboid, or costo-clavicular ligament is a set of short 
fibres resembling fibro-cartilage, which extend from the rhom- 
boid impression of the clavicle downward, forward and inward, 
to be attached to the upper face of the cartilage of the first rib. SYNDESMOLOGY. 
135 
There are two synovial membranes, one interposed between 
the cartilage and the manubrium and the other between the 
inner extremity of the clavicle and the cartilage. In some cases 
the cartilage is worn through and the synovial sacs communicate 
with each other, practically forming one sac. 
Arteries and Nerves. The blood supply is mainly from a 
branch of the Internal Mammary. The nerve supply is from 
the branch to the sub-clavius. 
The movements of the joint, which take place in all direc- 
tions, are confined within a narrow range, and are always 
of a gliding character. The cartilage accompanies the clavicle 
in all of its movements except upward. Thus in movement of 
the shoulder backward, the inner end of the clavicle, with the 
inter-articular cartilage, passes forward; in forward move- 
ment of the shoulder, the clavicle passes backward; in upward 
movement of the shoulder, the clavicle passes downward; but in 
downward movement of the shoulder, the clavicle passes up- 
ward, putting the fibres of the cartilage on the stretch and 
limiting the extent of the movement. 
Scapulo-Clavicular Articulation. 
This is a movable joint of the arthrodial variety. The articu- 
lating surfaces are an oval facet on the outer extremity of the 
clavicle and a corresponding facet on the internal border of the 
acromion process of the scapula. It must be observed that the 
clavicle, in its outward course, passes just above the coracoid 
process of the scapula, and, while it does not articulate with it, 
receives a ligament from it. 
The bones are held together by two sets of ligaments, a 
capsular, surrounding the articular surfaces, and a coraco- 
clavicular binding the clavicle to the coracoid process. 
The capsular ligament is a strong, but lax band of fibres, 
surounding the joint and attached to the clavicle and acromion 
beyond the articular facets. Inferiorly these fibres pass as far 
as the coraco-clavicular ligament with which they blend. Above, 
they are strengthened by fibres of the deltoid and trapezius. 136 
DESCRIPTIVE ANATOMY. 
The coraco-clavicular consists of two portions, the conoid and 
the trapezoid. 
The conoid ligament is triangular in form and is attached 
by its apex to the coracoid process close to the supra-scapular 
notch, while its base is inserted into the conoid tubercle and 
posterior border of the clavicle. 
The trapezoid, blended internally with the conoid, has its sur- 
faces looking forward and backward. Below it is attached to 
a ridge on the upper aspect of the coracoid process, while above 
it is attached to the oblique ridge running forward and out- 
ward from the conoid tubercle to the anterior border of the 
clavicle. 
This joint has an inter-articular fibro-cartilage (discus- 
articularis), which, however, is often absent. When this is 
present there are two synovial sacs, otherwise, but one. 
Arteries and Nerves. The joint is supplied by the acromial 
thoracic and supra-scapular arteries and by the circumflex and 
supra-scapular nerves. 
The movements of the joint are confined to a slight gliding 
of the articular surfaces upon one another. Usually the scapula 
is the bone which moves; but, of course, when the scapula is 
fixed, the clavicle may glide upward, downward, backward, or 
forward. 
Ligaments of the Scapula. 
Stretched between different points on the scapula are two 
ligaments, coraco-acromial and transverse. 
The coraco-acromial, thick and triangular, is attached by its 
apex to the tip of the acromion and by its base to the coracoid 
process, serving as a protecting arch for the shoulder joint. 
The transverse ligament passes over the supra-scapular notch, 
from one extremity to the other, converting it into a foramen. 
The Shoulder Joint. 
The shoulder is a joint of the diarthrodial class and enarthro- 
dial or ball and socket variety. The bones entering into its 
formation are the upper extremity of the humerus, with its SYNDESMOLOGY. 
137 
globular head, anatomical neck and two tuberosities; and the 
glenoid cavity of the scapula, supported by its neck and over- 
hung by the coracoid and acromion processes. The ligaments 
of the joint are properly but two, the glenoid (labrum 
glenoidale) and capsular, though some accessory bands of the 
latter are frequently dignified as separate ligaments. The 
glenoid ligament is a band of fibro-cartilage, triangular on 
cross section, which is attached by its base around the margin 
of the glenoid cavity, and serves to deepen, but more especially 
to widen, this cavity. It is connected above with the head of 
the biceps muscle which passes through the joint, and by its 
margin is attached to the capsular ligament. 
The capsular ligament is a strong, but loose sac, completely 
investing the articulation, but not holding the bones in apposi- 
tion with each other. It is simply a bag of which the upper 
end is closed by the glenoid cavity and the lower by the articular 
surface of the humerus. Above, this ligament is attached 
around the margin of the glenoid cavity, extending on the neck 
of the scapula further above than below, and blending with the 
glenoid ligament. Below, it is attached around the anatomical 
neck of the humerus, but is prolonged over the tuberosities, 
between which it is continuous with the transverse band which 
binds the tendon of the biceps in its groove. This is frequently 
called the transverse ligament. Inferiorly it is prolonged over 
the surgical neck of the humerus to a slight extent. The upper 
part is very much thicker than any other portion of the liga- 
ment. One portion, that extending from the base of the coracoid 
process to the greater tuberosity of the humerus, is the portion 
individualized as the coraco-humeral ligament. In the interior 
of the joint there may sometimes be seen a fold in the synovial 
membrane, called the gleno-humeral ligament, extending from 
the upper end of the glenoid cavity, along the inner edge of the 
tendon of the biceps, to the lesser tuberosity. From the inner 
edge of the glenoid cavity to the lower part of the lesser tuber- 
osity, and from the lower part of the cavity to the anatomical 
neck, extend two slight bands also called gleno-humeral. The 
capsule is nearly surrounded by muscles whose tendons, as they 138 
DESCRIPTIVE ANATOMY. 
pass over it, are blended with the ligament and supply the 
greater part of its strength. 
The synovial membrane is extensive. It lines the interior 
of the capsule and is reflected over the margin of the articular 
surfaces, but does not reach the points of greatest pressure. 
A prolongation of the membrane is continued over the tendon 
of the biceps muscle, and the sac usually communicates with a 
bursa beneath the sub-scapularis muscle and frequently with one 
beneath the infra-spinatus. 
The joint is powerfully reinforced and protected, not only by 
the numerous muscles which surround it, but also by a protecting 
arch formed by the acromion and coracoid processes and the cor- 
aco-acromial ligament stretched between them. The muscles are, 
above the supra-spinatus, postero-superiorly the infra-spinatus 
and teres minor, antero-internally the sub-scapularis; while 
above, behind, to the outer side and in front the fibers of the 
deltoid form a cushion over the joint. The first four muscles 
blend, at their insertion, with the capsule. 
Arteries and Nerves. The arterial supply is chiefly from the 
anterior and posterior circumflex, but branches are derived 
from the dorsalis scapulae and supra-scapular arteries. The 
nerves are the supra-scapular and circumflex. 
Movements and mechanism. The length of the capsular liga- 
ment, the shallowness of the receiving cavity and the compara- 
tively large size of the humeral head, permit this joint to enjoy 
a greater variety and extent of movement than any other in 
the body. Like all enarthrodial joints it is capable of the four 
angular movements, their combination, circumduction, and axial 
rotation. In flexion the humerus with the forearm is carried 
forward, the head of the bone spinning in the articular cavity 
around an axis which is drawn from the centre of the greater 
tuberosity, through the centre of the head, to the centre of 
the glenoid cavity. The lower part of the head glides upward 
and forward, while the upper part passes downward and back- 
ward. In extension the reverse movement takes place, with, 
of course, a reversal of the mechanism. In abduction the hu- 
merus is carried away from the mid-line of the body, and the SYNDESMOLOGY. 
139 
hand raised, while the head of the humerus glides downward 
in the glenoid cavity until it presses on the inferior fibres of 
the capsular ligament. When the humerus is carried in abduc- 
tion to a right angle with the body, further movement is ar- 
rested by the impact of the bone against the arch of the acromion, 
further movement in this direction being effected by the gliding 
of the scapula on the thoracic wall. Adduction is the reverse 
of abduction. Adduction is limited by the elbow coming in 
contact with the side and cannot be carried further without 
first flexing the arm. Circumduction is the combination of 
these movements, the head of the humerus assuming the position 
of flexion, abduction, extension and adduction, the arm and 
forearm describing a cone whose apex is at the shoulder joint. 
In rotation the head of the humerus moves around an axis drawn 
from the centre of the head downward through the internal con- 
dyle, the head moving backward in inward and forward in out- 
ward rotation. 
The relation of the long head of the biceps to this joint is 
so peculiar as to demand special mention. Attached to the 
upper margin of the glenoid cavity, where it is blended with 
the glenoid ligament, it passes across the upper outer aspect 
of the joint, pierces its capsular ligament, and is covered by a 
prolongation of the synovial membrane which lines the cavity. 
This tendon, therefore, becomes a powerful agent in retain- 
ing the head of the humerus in apposition with the glenoid 
cavity and thus strengthens the joint on its upper and outer 
aspect. 
Radio-Ulnar Articulation. 
The articulation between the two bones of the forearm forms 
a diarthrodial joint of the trochoid or pivot variety. The bones 
articulate at both the upper and lower extremity, being sepa- 
rated by the interosseous space throughout the shafts. 
The ligaments holding the bones together are found at their 
upper and lower extremities and between their shafts. Above, 
the two bones are held together by one ligament, the orbicular, 
which forms three-fourths of a ring, the other fourth being the 
lesser sigmoid cavity of the ulna. 140 
DESCRIPTIVE ANATOMY. 
The orbicular ligament (ligamentum annulare radii) sur- 
rounds the articular rim of the radius and is attached by its two 
ends to the extremities of the lesser sigmoid cavity. The lower 
fibres are tightly stretched around the neck of the radius, just 
below the head, rendering it very difficult to release that bone 
from its grasp. 
The shafts are connected by two ligaments, the interosseous 
and the oblique. 
The oblique (chorda obliqua) is a narrow band which passes 
downward and outward from the ulna, at the base of the coro- 
noid process, to the radius just below the tuberosity. It is 
often wanting. 
The interosseous membrane (membrana interossei ante- 
brachii) extends from the lower extremities of the bones up- 
ward about two-thirds the length of the shafts, leaving an 
interval above between its upper end and the oblique ligament. 
Its fibres are directed downward and inward between the inner 
border of the radius and the outer border of the ulna. About 
the lower third of the forearm, the membrane is pierced by a 
foramen for the anterior interosseous artery. 
At their lower extremities the bones are held together by 
two ligaments and the triangular fibro-cartilage. 
The two ligaments are an anterior (volar) and a posterior 
passing across the two bones. 
The triangular cartilage (discus articularis) tips the summit 
of the capitulum ulnae; and excludes it from the wrist joint. By 
its apex it is attached to the pit between the styloid process of 
the ulna and the capitulum ulnae; by its base to the narrow 
rough surface separating the carpal and sigmoid cavities of 
the radius. The synovial membrane of the superior radio-ulnar 
articulation is continuous with that of the elbow joint; that of 
the lower lies between the ulna and cartilage, and between the 
ulna and radius. 
The movements are two, and in both the radius alone moves. 
It can move forward, pronation, or backward, supination, and 
in both the hand is carried with it. In these movements of 
rotation, or revolution, the radius rotates around an axis repre- 
sented by an imaginary line drawn from the centre of the head SYNDESMOLOGY. 
141 
of the radius through the centre of the capitulum ulnae; con- 
sequently, in performing pronation the sigmoid cavity of the 
radius moves forward on the articular rim of the capitulum 
ulnae, the reverse occurring in supination, while the head of 
the radius rotates in the lesser sigmoid cavity and orbicular 
ligament. 
The Elbow. 
This is a diarthrodial joint of the ginglymoid variety. The 
bones entering into its formation are the trochlear surface and 
the rounded eminentia capitata on the lower extremity of the 
humerus, and the greater sigmoid cavity of the ulna with the 
cup-shaped upper extremity of the radius. The shape of the 
articular surfaces furnished by the radius and humerus would 
render this joint one of the enarthrodial variety; but the move- 
ments are so restricted by the close ligamentous union between 
the ulna and radius, that the joint presents but three of the 
peculiar movements of the enarthrodial joints-rotation, flexion 
and extension. 
There are, as always, some thin fibres which connect the vari- 
ous parts of the ligamentous bands together, completing the 
capsule around the joint. The ligaments are: 
Anterior. 
Internal lateral. 
Posterior. 
External lateral. 
Capsular. 
The (interior ligament is attached above to the humerus just 
above the coronoid fossa, while below it seizes the lower sur- 
face of the coronoid process and the orbicular ligament. 
The posterior ligament is attached above to the humerus just 
above the olecranon fossa and below to the groove on the upper 
surface of the olecranon, and to the bone immediately behind 
this. It is much thinner and weaker than the anterior. 
The external lateral ligament (ligamentum collaterale radi- 
ale) is attached above to a depression beneath the external con- 
dyle, while its base is attached to the orbicular ligament. 142 
DESCRIPTIVE ANATOMY. 
The internal lateral (ligamentum collaterale ulnare) is at- 
tached to the internal condyle, while below it expands into two 
fasciuli with a triangular interval, filled with thin fibres be- 
tween them. The most anterior, which may be traced to its 
attachment to the front of the internal condyle, is attached 
below to the margin of the great sigmoid cavity on the coronoid 
process. The posterior, attached above to the back of the in- 
ternal condyle, is below attached to that margin of the sigmoid 
cavity furnished by the olecranon process. 
The capsular ligament consists of a few thin fibres lying be- 
tween the anterior and internal, internal and posterior, posterior 
and external and external and anterior ligaments. 
The synovial membrane is extensive. It lines the whole of 
the inner face of the capsule, extending upward and behind to 
the olecranon, and in front to the coronoid fossa; while below 
it covers the interior of the orbicular ligament and furnishes 
the lining for the articulation at the superior radio-ulnar articu- 
lation. 
The muscles which strengthen the joint are in front the bra- 
chialis anticus, behind the triceps and anconeous, externally the 
muscles arising from the external condyle, notably the supinator 
brevis; and internally those which arise from the internal 
condyle. 
Arteries and Nerves. The arterial supply of this joint is de- 
rived from communicating branches between the anastomotica 
magna, the superior profunda and inferior profunda arteries, 
the anterior, posterior, and interosseous recurrent branches of 
the ulna, and from the radial recurrent. The nerve supply is 
derived from the ulna as it passes between the internal condyle 
and the olecranon; the median is said to furnish two filaments 
while the musculo-cutaneous contributes one filament. 
The movements are flexion and extension, to which should be 
added the rotation of the radius when that bone revolves in the 
lesser sigmoid cavity. In flexion the greater sigmoid cavity and 
the cup-shaped articular surface of the radius glide upward on 
the corresponding articular surface of the humerus, the move- 
ment being arrested when the coronoid process impinges upon 
the coronoid fossa. In extension the reverse would occur and SYNDESMOLOGY. 
143 
the movement would be arrested by the impact of the beak of 
the olecranon on the bottom of the olecranon fossa. The move- 
ment of the radius will be described with the radio-ulnar articu- 
lation. 
The Wrist Joint (Radio-Carpal). 
This is a diarthrodial joint of the condyloid variety. The 
receiving cavity, oval, concave both from before backward and 
from side to side, is furnished by the lower extremity of the 
radius, aided by the triangular cartilage which shuts out the 
ulna from participation in the joint. The condyle is provided 
by three of the bones of the first row of the carpus, scaphoid, 
semi-ulnar and cuneiform. The ligaments are: 
Anterior. 
Internal lateral. 
Posterior. 
External lateral. 
All ligaments of this joint blend with the ligaments of the 
carpus and can, with difficulty, be separated from them. 
The anterior ligament (1. radio-carpeum) volare) is attached 
above to the margin of the carpal cavity of the radius and to 
the anterior radio-ulnar ligament, and to the anterior margin of 
the lower end of the ulna, while below it is attached to the 
bones of the first row of the carpus, blending with the anterior 
palmar ligamentous fibres which bind together the first and 
second rows. 
The posterior ligament (1. radio-carpeum dorsale) is, in like 
manner, attached above to the posterior margin of the carpal 
cavity and to the posterior radio-ulnar ligament and below to 
the back of the bones forming the first row of the carpus, 
blending with the dorsal carpal ligaments binding the two rows 
together. 
The external lateral ligament (1. collaterale carpi radiale) is 
attached above to the styloid process of the radius and below to 
the tuberosity of the scaphoid and to the trapezium. 
The internal lateral ligament (1. collaterale carpi ulnare) is 
attached above to the styloid process of the ulna, below to the 
inner side of a cuneiform and unciform, to the latter through 144 
DESCRIPTIVE ANATOMY. 
the medium of the internal lateral ligament of the carpus. Be- 
tween these bands are fibres which convert this ligament into 
a capsule. 
The synovial membrane lines the interior of the ligamentous 
fibres and to a slight extent dips in between the scaphoid and 
semi-ulnar and between the semi-ulnar and cuneiform. There 
are no muscles which directly strengthen the joint. Many ten- 
dons pass over it, but their laxity prevents their adding strength 
except in certain positions of the joint. Thus in flexion, with 
the closed fist, the extensor tendons strengthen it behind, and 
in extension, with the hand open, some strength is given by 
the flexors. The tendon, also, by the tonic contraction of the 
muscles, aid in retaining the bones in apposition. 
Arteries and Nerves. The wrist joint gets its arterial supply 
from the anterior and posterior carpal arches of the radial and 
ulna, the interosseous arteries, anterior and posterior, as well 
as some of the ascending branches of the deep palmar arch, also 
contributing to its supply. 
The ulna and posterior interosseous furnish the nerve supply. 
The movements are those usual in condyloid articulations, 
flexion, extension, abduction, adduction and circumduction. The 
mechanism will be readily understood if it is borne in mind 
that in all movements of condyloid joints the distal extremity 
moves in a direction opposite to that of the condyle. Thus in 
flexion, the hand passes forward on the forearm while the 
condyle moves backward in its receiving cavity, pressing 
against the posterior fibres of the ligament. Exaggerated 
movement as from a fall on the flexed hand would produce dis- 
location. In extension the mechanism is the reverse of flexion. 
In adduction the hand is carried toward the mid-line of the 
body, while the condyle passes outward, the movement being 
limited by the external lateral ligament. In abduction the re- 
verse is true. The combination of these movements makes cir- 
cumduction, which may be either inward or outward. In the 
latter the hand would pass from flexion to abduction, thence 
to extension, then to adduction, and again to flexion. The con- 
dyle passing first backward, then inward, forward, outward and 
so to backward again. SYNDESMOLOGY. 
145 
Articulation of Carpus and Metacarpus. 
The bones of the carpus, which lie in the same row, are held 
together by ligamentous fibres passing across them in front and 
behind, palmar and dorsal ligaments, and by fibres which seize 
the adjoining surface of opposing bones, called interosseous 
ligaments. Between the trapezium and trapezoid there is no 
interosseous ligament. In the same manner the metacarpal 
bones of the four fingers are held together at their bases. The 
two rows of carpal bones are held together by ligamentous 
fibres passing from one to the other in front and behind, palmar 
and dorsal ligaments, and by two lateral ligaments, the external 
passing from the scaphoid to the trapezium, the internal from 
the cuneiform to the unciform. 
The metacarpal bones of the four fingers are held to the 
second row of carpal bones by fibres in front and behind, palmar 
and dorsal ligaments, and in one situation by interosseous fibres 
extending from the adjacent parts of the os magnum and unci- 
form to the bases of the third and fourth metacarpal bones. 
The synovial membrane between the first and second rows 
sends prolongations upward and downward between the indi- 
vidual bones of the two rows, as well as between the proximal 
extremities of the metacarpal bones into the carpo-metacarpal 
articulations. This is not true of the synovial sac between the 
metacarpal bone of the thumb and the trapezium. 
The Trapezio-Metacarpal Joint. 
This articulation belongs to the movable class and saddle- 
shaped variety. It is invested by a capsular ligament, and 
allows the four angular movements and their combination, cir- 
cumduction. 
The Metacarpo-Phalangeal Articulation. 
The knuckle joint, or metacarpo-phalangeal, is of the movable 
class and condyloid variety. The condyle is furnished by the 
head of the metacarpal bone and the receiving cavity by the 146 
DESCRIPTIVE ANATOMY. 
top of the corresponding phalanx, aided by a plate of cartilage 
known as the anterior ligament of the joint. 
The ligaments are two lateral, seizing both bones on their 
lateral aspect just beyond the articular surface. The place of 
a posterior ligament is supplied by the extensor tendons of the 
finger. The anterior is not a ligament in the true sense of 
the word, being only a mass of fibro-cartilaginous material at- 
tached to the front edge of the articulating surface on the 
base of the phalanx, and increasing the receiving cavity. To 
this ligament is attached a band of transverse fibres which 
stretch between the distal ends of the metacarpal bones and 
bind them to one another. 
Inter-Phalangeal Articulations. 
These joints are of the diarthrodial class and the hinge variety, 
the trochlear surface being presented by the head of the proxi- 
mal phalanx and the receiving surface by the base of the distal. 
The ligaments, anterior and two lateral, are attached like 
those of the metacarpo-phalangeal articulations, the extensor 
tendons here, also, taking the place of posterior ligaments. 
Arteries and Nerves. The carpal articulations are supplied 
by the carpal arches and the deep palmar arches. The nerves 
are derived from the ulnar, median and posterior interosseous. 
The fingers are supplied by their respective digital branches 
both for nerves and arteries. 
The movements of the carpal joints are confined to a slight 
gliding of one bone on the other-the same statement apply- 
ing to the carpo-metacarpal joint, except the thumb. Move- 
ment at the metacarpo-phalangeal joint consists of the four 
angular movements and their combination, circumduction. 
Movement is freer at the index and little finger than at the 
other two. Movement at the inter-phalangeal articulation is 
confined to flexion and extension. SYNDESMOLOGY. 
147 
Temporo-Mandibular Articulation. 
This articulation is formed by the condyle of the lower jaw 
and the glenoid cavity of the temporal bone. 
This is a diarthrodial joint of the condyloid variety, and pre- 
sents the following ligaments: 
External lateral. 
Capsular. 
Internal lateral. 
Inter-articular cartilage. 
Stylo-maxillary. 
The inter-articular cartilage is sometimes perforated; when 
this is the case, there is but one synovial sac, otherwise there 
are two, one between the cartilage and the condyle and the 
other between the cartilage and the glenoid cavity. 
The external lateral ligament (ligamentum temporo-mandi- 
bulare) is attached to the zygoma above, from its tubercle for- 
ward, and, passing downward and backward, is attached, below, 
to the outer border of the neck of the condyle. 
The internal lateral ligament (1. spheno-mandibulare) is a 
specialized piece of the deep cervical fascia, attached above 
to the spine of the sphenoid and below to the shelf of bone 
forming the lower margin of the inferior dental foramen. 
The capsular ligament (capsula articularis) consists of fibres 
of varying thickness, attached above around the articular 
margin of the glenoid cavity and below to the neck of the con- 
dyle of the lower jaw. This ligament is slightly thickened 
at its inner part, while the external lateral ligament is merely 
a thickening of the capsule. The capsule is attached through- 
out its circumference to the edge of the inter-articular cartilage. 
The inter-articular fibre-cartilage (discus articularis) is oval 
in outline, thinner at the centre than at the circumference, 
concavo-convex on its upper and concave on its lower surface. 
Its margin is closely attached to the capsular ligament. 
The stylo-mandibular (1. stylo-mandibulare) is, properly, not 
a ligament of this joint. It extends from the styloid process of 148 
DESCRIPTIVE ANATOMY. 
the temporal bone to the angle and posterior border of the ramus 
of the lower jaw. 
Arteries and Nerves. The lower jaw receives its nervous 
supply from the auriculo-temporal and masseteric branches of 
the mandibular. The arterial supply is from the temporal. 
Muscles. The joint is strengthened on the outer side by the 
masseter, internally by the internal pterygoid and above by the 
temporal. 
The movevents are elevation and depression, lateral and for- 
ward movement. In depression the jaw recedes from the upper 
and the condyle, when the movement is not extreme, rolls on 
the inter-articular cartilage around an axis drawn through its 
own centre. When, however, the movement is carried farther, 
both condyle and cartilage roll forward on the eminentia articu- 
laris, exaggerated movement leading to dislocation. 
Elevation is the reverse of depression. 
In lateral movement the jaw is twisted to one or the other 
side, the condyle moving backward in the glenoid cavity on 
the side toward which motion is made, and forward on the 
opposite side. 
In forward movement the two condyles are dragged forward 
on the eminentia articularis, the lower jaw being protruded be- 
yond the upper. 
Costo-Sternal Articulation. 
The ribs have attached to their anterior extremities the costal 
cartilages, which prolong the seven true ribs to the side of the 
sternum, where the cartilages are received into the pits found 
there, and are held in place by ligamentous fibres passing from 
them to the sternum in front and behind. The cartilages of the 
second and third ribs have also each an inter-articular ligament. 
Costo-Vertebral Articulation. 
The parts of the skeleton which enter into a costo-vertebral 
articulation are the posterior extremity of the rib, the body, 
and transverse process of a dorsal vertebra and the inter- 
vertebral disk. SYNDESMOLOGY. 
149 
This articulation is of the diarthrodial class and the arthro- 
dial variety. The ligaments which connect the head of the rib 
with the vertebral column are: 
Anterior costo-vertebral. 
Capsular. 
Inter-articular. 
The anterior costo-vertebral, or stellate (1. capituli cQstae 
radiatum), is attached to the anterior aspect of the head of the 
rib, and radiates in three bundles, the upper of which is attached 
to the body of the vertebra above; the lower to the vertebra 
below, and the middle to the inter-vertebral disk. Owing to the 
divergence of its fibres, this ligament is known as the stellate. 
The arrangement differs from the foregoing description in 
the first, eleventh, and twelfth ribs, where the ligament is at- 
tached to only one vertebra, as the articular facet is furnished 
wholly by one vertebra. 
The capsular ligament (capsular articularis) consists of a 
few scattered fibres around the articulation. 
The inter-articular ligament (1. capituli costae inter-articu- 
lare) is attached to the ridge on the head of the rib and to. 
the inter-vertebral disk, thus dividing the joint into two parts, 
each furnished with a separate synovial sac. For the reason 
above given, the first eleventh and twelfth have no inter-articu- 
lar ligament and but one synovial sac. 
Costo-transverse Articulation. 
The articulation between the ribs and the transverse pro- 
cesses, known as the costo-transverse articulation, presents 
three ligaments-anterior, middle and posterior costo-trans- 
verse. 
The anterior costo-transverse extends from the neck of the 
rib to the transverse process above. 
The middle, or interosseous (1. tuberculi costae), extends 
from the posterior surface of the neck of the rib directly back- 
ward to the front of the transverse process. 150 
DESCRIPTIVE ANATOMY. 
The posterior extends from the tubercle of the rib to the 
apex of the transverse process. 
Movements. The anterior extremities of the ribs are drawn 
upward and downward alternately. When the anterior ex- 
tremity is drawn upward, the head passes downward and the 
rib rotates on an axis extending through the transverse process 
and the tubercle of the rib. The effect of this is to thrust the 
sternum forward, since the anterior is lower than the posterior 
end, and increase the antero-posterior diameter of the thorax. 
At the same time the ribs rotate outward on an axis extending 
from the head to the chondral extremity, increasing the lateral 
diameter of the thorax. As the last rib remains fixed and all 
the others are drawn upward, the vertical measurement of the 
thorax is also increased. 
The Hip Joint. 
The hip JOINT is a diathrodial joint of the enarthrodial 
variety. The bones which enter into its formation are the three- 
quarter-sphere articular surface found on the upper extremity 
of the femur to correspond to the acetabulum, a receiving cavity 
found at the junction of the three bones, the ilium, the ischium, 
and the pubis, which compose the os inominatum. There is at 
the lower, inner portion, at the bottom of the cavity, a non- 
articular roughened surface, which in the articulated skele- 
ton serves partly to form the attachment of the ligament which 
lies in the interior of the joint, and partly serves for the lodg- 
ment of the mass of fat, which prevents jarring of the joint, 
and at the same time lodges the blood vessels which supply the 
joint and prevents pressure upon these vessels. With this ex- 
ception the cavity is articular. 
The ligaments which hold the bones together are: 
Capsular. 
Transverse. 
Cotyloid. 
Teres. 
Some anatomists add other ligaments, which are unimportant 
when considered as separate ligaments, being merely portions SYNDESMOLOGY. 
151 
of the capsular ligament which are developed by the strain upon 
the joint. 
The capsular ligament (capsula articularis), thick and power- 
ful, is attached above to the brim of the acetabulum. As it 
passes around downward and backward, it will be noticed that 
the ligament extends further forward on the acetabulum; that 
is, the extent of its attachment increases as we pass around to 
the posterior aspect of the joint. On reaching the lower portion 
of the joint, this ligament is found to occupy all the space above 
the groove on the ischium. On reaching the upper, inner por- 
tion of the joint it expands considerably, nearly to the ilio- 
pectineal line. As the ligament passes downward it completely 
envelops the joint; and its attachment is again irregular when 
the neck of the femur is reached. Above, the ligament is at- 
tached as far as the digital pit; behind it follows the posterior 
inter-trochanteric line, passes above the trochanter minor and, 
in front, follows the spinal line to the front of the great tro- 
chanter. 
One of the most important of the ligamentary bands compos- 
ing the capsular ligament is the so-called "Y ligament (ilio- 
femoral), which may be seen better in the dry specimen than 
in the recent. The two branches rise by the "tail" or "stem" 
of the Y from just below and just behind the anterior inferior 
spinous process of the ilium; and as they pass downward, 
though there is never any actual interval between them, the 
central fibres are very thin, and the fibres above and below, 
particularly above, are very thick, hence the resemblance to a 
Y. The superior fibres of the Y ligament are attached to the 
upper part of the spiral line and anterior border of the great 
trochanter: the inferior fibres are inserted into the lower part 
of the spiral line just as they reach the inner aspect of the 
bone. 
The others are of comparatively little importance. 
The pubo-capsular ligament is a long, slender band of fibres 
which starts nearly at the pectineal eminence of the pubis; and 
passes downward and outward to blend with the front of the 
capsular ligament. The ischio-capsular band, which comes 
from the tuberosity of the ischium, arises just below the groove; 152 
DESCRIPTIVE ANATOMY. 
and then stretches across, to be inserted near the posterior 
aspect of the base of the trochanter major. These ligamentous 
bands are of comparatively little importance. 
The cotyloid cavity is deepened by a ring of fibro-cartilage, 
the cotyloid ligament (labrum glenoidale). This cartilage is 
nearly triangular on cross section; its base being attached 
around the margin of the acetabulum, its apex, which is free, 
projecting outward. The outer surface is slightly convex, the 
inner, concave, to correspond to the contour of the femoral 
head. That part of the fibro-cartilage which extends between 
the ends of the cotyloid notch is called the transverse ligament. 
It is merely a continuation of the cotyloid ligament, unattached 
at the bottom of the notch, where a space is left for the passage 
of vessels and nerves, the transverse ligament shielding them 
from pressure. 
The ligamentum teres is a band of ligamentous fibres in the 
interior of the joint. It is attached to the margin of the de- 
pression in the bottom of the cavity; its lower fibres are firmly 
attached to the transverse ligament; and at its lower extremity 
it passes into the depression on the head of the femur. 
In this, as in all other movable joints, there is a synovial 
membrane, which here presents one peculiarity. Though the 
ligamentum teres has been spoken of as a ligament, it is not 
a ligament in the true sense of the word. The synovial mem- 
brane starts at the pit on the head of the femur; and passes 
downward, covering all of the head of the femur. Leaving the 
bone itself, it appears on the capsular ligament; continues on 
the cotyloid face until it reaches the cotyloid cavity; then sweeps 
across the mass of fat lying in this cavity; and then passes 
all around the ligamentum teres. The ligamentum teres, there- 
fore, does not enter into the synovial cavity at all, and unless the 
synovial membrane is first cut, neither the ligamentum teres 
nor the mass of fat which lies in the bottom of the depression 
have any communication with the joint. 
Arteries and Nerves. The arteries supplying the joint are 
derived from the obturator, sciatic, internal circumflex and 
gluteal. SYNDESMOLOGY. 
153 
The nerve supply for the joint is drawn from articular 
branches from the sacral plexus, great sciatic, obturator, and a 
filament from the branch of anterior crural supplying the rectus 
muscle. 
The movements of which the hip joint is capable are, of course, 
all of the movements of the enarthrodial joint, viz., flexion, 
extension, adduction, abduction, circumduction, and rotation. 
Any two or more of these movements which are not antagonistic 
with each other may of course, be combined; for instance, there 
may be flexion of the thigh upon the pelvis at the same time 
with adduction, abduction, or axial rotation. 
Flexion, or the movement of the thigh forward, is the most 
extensive of the movements of the joint. In the prepared speci- 
men flexion may be continued until there is almost a complete 
revolution of the joint. The movement consists simply of spinning 
the head in the cavity. The ball spins in the socket on an axis 
drawn from the middle of the trochanter major; through the 
centre of the head to the centre of the acetabular cavity, the 
upper part of the head turning downward and backward and 
the lower part upward and forward. Complete flexion is checked 
by the powerful band of fibres forming the upper limb of the 
Y ligament, though of course in the living man the movement 
is stopped long before this by the contact between the thick 
muscles of the abdomen and the muscles of the thigh. 
Extension, the movement of the thigh backward, is much less 
free than flexion. The movement is hindered by the pectino- 
femoral band in the dead subject; and is also limited, in the 
living man, by the mass of muscles passing in front and behind. 
In abduction and adduction there are complete changes with- 
out rotation. In abduction, which is a movement of the thigh 
away from the mid-line of the body, as the limb is carried out- 
ward, the head of the femur passes downward to the bottom 
of the acetabular cavity, so that it can be felt through the liga- 
mentous fibres. If the movement is carried to excess in the 
living man, splitting of the fibres takes place. 
Adduction is more limited in this than in almost any other 
joint in the body. If the body be in the anatomical position, of 
course the movement is arrested by the limb on the other side; 154 
DESCRIPTIVE ANATOMY. 
if taken in a position of semi-flexion, adduction can never be 
equal to abduction, because it is checked by the powerful su- 
perior fibres of the capsular ligament. The mechanism is the 
reverse of that in abduction, i. e., the head glides upward in the 
acetabular cavity while the thigh approaches, or crosses, its; 
fellow. 
Circumduction is a combination of all the preceding move- 
ments. In this movement the limb passes from flexion to abduc- 
tion, from abduction to extension, from extension to adduction, 
from adduction back to flexion. 
Axial rotation is usually described as the rotation on the line 
which is drawn from the centre of the head of the femur to the 
internal tuberosity of the femur. 
The muscles which strengthen the joint are as follows: 
Above, the rectus and gluteus minimus. In front, the psoas 
magnus and iliacus internus. Internally, the pectineus and ob- 
turator internus. Behind, the outward rotators of the thigh, 
obturators, internus, and externus, pyriformis, the gemelli and 
the quadratus femoris. 
The Knee Joint. 
This is the largest and for many reasons the most important 
joint in the body. By the formation of the bones it is the weak- 
est joint in the body, its strength consisting entirely in the 
powerful bands of ligamentous fibres and the muscles by which 
it is reinforced. It is usually classed as a "hinge joint," being 
the analogue of the elbow; but it is really no more of a hinge 
than the elbow is a pure hinge. In formation it is very complex, 
being a double condyloid joint, combined with a trochlea, and 
possessing three articulations. Its articulations may be ex- 
tended to four, as some of the cartilages which enter into the 
formation of the joint are so arranged as to establish an articu- 
lation between themselves and the bones to which they are at- 
tached. The condyles and their receiving cavities permit all the 
movements belonging to the usual condyloid articulations. 
The bones which compose the knee joint are the two condyles 
of the femur, the two glenoid cavities on the upper extremity 
of the tibia, and the posterior surface of the patella. The liga- SYNDESMOLOGY. 
155 
ments which bind the bones together are divided into two sets: 
the external, or exterior ligaments, and the interior ligaments. 
The exterior ligaments are: 
Anterior. 
Posterior. 
Internal lateral. 
External lateral. 
The anterior ligament, or lig amentum patellae, the most 
powerful of all the bands of ligamentous fibres attached to the 
joint, is nothing more than the tendon of the triceps extensor 
cruris. This muscle passes downward until it reaches the upper 
border of the patella. There the fibres become tendinous, and 
spread out to embrace the patella, passing all around it, some 
being attached to its upper border, others extending so as to run 
down upon its lateral borders, while others run upon its anterior 
surface, the posterior surface being left free. This tendon 
passes downward until it reaches the lower portion of the an- 
terior tubercle, where it is inserted, leaving a little space be- 
tween itself and the upper portion of the tibia. As the liga- 
mentum patellse descends towards its insertion, it does not 
diminish in size; but it gives off from its lateral aspect ten- 
dinous fibres, sometimes spoken of as the lateral patellar liga- 
ments, which pass around until they reach the lateral ligaments 
of the joint; in other words, they form a complete capsule for 
the knee joint. This can be stated of every joint which carries 
a synovial membrane. 
The posterior ligament (L. popliteum obliquum) of the joint, 
one of the most peculiar in the body, is a set of fibres running 
in different directions. In one way or another these are at- 
tached above the condyles of the femur. Some are attached at 
these depressions where the gastrocnemius and the plantaris 
rise; and then extend across the upper margin of the condyloid 
notch. The central fibres extend further up on the shaft of 
the bone; but these, instead of running downward, run up- 
ward and outward. The central fibres of the posterior liga- 
ment spring from the semi-membranosus tendon. These fibres, 
the strongest part of the ligament, spread upward and outward 
from the inner tuberosity of the tibia to be inserted into the 156 
DESCRIPTIVE ANATOMY. 
upper part of the outer condyle of the femur, blending with 
the outer head of the gastrocnemius muscle. 
The internal lateral ligament (1. collaterale tibiale) is at- 
tached above to the inner tuberosity of the femur; passes down- 
ward and is attached to the internal tuberosity, and internal 
face of the shaft, of the tibia. 
The external lateral ligament (1. collaterale fibulare) con- 
sists of two bundles of fibres; and is described as having the 
same attachment below and a different attachment above. It 
is, properly speaking, all one ligament. 
The anterior portion, the long external lateral ligament, is 
attached above to the outer tuberosity of the femur and below 
to the outer part of the head of the fibula. The posterior por- 
tion, or short external lateral ligament, is attached to the outer 
tuberosity of the femur behind and below the preceding liga- 
ment. Below it seizes the styloid process of the fibula. The 
fibres of the two are parallel, the interval between them being 
filled by thin scattered fibres. 
The interior ligaments are: 
Coronary. 
Semi-lunar cartilages. 
Transverse. 
Ligamentum mucosum. 
Crucial, anterior, and posterior. 
Ligamenta alaria. 
The semi-lunar cartilages (menisci), coronary and transverse 
ligaments, do not extend between the femur and tibia; ligamenta 
alaria ligamentum mucosum are folds of synovial membrane; 
the crucial ligaments are interior lateral ligaments and one of 
the most powerful forces binding the bones together. 
The attachment of the semi-lunar cartilages, important from 
both the anatomical and surgical standpoints, are somewhat 
wedge-shaped on cross section. The inferior surface is flat and 
rests upon the tibia; the superior, concave, supports the con- 
dyles of the femur; the base, facing the exterior of the joint, 
is attached to the coronary fibres, while the apex of the wedge 
looks into the interior of the joint. The external is nearly 
circular, being but slightly oval in its outline; the internal, on SYNDESMOLOGY. 
157 
the contrary, is distinctly oval, being longer from before back- 
ward than from side to side. 
The external (meniscus lateralis) is attached just in front of 
the tibia between the spine and the anterior crucial ligament, 
blending with the anterior crucial. Behind, it is attached be- 
tween the spine and the internal cartilage with the crucial liga- 
ment just behind it. 
The internal semi-lunar cartilage (meniscus medialis), which 
is much longer than the external, is attached anteriorly in front 
of the anterior crucial ligament. Behind it is attached between 
the external semi-lunar and the posterior crucial ligament. The 
cartilage can be raised up in any direction, but is attached to 
the bone by the fibres of the capsular ligament of the joint. 
In truth it is not really attached to the bone, except just in 
front and just behind the anterior spine of the tibia. On the 
contrary, all of the fibres which enter into the formation of the 
ligaments of this joint, with the exception of those composing 
the ligamentum patellae, become attached to the edges of the 
semi-lunar cartilages; and from those edges they pass down as 
short fibres to seek their insertion in the tibia. They bind the 
cartilages in position, but leave them so as to be movable. These 
fibres form the coronary ligament. 
The anterior crucial ligament takes its origin from a point 
just in front of the spine of the tibia, where it blends with the 
external semi-lunar cartilage. From that origin it passes up- 
ward, outward, and backward; and is inserted into the internal 
face of the external condyle of the femur. 
The posterior crucial ligament arises from behind the spine 
of the tibia, the posterior extremity of the external semi-lunar 
separating it from the spine. From that origin the direction 
of its fibres is upward, forward and outward, to the external 
face of the internal condyle. The two crucial ligaments cross 
each other in the joint. When they come in contact with each 
other, the posterior crucial ligaments give off a slip of fibres 
which decussates with the anterior crucial ligament. 
The ligamentum mucosum, the patella fold of the synovial 
membrane, is found attached to the front of the inter-condyloid 
notch, and passes from that point, lying between the patella 158 
DESCRIPTIVE ANATOMY. 
and the inter-condyloid notch of the femur, to become attached 
to the lower extremity of the patella. From the lateral edges 
of the ligamentum mucosum are sent off the fringe-like folds 
with masses of fat, spoken of as the ligamenta alaria. 
The synovial membrane is the largest in the body. Above the 
joint a large bursa is formed beneath the triceps, which com- 
municates with the synovial cavity. The membrane passes 
around the condyles from behind to the upper limit of their 
articular surfaces, thence over the back of the patella to the 
ligamentum patellae; thence over the semi-lunar cartilages to 
wind around their edges, line them on both surfaces and cover 
the glenoid cavities on the tibia; thence to the posterior liga- 
ment to mount up to the condyles from which the tracing was 
started. The crucial ligaments are surrounded by the synovial 
membrane, and, while in the knee-joint, are not in the synovial 
cavity. This large serous cavity is partially subdivided by the 
ligamentum mucosum and the ligamenta alaria. 
The external cartilage, just before it reaches its attachment, 
extends its transverse band across to become attached to the 
internal cartilage, thus forming the transverse ligament of the 
joint. 
Between the ligamentum patellae and the upper part of the 
anterior tubercle of the tibia, there is a little sack, which does 
not communicate with the joint, but forms a bursa, so as to 
have a freely gliding tendon over the upper extremity of the 
tibia. At the back of the joint, beneath the two heads of the 
gastrocnemius muscle, are found two more bursae; beneath the 
tendon of the popliteus is found another. These frequently 
communicate with the joint, hence they are known as the 
synovial bursae. Between the skin and the front of the patella 
is another bursa, which can be easily found in the healthy man 
and which does not communicate with the joint. It is a mucous 
bursa. 
Movements. This joint never makes the movement of a pure 
"hinge joint." If placed in a position of extreme flexion, the 
posterior portion of the condyles rests upon the posterior part 
of the semi-lunar cartilages. Place the knee in a position of 
half-flexion, and the central portion of the condyle then rests SYNDESMOLOGY. 
159 
upon the central portion of the cartilages, the axis having 
changed so that the tibia has been carried forward about half 
an inch. Bring the leg further forward, and the axis of rota- 
tion will have been brought further forward. During both 
flexion and extension there is a certain degree of rotation caused 
by the prolongation of the internal condyle. In extreme ex- 
tension the femur and tibia are nearly parallel; but in extreme 
flexion the tibia rotates outward, the heel points to the oppo- 
site side and the line of the tibia obliquely crosses that of the 
femur. 
In addition to the movement between the femur and the tibia, 
there is slight rotation inward or outward between the semi- 
lunar cartilages and the tibia. Besides these, there is a con- 
stant movement of the patella on the femur. When the limb 
is in extreme flexion, only the upper portion of the patella is in 
contact with the femur; when drawn up the central, or bulged 
portion, is in contact with the femur; and in extreme extension, 
the lower portion is in contact with the femur. There is a 
line extending from the centre of the patella vertically and 
another transversely; and some say there is a third line, which 
completes the division of the patella into six separate compart- 
ments. 
The muscles which strengthen the articulation are, primarily, 
the triceps extensor cruris; behind, the two heads of the gas- 
trocnemius and the plantaris; on the outer side, the tendon 
of the biceps flexor cruris; and on the inner side, the semi- 
tendinosus, which is in reality the only one that strengthens 
the joint internally. The popliteus powerfully strengthens the 
joint upon its outer side; and it is a powerful strengthening 
agent on its posterior aspect. 
Arteries and Nerves. The arterial supply of the joint is fur- 
nished by articular branches from the popliteal, by the anterior 
and posterior recurrent branches of the anterior tibial, by the 
anastomotica magna branch of the femoral and by the descend- 
ing branches from the external circumflex. 
The nerve supply is derived from the external and internal 
popliteal, the obturator and from the anterior crural. 160 
DESCRIPTIVE ANATOMY. 
The Tibio-Fibular Articulation. 
The upper and lower extremities of these bones are held 
together by ligamentous fibres, while there is a strong interos- 
seous membrane extended between their shafts. 
The superior tibio-fibular joint is of the arthrodial variety 
and the bones are held together by anterior and posterior liga- 
mentous fibres, passing directly between the contiguous sur- 
faces of the two bones. They are united by a few scattered 
fibres to protect the synovial membrane, forming an imperfect 
capsule. 
The inferior tibio-fibular joint (syndesmosis tibio-fibularis) is 
an articulation of the amphiarthrodial class. A rough surface 
is presented by each of the bones for the reception of the power- 
ful interosseous ligament which passes between them. There 
are also anterior and posterior fibres passing from one bone to 
the other, forming the anterior and posterior inferior tibio- 
fibular ligaments. The lower part of each bone presents a small 
smooth surface, coated with cartilage in the recent state whose 
synovial membrane communicates with the ankle joint. Slightly 
in front of the posterior ligament is a transverse band extend- 
ing inward to the posterior edge of the tarsal cavity of the tibia. 
The interosseous membrane is composed of oblique fibres 
directed downward and outward and extending from just below 
the knee to within a short distance of the ankle. These fibres 
are attached to the interosseous ridges on the two bones. Above 
the membrane is seen an oval aperture for the transmission of 
the anterior tibial vessels. At its lower portion the membrane 
is perforated for the passage of the anterior peroneal artery. 
Movements. A slight gliding movement only is permitted 
between the two bones above, while below there is practically 
no movement, the little permitted being confined to a slight twist- 
ing of the fibres of the interosseous ligament. 
The Ankle Joint (Talocrural). 
This joint belongs to the movable class and hinge or, more 
correctly, the mortise and tenon variety. Its articular surfaces SYNDESMOLOGY. 
161 
are contributed by the lower extremities of the tibia and fibula, 
above, and the upper and lateral surfaces of the astragalus below. 
The ligaments are: 
Anterior. 
Posterior. 
Internal lateral, or deltoid. 
External lateral. 
The anterior, thin and fatty, is attached above to the front 
of the tibia just above its articular surface and below to the 
upper surface of the neck of the astragalus. 
The posterior, more insignificant than the anterior, is mainly 
for the protection of the synovial membrane. It consists of a 
few scattered fibres attached above to the tibia and below to the 
os calcis. 
The internal lateral or deltoid ligament (1. deltoideum), is a 
dense and powerful mass of fibres which embraces the tip of 
the internal malleolus by its apex and by its broad base is at- 
tached to the tuberosity of the scaphoid, to the inner face of the 
astragalus, below the articular facet, and to the os calcis, where 
it also serves to bind the astragalus and the os calcis together. 
On section this ligament is seen to consist of two layers. 
The external lateral ligament, usually described as one, is 
really three separate ligaments. The anterior fasciculus (an- 
terior talo-fibular), the weakest, is attached above to the anterior 
border of the external malleolus and passing downward and 
forward reaches the upper, outer aspect of the astragalus. The 
middle (calcaneo-fibular), passes from the tip of the malleolus 
vertically downward to the tubercle on the outer face of the os 
calcis. The posterior (posterior talo-fibular) is attached ex- 
ternally to a deep .depression on the inner face of the malleolus 
and passes horizontally inward to seize the outer face of the 
astragalus behind its articular facet. 
The synovial membrane is extensive and lines the inner face 
of the ligaments as well as the bones. 
Muscles. The joint is strengthened behind by the tendon 
Achilles, which takes the place of a posterior ligament. Antero- 
internally is the tibialis anticus, postero-internally the tibialis 
posticus while externally are the two peroneal tendons. The 162 
DESCRIPTIVE ANATOMY. 
flexor and extensor tendons are too lax to add any strength to 
the joint. 
Arteries and Nerves. The malleolar arteries supply the joint 
with blood while the anterior and posterior tibials give it its 
nervous supply. 
The movements are flexion and extension, although in one 
position a slight degree of lateral movement is permitted. In 
flexion the foot is drawn up toward the leg, the articular surface 
of the astragalus moving slightly backward in the receiving 
cavity. Extension is the reverse of flexion. In forced extension 
the narrow part of the astragalus is brought forward into the 
broadest part of the receiving cavity, and in this position a slight 
degree of lateral movement is permitted. 
The Articulations of the Tarsus. 
The articulations of the tarsus consist of the articulation be- 
tween the bones of each row and the union of the two rows. 
Calcaneo-Astragaloid Articulation. 
Articulatio Talo-Calcaneo. 
The two bones of the first row of the tarsus are held together 
by three ligaments, external, posterior and interosseous. 
The external calcaneo-astragaloid ligament (1. talo-calca- 
neum laterale) extends from the outer side of the astragalus, 
just behind and internal and as far as the anterior fasciculus 
of the external lateral of the ankle, to the outer face of the 
os calcis. It lies between the anterior and middle fasciculi of 
the external lateral of the ankle. 
The internal calcaneo-astragaloid (1. talo-calcaneum medi- 
ale) connects internal tubercle of the astragalus with the back 
of the sustentaculum. 
The posterior calcaneo-astragaloid (1. talo-calcaneum pos- 
terius) passes from the posterior extremity of the astragalus 
to the contiguous upper aspect of the os calcis, and is but a SYNDESMOLOGY. 
163 
continuation of the protecting fibres, called the posterior liga- 
ment of the ankle. 
The interosseous (1. talo-calcaneum interosseum) is by far 
the most important bond of union between the two bones. It 
consists of a large number of fibres, filling the sinus tarsi, and 
passing directly and obliquely between the surfaces which form 
that canal. 
The Articulation Between the Bones of the Second Row. 
The bones of the second row are held together by fibres pass- 
ing across the dorsal and plantar faces and by interosseous 
fibres between opposing surfaces. 
The Articulation Between the Two Rows. 
The two rows of the tarsus are held together by three sets 
of ligaments, two sets passing from the os calcis to the cuboid 
and scaphoid, though the latter does not articulate with it, and 
one set passing between the astragalus and scaphoid. 
Calcaneo-Cuboid Articulation. 
The ligaments binding the os calcis to the cuboid are four, 
two dorsal and two plantar. 
The superior calcaneo-cuboid is thin and narrow and passes 
between the contiguous surfaces of the bones on the dorsum of 
the foot. 
The internal calcaneo-cuboid, or interosseous, is a thick short 
band of fibres springing from the depression between the os 
calcis and the astragalus and inserted into the inner side of the 
cuboid. At its origin it is closely blended with the superior 
calcaneo-scaphoid. 
The long inferior calcaneo-cuboid ligament (1. plantare lang- 
um) is attached behind to the inferior surface of the os calcis 
from its posterior to its anterior tubercle; and in front to the 
peroneal ridge on the under surface of the cuboid and to the bases 
of the metatarsal bones of the second, third and fourth toes. It is DESCRIPTIVE ANATOMY. 
164 
much thicker and stronger, as well as longer, than the short 
inferior calcaneo-cuboid, which lies immediately above it. 
The short inferior calcaneo-cuboid ligament (1. calcaneo- 
cuboidum plantare) is about one inch in length. It is attached 
to the anterior tubercle of the os calcis and to the bone in front 
of it as far as the margin of the articular surface; and, by 
its anterior extremity, to the under surface of the cuboid behind 
the peroneal ridge. 
Calcaneo-Scaphoid Ligaments. 
Connecting the os calcis and scaphoid are two ligaments, 
superior and inferior calcaneo-scaphoid. 
The superior, one arm of the Y ligament, the other arm being 
furnished by the internal calcaneo-cuboid, passes forward and 
inward from the front upper part of the os calcis to the scaphoid. 
The inferior calcanea scaphoid is much stronger than the 
superior, and passes from the inner front aspect of the os calcis, 
beneath the head of the astragalus, to the lower surface of the 
scaphoid. 
The Astragalo-Scaphoid Articulation. 
The only ligament connecting the astragalus and the scaphoid 
is the superior astragalo-scaphoid which is thin and weak and 
passes from the neck of the astragalus to the upper surface of 
the scaphoid. 
The Tarso-Metatarsal Articulation. 
The first metatarsal bone articulates with the internal cunei- 
form; the second, with the middle cuneiform, by its base, and 
laterally with the internal and external cuneiform bones, being 
jammed between these and extending farther back than the 
other metatarsal bones; the third articulates with the external 
cuneiform, and the fourth and fifth with the cuboid. 
The tarsus is held to the metatarsal by dorsal and plantar 
ligamentous fibres and by three interosseous ligaments-one 
from the internal cueniform to the second metatarsal and one 
from the external cueniform to the third metatarsal. THE VISCERA. 
165 
The metatar so-phalangeal, the inter-phalangeal and the "in- 
ter-metatarsal" are exactly similar to those of the hand. 
THE VISCERA. 
The Alimentary Canal and Appendages. 
The alimentary canal begins at the mouth and ends at the 
anus, the intermediate portions being found in the neck, thorax 
and abdomen. In the neck are the fauces, pharynx and part of 
the oesophagus; in the thorax is the remaining portion of the 
oesophagus, while the rest of the canal is found in the abdomen. 
The Mouth. 
The mouth begins at the lips and terminates behind in a 
short constricted portion called the fauces. It is bounded above 
by the hard palate, below by the tongue, and on each side by the 
cheeks. 
The lips are two, upper and lower, separated by the transverse 
labial fissure. Each is formed chiefly by its segment of the 
orbicularis oris muscle, covered externally by skin and internally 
by mucous membrane, a concentric fold of which, called froenum 
labii, extends in the middle line from each lip to the gum behind. 
The vestibule is the space between the lips and teeth; the 
cavity of the mouth proper extends from the teeth to the fauces. 
The cheek consists chiefly of the buccinator muscle, covered 
externally by skin and internally by mucous membrane, which 
is reflected from it to the gum and presents, opposite to the 
second molar tooth of the upper jaw, the opening, on a papilla, 
of Stenson's duct from the parotid gland. 
The hard palate is formed anteriorly by the meeting in the 
middle line of the palate processes of the superior maxillary, 
and posteriorly by the horizontal plate from each palate bone. 
It is bounded in front and at either side by the alveolar process 
of the superior maxillary bones, containing the teeth of the 
upper jaw. It is covered by mucous membrane both above and 
below, forming the floor of the nasal fossae above and the roof DESCRIPTIVE ANATOMY. 
166 
of the mouth, below; on the lateral aspect the mucous membrane 
is roughened by glands, called palatal, and is continued on the 
gums. 
The floor of the mouth is formed by the anterior two-thirds 
of the tongue, the posterior third of the tongue forming the floor 
of the fauces, and, below that, entering into the formation of 
the anterior wall of the pharynx. Below the tongue is held in 
place by the froenum linguae, on each side of which the openings 
of Wharton's ducts are seen. 
The tongue is flattened from above downward, is conical in 
shape and curved in direction, being convex above antero-pos- 
teriorly, and extends from the hyoid bone behind to the incisor 
teeth in front, its base being adherent to the hyoid bone and 
its apex free and anterior. 
The mucous membrane, covering the dorsum of the tongue, 
passes around the sides and tip, thus enveloping most of the 
organ, and leaves the lower surface to become continuous with 
the membrane lining the gum of the lower jaw. In contact with 
the posterior part of the dorsum is the front of the epiglottis, 
which is held to it by three folds of mucous membrane, the 
glosso-epiglottic ligaments, middle and two lateral. 
The mucous membrane covering the tongue and mouth is con- 
tinued back through the fauces to blend with that which lines 
the gullet. 
The Fauces. 
The fauces, or isthmus of the fauces, is that narrow part 
of the alimentary canal which connects the mouth posteriorly 
with the front of the pharynx. It is about one and one-half 
inches long, about the same in width, and rather less in depth; 
the size, however, varying greatly, for its walls are chiefly 
formed of muscular tissue, which is peculiarly subject to reflex 
action. 
The roof of the fauces is the soft palate; the floor is a part 
of the dorsum of the tongue; the sides are formed by two arch- 
ing muscles, and, between them, the tonsil. The muscle in 
front is the palato-glossus, forming the anterior pillar of the 
fauces (arcus glosso-palatini) ; that behind is the palato-pharyn- THE VISCERA. 
167 
geus, forming the posterior pillar of the fauces (arcus pharyn- 
go-palatini). The wall, in every aspect, is covered by mucous 
membrane. 
The soft palate, or velum pendulum palati, is thin and flattened 
from above downward and forward. It is attached above to 
the posterior border of the hard palate and hangs downward 
and backward, separating the fauces from the upper part of the 
pharynx. It is prolonged, in the middle line below, by a nipple- 
like projection, some half an inch long, called the uvula. 
Pharynx. 
Food, in order to reach the stomach, passes through four 
successive portions of the alimentary canal. The first two of 
these have been described, viz.: the mouth and fauces. Leav- 
ing the latter, food enters the pharynx, whence it passes to the 
oesophagus, in which the pharynx terminates, and the oesophagus 
conveys it to the stomach. 
The pharynx is an oblong tube situated behind the larynx 
and extending from the lower face of the basilar process of the 
occipital bone to the fifth cervical vertebra where it terminates 
in the oesophagus. By the lower margin of the soft palate it 
is divided into an upper portion, establishing communication 
between the nasal cavities and the larynx below, and the same 
cavities and the middle ear on the side, through the Eustachian 
tube; and a lower portion receiving the opening of the fauces 
above and opening into the oesophagus below. By its musculo- 
aponeurotic fibres it is attached to all the surrounding firm 
structures, base of the occipital bone, pterygoid processes of the 
sphenoid, base of the tongue, hyoid bone, inferior maxilla and 
the larynx. From the occipital down to the attachment to the 
cartilages of the larynx it is a large cavity always held open 
by its attachment to the firm surrounding structures; but from 
the larynx to its termination, the anterior and posterior walls 
are more or less closely in contact, except during the act of 
swallowing. The muscular wall is deficient above and behind, 
where a concave space is seen on either side above the superior 
constrictor; here the pharyngeal aponeurosis is thicker than 168 
DESCRIPTIVE ANATOMY. 
elsewhere. In the anterior wall, above the soft palate, the open- 
ings of the posterior nares are seen on either side; while further 
back and opposite the posterior extremity of the inferior tur- 
binated bones, may be seen the openings of the Eustachian 
tubes. Below the soft palate the opening for the fauces occupies 
the whole breadth of the anterior wall, while below this is the 
antero-posterior opening of the larynx, behind which is the 
transverse, slit-like opening into the oesophagus. The pharynx 
is separated from the front of the bodies of the upper five cer- 
vical vertebrae by a layer of the deep cervical fascia and some 
loose connective tissue. It is about four and one-half inches in 
length and tapers as it descends. 
Structure. 
The alimentary canal throughout is made up of an internal 
mucous coat, resting upon a thin fibrous layer which is in turn 
supported by muscular fibres. In the tongue, soft palate and 
pharynx the muscular coat makes up the bulk of the organ, but 
the arrangement differs in each, and will now be described. 
Tongue. 
The tongue consists of two sets of fibres, called intrinsic and 
extrinsic muscles of the tongue. The extrinsic muscular fibres 
seek points of attachment to surrounding hard parts, their 
lingual extremities then passing into the tongue to blend with 
the intrinsic muscles found there. These muscles are the fol- 
lowing : 
Extrinsic. 
Stylo-Glossus. 
Hyo-Glossus. 
Palato-Glossus. 
Genio-Hyo-Glossus. 
Intrinsic. 
Superior Lingualis. 
Inferior Lingualis. 
Vertical Lingualis. 
Transverse Lingualis. THE VISCERA. 
169 
Stylo-Glossus. 
The STYLO-GLOSSUS arises from the anterior and outer side 
of the styloid process of the temporal bone near its apex, and 
from the stylo-maxillary ligament, and passing downward, for- 
ward and slightly inward is inserted into the side of the tongue, 
its fibres running as far as the tip where they meet with the 
muscle of the opposite side. The fibres of this muscle blend 
with those of the superior and inferior lingualis. 
Hyo-Glossus. 
The hyo-GLOSSUS is a flat quadrilateral muscle which arises 
from the side of the body and both cornua of the hyoid bone, 
passes directly upward and is inserted into the whole length 
of the tongue, to the inner side of the stylo-glossus, its fibres 
blending with the vertical lingualis. 
Palato-Glossus. 
The palato-glossus is a small muscle found occupying the 
anterior fold of the fauces. Arising in the soft palate it passes 
downward and inward and is inserted into the side of the tongue, 
its fibres blending with the transverse lingualis. 
Genio-Hyo-Glossus. 
The GENIO-HYO-GLOSSUS is a thin, radiated, fan-shaped muscle 
found lying close beside its fellow near the mid-line and extend- 
ing from base to apex of the tongue. It arises by its apex from 
the superior genial tubercles and is inserted into the whole 
length of the tongue, some of its posterior fibres being attached 
to the body of the hyoid bone. Its fibres blend with the vertical 
lingualis, running between the fibres of the longitudinal and 
transverse lingualis. 
These muscles, except the palato-glossus, are supplied by the 
hypo-glossal nerve. The palato-glossus is supplied by branches 170 
DESCRIPTIVE ANATOMY. 
from the pharyngeal plexus. The lingual artery is the chief 
source of the blood. 
The tongue is divided by a vertical fibrous septum which 
occupies the middle line and receives the insertion of the trans- 
verse lingualis muscle. The intrinsic fibres, largely derived from 
the extrinsic, are two superficial sets, superior and inferior, 
which extend from base to apex of the organ, and a transverse 
and vertical set, the one running from the upper to the lower 
surface and the other from the septum to the lateral edges. 
These latter fibres are mingled with each other so as to form a 
muscular net work extending throughout the tongue. 
Action. The intrinsic muscles can act only to produce changes 
in the shape of the tongue, while the extrinsic not only change 
the shape, but the position as well. The stylo-glossus can draw 
the tongue upward and backward, or, if one muscle alone acts, 
upward, backward and toward the side of the muscle acting. 
The hyo-glossus draws the tongue downward and backward, 
increasing the size of the fauces and aiding the intrinsic fibres 
in shortening the organ. The palato-glossus widens the tongue 
and elevates its base, depresses the soft palate and constricts 
the fauces while the genio-hyo-glossus draws the tongue forward 
by its posterior fibres, shortens it by the approximation of pos- 
terior and anterior, while the central fibres depress the organ 
and make the dorsal face concave. The lower fibres can draw 
the hyoid bone upward and forward. 
Muscles of the Soft Palate. 
Levator Palati. 
Tensor Palati. 
Azygos Uvulae. 
Palato-Glossus. 
Palato-Pharyngeus. 
The palato-glossus was described with the muscles of the 
tongue. THE VISCERA. 
171 
Levator Palati. 
The levator palati arises from the rough surface on the 
basilar face of the petrous bone, near its apex, and from the 
cartilaginous portion of the Eustachian tube, and descends to 
be lost in the soft palate. Its name indicates its action. 
Tensor Palati. 
The tensor palati is a small muscle which forms a right 
angle on itself, hence its synoym of circumflexus. It arises 
from the scaphoid fossa of the pterygoid process, from the 
spinous process of the sphenoid bone and from the cartilaginous 
portion of the Eustachian tube, and first descending vertically, 
then turning transversely inward around the hamular process 
of the pterygoid, it spreads out into a broad aponeurosis in 
the soft palate. Its action is indicated by its name. 
Azygos Uvulae. 
From the posterior termination of the soft palate there hangs 
pendulous, in the centre, a short, conical mass called the uvula, 
which, when dissected, is found to consist, exteriorly, of mucous 
membrane, and, interiorly, of a pair of minute muscles, each 
of which, arising from the palatal spine, descends beside its 
fellow and is lost in the mucous membrane of the uvula. These 
two muscles were formerly considered as one, hence their name. 
It is their presence in the uvula which accounts for its constant 
and varied movement. 
Palato-Pharyngeus. 
The palato-pharyngeus arises in the soft palate and passes 
downward and backward to enter the wall of the pharynx, 
where some of its fibres are lost, the rest being inserted into 
the posterior border of the thyroid cartilage. Its action is the 
same as the preceding muscle and its synonym is constrictor 
isthmi faucium posterior. 172 
DESCRIPTIVE ANATOMY. 
The Muscles of the Pharynx. 
The pharynx is lined by mucous membrane, resting on a thin 
fibrous coat. External to the mucous coat is a muscular coat 
consisting, like that of the intestines, of circular and longi- 
tudinal fibres, but differing in that the muscular fibres are here 
red and not pale, and are gathered into bundles which are de- 
scribed as separate muscles. The circular fibres are arranged 
in flattened bundles on each side, each bundle intersecting its 
fellow of the opposite side on the middle of the back of the 
pharynx where they form a raphe. Each pair of bundles overlap 
the lower edge of the pair above. When traced from the raphe 
forward it is seen that these fibres do not encircle the entire 
pharynx but pass from its sides to seek firm neighboring points 
of attachment, from which to exert traction, thus leaving the 
front of the pharynx devoid of muscular fibres, this part of its 
wall being formed by mucous membrane alone. The larynx 
resting on the front of the pharynx, is in contact with the 
mucous membrane and is embraced by these circular fibres. 
These muscles, from their action, are known as the constrictors 
of the pharynx; and as there are three separate bundles, they 
are described as superior, middle and inferior constrictors. The 
direction of their fibres is not horizontally backward, but back- 
ward and upward. 
Inferior Constrictor. 
The inferior constrictor arises from the oblique line on 
the ala of the thyroid cartilage and surface behind it, from the 
side of the cricoid cartilage and from the upper two rings of 
the trachea. It runs backward and upward, its upper fibres 
passing obliquely upward, overlapping the middle constrictor, 
and is inserted into the raphe of the pharynx. 
Middle Constrictor. 
The middle constrictor arises from the upper border and 
both cornua of the hyoid bone, and from the stylo-hyoid liga- THE VISCERA. 
173 
ment, a fibrous cord extending from the hyoid bone to the sty- 
loid process. The fibres radiate somewhat, spreading out on 
the side of the pharynx, and are inserted into the raphe. The 
inferior fibres are overlapped by the inferior constrictor, and 
the superior fibres overlap the superior constrictor. So great 
is this overlapping that when viewed from behind but little 
of the superior constrictor can be seen, the raphe of the middle 
constrictor extending to the basilar process. 
Superior Constrictor. 
The superior constrictor lies just beneath the skull and is 
overlapped by the middle. It arises from the lower half of the 
internal pterygoid plate, from its hamular process, from the 
pterygoid-maxillary ligament, from the extremity of the molar 
ridge of the lower jaw, and by a few fibres from the side of 
the tongue. It passes backward and is inserted into the raphe, 
which is attached to the basilar process. The upper edge of 
this muscle presents a concave border, thus leaving an arched 
interval between it and the skull above, over which the fibrous 
tissue beneath the mucous membrane of the pharynx extends, 
and is here so much thickened as to form a strong fibrous mem- 
brane. 
The longitudinal fibres of the pha'rynx are, like the circular, 
gathered into bundles, of which there are two pairs. These 
are described as distinct muscles arising from points above the 
pharynx and inserted into it. One of them, the palato-pharyn- 
geus, has been described as a part of the soft palate; the other 
is known as the stylo-pharyngeus. 
Stylo-Pharyngeus. 
The stylo-pharyngeus arises from the inner side of the 
base of the styloid process and descends to the side of the 
pharynx, entering its wall between the superior and middle con- 
strictors. Some of the fibres are lost in the pharynx, while 
some are continued to the posterior border of the thyroid car- 
tilage. Action-it elevates and widens the pharynx. 174 
DESCRIPTIVE ANATOMY. 
(Esophagus. 
The (ESOPHAGUS continues the course of the alimentary canal 
from the termination of the pharynx, at the commencement 
of the trachea on the front of the body of the fifth cervical ver- 
tebra, down the front of the vertebral column, through the neck 
and thorax, piercing the diaphragm at the oesophageal opening, 
opposite the tenth dorsal vertebra, and terminating at the car- 
diac orifice of the stomach. It is about nine inches long. 
In structure the oesophagus resembles the pharynx, but its 
muscular coat is pale, not red, and is not arranged in distinct 
bundles. It is the narrowest part of the alimentary canal, but 
the most muscular. 
Relations of the Pharynx. 
In adition to the structures mentioned as opening into or 
being connected with the pharynx, it has important relations 
to structures on the side of the neck. Thus on either side are 
the muscles attached to the styloid process of the temporal and 
internal to these the internal jugular vein and internal carotid 
artery; and, between these two, the ninth, tenth and twelfth 
nerves, with the sympathetic behind. Below the parotid gland 
the external carotid artery becomes an external relation, while 
the lingual lies on the middle constrictor. Below the upper 
border of the thyroid cartilage the common carotid becomes an 
external relation. 
Relations of the (Esophagus. 
The relations of the (esophagus must be studied in the neck 
and in the thorax. The gullet is about nine or ten inches in 
length, extending from the disk between the fifth and sixth 
cervical vertebrae to the front of the body of the tenth dorsal. 
It is not a straight tube but presents antero-posterior curves 
corresponding to the curvatures of the spinal column. There 
are also three lateral deviations-two to the left and one to 
the right. At its commencement it lies on the middle line of 
the body, but curves to the left until it reaches the root of the THE VISCERA. 
175 
neck. From this point it curves to the right until it again 
reaches the middle line, opposite the fifth dorsal vertebra, and 
from there passes steadily to the left again until it terminates 
opposite the body of the tenth dorsal vertebra. 
In the neck and upper part of the thorax the oesophagus is 
separated from the front of the vertebral column by a layer of 
fascia and by the longus colli muscles, particularly the muscle 
of the left side. In the lower part of the thoracic portion it is 
more widely separated from the vertebrae. The trachea lies in 
front of the oesophagus which is thus shut off from contact with 
the thyroid gland, except that the left lobe of the latter touches 
the oesophagus on the left side. The left and right common 
carotid arteries are lateral relations, the left being nearer than 
the right. At the root of the neck the thoracic duct is a left 
and slightly posterior relation while the left recurrent laryngeal 
nerve lies in the groove between the trachea and oesophagus. 
In the thorax the oesophagus first lies behind the lower part 
of the trachea, which separates it from the transverse aorta, 
and then behind the bifurcation of the trachea and the left 
bronchus. Below the trachea the pericardium lies on the front 
of the oesophagus to its termination. Laterally the gullet is 
in contact with the two pleurae, although the left is a relation 
for a greater distance than the right. To the right, in the 
upper part, and separated from it by the trachea, is the in- 
nominate artery, and below this, the vena azygos major is for 
a moment to the right side. On the left is the left common 
carotid artery, while the left sub-clavian is a more distant rela- 
tion. The descending aorta becomes a left relation at the lower 
border of the fourth dorsal vertebra and remains a left relation 
to the upper border of the seventh dorsal, below which point 
the aorta is behind and finally behind and to the right. Behind 
is the longus colli muscle above, and in front is the recurrent 
laryngeal nerve of the left side from the transverse aorta up- 
ward. The thoracic duct is a posterior relation throughout the 
thoracic portion, but, below the transverse aorta, lies in the 
interval between the aorta and the oesophagus. The vena azygos 
major is a posterior relation, while the azygos minor crosses 
behind, opposite the sixth dorsal vertebra. The right pneu- DESCRIPTIVE ANATOMY. 
176 
mogastric nerve lies behind while the left lies in front. The 
relation to the aorta is a fourfold one and should be thus stated, 
viz., the oesophagus first has the transverse aorta in front, then 
the descending aorta first to its left side, then behind and, at 
the termination of the oesophagus, the aorta is to the right and 
behind. 
The Abdominal Viscera. 
The cavity of the abdomen is bounded above by the di- 
aphragm, which is a thin arched muscle with its cavity down- 
wards, forming the floor of the chest and the roof of the abdo- 
men. The floor of the abdomen is the floor of the pelvis, i. e., 
the structures which close the outlet of the pelvis. Occasionally 
the floor is given as the brim of the true pelvis and the iliac 
fossae, the true pelvis being then considered a separate cavity. 
Laterally, and in front, from the lower ribs above to the ilium 
below, the abdominal wall is formed of soft tissues, muscles, 
etc., and is the soft, fleshy front wall of the belly. At its upper 
part the cavity is partly circumscribed by the lower ribs-the 
last six or seven; below, by the bony wall of the pelvis; behind, 
by the lumbar portion of the vertebral column; while on each 
side are, above, the floating ribs, below, the pelvic wall, and 
between the two, the soft tissues. For convenience of descrip- 
tion the abdomen is arbitrarily divided into three zones, and 
each of these into three regions, by two horizontal and two 
vertical imaginary lines. The upper horizontal line is drawn 
between the extremities of the ninth ribs: the lower between 
the anterior superior spinous process of the ilia. The vertical 
lines, one on each side, are projected upward from the middle of 
the fold of the groin. 
The names of the nine regions are as follows: The central 
region in the upper zone is the epigastric, the one on either side 
hypochondriac, right and left; the central region in the middle 
zone is the umbilical, the one on either side lumbar, right and 
left; the central region in the lower zone is the hymogastric, 
the one on either side, iliac, right and left. THE VISCERA. 
177 
The contents of the abdomen are the greater part of the 
alimentary canal; the accessory organs of digestion-liver, 
spleen and pancreas; and the genito-urinary organs-kidneys 
and surpa-renal capsules, the bladder and its appendages, 
prostate gland, seminal vesicles and vasa deferentia. The tes- 
ticles are considered with the abdominal viscera, although, in 
the adult, lying in the scrotum, outside the abdominal cavity. 
In the female there are the uterus and its appendages and the 
vagina. Enveloping most of these organs, and lining the walls 
of the cavity, is a serous membrane, called the peritoneum. 
The following are portions of the alimentary canal contained 
in the abdomen: stomach, small intestine, large intestine. 
The stomach is the dilated part which succeeds the oesophagus 
and is about twelve inches long. It terminates, about the line 
which separates the epigastric from the right hypochondriac 
region in the small intestine. 
The small intestine is divided into three parts, duodenum, 
jejunum, and ileum. The duodenum is about nine inches long; 
the jejunum and ileum, together about twenty feet, the jejunum 
comprising the upper two-fifths and the ileum the lower three- 
fifths. The duodenum is again subdivided into three portions. 
The first portion, ascending, or oblique duodenum, is about two 
inches long and terminates at the neck of the gall bladder, on 
the lower surface of the liver, in the right hypochondriac region 
in the second portion, called the descending or perpendicular 
duodenum, which passes vertically downward for about three 
inches into the right lumbar region, about on a level with the 
upper border of the fourth lumbar vertebra, where it terminates 
in the third portion, called the transverse duodenum, which is 
rather more than three inches long and crosses the front of the 
vertebral column obliquely upward and terminates at the left 
side of the body of the second lumbar vertebra, in the jejunum. 
The large intestine is subdivided into three portions called 
coecum, colon and rectum. The coecum is the commencing two 
and one-half inches, lies in the right iliac fossa, and terminates 
in the colon at the opening of the small intestine. The colon 
is divided into the ascending, transverse, and descending colon 
and the sigmoid flexure. The ascending colon passes upward 178 
DESCRIPTIVE ANATOMY. 
through the right lumbar region into the right hypochandriac. 
At the under surface of the liver it curves sharply to the left, 
forming the hepatic flexure of the colon, and becomes the trans- 
verse colon. The transverse colon passes downward and to the 
left, crosses the abdomen between the epigastric and umbilical 
regions and rising into the left hypochondriac region forms 
another abrupt curve at the lower end of the spleen, called the 
splenic flexure of the colon, and becomes the descending colon. 
The descending colon passes downward through the left lumbar 
region into the left iliac where it becomes the sigmoid flexure. 
The sigmoid flexure is that portion of the gut which passes 
from the left iliac fossa into the pelvic cavity to the middle of 
the sacrum where it becomes the rectum. The colon is about 
four feet in length. The rectum is the last four inches of the 
large intestine and terminates the alimentary canal at the anus, 
about the middle of the floor of the pelvis. 
The liver lies in the upper zone of the abdomen, stretching 
nearly across the cavity just beneath the roof. The spleen is 
in the left hypochondriac region. The pancreas lies transversely 
behind the stomach, between the spleen and perpendicular duo- 
denum, crossing the front of the body of the first lumbar verte- 
bra. Each of the two kidneys is beside the lumbar portion of 
the spinal column, on the front of the posterior abdominal wall. 
The urinary bladder and its appendages are found in the pelvis 
just behind the os pubis. The uterus and vagina in the female 
are interposed between the rectum and bladder. 
Reflections of the Peritoneum. 
The peritoneum, being a serous membrane, is a closed sac, 
one layer covering the viscera, and called the visceral layer, 
and the other lining the walls and called the parietal layer. 
The existence of the peritoneum renders the motions of the 
viscera upon one another, and upon the abdominal walls, easy 
and harmless, and furnishes bonds of connection between them 
and the walls of the containing cavity. Being a closed sac its 
continuity can be demonstrated by the fact that in following 
it, transversely or vertically, it can be traced back to the point THE VISCERA. 
179 
of departure. The folds it makes from above downward are the 
most important and will be first stated. 
It leaves the lower surface of the diaphragm in two layers, 
which pass one to the upper, the other to the lower, edge of 
the posterior border of the liver. The upper layer covers the 
upper surface of the liver, curves around the anterior border 
and coats the lower surface as far back as the transverse 
fissure, where it meets the lower layer, which has covered the 
lower surface from the posterior border to the transverse fissure. 
The two layers, having thus enveloped the liver, leave it at the 
transverse fissure and pass downward to the stomach, forming 
between these two organs the gastro-hepatic or the lesser omen- 
tum. They reach the stomach at its upper border and divide, 
one passing over the front and one over the back, and meet again 
at the lower border. The two layers leave the stomach at its 
lower border and pass downward to the transverse colon, pass 
over it without touching, and usually descend almost to the 
brim of the pelvis, just behind the anterior abdominal wall; 
they then reverse their course, run upward, just posterior to 
their descending course, reach the transverse colon, and, separat- 
ing, enclose it. That part of the peritoneum extending between 
the lower border of the stomach and the transverse colon is 
called the greater omentum. The two layers, having enveloped 
the transverse colon, meet at its posterior border and pass back 
to the posterior abdominal wall, where they form the transverse 
mesocolon, which loosely holds the transverse colon to the pos- 
terior abdominal wall. The two layers now finally separate; 
one goes up the posterior abdominal wall to the lower surface 
of the diaphragm, where its course was first taken up, thus par- 
tially enclosing a space behind the stomach called the lesser 
cavity of the peritoneum, which communicates with the general 
cavity through an opening behind the oblique duodenum, called 
the foramen of Winslow; the other layer passes forward to 
envelope the coils of the jejunum and ilium and returns to the 
posterior abdominal wall, forming a double layered fold, called 
the mesentery, holding the intestine to the abdominal wall. The 
attachment of the mesentery is thus stated: from the left side 
of the body of the second lumbar vertebra downward and to 180 
DESCRIPTIVE ANATOMY. 
the right; to the right sacro-iliac synchondrosis. After 
forming the mesentery the peritoneum descends the posterior 
abdominal wall to the brim of the pelvis, passes down its pos- 
terior wall, covering the upper inch or inch and a half of the 
rectum in front, leaves the front of the rectum, strikes the 
back part of the base of the bladder, in the male, covers the 
back, sides and posterior half of the top of the bladder, and 
leaves the bladder to mount on the posterior face of the anterior 
abdominal wall and pass upward upon it to reach its starting 
point on the lower surface of the diaphragm. 
In the female, when the peritoneum leaves the front of the 
rectum, it passes to the lower wall of the vagina, covering its 
upper inch, then strikes the uterus passing up its back and 
turning down its front whence it passes to the bladder. In 
mounting over the top of the uterus it also passes over the ovary 
and its ligament, on each side, thus forming on each side a 
double layered fold stretching between the sides of the uterus 
and the lateral walls of the pelvis, and called the broad liga- 
ment of the uterus. Between these two layers on each side 
are the ovary and its ligament, the round ligament of the uterus 
and the fallopian tube. 
Followed transversely around the abdomen, about its middle, 
the peritoneum presents the following folds: commencing on 
the anterior abdominal wall it can be followed toward the left 
to the posterior abdominal wall, where it reaches the descending 
colon and pass over it, covering it from half to three-fourths 
around; and, leaving it at a corresponding line on the inner 
side, it reaches the vertebral column where it turns forward 
to envelope the folds of the jejunum and ilium and to pass 
back on itself to the vertebral column, forming the mesentery; 
it then runs out on the posterior abdominal wall to reach the 
ascending colon, passes over its front, covering it from half to 
three-fourths around, and, leaving it, again reaches the ab- 
dominal wall along which it runs to the place of departure. THE VISCERA. 
181 
Relations of the Abdominal Viscera. 
The Stomach. 
The stomach lies in the upper zone, in the left hypochondriac 
and epigastric regions, generally terminating in the duodenum 
on the line which separates the epigastric from the right hypo- 
chondriac region, but occasionally passing more or less into the 
latter. Its long axis is directed from above downward, from 
left to right and from behind forward; one surface looks for- 
ward, the other backward; one border, the shorter, or lesser 
curvature, upward, the other, the long, or greater curvature, 
downward; the large end is to the left, the small, to the right. 
It is continuous with the duodenum at the right end. Its upper 
border is held to the lower surface of the liver by the lesser 
omentum; its lower border is indirectly held to the transverse 
colon by the greater omentum; its left end is connected with the 
spleen by the gastro-splenic omentum. Above it are the di- 
aphragm and the left lobe of the liver; below is the transverse 
colon, indirectly held to it by the great omentum; to the right 
is the duodenum; to the left is the spleen, whose concave inner 
surface is in contact with the convex left extremity of the 
stomach; behind is the pancreas, immediately above which is 
the coeliac axis with its branches, and the semi-lunar ganglia, 
and behind these is the abdominal aorta; in front is the anterior 
abdominal wall, partly separated from the stomach by the left 
lobe of the liver. It has a complete peritoneal coat which forms 
for it three ligaments, the lesser omentum holding it to the 
liver, the great omentum suspending the transverse colon and 
the gastro-splenic omentum binding together the spleen and the 
stomach. The pyloire orifice corresponds to the level of the 
upper border of the first lumbar. The cardiac to the seventh 
left chondrosternal articulation or upper border of the eleventh 
dorsal. 182 
DESCRIPTIVE ANATOMY. 
The Oblique Duodenum. 
The oblique duodenum (pars superior) commences at the 
right extremity of the stomach, usually on the line which sepa- 
rates the epigastric from the right hypochondriac region, and 
passes upward and to the right, in the latter region, to ter- 
minate in the descending duodenum at the neck of the gall 
bladder on the lower surface of the liver on a level with the 
first lumbar vertebra. It lies in the right border of the lesser 
omentum and has behind it the hepatic artery, the common 
bile duct and the portal vein. The duct is furthest to the right, 
the artery to the left, while the vein lies between and behind the 
two. In front and above is the liver. It is completely invested 
by peritoneum. 
The Perpendicular Duodenum. 
The PERPENDICULAR, or DESCENDING DUODENUM (pars de- 
scendens), commences at the termination of the oblique duode- 
num, at the lower surface of the liver, at the neck of the gall 
bladder in the right hypochondriac region, and descends ver- 
tically into the lumbar region to terminate in the transverse 
duodenum, about on a level with the body of the fourth lumbar 
vertebra. It lies behind the peritoneum, being covered by it 
only in front. Behind it has the right kidney and in front the 
ascending colon; to the left it is adherent to the head of the 
pancreas. 
The Transverse Duodenum. 
The tranverse duodenum (pars horizontalis inferior) com- 
mences where the oblique terminates, in the right lumbar region, 
on a level with the body of the fourth lumbar vertebra, and 
passing upward and to the left, across the body of the third 
lumbar vertebra, terminates in the jejunum at the left side 
and lower border of the body of the second lumbar vertebra. 
The last inch is fourth part, or pars ascendens. It lies behind 
the peritoneum, between the diverging layers of the transverse 
meso-colon, so that it is covered by peritoneum only in front. 
Above it is the lower border of the pancreas, from which it is THE VISCERA. 
183 
separated by the superior mesenteric artery and vein; in front 
are the transverse colon and the superior mesenteric artery and 
vein. Behind it are the aorta and inferior vena cava. 
The Jejunum and Ileum. 
The remaining twenty feet of the small intestine, following 
the duodenum, are thrown into coils called the convolutions of 
the small intestine, and are found chiefly in the umbilical and 
hypogastric regions, falling off, however, into surrounding 
regions, some being always found in the pelvis between the 
rectum and bladder in the male and between the rectum and 
uterus in the female. The jejunum comprises the upper two- 
fifths of the intestine and begins where the duodenum termin- 
ates, at the left side of the body of the second lumbar vertebra. 
The ileum is the lower three-fifths, and terminates in the right 
iliac region by opening into the large intestine two and one-half 
inches above its commencement. 
The convolutions are completely enveloped by the peritoneum, 
which holds them by a double-layered fold or mesentery to the 
posterior abdominal wall. In front they are separated from 
the anterior abdominal wall by the great omentum; above is 
the transverse colon; to the right the ascending; to the left, 
the descending colon; behind the vertebral column, abdominal 
aorta and inferior vena cava. 
The Coecum. 
The Ccecum is the commencement of the large intestine. It 
is two and one-half inches long and terminates in the colon at 
the opening of the small intestine. It lies in the right iliac fossa 
or region, and is generally completely invested by peritoneum. 
Attached to it is the vermiform appendix, a blind tube about 
the size of a goose quill and from four to six inches long. It 
opens into the inner back wall of the coecum, just below the open- 
ing of the ileum, and not into the bottom. The appendix has a 
complete peritoneal coat and sometimes lies slightly coiled on 
the inner side of the coecum and just below the ileum. It often DESCRIPTIVE ANATOMY. 
184 
drops over the brim of the pelvis, crossing the iliac vessels- 
the thin vein being often endangered in breaking adhesions 
resulting from inflammation of the appendix. 
In front, to the outer side and behind the coecum has the 
abdominal wall. Internally there are convolutions of the small 
intestine, while to its inner and posterior aspect are the iliac 
vessels, separated from it, however, by the parietal layer of 
the peritoneum. 
The Ascending Colon. 
The ascending colon commences where the coecum termin- 
ates, in the right iliac region, at the opening for the ileum, and 
passes upward through the right lumbar region into the right 
hypochondriac region, where it terminates by becoming the 
transverse colon, forming the hepatic flexure of the colon at the 
lower surface of the right lobe of the liver, to which it is held 
by a fold of the peritoneum, being covered by it in front from 
one-half to three-fourths around. In front, behind, and to the 
outer side is the abdominal wall; to the inner side, the convolu- 
tions of the small intestine, and the inferior vena cava, which 
is separated from it by the peritoneum; behind, the perpendicu- 
lar duodenum and right kidney, the duodenum being to the 
inner and posterior aspect, the kidney behind and external to 
the duodenum. 
The Transverse Colon. 
The transverse colon commences at the termination of the 
ascending colon, at the lower surface of the liver, in the hepatic 
flexure of the colon, and passes obliquely downward and to 
the left, crosses the abdomen between the upper and middle 
zones, and, rising into the left hypochondriac region, terminates 
by forming the splenic-flexure of the colon at the lower end of 
the spleen and becomes the descending colon. Its course is 
curved with its convexity downward and forward. It is entirely 
covered by peritoneum, which holds it by a long double-layered 
fold, the transverse meso-colon, to the posterior abdominal wall 
and by a small band to the lower end of the spleen. It is in- 
directly held to the greater curvature of the stomach by the THE VISCERA. 
185 
great omentum. In front it is separated from the anterior 
abdominal wall by the great omentum; behind are the pancreas, 
the transverse duodenum, and superior mesenteric vessels; 
above are the liver, stomach and spleen; below, the convolu- 
tions of the small intestine. 
The Descending Colon. 
The descending colon begins where the transverse colon 
ceases, in the left hypochondriac region at the lower end of 
the spleen, and passing downward through the left lumbar 
region terminates in the left iliac region by becoming the sig- 
moid flexure of the colon. It lies behind the peritoneum, cov- 
ered by it in front from one-half to three-fourths around. To 
its front and outer side is the abdominal wall behind the left 
kidney; to the inner side are the convolutions of the small 
intestine. 
The Sigmoid Flexure. 
The sigmoid flexure of the colon begins by being the continu- 
ation of the descending colon in the left iliac region and, passing 
down into the pelvic region terminates on the middle of the 
third piece of the sacrum by becoming the rectum. The gut 
presents many differences in position, but, when empty, is usu- 
ally found passing downward and to the right, then falling over 
the brim of the pelvis and resting against its own lower por- 
tion and the beginning of the rectum. It is completely invested 
by peritoneum, which holds it by a fold of variable length to the 
abdominal wall. It crosses the pelvic brim in front of the 
ureter, from which, as well as from the iliac vessels, it is sepa- 
rated by peritoneum. In the pelvis it lies in front of the in- 
ternal iliac vessels and sacral plexus of nerves, and comes in 
contact, on its inner side, with convolutions of the small in- 
testines, the side of its own terminal portion and the side of 
the rectum. In the female it rests against the ovary, uterus 
and vagina. Between it and the vagina and uterus, in the 186 
DESCRIPTIVE ANATOMY. 
female, and bladder in the male, are interposed some convolu- 
tions of the small intestines. 
The Rectum. 
The RECTUM begins by being the continuation of the sigmoid 
flexure at the middle of the third piece of sacrum and termin- 
ates at the anus. It passes straight down the middle line, con- 
forming to the curve of the sacrum and coccyx, until it reaches 
the tip of the latter bone, when it turns backward, running in 
this direction downward and backward for about an inch and 
a quarter, when it terminates at the anus. At its commence- 
ment the recturn is covered by peritoneum about half way 
around, but the peritoneum gradually leaves the sides of the 
gut as it descends, and, after a course of about an inch, leaves 
the front of the rectum to pass to the back of the bladder in 
the male, or the back of the vagina, in the female. That por- 
tion of the rectum which is covered by peritoneum has upon its 
front convolutions of the small intestine which separate it from 
the bladder, in the male, or the uterus and vagina, in the female. 
Behind, the rectum rests upon the front of the sacrum from 
which it is separated by the pyriformis muscle, and the lower 
sacral nerves. In front, below the peritoneum, it has the base 
of the bladder, prostate gland, seminal vesicles, and vasa defer- 
entia, and is crossed on its side by the ureters. In the female 
the vagina rests upon the front of the gut, at first firmly at- 
tached to it, but separated from it below by a widening interval 
filled in by the perineal body. The last inch and a quarter of the 
rectum is surrounded by fibres of the levator ani muscle, and 
is not properly an abdominal viscus, as it lies in the ischio-rectal 
fossa. 
The LIVER is found in the upper zone of the abdomen, the 
greater part being in the right hypochondriac and epigastric 
regions, but projecting, to a greater or less extent, into the 
left hypochondriac. Its long axis is transverse; its sharp 
notched border is in front and below, nearly corresponding to 
The Liver. 187 
THE VISCERA. 
the lower margin of the ribs on the right; its thick border is 
backwards, resting against the diaphragm and grooved near 
the middle for the inferior vena cava, and also, near the left 
end, for the oesophagus; its convex surface is above; its large 
end is to the right. 
It is held in place by five ligaments and is connected to the 
stomach by the lesser, or gastro-hepatic omentum. Four of 
its ligaments are formed by the peritoneum, while the fifth, 
called the round ligament, is the remains of the obliterated 
umbilical vein. The peritoneum reaches the liver by two very 
short layers, which seize the one the upper the other the lower 
edge of its posterior border. These layers, on the posterior 
border, are separated by a considerable triangular space; but 
at each end they come together and form the right and left 
lateral ligaments. Between these lateral ligaments the layers 
surrounding the triangular space form the coronary ligament. 
The upper layer is diverted forward from the liver, at a point 
about one-third the length of the liver from its left end, across 
the upper surface of the liver so as to surround the round 
ligament by a double-layered fold called the suspensory, or 
longitudinal, ligament, which holds the liver to the diaphragm. 
The round ligament is that part of the obliterated umbilical 
vein which passes backward from the anterior abdominal wall 
to the notch in the anterior border of the liver, lying between 
the two layers of the longitudinal ligament. The peritoneum 
reaching the liver in the manner described, passes over it, one 
layer over the upper surface, around the anterior border to the 
transverse fissure where it meets the other layer, which has 
run forward on the lower surface from the posterior border, 
thus furnishing an almost complete peritoneal coat for the organ. 
Above the liver is the diaphragm, which separates it from 
the thorax, containing the heart and lungs; below are, from 
right to left, the right kidney and supra-renal capsule, lying 
near the posterior border of the liver; in front of these, and near 
the anterior border, the hepatic flexure of the colon; behind 
and to the left of this, near the neck of the gall bladder, the 
oblique duodenum; to the left of this the upper border of the 
stomach, held to the liver by the lesser omentum, and, to the 188 
DESCRIPTIVE ANATOMY. 
left of this, the spleen, suspended from the under surface of 
the diaphragm by the suspensory ligament. The spleen is a 
relation only when the liver or spleen is much enlarged. The 
posterior border of the liver has upon it the inferior vena cava, 
to the left of this the abdominal aorta and still further to the 
left the oesophagus. On its under surface should be mentioned 
the gall bladder, considered with the liver itself. 
The Spleen. 
The spleen is confined to the left hypochondriac region. Its 
long diameter is vertical; its thin notched border is anterior; 
its smallest end is below; its convex surface, external. It has 
a complete peritoneal coat and is held in position by folds of 
peritoneum, one fold, called the suspensory ligament, passing 
from its upper end to the diaphragm, the other called the gastro- 
splenic omentum, passing from its inner face to the great end 
of the stomach. A third small fold extends from its lower end 
to the splenic flexure of the colon. 
Above is the diaphragm from which it is sometimes sepa- 
rated by the liver; below is the splenic flexure of the colon; 
behind the lower end is the left kidney and supra-renal capsule; 
in front, the anterior abdominal wall; internal to it are the 
great end of the stomach and the tail of the pancreas; externally 
it corresponds to the ninth, tenth and eleventh ribs, from which 
it is separated by the diaphragm, the left pleura and the lower 
border of the left lung. 
The Pancreas. 
The pancreas extends from the inner face of the spleen on 
the left to the descending duodenum on the right. Its long 
diameter is transverse; its large end to the right; one surface 
looks forward, the other backward; one border is above, the 
other below. 
It rests on the front of the posterior wall of the abdomen, 
crossing the body of the first lumbar vertebra. It is behind the 
peritoneum, which covers it only in front. To its right is the 
perpendicular duodenum, to which it is closely adherent; to its THE VISCERA. 
189 
left is the inner face of the spleen to which its tail is held by 
the peritoneum; in front is the stomach; behind its left end is 
the left kidney; below it is the transverse duodenum, from which 
it is separated by the superior mesenteric vessels. 
Its relations to blood vessels are very complex, and may be 
given as follows: it is separated from the vertebral column 
by the inferior vena cava and the abdominal aorta, which gives 
off the coeliac axis on a level with the upper border of the head 
of the pancreas, while the superior mesenteric artery is emitted 
just behind the head; the latter descending behind the pancreas, 
to pass out between it and the transverse duodenum. The coeliac 
axis, resting on the upper border of the head of the pancreas, 
divides into three branches, one of which, the splenic, pursues 
a very tortuous course along its upper border to the inner face 
of the spleen. This artery is accompanied by its vein, which 
passes to the right from the spleen, lying in a deep groove on 
the posterior face of the pancreas just below its upper border. 
Behind the head of the pancreas the splenic vein unites with the 
superior mesenteric vein, which ascends behind the pancreas 
as the companion of its artery, the two forming the portal vein. 
About the middle of its course the splenic vein receives the 
inferior mesenteric vein which passes behind the body of the 
pancreas. Surrounding the coeliac axis are the two semi-lunar 
ganglia of the sympathetic, giving off the numerous branches 
of the solar plexus of nerves, which are in close relation with 
the head of the pancreas. 
The Kidneys. 
The kidneys lie on the front of the posterior abdominal wall, 
extending from about the eleventh rib downward and slightly 
outward to about the crest of the ilium. The right is perhaps 
a little lower than the left, reaching only to the lower border 
of the eleventh rib, while the left reaches to its upper border. 
The kidneys correspond to the last dorsal and the upper three 
lumbar vertebrae. They lie behind the peritoneum, embedded 
in a considerable mass of loose connective tissue, which usually 
contains much fat. The peritoneum is loosely connected to the 190 
DESCRIPTIVE ANATOMY. 
front of the organ by this tissue and can easily be stripped off. 
The long diameter of the kidney is from above downward and 
slightly outward; one face looks forward and slightly outward, 
the other backward and slightly inward; the upper end is, per- 
haps, the larger; the outer border is convex, the inner concave. 
Through most of its extent the kidney rests on the quadratus 
lumborum muscle, separated from it by the anterior lamella 
of the posterior aponeurosis of the transversalis muscle. Along 
its inner edge it lies on the psoas magnus muscle, and behind 
its upper part is the diaphragm, which separates it from the 
pleura. The diaphragm here frequently presents a fissure of 
considerable size, where the muscular tissue is wanting, so 
that, in this event, all that separates the kidney from the pleura 
is a little loose connective tissue. Each kidney has upon its 
upper, inner, front part the supra-renal capsule. The outer 
border is nearly opposite the outer border of the erector spinae 
muscle, and about corresponds to the junction of the posterior 
third with the anterior two-thirds of the crest of the ilium. 
The right kidney has in front and internally the descending 
duodenum and in front of that the ascending colon; along its 
inner border is the ascending vena cava; its upper end is in 
contact with the lower surface of the liver, which may also 
rest on the front of its upper part. The left has on its front 
the descending colon and, at its upper part, the lower end of 
the spleen, the tail of the pancreas and the great end of the 
stomach. 
The Bladder-in the Male. 
The urinary bladder occupies the front portion of the pelvic 
cavity, being confined to it when empty, or nearly so, but rising 
out of it according to its state of distension, occasionally reach- 
ing the level of the umbilicus. It lies just behind the symphysis 
pubis with its long diameter from above downward and back- 
ward, extending from the upper border of the symphysis pubis, 
or a point in the linea alba between it and the umbilicus, vary- 
ing with distension, so that, if prolonged, it would strike the 
lower part of the front of the sacrum. THE VISCERA. 
191 
The large end of the bladder is below and looks downward 
and backward. The viscus is retained in position by its liga- 
ments which are ten in number. Five of these are called false 
ligaments and are furnished by peritoneum, while of the five 
true ligaments four are processes of fascia and one is the re- 
mains of a foetal structure, called the urachus. 
The peritoneum leaves the front of the rectum about three 
inches above the anus, and sweeps in a drooping course to the 
back part of the base of the bladder. This broad fold, ex- 
tending from the front of the rectum to the bladder, is spoken 
of as the two posterior false ligaments. The division between 
them is purely arbitrary, being the middle line of the body. 
On each side, however, the fold presents an antero-posterior 
ridge, produced by the passage of the hypogastric artery from 
the posterior side of the pelvic wall to the side of the lower 
part of the bladder, the artery then passing up the side of the 
back of the bladder to the side of the top, whence it leaps to 
the anterior abdominal wall and approaching its fellow of the 
opposite side, makes for the umbilicus. This fold separates 
the posterior from the lateral false ligaments. 
The peritoneum, reaching the bladder, covers the back part 
of its base, the back of the bladder, the posterior half of each 
side and the posterior half of the top, thence passing to the 
anterior abdominal wall, to which it is guided by the urachus, 
and the obliterated hypogastric arteries. That part of the 
peritoneum extending from the middle of the top of the bladder 
to the anterior abdominal wall is called the superior false liga- 
ment; and that part on each side, extending from the side of 
the bladder to the lateral wall of the pelvis, forms the lateral 
false ligament. 
The four remaining true ligaments are formed by the pelvic 
fascia, which lines the pelvic cavity just beneath the peritoneum. 
From either side of the symphysis pubis a process of this fascia 
is extended to the lower part of the front of the bladder and 
prostate gland, these two being called the two anterior true 
ligaments of the bladder. From the lateral wall of the pelvis, 
on each side, a process of fascia passes to the side of the bladder, 192 
DESCRIPTIVE ANATOMY. 
the two being known as the two lateral true ligaments of the 
bladder. 
The front of the bladder is separated from the back of the 
symphysis pubis only by a little loose connective tissue. The 
neck of the bladder is received into the back part of the prostate 
gland and is continuous with the urethra, being about an inch 
behind and below the pubic arch. 
The posterior face of the bladder is separated from the 
rectum usually by some convolutions of the small intestine. 
The base of the bladder rests on the front of that part of the 
rectum which is found descending the front of the sacrum, and 
is adherent to it. Piercing the posterior part of the base of 
the bladder on each side is the ureter, the two being about two 
inches apart, and each having just internal to it the vas defer- 
ens, which, entering the abdomen at the internal abdominal 
ring, passes to the side of the top of the bladder, descends to 
its posterior face, runs forward and inward along its base to 
terminate at the front of the base by uniting with the duct, 
which forms the seminal vesicle to produce the ejaculatory 
duct. The seminal vesicles lie, one on each side, on the side 
of the base of the bladder. They are pear-shaped, the base 
being behind and the apex forward and inward at the back 
of the prostate gland. 
The Bladder in the Female. 
In the female the bladder, in general terms, occupies the same 
position as in the male. There is no prostate gland, vas defer- 
ens, nor seminal vesicle. The base of the female bladder rests 
on the upper wall of the vagina and on the lower part of the 
front of the uterus, which two separate it from the rectum. 
Otherwise the relations are about the same as in the male. 
Description of the Separated Viscera. 
The Stomach. 
In shape the stomach is a curved cone, with one border 
shorter than the other, and its two sides, called anterior and THE VISCERA. 
193 
posterior faces, somewhat flattened. The short border is known 
as the lesser curvature, the long as the greater curvature. The 
large end of this cone is to the left and is called the splenic 
end, because it is hugged by the spleen. At the left extremity 
of the lesser curvature, two or three inches from the left end, 
is an aperture for the oesophagus, called the cardiac orifice. 
The splenic end of the stomach is the dilated cul-de-sac bulging 
beyond this. 
The right extremity of the stomach is much smaller than 
the splenic end and is called the pyloric extremity, because the 
opening of this end of the stomach in the duodenum is called 
the pylorus. It is the smallest part of the alimentary canal, 
being only an inch and a half in diameter. The position of 
the stomach is not directly transverse, but somewhat oblique, 
its long diameter being from above downward, forward, and to 
the right, the cardiac orifice being on a higher level and farther 
back than the pyloric. When empty, the anterior and posterior 
faces look almost directly forward and backward respectively. 
The longest diameter of the stomach is about twelve inches, 
and it can receive from one to two quarts at a time. 
The Small Intestine. 
The duodenum succeeds the stomach. It is about nine inches 
in length and forms a horseshoe-shaped curve whose convexity 
is to the right. It is divided into three portions. The first 
portion, beginning at the stomach, is about two inches in 
length, and is called the oblique portion. It passes upward, 
backward and to the right. The second portion, called the 
descending or perpendicular duodenum, is about three inches 
long and passes downward. The third portion, called the trans- 
verse duodenum, begins where the descending terminates and 
passing across the vertebral column, terminates in the jejunum, 
or second portion of the small intestine. The duodenum ter- 
minates at the left side of the second lumbar vertebra f but 
the point where the jejunum becomes the ileum is arbitrary 
and ill defined. The jejunum begins where the duodenum ter- 
minates and comprises the upper two-fifths of the remainder 194 
DESCRIPTIVE ANATOMY. 
of the gut. The ileum comprises the remaining three-fifths 
and terminates in a suddenly dilated portion called the large 
intestine. The jejunum and ileum together are about twenty 
feet long. They lie coiled up chiefly in the umbilical and hypo- 
gastric regions, producing an appearance somewhat similar to 
the upper surface of the brain, from which they are called the 
convolutions of the small intestine. 
The Large Intestine. 
The large intestine begins by a sudden dilatation just below 
the termination of the small intestine in the right iliac region, 
and extends to the termination of the alimentary canal at the 
anal orifice. 
The large intestine is about five feet in length. It is sinuous 
in its course and is divided into three portions, caecum, colon 
and rectum. 
The entrance of the ileum is not into the extremity of the 
large intestine, but two or three inches above its commence- 
ment. The blind pouch or cul-de-sac, which extends below this 
orifice is called the coecum. This is the largest portion of the 
large intestine; it is about two and a half inches in length, 
lies in the right iliac fossa, is continuous with the colon above, 
and has projecting from its lower inner back part a tail-like 
hollow projection called the vermiform process, or appendix, 
which is from four to six inches in length and lies just below 
the terminal part of the ileum, its cavity being continuous with 
that of the coecum. 
The colon is the second portion of the large intestine. It com- 
mences at the entrance of the ileum, which is the mark of divi- 
sion between it and the coecum, in the right iliac region, and 
passes upward through the right lumbar region to the lower 
surface of the liver, in the right hypochondriac region. This 
portion of the gut is called the ascending colon. At the lower 
surface of the liver it makes a bend called the hepatic flexure 
of the colon, and turns to the left across the abdominal cavity. 
This portion is called the transverse colon and its course cor- 
responds to the superior horizontal line of the abdomen. At 
the lower end of the spleen, in the left hypochondriac region, THE VISCERA. 
195 
the colon makes another bend, called the splenic flexure, and 
turns downward to pass through the left lumbar region to the 
left iliac fossa, as the descending colon. In the left iliac fossa 
it makes another turn, first upward and to the right and then 
downward and to the left, forming the sigmoid flexure, which 
terminates at the middle of the third piece of the sacrum by 
becoming the rectum. The rectum begins where the sigmoid 
flexure terminates and passes downward on the front of the 
sacrum, to terminate at the anus, being approximately straight 
in its course-hence its name. 
Structure. 
The following coats, with slight exceptions, are common to 
the whole of the alimentary canal found in the abdomen: 
1st. The visceral layer of the peritoneum. 
2d. The interior coat is mucous membrane. 
3d. Between these two are found the longitudinal muscular 
fibres, lying next to the serous coat, and 
4th. The circular muscular fibres, next to the mucous coat. 
These coats are held to one another by interposed connective 
tissue, or areolar tissue. Each part, also, presents some point, 
peculiar to itself. 
The stomach has, 1st, the serous coat which, besides invest- 
ing it, passes off to adjoining parts, forming the omenta of the 
stomach which serve to retain it in its position. It is held to 
the liver by the gastro-hepatic, or lesser omentum, to the spleen 
by the gastro-splenic omentum and to the transverse colon by 
the gastro-colic, or greater omentum. 
2d. Just beneath the serous coat is the longitudinal muscular 
coat. 
3d. Just beneath this is the circular muscular coat, which 
is thickest toward the pyloric extremity, while the longitudinal 
is thickest at the lesser curvature. 
4th. The fourth coat is a parietal one, of oblique muscular 
fibres which diverge from the cardiac end of the stomach be- 
neath the circular fibres and terminate before reaching the 
pyloric orifice. 196 
DESCRIPTIVE ANATOMY. 
5th. The fifth coat is the terminal mucous coat, which, when 
the stomach is empty, is thrown into longitudinal ridges, called 
rugae, which disappear when the stomach is distended. At the 
pylorus the mucous coat is thickened, and beneath this thicken- 
ing is an aggregation of the circular fibres so as to produce a 
sudden contraction of the tube. This appearance is known 
as the pyloric valve. 
The duodenum has four coats: 1st, serous; 2d, longitudinal 
muscular; 3d, circular muscular; 4th, mucous membrane. In 
the commencement of the gut the mucous membrane is smooth, 
but it is soon thrown into folds, which pass around the gut 
from three-fourths to five-sixths of its circumference; called 
valvulse conniventes. These valvulae conniventes are continued 
down into the jejunum and ileum, but gradually decrease in 
size and in the ileum are inconspicuous. They are permanent 
folds, not affected by distension. 
On the lower inner part of the perpendicular duodenum is a 
prominence of the mucous membrane, called a papilla, on whicn 
is seen the aperture for the common bile duct and the pan- 
creatic duct. 
The jejunum and the ileum have the same coats, in the same 
order, as the duodenum. Studding the inner surface of the 
small intestine are numberless hair-like microscopic projections 
from the mucous membrane called villi; and besides these, and 
numerous mucous follicles which have their seat throughout the 
small intestine, there are some glandular bodies which have 
special seats. 
In the duodenum there are numerous small glands, about the 
size of a pin's head, lying just beneath the mucous membrane 
and opening by ducts on its free surface, known as the glands 
of Brunner. Scattered throughout the small intestine, but much 
more numerous in the lower part of the ileum, are small, round, 
grayish bodies, in the mucous membrane, which have no duct 
and are called solitary glands. In the lower part of the ileum, 
and extending upward ten feet, or more-in a few instances 
into the duodenum-are found a number of dark, oblong, gray- 
ish patches, called Peyerian glands or Peyer's patches. They 
are twenty to thirty in number. Sometimes there are as many THE VISCERA. 
197 
as forty. The long diameter of these patches is in the direction 
of the long diameter of the gut. They are made up of an 
aggregation of the solitary glands and become diseased in ty- 
phoid fever. 
The opening of the small intestine into the large is by means 
of a horizontal slit-like opening, situated on the inner side 
of the large intestine two and a half inches above its com- 
mencement, and guarded by a valvular arrangement called the 
ileo-coecal, or ileo-colic valve. This valve consists of two pro- 
jections into the cavity of the large intestine, one above and 
the other below the button-hole-like aperture, each segment 
being a fold of mucous membrane covering circular fibres of 
muscular tissue. 
The large intestine, like the small, has four coats, external 
serous, internal mucous, and, between these, two muscular, 
outer longitudinal, inner, circular. From the commencement 
of the large gut to the rectum the longitudinal coat is not dis- 
tributed uniformly around the gut, but the fibres are gathered 
into three narrow flat bands placed one in front, one on the 
back, and one on the concave, inner side of the gut. These 
bands are shorter than the other coats of the gut, and in conse- 
quence the other tunics are thrown into folds with correspond- 
ing depressions. These prominences are known as the saculi 
of the large intestine. Towards the termination of the colon 
these bands begin to be diffused, and in the rectum, the longitu- 
dinal fibres are again evenly distributed and of equal length 
with the other coats. The mucous membrane, in consequence 
of the shortness of the longitudinal muscular fibres, is also 
thrown into saculi. Beneath it, especially in the upper part of 
the gut, are seen a number of solitary glands which differ from 
those in the small intestine in having a duct. 
The rectum presents some important departures from the 
above description. It is divided into two portions. The first 
portion extends from the commencement of the gut until it 
reaches the point opposite the tip of the coccyx; the second is 
the last inch of the gut, which here inclines backward to ter- 
minate at the anus. The rectum presents the same four coats, 
in the same order, with the following exceptions: The serous 198 
DESCRIPTIVE ANATOMY. 
coat is a partial one, covering the gut for only an inch at its 
upper front part, from which point it mounts to the bladder. 
The fibres of the longitudinal muscular coat becomes much 
more distinct, and of a reddish color, in the lower part of the 
gut; and, when they reach its extremity, they do not stop short, 
but turn upward to run along the inner face of the circular 
fibres, which separate them from the descending longitudinal 
fibres, while the mucous membrane lies between them and the 
cavity of the gut. These ascending longitudinal fibres are 
gathered into separate bundles, or columns, which pass up for 
an inch or two before ceasing, and throw the mucous membrane 
into ridges with intervening depressions called rectal pouches. 
Towards the lower extremity of the rectum the fibres of the 
circular muscular coat are aggregated into a thickened ring, 
internal sphincter ani, and just above this the cavity of the 
gut is considerably dilated, forming a capacious reservoir in 
cases of long continued constipation. 
The Liver. 
The liver stretches across the abdomen just beneath its roof, 
lying in the right hypochondriac, the epigastric, and, to some 
extent, the left hypochondriac region. It is semi-ovoidal in 
shape, weighs about four pounds, is about twelve inches long, 
six broad and three thick, at its thickest part; in color it is 
a dull red with, occasionally, a purplish, or yellowish tinge. It 
is, in structure, a solid glandular organ. For study it is divided 
into an upper and a lower surface, an anterior and a posterior 
border, five ligaments, and an excretory apparatus. 
The upper surface is smooth and convex, being moulded on 
the lower surface of the diaphragm. It presents a glistening 
appearance due to the visceral layer of peritoneum. The peri- 
toneum, passing from the diaphragm to the liver in an antero- 
posterior fold, strikes the liver nearer the left than the right 
extremity. This fold, the longitudinal ligament, is a mark of 
division between the two lobes, all that portion lying to the 
right being known as the right lobe, while the much smaller 
portion, lying to the left, is the left lobe. THE VISCERA. 
199 
The anterior border is thin and sharp and has a notch at the 
point where the longitudinal ligament intersects it, which also 
marks the division between the lobes. The anterior border is 
on a level with the lower border of the ribs, though, when the 
liver is enlarged, it may be felt through the abdominal parietes. 
The posterior border is thick and rounded and marked by a 
notch where it is intersected by the longitudinal ligament, a 
third mark of division between the two lobes. The openings 
for the hepatic veins are found on this border, and it is grooved 
for the inferior vena cava and oesophagus. 
The lower surface is marked from before backwards by a 
fissure called the longitudinal, which is just opposite the longi- 
tudinal ligament on the upper surface, and extends from the 
notch in the anterior to that in the posterior border. It is the 
fourth mark of division between the lobes. The lower surface 
of the right lobe presents a deep groove, called the transverse 
fissure, which runs to the right from the longitudinal fissure 
which it strikes about its posterior third. In this fissure are 
found the hepatic duct, to the right, and slightly in front, the 
hepatic artery to the left, and, between and behind the two, 
the portal vein. That portion of the longitudinal fissure which 
is behind the intersection of the transverse, is called the venosal 
fissure, and the portion in front the umbilical fissure. The 
latter is frequently crossed by a strip of liver tissue called the 
pons hepatis. Lying in front of the transverse fissure, and 
producing an impression on the lower surface of the right 
lobe, is the gall bladder; and between this and the longitudinal 
fissure is a square-shaped portion of liver tissue called the lobus 
quaratus, whose limits are, in front, the anterior border of the 
liver, behind, the transverse fissure, to the right the gall bladder, 
to the left the longitudinal fissure. Behind the transverse fissure 
is another portion of liver tissue, which has received the name of 
lobus Spigelii. It is three sided, having in front the transverse 
fissure, to the left the venosus portion of the longitudinal fissure, 
and to the right the groove made by the inferior vena cava. 
Running out to the right from the front of the lobus Spigelii, 
just behind the transverse fissure, is a ridge, called the lobus 
caudatus. Near the posterior border there is a depression on 200 
DESCRIPTIVE ANATOMY. 
the lower surface of the right lobe made by the right kidney 
and its supra-renal capsule. 
The liver is held in position by processes of peritoneum, called 
ligaments, which are five in number. 
The longitudinal, or suspensory, ligament consists of two 
layers of peritoneum which pass from the lower surface of the 
diaphragm to the upper surface of the liver. These two layers 
separate on reaching the liver, and, except at two places, com- 
pletely invest it. One exception is the space on the lower sur- 
face, occupied by the gall bladder, for the peritoneum leaps 
over the gall bladder, investing it, and leaves the contiguous 
surfaces of liver and gall bladder uninvested. The other ex- 
ception is found at the posterior border, for the two layers 
here diverge, to form the right and left lateral ligaments, which 
are nothing more than the points where the visceral and parietal 
layers come in contact; and between the two diverging layers, 
on the posterior border, there is a triangular space which has 
no serous coat. The two layers, as they skirt this space, are 
known as the coronary ligament. The fifth or round ligament 
is a rounded cord in the front edge of the longitudinal ligament. 
It is the obliterated umbilical vein. 
The excretory apparatus consists of a series of ducts, and a 
reservoir, called the gall bladder. 
The gall bladder is a membraneous pyriform sac, lying on the 
lower surface of the right lobe of the liver, its large end lying 
forward and usually falling short of the anterior border, though 
occasionally projecting beyond it. Its small end lies backward 
and terminates at the transverse fissure in a neck which be- 
comes continuous with a duct called the cystic. This duct is 
about one inch long and unites with the duct from the liver to 
form the common bile duct. The gall bladder has three coats. 
The external serous coat is only a partial one, since it passes 
over the gall bladder from the liver, leaving that portion next 
the liver uninvested. The next coat is fibro-muscular. The 
internal coat is mucous, and, in the neck, it is thrown into spiral 
folds, so that liquid in following the spiral can flow but slowly. 
In the transverse fissure two ducts, one from the right and 
one from the left lobe, unite to form the hepatic duct, which is THE VISCERA. 
201 
about two inches tang and descends to unite with the cystic to 
form the common bile duct-ducts communis choledochus- 
which descends for about three inches to open on a papilla on 
the lower inner part of the perpendicular duodenum. 
The Pancreas. 
The pancreas is a pale, lobulated gland. It is six or seven 
inches long and varies in thickness from an inch and a half to 
less than half an inch. It weighs about three ounces and lies 
horizontally behind the stomach, with its large end or head 
embraced by the concavity of the descending duodenum, and 
its small end or tail in contact with the inner aspect of the 
spleen. It crosses the body of the first lumbar vertebra, which 
renders its posterior aspect concave, whereas its anterior is 
convex. The head is much the larger portion of the organ and 
sends downward, at right angles to the body, a considerable pro- 
jection from which the gland has been likened to a hammer. 
The head also furnishes a prominence backward and to the 
left which is sometimes called the lesser pancreas, and is found 
lying behind the superior mesenteric vessels. 
The pancreatic duct. The pancreatic juice is collected and 
conveyed away by a duct called the pancreatic, or canal of 
Wirsung, which commences in the tail of the organ by a forked 
origin. The two branches soon unite and the resulting duct, 
as it passes to the right grows by momentary accessions until 
it reaches the right extremity of the organ, where it pierces 
the coats of the perpendicular duodenum to open on the papilla 
for it and the common bile duct. 
Somewhere, just before leaving the pancreas, it receives the 
duct from the lesser pancreas. 
In structure the pancreas is a lobulated gland. It lies behind 
the peritoneum, and, consequently, has a serous coat only in 
front. 
The Spleen. 
The spleen lies vertically in the left hypochondriac region. 
It is completely invested by peritoneum, which forms two folds 202 
DESCRIPTIVE ANATOMY. 
to retain it in position. The first is called the suspensory liga- 
ment and suspends the spleen by its upper extremity from the 
lower surface of the diaphragm; the second, the gastro-splenic 
omentum, passes between the inner surface of the spleen, and the 
contiguous large end of the stomach. 
In color the spleen is a dark red; in shape, semi-ovoidal; in 
consistence, extremely fragile; in size, about six inches long, 
three broad and one and one-half thick; in weight, about seven 
ounces. It may be divided, for study, into two surfaces, two 
borders and two extremities. The external face is convex to 
correspond with the sweep of the abdominal wall; the internal, 
flat, or perhaps, concave, to hug the great end of the stomach, 
and marked about its centre by a vertical groove, called the 
hilum, where the branches of the splenic artery find ingress 
and the veins egress, and where the gastro-splenic omentum is 
attached. The upper extremity is much larger than the lower, 
which is thin and pointed. The posterior border is thick and 
rounded; the anterior, thin, sharp, and marked by one or more 
notches. 
The Kidneys. 
The kidneys are a pair of organs found, one on each side of 
the vertebral column in the lumbar region, the left extending 
from the upper border of the eleventh rib to the crest of the 
ilium, the right from the lower border of the same rib, being 
one-half inch lower than the left They about correspond to 
the twelfth dorsal and first, second, and third lumbar vertebrae, 
and diverge somewhat as they descend. Each is embedded in 
a mass of fat behind the peritoneum, which touches them only 
slightly in front. Perched on the upper, inner part of each 
is the supra-renal capsule. The kidney is about four inches 
long, two broad, and one thick. It is peculiar in outline, hence 
the name reniform. The anterior surface is convex, the pos- 
terior, slightly flattened; the upper end is the larger; the outer 
border is convex, the inner, concave, and presents a deep de- 
pression, called the hilum of the kidney, through which the 
duct and blood vessels pass, in the following order: the renal 
vein in front, the duct, or ureter, behind, and the renal artery THE VISCERA. 
203 
between the two. The hilum leads to a cavity in the organ, 
called the sinus. The kidney weighs four or five ounces. 
Structure. 
The kidney is invested by a fibrous coat, which can be easily 
stripped off, thus exposing the proper tissue, to study which 
the kidney should be split longitudinally, beginning at its ex- 
ternal border and passing through its width. It is then seen 
to consist of two portions, an outer layer, red in color, which 
forms about three-quarters of the organ, and within this is a 
portion of a lighter red forming the remaining fourth. The 
outer is called the cortical, the inner the medullary portion. 
The inner portion is made up of conical masses called pyramids 
of Malpighi; they are arranged with their bases toward the 
cortical portion and their apices toward the hilum and are from 
eight to eighteen in number. Each pyramid consists of hun- 
dreds of straight tubules, leading from the cortical portion, 
where the urine is secreted, to the apex or papilla of the pyra- 
mid, where they discharge the urine. These pyramids are sepa- 
rated by prolongations of the cortical substance, which project 
between them. 
The urine, which drops from the papilla, is carried off by 
coalescing ducts having different names, all of which finally 
terminate in one duct called the ureter, which in turn opens 
into the urinary bladder. The course can best be understood 
by following it from below up. Beginning with the ureter 
we find that, just before it reaches the kidney, it begins to 
enlarge, forming what is called the pelvis of the ureter, which, 
entering at the hilum, occupies the sinus of the kidney. The 
pelvis of the ureter soon divides into three tubes called infundi- 
bula, one infundibulum collecting the urine from each third of 
the organ. Each infundibulum, after a short course, subdivides 
into a number of short tubes called calices, each calyx terminat- 
ing by surrounding the apex of one or more pyramids. The 
course of the urine, then, after secretion in the cortical portion, 
is (1) through the uriniferous tubules, which form the pyra- 
mids of Malpighi, (2) dropping from the apex or papilla it 204 
DESCRIPTIVE ANATOMY. 
falls into (3) the calyx, which, uniting with other calices from 
its third of the organ, forms (4) an infundibulum, which com- 
bines with the other two infundibula to form (5) the pelvis of 
the ureter, which (6) contracts to the ureter proper, which, 
lastly, opens into (7) the bladder. 
The Ureter. 
The ureter commences at the kidney in a dilated portion 
called the pelvis, and, contracting to a small tube-about the 
size of a crow's quill-passes down beside the vertebral column 
to the brim of the pelvis, crossing the common iliac vein and 
artery, near the termination of the latter, descends in the pelvis 
behind the bladder, and approaching its fellow, opens into the 
back part of the base of the bladder. The apertures for the 
two ureters are about two inches apart, and the tubes pierce 
the coats of the bladder in an oblique direction. The length 
of the ureter is from sixteen to eighteen inches. 
The ureter-lying behind the peritoneum-consists of three 
coats, an external fibrous coat, an internal mucous, and, be- 
tween these, an external longitudinal and an internal circular 
muscular coat. This description applies to pelvis, infundibulum 
and calyx. Near the bladder there is another layer of longi- 
tudinal muscular fibres lying between the circular fibres and 
the mucous membrane. 
The Urinary Bladder. 
The bladder is the reservoir for the urine. It is a membra- 
nous sac which lies in the pelvis, just in front of the rectum, 
in the male, and of the uterus and vagina in the female. Its 
shape, when distended, is ovoidal, or pyriform, the large end 
being below. When empty it is flattened against the pubes and 
is somewhat triangular. The direction of its long axis is down- 
ward and backward. The capacity of the bladder is very varia- 
ble, though, in health, the urine is voided when half a pint to 
one pint has been secreted. The upper third of the organ, 
about, is called the superior fundus, summit, or apex; its middle THE VISCERA. 
205 
third the body; the lower third the base, or fundus. The chan- 
nel through which the urine leaves the bladder is called the 
urethra, whose aperture is seen in the lower front portion. 
This part of the bladder is called the neck, and lies embedded 
in the prostate gland. In structure the bladder consists of 
the following coats: 1. The internal is mucous membrane. 
At the neck of the bladder there is a slight prominence, gen- 
erally absent, called the uvula vesicae, seen just at the commence- 
ment of the urethra. Between the uvula vesicae in front, as 
its apex, and the openings for the ureters, as its posterior 
angles, there is a triangular space called the trigonum vesicae, 
or triangle of the bladder, whose base is formed by a line drawn 
between the openings for the ureters, and whose sides are 
formed by a line on either side running from this point to the 
uvula and represented by a ridge in the mucous membrane made 
by a bundle of longitudinal fibres from the ureter. This space, 
by far the most sensitive part of the bladder, corresponds to a 
similar space on the exterior of the base. 2. The muscular 
coat is held to the mucous membrane by a layer of areolar tissue. 
It consists of longitudinal and circular fibres, the longitudinal 
forming two layers between which are found the circular. The 
circular fibres, at the neck of the bladder, are aggregated into 
a considerable mass, which, by their tonic contraction, keep 
the opening of the urethra closed. 3. The external coat is serous 
and incomplete. In the male it covers the summit, sides, pos- 
terior aspect, and posterior part of the base of the bladder, 
leaving uncovered the front and the front part of the base. 
The Urethra in the Male. 
The urethra is the last division of the canal which the urine 
transverses in seeking an outlet from the body. It commences 
at the neck of the bladder and terminates at the meatus urina- 
rius, its opening on the free extremity of the penis. Its length 
is variously estimated, owing to the varying length of the penis 
which it tunnels. It is divided into three portions, the prostatic, 
which begins at the neck of the bladder and pierces the prostate 
gland to appear at its apex and become the second, or mem- 206 
DESCRIPTIVE ANATOMY. 
branous portion, which passes on to enter the bulb of the corpus 
spongiosum and become the third, or spongy portion. The 
spongy portion continues through the corpus spongiosum to 
terminate at the meatus urinarius. It is the longest portion and 
the most variable in length. The length of the urethra as a 
whole is usually given as seven and a half inches, of which the 
prostatic portion occupies about one and one-fourth inches, 
the membranous three-fourths of an inch and the spongy por- 
tion the remainder. The prostatic portion is the largest. 
The Prostate Gland. 
This gland is a small horse chestnut-shaped body, found in 
the male, with its base against the neck of the bladder and its 
apex projecting forward. Its length is about one and one-fourth 
inches, its breath one and one-third, and its depth about one- 
half inch. It is invested by cellular tissue, has a proper fibrous 
capsule, and consists of interlacing unstriated muscular fibres, 
in the interstices of which are found the follicles of the gland, 
which secretes a milky fluid. It is divided into three lobes, 
two lateral and an inferior, or isthmus. Passing through it, 
nearer its upper than its lower surface, is the prostatic portion 
of the urethra. On the floor of this portion of the urethra is 
seen a prominence of the mucous membrane, about one-half an 
inch long, called the veru montanum. On either side of this 
prominence is a depression in the floor of the urethra, called 
the sinus prostaticus, in which are found some ten or fifteen 
apertures-the openings of the prostatic follicles; while in front 
of the veru montanum is a small saccular cavity, projecting 
backward, called the sinus pocularis, or utriculus prostaticus, 
or uterus masculinus. Opening on either side of the orifice 
of this sinus is seen a small aperture, the opening of the ejacu- 
latory ducts, which pass back, one on either side, to two lobu- 
lated oblong bodies, one on either side, just behind the prostate 
gland, and called seminal vesicles. THE VISCERA. 
207 
Seminal Vesicles. 
Each seminal vesicle is a reservoir for the seminal fluid, 
and is formed of a tube, about the size of a goose quill, five or 
six inches long, coiled into an oblong mass about two inches 
long, which lies on the lower surface of the base of the bladder, 
its large end projecting backward and outward from its fellow, 
the small end being in front just behind the prostate gland and 
approaching its fellow. The posterior extremities are about 
two inches apart, and a line drawn from one to the other is 
the base of a triangular space, whose apex is at the prostate 
gland, which may be designated the inter vesicular triangle. 
This space is devoid of peritoneum. The point where the peri- 
toneum strikes the base of the bladder corresponds to the pos- 
terior boundary of this triangle, whose sides are formed by 
the seminal vesicles with the vas deferens of either side lying 
internal to them. 
Vas Deferens. 
Commencing at the upper extremity of the testicle the VAS 
deferens forms one element of the spermatic cord, the others 
being blood vessels, nerves, etc., which ascends to the upper 
border of the pubes, where it plunges into the anterior abdominal 
wall, through the external abdominal ring, then outward, along 
the inguinal canal to the internal abdominal ring, where it turns 
backward through that ring to enter the abdominal cavity. As 
soon as the cord enters the abdomen its various constituents dis- 
perse. The vas deferens passes to the upper part of the side of the 
bladder, thence down its posterior surface, along the inner 
edge of the seminal vesicle, at the anterior extremity of which 
it is joined by the tube, whose convolutions form the seminal 
vesicle, and the two form the ejaculatory duct. 
The Ejaculatory Duct. 
The two ejaculatory DUCTS lie very near each other and pass 
forward and upward, through the substance of the prostate 
gland, for about three-quarters of an inch, to open on the sides 208 
DESCRIPTIVE ANATOMY. 
of the aperture of the sinus pocularis, which is found at the 
base of the veru montanum, in the floor of the prostatic portion 
of the urethra. 
The Penis. 
The penis consists of three cylinders, two, lying side by side, 
called the corpora cavernosa, and one in a groove between 
these known as the corpus spongiosum. When dissected out 
the corpus cavernosum are seen to commence by attachment 
to bone-the ischio-pubic ramus-by a portion called the crus, 
which terminates posteriorly in a pointed extremity; while an- 
teriorly it increases in size to become the corpus cavernosum. 
The corpora cavernosa do not extend to the extremity of the 
penis, but stop a little behind the meatus urinarius. The corpus 
spongiosum begins by a dilated portion called the bulb, situated 
between the crura, into which the membranous portion of the 
uretha passes to become the spongy portion. It then passes 
forward, tunnelled by the uretha, lying between the corpora 
cavernosa, until it reaches their anterior extremity, when it 
suddenly dilates into a considerable mass, which covers the 
extremity of the corpora cavernosa, and projects in a globular 
head beyond them. This dilated extremity is called the glans 
pens or head. The glans has its base backward, terminating 
in a rounded edge, raised above the surface of the corpora ca- 
vernosa, which is called the corona glandis, while the constricted 
portion behind it is called the neck. From the corona the glans 
slopes to its termination around the meatus urinarius. That 
portion of the penis extending from the crura, or rather where 
the three cylinders come in close relation, forward to the head, 
is called the body of the organ; and the two crura and the bulb 
constitute the root of the penis. 
Surrounding, and loosely adherent to, the body is a thin skin, 
which in front is formed into a fold, movable over the glans, 
and called the prepuce. On the lower aspect of the glans the 
prepuce is attached by a process, extending forward to the 
meatus urinarius. This attached portion is called the fraenum. 
Passing through the corpus spongiosum from the bulb behind 
to the meatus urinarius in front, is the spongy portion of the THE VISCERA. 
209 
uretha, which, just before its termination at the meatus, pre- 
sents a considerable dilation called the fossa navicularis. The 
mucous membrane lining the urethra presents many follicles, 
called lacunae, opening into the canal. When the mucous mem- 
brane reaches the meatus it is continued over the glans penis 
and the deep surface of the prepuce. 
The tissue of the three cylinders is that known as erectile 
tissue. Each cylinder is enveloped by a strong fibrous sheath, 
that of the corpus spongiosum being more delicate than . the 
others. Within this sheath the structure consists of interlac- 
ing bands of fibrous tissue, the interspaces between which con- 
tain dilated blood vessels, which when turgid with blood, pro- 
duce erection. The two corpora cavernosa, at the posterior 
part of the body of the organ, are separated some little distance 
from each other, but as they pass forward, come much closer 
together, for the fibrous tissue between them is thick posteriorly, 
whereas in front it is thin and presents numerous slit-like in- 
terruptions which have obtained for it the name of septum 
pectineiform. 
The Testicles. 
The testicles are a pair of small organs whose function it is 
to secrete the semen. They are found suspended by the sper- 
matic cord, in the bag called the scrotum, separated from each 
other, although lying side by side. Each testicle weighs from 
three-fourths to one ounce or more; it is an inch to an inch and 
a half long, about an inch antero-posteriorly, and half an inch 
transversely. It occupies the back of the scrotum, its position 
being from above downward and backward. 
The scrotum is thus constituted: 1. an external covering of 
skin; 2. beneath this a musculo-fibrous covering called the 
dartos; 3. lining the interior of the dartos, and also enveloping 
the testicle a serous membrane called the tunica vaginalis. That 
portion of the tunica vaginalis lining the dartos is called the 
parietal, and that lining the testicle the visceral layer. 
There are two cavities in the scrotum separated by a septum 
from the dartos called septum scroti. There is a tunica vaginalis 
for each testicle. 210 
DESCRIPTIVE ANATOMY. 
Structure of the Testicles. 
When the visceral layer of the tunica vaginalis is removed 
we find beneath a blush white fibrous investment of the testicle 
called the tunica albuginea. This is much thickened at the back 
part, where it is called the mediastinum. 
Lining the inner aspect of the tunica albuginea is a reddish 
vascular investment called the tunica vasculosa. Lying on the 
posterior aspect of the testis is a flattened body called the epi- 
didymis, which is made up of the convolutions of the tube 
conveying away the semen. The upper portion of the epididy- 
mis is alone permanently connected with the testicle, for it is 
here that the ducts, which transmit the semen from the testes, 
emerge and unite to form the epididymis. The upper portion 
of the epididymis is called the globus major, the lower portion, 
which terminates in the vas deferens, the globus minor. The 
intermediate portion is called the body. The semen is secreted 
in what are called the lobules of the testicles, which number 
from 250 to 400, each lobule being separated from those adja- 
cent by septa sent in from the tunica albuginea, which septa, 
however, are covered on both sides by a layer from the tunica 
vasculosa. 
Each lobule consists of the convolutions of a small tube some 
one two-hundredths of an inch in diameter, arranged from 
before backward with the large end of the convoluted mass in 
front and the small end behind at the mediastinum, where 
many lobules unite to form a single duct, which from its com- 
paratively straight course, is called the rectum. In the testis 
there are from 20 to 25 vasa recta, which plunge into the 
mediastinum and there unite to form from two to twelve ducts, 
which, ascending through the mediastinum in a sinuous course, 
are called collectively the rete testis. When the ducts reach the 
upper extremity of the mediastinum, they terminate in from 
nine to thirty other ducts, called vasa-efferentia, each of which 
is thrown into convolutions assuming a conical appearance 
which are known as coni vasculosi and form the globus major. 
The bases of the cones terminate in large ducts which unite in 
the body of the epididymus into one duct whose convolutions, ORGANS OF GENERATION IN THE FEMALE. 
211 
some twenty feet long, form the body and globus minor of the 
epididymis and then become the vas deferens. 
The continuous course of the semen is then, lobule, which 
may be composed of as many as three tubes, vasa recta, rete 
testes, vasa efferentia, coni vasculosi, epididymis, body and 
globus minor, vas deferens. 
ORGANS OF GENERATION IN THE FEMALE. 
The organs OF generation in the female are divided into 
those within and those external to the pelvic cavity. The ex- 
ternal organs, vulva, clitoris, &c., occupy the perineal space. 
The boundaries of the outlet of the pelvis are the same in both 
male and female subjects, but the ischio-rectal region is wider 
and longer in the female. In the mid-line are seen the open- 
ing of the vagina and the anus separated by a mass of tissue 
about one inch thick called the perineal body. The external or- 
gans consist of two labia majora surrounding the aperture of 
the vagina, composed externally of skin, which is covered with 
hairs, and internally of mucous membrane, and united both in 
front and behind. Internal to these are two thinner projecting 
folds, one on each side, called labia minora, which enclose in 
front a projecting body, the clitoris. Between the clitoris and 
the mouth of the vagina is a space about one inch long, called 
the vestibule, at the hinder part of which, near the mouth of 
the vagina, is an opening, the meatus urinarius. 
The pelvic organs consist of an egg producing body-the 
ovary-and a channel to convey the egg to the exterior. Part 
of this channel is modified to perform the function of hatching 
-the uterus-and another part, that of copulation-the 
vagina. 
The uterus consists of an upper part, or fundus, a middle 
portion, or body, and a lower part, or cervix or neck. The 
vagina is a short, bent canal which serves the double function 
of conveying the semen to the uterus, and of conducting the 
foetus to the external world. The relations which the uterus 
and its so-called appendages bear to neighboring structures 212 
DESCRIPTIVE ANATOMY. 
constitutes the remainder of the study of the female generative 
organs. 
The peritoneum passes over the brim of the pelvis, envelop- 
ing the first portion of the rectum completely, and covering 
the upper one inch of the second portion in front, as in the 
male. From the front of the rectum it passes to the posterior 
wall of the vagina, which it covers for its upper one inch or 
inch and a half; passes to the back of the uterus and mounts 
upon it to its top, where it spreads out upon either side to 
envelop the appendages of the uterus; descends upon the front 
of the uterus, covering all of the front except that part con- 
tained within the vagina, and thence passes to the bladder, 
which is covered, as in the male, for its posterior half, the 
peritoneum leaping from the top of the bladder to the posterior 
surface of the anterior abdominal wall, forming the false liga- 
ments of the bladder as in the male. That fold of peritoneum 
which extends transversely outward from the top of the uterus, 
enveloping the appendages of that organ in a double-layered 
fold which forms a vertical septum extending transversely 
across the pelvic cavity and striking the lateral pelvic walls a 
little behind their middle, is known as the broad ligament of 
the uterus. The folds of peritoneum between the uterus and 
vagina and rectum posteriorly and the uterus and bladder an- 
teriorly are known as the posterior and anterior ligaments of 
the uterus respectively, divided by the mid-line into two anterior 
and two posterior. Another ligament, a round cord, extends, 
in the folds of the broad ligament, from the lateral aspect of 
the uterus to the internal abdominal ring, to follow the inguinal 
canal and be finally lost in the labium ma jus, under the name 
of the round ligament. The depression between the vagina and 
the uterus in front and the rectum behind is known as the 
pouch of Douglas, the posterior ligaments bounding it on either 
side. 
The broad ligament ericloses between its folds the round liga- 
ment, the fallopian tube, the ligament of the ovary, and the 
ovary. The fallopian tubes occupy the highest part of the 
broad ligament, extending outward from the upper angle of 
the uterus to become closely connected with the ovary. They ORGANS OF GENERATION IN THE FEMALE. 
213 
enlarge as they pass outward and form at the extremity a 
trumpet-shaped mouth, fringed by diverging processes or fim- 
briae, one of which is attached to the ovary. The tube is tor- 
tuous through the greater part of its course and when stretched 
out is about five inches long. A little behind and below the 
fallopian tube is a small round cord, the ligament of the ovary, 
which attaches the ovary to the upper part of the side of the 
uterius. 
The ovary is about one and a half inches long, one inch wide, 
and half an inch thick. One end looks toward the uterus, one 
end outward, one surface upward and forward, the other down- 
ward and backward. It is completely invested by peritoneum, 
bulging the posterior folds of the broad ligament and appearing 
not to be in contact with the anterior fold. It is held to the 
uterus by its ligaments and the ova formed by it are conducted 
to the uterus by the fallopian tube. 
The lower end of the uterus projects into the vagina, which 
thus surrounds the neck of the uterus, cutting off the lower 
portion of that organ from relation with surrounding viscera. 
The vagina extends higher up on the uterus posteriorly than 
anteriorly. 
The rectum is about the same length as in the male, and is 
divided into three portions for study. Its lateral and posterior 
relations are the same as in the male, while the anterior rela- 
tions are different. The first part of the rectum has in front 
of it the uterus, separated from it by convolutions of the small 
intestine. The upper inch of the second portion, that part 
covered by peritoneum in front, is separated, by convolutions 
of the small intestine, from the posterior wall of the vagina, 
which in turn cuts it off from the neck of the uterus. The re- 
mainder of the second portion is at first adherent to the pos- 
terior wall of the vagina, but lower down it passes downward 
and backward, diverging from the vagina, the interval between 
the two being filled by a triangular mass of connective tissue 
forming the perineal body and corresponding to the tissue be- 
tween the bulb of the corpus spongiosum and the rectum in the 
male. The ureter bears the same relation to the rectum as in 214 
DESCRIPTIVE ANATOMY. 
the male, and lies upon the side of the vagina, which cuts it 
off from relation with the neck of the uterus. 
The female bladder occupies the same position as in the 
male, lying behind the symphysis pubis and bearing the same 
relation to the peritoneum. The anterior and lateral relations 
are also the same, except that there is no vas deferens, the 
position of this structure being in part occupied by the round 
ligament, which lies above and internal to the external iliac 
artery. The posterior surface of the bladder is separated from 
the anterior wall of the uterus by some convolutions of the 
small intestine. The base of the bladder looks more nearly 
downward than in the male, and rests for its anterior three- 
fourths upon the anterior wall of the vagina, to which it is 
firmly adherent, its posterior one-fourth being covered by peri- 
toneum. The uretha is nearly straight, but has a slight curve 
downward. It lies on the anterior wall of the vagina, is about 
two inches long, runs through an opening in the triangular liga- 
ment about one inch below the symphysis pubis, is surrounded 
by muscular fibres forming what is called the compressor ure- 
thrae, and terminates in the vestibule at the meatus urinarius. 
The vagina is the canal of communication between the uterus 
and the vulva. It is directed obliquely downward and forward, 
corresponding to the axis of the outlet of the pelvis, while the 
uterus corresponds to the axis of the brim, the two thus form- 
ing a curve whose concavity is forward. It is compressed, so 
that its anterior and posterior walls are in contact. Its anterior 
wall is about two and a half inches in length, its posterior about 
three and a half. It is parly closed in the virgin by the hymen. 
The relations of the vagina have been given in connection 
with other structures. 
The JErial Apparatus. 
The air reaches the lungs from the throat through a tube 
which has received different names in its various parts. It is 
first called the larnyx, then the trachea, which, opposite the 
fifth dorsal vertebra, divides into the two bronchi. THE VISCERA. 
215 
The Larynx. 
The larynx is formed upon a framework of separate 
cartilages which require to be studied under individual names. 
These cartilages are as follows: 
Thyroid 
Cricoid 
Two Arytenoid 
Epiglottis 
Two Cornicula Laryngis 
Two Cuneiform. 
Thyroid Cartilage. 
The thyroid (cartilage thyroidea) is the upper, the front and 
the largest cartilage of the larnyx. In front it comes to an 
acute angle and produces the prominence, called the Adam's 
apple, pomum Adami. From this acute, or receding angle, it 
passes backward and outward on either side in a quadrilateral 
plate called the ala of the thyroid cartilage. Each ala presents 
an internal and external surface, superior, inferior, and pos- 
terior border. 
The outer surface is slightly concave from above downward, 
wider above than below and marked by an oblique ridge, run- 
ning from above downward and forward, terminating at each 
end in a prominence, or tubercle. 
The internal surface is nearly flat, slopes outward and back- 
ward from the receding angle, and is slightly roughened for 
muscular attachment. 
The superior border is sinuous in outline. It commences in 
the notch found marking the upper end of the angle, slopes first 
upward and slightly backward, then runs nearly backward to 
terminate in a prominent projection called the superior cornu. 
Just before reaching the superior cornu it is marked by a 
slight depression. This border is rounded and smooth. 
The inferior border is also sinuous, shorter than the superior, 
like it, round and smooth, and terminates in the inferior cornu. 
The posterior border is rounded and free, and prolonged both 
above and below into processes called the superior and inferior 216 
DESCRIPTIVE ANATOMY. 
cornua, each terminated by a tubercle. The superior cornu is 
the longest. 
The inferior cornu projects downward from the posterior 
border. It is much shorter and thicker than the superior, and 
is marked on its inner face by a round, flat articular facet for 
a similar surface on the cricoid cartilage. 
Cricoid Cartilage. 
The cricoid cartilage (cartilago cricoidea) is a ring and lies 
supporting the thyroid, between whose inferior cornua it is 
grasped. It is narrow in front-not more than one-fourth of 
an inch deep-but a full inch in depth behind. It presents an 
upper and a lower border, but, being a ring, surfaces are not 
ascribed to it. The front portion of its exterior is marked on 
the mid-line by a slight ridge, on each side of which is a small 
impression for muscular attachment. Behind there is a similar 
ridge in the middle with well marked muscular impressions on 
either side. In front of these impressions, and on the lateral 
aspect, a small, round, flat articular facet is seen on either side 
intended for the facets on the inferior cornua of the thyroid. 
Its upper border slopes upward and backward, presenting 
in the centre, behind, a slight notch, and on either side of 
this a concavo-convex articular facet, on which is perched 
another cartilage, the arytenoid. The anterior portion of this 
border is smooth and rounded for ligamentous attachment. 
The inferior border is nearly straight, thick and rounded 
and sometimes marked by a deep notch. It is held by liga- 
ments to the first ring of the trachea. 
The interior of the ring is smooth and covered by mucous 
membrane. 
Arytenoid Cartilages. 
The arytenoid cartilages (cartilagines arytenoidese) are 
found upon the cricoid, between the wings of the thyroid, oc- 
cupying the articular facets on its upper border. It is trian- 
gular in shape, base below and apex above, and is divided into 
three surfaces, posterior, anterior and internal; three borders. THE VISCERA. 
217 
external and two internal; and two angles, anterior and ex- 
ternal. 
The 'posterior face is concave for muscular attachment; the 
anterior is rough while the internal is smooth and flat and faces 
its fellow of the opposite side. 
The two internal borders are inconspicuous, forming the an- 
terior and posterior boundaries of the inner face. 
The external border is rough and slopes upward, inward and 
backward. 
The external angle points outward and backward and is 
rough and thick. It is called the muscular process. 
The anterior angle, thinner and longer, is known as the vocal 
process. 
The apex points upward and inward and is surmounted by 
a small cartilage, the comicula laryngis. 
The base, directed downward, is concavo-convex for articu- 
lation with the similar facet on the upper border of the cricoid. 
The comicula laryngis are two small cartilages found 
perched upon the apex of the arytenoids. The cuneiform are 
small masses found in the aryteno-epiglottidean fold. 
Epiglottis. 
The epiglottis (cartilago epiglottica) lies just above the re- 
ceding angle of the thyroid cartilage. It is leaf-shaped, its 
apex downward and forward and its base, which presents a 
slight notch, upward and backward and lying at the base of 
the tongue. Its upper end may be sometimes seen by looking 
down the throat. 
It is covered by mucous membrane which holds it to sur- 
rounding structures and, when this is stripped off, is seen to 
present a convex anterior and a concave posterior surface, the 
latter marked by depressions for small glands. 
Ligaments of the Larynx. 
The cartilages of the larynx are held together by ligaments, 
some of which, like ligaments at other articulations, serve only 218 
DESCRIPTIVE ANATOMY. 
the purposes of such fibres; while other so-called ligaments 
are specialized bands employed in producing sound. 
The hyoid bone lies just above the superior border of the 
thyroid cartilage, and passing between them, is an unbroken 
membrane called the thyro-hyoidean, and in each of the pos- 
terior edges of this membrane a rounded cord, which passes 
from the superior cornua of the thyroid cartilage to the pos- 
terior extremity of the hyoid bone, called lateral thyro-hyoid 
ligament. 
The thyro-hyoid membrane is a thin sheet of fibrous tissue 
which is attached below to the upper border of the thyroid 
cartilage, extending from one cornu to the other and filling in 
the notch above the angle. Above, it passes beyond the lower 
border of the hyoid and is attached to the upper border and 
posterior surface of the body of that bone, extending on either 
side to the cornua. Between the membrane and the posterior 
surface of the body of the hyoid there is a pouch-like space left. 
The thyroid and cricoid cartilages are held together by the 
following ligaments. The extremity of each inferior cornu of 
the thyroid cartilage is held to the facet on the side of the 
cricoid by a capsular ligament. The considerable interval which 
exists in front between the lower border of the thyroid and 
upper border of the cricoid is closed in by a fan-shaped yellow 
elastic membrane, called the crico-thyroid membrane, which is 
attached below to the upper border of the cricoid and above to 
the lower border of the thyroid for about one-fourth of an inch 
on each side of the middle line and then presents a free edge, 
covered by mucous membrane, which posteriorly is attached 
to the anterior angle of the base of the arytenoid cartilage, 
forming the lower, or true vocal chords. 
When viewed from above the vocal chords appear to be sepa- 
rate bands of elastic fibres, each arising from the receding angle 
of the thyroid and passing backward, diverging from its fel- 
low, to be attached to the vocal process of the arytenoid. They 
are called inferior thyro-arytenoid ligaments, or true vocal 
chords. 
Each arytenoid is bound to the cricoid by a capsular ligament 
which holds the cartilages together, forming a concavo-convex THE VISCERA. 
219 
articulation lined by a synovial sac. In addition to the inferior 
thyro-arytenoid ligaments, mentioned above, another pair, the 
superior thyro-arytenoid, or false vocal chords, extend from 
just above the base of the arytenoid to the receding angle of 
the thyroid. 
Passing now to the epiglottis we find its apex held to the re- 
ceding angle of the thyroid by a narrow ligament called thyro- 
epiglottic. It is connected to the hyoid bone by a ligament 
called hyo-epiglottic, which is attached to the epiglottis on its 
front edge near its apex. The back of the tongue and the epig- 
lottis are connected by three ligaments, one in the centre and 
one on each side, called glosso-epiglottic, middle and lateral. 
Muscles of the Larynx. 
The movements on each other of the separate cartilages which 
constitute the larynx are mainly effected by five pairs of small 
muscles called the intrinsic muscles of the larynx. 
Crico-thyroid 
Posterior Crico-arytenoid 
Arytenoid 
Thyro-arytenoid. 
Lateral Crico-arytenoid 
Crico-Thyroid. 
The crico-thyroid is a small triangular muscle lying on the 
side of the cricoid cartilage and partly covering the crico-thy- 
roid membrane, which appears on the mid-line in the interval 
between the two muscles. 
It arises from the front and side of the cricoid cartilage and, 
passing upward, backward and outward, is inserted into the 
lower border of the thyroid cartilage from the median line in 
front to the inferior cornu. 
Action-When the thyroid cartilage is fixed by the thyro- 
hyoid muscle, the crico-thyroid will draw up the front of the 
cricoid, depressing the back which carries the arytenoid with 
it, thus elongating and rendering tense the vocal chords. 220 
descriptive anatomy. 
Posterior Crico-Arytenoid. 
The posterior crico-arytenoid arises from the depression on 
the posterior aspect of the cricoid cartilage and, passing up- 
ward, outward and forward, is inserted into the outer angle 
of the base of the arytenoid. 
Action-By drawing on the muscular process, or outer angle 
of the arytenoid, it rotates that cartilage around a vertical axis, 
carrying the vocal processes away from each other, widening 
the glottis and, to some extent, tightening the chords. 
Lateral Crico-Arytenoid. 
The lateral crico-arytenoid arises from the side of the 
cricoid cartilage, and, passing upward, outward and backward, 
is inserted into the outer angle of the base of the arytenoid. 
Action-It is the antagonist of the posterior crico-arytenoid, 
drawing the outer angle of the arytenoid forward, approximat- 
ing the vocal process and rendering the vocal chords loose. 
Arytenoid. 
The arytenoid is a single muscle which arises from the con- 
cave posterior face of one arytenoid cartilage and passes trans- 
versely across the interval between the two to be inserted into 
the same part of the opposite cartilage. Some of the fibres 
which arise from the base of one cartilage are inserted into 
the apex of the other, while others cross the interval horizon- 
tally. This arrangement renders approximation of the ary- 
tenoid cartilages more exact. 
Action-By drawing the arytenoid cartilages towards each 
other, it narrows the glottis. 
Thyro-Arytenoid. 
The thyro-arytenoid arises from the receding angle of the 
thyroid cartilage just beside and external to the attachment of 
the vocal chords, and, passing backward, parallel with the THE VISCERA. 
221 
vocal cord, is inserted into the anterior angle of the base of 
the arytenoid cartilage. This muscle runs parallel with the 
true vocal chords, into which some of its fibres are inserted. 
Action-By drawing the muscular process forward, turning 
the vocal process inward and forward, it narrows the glottis 
and relaxes the vocal chord. Those fibres inserted into the vocal 
chord, change the tension of the chord at different points. 
Vessels and Nerves. The superior and inferior thyroid 
arteries supply these muscles. The superior laryngeal nerve 
supplies the crico-thyroid. The inferior, or recurrent laryngeal 
supplies the other muscles. 
The larynx is lined by mucous membrane continuous with 
that of the mouth. Looking into the cavity of the larynx from 
below, at a certain point, the cavity is suddenly narrowed by 
two ridges, one on either side, running from before, where they 
are close together, backward, diverging as they go and leaving 
a triangular interval between them called the chink of the glot- 
tis or rima glottidis; these ridges are produced by the inferior 
thyro-arytenoid ligaments, or true vocal chords. Reversing the 
larynx and looking into its cavity from above, the opening into 
it from the pharynx is seen to be limited by the epiglottis which 
projects upward and backward. Over the opening, posteriorly, 
are seen the arytenoid cartilages; laterally are folds of mucous 
membrane, the ventricular bands; the opening is heart-shaped 
with its broad end in front. Down in the cavity are seen the 
ridges on each side, one above the other. The lower pair are 
those seen from below, the upper correspond to the superior 
thyro-arytenoid ligaments and are the false vocal chords. As 
they are much less prominent than the true chords, they can- 
not be seen when the cavity is viewed from below. The space 
between the false vocal chords bears no name, but the similar 
and smaller space between the true chords is known as the rima 
glottidis. On each side of the glottis is another space formed 
by a recess in the walls of the larynx, between the true and 
the false vocal chords, which is called the ventricle of the 
larynx, and this space is continued up on the outside of the 
false vocal chords, between it and the wall of the larynx for 222 
DESCRIPTIVE ANATOMY. 
some distance. This prolongation of the cavity is known as 
the sacculus laryngis. 
It will be seen, therefore, that the larynx is divisible into 
three portions by the position of the vocal chords, the upper 
portion presenting the epiglottis, the folds of mucous mem- 
brane extending between the arytenoid and the epiglottis and 
containing the pyriform sacculus laryngis which runs up just 
internal to its outer wall. This space extends to the superior 
thyro-arytenoid membrane. 
The second subdivision is the space between the vocal chords 
and contains four openings, viz., one above, leading from the 
upper to the middle compartment,-being the space between 
the false chords and sometimes called the false glottis;-one be- 
low, the space between the true chords, called the glottis, and 
leading into the lower compartment; and one on either side, 
being the opening into each laryngeal pouch. The glottis is 
the triangular space found between the true vocal chords in 
front and between the two arytenoid cartilages behind. 
The lower compartment is simply the circular space enclosed 
by the cricoid cartilage, and would, therefore, be the means of 
establishing communication between the larynx, above, and the 
trachea, below. 
Trachea. 
Succeeding the larynx conies the second subdivision of the 
air-tube known as the trachea. Commencing where the larynx 
terminates opposite the fifth cervical vertebra, it descends in 
front of the vertebral column, from which it is separated by 
the oesophagus, and terminates by dividing, opposite the fifth 
dorsal vertebra, into the right and left bronchi. It is a cylin- 
drical tube flattened on its posterior aspect, about four and a 
half inches long and one inch in diameter. In the female these 
dimensions are somewhat less. Its appearance, when viewed 
from the front, is annulose, due to the fact that its largest ele- 
ment is a number-fifteen to twenty-of cartilaginous rings, 
one lying above the other. 
The flattening posteriorily is due to the fact that each ring 
is wanting in its posterior third, thus leaving this portion of THE VISCERA. 
223 
the tracheal wall wanting in cartilage. The rings are not in 
contact, but are separated, and at the same time maintained in 
position by a fibro-elastic membrane, which covers both sur- 
faces of the rings, for they, in fact, lie embedded in the sub- 
stance of the membrane. Between the posterior extremities of 
the rings, over the interval left by their imperfection, the mem- 
brane is continued and is here strengthened by unstriated mus- 
cular fibres, both longitudinal and transverse. The longitudinal 
are unimportant; but the transverse, passing between the pos- 
terior extremities of the rings, can, by their contraction, 
diminish the diameter of the trachlea. 
The interior of the trachea is lined by mucous membrane, 
continuous with that of the larynx above and prolonged below 
into the bronchi, bronchial tubes and ultimate air cells of the 
lungs. Beneath the mucous membrane, between it and the 
fibro-elastic membrane, is a yellow elastic membrane which is 
much more distinct posteriorly, where the fibres which com- 
pose it are gathered into longitudinal bundles. To sum up its 
structure we say the trachea is lined by mucous membrane, be- 
neath this yellow elastic fibres, external to this a yellow fibro- 
elastic membrane lying in which are the rings of the trachea. 
Besides these there are transverse muscular fibres between 
the posterior extremities of the rings, and scattered around the 
tube some unimportant longitudinal fibres. 
Bronchi. 
Taking up the air tube again, we find that the trachea, or 
wind pipe, when it has reached a point corresponding to the 
front of the fifth dorsal vertebra forks, the prongs of the fork 
being known as the bronchi, right and left. Each bronchus ex- 
tends from its origin to the inner surface of the lung, form- 
ing one element of the root of the lung. The two bronchi are 
not similar and the difference between them may be thus stated: 
The right is shorter, larger and more nearly horizontal, com- 
ing off nearly at right angles to the trachea, whereas the left 
has a considerable obliquity downward. If the trachea be cut 
across near its termination and the cavity examined, a slight 224 
DESCRIPTIVE ANATOMY. 
antero-posterior ridge is found separating the two bronchi. 
This ridge lies nearer the left than the right side and in conse- 
quence a foreign body falling into the trachea is more likely to 
enter the right than the left bronchus. The left bronchus is 
about two inches long, the right about an inch. In structure 
they exactly resemble the trachea. 
Lungs. 
The LUNGS are a pair of organs found in the thoracic cavity, 
one on each side of the middle line, resting upon the diaphragm 
below and having the heart, enclosed in the pericardium, lying 
between them. Each lung is conical in shape, with its base be- 
low, resting on the upper surface of the diaphragm and concave 
in shape to correspond with that surface. The apex is above, 
and extends about one and one-half inches into the root of 
the neck. Besides the base and apex, each lung presents the 
following subdivisions: the posterior border, long, thick, and 
rounded, contrasting strongly with the anterior, which is thin, 
short and sharp. The outer surface is convex to correspond 
with the concave inner face of the chest wall. The inner face, 
which looks towards its fellow, is marked by a concavity which 
is caused by the heart, in the pericardium, which lies between 
the two lungs. The inner surface of the left lung is much more 
concave than that of the right, owing to the inclination of the 
heart to the left. A little above and posterior to the centre of 
each lung on its inner face the root is seen to enter its sub- 
stance. The root is made up of various elements, nerves, lym- 
phatic, etc., but its chief constituents are the bronchus, pul- 
monary artery and two pulmonary veins. From behind for- 
ward, the relation which these structures bear to one another 
is the same for both lungs, viz: bronchus, artery, vein: but 
from above downward the relation is different, in the two 
lungs. In the right it is bronchus, artery, vein: in the left, 
artery, bronchus, vein. The veins, on both sides are the lowest, 
and the difference is caused by a change in the relation of the 
artery and bronchus in the left lung which is accounted for THE VISCERA. 
225 
by the downward inclination and greater length of the left 
bronchus. 
Each lung is divided by fissures into lobes, the right into 
three and the left into two. Commencing about three inches 
from the apex, on the posterior border of each lung, an oblique 
fissure passes through the lung downward and forward to near 
the lower extremity of the anterior border. In the right lung 
there is another fissure which begins near the centre of the 
oblique fissure and runs nearly horizontally forward to the 
anterior border, thus dividing the right lung into three lobes 
known as upper, middle and lower. In the left lung there are 
but two lobes, upper and lower. The right lung is slightly 
larger than the left, owing to the encroachment of the heart 
on the left lung. The right, however, is shortened by the 
right lobe of the liver, which bulges the diaphragm on that 
side, and the difference is in reality not great-the right lung 
weighing about twenty-two and the left twenty ounces. 
The Pleurae. 
Enveloping each lung, and lining the chest wall is a serous 
membrane, one on each side. 
These two membranes are the two pleurae. They are sepa- 
rate from each other and each forms a distinct closed sac for 
its lung, one face of the sac lining the inner surface of the chest 
wall, while the other completely invests the lung. In front, 
behind the sternum, the two pleurae approach each other closely, 
and are sometimes in contact about the centre of the sternum. 
In tracing the reflections of the pleura, as it is a closed sac, 
we can begin at any point, and, following it around, will 
return to that point. Beginning on the root of the lung we 
trace first the visceral layer, or pleura pulmonalis, and 
then the parietal layer, or pleura costalis, the two being con- 
tinuous. From the front of the root, the pleura passes for- 
ward on the inner face to the anterior border of the lung, then 
around the convex outer surface to the posterior border, and 
then forward on the inner face to the back of the root of the 
lung and then to the side of the vertebral column, where it be- 226 
DESCRIPTIVE ANATOMY. 
comes the parietal layer, which passes thence along the inner 
surface of the chest wall to the sternum in front, where it 
leaves the chest wall and passes backward on the pericardium 
to the front of the root of the lung to become continuous with 
the visceral layer which we have just traced. The free sur- 
faces of the two layers secrete a small amount of liquid which 
renders the movements of the lungs i-n respiration easy. 
The Mediastinum. 
Between the opposing surfaces of the pleurae and the ster- 
num in front and vertebral column behind, there is a space, 
called the mediastinum. 
This space is of very irregular shape, varying in size at 
different points. It is conveniently divided into the superior, 
anterior, middle and posterior. 
The superior mediastinum extends from sternum to vertebral 
column, and is all that portion which lies above the level of 
the pericardium, its lower boundary being a plane extended 
from the junction of the manubrium and gladiolus in front to 
the lower border of the fourth dorsal vertebra behind. On 
either side would be the pleurae, containing the lungs. In this 
space lie the great vessels springing from the heart and the 
aorta and the structures passing from the neck into the thorax. 
The anterior mediastinum is bounded in front by the sternum 
and lower costal cartilages of the true ribs, behind by the 
pericardium, and on either side by the pleura. It is oblique 
in direction from above downward and to the left, and is larger 
below than above. 
The middle mediastinum is the broadest part of the inter- 
pleural space. Above it is limited by the plane from the junc- 
tion of the manubrium and gladiolus to the lower border of the 
fourth dorsal vertebra; below is the diaphragm; laterally the 
pleurae; while behind and in front the pericardium marks the 
separation between it and the posterior and anterior medias- 
tinal cavities. In this space are the heart, a part of the superior 
vena cava and azygos major vein, the pulmonary artery and THE VISCERA. 
227 
veins, and the bifurcation of the trachea with the bronchi. 
The phrenic nerves are in the space on the pericardium. 
The posterior mediastinum is irregularly triangular, being 
bounded in front by the pericardium and roots of the lungs, 
behind by the vertebral column, and laterally by the pleurae. 
It extends from the fourth dorsal vertebra downward, and 
contains the descending aorta, oesophagus, and pneumogastric 
nerves, thoracic duct, azygos veins, and splanchnic nerves. 
The Heart. 
The heart is a hollow muscular organ found in the cavity 
of the chest, lying between and almost surrounded by the two 
lungs; it rests upon the convex upper surface of the diaphragm, 
and is contained in the middle mediastinum. It is contained 
in a closed cavity, formed by the pericardium, lying, for the 
greater part of its extent, unattached; but, since its function 
is the maintenance of the circulation of the blood, the vessels 
which bring this to or carry it from the heart all communicate 
with its upper part or base, and thus maintain it in position. 
To render its movements free in the pericardium, that structure 
is lined by a serous membrane, which, like all others, is a 
closed sac, one layer lining the pericardium and the other cov- 
ering the heart from the origin of the vessels on one side to the 
same point on the opposite side. The portion lining the peri- 
cardium is called the serous pericardium, and the membrane 
which it lines the fibrous pericardium. The heart is conical 
in shape, its base being above and to the right and its apex 
below and to the left. It is about five inches long, three and 
a half inches transversely, and two and a half antero-pos- 
teriorly. Its weight is from nine to twelve ounces, varying 
in the two sexes and being slightly larger in the male. 
The exact position of the heart is thus stated: The base 
lies behind the sternum, is directed backward, upward and to 
the right opposite the sixth, seventh and eighth dorsal verte- 
brae, from which it is separated by the right pulmonary vein, 
oesophagus trachea and aorta. It is formed by the auricles 
(atria), mainly by the left. It is limited below by the coronary 228 
DESCRIPTIVE ANATOMY. 
sulcus. The apex, formed by the left ventricle, is downward 
and to the left, striking the chest wall at the space between 
the fifth and sixth ribs, three and one-half inches to the left 
of the middle line, about opposite the gladio-xiphoid joint. 
The anterior surface (fascies sterno-costalis), directed for- 
ward and to the left, is formed chiefly by the right ventricle, 
but has the anterior inter-ventricular groove near its left. 
The posterior inferior surface (fascies diaphragmatica), 
looks downward and backward, is marked by the posterior in- 
ter ventricular furrow, and is made up by the ventricles, chiefly 
the left. 
The right border (margo acutus), formed mainly by the 
right auricle and ventricle, is nearly vertical above and lies 
behind the third, fourth and fifth cartilages about half an inch 
from the edge of the sternum. The ventricular part is nearly 
horizontal and extends from the sternal end of the sixth car- 
tilage to the apex of the heart. 
The left border (margo obtusus) is formed by the left ven- 
tricle mainly and extends from the second left intercostal space 
4.5 C. M. from the mid-line downward to the apex (Gray). 
The cavity of the heart is separated into a venous and an 
arterial half, or apartment, by an obliquely vertical septum, 
which cuts off all communication between the halves. The 
position of the septum can be predicted by an inspection of 
the exterior of the heart, for it is marked by a groove passing 
from the base anteriorly and to the left downward to the right 
of the apex to run along the posterior aspect of the heart and 
terminate at the base, towards its right aspect. An artery is 
found lying in this groove, which is called inter-ventricular. 
From the position of the groove it is seen that the apex of the 
heart is formed entirely by the left half, the front of the heart 
mainly by the right half, while the back is the product, prin- 
cipally, of the left half. 
When the heart is laid open its entire cavity is seen to' be 
lined by a serous membrane, called .the endocardium, continued 
into the vessels which communicate with it; and each lateral 
half is subdivided by a partial horizontal septum into two 
cavities, the upper called the auricle, right or venous, and left, THE VISCERA. 
229 
or arterial, the lower, the ventricle, right, or venous and left, 
or arterial. The position of the horizontal septum is indicated 
by a groove passing around the heart, called the auriculo-ven- 
tricular. 
In the adult the venous blood of the entire body, with the 
exception of that of the heart itself, is returned into the venous 
auricle by two great veins, called venae cavae, superior and in- 
ferior, the one bringing the blood from the head and upper 
extremities, the other from the lower extremities and body. 
The venous blood from the heart is returned to the venous 
auricle by a separate vein, called the coronary, which, just as 
it is about to enter the auricle, dilates into what is known as 
the coronary sinus. Besides these channels for the return of 
the venous blood, there exist numerous minute apertures in 
every cavity of the heart through which its venous blood may 
enter to a small extent. These are called foramina Thebesii. 
The venous blood thus collected by the venous auricle is driven 
by its pulsation into the venous ventricle, with which it com- 
municates by an aperture through the horizontal septum, called 
he venous auriculo-ventricular opening. From the venous ven- 
tricle the blood is sent into the pulmonary artery, which soon 
divides into a branch to each lung. 
Taking up the appearances seen in the cavities of the heart, 
we begin with the venous auricle. 
The auricle (B N A) means the auricular appendix only. 
The venous auricle (atrium dextrum) consists of two por- 
tions; the larger part is called the sinus, but, communicating 
with this and projecting forward, is an ear-shaped addition, 
called the appendix auriculae-hence the name of the auricles. 
The sinus of the venous auricle presents the following objects: 
At its upper back part, the opening of the superior vena cava; 
at the lower back part, the opening of the inferior vena cava; 
between the two openings a slight thickening of the auricular 
wall called the tubercle of Lower; between the opening for 
the inferior vena cava and the auriculo-ventricular opening is 
the opening for the coronary sinus, guarded by a valve-like 
fold of endocardium, called the coronary valve; on the septum 
between the two auricles, an oval depression, called the fossa DESCRIPTIVE ANATOMY. 
230 
ovalis, and surrounding this, except below, a ridge called an- 
nulus ovalis; extending along the wall of the auricle from the 
opening of the inferior vena cava to the fossa ovalis, is a ridge, 
the remains of the Eustachian valve of the foetus; the lining 
membrane presents ridges caused by little muscular columns 
called musculi pectinati; the opening through the horizontal 
septum into the venous ventricle; and, lastly, foramina Thebesii. 
To sum up we have the following: 1, superior vena cava; 
2, inferior vena cava; 3, coronary sinus; 4, foramina Thebesii; 
5, venous auriculo-ventricular opening, and six other appear- 
ances, viz., 1, musculi pectinati; 2, tubercle of Lower; 3, coro- 
nary valve; 4, Eustachian valve; 5, fossa ovalis; 6, annulus 
ovalis. 
The venous ventricle (ventriculus dexter) has two openings 
communicating with it, one for the pulmonary artery and the 
other from the venous auricle. The venous auriculo-ventricular 
opening is surrounded by an oval, fibrous ring to which the 
segments of the valve are attached. To prevent regurgitation 
of blood when the ventricle contracts, the opening is guarded 
by a valve consisting of three flaps, formed of folds of endo- 
cardium strengthened by fibrous tissue and some muscular 
fibres, which are triangular in shape with the base attached to 
the fibrous ring and the apex free. When the ventricle con- 
tracts, the blood insinuates itself behind these flaps, which, 
when the ventricle is passive, hang loosely in its cavity, and 
forces them before it until they come together, their apices 
meeting in the centre of the opening. The segments, which 
are quite flexible, are kept from being forced into the auricle 
by the attachment of a number of muscular and tendinous 
cords which hold them in the ventricle. The muscular columns 
are called columnae carneae, and are divided into three sets, 
arranged as follows: Some form mere ridges, being attached 
to the wall of the ventricle throughout their length; the second 
set are attached to the wall of the ventricle by each end and 
are free in the middle; while the third are attached by one end 
only to the ventricular wall, terminating at the other in ten- 
dinous cords, which are themselves attached to the ventricular 
aspect of the segments of the valve, and are only long enough THE VISCERA. 
231 
to allow these to close without floating into the auricle. The 
valve thus formed is known as the tricuspid, and the tendinous 
cords as chordae tendineae. 
The blood, driven by the contraction of the venous ventricle, 
is forced into the pulmonary artery, and, when the ventricle 
ceases to contract, would again return to it were it not for a 
valvular arrangement here, called the pulmonary semi-lunar 
valve, which guards the orifice of the pulmonary artery. The 
semi-lunar valve is three segments arranged around the in- 
terior of the pulmonary artery, just at its commencement. 
Each segment is semi-lunar in shape, its convex border being 
attached, while the superior border is free and straight. They 
consist of folds of lining membrane, strengthened by fibrous 
tissue, which, just at the centre of the free edge, is aggregated 
into a projection called corpus Arantii. In the centre the valve 
lacks fibrous tissue and presents a lunated space. Behind each 
segment there is a depression caused by a dilatation of the 
artery, called sinus of Valsalva. When the ventricle ceases to 
contract the blood, seeking to re-enter the cavity, enters the 
sinuses of Valsalva and forces the segments together until they 
meet along their free edges and close the orifice. The corpora 
Arantii have small effect in closing this orifice. 
The objects seen in the right ventricle, then, are: 1, columnae 
carneae; 2, chordae tendineae; 3, venous auriculo-ventricular 
opening; 4, opening into pulmonary artery; 5, tricuspid valve; 
6, semi-lunar valve; 7, foramina Thebesii. 
The arterial auricle (atrium sinistrum) has thicker walls 
than the venous, being about one-eighth inch thick, while the 
right is only one-twelfth inch. It presents musculi pectinati, 
which are fewer in number than in the right auricle, being 
almost confined to the appendix auriculae; the arterial auriculo- 
ventricular opening; the openings for the four pulmonary 
veins, which return the blood from the lungs. Two of these 
veins come from each lung, the two from the left sometimes 
uniting before entering the auricle. 
To sum up, we have: 1, openings for four pulmonary veins; 
2, arterial auriculo-ventricular opening; 3, musculi pectinati. 232 
DESCRIPTIVE ANATOMY. 
The arterial ventricle (ventriculum sinister) has walls three 
times as thick as those of the venous, being seven lines thick, 
while the venous is only about two and a half lines. The left 
side of the heart, therefore, is much more powerful than the 
right, this being due to the fact that while the venous ventricle 
has only to drive the blood into the lungs, the arterial has to 
send it throughout the entire system. On the walls of the 
arterial ventricle are seen columnae carneae much more promi- 
nent and more intimately intersecting than in the venous ven- 
tricle, but similar to them in arrangement, viz.: Some at- 
tached throughout their length, some attached at each end and 
free in the middle, some attached at one end to the wall of 
the ventricle, while the other end terminates in tendinous cords 
attached to the ventricular aspect of the bicuspid valve. The 
blood is forced from the arterial auricle into the arterial ventri- 
cle, and when this contracts it is forced into the aorta. Both 
these openings are guarded by valves. The valve guarding 
the arterial auriculo-ventricular opening is known as the bi- 
cuspid, or mitral, and is arranged upon the same principle as 
the tricuspid, being made up of two segments attached by their 
bases to the fibrous ring around the opening, while their apices 
are free in the cavity of the ventricle. It consists of folds of 
endocardium strengthened by fibrous and muscular tissue and 
receives the attachment of the chordae tendineae. It differs from 
the tricuspid valve in being stronger and in having only two 
segments. The opening into the aorta is guarded by the aortic 
semi-lunar valve, which is in every way the counterpart of the 
pulmonary semi-lunar, except in being larger and stronger, 
consists of three segments of lining membrane and fibrous 
tissue, with corpora Arantii, lunated spaces and sinuses of 
Valsalva. The mechanism of their action is also the same as 
in the pulmonary semi-lunar. 
To sum up, there are in the arterial ventricle: 1, columnae 
carneae; 2, chordae tendineae; 3, arterial auriculo-ventricular 
opening; 4, aortic opening; 5, bicuspid valve; 6, aortic semi- 
lunar valve. THE MUSCULAR SYSTEM. 
233 
THE MUSCULAR SYSTEM. 
When an incision is made in any part of the body, the follow- 
ing structures, from without inward, are met with: 1, skin; 
2, superficial areolar fascia whose existence allows the free 
movement observed in almost every part of the integument. 
It consists of two layers, between which is generally found 
fatty tissue, varying in quantity in different parts of the body; 
3, beneath the superficial fascia, in some parts of the body, 
are found the muscles with their proper investing fascia; while 
in others there is interposed between them and the superficial 
fascia a strong, and more or less thick membrane, called 
the investing fascia, or deep fascia which frequently gives off 
from its deep face partitions, which separate different groups 
of muscles. 
The function of muscles is to produce movement, most of 
them being attached at both extremities to bone, some having 
no bony attachment, while others are attached to bone by one 
extremity the other terminating in some soft tissue. When a 
muscle is attached to bone by both extremities a movable joint 
is invariably found between the two extremities, otherwise no 
movement would occur when the muscle attempted to contract, 
so that those muscles, which lay hold of bone at both extremities, 
are attached to different bones at either end. The two attach- 
ments of a muscle are spoken of, one as the origin, the other 
as the insertion, the origin being usually that attachment suscep- 
tible of the least motion, and as a rule, especially true of the 
limbs, the origin is the point nearest the body, or the mid-line 
of the body. The action of a muscle consists in the shortening 
of its length, thus drawing the parts to which it is attached 
nearer to the origin by movement of the part into which it is 
inserted. Some movements are too complex to be brought about 
by one muscle and result from the co-ordinated action of several. 
The striated muscles are the red, fleshy portion of the body, 
though generally a muscle consists of two parts: the red fibres, 
gathered into bundles, fasciculi, forming a coarse, or a fine 
muscle, and a white, tougher, stronger portion called its tendon. 
With a few exceptions the tendon is found at the extremities 234 
DESCRIPTIVE ANATOMY. 
of the muscle, and, as it is so much stronger, bulk for bulk, 
the tendon is much the smaller part of the muscle, thus econom- 
izing space at the. attachments. The portion of muscle between 
its tendons of origin and insertion is called the belly of the 
muscle. In a few instances a muscle has two bellies, since it 
may have a central tendon. 
The names of most muscles are derived from one of the fol- 
lowing facts: 1, the position which it occupies; 2, its shape; 
3, the direction of its fibres; 4, its attachments; 5, its action; 
6, the number of its points of origin; 7, the arrangement of its 
tendon. 
The Abdominal Muscles. 
The anterior abdominal wall is formed chiefly by six flat, 
thin muscles, three on each side of the middle line, called the 
broad muscles of the abdomen. Besides these there are two 
other pairs, the pyramidales, small and insignificant, and the 
recti which are long and narrow. The abdominal wall con- 
sists of the following structures from without inward, viz.: 1, 
integument; 2, two layers of superficial fascia with fatty tissue 
interposed; 3, the external oblique muscle; 4, the internal ob- 
lique muscle; 5, the transversalis muscle; 6, the transversalis 
fascia; 7, the parietal layer of peritoneum. These muscles all 
terminate in tendinous fibres as they approach the median line; 
and, since there is no bone for them to seize, their fibres inter- 
lock, forming a white line extending from the ensiform cartilage 
to the symphysis pubis called the linea alba. The whole line 
is sunken below the surrounding surface and presents about its 
centre the umbilicus or navel. The sunken appearance is caused 
by the bulging of the recti, which lie on either side of it, the 
width of the linea alba corresponding to the interval between 
the recti. 
External Oblique. 
The external oblique muscle of the abdomen derives its 
name from the downward and inward direction of its fibres 
and from its position, being external to another oblique muscle. 
It arises by eight fleshy tooth-like processes or digitations from THE MUSCULAR SYSTEM. 
235 
the anterior surfaces of the eight lower ribs. The upper five 
digitations interlock with similar processes of the serratus mag- 
nus, the lower three with the latissimus dorsi. From their 
origin the fibres pass downward and inward, the digitations 
gradually blending to form the belly of the muscle which, toward 
the front of the abdomen terminates in a thin, flat tendon, 
called an aponeurosis, which is inserted into the linea alba from 
the sternum to the symphysis pubis. The posterior fibres pass 
almost vertically downward and are inserted into about the 
anterior one-half or two-thirds of the outer lip of the crest of 
the ilium; while the intermediate fibres are inserted into the 
anterior superior spinous process of the ilium and into the spine 
and pectineal line of the pubis. That portion of the aponeurosis 
which extends from the anterior superior spinous process of the 
ilium to the spine of the pubis is called Poupart's ligament. It is 
the lower border of the aponeurosis, is free between its points 
of attachment and folded slightly inward on itself. About an 
inch from the spine of the pubis Poupart's ligament sends down- 
ward some fibres which are inserted into the pectineal line of 
the pubis, forming Gimbernat's ligament, which is triangular 
in shape with its apex within and its base extending for about 
an inch outward. 
At the lower, inner part of the aponeurosis is seen an open- 
ing, near the symphysis pubis, called the external abdominal 
ring. It is formed by a separation of the fibres of the aponeu- 
rosis, is triangular in shape and oblique in direction, its apex 
being upward and outward and its base downward and in- 
ward at the crest of the pubis. The edges of the aponeurosis 
which forjn the sides of the ring are called its pillars, internal 
and external, the external being inserted into the spine of the 
pubis and the internal interlocking with the internal pillar of 
the opposite side over the front of the pubis. For a short dis- 
tance the apex of the ring is obscured by some curved fibres 
called inter-columnar fibres. The external abdominal ring 
transmits in the male the spermatic cord and in the female 
the round ligament. 236 
DESCRIPTIVE ANATOMY. 
Internal Oblique. 
The internal oblique muscle of the abdomen derives its 
name from the upward and inward obliquity of its fibres and 
from the position it occupies just beneath the external oblique. 
It arises by means of a thin tendinous membrane, called the 
fascia lumborum, from the spinous processes of the lumbar 
vertebrae, from the anterior two-thirds of the middle lip of the 
crest of the ilium, and from the outer half of Poupart's liga- 
ment. 
The fascia lumborum terminates in fleshy fibres on the side 
of the abdomen, and those fibres springing from the crest of the 
ilium are also fleshy: these radiate somewhat, the general direc- 
tion, however, being upward and inward, and are inserted, pos- 
teriorly, into the cartilages of the four lower ribs; while on 
the front of the abdomen the fibres become aponeurotic and 
are inserted into the whole length of the linea alba. The fleshy 
fibres which rise from the outer half of Poupart's ligament 
are blended with fibres of the transversalis which arise from 
the same part of the ligament. These blended fibres arch down- 
ward and inward and form, so long as they remain fleshy, the 
conjoined arch, but as they descend they become tendinous, 
forming the conjoined tendon which is inserted into the crest 
and pectineal line of the pubis. By reason of the arched direc- 
tion of these fibres there is a short space called the internal 
abdominal ring, between them above and Poupart's ligament 
below, their conjoined arch without and conjoined tendon within, 
where the wall of the abdomen has but one muscular element, 
viz.: the aponeurosis of the external oblique. If an incision were 
made at this point we would pass through: 1, the integument; 
2, two layers superficial fascia; 3, the aponeurosis of the external 
oblique; 4, transversalis fascia and the parietal layer of the 
peritoneum. The conjoined tendon descends just behind the 
external abdominal ring, so that at this point the wall is want- 
ing in only one muscular element-the aponeurosis of the ex- 
ternal oblique. THE MUSCULAR SYSTEM. 
237 
Transversalis. 
The transversalis derives its name from the horizontal di- 
rection of its fibres. It lies just beneath the internal oblique 
and is the deepest of the three broad muscles of the abdomen. 
It arises by means of an aponeurosis, the fascia lumborum, 
from the transverse and spinous processes of the lumbar ver- 
tebrae, fleshy from the inner aspect of the cartilages of the 
six inferior ribs, interlocking with the diaphragm, fleshy from 
the anterior two-thirds of the inner lip of the crest of the ilium 
and fleshy from somewhat less than the outer half of Poupart's 
ligament. The posterior aponeurosis becomes fleshy on the side 
of the abdomen and these fibres, being reinforced by those which 
arise from the costal cartilages and crest of the ilium, pass 
forward, become aponeurotic and are inserted into the whole 
length of the linea alba. The fibres which rise from Poupart's 
ligament blend with those of the internal oblique to form the 
conjoined arch and conjoined tendon which is inserted into the 
crest and pectineal line of the pubis. 
Rectus. 
The rectus abdominis derives its name from the straight 
course of its fibres. It lies on the front of the abdomen, beside 
the linea alba, surrounded by the aponeuroses of the three broad 
muscles of the abdomen. It is flat and ribbon-like in shape. 
It arises by a flat tendon from the front of the symphysis pubis 
and crest of the pubis; as it ascends it becomes fleshy and broader 
and terminates by three digitations which are inserted into the 
fifth, sixth and seventh cartilages just beside the sternum. In 
the upper half of its course the rectus presents three or four 
tendinous intersections which are called lineae transversal. Be- 
fore the aponeurosis of the external oblique has been removed, 
the outer edge of the rectus presents a curved ridge called 
linea semi-lunaris. 
The rectus as it ascends is enclosed between the aponeuroses 
of the three broad muscles, and these form what is called its 
sheath. This sheath is complete in front for the whole length 238 
DESCRIPTIVE ANATOMY. 
of the muscle, but behind is wanting for its lower fourth. It 
is thus formed: for the upper three-fourths of the rectus, or 
from a point half way between the umbilicus and the symphysis 
pubis upward to its insertion, the rectus has in front the aponeu- 
rosis of the external oblique and half the aponeurosis of the 
internal oblique; while for the same distance behind it has 
the aponeurosis of the transversalis and half of the aponeurosis 
of the internal oblique, the latter aponeurosis splitting, when 
it reaches the outer edge of the rectus, sending one layer in 
front and the other behind that muscle. Of course it also has 
behind it the transversalis fascia and the parietal layer of peri- 
toneum separating it from the abdominal cavity. For its lower 
fourth, that is, downward from the point midway between the 
umbilicus and symphysis pubis, all three aponeuroses pass in 
front of it; and behind it is separated from the abdominal 
cavity only by the parietal layer of the peritoneum and the 
transversalis fascia. Where the sheath ends behind it is curved 
and is called the fold of Douglas. 
Pyramidalis. 
The pyramidalis abdominis is small and derives its name 
from its pyramidal shape. It is found in the sheath of the 
rectus, in front of its lower portion, and is frequently absent 
on one or both sides. It arises from the front of the crest of 
the pubis and passes upward, tapering as it ascends to be in- 
serted into the linea alba half way to the umbilicus. 
Action-The abdominal muscles are agents of expulsion as in 
voiding the urine and faeces and in terminating labor. They 
are also agents of forced expiration, for when they contract 
they diminish the size of the abdominal cavity, forcing the 
abdominal viscera against the walls of that cavity and thus 
driving the diaphragm upward, while at the same time, by 
drawing down the ribs, they in a measure diminish the size 
of the thorax. 
They can also, acting from below, flex the body on the pelvis; 
or, acting from above, draw the pelvis and lower extremities 
upward on the body. One external oblique, acting alone, would THE MUSCULAR SYSTEM. 
239 
draw the body downward and to the side opposite the muscle 
acting. Of course, if the fixed point be above, it would draw 
the pelvis upward and towards the muscle which is acting. The 
internal oblique of one side may act in concert with the external 
oblique of the opposite side. The transver sales, acting together, 
compress the abdominal contents backward. The recti, when 
the lower attachment is fixed, draw the body downward; or, 
when acting from above, will draw the pelvis upward. The 
pyramidales are tensors of the linea alba. 
These muscles are supplied by the lower intercostal nerves 
and the ilio-hypogastric. Blood is received from the lumbar, 
lower intercostal, deep epigastric and internal mammary. 
Diaphragm. 
1. Definition and position-The diaphragm is the arched mus- 
cular septum between the two cavities of the trunk, presenting 
its upper convex surface as the floor of the thorax and its 
equally concave under surface as the roof of the abdomen. 
2. Relations-By its upper surface it supports the pleura on 
either side, containing the lungs, and the pericardium in the 
centre, containing the heart. Below it is covered by peritoneum 
and is in relation with the liver, spleen, stomach, pancreas and 
kidneys. 
3. Origin-In front it arises from the posterior surface of 
the sternum, on each side from the inner surface of the six 
lower ribs and from a ligamentum arcuatum externum and in- 
ternum, behind from the front of the vertebral column by two 
crura. 
4. Its points of origin studied individually. 
(a) Between that part which arises from the posterior sur- 
face of the sternum and that part on each side which arises 
from the adjacent ribs there usually exists a fissure for a short 
distance, the muscular structure here being wanting, the aper- 
ture which would otherwise exist, between the thoracic and ab- 
dominal cavities being closed by other structures. 240 
DESCRIPTIVE ANATOMY. 
(b) The origin from the inner surface of the ribs is by 
digitations which interlock with similar digitations of the trans- 
versalis abdominis. 
(c) The lig amentum arcuatum externum arches across the 
quadratus lumbordum muscle from the apex of the twelfth 
rib to the apex of the transverse process of the first or second 
lumbar vertebra, usually the second. 
(d) The ligamentrim arcuatum internum arches over the 
psoas magnus muscle from the apex of the transverse process 
of the first or second lumbar vertebra to be lost in the crus of 
the same side. 
(e) The right crus arises tendinous from the front of the 
bodies of the second, third and fourth lumbar vertebrae. 
(/) The left crus arises tendinous from the front of the 
bodies of the second and third lumbar vertebrae. It is smaller 
as well as shorter than the right. 
5. The appearances which it presents. 
The muscular fibres of the diaphragm, as they are making 
for the centre, become tendinous. The central portion, there- 
fore, is called the tendinous portion and is arranged like a clover 
leaf, presenting a central, a right and a left leaflet; the tendon 
is therefore called trefoil. 
The diaphragm is pierced by three large apertures which 
are for the transmission of the following structures, viz.: 1, 
descending aorta vena azygos major, thoracic duct and some- 
times the sympathetic nerve; 2, the ascending vena cava; 3, 
oesophagus and pneumogastric nerves. 
The crura, as stated, arise tendinous from the front of the 
vertebral column, but as they ascend they become fleshy and 
leave a slight interval between them. Over the front of the 
twelfth dorsal vertebra each crus gives off from its inner side 
a bundle of fibres which crosses obliquely to join the opposite 
crus, the one from the right crus being usually in front. This 
interchange of fibres is known as the decussation of the crura 
and it leaves between its commencement and the vertebral 
column an opening which is known as the aortic. This opening 
is over the front of the body of the twelfth dorsal vertebra, THE MUSCULAR SYSTEM. 
241 
generally slightly to the left of the middle line, but sometimes 
on it. The opening is behind the diaphragm and not through it. 
The decussating fibres, after passing into the opposite crus, 
again separate from each other leaving an opening around 
which they again unite. This is the oesophageal opening and 
is situated above and to the left of the aortic opening, between 
it and the middle leafllet, and about opposite the tenth dorsal 
vertebra. 
The opening for the inferior vena cava is to the right of the 
middle line, between the right and middle leaflet of the tendinous 
centre and about opposite the ninth dorsal vertebra. 
6. Action-The diaphragm is a respiratory muscle and an 
agent of expulsion. When it contracts, as it does eighteen to 
twenty times a minute, it descends, becoming less arched arid 
thus increasing the size of the thorax while it decreases the 
size of the abdomen, though the latter is compensated by the 
bulging of the anterior abdominal walls; but should it be neces- 
sary to exert a straining effort, as in voiding the urine or faeces 
or in parturition, the muscles of the abdominal wall contract 
at the same time that the diaphragm does, so that the abdominal 
cavity is diminished in size from above downward as well as 
from before backward, and its viscera subjected to compres- 
sion. When the diaphragm relaxes it again ascends, thus les- 
sening the size of the thoracic cavity. 
The diaphragm is supplied by the phrenic nerves. Blood ves- 
sels come from the internal mammary and from the phrenic 
branches of the abdominal aorta. 
Quadratus Lumborum. 
The quadratus lumborum is a quadrilateral muscle found in 
the posterior abdominal wall, in the lumbar region lying beside 
the vertebral column. It is enclosed between the middle and 
anterior lamella of the posterior aponeurosis of the transversalis; 
It arises from the last rib and descends, being attached by 
its inner edge to the transverse processes of the lumbar ver- 
tebrae, to be inserted into the posterior one-fifth of the crest 
ilium and the ilio-lumbar ligament. 242 
DESCRIPTIVE ANATOMY. 
Action-It draws the vertebral column to one side, and acts 
as an inspiratory agent by fixing the last rib and preventing the 
diaphragm from drawing it inward. The two muscles, acting 
together, assist in flexing the body; while either may bend the 
trunk to its own side. 
The nerves and arteries are from the anterior branches of 
the lumbar nerves and arteries. 
Muscles of the Neck. 
When the skin has been removed from the neck, it reveals a 
superficial fascia, thin and delicate, continuous below with that 
which covers the thorax and above with that on the face. Be- 
neath this is the platysma myoides muscle, and, on removing 
this, we encounter the deep or investing cervical fascia. 
This fascia is a dense membrane firmly attached behind to 
the spinous processes of the cervical vertebrae, where it blends 
with the origin of the muscles in that region, and completely 
encircles the neck. Below it is in part attached to the clavicle 
and sternum, in part it blends with the deep fascia covering 
the thoracic muscles while another portion passes into the tho- 
racic cavity, where it blends with the pericardium and the 
fascia supporting the great vessels. Above it is attached to 
the lower jaw, covers in the parotid gland and gives off some 
bands considered as ligaments. Like all investing, or envelop- 
ing, fascias, it divides into layers, or septa, which form sheaths 
for neighboring muscles, vessels, nerves and other structures. 
Leaving the cervical spines in a single layer, it splits to en- 
close the trapezius; uniting, at the anterior border of that muscle 
to cover in the triangular interval between it and the sterno- 
mastoid, the two layers again divide and form a sheath for the 
latter muscle, and, again uniting, they pass forward as a single 
layer to the mid-line of the body in front, where the fascia of 
the opposite side of the neck blends with the one described. 
Of the numerous septa given off from the deep surface of this 
fascia are: one which forms a delicate sheath for the infra- 
hyoid group of muscles; one which envelops the trachea, called 
pre-tracheal fascia, and one which passes in front of the pre- THE MUSCULAR SYSTEM. 
243 
vertebral muscles and is called the pre-vertebral fascia. From 
the pre-tracheal and pre-vertebral fascias is derived an import- 
ant layer which forms the sheath of the carotid vessels. 
The muscles of the neck are divided into a superficial and 
a deep group; the former containing two muscles and the latter 
nine subdivided into supra- and infra-hyoid groups, or elevators 
and depressors of the hyoid bone. 
Superficial Group. 
Platysma Myoides. 
Sterno-Cleido-Mastoid. 
Platysma Myoides. 
When the integument and superficial fascia have been re- 
moved from the front and side of the neck there is seen a thin 
pale broad muscle called the platysma myoides. It arises from 
the fascia covering the pectoralis major and deltoid muscles, 
and passes upward and inward over the clavicle to cover the 
side and front of the neck. Its innermost fibres are interlocked 
with the fibres of the opposite muscle along the upper part of 
the middle line of the neck; the others are inserted into the 
inferior maxilla, some passing over it to be lost in the side of 
the face and some continuing to the angle of the mouth; these 
last are joined by some accessory fibres which take their origin 
on the side of the face from the fascia covering the masseter 
muscle. These fibres have been considered as a separate muscle 
called risorious Santorini or laughing muscle. 
Action-It is a depressor of the lower jaw. It can draw the 
angle of the mouth downward so as to produce a melancholy 
expression or carry it backward as in laughing. 
Sterno-Cleido-Mastoid. 
The sterno-cleido-mastoid is the second muscle in the super- 
ficial group and lies beneath the platysma between two layers 
of the deep cervical fascia. It is one of the most important 244 
DESCRIPTIVE ANATOMY. 
muscles in the body and derives its name from its origin and 
part of its insertion. 
It arises by a forked origin. One fork, a more or less rounded 
tendon, springs from the upper front part of the manubrium; 
the other, musculo-tendinous, arises from about the inner one- 
third or one-half of the clavicle. This origin is very variable. 
An interval, filled by fibrous tissue usually exists between the 
two heads. The muscle passes obliquely upward, backward and 
a little outward on the side of the neck and is inserted into the 
mastoid portion and process of the temporal bone and into the 
adjacent part of the superior curved line of the occipital. Be- 
tween its two origins there is a fissure which extends upward 
for some distance. 
Action-When both muscles act they bow the head forward; 
when one acts it draws the head to that side, turning the face 
somewhat to the opposite side. 
Arteries and Nerves-The arteries are the sterno-mastoid 
branches of the external carotid and occipital. The nerves are 
the spinal accessory and a branch from the cervical plexus. 
Depressors of the Hyoid Bone. 
Sterno-Hyoid. 
Sterno-Thyroid. 
Thyro-Hyoid. 
Omo-Hyoid. 
These muscles are arranged in two layers, the two sterno- 
hyoids and omo-hyoids forming the one in front and the sterno- 
thyroids and the thyro-hyoids forming the one behind. By 
their inner edges the sterno-hyoids and thyro-hyoids are in 
contact, save for a small triangular space just above the ster- 
num. The anterior belly of the omo-hyoid is also, through the 
greater part of its course, in contact with the outer edge of 
the sterno-hyoid. After the deep fascia has been removed these 
muscles are widely separated and show between them much 
larger triangular spaces than really exist. THE MUSCULAR SYSTEM. 
245 
Sterno-Hyoid. 
The sterno-hyoid derives its name from its attachments. 
It is ribbon-like in shape and vertical in direction. It arises 
from the posterior aspect of the manubrium stemi and from 
the inner extremity of the clavicle or sterno-clavicular liga- 
ment, and ascends the neck beside the middle line to be inserted 
into the hyoid bone. 
Sterno-Thyroid. 
Lying behind the sterno-hyoid and slightly broader than it, 
is another ribbon-like muscle called, from its attachments, 
sterno-thyroid. It arises from the posterior surface of the 
manubrium and from the cartilage of the first rib, and, ascend- 
ing beside the middle line, is inserted into the oblique ridge 
on the ala of the thyroid cartilage. Below it is often trans- 
versed by a tendinous intersection as is the sterno-hyoid. 
Thyr o-Hyoid. 
The thyro-hyoid is a short ribbon-like muscle which con- 
tinues the course of the sterno-thyroid to the hyoid bone, and 
derives its name from its attachments. It arises from the 
oblique ridge on the ala of the thyroid cartilage and is inserted 
into the hyoid bone. Frequently some of the fibres of the sterno- 
thyroid are continued directly into this muscle. 
Omo-Hyoid. 
The omo-hyoid derives its name from its attachments. It 
is a double-bellied muscle passing with a curve across the side 
of the neck. 
It arises from the upper border of the scapula, near the supra- 
scapular notch, and from the ligament stretched across the 
notch, and passes forward, inward and slightly upward until, 
beneath the stemo-cleido-mastoid, it becomes tendinous, its pos- 
terior belly ceasing. It then again becomes fleshy, forming the 246 
DESCRIPTIVE ANATOMY. 
anterior belly, and passes nearly upward but with a slight in- 
clination inward, to its insertion in the hyoid bone at the junc- 
tion of its body and greater cornu. The central tendon is held 
down, so as to give the muscle its curve, by a loop of fascia which 
is said to pass to the cartilage of the first rib. 
Action-The depressors of the hyoid bone, as the name in- 
dicates, draw the hyoid bone down. The sterno-thyroid draws 
down the larynx and the two omo-hyoids, acting together, draw 
the hyoid bone downward and backward. The omo-hyoid of 
either side, acting alone, might draw the hyoid bone downward, 
backward and toward that side. The thyro-hyoids have the 
important action of drawing the thyroid cartilage, and of course 
the larynx, upward under the hyoid bone, protecting the larynx 
in swallowing. 
Arteries and Nerves. Nerve supply from descendens noni, 
except the thyro-hyoid which is supplied by the hypogastric. 
Arteries superior and inferior thyroid. 
Elevators of the Hyoid Bone. 
Digastric. 
Mylo-Hyoid. 
Stylo-Hyoid. 
Genio-Hyoid. 
Genio-Hyoid-Glossus. 
Digastric. 
The digastric, as its name indicates, is a double-bellied 
muscle. It is round in shape, curved in direction and found at 
the upper part of the side of the neck. It arises fleshy from the 
digastric fossa of the temporal bone and passing forward and 
downward, becomes tendinous; the portion between its origin 
and central tendon being called the posterior belly. It then 
again becomes fleshy, forming the anterior belly, and passing 
forward is inserted into the digastric fossa of the inferior 
maxilla. The central tendon pierces obliquely the belly of a 
small muscle which lies beside it called the stylo-hyoid, and, THE MUSCULAR SYSTEM. 
247 
after emerging from it, plays through a loop of fascia which 
binds it down to the hyoid bone. 
Stylo-Hyoid. 
The stylo-hyoid is a small muscle found lying beside the pos- 
terior belly of the digastric and deriving its name from its 
attachments. It arises from the outer side of the styloid pro- 
cess of the temporal bone, and passing forward and downward 
is inserted into the hyoid bone. Just before its insertion it is 
pierced by the central tendon of the digastric. 
Mylo-Hyoid. 
The mylo-hyoid is a broad, thin, triangular muscle which 
forms the floor of the mouth. It arises from the whole length 
of the mylo-hyoid ridge, and, passing nearly inward, with a 
slight inclination downward, and backward, the greater portion 
of the muscle meets its fellow of the opposite side on the middle 
line, forming a raphe, while some of its posterior fibres are in- 
serted into the body of the hyoid bone. 
Genio-Hyoid. 
The genio-hyoid is a small muscle which slightly increases 
in size as it descends. It lies above the mylo-hyoid just beside 
the middle line. It arises from the inferior spina mentalis and 
passes backward and slightly downward to be inserted into the 
hyoid bone, near the middle of its body. 
Genio-Hyo-Glossus. 
The GENIO-HYO-GLOSSUS is a thin, radiating fan-shaped muscle. 
It arises by a narrow tendinous origin from the superior spina 
mentalis and immediately radiates, fleshy, to be inserted into the 
under surface of the tongue from its base to near its apex, 
some of its lower fibres being inserted into the hyoid bone. This 
muscle lies close to the middle line beside its fellow. 248 
DESCRIPTIVE ANATOMY. 
Action-The general function is that of elevation of the hyoid 
bone or depression of the lower jaw. The posterior bellies of 
the digastric can carry the hyoid backward and upward, while 
the anterior bellies carry it forward and upward. The stylo- 
hyoid acts in concert with the posterior belly of the digastric. 
The posterior belly of one digastric, and the stylo-hyoid draw 
the hyoid backward and upward and to the side of the muscle 
acting. The mylo-hyoid acts like a swing, which, by shorten- 
ing its fibres, can elevate the floor of the mouth. The posterior 
fibres can draw forward and upward the hyoid bone. The genio- 
hyoid pulls the hyoid bone, and with it the tongue, upward and 
forward. The genio-hyo-glossus may pull the hyoid upward, 
slightly, but its main function is in moving the tongue, which 
it draws forward and upward. 
Nerves. Stylo-hyoid and posterior belly digastric by the 
facial,-genio-hyoid and genio-hyo-glossus by the hypoglossal; 
mylo-hyoid and anterior belly of digastric by inferior dental. 
Surgical Triangles of the Neck. 
The side of the neck presents a quadrilateral surface which 
is bounded below by the clavicle, above by the body of the in- 
ferior maxilla and an imaginary horizontal line passing from 
its angle to the mastoid process of the temporal bone, in front 
by the middle line and behind by the anterior edge of the 
trapezius. 
This space is subdivided by the sterno-mastoid into a great 
anterior and a great posterior triangle. The anterior triangle 
is bounded as follows: in front by the middle line, behind by 
the sterno-cleido-mastoid, above by the body of the lower jaw 
and the imaginary line. The base is above, the apex below. 
The posterior triangle has its base below, formed by the clavicle. 
It is bounded in front by the sterno-cleido-mastoid and behind 
by the anterior edge of the trapezius. 
Each of these triangles is again subdivided into smaller ones. 
The anterior is divided into three: 
1. The inferior carotid triangle, or triangle of necessity, is 
bounded in front, by the median line; behind, by the anterior THE MUSCULAR SYSTEM. 
249 
margin of the sterno-mastoid; above, by the anterior belly of 
the omo-hyoid. Its base is internal. 
2. The superior carotid triangle, or triangle of election, is 
bounded behind by the sterno-mastoid; below, by the anterior 
belly of the omo-hyoid; above, by the posterior belly of the 
digastric. Its base is external. 
3. The digastric or submaxillary triangle has its base formed 
by the lower jaw and the imaginary line; and its sides formed, 
posteriorly, by the posterior belly of the digastric and stylo- 
hyoid; anteriorly, by the anterior belly of the digastric. 
The great posterior triangle is subdivided into two: 
1. The suboccipital triangle has its base below. It is bounded 
in front by the sterno-mastoid; behind, by the anterior edge of 
the trapezius; below, by the posterior belly of the omo-hyoid. 
2. The subclavian triangle has its base below. It is bounded 
above by the posterior belly of the omo-hyoid; in front, by the 
sterno-mastoid; below, by the clavicle. It contains the sub- 
clavian artery and vein and the brachial plexus of nerves. In 
the posterior triangle the subdivisions are made by the posterior 
belly of the omo-hyoid; in the great anterior triangle by the 
anterior belly of the omo-hyoid, and the two bellies of the 
digastric. 
The Scaleni Muscles. 
The two scaleni form part of a group called praevertebral. 
The two scaleni muscles are distinguished as scalenus anticus 
and posticus. A small portion of the scalenus posticus is some- 
times individualized as the scalenus medius. These muscles 
are of great importance owing to the fact that they occupy a 
position in the lower part of the side of the neck, and come 
into important relation with the subclavian artery and brachial 
plexus of nerves. 
Scalenus Anticus. 
The scalenus anticus, triangular in shape, arises from the 
anterior tubercles of the transverse processes of the third, 
fourth, fifth and sixth cervicle vertebrae by tendinous slips, 250 
DESCRIPTIVE ANATOMY. 
which, uniting as they descend, form the muscle. It is inserted 
by a narrow tendon into the upper surface of the first rib. 
Scalenus Medius. 
The SCALENUS medius arises from the posterior tubercles 
of the transverse process of all the cervical vertebrae except the 
first. It descends and divides into two portions, one of which 
is inserted into the first rib in front of the tubercle. 
Scalenus Posticus. 
The scalenus posticus arises from the posterior tubercles 
of the transverse processes of the two or three lower cervical 
vertebrae and is inserted into the outer surface of the second rib. 
The scaleni, acting from above, draw up the first and second 
ribs, being muscles of inspiration. Acting from below they 
can draw the neck downward and to the side of the muscles 
acting; or, the muscles of both sides acting, can flex the spinal 
column. 
The nerve supply is from the lower three cervical nerves. 
Pre vertebral Group. 
Rectus Capitis Anticus Major. 
Rectus Capitis Anticus Minor. 
Longus Colli. 
Rectus Capitis Lateralis. 
Rectus Capitis Anticus Major. 
This muscle, the longus capitis, arises from the anterior 
tubercles of the transverse processes of the third, fourth, fifth 
and sixth cervical vertebrae by small tendinous fasciuli which 
terminate in a flattened muscle. The muscular fibres terminate 
in a flat aponeurosis which is inserted into the basilar process 
of the occipital, in front of the foramen magnum. THE MUSCULAR SYSTEM. 
251 
Rectus Capitis Anticus Minor. 
This is a small muscle, the rectus capitis anterior, lying be- 
neath the preceding and further from the mid-line. It arises 
from the transverse process of the atlas and is inserted into 
the basilar process of the occipital, slightly external to the pre- 
ceding. 
Rectus Capitis Lateralis. 
This muscle belongs properly to the lateral vertebral region 
and is an inter-transverse muscle. It arises from the trans- 
verse process of the atlas and is inserted into the jugular pro- 
cess of the occipital. 
Longus Colli. 
This muscle might be appropriately described as three. One 
arises from the transverse process of the third, fourth and 
fifth cervical vertebrae and is inserted into the transverse pro- 
cess of the atlas. The second arises from the bodies of the 
upper three dorsal vertebrae and is inserted into the transverse 
processes of the third and fourth cervical. The third division 
arises from the three upper dorsal and four lower cervical, and 
is inserted into the second and third cervical. 
The muscles act so as to flex and rotate the head and cervical 
vertebrae. 
Anterior branches from the cervical nerves supply these 
muscles. 
The Muscles of the Back. 
These muscles are arranged in several superimposed layers 
and are covered by a superficial fascia which varies in thick- 
ness in different regions. In some situations, as in the lum- 
bar region, it usually contains a large amount of fat; in other 
portions it is a thick, loosely-woven connective tissue, not easily 
divisible into layers, but everywhere allows free movement of 
the skin. Many of the muscles arise from, or are covered by, 
a dense connective tissue forming the vertebral aponeurosis. 
This fascia is attached to the spines and transverse processes 252 
descriptive anatomy. 
of the vertebrae from which points it sends out septa which 
not only give origin to muscular fibres, but serve as sheaths for 
some of the muscles. 
First Layer. 
Trapezius 
Latissimus Dorsi 
Trapezius. 
The trapezius arises from the superior curved line of the 
occipital bone, from the posterior occipital protuberance and 
from the spinous processes of all the dorsal and cervical verte- 
brae. The fibres converge outward, some ascending obliquely, 
some descending obliquely and some running horizontally, to 
reach the insertion into the outer third of the clavicle, the 
acromion process and whole length of the spine of the scapula. 
Its insertion is stated in the same terms as the origin of the 
deltoid. 
Extending from the posterior occipital protuberance to the 
seventh cervical vertebra, and attached to the intervening 
spinous processes, is a fibrous cord called ligamentum nuchae; 
and it is in reality from this cord that the trapezius arises. 
Nearly the whole of the origin of this muscle is tendinous. The 
central portion of the tendon is broad and thin and forms a 
diamond-shaped space between the two muscles. 
Action-According to the direction of the fibres which act it 
can draw the scapula directly backward, downward and back- 
ward or upward and backward. 
Latissimus Dorsi. 
The latissimus DORSI arises from the spinous processes of 
the lower four or six dorsal vertebrae, all the lumbar vertebra 
and the spinous tubercles of the sacrum, from the posterior third 
of the crest of the ilium and by fleshy slips from the three or 
four lower ribs. The muscle is tendinous at its origin except 
that part arising from the ribs. As it passes upward and out- 
ward the fibres converge, become thicker and fleshy, and, pass- 
ing over the lower angle of the scapula, wind around the teres THE MUSCULAR SYSTEM. 
253 
major to be inserted along with it into the posterior bicipital 
ridge of the humerus. The tendon of the teres major is wider 
and extends further down on the humerus than that of the latis- 
simus dorsi. 
Action-It carries the humerus downward and backward, ro- 
tates it inward, is an inspiratory agent, and, when the humerus 
is fixed, as in climbing or using crutches, it draws the body 
upward or forward. 
Arteries and Nerves. The trapezius is supplied by the spinal 
accessory and branches from the anterior divisions of the third 
and fourth cervical. The long subscapular supplies the latissi- 
mus dorsi. The subscapular artery supplies the latissimus dorsi 
and the princeps cervicis is the chief supply of the trapezius. 
Second Layer. 
Levator Anguli Scapulae 
Rhomboideus 
Levator Anguli Scapulae. 
The levator anguli scapulae arises by tendinous slips from 
the posterior tubercles of the transverse processes of the four 
upper cervical vertebrae. These slips unite to form the belly of 
the muscle which descends obliquely outward to be inserted into 
the posterior border of the scapula from the angle to the inter- 
section of the spine with that border. 
Action-This muscle draws the shoulder upward and inward, 
or, acting from below, inclines the neck and head to that side, 
rotating them at the same time. 
Rhomboideus. 
The rhomboideus arises from the spinous processes of the 
last cervical and four upper dorsal vertebrae, and, passing down- 
ward and outward, is inserted into the posterior border of the 
scapula from the intersection of the spine with that border to 
the inferior angle. Some make two muscles of this, calling the 
portion which arises from the cervical vertebra rhomboideus 254 
DESCRIPTIVE ANATOMY. 
minor and that arising from the dorsal vertebrae rhomboideus 
major. 
Action-It moves the scapula upward and backward, so as to 
bring the two scapulae nearer together. 
Nerves. The nerve for the levator is from the anterior divi- 
sions of the third and fourth cervical. The rhomboids are sup- 
plied from the anterior division of the fifth cervical. 
Third Layer. 
Serratus Posticus Superior 
Serratus Posticus Inferior 
Splenius 
Serratus Posticus Superior. 
The serratus posticus suferior has a tendinous origin from 
the spinous processes of the two lower cervical and two upper 
dorsal vertebrae. It passes downward and outward and is in- 
serted by fleshy serrations into the upper borders of the second, 
third, fourth and fifth ribs just beyond their angles. 
Action-It is an inspiratory agent. 
Serratus Posticus Inferior. 
The serratus posticus inferior has a tendinous origin from 
the spinous processes of the last two dorsal and first two lumbar 
vertebrae. It passes upward and outward and is inserted by 
fleshy slips into the lower borders of the last four ribs. 
Action-It is an inspiratory agent. 
Splenius. 
The splenius arises from the spinous processes of the four 
lower cervical vertebrae and six upper dorsal vertebrae. It 
ascends and divides into two portions, one, known as the 
splenius capitis, is inserted into the occipital bone between its 
curved lines and into the mastoid portion and process of the 
temporal bone; the other, called splenius colli, is inserted into THE MUSCULAR SYSTEM. 
255 
the posterior tubercles of the transverse processes of the three 
upper cervical vertebrae. 
Action-It bends the head and upper part of the spine back 
and rotates the head toward its side. 
Nerves. Splenius, posterior division of cervical; serratus pos- 
ticus superior from upper, and serratus posticus inferior from 
lower dorsal nerves. 
Erector Spinae. 
This powerful muscle occupies a large portion of the verte- 
bral groove, extending from the sacrum upward until its pro- 
longation may be traced through the cervical region. It is 
held down in position, through a large portion of its course, 
by the powerful vertebral aponeurosis, called by different names 
in the different regions. In the lumbar region, where it is most 
powerful, it is continuous with the aponeurosis forming the 
sheath of the quadratus lumborum. 
The erector spinae arises by tendinous fibres from the back 
of the sacrum, occupying the whole of the sacral groove; from 
the posterior part of the crest of the ilium; from the great 
sacro-sciatic ligament and from the spinous processes of the 
lumbar vertebrae. This large mass passes upward, and, about 
opposite the last rib, it divides into two portions, the ilio-costalis, 
which is inserted into the seven lower ribs, and the longissimus 
dorsi, which is inserted into the transverse processes of the 
dorsal vertebrae and into nearly all the ribs, this portion of the 
insertion being very variable. Between these two divisions lies 
an accessory muscle, called musculus accessorius, which, aris- 
ing from the angles of the six lower, is inserted into the angles 
of its six upper ribs. Continuing this upward is the cervicalis 
ascendens, which, springing from the angles of the four upper 
ribs, is inserted into the posterior tubercles of the transverse 
processes of the fourth, fifth and sixth cervical vertebrae. In 
like manner the longissimus dorsi is continued upward by an 
inner set of fibres, the transversalis colli, which springs from 
the transverse processes of the six upper dorsal, and is in- 
serted into the cervical as high as the second; and the trachelo- 
mastoid, which, arising from the transverse processes of the 256 
DESCRIPTIVE ANATOMY. 
dorsal vertebrae from the second to the sixth, is inserted into the 
mastoid process. 
Beside these there are two small muscular masses, the 
spinalis dorsi, in the lumbar, and spinalis colli in the cervical 
region which spring from the transverse processes below and 
are inserted into those above. They are really part of the at- 
tachment of the longissiumus dorsi. The complexus is a some- 
what similar offshoot of the trachelo-mastoid arising by slips 
from the upper seven dorsal and last cervical vertebrae to be 
inserted into the occipital between the curved lines. 
Action-The name almost sufficiently gives the action of the 
erector spinae-it keeping the body in the erect posture. It can 
also bend the spine backward, or backward and to one side 
when one muscle alone acts. 
Nerves. This muscle is supplied by the posterior divisions 
of the spinal nerves in the cervical dorsal and lumbar regions. 
Beneath this layer there is another of small muscles which 
barely deserve mention. The most important being the rectus 
capitis posticus major and minor, the former springing from 
the spinous process of the axis and being inserted into the in- 
ferior curved line of the occipital; the latter arising from the 
tubercle of the atlas and being inserted into the occipital internal 
to the preceding muscle. 
The Muscles of the Thorax. 
Triangularis Sterni. 
The triangularis sterni is found on the posterior aspect of 
the front wall of the chest on either side of the sternum. It 
arises from the edge of the sternum and from the costal car- 
tilages from the third to the sixth or seventh, and, passing 
upward and outward, is inserted into the second, third, fourth 
and fifth costal cartilages and corresponding ribs. Its insertion 
corresponds to that of its antagonist, the serratus posticus 
superior. 
Action-It is an expiratory agent. THE MUSCULAR SYSTEM. 
257 
Intercostal and Levatores Costarum Muscles. 
The interval between two ribs is occupied by two layers of 
muscular fibres which extend between the edges of adjacent ribs 
and are known as external and internal intercostal muscles. 
The external intercostal muscles (eleven pairs) are attached 
to the lower border of the rib above and upper border of the rib 
below. They extend from the tubercles to the cartilages. The 
internal intercostals, also eleven pairs, are attached to the ridge 
on the inner face of the rib above and to the upper border of 
the rib below. They extend from the cartilage to the angle. 
The levatores costarum (twelve pairs) arise from the trans- 
verse process of the seventh cervical and eleven upper dorsal 
vertebrae and are inserted into the ribs between the tubercle and 
the angle. 
Nerves. 
The intercostal nerves. 
Anterior Thoracic Region. 
Pectoralis Major 
Pectoralis Minor 
Subclavius 
The muscles of this region are covered by the usual superficial 
fascia and by a deep fascia which partly blends with that of 
the cervical and, at the side, with that covering the axillary 
space. 
Pectoralis Major. 
The pectoralis major derives its name from its position on 
the front of the chest, and from the fact that there is another 
muscle smaller than it in the same region. It is coarse in struc- 
ture, triangular in shape, with its base within and apex with- 
out. It arises fleshy from the sternal two-thirds of the clavicle, 
from the whole length of the front of the sternum and from 
the cartilages of five ribs, i. e., all of true ribs except the first 
and seventh (this origin being by fibres which reinforce the 
muscle as it passes over the ribs), and from the aponeurosis of 
the external oblique muscle of the abdomen. 258 
DESCRIPTIVE ANATOMY. 
The fibres converge as they pass outward. Those from the 
clavicle pass nearly vertically downward, those from the lower 
part of the sternum and the aponeurosis of the external oblique 
pass obliquely upward and outward and the intermediate fibres 
pass horizontally outward. They all terminate in a folded ten- 
don which is inserted into the anterior bicipital ridge of the 
humerus. As the fibres are approaching their termination some 
fold over the others, those from the lower portion of the origin 
of the muscle passing behind and forming the upper part of 
the tendon, those from the clavicle passing in front and forming 
the lower part of the tendon. 
Action-It draws the humerus across the chest, slightly rotat- 
ing the arm inward. If the arm be raised it will aid the latis- 
simus dorsi in drawing it downward, or, acting from above, in 
drawing the body upward. Both it and the next muscle thus act 
as inspiratory agents. 
Pectoralis Minor. 
The pectoralis MINOR derives its name from its position on 
the front of the chest, and from the fact that there is another 
pectoral muscle of larger size. It is found beneath the pectoralis 
major, is small in size, oblique in direction and triangular in 
shape. It arises from the front of the third, fourth and fifth 
ribs, passes upward and outward, fleshy, narrows to a tendon 
and is inserted into the coracoid process of the scapula. 
Action-Rotates the scapula on the thorax and, when the 
scapula is fixed, aids in expanding the chest. 
Subclavius. 
The SUBCLAVIUS derives its name from its position just 
beneath the clavicle. It is a small round muscle which arises 
from the cartilage, and possibly the adjacent osseous portion, 
of the first rib by a tendon; it passes horizontally outward, 
becomes fleshy, and almost immediately after it ceases to rise, 
begins to be inserted, its belly being extremely short, into the 
whole length of the groove on the under surface of the clavicle. THE MUSCULAR SYSTEM. 
259 
This groove occupies about the middle one-third of the clavicle. 
Action-It draws the clavicle downward and inward. 
Nerves. The pectoral muscles are supplied by the anterior 
thoracic nerves; the subclavius by a branch from the fifth 
cervical. 
Thoracic Surgical Triangle. 
Lying just below the subclavius, which is sometimes given as 
its upper limit, is a triangular space of surgical importance. 
It is bounded above by the clavicle, below by the upper edge 
of the pectoralis minor; its apex is without and is crossed by 
the axillary vessels and nerves; its base is within and is formed 
by an imaginary line drawn from the inner extremity of the 
clavicle to the commencement of the origin of the pectoralis 
minor. 
Lateral Thoracic Region. 
Serratus Magnus. 
The SERRATUS MAGNUS is a large thin muscle found upon the 
side of the chest wall. It derives its name from its extensive 
origin by means of digitations or serrations. 
It arises by nine digitations from the outer surface of the 
eight upper ribs, the lower five interlocking with serrations of 
the external oblique. Two digitations arise from the second 
rib. Its origin is fleshy, and it continues its course, fleshy, out- 
ward and backward over the side of the chest, to be inserted 
into the whole length of the anterior edge of the posterior bor- 
der of the scapula. In this insertion the two upper digitations 
converge and their apex is inserted into the anterior face of 
the superior angle. The next two digitations have their base 
along the posterior border from near the superior to near the 
inferior angle. The remaining digitations converge and are 
inserted by the apex of the triangle into the anterior face of 
the inferior angle. 
Action-It moves the scapula on the thorax and, when the 
scapula is fixed, raises the ribs. 
Nerves. The posterior thoracic. 260 
DESCRIPTIVE ANATOMY. 
Muscles of the Upper Extremity. 
Acromial Region. 
Deltoid. 
A single muscle constitutes this region, the deltoid, so named 
from its supposed resemblance to an inverted Delta. It is a 
large, coarse muscle, triangular in outline, forming the bulge 
of the shoulder, and corresponding in a measure to the gluteus 
maximus of the lower extremity. Its base is directed upward 
and its apex downward. Its origin is extensive, consisting of 
musculo-tendinous fibres, which arise from the outer one-third 
of the anterior border of the clavicle, from the acromion pro- 
cess, and whole length of the posterior border of the spine of 
the scapula, and by some fibres from the intervening fascia 
covering the infraspinatus muscle. The fibres converge as 
they descend, the posterior passing downward and forward, the 
anterior downward and backward, and the central vertically 
downward, until they form a short, thick tendon, which is in- 
serted into a V-shaped impression about half-way down the 
outer surface of the shaft of the humerus. 
Action. Its posterior fibres carry the humerus upward and 
backward, its anterior fibres upward and forward. By its cen- 
tral fibres, which act in concert with the supraspinatus, the 
humerus is carried directly away from the body until it is at 
right angles with the body. 
Arteries and nerves. The posterior circumflex nerve and the 
circumflex arteries supply this muscle. 
The Scapular Group. 
Subscapularis 
Teres Minor 
Supraspinatus 
Infraspinatus 
Teres Major 
The scapular group of muscles consists of the sub scapular is, 
the supraspinatus, the infraspinatus, the teres major and the 
teres minor (L. Teres, long and round). Three of these muscles, THE MUSCULAR SYSTEM. 
261 
it will be seen, are named from the fossae which they occupy 
upon the scapula, the other two being named from their sup- 
posed shape, "round muscles." In the description of the scapula 
it was stated that both on the back and on the front the fossae 
described did not occupy the entire aspect of the bone, hence 
in studying the origin of these muscles it is unnecessary to 
point out the exceptions of the anterior lip of the posterior 
border for instance, but simply to except that part of the fossa 
from which the muscle fails to rise, and not that part of the 
anterior or posterior surface of the scapula. 
Subscapularis. 
The SUBSCAPULARIS, the first of these muscles, is a coarse, 
flat muscle, which occupies the entire subscapular fossa; but 
does not rise from the whole of it, nor from the whole length 
of the scapula. It rises from the entire subscapular fossa, with 
the exception of its external one-third; and also from the fas- 
cia which invests the anterior face of the muscle, and from 
septa sent down from this fascia between the bundles of mus- 
cular fibre to seize the ridges of the subscapular fossa and from 
an aponeurosis which separates it from the teres major and 
from the long head of the triceps. 
These fibres converge, the superior ones passing nearly di- 
rectly forward and outward, the central ones having a slightly 
oblique direction outward, upward and forward, while the in- 
ferior fibres run nearly directly upward and only slightly out- 
ward and forward. It narrows to a tendon, thick and strong, 
which passes over the neck of the scapula, crosses the head of 
the humerus, and is inserted into the lesser tuberosity of the 
humerus and into the bone for about an inch below, blending 
with the fibres of the capsular ligament of the shoulder joint. 
Action. It is chiefly an inward rotator of the humerus; but 
its inferior fibres have a slight effect in drawing the humerus 
downward when it has been elevated, and carrying it backward 
after it has reached the vertical position. 
Arteries and nerves. The subscapular nerve and artery sup- 
ply it. 262 
DESCRIPTIVE ANATOMY. 
Supraspinatus. 
The supraspinatus rises from the whole of the supraspinous 
fossa, except its outer one-third, and from the investing fascia, 
which completely covers the muscle. It is a triangular muscle, 
which converges as it passes forward and outward, forms a 
tendon which runs under the acromion process of the scapula, 
and which is inserted into the highest of the three muscular 
impressions found on the greater tuberosity of the humerus, the 
lower fibres of the tendon blending with the capsular ligament. 
Action. It aids the deltoid in raising, or abducting, the hu- 
merus until it is at right angles to the body; and is to a slight 
extent an outward rotator. 
Infraspinatus. 
The infraspinatus rises from the whole of the infraspinous 
fossa, except its outer third, from the investing fascia, which 
covers the muscle, and from the inter-muscular septa sent down 
near the axillary border of the scapula between itself and the 
teres major and between itself and the teres minor. Like its 
predecessor, the fibres converge to form a tendon, which, pass- 
ing behind the shoulder joint, blends with the capsular ligament, 
and is then inserted into the middle of the three muscular im- 
pressions on the greater tuberosity of the humerus. 
Action. Its action is almost entirely confined to external ro- 
tation of the humerus. 
Arteries and nerves. The suprascapular nerve and artery 
supply it and the supraspinatus. 
Teres Minor. 
The teres minor arises from the upper two-thirds of the 
axillary border of the scapula, with the exception of the space 
occupied by the long head of the triceps. It also arises from 
the inter-muscular septum between itself and the infraspinatus 
internally and itself and the teres major externally, and from 
the fascia which covers the lower portion of the muscle. Its THE MUSCULAR SYSTEM. 
263 
direction is upward and outward. The tendon narrows but 
slightly and, after blending with the fibres of the capsular liga- 
ment, is inserted into the lowest of the three muscular impres- 
sions on the greater tuberosity of the humerus, and into the 
bone for a short distance below. 
Action-Like its predecessors, its chief action is that of ex- 
ternal rotation of the humerus. 
Arteries and nerves. It is supplied by a branch from the 
circumflex nerve. The dorsalis scapulae and posterior circum- 
flex arteries supply this muscle and the following. 
Teres Major. 
The TERES MAJOR lies just below the teres minor, from which, 
after its origin, it is separated by a widening interval. It 
arises from the lower one-third of the axillary border of the 
scapula, and from that portion of the dorsum, called the inferior 
angle, which does not enter into the infraspinous fossa. It also 
arises from the investing fascia, which covers the lower portion 
of the muscle, and from inter-muscular septa between itself and 
the teres minor above and the infraspinatus behind and the 
subscapularis in front. From this origin it passes upward, out- 
ward and forward, its upward obliquity being less than that of 
the teres minor; and is inserted by a broad, flat tendon into the 
internal bicipital ridge of the humerus. 
Action. It draws the humerus downward and backward, act- 
ing here in concert with the latissimus dorsi; and is also an in- 
ward rotator. 
Arteries and nerves. It is supplied by the lower subscapular 
nerve. 
Axillary Surgical Triangle. 
Between the two teres muscles is a SURGICAL TRIANGLE of some 
importance, the base of which is directed towards the humerus, 
and the apex towards the scapula. This triangle is bounded 
above by the lower border of the teres minor, below by the 
upper border of the teres major, and externally by that portion 
of the shaft of the humerus which intervenes between the teres 264 
DESCRIPTIVE ANATOMY. 
muscles. This space is subdivided by the long head of the tri- 
seps into an external quadrilateral and an internal triangular 
space. The triangular space, of small importance, is bounded 
above by the lower border of the teres minor, below by the 
upper border of the teres major, and externally by the long 
head of the triceps. The quadrilateral space is bounded in- 
ternally by the long head of the triceps, externally by the shaft 
of the humerus, above by the lower border of the teres minor, 
and below by the upper border of the teres major. Through 
this space pass important blood-vessels and nerves. 
The Muscles and Fascia of the Humerus, or Arm. 
The muscles of the humerus, or arm, are invested by fas- 
cia, constituting a portion of the fascia of the upper extremity, 
which completely envelops the limb. In front it is continuous 
with the fascia which envelops the pectoral muscles, posteriorly 
with that which invests the posterior scapular group, internally 
with the fascia which forms the floor of the axillary space, and 
externally with the fascia investing the deltoid muscle. As this 
fascia descends the arm it sends in two septa, one from either 
side. The internal inter-muscular septum is attached to the 
internal border of the humerus, the internal condyloid ridge, 
and to the internal condyle of the humerus. The external in- 
ter-muscular septum is likewise attached to the external bor- 
der, external condyloid ridge, and external condyle of the hu- 
merus. 
These inter-muscular septa not only serve to separate the 
anterior from the posterior groups, but they also give a firm 
and unyielding origin to the various muscles of the arm and 
forearm. 
The muscles of the arm are divided into two groups: the An- 
terior and Posterior Humeral Groups. 
Anterior Humeral Group. 
Biceps Flexor Cubiti 
Coraco-Brachialis 
Brachialis Anticus THE MUSCULAR SYSTEM. 
265 
Biceps. 
The biceps (L. bis, twice; caput, head), as its name indicates, 
has a double origin, one called the "long" and the other the 
"short" head. The short head arises by musculo-tendinous fibres 
from the tip of the coracoid process of the scapula, in common 
with the coraco-brachialis. It descends blended with this mus- 
cle for its upper two inches, and then no longer blended, but 
parallel, with the coraco-brachialis, to the insertion of that mus- 
cle, where it is joined by the long head, which arises from the 
upper border of the glenoid cavity of the scapula, where it 
blends with the glenoid ligament. By tendinous fibres the long 
head passes through the shoulder joint in a separate synovial 
sheath and blends about the middle of the humerus with the 
short head to form the belly of the muscle. The belly of the 
muscle so formed passes down the front of the arm to near the 
elbow, where it terminates in a tendon, which gives off a strong 
slip of fascia to blend with the investing fascia on the inner 
front part of the forearm, while the bulk of the tendon is in- 
serted into the posterior part of the bicipital tuberosity of the 
radius. 
Action. It is a flexor of the forearm; but its short head, if 
acting alone, may to a triflling extent, adduct the arm, and the 
long head to some extent can abduct it. With the forearm in a 
position of pronation, the muscle becomes the most powerful 
of the supinators of the forearm. It is also a tensor of the deep 
fascia of the forearm. 
Nerve supply. The biceps is supplied by the musculo-cuta- 
neous nerve. 
Coraco-Brachialis. 
The coraco-brachialis arises in common with the short head 
of the biceps from the tip of the coracoid process of the scapula, 
passes down on the side of that muscle, adherent to it for about 
two inches, and then in contact with it, but no longer adherent 
to it, to the middle of the arm, where it is inserted in the mid- 
dle of the internal face of the shaft of the humerus. 266 
DESCRIPTIVE ANATOMY. 
Action. It is a flexor of the arm: and can, acting in concert 
with the short head of the biceps, aid that muscle, though acting 
more powerfully, in carrying the arm inward, or adducting it. 
Nerve supply. It is supplied by the musculo-cutaneous nerve. 
Brachialis Anticus. 
The brachialis ANTICUS (musculus brachialis) is a bulky- 
mass lying deeper than the preceding muscles on the lower 
part of the front of the arm. It arises by two digitations, so 
arranged as to embrace the V-shaped insertion of the deltoid, 
and expanding from that point down the shaft of the humerus 
to within an inch of the elbow joint, its origin covering the 
whole front of the humerus between these two points. It also 
springs from the whole of the internal inter-muscular septum, 
and from the upper portion of the external inter-muscular sep- 
tum, being cut off from the latter below by the origin of the 
supinator longus and extensor carpi radialis longior. It nar- 
rows to a triangular tendon, which passes over the elbow, and 
is inserted into the front of the coronoid process of the ulna. 
Action. It is a powerful flexor of the forearm upon the arm, 
though in some positions of the body-as in "chinning" a bar- 
it flexes the arm upon the forearm, 'acting, as all muscles do, 
from either extremity. 
Nerve supply. It is supplied by the musculo-spiral and mus- 
culo-cutaneous nerves. 
Posterior Humeral Group. 
The Triceps Extensor Cubiti. 
The triceps is a large fleshy mass. It covers the whole of 
the posterior face of the humerus, being the only muscle found 
in that situation. It rises by three heads; the middle, or long; 
the internal, or short; and the external, or intermediate. The 
long head arises from the upper one-inch of the axillary border 
of the scapula by tendinous fibres. The short head arises from 
the inner one-half of the posterior face of the humerus, and the THE MUSCULAR SYSTEM. 
267 
posterior face of the internal inter-muscular septum and the 
intermediate arises from the external half of the posterior face 
of the humerus, and the posterior face of the external inter- 
muscular septum. The three heads blend together to form the 
belly of the muscle, which, passing downward, becomes ten- 
dinous, the tendinous fibres extending much further up on its 
posterior than on its deep, or anterior, aspect, to be ultimately 
inserted into the depressed surface on the back part of the 
upper extremity of the olecranon process of the ulna. 
The muscle can be more briefly described by saying that the 
inner and the external of the heads rise from the whole of the 
posterior surface of the shaft of the humerus, and from the 
whole of the posterior surface of the internal and external inter- 
muscular septa, the former beginning at the insertion of the 
teres major and the latter at the insertion of the teres minor. 
Between these is found the long head, arising at the upper inch 
of the axillary border of the scapula. They all blend to reach 
the insertion above mentioned. 
Action.-This muscle is the extensor of the forearm upon the 
arm; but its long head being attached to the scapula and pass 
ing over tw7o joints, approximates the head of the humerus to 
the glenoid cavity, and slightly aids other muscles in drawing 
the humerus backward. It may also, in climbing, draw the 
scapula, and if that be fixed, the body, upward on the humerus. 
Nerve supply. It is supplied by the musculo-spiral nerve. 
The Fascia of the Forearm. 
Before reaching the muscles of the forearm we find that por- 
tion of the upper extremity enveloped in a strong fibrous mem- 
brane, call the Deep or Investing Fascia of the Forearm. 
This membrane, which is continuous with the investing fascia 
of the forearm, is first attached to the olecranon process of the 
ulna and passes downward attached to the posterior border of 
the shaft of the ulna. Passing forward on either side, it is at- 
tached to the internal and external condyles of the humerus, 
and then uniting over the front of the limb, forms a complete 
investment. From this investing sheet septa are sent off, which 268 
DESCRIPTIVE ANATOMY. 
not only serve the purpose of dividing the different layers from 
one another, but which also serve to give a strong and firm at- 
tachment to the muscles which belong to this portion of the 
upper extremity. Some of these muscles arise from the invest- 
ing membrane, while others arise from the intermuscular septa, 
which are tongues of fascia sent down between the different 
muscles or groups of muscles. Thus the whole limb is divided 
into separate compartments, so that could a muscle be dissolved 
out without affecting the fascia, it would be found to have its 
separate and distinct compartment, as would be the case for all 
of the muscles of the limb. This fascia becomes particularly 
strong and dense at the wrist joint, where it sends across both 
on the front and the back strong braces, which are respectively 
known as the anterior and posterior annular ligaments. 
The posterior is an oblique band, which passes downward and 
inward across the back of the wrist, and is attached by one ex- 
tremity to the lower end and styloid process of the radius, and 
by the other to the lower end of the ulna, the cuneiform and 
pisiform bones. It binds the extensor tendons down upon the 
bones, and sends down septa, which form six separate compart- 
ments through which these tendons pass. 
The anterior annular ligament is less well marked than is the 
posterior. It is attached by one extremity to the front of the 
scaphoid and trapezium; by the other extremity it is attached 
to the pisiform bone, sending off a process which becomes at- 
tached to the unciform process of the unciform bone. 
The Muscles of the Forearm. 
The MULES OF the forearm are divided into those on the 
front and those on the back; and these are again subdivided by 
intermuscular septa into a superficial and deep group on the 
front of the forearm, and into three groups-external or radial, 
superficial, and deep-on the back. It must be borne in mind 
that every muscle found upon the front of the forearm is to 
produce either flexion or pronation, and that every muscle upon 
the back of the forearm produces either extension or supination. 
Hence the names of the muscles upon the front will be either THE MUSCULAR SYSTEM. 
269 
flexor or pronator, on the back either extensor or supinator; 
and to these names are added the particular function of the 
muscle, as a flexor of the radial side of the carpus or an ex- 
tensor of the radial side of the carpus. 
The Muscles of the Front of the Forearm. 
The muscles of the front are eight in number, and are di- 
vided into two layers, of which the superficial contains five mus- 
cles and the deep three. The superficial muscles on the front of 
the forearm have a common tendon, the origin of which tendon 
is from the inner condyle of the humerus, the investing fascia 
which covers the muscle, and the intermuscular septa which 
are sent down between the muscular fibres. In addition to this, 
many muscles have other points of origin. The superficial mus- 
cles of the back of the forearm likewise have a common tendon, 
which arises from the external condyle of the humerus, the in- 
vesting fascia, and the intermuscular septa. 
First or Superficial Layer. 
Pronator Radii Teres 
Palmaris Longus 
Flexor Carpi Radialis 
Flexor Carpi Ulnaris 
Flexor Sublimis Digitorum 
Pronator Radii Teres. 
The PRONATOR radii teres is the first muscle of the super- 
ficial group. It takes its origin from the common origin, the 
internal condyle of the humerus, from the investing fascia which 
covers it and from an intermuscular septum between itself and 
the flexor carpi radialis. In addition to this, there is a small 
or deep head of this muscle, which arises from the inner face 
of the coronoid process of the ulna, these two heads being sepa- 
rated by the median nerve. The two heads unite after a short 
course, and passing downward and outward, wind around the 
shaft of the radius, and are inserted into the middle one-third 
of the outer surface of the shaft of the radius. 270 
DESCRIPTIVE ANATOMY. 
Flexor Carpi Radialis. 
The flexor carpi radialis is the second muscle of the superfi- 
cial group. It arises from the common origin-the internal 
condyle of the humerus and investing fascia, and two intermus- 
cular septa, one between itself and the pronator radii teres and 
the other between itself and the palmaris longus. It is a long 
and slender muscle, which passes downward, with a slight in- 
clination outward for the upper one-third of the forearm. The 
muscular belly then changes into a tendon, which, running ver- 
tically downward, passes through a groove in the trapezium, and 
is inserted into the base of the metacarpal bone of the index 
finger. 
Palmaris Longus. 
The palmaris LONGUS arises from the common origin-the 
internal condyle, the investing fascia, and the intermuscular 
septa, between itself and the flexor carpi radialis on one side 
and the flexor sublimis digitorum on the other. It is a small 
and very slender muscle, which, passing straight down the 
middle of the front of the forearm, soon becomes tendinous and 
is inserted into the palmar fascia chiefly, but partly into the 
anterior annular ligament. The muscle should be called the 
"middle flexor of the carpus." 
Flexor Carpi Ulnaris. 
The flexor CARPI ulnaris arises from the common origin-in- 
ternal condyle, the investing fascia, and the intermuscular septa 
between itself and the flexor sublimis digitorum. It also arises 
by an aponeurosis from the inner side of the olecranon process 
and from the upper two-thirds of the posterior border of the 
ulna. This muscle remains fleshy until within two inches of 
the wrist joint. It then becomes tendinous and is inserted into 
the base of the metacarpal bone of the little finger, its tendon 
enclosing the pisiform as a sesamoid bone. THE MUSCULAR SYSTEM. 
271 
Flexor Sublimis Digitorum. 
The flexor sublimis digitorum lies beneath the preceding 
muscles of the group, and is in contact with the investing fascia 
for only a small portion of its course, frequently not touching 
that fascia at all. It arises from the inner condyle of the hu- 
merus, investing fascia, and intermuscular septa; also from the 
internal lateral ligament of the elbow, from the base of the 
coronoid process of the ulna, and from the oblique line of the 
radius for about two-thirds of that line. It descends beneath 
the superficial layer of muscles, and at the lower third of the 
forearm divides into four tendons. These tendons, enclosed in 
a synovial sheath, enter the hand by passing beneath the an- 
terior annular ligament, and then, separating from one another, 
pass forward to each finger to be inserted into the sides of the 
shaft of the second phalanx of each of the four lesser fingers. 
At the base of the first phalanx each tendon splits, and through 
this opening the tendon of the deep flexor passes. The super- 
ficial tendons then unite and form a groove, in which the tendon 
of the deep flexor lies. They then split a second time to be in- 
serted into the sides of the second phalanges. 
Second or Deep Layer. 
Flexor Profundus Digitorum. 
Pronator Quadratus. 
Flexor Longus Pollicis. 
Flexor Profundus Digitorum. 
The flexor profundus digitorum lies just beneath the sub- 
limis and to the ulnar side of the longus pollicis. It arises from 
the upper two-thirds of the anterior and inner faces of the ulna; 
by a strong aponeurosis from the posterior border of the ulna, 
where it blends with the flexor carpi ulnaris; and from the ulnar 
part of the interosseous membrane. 
It divides into four tendons, which enter the palm of the 
hand and, separating, run one to each of the fingers, pierce the 272 
DESCRIPTIVE ANATOMY. 
tendons of the superficial flexor at the base of the fingers, and 
are inserted into the base of the last phalanx. 
Flexor Longus Pollicis. 
The flexor longus pollicis lies to the outer side of the pre- 
ceding muscle. It arises from about the middle two-fourths of 
the front of the radius and from the radial side of the interos- 
seous membrane. It passes downward and, becoming tendinous, 
runs beneath the anterior annular ligament, passes between the 
two heads of the flexor brevis pollicis and is inserted into the 
base of the last phalanx of the thumb. 
Pronator Quadratus. 
The pronator quadratus occupies the lower fourth of the 
forearm and thus prevents the origin of the preceding muscles 
for that distance. It arises from the inner side of the ulna, re- 
ceiving some fibres from the front of that bone as it passes 
over it, and is inserted into the front of the radius as far as 
the outer side. 
Flexor Tendons of the Fingers. 
It has been seen that the tendons of the flexor sublimis digi- 
torum split at the base of the fingers to allow the passage of 
the tendons of the flexor profundus, unite and again split to 
be inserted into the sides of the shaft of the second phalanx of 
each finger. Before its insertion each tendon gives off thread- 
like prolongations, called vincula accessoria, which are inserted 
into the sides of the bones; and both tendons are bound down 
to the bones by transverse bands of ligamentous fibres called the 
thecae. 
Arteries and Nerves. The muscles on the outer side of the 
forearm are supplied by branches from the radial artery; those 
on the inner side from the ulnar. All of the muscles on the 
front of the forearm are supplied by the median nerve or one 
of its branches, except the flexor carpi ulnaris and the inner 
one-half of the flexor profundus digitorum. The branch of the THE MUSCULAR SYSTEM. 
273 
median which supplies the deep muscles is called the anterior 
interosseous; the nerve supplying the flexor carpi ulnaris and 
the inner half of the flexor profundus digitorum is the ulnar. 
Action of the Muscles of the Forearm. 
The name indicates the action of each of these muscles, but 
indicates only a portion of the action. 
The pronator radii teres is first a pronator, of the hand; but 
after having acted to its fullest extent as a pronator, it then be- 
comes, in common with the other muscles of the group, a flexor 
of the forearm upon the arm. 
The flexor carpi radialis, palmaris longus-, and flexor carpi ul- 
naris are primarily flexors of the wrist; but the palmaris longus 
in addition is a tensor of the palmar fascia, and all three flex 
the forearm upon the arm. 
The flexor sublimis digitorum flexes the second phalanx on 
each of the four lesser fingers. Having effected this, it will flex 
the first phalanx upon the hand; continuing to act, it flexes the 
hand upon the wrist; and acting still further, it flexes the fore- 
arm upon the arm. 
The flexor longus pollicis flexes the last phalanx of the thumb; 
then the first upon the metacarpal bone of the thumb; then the 
metacarpal bone upon the hand, and the hand upon the wrist, 
and the wrist upon the forearm. 
The flexor profundus digitorum flexes the last phalanx upon 
the second, but cannot do this until a superficial flexor first has 
flexed the second. Continuing its action, it will act in concert 
with and like the superficial flexor. 
Interosseous Membrane. 
The interosseous membrane, mentioned above, is a strong 
fibrous membrane stretched between the two bones. It econo- 
mizes weight, while it furnishes as stable an origin for muscles 
as does bone. 274 
DESCRIPTIVE ANATOMY. 
Posterior Region. 
The muscles upon the back of the forearm also have a com- 
mon origin, viz: external condyle of humerus, investing fascia 
and intermuscular septa. 
They are divided into three groups, called radial, superficial 
and deep groups, each containing four muscles. These muscles 
are either extensors or supinators, acting in opposition to those 
on the front of the forearm. 
Radial Group. 
Supinator Longus 
Extensor Carpi Radialis Longior 
Extensor Carpi Radialis Brevior 
Supinator Longus. 
The supinator LONGUS (brachio-radialis) derives its name 
from the fact that it is a supinator of the forearm and that 
there is another supinator called brevis. 
It arises from the upper two-thirds of the external condyloid 
ridge and from the corresponding part of the external inter- 
muscular septum, and, after descending about one-half of its 
course, terminates in a tendon which is inserted into the outer 
side of the base of the styloid process of the radius. 
Extensor Carpi Radialis Longior. 
The EXTENSOR CARPI radialis LONGIOR derives its name from 
the action of the muscle and from the fact that there is another 
radial extensor which is shorter. It arises from the lower one- 
third of external condyloid ridge and from the corresponding 
part of the external inter-muscular septum, and descends to be 
inserted by its tendon into the base of the metacarpal bone of the 
index finger, after passing under the posterior annular ligament. THE MUSCULAR SYSTEM. 
275 
Extensor Carpi Radialis Brevior. 
The EXTENSOR carpi radialis BREVIOR, deriving its name from 
the facts stated with the preceding muscle, arises from the com- 
mon origin, which is the external condyle, the investing fascia 
and an inter-muscular septum between itself and the extensor 
communis digitorum. It passes downward between the extensor 
carpi radialis longior and the extensor communis digitorum, 
crosses beneath the tendons of the extensor ossis metacarpi polli- 
cis and extensor primi internodii pollicis, as does the preceding 
muscle, before passing under the posterior annular ligament, 
then passes beneath the tendon of the extensor secundi inter- 
nodii pollicis and is inserted into the radial side of the base of 
the third metacarpal bone. This muscle and the extensor carpi 
radialis longior, lie in the same groove while passing under the 
annular ligament. 
Back of Forearm-Superficial Group. 
Extensor Communis Digitorum 
Extensor Carpi Ulnaris 
Extensor Minimi Digiti 
Anconeus 
Extensor Communis Digitorum. 
The extensor communis digitorum derives its name from 
its action as the extensor common to the four fingers. It arises 
from the common origin, external condyle investing fascia and 
two inter-muscular septa, one between itself and the extensor 
carpi radialis brevior externally, and one between itself and 
the extensor minimi digiti internally. Passing down the back 
of the forearm the muscle divides into three tendons, which 
pass beneath the annular ligament in a compartment with the 
extensor indicis. On reaching the back of the hand the inner- 
most tendon divides into two; and the four tendons, thus 
formed, pass to the four lesser fingers, and are inserted into 
the backs of the four lesser fingers after the manner of extensor. 
This expression means that opposite the metacarpo-phalangeal 
joint each tendon becomes narrower and receives the tendon 276 
descriptive anatomy. 
of the lumbricales. Passing to the shaft, each tendon becomes 
broader and thinner. Upon reaching the phalangeal joints each 
becomes thicker and furnishes a posterior ligament for those 
joints. The tendon to the ring finger is usually bound by slight 
bands to the tendons of the little and middle fingers. 
Extensor Minimi Digiti. 
The extensor minimi digiti is an offshoot of the common ex- 
tensor and, as its name indicates, has for its function the ex- 
tension of the little finger. It arises from the common origin 
(external condyle, investing fascia and septa between itself 
and the extensor communis externally and the extensor carpi 
ulnaris internally) and is inserted into the whole length of the 
back of the little finger, along with the slip furnished that 
finger by the common extensor, after the manner of extensor 
tendons. 
This muscle is really an offshoot of the common extensor. 
Its claim to individuality's that it has a separate compartment 
in the annular ligament. 
Extensor Carpi Ulnaris. 
The extensor carpi ulnaris derives its name from its action 
as an extensor of the hand and from its situation on the ulnar 
side of the forearm. It arises from the common origin (ex- 
ternal condyle, investing fascia and the inter-muscular septa 
between itself and the extensor minimi digiti externally and the 
deep group in front) and, by a strong aponeurosis, which blends 
with that giving origin to the carpal flexor, from the middle 
third of the posterior border of the ulna. The muscle re- 
mains fleshy until just above the wrist joint when it becomes 
tendinous and, passing through a groove on the back of the 
styloid process of the ulna, in its own compartment in the an- 
nular ligament, is inserted into the base of the metacarpal bone 
of the little finger on its ulnar side. THE MUSCULAR SYSTEM. 
277 
Anconeus. 
The anconeus is a small triangular muscle which arises by 
its apex from the external condyle of the humerus, and is in- 
serted by its base into the olecranon process and triangular 
surface at the upper extremity of the ulna. It is really an 
offshoot of the triceps extensor, and its action is to aid that 
muscle in extending the forearm on the arm. 
Deep Group. 
The five muscles of this group lie beneath those of the super- 
ficial group, and all arise from the interosseous membrane as 
one attachment. As indicated by their names, they are all 
extensors, three being appropriated by the thumb and one by 
the index finger. 
Supinator Brevis. 
Extensor Ossis Metacarpi 
Pollicis. 
Extensor Primi Internodii 
Pollicis. 
Extensor Secundi Internodii 
Pollicis. 
Extensor Indicis. 
Supinator Brevis. 
The supinator brevis is a thin flat muscle which encircles 
the upper third of the radius. 
It arises from the external condyle of the humerus, the ex- 
ternal lateral and orbicular ligaments, from the triangular de- 
pressed surface beneath the lesser sigmoid cavity of the ulna, 
and to some extent from the inter-muscular septum between 
the deep and superficial groups. It winds outward around the 
radius and is inserted into the upper third of its oblique ridge. 278 
descriptive anatomy. 
Extensor Ossis Metacarpi Pollicis. 
The extensor ossis metacarpi pollicis (abductor pollicis 
longus) arises from the radius, ulna, interosseous membrane, 
and a fibrous septum between it and the extensor primi. Its 
upper attachment to both bones is limited by the supinator 
brevis. It becomes tendinous and winding around the radius 
crossing the tendons of the extensor carpi radialis longior and 
brevior, and passing through the annular ligament, is inserted 
into the base of the metacarpal bone of the thumb. 
Extensor Primi Internodii Pollicis. 
The extensor primi internodii pollicis (extensor brevis pol- 
licis) arises from the radius for about its middle two-fourths and 
interosseous membrane. After becoming tendinous it follows 
the extensor ossis metacarpi pollicis, lying internal to that 
muscle, crosses the same tendons, passes through the next 
groove on the radius, and is inserted into the base of the first 
phalanx of the thumb. 
Extensor Secundi Internodii Pollicis. 
The extensor secundi internodii pollicis (extensor longus 
pollicis) arises from the ulna for about its middle third and 
from the interosseous membrane. Its tendon passes through 
a separate compartment in the annular ligament, crosses the 
tendons of the extensor carpi radialis longior and brevior after 
passing through the annular ligament, and is inserted into the 
base of the last phalanx of the thumb. 
Extensor Indicis. 
The extensor indicis arises from the ulna and interosseous 
membrane, and is inserted into the whole length of the back 
of the index finger, blending with the tendon furnished that 
finger by the common extensor. It passes through the annular THE MUSCULAR SYSTEM. 
279 
ligament in a compartment common to it and the extensor com- 
munis digitorum. 
Action-The names of these muscles in a large measure indi- 
cate their action. A carpal extensor extends the hand and 
draws it to its own side. The radial and ulnar extensors, act- 
ing together, bend the hand straight backward. The extensors 
of the fingers bend the fingers backward and then extend the 
hand at the wrist. Of the supinators the brevis is the stronger. 
It is only when the hand is in full pronation that the supinator 
longus acts to produce supination. With the hand in full supi- 
nation it becomes- a pronator. It may also act as a flexor of the 
forearm upon the arm. 
Arteries and Nerves. The supinator longus and extensor 
carpi radialis longior are supplied by the musculo-spiral nerve; 
the others by the posterior interosseous. The posterior inter- 
osseous artery supplies these muscles. 
The Muscles of the Hand. 
The central portion of the palm of the hand is depressed be- 
low the level of a prominence on either side, one extending- from 
the base of the little finger toward the wrist, called the hypo- 
thenar eminence, and the other, considerably more prominent, 
extending upward from the base of the first phalanx of the 
thumb toward the wrist, called the thenar eminence. 
When the skin has been removed a thick layer of fatty tissue 
is exposed, which serves as a protection for the vessels and 
nerves in grasping with the hand, and beneath this is a strong 
fascia called the palmar fascia. It has a thick central portion 
and two thinner lateral portions which cover the muscles form- 
ing the thenar and hypothenar eminences. Tracing this fascia 
to the wrist, it is found to be continuous with a strong fibrous 
band, which extends across the wrist from one side to the 
other, binding down the tendons which pass beneath it, and 
known as the anterior annular ligament. 
The muscles of the hand consist of two groups, the thenar 
and hypothenar groups, and four small muscles found in the 
depressed portion of the hand, called lumbricales. 280 
DESCRIPTIVE ANATOMY. 
Thenar Group. 
Abductor Pollicis. 
Flexor Ossis Metacarpi Pollicis. 
Flexor Brevis Pollicis. 
Adductor Obliquus Pollicis. 
Adductor Transversus Pollicis. 
The muscles of the thenar group are appropriated to the 
thumb, the movements of which are as follows: (a) abduction, 
or movement of the thumb outward from the index finger. 
(b) adduction, a movement in the opposite direction. (c) 
flexion, in which the thumb is put in contact with the pulp of 
any of the fingers. This is effected by putting in motion the 
metacarpal bone of the thumb by a muscle called opponens. 
(d) extension, movement in the opposite direction effected by 
muscles on the back of the forearm, which have been described. 
Abductor Pollicis. 
The abductor pollicis arises from the trapezium bone and 
anterior annular ligament, and is inserted in the outer side of 
the base of the first phalanx of the thumb. 
Flexor Ossis Metacarpi Pollicis. 
The flexor ossis metacarpi pollicis, or the opponens pol- 
licis, arises from the trapezium bone and anterior annular liga- 
ment, and is inserted into the whole length of the radial border 
of the metacarpal bone of the thumb. 
Flexor Brevis Pollicis. 
The flexor brevis pollicis consists of two parts, one of 
which, the superficial portion, arises from the trapezium bone 
and annular ligament, and the other, or deep portion, from 
the inner side of the first metacarpal bone. It is inserted into 
both sides of the base of the first phalanx of the thumb, its 
tendons of insertion having sesamoid bones in them. THE MUSCULAR SYSTEM. 
281 
Adductor Obliquus Pollicis. 
The adductor obliquus arises from the trapezium, trapezoid, 
os magnus and base of the third metacarpal bone. It is in- 
serted into the inner side of the base of the first phalanx of the 
thumb along with the transverse head. 
Adductor Pollicis. 
The adductor pollicis (adductor transverse pollicis) is a 
flat triangular muscle which arises by its base from the whole 
length of the front of the metacarpal bone of the middle finger. 
It is inserted into the inner side of the base of the first phalanx 
of the thumb. 
Hypothenar Group. 
Palmaris Brevis. 
Flexor Brevis Minimi Digiti. 
Abductor Minimi Digiti. 
Opponens Minimi Digiti. 
Palmaris Brevis. 
The palmaris brevis is a small pale muscle lying just be- 
neath the skin of the palm. It arises from the palmar fascia 
and the anterior annular ligament, and passing inward, about 
an inch wide, is inserted into the skin on the inner border of 
the hand. 
Abductor Minimi Digiti. 
The ABDUCTOR MINIMI digiti arises from the pisiform bone 
and anterior annular ligament, and is inserted into the inner 
side of the base of the first phalanx of the little finger. 
Action-It is an abductor of the little finger, i. e., draws the 
little finger inward away from the ring finger. 
Flexor Brevis Minimi Digiti. 
The flexor brevis minimi digiti arises from the unciform 
process of the unciform bone and the anterior annular liga- 282 
DESCRIPTIVE ANATOMY. 
ment, and is inserted into the base of the first phalanx of the 
little finger. 
Action-It is a flexor of the little finger. 
Opponens Minimi Digiti. 
The Opponens minimi digiti arises from the unciform process 
of the unciform bone and the anterior annular ligament, and is 
inserted into the whole length of the metacarpal bone of the 
little finger. 
Action-It draws the metacarpal bone of the little finger 
outward and forward, carrying the little finger towards the 
thumb. 
The Lumbricales. 
The lumbricales are four small muscles which arise from 
the tendons of the deep flexor of the fingers. Winding around 
the radial side of each metacarpo-phalangeal articulation, they 
are inserted into the expanded tendons of the extensor com- 
munis digitorum. 
The Interossei. 
The DORSAL - INTEROSSEI, four in number, arise from the 
borders of the adjacent metacarpal bones, their fibres having a 
bipenniform arrangement, and are inserted into the bases of the 
first phalanges and into the common extensor tendons. The first 
dorsal interosseous is often called the abductor indicis. It arises 
from the metacarpal bones of the thumb and index fingers and 
is inserted into the first phalanx of the index finger. The second 
and third are both inserted into the first phalanx of the middle 
finger, one on the radial and the other on the ulnar side. The 
fourth is inserted into the ulnar side of the first phalanx of the 
ring finger. 
The palmar interossei, three in number, arise from the 
palmar aspect of the second, fourth and fifth metacarpal bones 
and are inserted into the base of the first phalanx of the cor- 
responding fingers. The first lies on the ulnar, the other two 
on the radial side of those fingers. THE MUSCULAR SYSTEM. 
283 
Arteries and Nerves. The superficialis volae and branches 
of the palmar arch supply the muscles of the palm. The median 
nerve supplies the outer two lumbricales and all the muscles 
of the thenar group except the deep head of the flexor brevis 
pollicis and the adductor pollicis, which are supplied by the 
deep branch of the ulna. The ulnar nerve supplies the inner 
two lumbricales, the interossei, and the hypothenar group and 
the adductor pollicis and the deep head of the flexor brevis 
pollicis. 
Muscles and Facias of the Lower Extremity. 
The MUSCLES of the lower extremity are divided into those of 
the hip, thigh, leg and foot. The hip is called the gluteal region. 
As in the upper extremity, the muscles are here covered by 
an investing fascia, which is much thicker and stronger than 
in the former situation, known in the thigh as the fascia lata 
or vagina femoris. It lies just beneath the skin and superficial 
fascia, and is a strong, thick, fibrous membrane which, de- 
scending to the knee, invests that joint and passes on to become 
the investing fascia of the leg. From the hip to the knee it is 
known by three names, investing fascia of the thigh, vagina 
femoris, or generally, fascia lata. It not only forms a firm 
resisting covering for the muscles, but sends in septa between 
the groups. Two of these septa, attached to the lips of the 
linea aspera, are known respectively as the external and inter- 
nal inter-muscular septa. The external inter-muscular septum lies 
between the anterior and posterior femoral groups, and gives 
origin to muscles of both groups. The internal lies between 
the anterior and internal groups, no strong septum being inter- 
posed between the internal and posterior groups. Above, this 
fascia is continuous, on the front of the thigh, with Poupart's 
ligament, externally and posteriorly with the fascia covering 
the gluteal muscles, while internally it is attached to the tuber- 
osity of the ischium and to the ischio-pubic ramus. Below it 
seizes the bony prominences around the knee-joint and becomes, 
posteriorly, the popliteal fascia, which covers in the popliteal 
space. 284 
DESCRIPTIVE ANATOMY. 
The fascia lata consists of two layers between which are 
found three muscles of the thigh forming the superficial 
femoral group. It is thinner over the posterior femoral region 
than in any other portion of its course. 
The Gluteal Region. 
The muscles of the gluteal region, nine in number, are ar- 
ranged in three layers, each of which has a muscle called gluteus. 
First Layer. 
Gluteus Maximus. 
The GLUTEUS MAXIMUS is a quadrilateral muscle, the largest 
and coarsest in the body, and forms the bulge of the buttock. 
It arises from the posterior fifth of the crest of the ilium, from 
the dorsum ilii between the superior curved line and the crest, 
from the posterior surface of the sacrum and coccyx, from 
the greater sacro-sciatic ligament and from the fascia covering 
the gluteus medius. It passes obliquely downward and out- 
ward to be inserted into the line leading from the trochanter 
major to the linea aspera and into the fascia lata. The upper 
and thicker portion of the fibres, forming more than half the 
muscle, are inserted into the fascia lata. A large bursa is in- 
terposed between this muscle and the trochanter major. 
Action-It is an abductor, and extensor and an outward 
rotator of the thigh, a tensor of the fascia lata and steadies 
the pelvis on the femur. 
It is supplied by the inferior gluteal nerve. 
Second Layer. 
Gluteus Medius. 
Gemellus Inferior. 
Pyriformis. 
Obturator Internus. 
Quadratus Femoris. 
Gemellus Superior. THE MUSCULAR SYSTEM. 
285 
Gluteus Medius. 
The gluteus medius is partially covered by the gluteus maxi- 
mus. It arises from the anterior four-fifths of the crest of the 
ilium, except the anterior one inch, from the dorsum ilii be- 
tween the superior and middle curved lines and from the in- 
vesting fascia, which covers its. outer front part. It passes 
downward, the anterior fibres inclining backward, the posterior 
fibres inclining forward. It is inserted into the anterior part 
of the outer surface of the trochanter major. On its outer edge 
the muscle is continuous with the gluteus maximus. 
Action-Its greater power is shown in abduction; but its 
anterior fibres can rotate the femur inward while the posterior 
rotate it outward. It can twist the pelvis on the femur, draw- 
ing the body to that side. It steadies the pelvis on the femur 
and can draw the limb forward in walking. 
It is supplied by the superior gluteal nerve. 
Pyriformis. 
The PYRIFORMIS is a pear-shaped muscle. It arises within the 
pelvis by three fleshy slips interposed between the anterior sacral 
foramina from the first to the fourth and from the adjoining 
part of the ilium. It escapes from the pelvis through the greater 
sacro-sciatic foramen, passes downward and outward, and is 
inserted into the posterior border of the upper extremity of the 
trochanter major, or into the digital pit. 
Action-It is an external rotator of the thigh. 
The Gemelli. 
The gemelli are a pair of small muscles lying one above and 
the other below the tendon of the obturator internus. 
The gemellus superior arises from the spine of the ischium 
runs horizontally outward and is inserted into the digital pit 
of the trochanter major. 286 
DESCRIPTIVE ANATOMY. 
The gemellus inferior arises from the tuberosity of the 
ischium, passes horizontally outward and is inserted into the 
digital fossa. 
Action-Both are outward rotators of the thigh. 
Obturator Internus. 
The OBTURATOR INTERNUS arises within the pelvis from the 
inner surface of the obturator membrane, from the margin of 
the obturator foramen and from the inclined plane of the 
ischium. Its course is downward and slightly backward until, 
becoming1 tendinous, it escapes from the pelvis through the 
lesser sacro-sciatic foramen, and, passing horizontally outward, 
its tendon winding, in a right angle, around the posterior border 
of the ischium just below the spine, it is inserted into the digital 
fossa of the trochanter major. 
Action-It is an outward rotator of the thigh. 
Quadratus Femoris. 
The QUADRATUS FEMORIS, as its name indicates, is a square 
muscle which lies below the tendon of the obturator intemus. 
It arises from the outer lip of the tuberosity of the ischium, 
and is inserted vertically across the posterior inter-trochanteric 
line. Its insertion is rarely marked by the presence of the linea 
quadrati. 
Action-It is an outward rotator of the femur. 
These muscles are all supplied by branches coming1 directly 
from the sacral plexus. 
Third Layer. 
Gluteus Minimus. 
Obturator Externus. 
Gluteus Minimus. 
The gluteus minimus lies beneath the gluteus medius and 
maximus. It is a triangular radiated muscle which arises from THE MUSCULAR SYSTEM. 
287 
the dorsum ilii between the middle and inferior curved lines. It 
passes down, narrowing as it descends, and is inserted into the 
anterior border of the trochanter major. In front, it is continu- 
ous with the gluteus medius. 
Action-It is an abductor and inward rotator of the thigh. 
Acting from below it steadies the pelvis on the femur. 
It is supplied by the superior gluteal. 
Obturator Externus. 
The obturator externus arises from the inner two-thirds 
of the outer surface of the obturator membrane and from the 
inner margin of the obturator foramen. It narrows to a tendon, 
which, passing outward behind the neck of the femur, is in- 
serted into the digital pit of the trochanter major. It lies on 
the capsular ligament of the hip-joint. 
Action-It is an external rotator of the thigh. 
It is supplied by the obturator nerve. 
The Femoral Region. 
The muscles of this region are divided into four groups: pos- 
terior, superficial, anterior and internal. Of these groups the 
superficial is enclosed between the two layers of the fascia lata, 
the anterior is separated from the posterior and internal by 
the two inter-muscular septa, while the internal and posterior 
are in contact. 
Posterior Femoral Region. 
Biceps Flexor Cruris. 
Semitendinosus. 
Semimembranosus. 
Biceps Flexor Cruris. 
The biceps, as its name imports, arises by two heads. The 
long head springs, in common with the semitendinosus, from 
the tuberosity of the ischium and descends adherent to the 288 
DESCRIPTIVE ANATOMY. 
semitendinosus for several inches. It then accompanies the 
semitendinosus, but no longer adherent to it, to the lower third 
of the thigh; is joined by the short head which arises from the 
whole length of the outer lip of the body of the linea aspera 
and from the posterior face of the external intermuscular 
septum. The muscle thus formed after descending to the lower 
third of the femur in contact with the semitendinosus, leaves 
that muscle and makes for the outer side of the knee-joint, 
where it is inserted chiefly into the head of the fibula, but sends 
some fibres to the outer tuberosity of the tibia and some to 
the fascia of the leg. 
Semitendinosus. 
The semitendinosus arises in common with the long head 
of the biceps, adheres to it for several inches, and then descends 
in contact with it to the lower third of the thigh, where it 
leaves the biceps and passes to the inner aspect of the knee- 
joint, where it is inserted into the inner surface of the shaft 
of the tibia, below the inner tuberosity, sending a slip to the 
fascia of the leg. This is known as the "goose foot" insertion. 
It is made up of three muscles, viz.: semitendinosus, sartorius, 
and gracilis. 
Semimembranosus. 
The semimembranosus arises from the tuberosity of the 
ischium just in front of and external to the preceding muscles, 
and descends, in company with them, to the lower third of the 
femur, whence it accompanies the semitendinosus to the inner 
side of the knee-joint and receives a threefold insertion, viz.: 
into the horizontal groove on the inner tuberosity of the tibia, 
into the fascia covering the popliteus muscle, and into the pos- 
terior ligament of the knee-joint. 
These three muscles are spoken of as the hamstring muscles, 
the biceps being the outer, the semimembranosus and semi- 
tendinosus being the inner hamstrings. 
Action-It will be seen that these three muscles all pass over 
two joints. They are, of course, all flexors of the leg upon the THE MUSCULAR SYSTEM. 
289 
thigh; but, in addition, the biceps has a slight influence in 
rotating the leg outward and the others in rotating it inward. 
After flexing the leg upon the thigh, they can then extend the 
thigh upon the pelvis. When acting from below they draw the 
pelvis downward and backward, keeping the body from falling 
forward, or aid in restoring it to the erect posture after bend- 
ing forward. 
The great sciatic nerve supplies the group. 
Superficial Femoral Group. 
Tensor Fasciae Femoris. 
Gracilis. 
Sartorius. 
Tensor Fasciae Femoris. 
The tensor fasciae femoris is a short flat muscle found 
lying on the outer aspect of the thigh between the two layers 
of the fascia lata. It arises from the outer lip of the crest of 
the ilium near the anterior superior spinous process and blend- 
ing with the anterior border of the gluteus medius, descends 
with an inclination backward, and is inserted into the fascia 
lata about one-fourth down the thigh. 
Action-It is a tensor of the fascia lata, and aids in rotating 
the limb inward. 
Sartorius. 
The sartorius is the longest muscle in the body. It arises 
from the anterior superior spinous process of the ilium and half 
the notch below, passes obliquely downward and inward across 
the upper third of the thigh, then descends vertically behind the 
internal condyle of the femur, and then turns obliquely forward 
and outward to be inserted into the upper inner face of the 
tibia below the internal tuberosity, sending a slip to the fascia 
of the leg. It forms one of the elements of the "goose foot" 
insertion, the other two being the semitendinosus and gracilis. 
The sartorius is the most superficial at the insertion, then the 
gracilis and the semitendinosus is the deepest. 290 
DESCRIPTIVE ANATOMY. 
Action-It flexes the thigh on the pelvis, the leg on the thigh, 
and carries it inward across its fellow. It may, acting from 
below, twist the pelvis so as to carry the front of the body 
towards the opposite side. 
Gracilis. 
The gracilis arises by a thin broad aponeurosis from the 
edge of the symphysis pubis and from the margin of the ischio- 
pubic ramus. It soon becomes fleshy and passes down the inner 
aspect of the thigh to be inserted into the upper inner part 
of the tibia, below the inner tuberosity, sending a slip to the 
fascia of the leg, i. e., it is an element of the "goose foot" in- 
sertion. 
Action-It flexes the leg on the thigh and aids in adducting 
the thigh. 
The tensor vaginae femoris is supplied by the superior gluteal 
nerve; the sartorius by the middle cutaneous; the gracilis by the 
obturator. 
Anterior Femoral Region. 
Psoas Magnus. 
Vastus Externus. 
Psoas Minor. 
Vastus Internus. 
Iliacus. 
Rectus Femoris. 
The muscles in this region are usually described as five, but 
can very readily be considered as two, viz.: biceps flexor 
femoris, consisting of psoas magnus and iliacus and the triceps 
extensor cruris, consisting of rectus femoris, vastus internus, 
and vastus externus. The last three are inserted by a common 
tendon, called the ligamentum patellae, into the anterior tubercle 
of the tibia, their action being transmitted through the patella, 
to which they are attached. 
As might be inferred from their action, they all arise from 
some point perpendicular to their insertion. THE MUSCULAR SYSTEM. 
291 
Psoas Magnus. 
The psoas MAGNUS is a long spindle-shaped muscle lying 
beside the vertebral column and descending into the thigh. It 
arises from the sides of the bodies and bases of the transverse 
processes of the last dorsal and all the lumbar vertebrae; from 
the inter-vertebral disks between them and from the tendinous 
arches attached to the bodies of the vertebrae, extending from, 
the upper lipped edge to the similar lower edge of each vertebra, 
thus leaving between it and the central constricted portion of 
the vertebra an interval through which vessels and nerves pass. 
The muscle descends beside the vertebral column to the pelvis, 
and, as it pass beneath Poupart's ligament, is joined by the 
iliacus internus, and their blended tendon is inserted into the 
trochanter minor of the femur and the bone for an inch below. 
Psoas Minor. 
The PSOAS MINOR (when present) arises from the bodies of 
the last dorsal and first lumbar vertebrae, and the disc between 
them, and is inserted by a slender tendon into the ilio-pectineal 
eminence. 
Iliacus. 
The ILIACUS arises from the whole of the iliac fossa, from the 
internal lip of the anterior three-fourths of the crest of the 
ilium, from the base of the sacrum, from the ilio-lumbar liga- 
ment, and by a few fibres from the capsular ligament of the 
hip-joint. 
The fibres converge to a tendon, which, passing beneath Pou- 
part's ligament, blends with that of the psoas magnus to be in- 
serted into the lesser trochanter of the femur and the bone for 
an inch below. 
Action-Primarily these muscles are flexors of the thigh on 
the pelvis. Owing to the winding of the tendon around the 
femur, they are powerful outward rotators, acting just as the 
biceps does on the radius. With their fixed point below, and 
the muscles of both sides acting, they bend the body directly 292 
DESCRIPTIVE ANATOMY. 
forward; but if the iliacus of one side acts alone, it flexes the 
pelvis and turns the body to the opposite side. 
The psoas is supplied by branches of the lumbar plexus, the 
iliacus by the anterior crural. 
Rectus Femoris. 
The RECTUS FEMORIS derives its name from the straightness 
of its course. It arises by a forked tendon, one fork springing 
from the anterior inferior spinous process of the ilium, the 
other from the upper margin of the acetabulum. The two soon 
unite, and the tendon thus formed after a short course ter- 
minates in the belly of the muscle; and that in turn terminates 
at the lower part of the thigh in a strong tendon, which is in- 
serted into the upper end of the patella. The fibres of this 
muscle have a bipenniform arrangement. 
Vastus Externus. 
The vastus externus arises from the base of the trochanter 
major, from the line leading from the trochanter major to the 
linea aspera, from the upper half or third of the outer lip of the 
linea aspera, and from the external inter-muscular septum. 
This muscle is covered over externally by a powerful aponeu- 
rosis from which its fibres arise. At its origin from the linea 
aspera, and the external inter-muscular septum, it is intimately 
blended with the vastus internus. Its fibres proceed in a general 
direction downward and inward, though the inferior fibres pass 
more nearly inward. It is inserted into the outer edge of the 
tendon of the rectus femoris and outer edge of the patella. 
Vastus Internus. 
The VASTUS INTERNUS arises from the whole of the shaft of 
the femur from the anterior inter-trochanteric line downward 
to within three inches of the lower end of the bone, from the 
inner lip of the linea aspera, from the internal inter-muscular 
septum, from the external inter-muscular septum, and from THE MUSCULAR SYSTEM. 
293 
a part of the external lip of the linea aspera, where it blends 
with the vastus externus. It is inserted into the inner edge 
of the tendon of the rectus femoris and inner edge of the patella. 
The origin of the muscle is also thus stated: from the inner 
surface of the shaft of the femur, from the anterior trochanteric 
line downward, from the front and outer faces, from the internal 
and external lips of the linea aspera and the internal and ex- 
ternal septa. 
The insertion of the three muscles should be thus stated: 
They combine to form a common tendon, the tendon of the 
triceps extensor cruris, which enclose the patella as a sesamoid 
bone, and is inserted, as the ligamentum patellae, into the lower 
part of the anterior tubercle of the tibia, a bursa being inter- 
posed between the tendon and the upper part of the tubercle 
of the tibia. 
The vasti muscles envelop the entire femur except the middle 
lip of the linea aspera and the two extremities of the bone. 
Action-This muscle, as its name indicates, is an extensor 
of the leg upon the thigh. The central portion, or rectus femoris, 
is also a flexor of the thigh upon the pelvis; or, acting from 
below, of the pelvis upon the thigh. 
Internal Femoral Region. 
Pectineus. 
Adductor Brevis. 
Adductor Longus. 
Adductor Magnus. 
The muscles of this region are adductors of the thigh; that is, 
they carry the thigh towards or across its fellow, and con- 
sequently they must all arise near the middle line of the body. 
Pectineus. 
The pectineus is a flat, thin muscle which arises from the 
pectineal line and triangle of the pubis and the outer face of 
Gimbernat's ligament. It passes downward and outward and 
is inserted into the upper part of the line leading from the 
trochanter minor to the linea aspera. 294 
DESCRIPTIVE ANATOMY. 
It would not be improper to describe the remaining muscles 
of this group as a single muscle with a common insertion, since, 
at the insertion, their fibres are so intimately blended as to be 
inseparable without the destruction of fibres. They are ar- 
ranged in three layers, the adductor longus, which lies on the 
same plane as the pectineous, in front, next to the adductor 
brevis, and last the adductor magnus. 
Adductor Longus. 
The adductor LONGUS arises by a small, round tendon from 
the front of the pubis just below the angle and close to the 
symphysis. It passes downward and outward, widening as it 
descends, the tendon terminating in muscular fibres, which, 
becoming tendinous in turn, are inserted into the middle third 
of the linea aspera, the fibres blending with those of the other 
adductors. 
Adductor Brevis. 
The adductor brevis arises from the front of the body and 
ramus of the os pubis, between the gracilis and obturator ex- 
ternus. It passes downward, upward and backward, rapidly 
becoming wider as it descends, and is inserted into the whole 
length of the line leading from the trochanter minor to the linea 
aspera, its insertion extending further down than that of the 
pectineus, and blending with the general adductor tendon. 
Adductor Magnus. 
The adductor MAGNUS arises from the outer side of the tuber 
ischii and from the ischio-pubic ramus. It passes downward 
and outward in large distinct bundles of fibres, and is inserted 
into the whole length of the linea aspera and by a rounded 
tendon into the adductor tubercle on the internal condyle of 
the femur. This muscle is pierced by five apertures, one above 
the other, which transmit branches of the femoral artery. The 
lowest is much the largest, and transmits the termination of THE MUSCULAR SYSTEM. 
295 
the femoral artery itself, over which the adductor longus and 
magnus throw a tendinous arch to the vastus internus, forming 
what is called Hunter's canal. 
Action-These muscles are all adductors, or muscles which 
bring the thighs together; but in addition, as their origin is 
in front of their point of insertion, the upper two are flexors. 
When the thigh has been rotated inward, they become powerful 
outward rotators. The adductors are supplied chiefly by the 
obturator nerve; the pectineus, usually, by the anterior crural. 
Scarpa's Triangle. 
On the upper front part of the thigh there is an important 
triangle, known as Scarpa's. Its outer boundary is the Sar- 
torius, its inner the adductor longus, its base is Poupart's liga- 
ment, its apex the intersection of the sartorius and the ad- 
ductor longus. Entering this triangle at the middle of its base 
and passing through it to disappear at its apex are the femoral 
artery and femoral vein. The floor of this space is formed by 
the biceps flexor femoris, pectineus, and adductor brevis. 
The Muscles and Fascias of the Leg. 
The muscles of the leg are divided into three regions, viz.: 
1, anterior tibial; 2, posterior tibial; 3, external fibular. 
These muscles are enveloped by a dense fibrous membrane 
which is found encircling the leg everywhere except on the 
front. Above it is attached to the head of the tibia and fibula 
on the sides, and is continuous with fascia lata-forming with 
it the popliteal fascia, behind. Below, it becomes attached to 
the bony prominences of the foot, forming the anterior and 
two lateral annular ligaments. From its deep face it sends off 
three broad inter-muscular septa, besides smaller ones between 
individual muscles. Two septa are found on the outer side, 
one between the peroneal and anterior groups and one between 
the peroneal and posterior groups. The third is a broad trans- 
verse septum passing between the superficial and deep muscles 
on the back of the leg. 296 
DESCRIPTIVE ANATOMY. 
Posterior Tibial Region. 
The muscles in the posterior region are placed in two layers, 
superficial and deep. 
Superficial Layer. 
Gastrocnemius 
Plantaris 
Soleus 
Gastrocnemius. 
The gastrocnemius is the large muscle which gives shape 
to the calf of the leg. It arises by two heads from the upper 
back part of the condyles of the femur and from the ridges 
which connect the condyles with the linea aspera. The two 
heads, as they descend, converge to form the lower lateral boun- 
daries of the popliteal space, and unite to form the belly of the 
muscle along which, posteriorly, a groove is continued for some 
distance. The belly terminates just below the middle of the 
leg in a large tendon called the tendo Achilles, which is inserted 
into the lower back part of the posterior tuberosity of the os 
calcis, a bursa being interposed between the tendon and the 
upper smooth part of the bone. It is the largest tendon in the 
body. 
Action-It raises the heel, and continuing to act, flexes the 
leg. 
Soleus. 
The SOLEUS is a large fleshy muscle lying beneath the gastroc- 
nemius. It has five points of origin, viz.: the head and upper 
half of the posterior aspect of the fibula, the popliteal line and 
middle third of the internal border of the tibia and from a 
tendinous arch stretched between its bony origins. The muscle 
descends to terminate about the middle of the leg in the tendon 
Achilles. 
Action-Same as the gastrocnemius, except it cannot flex 
the leg. THE MUSCULAR SYSTEM. 
297 
Plantaris. 
The plantaris is an insignificant muscle lying between the 
gastrocnemius and soleus. It arises from the back part of the 
external condyle of the femur in common with the external head 
of the gastrocnemius, the belly of the muscle passing downward 
and inward between the gastrocnemius and soleus to terminate 
in a tendon which, escaping to the inner side of the two muscles, 
passes down either to be inserted into the posterior tuberosity 
of the os calcis or to be lost in the side of the tendon Achilles. 
Action-Same as gastrocnemius. 
The three muscles just described form the triceps surge. They 
are supplied by the internal popliteal nerve. 
Deep Layer. 
Popliteus. 
Flexor Longus Digitorum. 
Tibialis Posticus. 
Flexor Longus Hallucis. 
Popliteus. 
The popliteus is a small triangular muscle resembling the 
anconeus in the upper extremity. It arises by its tendinous 
apex from a groove on the external condyle of the femur and 
passes downward and inward, adhering to the head of the 
fibula, the posterior ligament of the knee-joint and the under 
surface of the fascia which covers it, and is inserted into the 
posterior face of the tibia, and as low down as the oblique or 
popliteal line. 
Action-It flexes and inverts the leg. It is supplied by the 
internal popliteal nerve. 
Flexor Longus Hallucis. 
The flexor longus hallucis arises from the lower two-thirds 
of the fibula, except the last inch, and from the inter-muscular 
septa. It descends behind the internal malleolus into the sole 
of the foot, crosses the tendon of the flexor longus digitorum 298 
DESCRIPTIVE ANATOMY. 
and is inserted into the base of the last phalanx of the great toe. 
Action-It flexes the last phalanx of the great toe and, con- 
tinuing to act, extends the foot. 
Flexor Longus Digitorum. 
The flexor LONGUS digitorum arises from the lower two- 
thirds of the tibia, except the last two or three inches, and 
from the inter-muscular septa. It passes downward behind the 
internal malleolus, divides into four tendons, which are crossed 
by the flexor longus pollicis, and are inserted into the bases of 
the last phalanges of the four outer toes. 
Its action is indicated by its name, after flexing the toes it 
extends the foot on the leg. 
Tibialis Posticus. 
The tibialis POSTICUS arises from the whole length of the 
posterior surface of the interosseous membrane, from the adja- 
cent edges of the tibia and fibula and from the inter-muscular 
septa. It descends behind the internal malleolus, after crossing 
the flexor longus digitorium, and is inserted into the tuberosity 
of the scaphoid bone and into the internal cuneiform bone. 
Action-It is an extensor and adductor of the foot. 
The three last muscles all arise from the interosseous mem- 
brane; and as the flexor longus pollicis arises from the outer 
bone of the leg and is inserted into the inner toe, it must cross 
the flexor longus digitorum. This crossing takes place in the 
sole of the foot and is known as the decussation of the tendons, 
which are connected at this point by a small slip. The flexor 
longus pollicis lies above the flexor longus digitorium in the 
sole of the foot. 
The popliteus is supplied by the internal popliteal nerve. The 
other muscles are supplied by the posterior tibial nerve. THE MUSCULAR SYSTEM. 
299 
The Interosseous Membrane. 
The interosseous membrane is a strong ligamentous mem- 
brane which passes from tibia to fibula and is attached to their 
adjacent edges, after the manner of the interosseous mem- 
brane of the forearm. On its posterior aspect it is entirely 
appropriated by the tibial muscles. The muscles in the deep 
layer are separated from those in the superficial layer by a 
strong thick fascia. 
Anterior Region of the Leg. 
Tibialis Anticus. 
Extensor Proprius Pollicis. 
Extensor Longus Digitorium. 
Of the three muscles in this group two have four points of 
origin in common. These four points are as follows: 1, outer 
tuberosity of the tibia; 2, investing fascia of the leg; 3, inter- 
muscular septum; 4, interosseous membrane. 
Tibialis Anticus. 
The tibialis anticus arises from the common origin (the 
outer tuberosity of the tibia, the investing fascia, the inter- 
muscular septum between itself and the extensor longus digi- 
torum and the interosseous membrane) and from the upper 
two-thirds of the outer face of the tibia. It passes downward 
to terminate in a tendon which runs beneath the anterior annular 
ligament and is inserted into the inner and under surface of the 
internal cuneiform bone and into the base of the metatarsal bone 
of the great toe. 
Action-It flexes the foot; and, according as it acts with the 
tibialis posticus or the peronei, it inverts or everts the foot. 
Extensor Longus Digitorum. 
The extensor LONGUS digitorum arises from the common 
origin (outer tuberosity, investing fascia, inter-muscular sep- 300 
DESCRIPTIVE ANATOMY. 
turn between itself and the tibialis anticus internally and the 
peroneus longus externally, and the interosseous membrane) 
and from the head and whole length of the anterior aspect of 
the shaft of the fibula, except the last inch. It descends and 
divides into five tendons, which pass beneath the anterior an- 
nular ligament and are inserted as follows: one into the base 
of the metatarsal bone of the little toe, the other four into the 
backs of the four lesser toes after the manner of extensor ten- 
dons. That part of the muscle inserted into the base of the 
metatarsal bone of the little toe, and arising from the lower 
fourth of the fibula, is sometimes called the peroneus tertius. 
Action-It extends the toes; and, by its insertion into the 
metatarsal bone of the little toe, flexes the foot. 
Extensor Proprius Pollicis. 
The extensor proprius pollicis is shorter than the two pre- 
ceding muscles and lies between and is overlapped by them. 
It arises from the middle two-fourths of the shaft of the fibula 
and from the interosseous membrane, and terminates in a ten- 
don which passes beneath the anterior annular ligament and is 
inserted into the base of the last phalanx of the great toe. Its 
action is indicated by its name. 
The anterior annular ligament is a strong oblique ligamentous 
band which binds the tendons of the three preceding muscles 
down on the front ankle. It consists of an upper part passing 
from the tibia to the fibula and containing the compartment for 
the tibialis anticus; and a lower portion, attached above to the 
inner malleolus and below to the lesser process of the os calcis 
which forms the swing ligament containing the sheath for the 
extensor longus digitorum and the extensor proprius pollicis. 
A small offshoot of this band passes to the plantar fascia. 
These muscles are supplied by the anterior tibial nerve. 
External Region of the Leg. 
Peroneus Longus. 
Peroneus Brevis. THE MUSCULAR SYSTEM. 
301 
Peroneus Longus. 
The peroneus, or fibularis, longus arises from the head and 
upper two-thirds of the outer aspect of the shaft of the fibula, 
from the investing fascia and the inter-muscular septa between 
itself and the extensor longus digitorum on the inner and the 
posterior group on the outer side; below another septum is 
found between the two peroneal muscles. It descends to ter- 
minate in a tendon which passes behind the external malleolus, 
through the lower groove on the outer surface of the os calcis, 
reaches the sole of the foot and is directed across it obliquely 
forward and inward, through a groove in the cuboid bone, to 
be inserted into the base of the metatarsal bone of the great toe. 
Action-It is an extensor and everter of the foot. 
Peroneus Brevis. 
The peroneus, or fibularis, brevis derives its name from its 
position and because its origin and insertion are both short of 
the preceding muscle, beneath which it lies. It arises from the 
lower two-thirds of the outer aspect of the shaft of the fibula 
and from the inter-muscular septum, descends behind the exter- 
nal malleolus, through the upper groove on the outer surface of 
the os calcis, and is inserted into the base of the metatarsal 
bone of the little toe. 
Action-It extends and everts the foot. 
The two peronei muscles, as they are passing the outer mal- 
leolus, are held down by the external annular ligament. 
They are supplied by the musculo-cutaneous nerve. 
Muscles of the Foot. 
The foot is divided into two regions, dorsal and plantar. 
The fascia covering the dorsum of the foot is thin and mem- 
branous. Above it is continuous with the anterior annular liga- 
ment, while on the sides it becomes attached to the plantar 
fascia. On either side there is a strong lateral annular ligament 
each continuous above with the fascia of the leg and below with 302 
DESCRIPTIVE ANATOMY. 
the plantar fascia. The internal annular ligament is attached 
to the internal malleolus above and to the inner face of the os 
calcis below. It forms canals for the passage of the flexor ten- 
dons. 
The external annular ligament is attached to the external mal- 
leolus and to the outer margin of the os calcis forming canals 
for the peroneal tendons. 
Dorsum of the Foot. 
Extensor Brevis Digitorum. 
The extensor brevis digitorum arises from the upper and 
outer aspect of the os calcis and passing forward and inward 
divides into four tendons, the innermost of which is inserted 
into the base of the first phalanx of the great toe, the other 
three into the backs of the next three toes in common with the 
long extensor tendons. 
Its name indicates its action. 
The Sole of the Foot. 
The Plantar Fascia. 
When the thick skin on the sole of the foot has been removed, 
there is brought into view a thick mass of fatty tissue, and be- 
neath this is a strong fascia called plantar fascia. It consists of 
a strong, thick central portion, and, on either side, continuous 
with this, a thinner lateral portion. The central portion begins 
behind at the under surface of the os calcis, runs forward and 
just beyond the middle of the sole divides into five branches, 
each of which passes forward to the base of a corresponding 
toe. The muscles of the sole all lie beneath (or, in the erect 
position, above) this fascia and are divided into groups in ac- 
cordance with the subdivisions of the plantar fascia, viz.: a cen- 
tral and two lateral groups. The propriety of this division is 
shown by the fact that the plantar fascia sends up to the bone 
intermuscular or dividing septa from the line of union of the 
central and two lateral portions. THE MUSCULAR SYSTEM. 
303 
In describing these muscles, however, they are taken in lay- 
ers, of which there are three. When the plantar fascia, the dis- 
section of which is the first step, has been removed, the first 
layer, consisting of one muscle in each group, is exposed. This 
constitutes the second view in the dissection of the sole. 
First Layer. 
Abductor Pollicis. 
Flexor Brevis Digitorum. 
Abductor Minimi Digiti. 
The three muscles forming the first layer have a common 
origin, viz.: 1, the under surface of the os calcis; 2, the plantar 
fascia which covers them; 3, the intermuscular septa which sepa- 
rate them. Some of the plantar fascia should be left on the 
muscles in dissecting them, since it is a part of their origin. 
Abductor Pollicis. 
The abductor pollicis is the innermost of the three muscles 
of the first layer. It arises from the common origin, and is in- 
serted into the inner side of the base of the first phalanx of the 
great toe. 
Its name indicates its action. 
Abductor Minimi Digiti. 
The abductor minimi digiti is the outer of the three muscles 
in the first layer. It arises from the common origin, and is in- 
serted into the outer side of the base of the first phalanx of the 
little toe. 
Its name indicates its action. 
Flexor Brevis Digitorum. 
The FLEXOR BREVIS digitorum lies in the centre of the first 
layer. It arises from the common origin, passes forward, and 
divides into four tendons for the four lesser toes. Each tendon 304 
DESCRIPTIVE ANATOMY. 
splits to allow the passage of the tendon of the long flexor, and 
is inserted into the sides of the shaft of the second phalanx. 
Its name indicates its action. 
Second Layer. 
Musculus Accessorius 
Lumbricales 
The second layer, exposed by removing the first, is the third 
view in the dissection of the sole. It consists of the musculus 
accessorius, the lumbricales and the tendons of the flexor longus 
pollicis and flexor longus digitorum. These two tendons, soon 
after entering the sole from behind the internal malleolus, cross 
each other, forming their decussation, and are also connected 
by slips so that one muscle cannot act independently of the 
other, but throws the part to which it is attached into slight 
motion. 
Musculus Accessorius. 
The MUSCULUS accessorius arises tendinous and fleshy from 
the under surface of the os calcis and passing forward is in- 
serted into the outer side and upper surface of the tendon of the 
flexor longus digitorum just as it splits into its four branches. 
Action-It corrects the obliquity which would otherwise be 
imparted to the four lesser toes by the action of the long flexor. 
Lumbricales. 
The lumbricales are four little worm-like muscles, three of 
which arise from the bifurcation of the tendon of the flexor 
longus digitorum, while the fourth springs from the inner side 
of the inner tendon of that muscle. They pass between the toes 
and are inserted into the tibial side of the extensor tendons of 
the four lesser toes. 
Action-They aid the flexor longus digitorum. THE MUSCULAR SYSTEM. 
305 
Third Layer. 
Flexor Brevis Pollicis 
Flexor Brevis Minimi Digiti 
Adductor Obliquus Pollicis 
Transversus Pedis 
This layer, constituting the fourth view in the dissection of 
the sole of the foot, is exposed by removing the second layer. 
Flexor Brevis Pollicis. 
The flexor brevis pollicis arises from the cuboid bone, the 
external cuneiform bone and the expanded tendon of the tibialis 
posticus. It is inserted into both sides of the base of the first 
phalanx of the great toe, each tendon having a sesamoid bone 
in it. 
Adductor Obliquus Pollicis. 
The ADDUCTOR OBLIQUUS pollicis arises from the cuboid bone, 
from the sheath of the tendon of the peroneous longus, and from 
the bases of the adjoining metatarsal bones (second, third, and 
fourth). It is inserted into the outer side of the base of the 
first phalanx of the great toe. 
Flexor Brevis Minimi Digiti. 
The FLEXOR BREVIS minimi digiti arises from the base of the 
fifth metatarsal bone, and is inserted into the outer side of the 
first phalanx of the little toe. 
Transversus Pedis. 
The TRANSVERSUS pedis (adductor transversus hallucis) arises 
by slips from the heads of the three outer metatarsal bones, and 
passing inward is inserted into the outer side of the base of the 
first phalanx of the great toe. 
Action-It is an adductor of the great toe. DESCRIPTIVE ANATOMY. 
306 
Interosseous Muscles. 
Lying between the metatarsal bones are certain small muscles, 
called from their position interosseous. There are seven of 
these muscles, four dorsal and three plantar. They are bipenni- 
form muscles, arising from the metatarsal bones and inserted 
into the first phalanges. Of the four dorsal the first and second 
are inserted into the inner and outer sides, respectively, of the 
second toe and into the tendon of the common extensor. The 
third and fourth are inserted into the outer sides of the third 
and fourth toes and their extensor tendons. The plantar interos- 
sei, three in number, arise from the inner and under sides of 
the metatarsal bones of the third, fourth and fifth toes, and are 
inserted into the inner sides of the bones of the first phalanges 
of the same toes and into the extensor tendons. 
Nerves. The internal plantar nerve supplies the abductor 
and flexor brevis pollicis, the inner half of the flexor brevis digi- 
torum and the inner two lumbricales. All the other muscles of 
the sole are supplied by the external plantar. The extensor 
brevis is supplied by the anterior tibial. 
The Muscles of the Face. 
The muscles of the face are arranged in groups, viz: those 
connected with the orbit, with the nose, the mouth and a very 
unimportant group connected with the auricle. 
Orbital Group-Three Muscles. 
Orbicularis Palpebrarum. 
The orbicularis palpebrarum is an elliptical musc1e. lying 
just beneath the skin, in front of the orbit, the portion which 
lies on the lid being thinner and paler than the rest. It arises 
from the tendo oculi and adjacent bone; and the fibres, form- 
ing an ellipse around the orbit, return to the place from which 
they started. The tendo oculi is a fibrous cord, which is at- 
tached by one end to the orbital aspect of the nasal process of THE MUSCULAR SYSTEM. 
307 
the superior maxilla, while the other end bifurcates to be at- 
tached to the inner extremities of the tarsal cartilages. 
Externally the orbicularis palpebrarum is attached to the tem- 
poral fascia. 
Action-It closes the eyelids. It is one of the sphincter mus- 
cles, but in its action differs from most of them in being im- 
movably attached at its extremities. When its fibres contract 
they bring the eyelids together in a line corresponding to its 
points of attachment, whereas most sphincter muscles close the 
aperture which they surround by an approximation of all their 
fibres at the same time, and in the same proportion, towards 
the centre of the aperture, e. g., the orbicularis oris, in the act 
of whistling, since it has no bony attachment. 
Corrugator Supercilii. 
The corrugator supercilii is a small muscle which arises 
from the inner extremity of the superciliary ridge, on each 
side, passes outward and is lost in the deep face of the orbicu- 
laris palpebrarum. 
Action-It throws the skin of the forehead into vertical folds, 
i. e., corrugates the brow. 
Tensor Tarsi. 
The TENSOR TARSI, or Horner's muscle, is very small. It 
arises from the orbital surface of the lachrymal bone, passes 
outward and divides into two slips which are inserted into the 
tarsal plates. 
Cranial Group. 
Occipito-Frontalis. 
The OCCIPITO-FRONTALIS of either side arises from the superior 
curved line of the occipital bone and the mastoid process. It is 
tendinous at its origin, but becomes fleshy as it passes forward; 
and then, as it is mounting over the vault of the cranium, it 
forms a broad aponeurosis and, descending on the forehead again 308 
DESCRIPTIVE ANATOMY. 
becomes fleshy to be lost in the orbicularis palpebrarum and 
corrugator supercilii, its innermost fibres forming the pyra- 
midalis nasi muscle. 
Action-It raises the brows and throws the skin of the fore- 
head into wrinkles, and can move the scalp backward or for- 
ward. 
Nasal Group-Three Muscles. 
Pyramidalis Nasi. 
The pyramidalis NASI is formed by the innermost fibres of 
the occipito-frontalis, which descending, are lost on the bridge 
of the nose. 
Action-It draws down the inner extremity of the eyebrow 
and elevates the nose. 
Compressor Naris. 
The COMPRESSOR naris, triangular in shape, arises from the 
canine fossa on the superior maxilla by its apex and, mounting 
on the side of the nose, meets its fellow of the opposite side in 
a tendinous raphe on the bridge of the nose. 
Action-The two compress the nostrils. 
Depressor Alae Nasi. 
The depressor alae nasi is found just beneath the mucous 
membrane of the upper lip. It arises from the incisive fossa 
of the superior maxilla and is inserted into the ala of the nose. 
Its name indicates its action. 
The muscles of the face are nearly all small and pale and 
fatty. As a rule they arise from the bone and are inserted into 
soft parts. Their action produces the varying expression of 
which the face is capable. 
Muscles of the Mouth. 
The muscles of the mouth consist of two groups, superior 
and inferior labial groups, and one muscle, the orbicularis oris, 
which belongs to both groups. THE MUSCULAR SYSTEM. 
309 
Orbicularis Oris. 
The orbicularis oris is the sphincter muscle of the mouth; 
as it has but slight connection with bone, this attachment may 
be disregarded. It consists of two segments, one in each lip, 
which meet at the angles of the mouth. 
Action-It can close the mouth in two ways, either by bring- 
ing the lips together in a horizontal line or by approximating 
the angles of the mouth at the same time. 
Superior Labial Group. 
Levator Labii Superioris Alaeque Nasi. 
The LEVATOR LABH superioris alaeque nasi arises from the 
nasal process of the superior maxilla and, descending, divides 
into two slips, one of which is inserted into the ala of the nose 
while the other continues on to be inserted in the upper lip. 
Its name indicates its action. 
Levator Labii Superioris Propius. 
This muscle arises from the orbital ridge of the superior 
maxilla and descends to be inserted into the upper lip. 
Its name indicates its action. 
Levator Anguli Oris. 
The levator ANGULI oris, or canine muscle, arises from the 
canine fossa of the superior maxilla and passes downward and 
outward to be inserted into the angle of the mouth. 
Its name indicates its action. 
The Zygomatic Muscles-Two. 
The ZYGOMATIC are two small muscles which arise from the 
zygomatic process of the malar bone and pass downward and 
inward. The zygomaticus major, the lower one, is inserted into 310 
DESCRIPTIVE ANATOMY. 
the angle of the mouth and the zygomaticus minor into the 
upper lip. 
Action-They carry the angle of the mouth upward and out- 
ward. 
Inferior Labial Group. 
Quadratus Menti. 
The quadratus menti, or depressor labii inferioris, is a 
square-shaped thin muscle which arises from the oblique line 
on the front of the lower jaw near the symphysis and, passing 
upward, is lost in the lower lip. 
Its synonym indicates its action. 
Triangularis. 
The triangularis, or depressor anguli oris, arises by its base 
just external to the preceding and is inserted by its apex into 
the angle of the mouth. 
Its synonym indicates its action. 
Levator Labii Inferioris. 
The LEVATOR labii inferioris lies just beneath the mucous 
membrane. It arises from the incisive fossa of the inferior 
maxilla and is inserted into the integument of the chin. 
Its action is indicated by its name. 
The Ocular Group. 
External Rectus 
Levator Palpebrae Superioris 
Inferior Rectus 
Superior Rectus 
Internal Rectus 
Superior Oblique 
Inferior Oblique. 
The muscles forming this group are found within the orbit. 
All of them, except the levator palpebrse superioris, are attached 
to the eye-ball, and all, except the inferior oblique muscle, arise THE MUSCULAR SYSTEM. 
311 
at the apex of the orbit and pass forward flat, straight and 
widening as they advance toward their insertion. 
Four of them, from the direction of their fibres, are called 
recti, and are concerned in moving the eye-ball. They are dis- 
tinguished as: 1, superior rectus, because it lies above the eye- 
ball and draws the front of the eye upward; 2, inferior rectus, 
because it lies below the eye-ball, and draws its front down- 
ward; 3, external rectus, because it lies external to the eye- 
ball and draws its front outward; 4, internal rectus, because it 
lies internal to the eye-ball and draws its front inward. By a 
combined action of these muscles the front of the eye can be 
moved in all directions intermediate between those mentioned. 
All the recti arise from the apex of the orbit, that is, the margin 
of the optic foramen, and also receive an origin from the fibrous 
sheath of the optic nerve. They run forward and are inserted 
into the sclerotic coat about one-fourth of an inch behind the 
circumference of the cornea. Some give as the origin of three 
of these muscles the ligament of Zinn, which is a fibrous band 
attached around the lower portion of the circumference of the 
optic foramen. This, however, is an unnecessary refinement. 
These muscles differ but slightly in size and length. 
Levator Palpebrae Superioris. 
Lying just beneath the root of the orbit, and between it and 
the superior rectus, is a muscle closely resembling the recti called 
levator palpebral superioris since its action is to raise the 
upper lid. It arises from the upper margin of the optic fora- 
men and sheath of the optic nerve, passes forward and is in- 
serted into the upper edge of the superior tarsal cartilage. 
Inferior Rectus. 
The inferior rectus arises from the lower margin of the 
optic foramen and from the sheath of the optic nerve. It passes 
forward and is inserted into the under surface of the sclerotic 
about one-fourth of an inch behind the cornea. 312 
DESCRIPTIVE ANATOMY. 
External Rectus. 
The external RECTUS arises by a forked origin from the outer 
margin of the optic foramen and from the sheath of the optic 
nerve. It passes forward and is inserted into the outer surface 
of the sclerotic coat about one-fourth of an inch behind the cir- 
cumference of the cornea. It is important to remember its 
forked origin, since many nerves pass through the interval be- 
tween its heads. 
Internal Rectus. 
The internal rectus arises from the inner margin of the 
optic foramen and sheath of the optic nerve. It passes forward 
and is inserted into the inner surface of the sclerotic coat about 
one-fourth of an inch behind the circumference of the cornea. 
Superior Rectus. 
The superior rectus arises from the upper margin of the 
optic foramen and from the fibrous sheath of the optic nerve. 
It passes forward and is inserted in the sclerotic coat one-fourth 
of an inch behind the cornea. It is the thinnest of the recti. 
Inferior Oblique. 
The inferior oblique is a narrow and thin muscle, arising 
from the orbital surface of the superior maxilla, near the inner 
side of the orbit. It passes out beneath the eye-ball and in- 
ferior rectus to be inserted into the sclerotic near, but behind, 
the insertion of the optic nerve, on the under aspect of the eye- 
ball. 
Superior Oblique or Trochlearis. 
The superior oblique arises from the 'inner margin of the 
optic foramen and sheath of the optic nerve. It passes forward 
along the upper inner wall of the orbit to its front, where, be- 
coming tendinous, it plays through a cartilaginous ring fixed 
to the fovea trochlearis: thence its tendon passes outward and THE MUSCULAR SYSTEM. 
313 
backward, beneath the superior rectus, to be inserted into the 
outer aspect of the sclerotic about half way between the cir- 
cumference of the cornea and the entrance of the optic nerve. 
Action-Its action is computed from the pulley at the fovea 
trochlearis-hence it rotates the eye-ball on its antero-posterior 
axis and draws it forward. 
Nerves. The facial muscles are all supplied by the seventh, 
or facial, nerve. Of the orbital muscles five (all except the 
superior oblique and external rectus) are supplied by the third 
nerve. The superior oblique is supplied by the fourth and 
the external rectus by the sixth. 
Muscles of Mastication. 
Masseter 
External Pterygoid 
Temporal 
Internal Pterygoid. 
Buccinator. 
Masseter. 
The masseter arises from the anterior two-thirds of the 
zygomatic arch by a bundle of fibres which pass downward and 
backward to be inserted into the angle and posterior part of 
the outer surface of the lower jaw; beneath these fibres is a 
smaller bundle arising from the posterior third of the zygomatic 
arch and passing downward and forward to be inserted into 
the outer face of the ramus nearly to the basilar border of the 
bone. 
Action-The two muscles, acting together, draw the lower 
jaw powerfully upward and press the teeth firmly against the 
teeth of the upper. The superficial fibres draw the jaw forward 
while the deep fibres carry it backward. 
The masseter is covered by a strong fascia, derived from the 
cervical fascia, which is attached below to the lower jaw, and 
blends with the deep cervical fascia, while above it is attached 
to the zygoma and forms the parotid fascia. 314 
DESCRIPTIVE ANATOMY. 
Buccinator. 
The buccinator, or trumpeter's muscle, is the bulkiest ele- 
ment of the cheek. It arises from the alveolar process of the 
superior maxilla, from the external oblique ridge of the lower 
jaw, as far forward as the second bicuspid tooth and from 
the pterygo-maxillary ligament. Its fibres converge to be in- 
serted into the angle of the mouth. 
Action-The buccinators compress the cheeks, keeping food 
between the teeth or expelling air through the lips. 
The pterygo-maxillary ligament extends from the hamular 
process of the pterygoid plate to the posterior extremity of the 
molar ridge of the lower jaw. In front it gives origin to some 
of the fibres of the buccinator and behind to the superior con- 
strictor of the pharynx. 
Temporal. 
This muscle is found in a fossa, and is covered by a fascia, 
bearing the same name. The temporal fascia is a dense, shin- 
ing aponeurosis which is attached above to the temporal ridge 
on the side of the skull; while below it divides into two layers, 
one seizing the outer and one the inner edge of the upper border 
of the zygomatic arch. The deep surface of the fascia gives 
origin to part of the temporal muscle. 
The temporal is a radiated muscle occupying the temporal 
fossa. It arises from the whole of the temporal fossa, from 
the whole length of the temporal ridge and from the temporal 
fascia which covers it. It passes downward, its fibres converg- 
ing, and is inserted into the apex and inner side of the coronoid 
process of the inferior maxilla. 
Action-It is a powerful elevator of the lower jaw, acting in 
concert with the masseter. Its power is greatest when the jaw 
is depressed, while the power of the masseter increases as the 
jaws are approximated. THE VASCULAR SYSTEM. 
315 
External Pterygoid. 
The external pterygoid arises by two heads, one from the 
lower surface of the greater wing of the sphenoid, from the 
pterygoid ridge and sphenoidal spine, and the other from the 
whole of the outer face of the external pterygoid plate. The 
fibres pass backward and outward and narrow to a tendon 
which is inserted into the neck of the condyle of the lower jaw 
and into the inter-articular fibro-cartilage. 
Action-The two muscles acting together, will carry the lower 
jaw directly forward. One muscle alone draws the jaw for- 
ward and to the opposite side. It is the alternate action of the 
two muscles which produces the grinding motion necessary for 
bruising the food. 
Internal Pterygoid. 
The INTERNAL pterygoid, or internal masseter arises from 
the inner face of the outer pterygoid plate, from the grooved 
posterior face of the tuberosity of the palate and occasionally 
by a slip from the tuberosity of the superior maxilla. It passes 
downward, outward and is inserted into the inner face of the 
angle and ramus of the lower jaw. 
Action-It acts almost exactly like the superficial fibres of 
the masseter, drawing the jaw forward and upward. Its origin 
being nearer the middle line, however, it also draws the jaw 
inward, thus aiding the external pterygoid in grinding the food. 
Arteries and nerves. All the muscles of mastication are sup- 
plied by the muscular branches of the inferior maxillary divi- 
sion of the fifth, except the buccinator, which also receives a 
branch from the facial. The internal maxillary artery fur- 
nishes blood. 
THE VASCULAR SYSTEM. 
The Arteries. 
There are two sets of arteries: one the Pulmonary System, 
the other the Systemic System. The two systems communicate 
with one another. 316 
DESCRIPTIVE ANATOMY. 
In the Systemic circulation the blood starts from the heart 
in the large arteries, and passes on into the branches which 
spring from those arteries, these branches diminishing in size 
until the capillaries are reached. Returning, the blood passes 
through the veins, which increase in size as we approach the 
heart. 
The Pulmonary circulation. The heart is divided into four 
chambers: two left, one above and one below; and two right, 
one above and one below. From the lower chamber on the left 
the systemic circulation starts. Entering into the upper cham- 
ber on the right is the termination of the venous system; and 
from this chamber the blood is poured into the chamber below 
by means of two inlets. From there it passes into a cavity 
from which the pulmonary artery starts, this artery breaking 
up into two branches and passing to the lungs. After making 
the circuit of the lungs, the blood is returned into the upper 
left side of the heart, from which it drops down into the other 
left cavity, where the aorta starts. 
The systemic arteries all commence with the one great trunk, 
the aorta; but for several reasons we generally begin our study 
with one of the arteries belonging to the upper extremity or 
head and neck. 
Arteries decrease in size as they throw off branches; but if 
we consider the combined area of the two branches into which 
the artery is divided, we find that this area is greater than 
that of the original trunk. Similarly, if we consider the com- 
bined area of all the branches which spring from any given 
artery, we find that this area is infinitely greater than that of 
the original artery. On the other hand, the combined area of 
the veins is larger than the combined area of the great veins 
which return the blood to the heart, and is much larger than 
the combined area of the arteries. Consequently, as the blood 
continues its course in circulating through the body the rapidity 
of the current decreases in proportion as the distance from 
the heart increases. As the veins decrease in size, or containing 
capacity, as they approach the heart, the current becomes 
swifter, but never anything like as swift as the current in the 
arteries. THE VASCULAR SYSTEM. 
317 
In describing an artery we not only give the region in which 
it lies, its course and termination, but its relations, divided for 
definiteness of description into muscular, visceral and cord re- 
lations. Often these relations include a vein, or another artery; 
and there is usually something else to be noticed, for instance, 
a tendon. Besides that, arteries have other coverings, skin and 
fascia; and other relations, which are neither cords, fascias nor 
muscles. Such, for instance, are the thyroid gland, the trachea, 
the pharyx, or the thymus gland. To describe an artery we 
state how and where it begins, in what direction it runs, how 
and where it terminates. Its coverings and muscular relations 
come next; then its companion vein or veins; then other cord, 
visceral or other relations; and, lastly, the branches are de- 
scribed. An artery may begin by springing from some great 
trunk (as the innominate from the aorta), by a trunk bifurcat- 
ing into two branches (as the bifurcation of the innominate 
into the right common carotid and right subclavian) by a simple 
change of name (as the subclavian becoming the axillary), or 
by an axis breaking into a number, usually three, of branches 
(as the coeliac axis breaking into the gastric, splenic and hepa- 
tic). Sometimes an artery is divided into two or more por- 
tions, for convenience in studying its relations. In such cases 
it is more accurate to state, first, all the structures found in 
contact with the vessel, and, later, to study each portion sepa- 
rately. 
It would be natural to begin the study of the arterial system 
with the aorta, but it is more convenient to dissect the great 
vessels of the neck first, hence we commence with the right 
common carotid. 
The Right Common Carotid. 
The RIGHT COMMON carotid artery differs from the left in 
that it spring's from the arteria innominata, whereas the left 
springs directly from the arch of the aorta, hence the relations 
of the first portion of the left common carotid would be dif- 
ferent from the relations of the right common carotid in this 
portion. The relations after they have passed from the thoracic- 
cavity, and have reached the back of the sterno-clavicular articu- 318 
DESCRIPTIVE ANATOMY. 
lation, become identical; and then the description of one vessel 
will apply to the other. 
The right common carotid commences by being one of the 
two terminal branches of the arteria innominata. It then passes 
upward with a slight inclination backward and outward, lying 
upon the anterior tubercles of the transverse process of the 
four lower cervical vertebrae, to a point about on a line drawn 
from the upper border of the thyroid cartilage. After reaching 
that point it terminates by dividing into two branches, which 
are known as the internal and external carotid arteries. 
Covering the vessel we find, first, the skin; then a layer of 
superficial cervical fascia; then the platysma myoides muscle; 
then the first layer of deep cervical fascia; then the sterno- 
cleido-mastoid muscle; then the second layer of deep cervical 
fascia. Beneath this lie the sterno-hyoid and the anterior belly 
of the omo-hyoid, while on a deeper plane lies the sterno-thyroid, 
followed by the sheath of the vessel and then the vessel itself. 
Behind this is the posterior wall of the sheath and then the 
prevertebral group of muscles, separating the artery from the 
transverse processes of the cervical vertebrae. External to the 
artery, and in the same sheath, is the internal jugular vein, and 
also in the sheath, between the vein and the artery and on the 
same plane, is the pneumogastric nerve. Behind is the cervical 
portion of the sympathetic, recognized by its large ganglion, the 
recurrent laryngeal nerve, and the inferior thyroid artery. In- 
ternally are the trachea, thyroid gland, larynx, pharynx, recur- 
rent laryngeal nerve, and the inferior thyroid artery. In front 
are the anterior jugular vein, the middle and superior thyroid 
veins, the descenclens, hypoglossi and communicans nerves, and 
the sterno-mastdid artery. 
The artery is divided into two portions by the passage of the 
omo-hyoid. The first portion extends from the beginning of 
the artery to the anterior belly of the omo-hyoid; the second 
from that muscle to the termination of the artery. 
The first portion commences by being a branch of bifurcation 
of the innominate, passes upward and slightly outward to the 
anterior belly of the omo-hyoid, and terminates by becoming 
the second portion. It is covered in front by the skin, superfi- THE VASCULAR SYSTEM. 
319 
cial fascia, platysma, deep fascia, sterno-mastoid, sterno-hyoid, 
sterno-thyroid, the sheath of the vessel, and the anterior jugu- 
lar vein. The sterno-hyoid and sterno-thyroid muscles draw 
away from the artery as they ascend that neck, and have be- 
come antero-internal at the upper part of its course. The in- 
ferior thyroid artery, the cervical portion of the sympathetic, 
and recurrent laryngeal nerves are behind this portion. The 
sympathetic descends as a continuous posterior relation, the re- 
current nerve crosses to the inner side of the artery just above 
the subclavian, while the inferior thyroid rises to the level of 
the thyroid body before passing behind the artery. Internal to 
this portion are the trachea, thyroid gland, the recurrent laryn- 
geal nerve, and the inferior thyroid artery. The recurrent 
laryngeal is first behind and external, then directly behind and 
finally internal. Externally are the internal jugular vein and 
pneumogastric nerve. 
The second portion begins by being a continuation of the 
first portion at the anterior belly of the omo-hyoid muscle, and 
passes to the upper border of the thyroid cartilage, where it 
terminates by dividing into the internal and external carotid 
arteries. This portion of the artery lies in the triangle of elec- 
tion, and is covered in front by the skin, superficial fascia, pla- 
tysma, first layer of the deep fascia, and is overlapped by the 
sterno-mastoid, beneath which comes the sheath of the vessels. 
On the front of the sheath the descendens noni passes down- 
ward as a continuous relation, being joined just above the omo- 
hyoid by one or two branches from the cervical plexus, called 
the communicans noni, forming Scarpa's arch. Sometimes this 
nerve is in the sheath. At its upper part the vessel is crossed by 
the sterno-mastoid artery, and below this point by the middle 
and superior thyroid veins. Behind the sympathetic is a con- 
tinuous relation, lying between the artery and the prevertebral 
group of muscles. Externally are the internal jugular and the 
pneumogastric. Internally are the larynx and pharynx. 
At the root of the neck the common carotid arteries are 
deeply seated and placed close together. As they ascend, the 
trachea and larynx are thrust forward between them, giving 
the arteries the appearance of sinking into the neck, although 320 
DESCRIPTIVE ANATOMY. 
they become more and more superficial as they ascend. Unlike 
most arteries, the common carotid gives off no wayside branches. 
For the upper part of its course this work is performed by 
branches from the external carotid, while below the subclavian 
takes up the work. 
External Carotid. 
The external carotid artery, one of the two terminal 
branches of the common carotid, begins where that artery bifur- 
cates about on a level with the upper border of the thyroid 
cartilage, and, continuing the direction of the common carotid, 
passes beneath the posterior belly of the digastric and the stylo- 
hyoid muscles, enters the substance of the parotid gland, and 
terminates in that gland behind the neck of the condyle of the 
lower jaw by dividing into two branches, the temporal and 
the internal maxillary arteries. The temporal continues the 
course of the external carotid to mount over the zygoma and be 
distributed to the side of the head by two branches, while the 
internal maxillary passes inward, behind the neck of the con- 
dyle of the lower jaw to supply the deep structures of the face. 
This artery is divided, for convenience of description into 
three portions. 
The first portion of the external carotid lies in the superior 
carotid triangle, its length varying as the common carotid di- 
vides on a level with, above or below the upper border of the 
thyroid cartilage, for it extends from the bifurcation of the 
common carotid to the lower border of the stylo-hyoid. It is 
covered by the integument and platysma and deep cervical fas- 
cia, is slightly overlapped by the sterno-mastoid, and is crossed 
in front by the hypoglossal or twelfth nerve, near the termina- 
tion of this portion, and the lingual vein near its beginning. 
Between these it is crossed by the ranine and facial veins. At 
its commencement the internal carotid lies to its outer side; but 
by the time the external carotid reaches the termination of its 
first portion, the internal carotid has passed behind it. In- 
ternally are the superior and external laryngeal nerves, sepa- 
rating it in part from the outer wall of the pharynx, with which 
it is at first in contact. THE VASCULAR SYSTEM. 
321 
The second portion is that which is crossed by the stylo-hyoid 
and posterior belly of the digastric. Its coverings are integu- 
ment, platysma, stylo-hyoid, and posterior belly of the digastric. 
The stylo-glossus and pharyngeus muscles, glosso-pharyngeal 
and superior laryngeal nerves and stylo-hyoid ligament cross be- 
tween this and the internal carotid about on a line between the 
second and third portions. 
The third and last portion extends from the upper border of 
the posterior belly of the digastric to the termination of the 
artery behind the neck of the condyle of the lower jaw. It lies 
embedded in the substance of the parotid gland, and is crossed, 
superficially, near its termination, by the facial nerve and the 
facial and temporo-maxillary veins. The first portion is most 
superficial, the second the shortest, and the third the longest 
and deepest. 
Branches. 
Superior Thyroid 
Occipital 
Lingual 
Posterior Auricular 
Facial 
Parotidean. 
Ascending Pharyngeal 
It should be remembered that the common carotid gives off 
no branches except its terminal ones, and hence the structures 
in its course have to be supplied by other arteries. The ex- 
ternal carotid does a part of this work. Besides those into 
which it divides, the external carotid gives off six single 
branches, and a set to the parotid gland. The first three arise 
from the antero-internal aspect of the artery, low down and in 
the order given from below upward. The next two rise from 
the back of the artery higher up. 
I. Superior Thyroid. 
The superior thyroid, which is at first very superficial, being 
covered only by the platysma and fascia, forms a curve, first 
passing upward and inward, then downward and inward, crosses 
beneath the depressor muscles of the hyoid bone, and reaches 322 
DESCRIPTIVE ANATOMY. 
the upper part of the thyroid gland, to which it is distributed. 
It gives off the following branches: 
The infra-hyoid, which passes forward just beneath the hyoid 
bone, to be distributed to ipuscles and anastomose with its fel- 
low of the opposite side. 
The superior laryngeal, which passes forward on the thyro- 
hyoidean membrane and pierces it to be distributed to the mu- 
cous membrane of the larynx, anastomosing with its fellow. 
The crico-thyroid, which passes across the crico-thyroid mem- 
brane and gives branches which pierce it to reach the mucous 
membrane of the larynx, anastomosing with its fellows. 
The sterno-mastoid or superficial descending branch, which 
passes downward and outward across the common carotid to 
supply the sterno-mastoid. 
The terminal or thyroid branches, distributed to the thyroid 
gland. 
II. Lingual. 
The lingual artery is divided into four portions: 1, it de- 
scends obliquely inward, over the extremity of the hyoid bone 
covered only by the skin and platysma; 2, it passes forward 
along and above the hyoid bone, is crossed by the digastric 
and then covered by the hyo-glossus muscle; 3, it ascends to 
the under aspect of the tongue; 4, it runs forward on the under 
aspect of the tongue, under the name of the ranine artery. The 
first two portions lie on the middle constrictor of the pharynx. 
Its branches are three: 
The supra-hyoid, which runs inward along the upper border 
of the hyoid bone to be distributed to muscles and anastomose 
with its fellow. 
The dorsalis linguae, which ascends to the dorsum of the 
tongue along the posterior border of the hyo-glossus muscle to 
supply the back of the tongue mucous membrane and soft palate. 
The sublingual, which runs forward to the sublingual gland 
from the margin of the hyo-glossus and is distributed to that 
gland, to the mucous membrane of the mouth and to muscles. 
The ranine is the terminal branch of the lingual. It passes 
forward on the under surface of the tongue, beneath the mucous THE VASCULAR SYSTEM. 
323 
membrane is distributed to that organ and anastomoses with 
its fellow at the end of the tongue. 
III. Facial. 
The facial artery arises just above the hyoid bone and is 
divided into two portions, one while it is in the neck and the 
other after it reaches the face. The first portion passes for- 
ward and upward, through the submaxillary gland, to mount 
over the body of the lower jaw just at the anterior inferior 
angle of the masseter muscle and about one and one-half inches 
in front of the angle of the lower jaw. At its origin it is super- 
ficial, being covered only by the skin and platysma; but it soon 
enters the submaxillary gland and is crossed by the stylo-hyoid 
and posterior belly of the digastric. When it leaves the gland 
and mounts over the jaw it is again superficial, being covered 
only by the integument and platysma. Its pulsations can here 
be felt. The second portion of the artery has a tortuous upward 
and inward course over the face towards the angle of the mouth, 
thence along the side of the nose to terminate at the inner 
canthus of the eye as the angular artery. Its branches are di- 
vided into those given off below the jaw, five in number, and 
those on the face, also five in number. 
The inferior palatine, which ascends to the soft palate, ton- 
sils, Eustachian tube, stylo-pharyngeus, and stylo-glossus mus- 
cles. 
The tonsillar, which ascends to the tonsils. 
The submaxillary, which are from three to five in number, 
and are distributed to the submaxillary gland. 
The submental, which runs forward beneath the lower jaw 
and passing over the symphysis menti terminates by inosculat- 
ing with the inferior labial. It lies on the mylo-hyoid, supplies 
neighboring muscles and anastomoses with the submaxillary be- 
fore running over the chin. 
The muscular branches distributed to neighboring muscles. 
The five branches from the second portion are as follows: 
The muscular or buccal, which are branches to adjacent mus- 
cles. 324 
DESCRIPTIVE ANATOMY. 
The inferior labial, which runs forward beneath the skin of 
the lower lip, supplies muscles in its course and anastomoses 
with the submental inferior coronary, the inferior dental, and 
its fellow of the opposite side. 
The inferior coronary, which skirts the edge of the lower h'p, 
anastomoses with its fellow of the opposite side, with the mental 
branch of the inferior dental and with the inferior labial, and 
supplies muscles and glands in its course. 
The superior coronary, which skirts the edge of the upper 
lip, giving off a branch to the septum of the nose, arteria septi. 
This artery anastomoses with its fellow and supplies structures 
in its course. The arteria septi passes upward to ramify on 
the septum of the nose. 
The lateralis nasi, which is distributed to the side of the nose, 
inosculating with its fellow of the opposite side. 
The angular artery is the continuation of the facial. Passing 
up along side of the nose, it gives off small branches to the 
cheek and terminates by anastomosing with the nasal branch of 
the ophthalmic. 
The inferior labial and inferior coronary very frequently come 
off by a common trunk. Sometimes it is a common trunk which 
divides into the inferior and superior coronary arteries. 
IV. Occipital. 
The occipital branch of the external carotid passes upward 
and backward to the occipital groove of the temporal bone, be- 
neath the muscles attached to the mastoid process, thence mount- 
ing on the posterior aspect of the occipital bone and piercing 
the fascia which connects the cranial attachment of the trape- 
zius with the sterno-cleido-mastoid becomes superficial and is 
distributed to the back of the head. The hypoglossal nerve 
winds around it from behind forward, embracing the vessel be- 
hind, externally and in front. The artery crosses over the in- 
ternal carotid artery, the internal jugular vein, the pneumogas- 
tric and spinal accessory nerves. Its branches are: 
The sterno-mastoid, which, sometimes arising directly from 
the external carotid, descends to the sterno-mastoid muscle. THE VASCULAR SYSTEM. 
325 
The muscular branches to stylo-hyoid and digastric. 
Two small branches, auricular to the concha and meningeal to 
the membranes of the brain. 
The princeps cervicis, which passes down the neck, lying deep. 
It divides into a superficial branch, which passes beneath the 
splenius and inosculates with the superficial cervical of the 
transversa colli, and a deep branch which passes beneath the 
complexus to anastomose with the profunda cervicis. 
V. Posterior Auricular. 
The posterior auricular passes upward and backward be- 
hind the ear, and is distributed by an anterior branch to the 
auricle and by a posterior to the back of the head. It produces 
three branches, the stylo-mastoid, which enters the stylo-mas- 
toid foramen to be distributed to the ear; the auricular, which 
is distributed to the back part of the cartilage of the ear; the 
mastoid, which, passing over the sterno-mastoid, is distributed 
to the scalp behind and above the ear. 
VI. Parotidean Branches. 
The parotidean branches, four or five in number, are distri- 
buted in the parotid gland as the external carotid is passing 
through it. 
Ascending Pharyngeal. 
The ASCENDING pharyngeal branch springs from the ex- 
ternal carotid just at its origin and passes up beside the pharynx 
to the base of the skull, where it divides into a meningeal 
branch to enter the cavity of the cranium through the jugular 
foramen, a pharyngeal branch to adjacent parts of the pharynx, 
palatine and tympanic branches, to the soft palate and tympanic 
cavities and muscular branches to the prevertebral group. 326 
DESCRIPTIVE ANATOMY. 
The Temporal Artery. 
The temporal artery, one of the two terminal branches of 
the external carotid, begins where the external carotid forks in 
the parotid gland, behind the neck of the condyle of the lower 
jaw, and, emerging, mounts over the zygoma and divides about 
one and one-half inches above that point, where it lies on the 
temporal fascia, into an anterior and a posterior temporal. The 
anterior passes upward and forward, inosculating with the 
frontal and supra-orbital the posterior upward and backward 
to be distributed to the side of the head, and to inosculate with 
its fellow of the opposite side and with the occipital. These 
two are called the superficial temporal branches, since, as will 
appear hereafter, there are other and deeper temporal branches. 
It gives rise to four branches besides those in which it ter- 
minates : 
1. Transverse facial, which arises below the zygoma, and 
passes transversely forward on the masseter muscle parallel 
with Steno's duct. It anastomoses with the facial. 
2. Anterior auricular, to the front of the auricle. 
3. Orbital, which runs forward to the outer angle of the eye. 
4. Middle temporal, which plunges into the substance of the 
temporal muscle, where it is distributed. Its name is derived 
from its situation between the two superficial temporal arteries 
and the deep temporal which springs from another trunk. 
The Internal Maxillary. 
The internal maxillary is the larger of the two terminal 
branches of the external carotid. The course of the artery is 
divisible into three portions: 
The -first 'portion passes inward, forward, and upward behind 
the ramus of the inferior maxilla, between it and the internal 
lateral ligament to the lower border of the external pterygoid 
muscle. It is accompanied by the internal maxillary vein and 
the auriculo-temporal nerve, which lies above it. THE VASCULAR SYSTEM. 
327 
The second portion passes forward and upward between the 
internal pterygoid muscle within and the temporal and masseter 
muscles without. 
The third portion disappears into the spheno-maxillary fossa, 
between the two heads of the external pterygoid. Its branches 
are sixteen in number, as follows: 
First Portion-Four Branches. 1. The tympanic, which en- 
ters the tympanum through the fissure of Glaser and ramifies 
on the tympanic membrane, anastomosing with the Vidian and 
tympanic branches of the internal carotid. The deep auricular 
frequently arises with this branch, passes to the external audi- 
tory meatus, behind the temporo-maxillary articulation, and is 
distributed to the outer surface of the tympanic membrane. 
2. The meningea media, which ascends to enter the cavity 
of the cranium through the foramen spinosum. It then divides 
into an anterior and a posterior branch. The anterior passes 
upward and forward over the great wing of the sphenoid, 
grooves the anterior inferior angle of the parietal, and divides 
into branches which ramify over the dura. The posterior 
branch passes over the squamous portion of the temporal and 
divides into branches on the occipital. These branches anasto- 
mose with each other and with the anterior and posterior menin- 
geal. They supply the dura and the bone. 
3. The meningea parva, which enters the cavity of the cra- 
nium through the foramen ovale and supplies the Gasserian 
ganglion and dura. 
4. The inferior dental, which descends to enter the dental 
foramen of the inferior maxilla and runs forward in the bone, 
giving a branch to each fang of every tooth in the lower jaw. 
It gives off the lingual branch near its origin, which branch ac-* 
companies the nerve of the same name to the mucous membrane 
of the mouth. Just before entering the dental foramen it gives 
off a branch called mylo-hyoidean; and when it reaches the 
mental foramen it divides, sending a branch called mentalis 
through the mental foramen, while another, called the incisive, 
continues its course in the bone. The mylo-hyoidean passes in 
the groove of that name, and supplies the mylo-hyoid muscle. 328 
DESCRIPTIVE ANATOMY. 
Second Portion. Six branches are derived from this portion 
of the artery. The deep temporal, two in number, occupy the 
anterior and posterior portions of the temporal fossa. They 
anastomose with the superficial temporal arteries and supply 
the temporal muscle. The pterygoid branches, as the name in- 
dicates, supply the pterygoid muscles. The masseteric branch 
runs through the sigmoid notch and supplies the masseter from 
its deep surface. The buccal passes forward between the in- 
ternal pterygoid and the lower jaw and supplies the buccinator. 
It anastomoses with the facial. 
Third Portion. 1. The superior dental, or alveolar, which 
descends upon the tuberosity of the superior maxilla and sends 
its branches through small foramina in the bone to supply the 
molar and bicuspid teeth. 
2. The infra-orbital, which runs forward along the canal in 
the floor of the orbit, sending branches downward to the front 
teeth of the upper jaw and emerges through the infra-orbital 
foramen to supply adjacent parts on the face. 
3. The descending palatine, which descends along the pos- 
terior palatine canal to emerge in the palate through the 
posterior palatine foramen and send a branch forward in a 
groove seen on the side of the hard palate (called the anterior 
palatine canal), which reaches the floor of the nose through the 
anterior palatine foramen. 
4. The Vidian, which passes backward along the pterygoid 
canal, and, like the pterygo-palatine, is distributed to the mucous 
membrane of the pharynx and Eustachian tube. 
5. The pterygo-palatine, which runs backward in the pterygo- 
palatine canal to the pharynx, Eustachian tube and neighboring 
parts. 
6. The spheno-palatine, which enters the nose through the 
spheno-palatine foramen and divides into two branches, one 
being distributed to the septum and the other to the mucous 
membrane of the outer wall and antrum maxillare. THE VASCULAR SYSTEM. 
329 
The Right Subclavian. 
The right subclavian artery is one of the two terminal 
branches of the arteria innominata, the other being the right 
common carotid. It commences behind the upper border of the 
right sterno-clavicular articulation, arches upward and qut- 
ward, passing between the scaleni muscles; then turns down- 
ward and outward, and terminates by becoming the auxiliary 
at the junction of the outer one-third with the inner two-thirds 
of the shaft of the clavicle on the outer border of the first rib. 
It is thus seen that it forms a bow, the highest part of the arch 
being that which passes between the scaleni muscles. This war- 
rants the subdivision of the artery into three portions. 
The first portion commences by a branch of bifurcation of 
the arteria innominata and terminates at the inner border of 
the scalenus anticus; the second lies behind the scalenus anticus; 
and the third portion extends from the outer border of the 
scalenus anticus to the termination of the artery in the axilla 
at the outer border of the first rib. This third portion is itself 
sometimes subdivided into that part which lies between the 
scalenus anticus and the clavicle and the part which lies behind 
the clavicle, but the division is unnecessary. 
Relations. The coverings of this artery are the skin, super- 
ficial fascia, platysma myoides muscle, one layer of the deep 
cervical fascia, the sterno-cleido-mastoid muscle, with the sec- 
ond layer of deep cervical fascia, the clavicle anticus muscle, 
the posterior belly of the omo-hyoid muscle, the clavicle and the 
subclavius muscle. It is better to take the relations of the 
artery as a whole; and then consider them with reference to 
the various portions of the vessel. Thus, starting from within 
and passing outward on the anterior face of the artery, we 
find the pneumogastric nerve, with its recurrent laryngeal 
branch, external to that the internal jugular vein, then the 
phrenic nerve, then the scalenus anticus muscle, then the supra- 
scapular vein and artery, the nerve to the subclavius and the 
subclavius muscle. More superficially, just beneath the skin, 
are the thoracic branches of the cervical plexus. Below it are 
its vein, the recurrent laryngeal nerve, the lung and pleura, 330 
DESCRIPTIVE ANATOMY. 
and the first rib. Behind, the recurrent laryngeal, the cervical 
portion of the sympathetic nerve, the vertebrae, the scalenus 
posticus muscle, and the brachial plexus of nerves. Above, the 
brachial plexus and the omo-hyoid muscle; and to its inner side, 
the right common carotid. 
To consider the different parts separately: 
The first portion is covered throughout by the integument, 
platysma, sterno-cleido-mastoid; and, at its commencement, by 
the right sterno-clavicular articulation, the sterno-hyoid and 
sterno-thyroid muscles. Superficial branches of the cervical 
plexus also pass over it. Crossing it in front are the pneumo- 
gastric nerve, giving off here its recurrent laryngeal branch; 
external to this, the internal jugular vein; and external to this, 
usually the phrenic nerve. The course of the phrenic is down- 
ward and slightly inward upon the anterior face of the scalenus 
anticus muscle. Occasionally it continues on that muscle until 
it passes beyond the artery, but generally it drops from the 
muscle to the artery to become an anterior relation of the latter. 
In front near its beginning is the right vertebral vein. Just 
as the internal jugular vein crosses the front of the artery it 
communicates with the subclavian vein to form the right vena 
innominata. Hence the junction of these two veins would lie 
below on a plane anterior and slightly to the outer side of the 
first portion of the subclavian. The pneumogastric here gives 
off the recurrent laryngeal, which is first in front, then below, 
then behind the artery. To the inner side at its commencement 
is the right common carotid. Behind it is the recurrent laryn- 
geal, and the cervical portion of the sympathetic, the cardiac 
branches of which cross in front. Below, the artery rests upon 
the lung and the pleura. The pleura of the right side extends 
upward into the root of the neck above the level of the first 
rib, so that the artery makes an impression upon the dome of 
the pleura, and a portion of that membrane lies behind the 
artery as well as beneath it. 
The second portion forms the top of the bow; and runs trans- 
versely outward. It runs behind the scalenus anticus muscle; 
and is co-extensive with its breadth. 
In front are the integument, superficial fascia, the platysma, 
first layer of deep cervical fascia, the sterno-cleido-mastoid, THE VASCULAR SYSTEM. 
331 
second layer of deep cervical fascia, and branches of the cer- 
vical plexus extending superficially over the clavicle. Occa- 
sionally on its front is the phrenic nerve. The super-scapular 
and the transversa colli branch of the subclavian pass across 
the front of the scalenus anticus muscle; and should be con- 
sidered in all operations in this situation. The brachial plexus 
of nerves lies behind and above the artery, separating it from 
the scalenus posticus muscle. Below and behind are found the 
pleura and the lungs. The subclavian vein is not a relation of 
the artery, lying some distance below it and separated from it 
by the scalenus anticus. 
The third portion is the downward and outward part, ex- 
tending from the outer edge of the scalenus anticus to the outer 
border of the first rib, and lying in its lower portion between 
the clavicle and the first rib. It is covered entirely by the 
skin, fasciae and the platysma; and, to a slight extent, in many 
cases, by the outer edge of the sterno-cleido-mastoid; and, in 
a few cases, where this muscle has a redundant origin, the third 
portion of the artery is covered completely by it. The artery 
lies in the triangular space bounded above by the omo-hyoid, 
internally by the sterno-cleido-mastoid, and below by the clavicle. 
This space is covered over by a rather dense layer of the deep 
cervical fascia, which is of course one of the coverings of the 
vessel. Crossing in front of it is the supra-scapular artery, a 
branch of the subclavian itself, which passes outward just 
beneath the upper border of the clavicle. This artery is accom- 
panied by its own vein. Just beneath the platysma there crosses 
in front of the artery, from above, the external jugular vein, 
which descends the neck lying just behind the outer edge of 
the sterno-cleido-mastoid muscle; and, after having received* 
on the front of the artery the super-scapular and transverse 
cervical veins, terminates in the subclavian on the outer side 
of the scalenus anticus. 
The subclavius muscle and nerve are in front. In front of 
these lie superficial branches of the cervical plexus. Owing 
to the curve in the course of the artery, what has heretofore 
been called its upper aspect now becomes its external. The 
brachial plexus of nerves has been described as being an ex- 332 
DESCRIPTIVE ANATOMY. 
ternal relation, though the plexus lies on a plane posterior to 
the artery as well as to its outer side. The omo-hyoid lies above 
and to the outer side, in front of the plexus. To the inner side 
is the subclavian vein, which is in contact with the vessel for 
only a short distance before its termination. The vein, it will 
be observed, is a relation of the first and third portions only; 
that is, it is in contact with the outer front aspect of the first 
portion at its commencement, and with the inner front aspect 
of the third portion at its termination, bearing no relation to 
the second portion, hence it presents the same relation which 
a string bears to a bent bow. At the very commencement of 
this portion it lies upon the pleura, so that it will be seen that 
the pleura lies below and behind all three of the portions of 
the artery, though for the third portion the relation is only 
a momentary one, the first rib quickly separating the two 
structures. 
The ligation of this vessel is preferably performed in the 
third portion of its course. 
Branches. 
Vertebral. 
Thyroid Axis 
Inferior Thyroid. 
Supra-Scapular. 
Internal Mammary. 
Superior Intercostal. 
Transversa Colli. 
Profunda Cervicis. 
These seven branches usually rise by four trunks-the ver- 
tebral, thyroid axis, internal mammary, and the common trunk 
for the superior intercostal and cervicalis profunda. 
Vertebral. 
The vertebral is the first and largest branch of the sub- 
clavian. It arises from the posterior aspect of the first portion 
of the artery, and enters the foramen in the transverse process 
of the sixth cervical vertebra, usually. Occasionally it passes 
to the fifth; but, though the seventh is perforated, the vertebral THE VASCULAR SYSTEM. 
333 
artery never enters it. It passes upward through the foramina 
of the transverse processes, winds backward around the superior 
articular process of the atlas, enters the cavity of the cranium 
through the foramen magnum, and at the lower border of the 
pons Varolii unites with its fellow of the opposite side to form 
a single trunk, called the basilar artery, which runs upward 
and forward to the anterior border of the pons, where it divides 
into two terminal branches, the posterior cerebral, one on either 
side. At its origin the internal jugular vein and the inferior 
thyroid artery lie in front of it. On the left side, while lying 
between the scalenus anticus and longus colli muscles, the tho- 
racic duct passes in front of it. Besides its terminal branches it 
gives off the following branches: 
1. The lateral spinal, which are given off, as the artery 
ascends the neck, and enter the inter-vertebral foramina. They 
there divide into two branches-one for the bodies of the ver- 
tebrae and the other for the spinal cord and its membranes. 
That for the spinal cord reaches it along the roots of the spinal 
nerves, while the branch for the bodies of the vertebrae divides 
into an ascending and a descending branch, anastomosing with 
similar branches coming from above and below, and forming 
a chain of anastomoses along the spinal column, from which 
branches are given off to the bodies of the vertebrae, com- 
municating with the chain of the opposite side. 
2. The muscular branches are unimportant. They come from 
the lower portion of the artery, and are distributed to the 
cervical muscles. 
3. The posterior meningeal are small branches distributed 
to the dura mater of the cranium. 
4. The anterior spinal arises near the termination of the 
vertebral, unites with its fellow of the opposite side, and passes 
downward on the middle of the spinal cord, where it receives 
communications from the lateral spinal branches, before men- 
tioned, and forms a continuous vascular channel down the an- 
terior aspect of the cord. 
5. The posterior spinal winds around the medulla, unites with 
its fellow of the opposite side, passes down behind the posterior 
roots of the spinal nerves, and receives similar branches from 334 
DESCRIPTIVE ANATOMY. 
the lateral spinal. This also forms a branch passing down the 
spinal cord. 
6. The posterior inferior cerebellar arises just before the 
termination of the vertebral, and passing across the lateral 
aspect of the medulla, winds around the inferior portion of the 
cerebellum, to which it is distributed. 
The basilar artery is formed by the junction of the two ver- 
tebral arteries above the middle of the medulla oblongata; and, 
after passing upward on the lower surface of the pons Varolii, 
it terminates on the upper border of that body by dividing into 
two branches, the posterior cerebral arteries. It gives off the 
following branches: 
1. The transverse, which are numerous small branches given 
off to each side of the pons Varolii. The internal auditory is a 
slender branch going to the inner meatus. 
2. The anterior inferior cerebellar, or anterior cerebellar, 
which arises soon after the origin of the basilar, and passing 
across the pons a little below its centre, reaches the anterior 
border and lower surface of the cerebellum, where anastomosing 
with the posterior inferior cerebellar, it is distributed to that 
organ. It is in reality scarcely more than one of the transverse 
branches. 
3. The superior cerebellar, which, passing across the upper 
border of the pons, passes into the fissure between the upper 
border of the cerebellum and the cerebrum, and ramifies upon 
the upper surface of the cerebellum. 
In addition to these way-side branches, the basilar artery 
gives off the following terminal: 
The posterior cerebral also winds around the outer border of 
the pons, passing to the inner surface of the posterior lobe of 
the cerebrum, to which it is distributed, anastomosing with the 
other cerebral arteries. These vessels anastomose with the 
posterior communicating branches of the internal carotid, thus 
completing the formation of the circle Willis, described with 
the internal carotid. From the two are given off postero-median 
and lateral ganglionic branches for the optic thalami, which 
form the posterior perforated space; posterior choroid to the THE VASCULAR SYSTEM 
335 
choroid plexus; and temporal and occipital branches for these 
lobes of the cerebrum. 
Thyroid Axis. 
The thyroid axis is a short thick trunk, which arises from 
the upper portion of the subclavian, just at the inner border 
of the scalenus anticus muscle. It almost immediately divides 
into three branches: the inferior thyroid, the suprascapular, 
and the transversa colli. 
Inferior Thyroid. 
The inferior thyroid, the branch from which the axis re- 
ceives its name, first passes vertically upward for a distance of 
an inch and one-half or two inches. It then turns inward, 
crossing behind the sheath of the common carotid artery to 
reach the thyroid gland. It gives off branches, or twigs, called 
laryngeal, tracheal, and oesophageal, which are distributed to 
the structures named: the larynx, the trachea and the oeso- 
phagus. Just as it makes its transverse, horizontal turn there 
springs off a large branch, called the cervicalis ascendens, which 
passes upward on the anterior tubercles of the transverse pro- 
cesses to be distributed to muscles and glands in the neck. 
Supra-scapular. 
The SUPRA-SCAPULAR, the next most constant branch, passes 
outward across the scalenus anticus muscle, where it is a dis- 
tant relation of the second portion of the subclavian. It then 
turns downward until it reaches the clavicle, behind which it 
passes outward over the scapula, crossing in its course the 
third portion of the subclavian. It passes over the transverse 
ligament of the scapula to reach its dorsum in the supra-spinous 
fossa, where it gives off branches to the bone, to the supra- 
spinatus muscle, and a branch which, winding around the an- 
terior border of the spine, enters the infra-spinous fossa, to 
communicate with vessels in that situation, chiefly the dorsalis 
scapulae branch of the auxiliary. DESCRIPTIVE ANATOMY. 
336 
Transversa Colli. 
Next to the inferior thyroid, the transversa colli is the 
largest of the branches of the thyroid axis, and the least fre- 
quent of its progeny. It passes across the side of the neck over 
the scalenus anticus muscle, above the level of the second por- 
tion of the subclavian, very frequently passing between some 
of the cords of the brachial plexus of nerves. On reaching the 
anterior edge of the trapezius it divides into two branches: 
the cervicalis sup er facialis and the posterior scapular. The 
cervicalis superficialis runs upward to anastomose with the 
superficial branch of the arteria princeps cervicis from the occi- 
pital. The posterior scapular, much larger than the preceding, 
passes to the vertebral border of the scapula; and descending 
along it, anastomoses with the dorsalis scapulae branch from the 
subscapular artery. 
Internal Mammary. 
The internal mammary arises from the lower aspect of the 
subclavian at the inner edge of the scalenus anticus, and fre- 
quently directly opposite the origin of the vertebral. It passes 
downward upon the costal cartilages about half an inch from 
the edge of the sternum to the diaphragm, where it divides into 
its two terminal branches: the superior epigastric and musculo- 
phrenic. It is accompanied by satellite veins, lying upon either 
side. At its origin it is covered by the internal jugular and 
subclavian veins, and has crossing it the phrenic nerve. Its. 
branches are: 
1. The comes nervi phrenici, which arises at the upper por- 
tion of the vessel. It is a long and slender branch; and accom- 
panies the phrenic nerve, having the same relations as that 
nerve, and terminates by anastomosing with the other arteries 
of the diaphragm. 
2. The anterior intercostal, which are given off to the inter- 
costal spaces, which the internal mammary passes. Each pass- 
ing outward, soon divides into two branches, one for the upper 
and the other for the lower border of the ribs. These branches 
occasionally spring separately from the artery. They first lie THE VASCULAR SYSTEM. 
337 
between the intercostal muscles and the pleura; and then be- 
tween the two intercostal muscles. They anastomose with the 
intercostal branches of the thoracic aorta. 
3. The perforating branches are usually six in number, cor- 
responding to the number of intercostal spaces. They pass 
forward to the front of the thorax; then running outward, are 
distributed to the muscles, and in the female, chiefly to the 
mammary gland. 
4. The mediastinal, small and unimportant branches, which 
supply the structures of the anterior mediastinum. 
5. The pericardial branches, which are about the size of the 
mediastinal and are distributed to the pericardium. 
These are the way-side branches of the vessel. Of the two 
terminal branches, the larger, the superior epigastric, leaves 
the thoracic cavity behind the seventh costal cartilage. It en- 
ters the sheath of the rectus muscle; and continuing its course 
downward, anastomoses with the inferior epigastric, a branch 
which springs from the external iliac. This is the longest anas- 
tomosis in the body, establishes a connection between the ar- 
teries in the upper and the arteries in the lower extremity, and 
renders it conceivable that the abdominal aorta might be ligated 
without immediate death. It gives off branches to the muscles 
in its course. 
The musculo-phrenic follows the curvature of the lower ribs. 
It passes downward and outward, giving off intercostal branches 
similar to those given off from the trunk of the internal mam- 
mary itself, and performing the same service, and in addition 
giving off a branch to the diaphragm. 
Superior Intercostal. 
The superior intercostal and profunda cervicis usually 
spring by a common trunk from the second portion of the sub- 
clavian artery, though occasionally they rise from the third 
portion, and occasionally by separate trunks. The superior in- 
tercostal curves backward from the apex of the pleura until 
it reaches the head of the first rib, when it changes its direc- 338 
DESCRIPTIVE ANATOMY. 
tion, and supplies the first intercostal space after the manner 
of all intercostal arteries. 
Profunda Cervicis. 
The profunda cervicis passes backward between the trans- 
verse process of the seventh cervical vertebra and the first rib, 
or occasionally the transverse process of the first dorsal ver- 
tebra, and passes upward in the neck to inosculate with the 
deep division of the princeps cervicis branch of the occipital 
artery, establishing a collateral circulation between the carotid, 
and the subclavian arteries. 
The Axillary Artery. 
The axillary is the second subdivision of the artery of 
the upper extremity. It begins by being a continuation of the 
subclavian where that artery ceases at the outer border of the 
first rib, passes downward and outward from the upper lateral 
aspect of the chest, corresponding to the first four ribs, and 
down the inner aspect of the arm to terminate at the lower 
border of the tendons of the latissimus dorsi and teres major 
muscles by becoming the brachial artery. The direction of the 
artery will, of course, vary with the position of the limb; and 
its relations are studied with the limb in the anatomical position. 
Relations. The artery is covered throughout by the pectoralis 
major, and through part of its extent by the pectoralis minor, 
and costo-coracoid membrane, and of course by the skin, super- 
ficial and deep fascias. Throughout its course its vein lies to 
its inner front aspect. The brachial plexus of nerves is a con- 
tinuous relation, lying to its outer side in the beginning, on 
all three sides in the second portion of its course, while the 
terminal branches bear various relations to the third portion 
of the artery. The relationship to the pectoralis minor war- 
rants the subdivision of the vessel into three portions, each 
of which should be studied in detail. The first portion extends 
from the beginning of the vessel to the upper border of the 
pectoralis minor muscle; and is contained in the thoracic sur- THE VASCULAR SYSTEM. 
339 
gical triangle. The second portion commences at the upper 
border of the pectoralis minor, and terminates at its lower 
border by becoming the third portion. The third portion, com- 
mencing at the lower border of the pectoralis minor, and ter- 
minates at the lower border of the tendons of the latissimus 
dorsi and teres major by becoming the brachial artery. 
The first portion is covered by the skin, superficial and deep 
fascia, and the pectoralis major muscle. It is crossed by the 
costo-coracoid membrane; and by the outer anterior thoracic 
nerves, and the acromio-thoracic and cephalic veins. Internally 
it has the second serration of the serratus magnus, the first rib, 
and the first intercostal muscle. Behind, it lies upon the sub- 
scapularis. Its vein is internal and in front, while the brachial 
plexus of nerves lies to its outer side and slightly behind it. 
More superficially, in the internal between the pectoralis major 
and the deltoid, it is crossed by the cephalic vein. Behind it 
is the respiratory nerve of Bell (posterior thoracic) and the 
inner anterior thoracic nerves. 
The second portion is covered by the skin, superficial and 
deep fascias, pectoralis major and pectoralis minor. This is 
the portion crossing from the chest to the arm; and corres- 
ponds to the position of the third serration of the serratus 
magnus. Behind, it rests upon the subscapularis. The chords 
of the brachial plexus are here divided into three: internal, 
external, and posterior, which bear the corresponding relations 
to the second portion of the axillary, while the vein is still in- 
terior and anterior. 
The third portion is covered by the pectoralis major, and a 
strong fascia, which covers over the axillary space. Posteriorly 
it rests upon the tendons of the latissimus dorsi and teres 
major and subscapularis muscles, while external to it is the 
coraco-brachialis and the short head of the biceps. At the begin- 
ning of this portion the brachial plexus breaks up into its ter- 
minal branches; and all of these branches bear some relation 
to the vessel. The external and internal cords each give off a 
branch, which unite to form the median nerve on the front 
of its commencement. This nerve immediately drops to the 
outer side of the vessel; and maintains that relation to its ter- 340 
DESCRIPTIVE ANATOMY. 
mination. The outer cord also gives off the musculo-cutaneous, 
which is an external relation for a short distance, then, plung- 
ing into the fibres of the coraco-brachialis, ceases to be a rela- 
tion of the axillary. The inner cord, after contributing one root 
to the median, gives off the ulna and internal cutaneous and 
lesser internal cutaneous nerves, all of which are fixed internal 
relations. To the inner front aspect is the vein. The ulnar 
nerve is between the vein and artery; the lesser internal cuta- 
neous internal to the vein and the internal cutaneous to the 
inner front aspect of the artery. Behind, it rests upon the cir- 
cumflex nerve and the subscapular artery for a short distance, 
while the last cord of the plexus, the musculo-spiral, is a con- 
tinuous posterior relation. 
Branches. 
Superior Thoracic 
Acromial Thoracic 
Long Thoracic 
Subscapular 
Thoracica Alaria 
Posterior Circumflex 
Anterior Circumflex. 
The point of origin of the branches of the axillary is very 
uncertain, and no perfectly accurate description applying to 
all cases can be written. Usually the short thoracic and the 
acromial thoracic arise from the first portion, the thoracica 
alaria and long thoracic from the second, and the subscapular 
and anterior and posterior circumflex from the third. Some- 
times they will rise by common branches; and almost any ar- 
rangement may be anticipated in the origin of the branches of 
this vessel. 
Superior Thoracic. 
The superior thoracic usually arises by a common trunk 
with the acromial thoracic. It passes inward along the upper 
border of the pectoralis minor, then between the two pectoral 
muscles to be distributed to the upper intercosal muscles and 
a part of the serratus magnus, anastomosing with the intercostal 
arteries. It frequently sends branches to the pectoral muscles, 
and occasionally to the mammary gland. THE VASCULAR SYSTEM. 
341 
Acromial Thoracic. 
The acromial thoracic, usually arising by a common trunk 
with the short thoracic, arises just above the pectoralis minor, 
passes directly forward to pierce the costo-coracoid membrane, 
and divides into three branches, which from their distribution 
have been called the acromial, the pectoral, and the descending 
humeral. 
The pectoral passes between the pectoralis major and minor, 
and is distributed, in the main, to the mammary gland, some 
branches going to the pectoral muscles. 
The acromial, though the smallest branch, gives its name to 
the trunk, and passes outward across the acromion process, 
sometimes piercing the deltoid muscle, where it anastomoses 
with the circumflex and suprascapular arteries, forming the 
plexus around the acromion process. 
The descending branch passes into the interval between the 
deltoid and pectoralis major muscles, and is distributed to the 
muscles in its course, anastomosing with the plexus formed by 
the preceding branch. 
Thoracica Alaria. 
The thoracica alaria are not infrequently branches from 
the long thoracic. They sometimes arise separately from the 
trunk; and are distributed mainly to the lymphatics, integu- 
ment and fascia of the axilla. 
Long Thoracic. 
The LONG thoracic arises either alone, or by a common trunk 
with the preceding, passing between the pectoral muscles and 
the serratus magnus to reach the lateral aspect of the chest. 
It gives branches to the pectorals and to the serratus magnus, 
anastomoses with the intercostal arteries, and occasionally 
gives a large branch to the mammary gland. DESCRIPTIVE ANATOMY. 
342 
Subscapular. 
The SUBSCAPULAR is usually the largest branch of the axillary 
artery, arising generally opposite the lower border of the sub- 
scapularis. It runs downward and inward, following the edge 
of that muscle, supplies it, the teres major, the latissimus dorsi, 
and serratus magnus, and gives branches to structures in the 
axillary space. At the inferior angle of the scapula it anasto- 
moses with the posterior scapular, while the branches which 
pass to the thoracic wall anastomose with the intercostal and 
long thoracic arteries. From an inch to an inch and one-half 
after its origin it gives off a large branch, called the dorsalis 
scapulae, which passing through the triangular space between 
the teres major below, the teres minor above, and long head 
of the triceps externally, curves around the axillary border of 
the scapula, and reaches the infraspinous fossa, where it is 
distributed to that fossa and to the infraspinatus muscle, anas- 
tomosing with the suprascapular and the posterior scapular ar- 
teries. It also supplies the teres minor, and sometimes gives a 
branch to the teres major muscle. 
Anterior Circumflex. 
The anterior CIRCUMFLEX, a very small vessel, frequently 
arises by a common trunk with the posterior, or it may arise 
from the subscapular. It passes beneath the coraco-brachialis 
and short head of the biceps muscle, passes over the bicipital 
groove; and gives off a branch to the shoulder joint, while the 
remainder of the artery winds around the neck of the humerus, 
and anastomoses with the posterior circumflex. 
Posterior Circumflex. 
The POSTERIOR CIRCUMFLEX, quite a large vessel, arises from 
the third portion of the axillary below the subscapularis muscle, 
passes through the quadrilateral space bounded externally by 
the shaft of the humerus, internally by the long head of the 
triceps, above by the teres minor, below by the teres major, THE VASCULAR SYSTEM. 
343 
winds around the back of the humerus, and passing beneath the 
deltoid, breaks up into a large number of branches, to be dis- 
tributed to that muscle throughout its deep surface. In addi- 
tion to this work, it gives off branches to the head of the humerus 
and the shoulder joint, and some axillary branches, while the 
continuation of the artery anastomoses with the anterior cir- 
cumflex, completing the vascular zone around the upper ex- 
tremity of the humerus. 
Frequently this artery arises by a common trunk with the 
anterior circumflex, each artery then pursuing its usual course. 
The two anastomose with each other, with the suprascapular 
and the dorsalis scapulae, thus establishing a complete arterial 
zone around the shoulder. 
Brachial Artery. 
The brachial is the third subdivision of the artery of the 
upper extremity. It begins by being a continuation of the 
axillary at the lower border of the tendons of the latissimus 
dorsi and teres major and passing downward and outward ter- 
minates half an inch, or a finger's breadth, below the middle 
of the front of the elbow-joint by dividing into the ulnar and 
radial arteries. It lies first on the inner side of the arm and 
then on the front, so that in order to check the circulation by 
pressure, in the first part of its course the force must be di- 
rected outward and backward, and in the second part directly 
backward. 
Relations. The muscular relations are as follows: To its 
outer side, at first, is the lower half of the coraco-brachialis and 
the short head of the biceps, and when this relation is lost by 
the insertion of the muscle, its place is taken by the biceps, 
whose belly, when the muscle is bulky, overlaps the artery. At 
the bend of the elbow it lies beneath the slip given off by the 
biceps. To the inner side are the skin and fascias. In the 
first part of its course it lies on the internal intermuscular sep- 
tum which separates it from the inner head of the triceps, and 
in the lower part on the branchialis anticus which separates it 
from the shaft of the humerus and front of the elbow joint. 344 
DESCRIPTIVE ANATOMY. 
Its relations to cords are as follows: 
It is accompanied by satellite veins, one on either side, the 
one on the inner side being the larger. These veins are fre- 
quently united by transverse branches crossing the front of 
the artery. 
To its inner side are the basilic vein and the internal cuta- 
neous nerve. Both vein and nerve, for the upper half of the 
artery, are covered by the investing fascia of the arm; but as 
the structures pass downward, they both pierce that fascia and 
become superficial and are internal to and in front of the 
artery. 
The median nerve lies on the outer side of the artery for its 
upper third, then crosses it, usually in front, about the middle 
of the arm is an anterior relation for its middle third, and be- 
comes a continuous internal relation for the lower third. In 
some cases the nerve crosses behind and is a posterior relation 
for the middle third, the other relations remaining unchanged. 
The ulna nerve is a postero-internal relation of the brachial 
for the upper one-half of its course, when it leaves that artery 
to pass to the back of the elbow joint. For a few inches the in- 
ferior profunda artery, accompanying the ulna nerve, bears also 
a posterior internal relation to the brachial. The musculo-spiral 
nerve and the superior profunda artery are momentary posterior 
relations above. 
Brachial at the Elbow. 
These relations are of such importance that they must be 
given separately. It lies on the middle of the joint upon the 
brachialis anticus, with a satellite vein on either side. On its 
outer side is the tendon of the biceps muscle; on its inner side 
the median nerve. In front of it is the bicipital fascia and 
upon that fascia are found the terminal branches of the internal 
cutaneous nerve and the median basilic vein, which unites with 
the common ulnar to form the basilic. The artery here lies in 
a triangle bounded internally by the pronator radii teres, ex- 
ternally by the supinator longus, and above by a line drawn 
from one condyle of the humerus to the other. THE VASCULAR SYSTEM. 
345 
Branches. 
Superior Profunda 
Anastomotica Magna 
Inferior Profunda 
Muscular. 
Superior Profunda. 
The superior profunda arises from the upper part of the 
brachial, and passes downward and outward. After piercing 
the inter-muscular septum, it winds around the humerus in the 
musculo-spiral groove, accompanying the nerve of that name; 
and on reaching the outer border of the humerus, divides into 
two branches. One of these pierces the external inter-muscu- 
lar septum; and continues downward in the interval between 
the supinator longus and the brachialis anticus to anastomose 
with the recurrent branch from the radial, while the other 
branch continues its course behind the external inter-muscu- 
lar septum to anastomose with the posterior interosseous recur- 
rent and also with the anastomotica magna. 
Inferior Profunda. 
The inferior profunda arises a little above the middle of 
the vessel, just below the superior. It immediately seeks the 
ulnar nerve; and with that nerve pierces the internal inter-mus- 
cular septum to pass to the inner back part of the elbow joint, 
where it anastomoses with the anastomotica magna and the 
posterior ulnar recurrent. 
Anastomotica Magna. 
The anastomotica MAGNA arises near the termination of the 
brachial, about two inches above the elbow joint. It runs di- 
rectly inward to the inner aspect of the arm, anastomoses with 
the anterior ulnar recurrent, pierces the inter-muscular sep- 
tum, passes outward beneath the triceps, or sometimes through 
the fibres of that muscle, anastomoses with the inferior pro- 
funda and the posterior ulnar recurrent on the inner aspect 
of the elbow joint, with the posterior branch of the superior 346 
DESCRIPTIVE ANATOMY. 
profunda upon the outer aspect of the elbow joint, and with 
the posterior interosseous recurrent. Thus the only branch 
forming the vascular circle around the elbow joint with which 
the anastomotica magna does not anastomose is the radial re- 
current. 
The anastomotica magna is thus the chief artery in complet- 
ing the chain around the elbow. Passing inward it receives a 
communication from the anterior ulnar recurrent: then from 
the inferior profunda and posterior ulnar recurrent; then, on 
the outer side of the arm, from the posterior branch of the 
superior profunda, whose anterior branch has already inoscu- 
lated with the radial recurrent. 
Muscular. 
The MUSCULAR branches are numerous twigs distributed 
along the course of the parent artery. 
The Arteries of the Forearm. 
The arteries of the forearm are the radial and ulnar and their 
branches. 
Radial Artery on the Forearm. 
The radial artery, one of the two terminal branches of the 
brachial, begins where that artery divides about half an inch 
below the middle of the front of the elbow, and passes down- 
ward with such an inclination outward as to bring it to the 
outer side of the front of the wrist joint, where it lies on the 
front of the styloid process of the radius, terminating as the 
radial artery of the forearm by becoming the radial artery of 
the wrist. 
Relations. To the outer side it has throughout its course the 
brachio-radialis, whose belly overlaps it. With this exception 
this artery is superficial. To its inner side is first the pronator 
radii teres, and, when that muscle is inserted, its place is taken 
by the flexor carpi radialis which remains to the inner side. THE VASCULAR. SYSTEM. 
347 
Behind it lie the tendons of the biceps, the supinator brevis, 
the insertion of the pronator radii teres, a part of the origin 
of the flexor sublimis digitorum, a portion of the flexor longus 
pollicis, and the pronator quadratus. Below these is the front 
of the shaft of the radius. 
It is accompanied by satellite veins, one on either side, and 
in the middle third of its course has the radial nerve to its outer 
side. The nerve in the upper third is too far away to be con- 
sidered a relation, while in the lower third it passes beneath 
the tendon of the brachio-radialis and disappears on the back 
of the forearm. 
Ulnar Artery on the Forearm. 
The ulnar artery, the larger of the two terminal branches 
of the brachial, begins where that artery terminates about half 
an inch below the middle of the front of the elbow, by dividing 
into itself and the radial, and passes first downward and in- 
ward for the upper third of its course, to the inner side of the 
front of the forearm and then turns vertically downward to 
reach the inner side of the front of the wrist, where it ter- 
minates as the ulnar artery of the forearm by becoming the 
ulnar artery of the hand. 
Relations. In the first part of its course, while it is passing 
downward and inward, it lies beneath four muscles, viz.: prona- 
tor radii teres, flexor carpi radialis, palmaris longus and flexor 
sublimis digitorum-all the muscles of the superficial group ex- 
cept the flexor carpi ulnaris. When it emerges from beneath 
these muscles it descends with the tendon of the flexor carpi 
ulnaris to its inner and of the flexor sublimis digitorum to its 
outer side. In its upper portion it lies on the brachialis anticus 
and in its lower portion on the flexor profundus digitorum. 
It is accompanied by satellite veins, one to either side, and 
for its lower two-thirds has to its inner side the ulnar nerve. 
In its upper part it is crossed by the median nerve. 348 
DESCRIPTIVE ANATOMY. 
Ulnar Artery in the Hand. 
When the ulnar artery reaches the wrist it continues its 
course into the palm of the hand, lying close to and on the outer 
side of the pisiform bone and on the anterior annular ligament. 
After passing down a short distance into the palm, it turns out- 
ward and runs across the palm of the hand to its outer side, 
being covered only by the skin and fascia and lying on the 
flexor tendons and on the origin of the muscles of the little 
finger, and on the divisions of the median and ulnar nerves 
to inosculate with the radialis indicis and form the superficial 
palmar arch. This arch is sometimes completed by the super- 
ficialis volae, and, rarely, by the princeps pollicis. Its course 
across the palm is known as the superficial palmar arch (arcus 
volaris superficialis) and though its direction is not transverse, 
it is more or less clearly defined by a transverse line across the 
palm drawn from the bottom of the interval between the thumb 
and index finger. The ulnar nerve continues its relation to the 
artery in the hand, lying to its inner side. But the nerve lies 
behind, as well as to the inner side, when both enter the hand. 
Branches. 
Anterior Ulnar Recurrent 
Posterior Ulnar Recurrent 
Interosseous 
Muscular. 
The anterior ulnar recurrent arises from the ulna just below 
its origin and passes upward to the front of the inner side of 
the elbow, where it inosculates with the anastomotica magna. 
The posterior ulnar recurrent rises just below the preceding 
and passes upward and backward to the internal condyle. It 
passes to the interval between the olecranon and internal con- 
dyle and communicates with the anastomotica magna and the 
inferior profunda. 
The interosseous is a large trunk which arises from the ulna 
just below the elbow and quickly forks into an anterior and pos- 
terior interosseous. THE VASCULAR SYSTEM. 
349 
The anterior interosseous descends on the front of the interos- 
seous membrane, between the flexor profundus digitorum and 
flexor longus pollicis muscles, to the pronator quadratus, pass- 
ing beneath which it perforates the interosseous membrane and 
appears on the back of the forearm to inosculate with the pos- 
terior interosseous artery. It supplies the muscles in its route 
and gives off a companion branch to the median nerve. It com- 
municates with the posterior carpal arch and the posterior in- 
terosseous. 
The posterior interosseous, as soon as it is produced, passes 
between the bones above the interosseous membrane, to reach the 
back of the forarm and decend on the back of the forearm, be- 
tween the superficial and deep layer of muscles, to the wrist. 
Just as it reaches the back of the forearm it gives off a large 
branch, called the posterior interosseous recurrent, which 
ascends to the back of the elbow and communicates with the 
anastomotica magna. The posterior interosseous artery is dis- 
tributed to adjacent muscles. 
The muscular branches of the ulnar artery are numerous 
twigs to muscles in its course. 
Branches at the Wrist. 
Anterior Carpal 
Posterior Carpal 
The anterior carpal is a branch which passes outward on the 
front of the wrist to inosculate with the anterior carpal of the 
radial. From this arch branches pass to the carpal articulations. 
The posterior carpal passes backward and then runs outward 
on the back of the wrist to anastomose with the posterior carpal 
of the radial. From this arch are given off branches which sup- 
ply the ulnar side of the back of the little finger and interosseous 
branches to the next two spaces. These branches receive the 
posterior and anterior perforating arteries. 
These branches are very small and the anterior is frequently 
absent. 350 
DESCRIPTIVE ANATOMY. 
Branches in the Hand. 
Communicating 
Digital. 
The communicating branch dips between the abductor minimi 
digiti and flexor brevis minimi digiti to join the termination 
of the radial, completing the deep palmar arch. 
The thumb and each of the fingers have two palmar arteries,, 
one on either side, and two dorsal, similarly arranged, running 
from base to tip, called respectively palmar and dorsal collateral 
digital arteries. The digital arteries now under consideration are 
four in number, from the superficial palmar arch. The first is a 
small branch which supplies the inner side of the little finger; 
the second supplies adjacent sides of the little and ring fingers, 
splitting at the cleft between the two; the third does the same 
for adjacent sides of the middle and ring fingers and the fourth 
for adjacent sides of the middle and index fingers. 
These branches run along either side of the fingers until 
they reach the tip ; where, after giving off small branches which 
run beneath the nail and communicate with the dorsal arteries 
they inosculate with one another, completing the loop between 
the palmar arch and the digital arteries. 
Radial Artery of Wrist and Hand. 
When the radial artery reaches the wrist it turns outward, 
backward and downward beneath the extensor tendons of the 
thumb, viz: the extensor ossis metacarpi pollicis, extensor primi 
and extensor secundi internodii pollicis, in the order named, and 
passing through what is known as the snuff box-the sunken 
interval between the extensor ossis metarcarpi pollicis and ex- 
tensor primi internodii pollicis on one side and the extensor 
secundi internodii pollicis on the other-reaches the back of the 
hand where its appearance is only momentary, for it immedi- 
ately dips into the palm of the hand by passing between the two 
heads of the first dorsal interosseous muscle, and passing across 
the palm of the hand from the outer to the inner side, terminates 
by anastomosing with the communicating branch from the su- THE VASCULAR SYSTEM. 
351 
perficial palmar arch. The position of the radial in the palm, 
is deep, lying on the bases of the metacarpal bones and beneath 
the flexor tendons which separate it from the superficial palmar 
arch. It is called the deep palmar arch and is situated about 
half an inch nearer the wrist than the superficial arch. 
Branches of the Forearm. 
Recurrent Radial 
Muscular. 
The recurrent radial arises from the radial just below the 
elbow and passes upward and outward to the outer side of the 
front of the joint, where it lies in the space between the supina- 
tor longus and the brachialis anticus. It here inosculates with 
the anterior branch of the superior profunda. 
The muscular branches are numerous twigs to muscles in the 
course of the artery. 
Branches at the Wrist. 
Superficialis Volae 
Dorsalis Pollicis 
Anterior Carpal 
Metacarpea 
Posterior Carpal 
Dorsalis Indicis 
Princeps Pollicis. 
The super ficialis volae leaves the radial just as it turns out- 
ward, and passes to the muscles of the thenar group, usually 
perforating the abductor pollicis. Sometimes it anastomoses 
with the termination of the ulna, completing the superficial 
arch. 
The anterior carpal branch passes inward on the front of the 
joint to form the anterior carpal arch by uniting with the 
anterior carpal of the ulnar artery. 
The posterior carpal passes inward across the back of the 
wrist to inosculate with the posterior carpal of the ulna and 
form the posterior carpal arch. From the posterior carpal arch 
there pass down on the dorsal interosseous muscles two branches 
called posterior interosseous beside another which runs along DESCRIPTIVE ANATOMY. 
352 
the dorsal aspect of the ulnar border of the hand to supply the 
ulnar side of the dorsal aspect of the little finger. The posterior 
interosseous pass downward to divide the one at the cleft be- 
tween the little and ring fingers to form dorsal collateral digital 
branches for the adjacent sides of those fingers, while the other 
performs a similar duty for the adjacent sides of the ring and 
middle fingers. 
Just as the radial is passing the root of the thumb it gives off 
two small branches which course along the sides of the dorsal 
aspect of the thumb. They are called dorsales pollicis. 
The metacarpea is a branch which descends on the second 
dorsal interosseous muscle to the cleft between the middle and 
index fingers and there divides to form dorsal collateral digital 
branches for those fingers. 
The dorsalis indicis is a small branch which passes forward 
to form the dorsal collateral digital branch for the outer side 
of the index fingers. 
The princeps pollicis arises just as the radial dips into the 
palm of the hand and passes forward and outward to divide 
and form collateral digital arteries for the palmar aspect of 
the thumb. 
Branches of the Deep Palmar Arch (Arcus Volaris Profundus). 
Radialis Indicis 
Anterior Interosseous 
Perforating 
Recurrent. 
The radialis indicis, coming off close to the princeps pollicis, 
runs along the radial border of the index finger to its extremity 
and there anastomoses with the collateral digital artery of the 
superficial palmar arch. It also anastomoses with the princeps 
pollicis and gives a communicating branch to the superficial 
palmar arch, thus completing the arch, though sometimes the 
superficial arch is completed by anastomosing with the super- 
ficialis volse. 
The anterior interosseous are three or four small branches 
which pass forward on the front of the interosseous muscles 
to unite with the digital branches of the superficial arch. THE VASCULAR SYSTEM. 
353 
Besides these the deep arch gives off two sets of branches 
called perforating and recurrent. 
The recurrent are small branches, which pass upward from 
the deep arch to anastomose with the anterior carpal arch and 
supply the carpal articulations. 
The perforating arteries are three in number; passing back- 
ward between the heads of the last three dorsal interosseous 
muscles they inosculate with the dorsal interosseous arteries. 
The Aorta. 
The aorta commences at the base of the arterial ventricle, 
and terminates by dividing into the common iliac arteries on 
the front of the body of the fourth lumbar vertebra slightly to 
the left of the mid-line. It lies first in the thoracic, then in 
the abdominal cavity. Its direction is first upward, forward, 
and to the right; then backward, and to the left; and finally it 
turns downward until it reaches its point of bifurcation. It is 
divided for description into the ascending aorta, the transverse 
aorta, and the descending aorta, the latter being subdivided into 
the thoracic and abdominal portion of the descending aorta. 
The old subdivisions of ascending, transverse, and descending 
portions of the arch have been abandoned. 
The Ascending Aorta. 
The ascending AORTA begins at the base of the arterial ven- 
tricle at a point behind the left edge of the sternum, opposite 
the lower border of the third costal cartilage on a plane pos- 
terior to the pulmonary artery and anterior to the left auriculo- 
ventricular opening. It is about two inches in length, is di- 
rected upward, forward, and to the right, presenting a slight 
curve, whose convexity is to the right. Behind the upper border 
of the second costal cartilage of the right side it terminates by 
becoming the transverse aorta. Just above its origin it is some- 
what triangular on cross-section when distended, and presents 
three bulging prominences, which correspond to the sinuses of 
Valsalva. It lies in the fibrous pericardium, about one-fourth 354 
DESCRIPTIVE ANATOMY. 
of an inch behind the sternum; and is contained in the same 
fold of serous pericardium as the pulmonary artery. 
Relations. On its anterior aspect, at its origin, lies the pul- 
monary artery; but this vessel quickly winds to the left of the 
aorta, owing partly to the inclination of the aorta to the right, 
and partly to the oblique course of the pulmonary artery to 
the left. Above the pulmonary the aorta is separated from the 
sternum by the pericardium, some loose connective tissue, and 
the remains of the thymus gland, should any exist. It is slightly 
overlapped by the lung and pleura. At its origin it is over- 
lapped in front by the right auricular appendix; behind it lies 
the right pulmonary artery and other structures which enter 
into the formation of the root of the right lung and the left 
auricle of the heart. To its right at its base is the right auricle; 
and above this the superior vena cava. To the left, as already 
seen, is the pulmonary artery. 
The Transverse Aorta. 
The transverse aorta begins by being a continuation of the 
ascending aorta opposite the upper border of the second right 
costal cartilage; and with a gentle curve in its course, passes 
from right to left from before backward, and slightly from 
above downward, to terminate at the left side and lower border 
of the fourth dorsal vertebra, by becoming the descending aorta. 
The top of this arch is about an inch below the top of the ster- 
num ; and from it arise three large branches; the arteria innomi- 
nata, the left common carotid, and the left subclavian. 
Relations. In front it is overlapped very slightly by the right 
pleura, and to a much greater extent by the left pleura and 
lung, though the two pleurae do not come in contact. It is 
crossed in the order from left to right by the left phrenic, the 
cardiac branches of the pneumogastric, the left pneumogastric, 
and the left recurrent laryngeal nerves. The left superior in- 
tercostal vein also crosses the front of the transverse aorta. Be- 
hind, it rests upon the trachea, behind that is the oesophagus, 
and in the interval between the two the thoracic duct and the 
left recurrent laryngeal nerve. Above, it is in relation with its THE VASCULAR SYSTEM. 
355 
three branches in the order before mentioned, from right to 
left, and from before backward, the arteria innominata, left 
common carotid, and left subclavian; while above and towards 
its front aspect is found the great transverse vein of the neck, 
or the left innominate vein. Below it are the bifurcation of 
the pulmonary artery, the left bronchus, and the left recurrent 
laryngeal nerve, while it is connected by means of the ductus 
arteriosus with the pulmonary artery. The portion formerly 
described as "the descending portion of the arch of the aorta" 
will be considered with the thoracic aorta. 
Branches of the Ascending Aorta. 
Coronary Arteries. 
The right and left coronary branches arise from the 
ascending aorta. These branches arise from the corresponding- 
sinuses of Valsalva, the right arising from the right anterior 
sinus, and the left from the left anterior sinus. They descend 
into the anterior and posterior inter-ventricular furrows, and 
meet at the apex of the heart. Here they inosculate with one 
another, while each sends off a branch to supply the auriculo- 
ventricular grooves, anastomosing with one another and form- 
ing two vascular circles at right angles with one another, which 
completely surround the heart. 
Branches of the Transverse Aorta. 
Arteria Innominata 
Left Subclavian. 
Left Common Carotid 
The branches which spring from the transverse aorta are 
three in number, and bear a definite relation to one another; 
that is, the first, the arteria innominata, arises near the com- 
mencement of the transverse aorta; the left common carotid at 
the middle of the transverse aorta; and the left subclavian near 
the termination of the transverse aorta. 356 
DESCRIPTIVE ANATOMY. 
Arteria Innominata. 
The arteria innominata is the first and doubly the largest 
branch of the aorta. It arises from the beginning of the trans- 
verse aorta, passes upward and to the right for a little less than 
two inches to terminate behind the upper border of the right 
sterno-clavicular articulation by dividing into the right common 
carotid and right subclavian arteries. In other words, in it are 
blended the right common carotid and right subclavian vessels. 
Relations. In front is the sternum, from which it is sepa- 
rated by some loose connective tissue, by the prolongation of 
the fibres of origin of the sterno-hyoid and sterno-thyroid mus- 
cles, and by the remains of the thymus gland, should there be 
any. Across the front of it, just at its origin, passes the left 
innominate vein, or great transverse vein of the neck, and the 
right inferior thyroid vein and the inferior cervical cardiac 
branch of the pneumogastric. It is overlapped by the right 
pleura and lung. Behind, at its commencement, it rests upon 
the trachea; but the obliquity of the artery soon carries it to 
the right of the trachea, which then becomes a left or internal 
relation to the arteria innominata. On the right side is the right 
innominate vein, the right pleura, and the right pneumogastric 
and phrenic nerves, which are rather distant relations. On the 
left at its commencement is the left common carotid artery, 
which lies to the left and on a plane slightly posterior, sepa- 
rated from the arteria innominata by a triangular interval in 
which the trachea may be seen. Higher up is the trachea. It 
usually produces no branches except its terminal branches. The 
remains of the thymus and the left inferior thyroid vein are 
also relations on its left. 
Left Common Carotid. 
The left common carotid, the second branch arising from 
the transverse aorta, occupies a position midway between the 
innominate and left subclavian arteries. 
Relations. Its relations in the thorax are somewhat similar 
to those of the arteria innominata, but not identical with them. THE VASCULAR SYSTEM. 
357 
After passing above the left sterno-clavicular articulation, its 
relations become identical with those of the right common caro- 
tid, and a description of one answers for the other. It springs 
from the highest portion of the transverse aorta, lying with the 
innominate to its right and on a plane slightly anterior, the left 
subclavian to its left and on a plane slightly posterior. It is 
separated from the sternum by the origin of the sterno-thyroid 
and sterno-hyoid muscles of the left side, some loose connective 
tissue, and the remains of the thymus gland; and is crossed in 
front by the great transverse vein, though at a higher level 
than that at which the same vein crosses the innominate artery. 
It is overlapped in front by the left lung and pleura. Behind 
it, at its origin, lies the trachea, which is behind and slightly 
to its inner side. Crossing obliquely behind is the left recur- 
rent laryngeal nerve, while behind and to its outer side is 
seen the thoracic duct. As it ascends, the trachea becomes an 
internal relation, and the oesophagus a postero-internal rela- 
tion, the recurrent larngeal nerve lying in the groove between 
these two structures. To its inner side at its commencement is 
the innominate artery; and above this, and internal and pos- 
terior to it, the trachea. To its inner side is also the inferior 
thyroid vein. To its outer side is the left subclavian, which is 
external and slightly posterior; while in the interval between 
the subclavian and the carotid are seen the pneumogastric and 
phrenic nerves, external relations of the carotid. 
The Left Subclavian. 
The left SUBCLAVIAN arises from the termination of the trans- 
verse aorta. It passes upward and to the left; and its first 
or thoracic portion terminates at the inner edge of the scalenus 
anticus muscle by becoming the second portion of the artery. 
From this point to its termination, the left subclavian is identi- 
cal with the right. 
Relations. The left subclavian is almost enveloped by the 
left pleura, which covers it in front, to the outer side, and be- 
hind. It has the left common carotid lying internal to it and 
slightly in front of it, while more superficially are the origins DESCRIPTIVE ANATOMY. 
358 
of the sterno-hyoid and sterno-thyroid muscles, and the re- 
mains of the thymus gland, should there be any. Near its 
origin, but higher than at the point of crossing of the left com- 
mon carotid, is found the great transverse vein of the neck, 
while near the termination of the first portion the internal jugu- 
lar and the subclavian veins of the left side unite to form the 
innominate on the front of the subclavian artery. The left 
vertebral and first intercostal veins are also anterior relations. 
The phrenic nerve crosses it near the scalenus anticus muscle, 
and then passes downward, parallel to the pneumogastric, but 
external to, and in front of, that nerve. The pneumogastric 
itself lies in the interval between the subclavian and the left 
common carotid on a plane anterior to both, but internal to 
the subclavian, while external to the carotid. Below it, as well 
as to its outer side, are the pleura and the left lung. The trachea, 
oesophagus, and recurrent laryngeal nerve might be considered 
distant internal relations. The relation of the thoracic duct 
should be carefully noted. It ascends nearly opposite the in- 
terval between the left common carotid and the subclavian, 
passes above the point at which the subclavian arches outward 
toward the scalenus anticus muscle, then turns to the front 
of the artery to empty into the junction of the internal jugular 
and subclavian veins, so that its relationship to the artery is a 
three-fold one: being first behind it, then above it, then in front 
of it, at its termination. 
The Descending Aorta. 
The DESCENDING aorta commences by being a continuation of 
the transverse aorta at the left side and lower border of the 
body of the fourth dorsal vertebra, and terminates opposite the 
body of the fourth lumbar vertebra by dividing into the two 
common iliacs. It consists of the thoracic and abdominal por- 
tions. 
The Thoracic Aorta. 
The THORACIC PORTION of the descending aorta, commencing 
at the fourth dorsal vertebra, terminates opposite the body of THE VASCULAR SYSTEM. 
359 
the twelfth dorsal, slightly to the left of the mid-line, by be- 
coming the abdominal aorta. The course of the thoracic aorta 
is downward, with a slight inclination to the right, so that from 
lying first upon the lateral aspect of the body of the fifth dorsal, 
it changes its relative position to the bodies of the vertebrae to 
such a degree that at its point of termination it is on the front 
of the bodies, and but slightly to the left of the mid-line. It pre- 
sents a curve in its course slightly concave in front to corre- 
spond with the dorsal curvature of the spinal column upon which 
it rests. 
Relations. This vessel is covered throughout its course by 
the pleura; and lies with other important structures in the pos- 
terior mediastinum. In front, opposite the body of the fifth 
dorsal vertebra, is the root of the left lung, consisting mainly 
of the pulmonary artery, the pulmonary veins, the left bronchus, 
lymphatics, nerves, and small blood vessels. Below this it lies 
behind the pericardium; and is completely covered over by the 
left pleura and lung. Important relations are borne to it by 
the oesophagus, thoracic duct, and pneumogastric nerves. The 
two pneumogastric nerves course downward, the left upon the 
front and the right upon the back of the oesophagus, and hence 
bear the same relation to the aorta that this structure does. 
Owing to the changes in the direction of the oesophagus as well 
as to the obliquity of the aorta, the oesophagus above lies to the 
right of the descending aorta. About the middle of the course 
of the artery it is directly in front of it, while opposite the tenth 
dorsal vertebra, where the oesophagus terminates, it is still fur- 
ther in front and to the left of the aorta. The thoracic duct is 
continuously behind and slightly to the right of the aorta, lying 
usually in the interval between the aorta and the great azygos 
vein. To the right of the aorta is the great azygos vein, opening 
into which opposite the sixth dorsal vertebra is the left azygos, 
which crosses behind the aorta. The extent to which the aorta 
is covered by the pleura decreases as it descends. In the upper 
portion of its course, all of the vessel except a small part of its 
right side, which rests upon the bodies of the vertebrae, is en- 
veloped by the pleura, while near its termination the pleura 
covers only its outer aspect. DESCRIPTIVE ANATOMY. 
360 
Branches. 
Bronchial 
Intercostal 
Mediastinal 
Pericardiac 
(Esophageal. 
The branches of the thoracic descending aorta are small, al- 
though there are a large number of them. 
The bronchial arteries, usually three to the left and one to 
the right lung, course along the bronchi to the lungs, and ramify 
with the bronchial tubes. These vessels, it should be under- 
stood, have no connection with the pulmonary artery; but simply 
furnish a nutrient supply for the lung tissue itself. Their 
method of distribution belongs to the domain of histology. 
The oesophageal axe a number of small twigs, four or five, 
which are successively furnished to the oesophagus as that tube 
comes into relationship with the thoracic aorta, and which com- 
municate with one another and with other oesophageal arteries. 
The mediastinal and pericardiac are small twigs furnished 
to the posterior mediastinum and to the pericardium respec- 
tively. 
The intercostal, the largest and most numerous of the 
branches, are ten pairs, which rise from both sides of the thoracic 
aorta, and run out into the intercostal spaces, except the upper 
space, which is supplied by the superior intercostal of the sub- 
clavian, and the space below the last rib, or sub-costal space, 
which is supplied by one of the terminal branches of the internal 
mammary. The right intercostal arteries are, of course, longer 
than the left from having to cross the vertebral column. Each 
intercostal artery passes outward in its corresponding space to 
run along the lower border of the rib above in the groove which 
is formed for lodging the artery and the nerve; and after going 
some distance, gives off a branch, which descends to course 
along the upper border of the rib below. The arteries of the 
right side pass behind the vena azygos major and thoracic duct. 
Further out they pass behind the sympathetic system; and lie 
first upon the internal intercostal muscle, and then, at the angle 
of the rib, between the two intercosal muscles. They continue THE VASCULAR SYSTEM. 
361 
their course to finally inosculate with the intercostal branches 
from the internal mammary for the upper spaces, and those 
from the musculo-phrenic for the lower spaces. Before termi- 
nating each intercostal gives off a dorsal branch, whose distri- 
bution corresponds to the dorsal nerves; that is, it divides into a 
muscular and a spinal branch, the spinal to enter the spinal 
canal, and the muscular to be distributed to the deep muscles 
of the back. 
The Abdominal Aorta. 
The abdominal aorta commences on the body of the twelfth 
dorsal vertebra, slightly to the left of the mid-line, being a con- 
tinuation of the thoracic aorta. It passes behind the diaphragm, 
through the aortic opening, and curves backward and to the 
left, the convexity being to the left. About the middle of its 
course it changes its direction and curves slightly to the right, 
so that it finally terminates on the body of the fourth lumbar 
vertebra, usually to the left of the mid-line, by dividing into the 
two common, or primitive, iliac arteries. This position is indi- 
cated by a line drawn from the highest point of the crest of 
the ilium of one side to the same point of the opposite side, or 
by a point selected half-an-inch below and to the left of the um- 
bilicus. In addition to the curvature to the left, it also is 
slightly convex forward, conforming to the lumbar portion of 
the spine. Owing to the large size and great number of the 
branches given off, it is greatly reduced in size at its termination. 
Relations. Posteriorly this artery rests upon the front of the 
bodies of the lumbar vertebrae; but at several points it is sepa- 
rated from these vertebrae by intervening structures. Opposite 
the second lumbar vertebra is the commencement of the thoracic 
duct, the receptaculum chyli; and throughout its course are 
found, passing behind it, the left lumbar veins, opposite the cor- 
responding vertebrae, as they make for their points of entrance 
into the inferior vena cava. Above, to the left, are the left crus 
of the diaphragm and a portion of the sympathetic system, the 
left semilunar ganglion; to the right, the right crus of the diaph- 
ragm and a portion of the sympathetic, the right semilunar 
ganglion, and the right vena azygos, while throughout the course 362 
DESCRIPTIVE ANATOMY. 
of the vessel the inferior vena cava lies upon its right. In 
front is the stomach. Opposite the upper border of the stomach 
one of the largest branches of the abdominal aorta arises, the 
coeliac axis; and this is surrounded by cords of the sympathetic 
system, forming the solar plexus of nerves with its two semilu- 
nar ganglia. These ganglia are found lying to the front and 
lateral aspects of the commencement of the abdominal aorta. 
Below this comes the head of the pancreas, and immediately be- 
low this the left renal vein, the transverse portion of the duode- 
num, and the mesentery. Below this the aorta is covered at the 
front and at the sides by the peritoneum and the aortic plexus of 
sympathetic nerves. Another of its branches, the superior 
mesenteric, lies for a short distance in front of it; but curves 
to the right to become a distant relation of the artery. The in- 
ferior mesenteric branch is a momentary anterior relation, but 
soon drops to the left. Convolutions of the small intestines 
cross over the front of the vessel, and are separated from it by 
the peritoneum, which covers it throughout, the aorta lying be- 
hind the peritoneum. 
Branches. 
Phrenic 
Parietal 
Sacra Media 
Lumbar 
Coeliac Axis 
Visceral 
Superior Mesenteric 
Inferior Mesenteric 
Spermatic or ovarian 
Genito-Urinary 
Renal 
Supra-renal 
The branches of the abdominal aorta, nine in number, are 
arranged in three sets: those distributed to the abdominal wall, 
the parietal branches; those to the abdominal viscera, the or- 
gans of digestion, and those accessory thereto; and those dis- 
tributed to the genito-urinary organs. THE VASCULAR SYSTEM. 
363 
The Parietal Branches. 
Phrenic 
Sacra Media 
Lumbar 
Phrenic. 
The phrenic are a pair of small arteries, arising from the 
aorta soon after it enters the abdomen. Their manner of origin 
is variable. They may arise by a common trunk; they may arise 
separately from the aorta; or, in some cases, one will arise from 
the aorta and the other from one of the adjacent arteries, most 
frequently the renal. Each artery runs upward and outward 
on the under surface of the diaphragm. Below the oesophageal 
opening each divides into two branches, one of which encircles 
this opening anastomosing with its fellow of the opposite side, 
and furnishing the arterial supply for a large part of the cen- 
tral tendon of the diaphragm. The other and larger branch 
passes outward on the concave under surface of the muscle, 
supplies the muscular fibre, and inosculates with the musculo- 
phrenic branch of the internal mammary and with the other 
diaphragmatic arteries. 
Lumbar. 
The lumbar arteries are four or five pairs of small branches, 
which spring successively from the back of the aorta, and run 
outward to ramify in the broad muscles of the abdomen. These 
vessels pass beneath the musculo-tendinous arches formed by 
the tendinous fibres of the psoas magnus and the concave lateral 
aspect of the bodies of the lumbar vertebrae. 
They resemble in direction and in distribution the intercostal 
arteries. Passing in this way beneath the psoas magnus, these 
vessels divide into an anterior branch, which corresponds to 
the intercostal artery, and a posterior branch, which corres- 
ponds to the dorsal division of the intercostal. These posterior 
divisions supply the small arteries of the bodies of the vertebrae, 
and, continuing their course, give off the spinal branches to the 
contents of the spinal canal, while the remaining portion is dis- 364 
DESCRIPTIVE ANATOMY. 
tributed to the muscles of the back. The larger anterior divi- 
sion passes forward in the broad muscles of the abdomen, 
inosculates with other vessels which supply those muscles, mainly 
for the upper branches, with the terminal branches of the in- 
ternal mammary, and for the lower lumbars with the branches 
which spring from the deep epigastric and ilio-lumbar. 
Sacra Media. 
The SACRA media is a somewhat slender branch, which arises 
just at the bifurcation of the aorta, though occasionally from 
one of its forks. It passes down upon the front of the sacrum, 
gives off branches which anastomose with the lateral sacral ar- 
teries, and continues its course to the tip of the coccyx, ter- 
minating in the vascular gland found in that situation, which 
is known as Luschka's, or the coccygeal, gland. 
The Visceral Branches. 
Cceliac Axis. 
Superior Mesenteric. 
Inferior Mesenteric. 
The visceral branches spring from the abdominal aorta by 
three' trunks, the coeliac axis and the superior and inferior 
mesenteric. 
The Cceliac Axis. 
The cceliac axis is the first and largest of these trunks. 
It is about half an inch in length. It arises from the front 
of the abdominal aorta, near its commencement, and passes 
directly forward to break up into three terminal branches, the 
gastric, the splenic, and the hepatic. 
Relations. The artery arises just above the head of the pan- 
creas, upon which it rests. In front of it is the lesser omen- 
tum, and to the right is the lobus Spigelii, while the cords of the 
solar plexus surround the artery in every aspect, and a semi- 
lunar ganglion lies upon either side. Its position corresponds 
to the level of the upper border of the stomach, while imme- 
diately below it and almost in contact with it is the origin of THE VASCULAR SYSTEM. 
365 
the next branch, the superior mesenteric. On the left side it 
is relation with the cardiac end of the stomach. 
Branches. 
Gastric. 
Splenic. 
Hepatic. 
Gastric. 
The gastric is the smallest branch arising from the coeliac 
axis. It passes upward and to the left until it reaches the 
cardiac end of the stomach, where it turns to the right, runs 
along the lesser curvature between the two layers of the lesser 
omentum nearly to the pylorus, where it inosculates with the 
pyloric branch of the hepatic artery. Just before making its 
turn to the right it gives off branches to the large end of the 
stomach; and in coursing along the upper border it gives 
branches which pass downward to both the anterior and pos- 
terior faces of that organ. 
The Splenic Artery. 
The splenic ARTERY is the largest of the branches arising 
from the coeliac axis. It is very tortuous, runs directly from 
right to left along the upper border of the pancreas to reach 
the hilum of the spleen, where it splits into numerous branches 
to be distributed to that organ. As it courses along the pancreas, 
it lies behind the stomach and just above the splenic vein, which 
lies on the posterior surface of the pancreas in a groove a 
little distance below the artery. 
Before reaching the spleen, the artery gives off a number 
(five or six) of large branches, which pass to the splenic end 
of the stomach, and, under the name of the vasa brevia, inoscu- 
late with the branches of the gastric artery, and supply the 
cardiac or splenic end of the stomach. 
As it passes along the upper border of the pancreas, numerous 
small pancreatic branches are given off, which descend into that 366 
DESCRIPTIVE ANATOMY. 
gland. One of them, of larger size, is frequently individualized 
as the pancreatica magno). 
One of its terminal branches, the gastro-epiploica sinistra, 
leaves the artery near the spleen, runs to the right along the 
greater curvature of the stomach between the layers of the great 
omentum, and about the middle of the greater curvature of the 
stomach inosculates with the gastro-epiploica dextra, an in- 
direct branch of the hepatic artery. From this artery, the 
gastro-epiploica sinistra, branches ascend to both faces of the 
stomach, and descend to supply the great omentum. 
The Hepatic Artery. 
The hepatic is intermediate in size between the gastric and 
the splenic. Its usual course is to pass to the right and slightly 
upward, then make an abrupt bend and pass nearly vertically 
upward to the under surface of the liver, where it divides into 
two branches, one to each lobe of the liver, hence known as 
the right and left hepatic arteries. This artery is accompanied 
by a duct and a vein. The three structures are in close contact, 
the duct lying furthest to the right and the artery to the left, 
while opposite the interval between them, and on a plane pos- 
terior to both, is found the portal vein, this vein being formed 
by the junction of the superior mesenteric with the splenic. 
The usual manner of expressing the description is: duct to the 
right, artery to the left, vein between and behind the two. 
The terminal branches of the artery ramify in the liver, and 
furnish the arterial blood for nourishing that organ. 
Besides these branches it produces the pyloric, which arises 
near the bend in the hepatic, passes to the left along the lesser 
curvature of the stomach until it meets the gastric artery, 
inosculates with that vessel, and, like it, is distributed to both 
faces of the stomach. 
The next branch, generally called the gastro-duodenalis, and 
described as divided into the pancreatico-duodenalis superior 
and the gastro-epiploica dextra, is preferably described as the 
gastro-epiploica dextra. This artery arising from the hepatic, 
where it turns upward to the liver, passes behind the pylorus THE VASCULAR SYSTEM. 
367 
and follows the greater curvature of the stomach, giving off 
as a way-side branch, the pancreatico-duodenalis superior. This 
small branch descends to the interval between the duodenum 
and the head of the pancreas, and is distributed to both of 
these structures and anastomoses with the pancreatico-duo- 
denalis inferior, a branch of the superior mesenteric; the parent 
trunk continues between the folds of the great omentum until 
it inosculates with the gastro-epiploica sinistra, forming the loop 
from which ascending branches pass to both faces of the 
stomach and descending branches pass to supply the great 
omentum. 
The right branch of the hepatic artery likewise gives off a 
branch, called the cystic, which passes to the gall bladder and 
divides into two branches, running between the gall bladder 
and the under surface of the liver, is distributed to the gall 
bladder and duct, the other ramifies on the free surface of the 
gall bladder. This branch is sometimes described as a third 
terminal branch of the hepatic artery. 
It will be seen, therefore, that the branches of the coeliac 
axis freely anastomose with one another, the splenic anastomos- 
ing with the gastric at the left of the stomach, and with the 
hepatic, through the gastro-epiploica dextra, at the middle of 
the greater curvature. The hepatic anastomoses by its pyloric 
branch with the gastric on the upper curvature, and with the 
splenic on the lower curvature. 
Superior Mesenteric. 
The SUPERIOR mesenteric is a large vessel, which arises from 
the front of the aorta just below the coeliac axis and behind the 
head of the pancreas. Between it and the coeliac axis are some 
branches of the solar plexus of nerves. It descends between 
the lower border of the pancreas and the transverse duodenum 
and passes to the right iliac fossa, presenting in its course a 
curve, whose convexity is to the left, lying between the layers 
of the mesentery. 
Relations. At its origin this vessel lies behind the head of the 
pancreas. It then descends for about an inch and a half, the 368 
DESCRIPTIVE ANATOMY. 
width of the pancreas, covered by that structure. It appears 
in the interval between the lower border of the pancreas and 
the transverse duodenum; then crosses in front of the trans- 
verse duodenum; and from that point onward continues in the 
fold of the mesentery, moving with the mesentery in the ab- 
dominal cavity. It is accompanied throughout by the superior 
mesenteric vein. 
Branches. 
Pancreatico-Duodenalis Inferior. 
Colica Dextra. 
Vasa Intestini Tenuis. 
Colica Media. 
Ileo-Colic. 
Soon after its origin the superior mesenteric artery gives 
off a small branch, called the pancreatico-duodenalis inferior, 
which passing upward between the pancreas and the duodenum, 
anastomoses with the pancreatico-duodenalis superior, and aids 
it in supplying the descending duodenum and the head of the 
pancreas. The remaining branches are divided into two sets, 
those which spring from the concave and those which spring 
from the convex aspect of the vessel. The convexity of this 
vessel looks downward, to the left, and slightly forward; the 
concavity looks upward, to the right, and slightly backward. 
Vasa Intestini Tenuis. 
From the convex face arise a number of branches, varying 
from ten to eighteen in number, the vasa intestini tenuis. 
These branches inosculate so freely with one another that the 
the circulation in the intestinal wall is still abundantly supplied 
though a large number of the branches may be ligated. They 
decrease in size from above downward; and their distribution 
is not quite regular, though the plan of distribution is always 
the same. Thus each branch in passing outward divides into 
an ascending and a descending branch. These branches inos- 
culate with the corresponding branches above and below so as 
to form a series of arches. From these arches are given off a 
second set of branches, which, likewise, divide into two, and THE VASCULAR SYSTEM. 
369 
inosculate with those above and below, forming a second series 
of arches. This second series, in like manner, forms a third; 
and in some cases as many as five or six series of arches may 
be discovered. As a rule, the number of arches does not ex- 
ceed three; and in some few cases only two may be discovered. 
No matter what the number of arches, from the terminal arch 
there proceeds a set of straight vessels, the rasa recta, which 
pass outward on both faces of the small intestine, completely 
encircling the gut and inosculate with each other, so that both 
in its circumference and in its vertical measurement the anas- 
tomoses between the vertical arches of the small intestine are 
free and uninterrupted. 
From the concave side of the vessel there are three branches. 
In the order in which they arise from below upward they are 
named the ileo-colic, the Colica dextra, and the colica media. 
It is sometimes seen that there is no distinct ileo-colic artery; 
but that its place is taken by the termination of the superior 
mesenteric itself. As a general rule, however, the superior 
mesenteric terminates by becoming the last of the vasa in- 
testini tenuis; and the ileo-colic is given off from the concave 
aspect of the vessel. 
Ileo-Colic. 
The ILEO-COLIC, the first of the three branches to arise from 
the concave aspect, is distributed somewhat after the manner 
of the vasa intestini tenuis; but with larger arches, or rather 
with loops instead of arches. Passing downward and outward 
toward the right iliac fossa, it divides into an ascending and 
a descending branch. The descending branch passes back to 
inosculate with the vasa intestini tenuis or with the termination 
of the superior mesenteric. The ascending branch passes up- 
ward to reach the descending branch of the colica dextra, thus 
forming two large loops, from which the straight branches are 
given off to supply the termination of the small intestine and 
the beginning of the large intestine. 370 
descriptive anatomy. 
Colica Dextra. 
The colica dextra, in like manner, passing straight out- 
ward, divides into an ascending and a descending branch, the 
descending to anastomose with the ascending branch of the 
ileo-colic, and the ascending with the descending branch of the 
colica media. 
Colica Media. 
The COLICA media, the highest of the three branches, passes 
downward and to the right, with the intestine in the anatomical 
position, and divides into an ascending and a descending, or, 
more accurately, right and left branches, the descending, or 
right, branch to anastomose with the ascending branch of 
colica dextra; the ascending, or left branch to inosculate with 
the colica sinistra; which is a branch of the inferior mesenteric. 
From the loops formed by these three vessels are supplied 
the termination of the small intestine, the caecum, or beginning 
of the large intestine, the ascending colon, and the transverse 
colon to its middle, where the colica sinistra takes up the work. 
Inferior Mesenteric. 
The inferior mesenteric is much smaller than the superior. 
It arises from the front of the abdominal aorta near its ter- 
mination, and descends obliquely to the left iliac fossa, where 
it finally terminates by passing over the brim of the pelvis 
under the name of the superior hemorrhoidal artery, and be- 
coming a relation of the iliac vessels. 
Branches. 
Colica Sinistra. 
Sigmoid. 
Superior Hemorrhoidal. 
Colica Sinistra. 
The colica sinistra, the first and largest branch, passes to 
the left and divides into an ascending and a descending branch. THE VASCULAR SYSTEM. 
371 
The ascending branch inosculates with the left branch of the 
colica media, and the descending with one of the sigmoid 
branches of the inferior mesenteric. From these two loops are 
supplied the left end of the transverse colon and the descend- 
ing colon. 
Sigmoid Branches. 
The sigmoid are several branches, varying in number and in 
size, sometimes there being but a single branch, which passes 
outward to the sigmoid flexure of the colon, and divides as the 
colica sinistra does, the ascending branch inosculating with the 
colica sinistra, while the descending branch, or last branch 
where there are several, inosculates with the superior hemor- 
rhoidal or termination of the superior mesenteric itself. These 
branches supply the sigmoid flexure of the colon. 
Superior Hemorrhoidal. 
The superior hemorrhoidal descends along the posterior 
aspect of the rectum, lying between the two layers of peri- 
toneum which hold the rectum in position. It reaches the 
middle of the rectum, where it anastomoses with the other 
hemorrhoidal arteries; but before reaching this point it has 
received the anastomosis with the sigmoid branches of the 
inferior mesenteric. 
Summary. 
From the foregoing description it will be seen that the 
stomach is supplied with blood as follows: The lesser curvature 
by the loop formed between the gastric artery and the pyloric 
branch of the hepatic; the greater curvature by the right gastro- 
epiploica from the hepatic and the left gastro-epiploica from the 
splenic; the splenic end of the stomach by the vasa brevia from 
the splenic artery and by branches from the gastric. All of 
these branches communicate with one another so as to render 
the stomach a net-work of arterial branches. 
The duodenum is chiefly supplied by the pancreatico-duo- 
denalis superior of the hepatic, which vessel is aided in its work 372 
DESCRIPTIVE ANATOMY. 
by the pancreatico-duodenalis inferior from the superior mesen- 
teric, establishing a communication between the branches of 
the coeliac axis and the superior mesenteric artery. 
The small intestine from the duodenum to near the large in- 
testine is supplied by the vasa intestini tenuis of the superior 
mesenteric. The termination of the small, and the beginning of 
the large, intestine are supplied by the ileo-colic branch of the 
superior mesenteric, anastomosing with the termination of the 
superior mesenteric itself. 
The ascending colon is supplied by the loop between the colica 
dextra and the ileo-colic below, and the colica media above. 
The right half of the transverse colon is supplied by the loop 
between the colica media and the colica dextra, the left half 
by the loop between the colica media and the colica sinistra, thus 
establishing a communication between the superior and inferior 
mesenteric arteries. 
The sigmoid flexure is supplied by the sigmoid branches, after 
anastomosing with the colica sinistra, and by the superior 
hemorrhoidal branch of the inferior mesenteric, after anas- 
tomosing with the sigmoid branches. 
Thus, beginning with the first visceral branch of the ab- 
dominal aorta, we find that the three branches which supply all 
of the hollow viscera and many of the solid viscera of the 
abdomen not only communicate with the branches given off 
from each other, but communication is established between the 
three by the inosculation between the coeliac axis and the 
superior mesenteric and between the superior mesenteric and 
the inferior mesenteric. 
Genito-Urinary Branches. 
Spermatic (in the male) 
Renal. 
Ovarian (in the female). 
Supra-renal. 
Spermatic. 
The spermatic are a pair of small branches, which arise from 
the front of the aorta, and descend behind the peritoneum to THE VASCULAR SYSTEM. 
373 
the brim of the pelvis, one on either side. The left spermatic 
arises at a lower level, and is consequently a little shorter than 
the right. Each artery passes across the external iliac close 
to its termination, enters the deep abdominal ring, and travers- 
ing the inguinal canal, leaves the abdomen at the superficial ring 
to accompany the other elements of the cord to the testicles, 
where it is distributed. 
Ovarian. 
The ovarian artery arises like the spermatic, and its rela- 
tions are the same in the upper part of its course; but on reach- 
ing the brim of the pelvis it crosses the common iliac artery, 
passes into the folds of the broad ligament; then reversing its 
course, runs outward to be distributed to the ovary, a branch 
having been given to the uterus, to the laminae of the broad liga- 
ment, and to the Fallopian tube. Other branches continue along 
the round ligament, through the inguinal canal, to the integu- 
ment of the labia and groin. 
Suprarenal. 
The SUPRA-RENAL are a pair of small arteries, which arise 
from the aorta above the origin of the renal, and pass outward 
on either side to be distributed to the supra-renal capsule. These 
arteries frequently arise from the renal artery itself; and gen- 
erally there are two or three on either side of the body. 
Renal. 
The RENAL arteries are a pair of large vessels, which spring 
at right angles from the abdominal aorta, rising just below the 
superior mesenteric. They pass transversely outward, with 
the vein lying in front and the ureter behind them. On the 
right side the renal artery passes behind the vena cava. Just 
as they reach the hilum of the kidney they break up into, usu- 
ally, three branches, one of which frequently goes in front of 
the renal vein. They enter the hilum of the kidney to be distrib- 374 
DESCRIPTIVE ANATOMY. 
uted to that organ. The left renal is on a somewhat higher plane 
than the right, owing to the relative position of the kidneys. 
The Common, or Primitive, Iliac Arteries. 
The common, OR primitive, iliac artery of each side begins 
by being one of the terminal branches of the abdominal aorta, 
where that vessel terminates a little to the left of the middle 
of the body of the fourth lumbar vertebra, the exact point of 
division, however, varying slightly, sometimes as much as an 
inch. From this origin the artery passes downward and out- 
ward to the brim of the pelvis to terminate on the side of the 
disk between the fifth lumbar vertebra and the sacrum by divid- 
ing into the external and internal iliac arteries. The average 
length of each artery is about two inches; but the right is 
slightly longer than the left, owing to the division of the aorta 
to the left of the middle line of the body. 
Their relations are not identical. 
Right Common Iliac. 
Relations. The right common iliac, like the left, lies behind 
the peritoneum. It is usually crossed in front near its termina- 
tion by the right ureter, though this sometimes extends to the 
external iliac. Convolutions of the small intestine and the sym- 
pathetic nerves are also found in front of it. In the female it' 
is crossed by the ovarian artery in front. To its outer side 
is the psoas magnus muscle. Behind it is crossed by the left 
common iliac vein, which joins the right common iliac to the 
outer side of the beginning of the artery to form the inferior 
vena cava. Hence its relations to veins are quite complex, 
having at its commencement the junction of the two veins to 
its outer side and on a plane posterior to it, then its own vein 
external and behind, and then the left common iliac vein di- 
rectly behind it. It lies on the last lumbar vertebra. THE VASCULAR SYSTEM. 
375 
Left Common Iliac. 
Relations. The left common iliac is crossed in front by the 
sigmoid flexure of the colon, by the superior hemorrhoidal artery, 
and, near its termination, usually, by the left ureter. Ex- 
ternal to it is the psoas magnus muscle. Throughout its course 
its vein is behind and internal to it. It lies on the last lumbar 
vertebra. 
The common iliac arteries give off no branches. 
External Iliac. 
The external iliac, one of the two terminal branches of the 
common iliac, commences where that artery bifurcates on the 
disk between the fifth lumbar vertebra and the sacrum, into 
itself and the internal iliac. It continues the course of the 
parent artery downward and outward, and enters the thigh, 
to become the femoral artery, by passing beneath Poupart's 
ligament at a point midway between the anterior superior 
spinous process and the symphysis pubis. Its course and that 
of the common iliac may be indicated by drawing a line from a 
point just to the left of the umbilicus, the point of bifurcation 
of the abdominal aorta, to a point midway between the anterior 
superior spinous process of the ilium and the symphysis pubis. 
Relation. To the outer side of the artery is the psoas magnus 
muscle, separated from it by the iliac fascia, which throws a 
covering over the artery and vein. In front is the peritoneum, 
the sub-peritoneal fascia, and convolutions of the small intes- 
tine. The vermiform appendix often lies on the front of the 
artery, on the right, separated from it by the peritoneum, but 
usually,, runs over the inner side of artery and vein and may en- 
danger the latter. Near its termination the artery is crossed 
in front by the genital branch of the genito-crural nerve and 
by the spermatic artery. In the female, of course, there is no 
spermatic artery to cross. Sometimes it is crossed at its be- 
ginning by the ureter, though that structure usually crosses 
the termination of the common iliac. On the left the vein is 
throughout an internal relation to its artery, and on a plane 376 
DESCRIPTIVE ANATOMY. 
posterior to it until it reaches Poupart's ligament; on the right 
the vein is at first directly behind, where it unites with the 
internal iliac vein. Then it becomes internal, and at Poupart's 
ligament becomes fully abreast of the artery, so that on both 
sides at Poupart's ligament the vein is internal and abreast of 
the artery, while on the left side it remains internal and on a 
plane posterior throughout the remainder of its course; but on 
the right, when traced from below, it is first abreast, then in- 
ternal and on a plane posterior, and then directly behind. 
Branches. 
Deep Epigastric. 
Deep Circumflex Iliac. 
Deep Epigastric. 
The deep epigastric artery arises from the inner side of the 
external iliac near Poupart's ligament. It first runs upward 
and inward on the posterior face of the anterior abdominal wall 
beneath the peritoneum and the transversalis fascia, which it 
raises into a ridge. It then enters the sheath of the rectus 
muscle; passes upward, first between the sheath and the muscle, 
and then punctures the fibres of the muscle itself, to terminate 
by anastomosing with the epigastric branch of the internal 
mammary, thus establishing a communication between the ar- 
teries of the upper and the arteries of the lower extremity. 
Soon after its origin it gives off a communicating branch, which 
descends to the obturator artery; and, in many instances, takes 
the place of the obturator artery itself. The relations to the 
abdominal rings will be explained in connection with the ob- 
turator artery. In addition to the communicating branch to the 
obturator, it gives off a branch which accompanies the cremaster 
muscle, muscular branches to the rectus muscle itself, a pubic 
branch which passes to the back of the pubes to anastomose 
with its fellow of the opposite side, and cutaneous branches, 
which pierce the rectus to supply the skin covering that muscle. THE VASCULAR SYSTEM. 
377 
Deep Circumflex Iliac. 
The deep circumflex iliac, the second branch of the ex- 
ternal iliac, arises from the outer side of the external iliac just 
above Poupart's ligament, and a little higher up than the epi- 
gastric. It lies beneath the peritoneum; passes upward and out- 
ward parallel with and above Poupart's ligament until it reaches 
the crest of the ilium, where it usually divides into two branches, 
one of which passes upward and anastomoses with the ilio-lum- 
bar and intercostal arteries, the other continues along the crest 
of the ilium to anastomose with the gluteal and the lowest lum- 
bar artery. In its course it gives off muscular branches, which 
aid in supplying the broad muscles of the abdomen, and cutane- 
ous branches, which pierce to the skin and anastomose with 
other cutaneous branches. 
The Femoral Artery. 
The femoral artery is the continuation of the external iliac, 
commencing where that artery terminates, beneath Poupart's 
ligament, at a point midway between the anterior superior 
spinous process of the ilium and the symphysis pubis, where 
it can be felt pulsating. It descends the front of the thigh 
to its lower third, where it pierces the insertion of the adductor 
magnus muscle to reach the back of the thigh and become the 
popliteal. As long as it lies on the front of the thigh, that is, 
for the upper two-thirds of its course, it is known as the femoral 
artery; as soon as it reaches the lower third and appears on the 
back of the thigh it is called popliteal. 
A line drawn from about the middle of Poupart's ligament 
to the inner aspect of the internal condyle will indicate the 
course of the femoral artery, which lies behind the upper two- 
thirds of the line. 
Relations. For the first half or third of its course the femoral 
artery is superficial, lying in Scarpa's triangle, having the sar- 
torius to its outer side and the adductor longus to its inner 
side. It enters the triangle about the middle of the base and 
passing through the centre leaves it usually about at its apex DESCRIPTIVE ANATOMY. 
378 
by passing beneath the sartorius. It then descends, lying on 
the front of the insertion of the adductor longus, which relation 
it maintains to within about an inch or so of its termination, 
and for that distance it is separated from the posterior face 
of the sartorius by a tendinous arch which the adductor longus 
and adductor magnus throw over the artery to the vastus in- 
ternus; so that the last inch or two of the femoral artery is 
the deepest portion, being covered by the skin, superficial fascia, 
fascia lata, sartorius and the tendinous arch above mentioned. 
Throughout its course the artery lies between the sartorius 
and adductor longus. 
In the upper part of its course these muscles lie one on either 
side, while below the sartorius is in front and the adductor 
longus behind. For the last inch or two the sartorius is sepa- 
rated from the artery by the tendinous arch. Behind, the artery 
rests on the pectineus, adductor brevis, longus and magnus 
muscles, and has the psoas magnus to its outer side, above, 
but behind when that muscle crosses to its insertion. To its 
outer side is the vastus internus muscle. Throughout its course 
the artery is covered by the fascia lata. 
Relations to Cords. It lies in a sheath which also contains 
the femoral vein. At Poupart's ligament, the vein is internal 
and abreast of the artery; but as it descends, passes outward, 
so as to get first behind and then external. The crural branch 
of the genito-crural nerve crosses the artery in front in its 
upper part. In the upper portion of its course the artery has 
from one-fourth to one-half an inch to its outer side the anterior 
crural nerve, which here divides into numerous branches. Of 
these the internal cutaneous crosses the front of the artery, as 
does the middle cutaneous when piercing the sartorius muscle. 
The long saphenous, accompanied by the nerve to the vastus 
internus, descends as an external relation to the femoral, which 
relation is maintained until the nerve to the vastus enters the 
fibres of that muscle. The saphenous, on reaching Hunter's 
canal, gets directly in front of the vessel, usually in the canal, 
but not in its sheath. The two structures then separate, the 
artery passing to the back of the thigh, while the nerve con- 
tinues down to the inner side of the knee-joint. The nerve THE VASCULAR SYSTEM. 
379 
to the pectineus, when that muscle is supplied by the anterior 
crural, passes behind the artery in the upper portion of the 
vessel. At a variable distance from Poupart's ligament, some- 
times not more than half an inch, while occasionally more than 
two inches, there arises a large trunk, known as the deep 
femoral or profunda femoris. At its origin this vessel is external 
to the femoral; but quickly passes downward and inward and be- 
comes a posterior relation, which position it maintains until the 
two vessels are separated by the adductor longus muscle. Both 
the superficial and the deep femoral vessels are accompanied by 
their veins. The relations between these structures is usually that 
the two veins are interposed between the two arteries so that 
a cross-section of the limb would exhibit from before backward, 
femoral artery, femoral vein, profunda vein, profunda artery. 
It should be remembered, however, that in a large number of 
cases (probably as many as one-fourth) the relation is, femoral 
artery, femoral vein, profunda artery, profunda vein. 
Branches. 
Superficial Epigastric. 
Deep External Pudic. 
Superficial Circumflex Iliac. 
Profunda Femoris. 
Superficial External Pudic. 
Anastomotica Magna. 
Muscular. 
Soon after its commencement the femoral artery gives off four 
small branches; the superficial epigastric, the superficial cir- 
cumflex iliac, the superficial external pudic, and the deep ex- 
ternal pudic. These are all cutaneous. 
Superficial Epigastric. 
The superficial epigastric frequently arises by a common 
trunk with the superficial circumflex iliac. It first passes up- 
ward and inward, then continues its course nearly directly 
toward the umbilicus, lying beneath the skin and superficial 
fascia. It is distributed to the skin near the lower portion 380 
DESCRIPTIVE ANATOMY. 
of the abdominal wall; and anastomoses with the cutaneous 
branches of the deep epigastric. 
Superficial Circumflex Iliac. 
The superficial circumflex ILIAC, arising either in common 
with the superficial epigastric, or separately from the femoral, 
passes upward and outward, parallel with Poupart's ligament, 
toward the crest of the ilium. It supplies the superficial in- 
guinal glands, the skin of the upper front portion of the thigh; 
and inosculates with the superficial branches of the deep cir- 
cumflex iliac. 
Superficial External Pudic. 
The superficial external pudic arises from the inner aspect 
of the femoral, and passes in front of the femoral vein toward 
the genital organs. This artery either passes through the fascia 
lata or through the cribriform fascia covering the saphenous 
opening. It passes to the skin covering the pubes and supplies 
that, one branch passing along the dorsum of the penis, while 
the other branches are distributed to the scrotum in the male 
and the labia in the female. 
Deep External Pudic. 
The DEEP external pudic sometimes arises in common with 
the superficial external pudic, runs inward behind the femoral 
vein, then passes across the pectineus muscle and perforates the 
fascia lata close to the symphysis pubis. It inosculates with 
branches of the superficial perineal artery, and supplies the scro- 
tum and perineum in the male and the labia in the female. 
Profunda Femoris. 
At a variable distance from its commencement, generally from 
one to two inches, though sometimes less and somteimes more, 
the femoral artery gives off from it outer posterior aspect a 
branch called the profunda femoris which is almost as large as THE VASCULAR SYSTEM. 
381 
the continuation of the femoral itself. The direction of the pro- 
funda is for a short distance downward and outward, then curv- 
ing inward, almost immediately after its origin, it descends ver- 
tically lying behind the femoral artery and having no muscle 
interposed between them until the two reach the upper edge of 
the adductor longus, which muscle thence forward separates 
them, the femoral passing down on its front and the profunda 
behind it for some distance, and then, perforating the adductor 
magnus, passes to the back of the thigh where it is distributed. 
The profunda artery is contained in a sheath in which lies 
also its vein, which is usually in front of the artery. As the 
profunda descends behind the femoral it is separated from it 
by two veins, profunda and femoral; so that from the origin 
of the profunda down to the adductor longus muscle, the struc- 
tures usually lie in the following order from before backward; 
femoral artery, femoral vein, profunda vein, profunda artery. 
But sometimes the profunda vein lies behind the profunda 
artery. 
Branches of the Profunda. 
External Circumflex 
Three Perforating. 
Internal Circumflex 
The external circumflex arises early from the profunda and 
passes outward around the upper extremity of the femur, giving 
off two sets of branches, one ascending to the gluteal region and 
the other descending to the outer aspect of the thigh and knee- 
joint. These branches supply the muscles on the outer front 
aspect of the thigh, anastomosing above with the gluteal, behind 
with the internal circumflex, perforating and sciatic, and below 
with the superior external articular. 
The internal circumflex arises from the profunda near its 
commencement and is much smaller than the external circum- 
flex. It passes inward around the upper extremity of the femur 
and anastomoses with the external circumflex, superior perforat- 
ing and obturator. In addition to supplying the muscles on the 
inner aspect of the thigh, this vessel gives a branch to the hip- 
joint. 382 
DESCRIPTIVE ANATOMY. 
The three perforating arteries. As the profunda femoris is 
descending it gives off in succession three branches, each called 
perforating, superior, middle and inferior. They derive their 
names from the fact that they perforate the adductor magnus 
muscle (the superior perforating the adductor brevis also) to 
reach the back of the thigh and supply the posterior femoral 
muscles. 
Anastomotica Magna. 
The anastomotica magna, the last branch of the femoral 
artery, arises from it just as that artery is about to pierce the 
adductor magnus, and descends toward the knee after dividing 
into a superficial and a deep branch. The anastomotica magna 
divides into a superficial branch which follows the long saphe- 
nous nerve beneath the sartorius and is distributed to the skin; 
and a deep branch which, plunging into the vastus internus 
muscle, anastomoses with the superior internal and external 
articular branches of the popliteal and with the recurrent 
branch of the anterior tibial. 
Besides the six foregoing branches the femoral artery gives 
off muscular branches to the muscles in its course. 
The Popliteal Artery. 
The popliteal artery begins by being a continuation of the 
femoral, where that vessel terminates at the lower third of the 
femur by passing to the back of the thigh through the opening 
in the adductor magnus muscle. Its course is downward and 
outward (the obliquity being greatest at first) through the pop- 
liteal space to the lower border of the popliteus muscle, in front 
of the tendinous arch of the soleus-a point which corresponds 
to the junction of the upper fifth with the lower four-fifths of 
the shaft of the tibia-where it terminates by dividing into the 
anterior and posterior tibial arteries. 
Relations. The artery lies in the popliteal space in relation- 
ship with the muscles forming its walls, covered by the popliteal 
fascia and surrounded by a mass of fat which occupies the space. 
In entering the space it passes beneath the inner ham-string THE VASCULAR SYSTEM. 
383 
muscles, and hence enters below the upper angle of the space 
and on its inner wall. The biceps is to its outer side and diverges 
from the artery as the latter descends. The heads of the gas- 
trocnemius are distant external and internal relations in the 
middle of the vessel, but become closer and superficial relations 
towards its termination, owing to their convergence. The artery 
rests first on the lower third of the femur, then on the posterior 
ligament of the knee-joint and then on the fascia covering the 
popliteus muscle. 
Relations to Cords. In the popliteal space are found the pop- 
liteal artery and vein and the internal popliteal nerve. The 
artery and vein enter the space together, on its inner side below 
the superior angle, with the vein behind and external to the 
artery and closly adherent to it. As the structures descend the 
vein crosses the artery, and, while remaining behind, becomes 
also internal. The nerve enters the space at its apex, and is, 
consequently, external to the artery and vein as well as behind. 
As the artery is inclined outward and the nerve inward this re- 
lation changes so that the nerve becomes internal and behind. 
From behind forward, throughout the course of these structures, 
the order is nerve, vein, artery. In the upper third the vein and 
nerve are behind and external, the vein closely hugging the 
artery; in the middle third the vein and nerve are directly be- 
hind; in the lower third the vein and nerve are behind and in- 
ternal. The great sciatic nerve rarely divides at the apex of 
the popliteal space, so that it is more correct to say that the 
great sciatic is the posterior-external relation for the upper third 
and the internal popliteal is the relation for the lower two- 
thirds. 
Branches. 
Muscular 
Superior External Articular 
Inferior External Articular 
Inferior Internal Articular 
Superior Internal Articular 
Azygos Articular. 
The muscular branches of the popliteal consist of two sets, 
superior and inferior. The superior are several small branches 
given off to the ham-string muscles, while the inferior consist 384 
DESCRIPTIVE ANATOMY. 
usually of two large branches, called the sural, which are dis- 
tributed to the two heads of the gastrocnemius muscle and to 
the plantaris. 
The articular arteries, five in number, form a vascular zone 
around the knee joint, aided by the anastomotica magna from 
the femoral, the external circumflex from the upper part of the 
profunda femoris, and a recurrent branch from the anterior 
tibial. They consist of two sets, superior and inferior, each set 
consisting of two arteries. 
The superior external articular passes beneath the tendon of 
the biceps muscle, around the outer aspect of the knee joint 
above the external condyle, and anastomoses with the external 
circumflex branch of the profunda, with the terminal branch of 
the anastomotica magna, the inferior external and superior in- 
ternal articular arteries. 
The superior internal articular, passing beneath the tendon of 
the adductor magnus, winds around above the inner condyle of 
the femur, anastomosing with the anastomotica magna, the su- 
perior external articular, and the inferior internal articular. 
The inferior external articular winds around the head of the 
fibula below the outer tuberosity of the tibia, anastomosing with 
the superior external articular, the recurrent from the anterior 
tibial, and the inferior internal articular. 
The inferior internal articular passes beneath the internal tu- 
berosity of the tibia, anastomosing with the superior internal, 
and inferior external articular arteries, and, across the patella, 
with the superior external articular, and the anterior tibial re- 
current. 
The azygos articular consists of one or two small branches, 
which, rising opposite the posterior ligament of the knee joint, 
pierce that ligament to pass into the interior of the joint and 
supply the structures found there. 
The Posterior Tibial Artery. 
The POSTERIOR TIBIAL artery, one of the two terminal branches 
of the popliteal, begins where that artery terminates at the lower 
border of the popliteus muscle, beneath the tendinous arch of THE VASCULAR SYSTEM. 
385 
the soleus and descends the back of the leg with a steady inclina- 
tion inward to the inner aspect of the os calcis, where it di- 
vides, midway between the internal malleolus and posterior tu- 
berosity of the os calcis, into the internal and external plantar 
arteries. 
Relations. The posterior tibial artery, for about the upper 
two-thirds of its course, lies deep, covered by the triceps surae, 
but for the rest of its course it is superficial, having emerged 
to the inner side of the tendo Achilles, because of its own in- 
ward inclination and because of the narrowing of the triceps 
surae to a tendon. It is covered throughout its course by the 
transverse intermuscular septum, which is much stronger below 
than above. It lies on the tibialis posticus, the flexor longus digi- 
torum, the tibia, and on the ankle joint. 
The artery is accompanied by satellite veins, one on either side, 
and by the posterior tibial nerve. The nerve for the first few 
inches of the artery (at the lower part of the upper third of 
the leg) lies to the inner side of the artery and then crosses it 
posteriorly to assume a continuous external relation. The nerve 
crosses about where the peroneal branch arises. 
The relations at the ankle joint from within outward are as 
follows: first, the tendon of the tibialis posticus, then the tendon 
of the flexor longus digitorum, these tendons lying in the same 
groove, next comes the artery with a satellite vein on either side, 
then the posterior tibial nerve and about one-half an inch more 
external is seen the tendon of the flexor longus hallucis. 
Branches. 
Peroneal 
Internal Plantar 
External Plantar 
Internal Calcanean 
Terminal 
Besides muscular branches to the muscles in its course, and 
its two terminal branches, the posterior tibial produces two 
branches, peroneal and internal calcanean. One of its earliest 
muscular branches gives off a recurrent branch which passes 
upward to the knee-joint. 386 
DESCRIPTIVE ANATOMY. 
The peroneal artery is nearly as large as the continuation of 
the posterior tibial, and arises from that artery high up, near 
its origin, the distance being about two inches. It first passes 
obliquely downward and outward to the origin of the flexor 
longus pollicis muscle and then descends vertically beneath that 
muscle to terminate on the outer side of the os calcis. 
Relations. The peroneal in the upper, oblique, part of its 
course is covered, like its parent, by the triceps surae muscle, 
but after reaching the flexor longus pollicis it is covered by that 
muscle in addition. In the lower part of the leg the difference 
between the two arteries in depth is very considerable, since 
the posterior tibial is here superficial while the peroneal is still 
covered by the flexor longus pollicis and the tendo Achilles. It 
lies on the tibialis posticus and flexor longus hallucis. 
Just above the posterior tuberosity of the os calcis the peroneal 
and posterior tibial arteries are connected by a small trans- 
verse communicating branch. The peroneal gives muscular 
branches to the muscles in its course. About the lower third 
of the leg the peroneal gives off a large branch called the anterior 
peroneal, which pierces the interosseous membrane to reach the 
front of the leg. The termination of the peroneal is distributed 
on the outer side of the heel by branches called external cal- 
canean. 
The internal calcanean branches of the posterior tibial are 
three or four in number and are distributed to the inner side of 
the heel. They anastomose with the peroneal, external calca- 
nean, internal malleolar and plantar arteries. 
The Internal Plantar Artery. 
The internal PLANTAR (plantaris medialis), much the smaller 
of the two terminal branches of the posterior tibial, begins where 
that artery bifurcates midway between the posterior tuberosity 
of the os calcis and the internal malleolus and passes forward 
along the inner side of the sole, covered by the abductor pollicis 
and then between it and the flexor brevis pollicis, to terminate 
on the inner side of the great toe by inosculating with the THE VASCULAR SYSTEM. 
387 
digital branch to that toe, having given off muscular branches 
in its course. 
The External Plantar Artery. 
The EXTERNAL PLANTAR (plantaris lateralis), the larger and 
more important of the two terminal branches of the posterior 
tibial, begins where that artery bifurcates midway between the 
posterior tuberosity of the os calcis and the internal malleolus, 
and passes forward and outward between the first and second 
layers of muscles in the sole to the base of the fifth metatarsal 
bone, where it turns inward beneath the second layer of the 
muscles to cross to the inner side of the sole and terminate there 
at the posterior extremity of the first interosseous space by 
anastomosing with a communicating branch from the dorsalis 
pedis artery, thus forming the magna pollicis. That portion of 
the artery which crosses the sole from the outer to the inner 
side is called the plantar arch. 
Branches. 
Bsides muscular branches, the external plantar gives off the 
following: digital and posterior perforating. 
The digital branches are four in number. They run forward 
to the cleft between the toes and there divide to supply plantar 
collateral branches to the sides of the toes, except the great toe 
and the inner side of the second toe. The outermost of the four 
is appropriated by the outer side of the little toe. Just before 
the digital arteries divide at the clefts of the toes, they each 
send up between the metatarsal bones a branch called anterior 
perforating, to open into the digital branches on the dorsum of 
the foot. 
The posterior perforating, three in number, pass up between 
the heads of the three outer interosseous muscles to anastomose 
with the metatarsea artery on the dorsum of the foot. 
The Anterior Tibial Artery. 
The ANTERIOR tibial artery begins where the popliteal forks, 
at the lower border of the popliteus muscle, beneath the ten- 388 
DESCRIPTIVE ANATOMY. 
dinous arch of the soleus, and passes directly forward between 
the tibia and fibula to the front of the leg which it descends, 
lying, for the upper two-thirds of its course, on the interosseous 
membrane, and for the lower third on the front of the tibia, to 
terminate on the middle of the front of the ankle-joint, beneath 
the annular ligament, by assuming the name of dorsalis pedis. 
Relations. The anterior tibial is divided into three portions- 
upper, middle and lower thirds. 
In its upper third it lies on the front of the interosseous mem- 
brane between the tibialis anticus internally and the extensor 
longus digitorum externally. In its middle third it still lies on 
the interosseous membrane, but has reached the origin of the 
extensor proprius pollicis and this muscle lies on the outer side, 
while the tibialis anticus still remains internal. 
In its lower third it lies on the front of the tibia and is crossed 
obliquely by the tendon of the extensor proprius pollicis, which 
displaces the tibialis anticus and becomes the internal relation, 
while the extensor longus digitorum again comes into relation 
with it externally. 
The artery is accompanied by satellite veins and the anterior 
tibial nerve. The nerve is at first to its outer side; then for a 
short distance in front of it and then again to the outer side. 
Branches. 
The branches of the anterior tibial artery are muscular, a re- 
current branch, which ascends to the front of the knee through 
the tibialis anticus muscle, and two malleolar branches, external 
and internal, which surround the tibia just above the ankle- 
joint and supply that joint. 
The inner malleolar passes beneath the tibialis anticus and 
extensor proprius where it inosculates with the internal calca- 
nean, internal plantar and branches of the posterior tibial often 
supplying the inner side of the ankle. 
The external malleolar passes beneath the extensor longus 
digitorum and, after supplying the outer side of the ankle, 
inosculates with the tarsea and the termination of the anterior 
peroneal. THE VASCULAR SYSTEM. 
389 
Dorsalis Pedis. 
The dorsalis pedis artery is the continuation of the anterior 
tibial. It begins beneath the annular ligament, about the mid- 
dle of the front of the ankle-joint, and passes forward along 
the inner side of the dorsum of the foot to terminate at the 
posterior extremity of the first interosseous space by dividing 
into the dorsalis hallucis and the communicating. 
Relations. It has similar relations to muscles and cords as 
the lower third of the anterior tibial. To its inner side is the 
extensor proprius pollicis tendon, to its outer side the extensor 
longus digitorum, and near its termination it is crossed by the 
tendon of the extensor brevis digitorum to the great toe. It 
lies between satellite veins and has the anterior tibial nerve 
to its outer side. 
Branches. 
Tarsea 
Dorsalis Hallucis 
Metatarsea 
Communicating. 
The tarsea branch passes outward on the tarsus. 
It lies beneath the extensor brevis digitorum, which it sup- 
plies, along with tarsal articulations, and anastomoses with the 
metatarsea, external plantar and malleolar and the termination 
of the anterior peroneal. 
The metatarsea branch passes outward on the bases of the 
metatarsal bones and receives the posterior perforating branches 
from the plantar arch. The metatarsea sends forward three 
branches called interosseous, which after receiving the anterior 
perforating branches of the plantar digital arteries, divide at 
the clefts of the toes to form collateral digital branches for the 
dorsal aspect of the fifth, fourth and third toes and the outer 
side of the second toe. 
The dorsalis hallucis is one of the two terminal branches of 
the dorsalis pedis, and runs forward to supply dorsal collateral 
digital branches for the great toe and inner side of the sec- 
ond toe. 390 
DESCRIPTIVE ANATOMY. 
The communicating passes through the first interosseous space 
to anastomose with the termination of the external plantar, 
forming the magna pollicis, which passes forward and divides 
to form plantar collateral digital branches for the great toe and 
inner side of the second toe. 
Internal Iliac Artery. 
The internal ILIAC (a. hypogastrica), one of the two terminal 
branches of the common iliac, commences where that artery 
bifurcates on the side of the disc between the fifth lumbar ver- 
tebra and the sacrum, and passes downward into the pelvis over 
the front of the sacro-iliac symphysis to the upper margin of 
the great sacro-sciatic notch, where it divides into the anterior 
and posterior trunks. Its length is variable, and is usually 
about two inches. It is a short and large trunk. 
Relations. It lies behind the peritoneum, has the ureter upon 
its front, and rests behind upon the lumbo-sacral cord and the 
pyriformis muscle and internal iliac vein. On the left side it 
has resting upon it the end of the sigmoid flexure of the colon. 
The distribution of the vessel is to the viscera and walls of 
the pelvis, and with few exceptions it will be found that the 
parietal branches spring from the posterior, while the visceral 
are the offspring of the anterior trunk. The hypogastric artery 
of the foeetus is a branch of the internal iliac. It is nearly ob- 
literated after birth, becoming an impervious cord from the 
bladder to its point of attachment to the abdominal wall; but 
from the internal iliac to the wall of the bladder the artery is 
pervious, and carries some of the arterial supply of that viscus. 
Branches of the Anterior Trunk. 
Hypogastric 
Obturator 
Inferior Vesical 
Terminal 
Ischiatic 
Middle Hemorrhoidal 
Internal Pudic 
Uterine 
In female 
Vaginal THE VASCULAR SYSTEM. 
391 
Hypogastric. 
The first of these branches, the obliterated hypogastric, 
passes from the front of the anterior trunk to the posterior sur- 
face of the bladder. This artery conveys but a small amount 
of blood, which is transmitted to the bladder by two small ves- 
sels, known as the superior and middle vesical arteries. They 
are distributed to the apex and greater portion of the body of 
the bladder, while a small twig from one is generally given to 
the vas deferens. 
Inferior Vesical. 
The inferior vesical, springing directly from the anterior 
trunk is distributed to the base of the bladder, and in the male 
subject, passes forward also to the prostrate gland and to the 
seminal vesicles. 
Middle Hemorrhoidal. 
The next branch, the middle hemorrhoidal, which fre- 
quently arises in common with the inferior vesical, passes to 
the rectum, and supplies the middle portion of that gut, anasto- 
mosing above with the superior hemorrhoidal and below with 
the inferior hemorrhoidal branches of the internal pudic. 
Obturator. 
The obturator is the largest of the way-side branches of the 
anterior trunk. It is very variable in its origin. Generally the 
product of the anterior trunk, it sometimes springs from the 
deep epigastric branch of the external iliac; and in a few cases 
may be found arising from the posterior trunk of the internal 
iliac. Its usual course is to pass along the wall of the pelvis 
just below its brim, accompanied by the obturator vein and 
nerve, the nerve lying above the artery and the vein below. It 
lies behind the peritoneum, between it and the parietal pelvic 
fascia, reaches the upper margin of the thyroid foramen, and 
leaves the pelvic cavity by passing through this foramen in an 
opening left above the obturator membrane. While in the pel- 392 
DESCRIPTIVE ANATOMY. 
vic cavity it gives off a small branch, which passes into the iliac 
fossa to supply the bone, and a minute twig which ramifies upon 
the posterior face of the pubic arch, anastomosing there with 
the pudic branch of the deep epigastric. After emerging from 
the pelvic cavity, it divides into two branches, external and in- 
ternal. Of these the external, which is the larger, skirts the 
outer margin of the obturator foramen, and divides into two 
branches, one of which anastomoses with the internal division 
of the obturator and the other with the internal circumflex, the 
artery supplying the muscles around the tuberosity of the 
ischium in its course. The internal branch, skirting the inner 
margin of the obturator foramen, supplies the muscles around 
that foramen and the adductor muscles, anastomosing with the 
internal circumflex and with the external division of the obtu- 
rator. The external branch also anastomoses with the ischiatic. 
After giving off the preceding branches, the anterior trunk 
divides into two terminal branches, the ischiatic, or sciatic, and 
the internal pudic. 
Ischiatic. 
The ischiatic artery leaves the pelvis through the great 
sacro-sciatic foramen below the pyriformis muscle. It descends 
between the trochanter major and the tuberosity of the ischium, 
crossing the external rotators of the thigh, and passing down- 
ward on the inner side of the great sciatic nerve. It inosculates 
with the internal circumflex and superior perforating branch 
of the profunda, and gives off muscular branches to the mus- 
cles in its course. Besides these, it gives coccygeal branches 
within the pelvis, which pierce the great sacro-sciatic ligament 
to supply the gluteus maximus muscle; and a rather large 
branch, called the inferior gluteal, passing to the deep surface 
of the same muscle; an articular branch to the hip joint, given 
off external to the pelvis; cutaneous branches to the integument 
of the gluteal region; and a branch which accompanies the* 
sciatic nerve, called the comes nervi ischiatici. THE VASCULAR SYSTEM. 
393 
Internal Pudic. 
The internal pudic is the second and smaller of the two 
terminal branches of the anterior trunk of the internal iliac. 
It lies in front of the ischiatic; and passes downward over the 
sacral plexus of nerves, parallel with that artery, to leave the 
pelvis through the greater sacro-sciatic foramen below the pyri- 
formis muscle. It then continues its course to the spine of the 
ischium, winds around that process, re-enters the pelvis through 
the lesser sacro-sciatic foramen lying about an inch above the 
tuberosity of the ischium, and passes upward and forward along 
the ramus of the ischium, or rather the obturator internus mus- 
cle, held in position by a fold of the pelvis fascia, until it reaches 
a point opposite the transversus perinaei or near the central 
point of the perineum, where it divides into a superficial and 
a deep perineal branch. 
The superficial perineal passes forward through the perineum 
as far as the scrotum. At the upper border of the transversus 
perinaei it gives off a branch bearing the same name as that 
muscle, which crosses on that muscle, supplies it and the adja- 
cent portion of the skin, and anastomoses with its fellow of the 
opposite side. 
While the internal pudic is still in the pelvic cavity it gives 
off inferior hemorrhoidal branches. These branches perforate 
the pelvic fascia, which holds the artery in position, and pass to 
the anus, where they supply the sphincter and levator ani mus- 
cles, anastomosing with the middle hemorrhoidal and with the 
vessels of the opposite side. 
The deep perineal continues the course of the internal pudic, 
passing between the two layers of the triangular ligament, and 
opposite the junction of the crura of the penis divides into two 
branches, the dorsal artery of the penis and the artery of the 
corpus cavernosum. 
Prior to this division it gives off a large branch, the artery of 
the bulb, which enters the bulb of the corpus spongiosum and is 
distributed to that structure. It is a very short trunk, which 
passes transversely inward between the layers of the triangular 
ligament to plunge at once into the bulb of the penis. 394 
DESCRIPTIVE ANATOMY. 
The artery of the corpus cavemosum, one of the terminal 
branches, enters the crus penis on its inner aspect, and is dis- 
tributed in that body. 
The dorsal artery of the penis, the other terminal branch, con- 
tinues upward between the two layers, lying in the substance 
of the compressor urethrae muscle. It pierces the anterior layer 
near its apex, and then the suspensory ligament of the penis, 
and passes along the dorsum of the penis to the corona to anas- 
tomose with the artery of the opposite side. In this course it is 
accompanied by the corresponding nerve, which lies to the outer 
side of the artery. This artery anastomoses with the deep ex- 
ternal pudic branch of the femoral, which has been known to 
take its place. 
Branches of the Posterior Trunk. 
Ilio-Lumbar 
Lateral Sacral 
Gluteal 
Ilio-Lumbar. 
The ilio-LUMBAR is a short recurrent branch, which arising 
from the postero-external part of the internal iliac, passes up- 
ward and outward beneath the common iliac artery. It passes 
between the lumbo-sacral cord and the obturator nerve, and then 
beneath the psoas magnus muscle, and divides into two branches, 
iliac and lumbar. 
The iliac branch passes between the iliacus internus muscle 
and the iliac fossa, is distributed to that muscle, and sends a 
nutrient artery to the bone. 
The lumbar branch, passing beneath the psoas magnus, sup- 
plies that muscle and the quadratus lumborum, and sends a 
spinal branch into the foramen between the last lumbar ver- 
tebra and the sacrum. 
Lateral Sacral. 
The lateral sacral are a pair of small arteries, the superior 
of which enters the first anterior sacral foramen, where it com- 
municates with branches of the lumbar arteries above, and with THE VASCULAR SYSTEM. 
395 
branches of the lower lateral sacral below. The inferior passes 
downward on the front of the sacrum, and sends a branch into 
each anterior sacral foramen, except the first, these branches 
communicating with one another, and also with the superior 
lateral sacral above. 
Gluteal. 
The gluteal artery is a continuation of the posterior trunk 
of the internal iliac. It passes backward through the upper part 
of the great sacro-sciatic foramen above the pyriformis muscle, 
usually piercing the sacral plexus of nerves. After emerging 
from the pelvis, it divides into two branches, a superficial and 
a deep, the superficial passing outward between the gluteus 
maximus and the gluteus medius muscles to supply the former, 
and, perforating it, to be distributed to the integument. 
The deep branch, itself subdividing into two, runs between 
the gluteus medius and minimus, and gives branches to these 
two muscles. The superior division of the deep branch anas- 
tomoses with the circumflex iliac, and with the external circum- 
flex. 
The inferior division anastomoses with the external circum- 
flex. 
The superficial branch anastomoses with the posterior 
branches of the sacral arteries. 
Internal Carotid. 
The internal carotid artery is one of the two terminal 
branches of the common carotid; and begins where that vessel 
terminates on the upper border of the thyroid cartilage oppo- 
site the transverse process of the fourth cervical vertebra, and 
passes upward on the front of the transverse processes of the 
three upper cervical vertebrae to the carotid aperture on the 
basilar surface of the petrous portion of the temporal bone. 
Entering at this foramen, it abruptly changes its course to pass 
inward and forward, with a slight inclination downward, run- 
ning in the carotid canal, to an aperture of exit near the apex 
of the petrous portion of the temporal, where it again changes 396 
DESCRIPTIVE ANATOMY. 
its direction, passes upward to enter the cavity of the cranium, 
turns forward, lying in the cavernous groove by the side of 
the sella Turcica, and finally passes upward beside the anterior 
clinoid process, and divides into four terminal branches, anterior, 
cerebral, middle cerebral, posterior communicating, and anterior 
choroid. 
Relations. Its relations to muscles and structures through- 
out its course are as follows: Behind it are the anterior tuber- 
cles of the transverse process of the three upper cervical ver- 
tebrae separated from the artery by the origin of the rectus 
capitis anticus major. In front, it is at first covered by the 
skin, superficial and deep fascia, platysma, stylohyoid and digas- 
tric muscles, and at its commencement by the anterior border 
of the sterno-cleido-mastoid. As it ascends, however, it passes 
beneath the parotid gland, the stylo-glossus and stylo-pharyn- 
geus muscles and the stylo-hyoid ligament. To its inner side 
is the pharynx, and the tonsil, which is a more distant internal 
relation. 
The relations to cords are numerous and important. At its 
commencement the internal carotid is external to the external 
carotid artery; but as it ascends the neck and reaches the stylo- 
hyoid and posterior belly of the digastric muscles, the internal 
passes behind the external and is thenceforward separated from 
it by the stylo-glossus and stylo-pharyngeus muscles and stylo- 
hyoid ligament, and the pharyngeal branch of the pneumogas- 
tric. Through the greater portion of its course the internal 
jugular vein lies to its outer side, as does the pneumogastric 
nerve; but near the apertures of entrance the relations are more 
numerous and more complex. An examination of the skull will 
show that the jugular foramen is directly behind the carotid 
aperture of entrance, and that the anterior condyloid foramen 
is behind and internal to this. Hence the relations which these 
structures bear to each other. At the point of entrance of the 
carotid artery the internal jugular vein and the ninth, tenth, 
and eleventh nerves lie directly behind the artery, while the 
twelfth nerve is behind and slightly internal. The ninth, tenth 
and twelfth quickly emerge between the artery and the vein, 
while the eleventh passes behind the vein. The relation, then, im- THE VASCULAR SYSTEM. 
397 
mediately after emergence from their respective foramina would 
be: the artery the most internal of all the structures lying 
against the wall of the pharynx, the most external the internal 
jugular vein, and between these the ninth, tenth, and twelfth 
nerves. At the lower border of the stylo-glossus muscle the 
glosso-pharyngeal nerve crosses over the front of the artery, 
and ceases to be a relation. 
The hypoglossal, or twelfth, nerve now becomes an antero-ex- 
ternal relation until it reaches the lower border of the stylo- 
hyoid and posterior belly of the digastric, when it crosses the 
external carotid artery directly in front to reach its point of 
distribution, while the pneumogastric, or tenth, continues down- 
ward as an external relation, lying between the artery and the 
vein. • Posteriorly the artery rests upon the cervical portion of 
the sympathetic, which separates it from the rectus capitis anti- 
cus major muscle. The interosseous, or petrosal, portion of 
the artery requires no description, being imbedded in the petrous 
portion of the temporal bone. The intra-cranial portion lying 
in the cavernous sinus, has the sixth nerve lying upon its outer 
side. The artery is covered by the lining membrane of the sinus; 
and is not in direct contact with the blood which flows through 
that sinus. 
Branches. 
The first portion gives off no branches. The second portion 
produces one unimportant branch, the tympanic, which passes 
to the tympanum. The third portion gives origin to three 
branches. Two of these, the arteria receptaculi, are unim- 
portant and are distributed to the cavernous sinus and dura 
mater; the third is an important branch, the ophthalmic artery. 
The Ophthalmic Artery. 
The ophthalmic artery springs from the internal carotid 
about the termination of its third portion and passes forward 
into the orbit through the optic foramen, first lying below and 
external to the optic nerve, then crossing to the inner side of the 
nerve and running forward along the inner wall of the orbit 398 
DESCRIPTIVE ANATOMY. 
to divide at the internal angle of the orbit into two branches, 
frontal and nasal. 
Branches. 
The branches of the ophthalmic artery are ten in number. 
The lachrymal artery runs forward along the outer wall of 
the orbit and after supplying the lachrymal gland passes on to 
the upper eye-lid. It gives off temporo-malar branches which 
pass through the bone to the temporal muscle. 
The supra-orbital runs forward on the levator palpebrae mus- 
cle and escaping to the forehead through the supra-orbital fora- 
men, is there distributed by a superficial and a deep branch, 
anastomosing with the frontal. 
The anterior and posterior ethmoidal arteries escape through 
the anterior and posterior ethmoidal foramina, and are distri- 
buted to the dura mater, ethmoidal cells and nasal fossse. 
The palpebral arteries, superior and inferior, arise from the 
ophthalmic near its termination. The superior runs outward 
on the upper lid near its free edge, between the orbicularis pal- 
pebrarum and the tarsal cartilage and is there distributed; the 
inferior does the same for the lower lid. The two sometimes 
arise by a common trunk. 
The frontal, one of the two terminal branches of the ophthal- 
mic artery, emerges at the inner angle of the orbit and ascends 
to be distributed along the middle of the forehead, anastomosing 
with the anterior branch of the temporal, with its fellow and 
with the supra-orbital. 
The nasal, the other terminal branch of the ophthalmic artery, 
emerges at the inner angle of the orbit and is distributed along 
the bridge of the nose, anastomosing with its fellow and with 
the facial through its angular and transverse nasal branches. 
The arteria centralis retinae pierces the optic nerve and runs 
forward in it to reach the retina and be there distributed. 
The ophthalmic gives off numerous micscular branches in its 
course which are divided into two sets, superior and inferior, 
the superior springing by one trunk and the inferior by another. 
Together they supply the muscles in the orbital cavity. They 
are very irregular in number and in point of origin. THE VASCULAR SYSTEM. 
399 
The ciliary arteries consist of three sets, viz: 
(a) Short ciliary branches, which are numerous small arteries 
which pierce the sclerotic around the optic nerve and supply 
the choroid. 
(b) Long ciliary, which are two branches piercing the sclero- 
tic on opposite sides and running forward between it and the 
choroid to be distributed to the iris. 
(c) Anterior ciliary branches, which are the offspring of mus- 
cular branches and pierce the sclerotic near the front of the eye 
to reach the iris. 
The branches from the fourth or cerebral portion, i. e., ter- 
minal branches, are four. 
Anterior Cerebral Artery. 
The anterior cerebral artery, one of the terminal branches 
of the internal carotid, runs forward in the longitudinal fissure, 
ascends the genu of the corpus callosum and runs backward 
along that body. It distributes branches to the frontal and 
parietal lobes of the brain, on their inner face, and inosculates 
with the posterior cerebral. Its branches are frequently given 
the names of the convolutions which they supply. 
Passing from the anterior cerebral of one side to that of the 
other, soon after their origin, is a communicating branch called 
the anterior communicating artery. 
Middle Cerebral Artery. 
The MIDDLE cerebral, arising as one of the terminal branches 
of the internal carotid, passes outward along the fissure of 
Sylvius to be distributed to the anterior and middle lobes of 
the cerebrum and to the convolutions forming the island of 
Reil. This artery gives off two sets of branches, one to the 
cortex and one to the ganglia in the interior of the brain. The 
cortical branches are distributed over the outer face of the 
frontal parietal and temporo-sphenoidal lobes, and receive the 
names of the convolutions which they supply. The ganglionic 
branches pierce the anterior perforated space and are distri- 400 
DESCRIPTIVE ANATOMY. 
buted in the interior of the cerebrum. An important fact con- 
cerning these two sets of branches is that they do not anastomose 
with each other in the brain. 
Anterior Choroid Artery. 
The anterior choroid pierces the temporo-sphenoidal lobe on 
the base of the brain to enter the descending cornu of the lateral 
ventricle and form the choroid plexus. 
Posterior Communicating Artery. 
The posterior communicating artery, the last of the four 
terminal branches of the internal carotid, passes backward to 
anastomose with the posterior cerebral of the basilar artery. 
From this artery are given off ganglionic branches which pass 
through the posterior perforated spot to the interior of the 
brain. 
Circumscribing the six-sided space at the base of the brain 
is a series of arteries and their communications forming what 
is called the vascular circle of Willis. Beginning in front we 
have the anterior communicating, and, following the arteries 
back on one side, they come in this order, anterior communicat- 
ing, anterior cerebral, internal carotid, posterior communicat- 
ing, posterior cerebral and the termination of the basilar artery. 
Following them forward from the basilar artery they come in 
the reverse order. 
THE VENOUS SYSTEM. 
The veins are the vessels which return the blood which the 
arteries have carried to the capillaries. Consequently the venous 
current passes in a direction opposite to that of the arterial, or 
towards the heart, opening into that organ by means of two 
main trunks, called the superior and inferior vena cavae, and by 
small vessels which carry the venous circulation of the heart 
itself. THE VENOUS SYSTEM. 
401 
The veins are divided into two sets, the superficial and the 
deep. The superficial veins are found between the layers of 
superficial fascia; and ultimately terminate by emptying into 
the deep veins. The deep veins are found accompanying the 
arteries, and are arranged in two forms: the smaller arteries 
are accompanied by satellite veins, one upon either side, while 
the larger vessels are accompanied by a single vein, bearing 
usually the name of the artery itself. 
The venous system as a whole is very much larger than the 
arterial system as a whole; and this statement is particularly 
true of the veins found in the abdominal cavity. These veins 
are capable of being greatly dilated upon stimulation of the 
splanchnic nerves, so that it is possible for an animal to bleed 
to death in the venous channels of the abdominal cavity with- 
out a drop of blood being extracted from the body, the veins 
dilating to such an extent as to be able to contain all of the blood 
of the system. 
As a rule the companion veins of an artery receive accessories 
corresponding to the number of branches which are emitted by 
the artery, though there are some notable exceptions to this. 
The Veins of the Lower Extremity. 
The veins of the lower extremity consist of two sets, super- 
ficial and deep. 
The deep veins, or satellite veins, commence in the sole of the 
foot on both sides of the plantar arteries, and on its dorsal sur- 
face, on both sides of the dorsalis pedis. 
The companion, or satellite, veins of the internal and external 
plantar arteries, commencing respectively on the inner and outer 
side of the sole, unite where the posterior tibial artery termi- 
nates, to form two companion veins for the posterior tibial. 
These veins ascend, lying, one upon either side of the posterior 
tibial artery and receive, about an inch below the beginning of 
that vessel the two companion veins of the peroneal artery, 
which have united to form a single vein. 
The satellite veins of the dorsalis pedis artery, commencing 
on the dorsum of the foot at the great toe, receive the veins from 402 
descriptive anatomy. 
the tarsal and metatarsal branches of that artery to become at 
the front of the ankle the companion veins of the anterior tibial. 
These veins then receive the accessory veins which accompany 
the branches of the anterior tibial artery, and continue their 
course up the leg, uniting to form a single vein, which, passing 
above the interosseous membrane joins the branch formed by 
the satellite veins of the posterior tibial artery to form the 
popliteal. 
Popliteal Vein. 
The popliteal vein then passes upward accompanied by the 
popliteal artery. It lies superficial to the artery, and between 
that structure and the internal popliteal nerve, lying at first 
behind and internal to the artery, directly behind it in the middle 
portion of its course, and behind and external in the upper part 
where the femoral artery terminates in the popliteal. It re- 
ceives the accessory veins which accompany the five articular 
branches, the muscular branches given off by the popliteal artery, 
and the short saphenos, and becomes the femoral vein at the 
junction of the lower third with the upper two-thirds of the 
shaft of the femur. 
Femoral Vein. 
The femoral vein then accompanies the femoral artery, re- 
ceiving in its course the veins which accompany the branches 
of that vessel. It lies first behind and external to the femoral 
artery, then shortly before the commencement of that vessel di- 
rectly behind it, and finally internal to it, so that at Poupart's 
ligament it is internal and fully abreast of the artery. About 
an inch and one-half below the commencement of the femoral 
artery, it gives off its profunda femoris branch, which artery 
is accompanied by its own vein formed by the various satellite 
veins accompanying branches from the profunda femoris. At 
the origin of the profunda this vein and the femoral vein unite, 
forming what is sometimes called the common femoral vein, 
which lies internal and abreast of its artery as just described. 
This vein at Poupart's ligament terminates by becoming the 
external iliac vein. Just before reaching Poupart's ligament, THE VENOUS SYSTEM. 
403 
the femoral vein, lying then opposite the saphenous opening of 
the fascia lata, receives the long or internal, saphenous vein and 
the satellite veins which accompany the superficial branches 
given off from the femoral in this situation. 
External Iliac Vein. 
After changing its name to become the external iliac, the 
vein receives the companion branches of the deep circumflex, 
and the deep epigastric branches of the external iliac artery. 
It then passes upward, lying first internal and abreast of the 
external iliac, and then internal and behind it to the point at 
which the common iliac artery divides into its two terminal 
branches, opposite the intervertebral disc between the fifth lum- 
bar vertebra and the sacrum. 
Common Iliac Vein. 
At this point it is joined by the internal iliac vein, which is 
made up of a large number of satellite veins accompanying the 
numerous branches of the internal iliac artery. The confluence 
of these two veins forms the common iliac, which is found lying 
first directly behind its artery, then external and on a plane pos- 
terior, and finally external to the common iliac artery, at the 
commencement of which vessel, opposite the body of the fourth 
lumbar vertebra, it unites with the common iliac vein of the 
opposite side to form the inferior vena, cava. 
This description applies only to the common iliac vein of the 
right side of the body. On the left side the external iliac vein is 
internal and abreast of its artery at Poupart's ligament, con- 
tinues internal, but on a plane posterior to it, up to the bifurca- 
ion of the common iliac artery, passes here behind the internal 
iliac, and is joined by the vein accompanying that artery, form- 
ing the common iliac vein of the left side, which vein is internal 
to the common iliac artery throughout its course; and finally 
passes behind the right common iliac artery to join with that 
vein opposite the fourth lumbar vertebra and form the inferior 
vena cava. 404 
descriptive anatomy. 
Internal Iliac Vein. 
The internal iliac vein is formed by the coalescence of the 
veins accompanying the branches of the internal iliac artery. 
The veins of the visceral branches are so numerous and inter- 
secting that they form plexuses. The vein thus formed ascends 
behind its artery and unites with the external iliac vein on the 
disk between the fifth lumbar vertebra and the sacrum to produce 
the common iliac vein. 
Inferior Vena Cava. 
The inferior VENA CAVA then continues its course, lying on 
the right side of the abdominal aorta. As it passes upward, 
it receives, opposite the centre of the body of each lumbar ver- 
tebra, the lumbar veins from the two sides of the body. These 
veins are usually four or five in number, those from the left 
side passing behind the abdominal aorta in order to reach the 
inferior vena cava. About opposite the lower border of the 
second lumbar vertebra, the renal veins, formed in the hilum 
of the kidneys, pass at right angles into the inferior vena 
cava, the vein from the left side passing across the front of the 
abdominal aorta generally, though occasionally behind it. The 
vena cava itself receives the supra-renal veins, and continuing 
its course upward, passes behind the posterior border of the 
liver, upon which it makes a deep notch, and there receives 
the hepatic veins. It then pierces the diaphragm on a level with 
the ninth dorsal vertebra, but on the right side of the body, 
through the highest and most anterior of the openings found 
in the diaphragm; and entering the base of the heart at the 
lower, inner, and back part of the venous auricle, pours its 
current into that organ. 
The Portal System. 
The blood which is poured into the inferior vena cava on the 
posterior border of the liver through the orifices of the hepatic 
veins is derived from a double source, a part of it coming from THE VENOUS SYSTEM. 
405 
the veins in which the capillaries of the hepatic artery terminate, 
while a part of it is the product of the portal system of veins, 
which drain the circulation of a large portion of the alimentary 
canal into the liver, where the veins ramify before uniting to 
form the hepatic veins. It will thus be seen that the liver re- 
ceives a double blood supply, one portion being that received 
from the hepatic artery, the ordinary arterial blood, which is 
intended for the nutrition of the liver tissue itself (paren- 
chyma), the other from the alimentary canal contains that 
blood which has absorbed the products of digestion, and which 
passes through the liver, not for the purpose of nourishing that 
organ, but in order to effect certain necessary changes in the 
blood before it is conveyed to the circulation. 
This portal SYSTEM of veins is formed in the following man- 
ner: the portal vein commences at the upper border of the 
pancreas by the union of the splenic and the superior mesen- 
teric veins. The splenic vein, before uniting with the superior 
mesenteric, receives behind the pancreas the inferior mesen- 
teric vein, which conveys the return circulation from the sig- 
moid flexure of the colon, and the descending colon. The supe- 
rior mesenteric vein carries the return circulation from the 
transverse colon, descending colon, coecum, and small intestines. 
Hence it will be seen that the greater portion of the blood 
from that part of the alimentary canal which serves for the 
digestion of food is carried through the superior mesenteric 
vein, but little absorption taking place in that part of the large 
intestine which lies below the formation of this vein. 
After the splenic and superior mesenteric veins have united 
behind the upper border of the head of the pancreas, the gastric 
veins, one of which accompanies the gastric artery and the 
other the arch formed by the inosculation of the gastro-epi- 
ploica dextra and sinistra, empty into the portal system, which 
also receives the small vein which accompanies the pancreatica 
magna artery and the pancreatico-duodenalis superior. The 
vein which accompanies the pancreatico-duodenalis inferior 
empties into the inferior vena cava before that reaches the 
splenic vein. 406 
DESCRIPTIVE ANATOMY. 
The splenic itself is formed by vessels which convey the 
return circulation from the spleen; and also receives the small 
veins accompanying the various branches given to the pancreas 
and the vasa brevia of the stomach. 
The portal vein, formed in this way, is a short, wide trunk, 
about two inches in length, which passes upward, lying in the 
right side of the lesser omentum. It lies behind the hepatic 
artery and common bile duct, but opposite the internal between 
these two structures, so that in naming them from right to left 
the order would be, common bile duct, portal vein, and hepatic 
artery, the usual statement being, duct to the right, artery to the 
left, vein between and behind the two. The vein now enters 
the transverse fissure of the liver, where it breaks up into 
numerous branches, which, following the lobules of that organ 
(see histology for description), unite into minute vessels, which 
in their turn unite again, until finally the hepatic veins are 
formed. 
These veins, three or four in number, open by orifices which 
remain patulous after death, into the inferior vena cava, as it 
is coursing along the posterior border of the liver. 
The Spermatic Veins. 
The spermatic VEINS are two in number, right and left. They 
begin in the scrotum, being formed by the plexus of veins sur- 
rounding each one of the testicles. These veins emerge from 
the back of the testicle; and receiving the tributaries from the 
epididymus forming a convoluted plexus, called the pampini- 
form plexus (L. pampinus, a tendril; forma, like). They then 
pass upward with the other elements of the spermatic cord. 
Entering at the superficial abdominal ring, they follow the 
course of the spermatic canal to enter the abdominal cavity 
through the deep abdominal ring. From this point the courses 
of the veins on the two sides differ. 
On the right side, the vein passes across the external iliac 
artery, gets to the outer side of that vessel; and passing up- 
ward with a steady inclination inward, terminates by entering 
at an acute angle into the inferior vena cava, the blood from THE VENOUS SYSTEM. 
407 
the spermatic vein going in the same direction as the blood 
in the vena cava. 
On the left side, it crosses the termination of the external 
iliac artery; but ascends vertically, and empties, not into the 
vena cava, but into the left renal vein, at right angles to that 
vein, so that the whole current of blood in the renal vein passes 
across the aperture of the left spermatic and retards the flow 
of blood from this vein. It is for these anatomical reasons 
that enlargement of the veins of the left testicles and scrotum 
so frequently occurs, the surgical disease, known as varicocele, 
arising from this cause. 
The Superficial Veins of the Lower Extremity. 
Returning to the lower extremity, we find that there are cer- 
tain small veins belonging to the superficial system. Those 
which have received distinctive names are two in number, the 
short and the long saphenous. They commence on the dorsal 
aspect of the foot, the long saphenous on the inner and the short 
saphenous on the outer side; and the veinlets which compose 
them inosculate with one another so as to form an arch, ex- 
tending entirely across the foot near the web of the toes. 
Short Saphenous. 
The short saphenous (saphena parva) vein can be traced 
back from the outer edge of the little toe behind the external 
malleolus, where it passes to the postero-external aspect of the 
leg, accompanying the nerve of the same name. As it passes 
upward, it gradually winds to the middle of the calf of the 
leg, and there lies in the groove which is found on the posterior 
face of the gastrocnemius muscle. It continues its upward 
course between the two heads of the gastrocnemius, and ter- 
minates by emptying into the popliteal vein. 408 
DESCRIPTIVE ANATOMY. 
Long Saphenous. 
The LONG saphenous (saphena magna) vein commences on 
the inner side of the great toe. It passes backward along the 
inner side of the arch of the foot, runs across the front of the 
internal malleolus, passes upward on the inner face of the calf, 
behind the internal condyle of the femur, until it reaches the 
junction of the lower third with the middle third of the thigh, 
where it runs slightly forward, and continues its upward course 
along the inner front aspect of the thigh until it reaches the 
saphenous opening in the fascia lata, where it pierces the cribri- 
form fascia, and terminates by emptying into the femoral vein. 
Occasionally before emptying into the femoral the long saphe- 
nous receives the satellite veins of the superficial branches of 
the femoral artery; and more frequently these branches, four 
in number, terminate by opening directly into the femoral vein, 
the apertures which they make through the fascia covering the 
saphenous opening giving it its cribriform appearance. Through- 
out its course it receives tributaries from veins on the inner, 
outer and front aspects of the leg and thigh. 
The Veins of the Upper Extremity. 
The veins OF THE upper extremity, like those of the lower, 
consist of a superficial and a deep set; but unlike the lower 
extremity, the superficial veins are here so large and so numer- 
ous that the satellite veins are small in size, and convey but a 
small portion of the return circulation. 
The deep veins commence in the palm of the hand. They com- 
mence as the companion veins of the superficial palmar arch, 
originating in veins which accompany the digital branches of 
that arch. This arch receives the interosseous veins; and forms 
on either side the venae comites of the ulnar and radial arteries. 
The companion veins of the radial and ulnar arteries unite 
with each other below the bend of the elbow, and form the two 
satellite veins of the brachial artery. That is, the satellite 
veins of the radial form the external satellite vein of the bra- 
chial, while the satellite veins of the ulnar form the internal THE VENOUS SYSTEM. 
409 
satellite vein of the same artery. After receiving superficial 
veins and tributaries from the branches of the brachial, these 
two satellites pass upward to the lower border of the tendons 
of the latissimus dorsi and teres major muscles, and there unite 
to form the axillary vein, which, after receiving the basilic, fol- 
lows the course of the axillary artery, lying to its inner front 
aspect throughout the course of that vessel, receiving tribu- 
taries from the veins accompanying branches of that vessel, the 
largest and most important of which are the companion veins 
of the subscapular artery, and terminates at the outer border 
of the first rib by becoming the subclavian vein. This vein, 
then, after receiving the cephalic, continues its course to join 
the internal jugular, and form the innominate vein. 
The Superficial Veins of the Upper Extremity. 
Anterior Ulnar. 
Posterior Ulnar. 
Radial. 
Median. 
Common Ulnar. 
Basilic. 
Cephalic. 
Median Basilic. 
Median Cephalic. 
The Anterior Ulnar. 
The ANTERIOR ULNAR vein begins on the inner front aspect of 
the ulnar side of the hand by small tributaries which come 
from the little finger and inner side of the ring and middle 
fingers. Continuing its course upward it receives tributaries 
from adjacent portions of the forearm; and about an inch and 
one-half below the elbow-joint, unites with the posterior ulnar 
to form the common ulnar vein. 
The Posterior Ulnar. 
The posterior ULNAR vein arises near the back of the little 
finger, passes upward on the postero-internal aspect of the 
forearm; and joins the anterior ulnar to form the common ulnar. 410 
DESCRIPTIVE ANATOMY. 
The Common Ulnar. 
The COMMON ULNAR vein ascends to the inner side of the 
front of the elbow to unite with the median basilic vein, a little 
above the elbow, to form the basilic vein. 
The Radial Vein. 
The RADIAL vein commences on the outer side of the back of 
the hand, receiving tributaries from the thumb, index and 
middle fingers; and passing upward, winds around to the front 
of the forearm about at its lower third. It then continues to 
ascend until it reaches a point about an inch above the elbow 
joint, where it unites with the median cephalic to form the 
cephalic vein. 
The Median Vein. 
The median is a small vessel which receives the blood from 
the middle of the palm of the hand. It is scarcely perceptible 
until just above the wrist joint, where the formation of the 
vein may be said to take place. It then passes directly up- 
ward, lying on the middle of the front of the forearm until it 
reaches a point about an inch and a half below the middle of the 
front of the elbow-joint. In this situation it divides into two 
branches, an internal and an external, named respectively the 
median basilic and the median cephalic. 
The Median Basilic. 
The MEDIAN basilic vein unites with the common ulnar, the 
product of the anterior and posterior ulnar veins, to form the 
basilic. 
The Median Cephalic. 
The MEDIAN CEPHALIC vein unites with the radial vein to form 
the cephalic vein. THE VENOUS SYSTEM. 
411 
The Basilic Vein. 
The BASILIC vein, formed above the elbow-joint by the union 
of the common ulnar with the median basilic, passes upward 
and crosses over the bicipital slip of fascia given off from the 
tendon of the biceps to the fascia of the inner side of the fore- 
arm. It then lies to the inner front aspect of the brachial 
artery to about the middle of the course of that vessel, separated 
from it by the deep fascia, where its relation is changed only 
to the extent of lying beneath the investing fascia. That is, 
up to the middle of the brachial artery the basilic vein is super- 
ficial to the investing fascia; but opposite the middle of that 
vessel it pierces this fascia, and becomes deeper-lying still 
to the inner front aspect of the brachial artery, but more nearly 
on the same plane with that vessel. It finally terminates by 
uniting with the internal satellite vein of the brachial just be- 
fore the latter unites with the external satellite to form the 
axillary vein. Some authorities describe the basilic as receiv- 
ing the two satellite veins of the brachial and becoming the 
axillary vein. 
The Cephalic Vein. 
The CEPHALIC vein, formed above the elbow-joint by the union 
of the radial and the median cephalic, passes upward and out- 
ward in the interval between the brachialis anticus and the 
supinator longus and extensor carpi radialis longior. It then 
passes upward in a groove found on the outer aspect of the 
arm, caused by the bulging of the biceps anteriorly and the 
triceps posteriorly; and continues its course until it reaches 
the lower edge of the deltoid muscle, when it turns across the 
front of the arm to reach the interval between the deltoid and 
the pectoralis major. After running in the groove between 
these two muscles, it passes over the fibrous-covered interval be- 
tween the muscles and empties into the axillary vein just before 
its termination in the subclavian. Before the cephalic vein 
enters the axillary it receives a communication from the ex- 
ternal jugular vein of the neck. 412 
DESCRIPTIVE ANATOMY. 
The Axillary Vein. 
The axillary vein is formed by the junction of the brachial 
satellites and the basilic at the termination of the axillary 
artery. It passes upward on the inner front aspect of the axil- 
lary artery through the axillary space, receives the tributaries 
which accompany the branches of that vessel, and the cephalic, 
and continually increases in size until it reaches the outer bor- 
der of the first rib behind the junction of the outer third with 
the inner two-thirds of the shaft of the clavicle, where it ter- 
minates by becoming the subclavian vein. 
The Subclavian Vein. 
The subclavian vein bears the same relation to its artery 
that the string bears to a bent bow. Commencing at the outer 
one-third of the clavicle on the anterior border of the first rib, 
it passes horizontally inward, lying below and on a plane an- 
terior to the corresponding artery, so that it is an antero-in- 
ternal relation of the third portion of the subclavian, and an 
antero-external relation of the first portion of the subclavian, 
being separated from the second portion by the interposition 
of the scalenus anticus muscle. As this vein passes inward, 
it receives, first, the companion veins of the supra-scapular and 
transversa colli arteries. These veins usually unite before en- 
tering the subclavian, but occasionally enter by separate open- 
ings. The external jugular vein, which sends a branch to the 
cephalic, also empties into the subclavian. The manner of its 
entrance will be described later. The subclavian then receives 
the companion branches from the thyroid axis, though the in- 
ferior thyroid empties into the innominate and vertebral ar- 
teries, and terminates behind the sterno-clavicular articulation 
by uniting with the internal jugular to form one of the innomi- 
nate veins. 
The Veins of the Head and Neck. 
The VEINS OF the head consist of a set of channels found in 
the cranium, formed by divisions in the dura mater, and called THE VENOUS SYSTEM. 
413 
"sinuses," while the veins of the neck are described under the 
name of "jugular" veins (L. jugulum-diminutive of jugum, 
the yoke-the throat), of which, however, there are three: the 
internal, external, and anterior jugular. In addition to these 
jugular veins there are smaller veins, such as the thyroid and 
the vertebral, which, during a portion of their course, are 
found lying in the neck. Certain veins are also found upon the 
face, which aid in forming the jugulars. 
The Veins of the Diploe. 
Ramifying between the tables of the bones of the skull are 
numerous veins called diploetic. They take the name of the 
region they occupy and finally converge to form trunks which 
open either into the sinuses of the interior or the veins of the 
exterior. Connecting the sinuses of the interior with the veins 
of the exterior of the head are several veins called emissary, 
which pass through foramina such as the mastoid and parietal. 
The Sinuses of the Dura Mater. 
Superior Longitudinal. 
Inferior Longitudinal. 
Straight. 
Lateral. 
Cavernous. 
Superior Petrosal. 
Occipital. 
Inferior Petrosal. 
These sinuses are formed by the union of veins found in two 
positions in the cranium: one set called the veins of the diploe, 
lying between the two tables of which the bones of the skull are 
composed, while the other set, the cerebral veins, are found 
ramifying over the surface and in the interior of the encepha- 
lon. The cerebral veins consist of two sets, superficial and 
deep. The superficial lie upon the surface of the brain, while 
the deep cerebral veins lie in the ventricular cavities of the 
brain, ultimately uniting to form two ventricular veins, the 
venae Galeni, which leave the interior of the brain through the 
great transverse fissure and terminate in the straight sinus. 
The upper superficial veins empty into the superior longi- 414 
DESCRIPTIVE ANATOMY. 
tudinal sinus; the largest of the lower into the cavernous, while 
others empty into the petrosal and lateral sinuses. 
The Superior Longitudinal Sinus. 
The superior longitudinal sinus (s. saggitalis superior) 
commences at the foramen caecum, where it communicates with 
the small veins of the nasal fossa. The groove along which 
it runs may be discovered on the dried bones as occupying the 
mid-line of the frontal bone, and grooving equally the upper 
border of the two parietal bones. Leaving these bones, it ap- 
pears on the occipital, grooves it in the mid-line, and passes 
backward to the torcular Herophili by the side of the anterior 
occipital protuberance, to diverge on one or the other side into 
one of the lateral sinuses. This sinus, like other sinuses of the 
dura mater, is not strictly speaking a vein; it is the space be- 
tween two layers of the dura; and its resemblance to a vein 
consists only in two facts; viz., that it conveys venous blood, 
and that it is lined internally by the endothelial coat, which all 
blood vessels contain. As it passes along the groove, this sinus 
receives the superficial cerebral veins. 
The Inferior Longitudinal Sinus. 
The INFERIOR LONGITUDINAL sinus (s. saggitalis inferior) is 
a small sinus, circular on cross-section (unlike the superior, 
which is triangular on cross-section). It commences near the 
anterior extremity of the falx major, follows the curvature of 
that subdivision of the dura mater, and passes backward to 
the junction of the falx major with the tentorium cerebelli, 
where it empties into the straight sinus. 
The Straight Sinus. 
The straight SINUS (s. tentorii or s. rectus) runs in the trian- 
gular interval between the falx major and the tentorium, to ter- 
minate in one of the lateral sinuses. Before receiving the in- THE VENOUS SYSTEM. 
415 
ferior longitudinal sinus, the straight sinus first receives the 
venae Galeni, coming from the ventricles of the brain. 
The Occipital Sinus. 
The occipital sinus is the smallest of the cranial sinuses; it 
commences by several small veins around the foramen magnum, 
and is situated in the attached margin of the falx cerebelli, com- 
municating with the posterior spinal vein, and finally emptying 
into the torcular Herophili. 
The Cavernous Sinuses. 
The cavernous sinuses are found on the lateral aspect of 
the body of the sphenoid. They commence in front by receiving 
the ophthalmic veins from the sphenoidal fissure. The ophthal- 
mic veins, following the course of the ophthalmic artery, pass 
over the sphenoidal fissure, and empty into the cavernous 
sinuses. These, in turn, winding along the lateral aspect of the 
body of the sphenoid, pass to the junction of that bone with 
the petrous portion of the temporal, and there join with the 
petrosal sinuses. Stretching across between the cavernous 
sinuses are two small transverse vessels, which surround the 
pituitary body, one in front and the other behind. These to- 
gether form the circular sinus. 
After the cavernous sinuses have received the superior 
petrosal and emptied into the inferior petrosal sinus on the side 
of the basilar process of the occipital bone, they are united by 
a small vein, extending between the two, which is called the 
transverse sinus. 
The Superior Petrosal Sinus. 
The superior petrosal sinus is situated on the upper border 
of the petrous portion of the temporal. Its inner extremity 
is connected with the cavernous sinus, while its outer is con- 
nected with the lateral sinus, just as that sinus reaches the 
inner face of the mastoid portion of the temporal, and receives 
the mastoid veins. 416 
DESCRIPTIVE ANATOMY. 
The Inferior Petrosal Sinus. 
The inferior petrosal SINUS occupies the groove between 
the posterior border of the petrous portion of the temporal and 
the inner half of the lower border of the occipital. It receives 
the cavernous sinus in front; and terminates behind by uniting 
with the lateral sinus. 
The Lateral Sinuses. 
The LATERAL SINUSES commence at the torcular Herophili, 
where the longitudinal sinus empties. The torcular is never 
situated on the mid-line of the body; but to one or the other 
side, more frequently to the right. The blood from the superior 
longitudinal sinus pours into the lateral sinus, usually of the 
right side, while the current of blood from the occipital and 
straight sinuses usually passes into the opposite lateral sinus. 
The lateral sinus of each side arches outward along the an- 
terior face of the occipital bone; but leaves that bone to appear 
momentarily on the postero-inferior angle of the parietal. Leav- 
ing the parietal, it passes downward and inward in a curved 
direction across the internal face of the mastoid portion of the 
temporal, forming a deep depression in this bone, the fossa sig- 
moidea and finally at the posterior extremity of the jugular 
foramen (the foramen lacerum posterius), unites with the in- 
ferior petrosal sinus to form the internal jugular vein. 
It will be seen, therefore, that the right internal jugular 
conveys the blood received from the superior longitudinal sinus, 
which, in its turn, receives the superficial cerebral veins, while 
the left internal jugular conveys most of the blood carried by the 
venae Galeni, and from this by the straight sinus, into the left 
lateral sinus. The veins of the base of the brain are about equally 
distributed by means of the petrosal, transverse and circular 
sinuses into the corresponding jugular veins. 
It must never be forgotten that the veins of the diploe com- 
municate with the sinuses of the dura mater on the one hand, 
while on the other they communicate with the superficial veins 
of the cranium. These communicating veins are described as THE VENOUS SYSTEM. 
417 
emissary veins, so that any infection of the tissues occupying 
the surface of the skull may readily pass along the course of the 
emissary veins into the interior of the skull, and so establish 
an inflammation of the brain itself. 
The Internal Jugular. 
The INTERNAL JUGULAR vein, formed, as above described, by 
the union of the inferior petrosal with the lateral sinus, is a 
largely diluted aperture at the base of the cranium; but it 
quickly contracts to about twice the size of the internal carotid 
artery. At its origin it lies immediately behind the internal 
carotid artery, with the twelfth, or hypo-glossal, nerve behind 
and slightly internal to it, and the ninth, tenth and eleventh 
cranial nerves emerging in the interval between itself and the 
internal carotid. It then passes downward as an external rela- 
tion of the internal carotid to the point at which that vessel 
is derived from the common carotid artery; then becomes an 
external relation of the common carotid artery, and maintains 
that relation to the origin of that vessel behind the sterno- 
clavicular articulation, where it terminates by joining the sub- 
clavian vein to form the innominate vein of that side. In its 
course down the neck, the glosso-pharyngeal and hypo-glossal 
nerve pass forward between the artery and the vein, cross the 
front of the artery and cease to be relations of the vein. The 
eleventh, or spinal accessory, nerve passes behind the vein near 
the upper portion of its course; but the tenth continues an in- 
ternal relation of the internal jugular throughout the entire 
course of that vein. 
Its tributaries are the facial, lingual, pharyngeal, superior 
and middle thyroid veins. 
The External Jugular. 
The external JUGULAR vein, commencing in the substance 
of the parotid gland by the union of the posterior auricular and 
the posterior branch of the temporo-maxillary, receiving the 
greater portion of the blood from the exterior of the cranium 418 
DESCRIPTIVE ANATOMY. 
and the deep parts of the face, runs down the neck in the direc- 
tion of the fibres of the platysma myoides muscle, which covers 
it. It runs nearly parallel with the posterior border of the 
sterno-cleido-mastoid muscle until it reaches a point just above 
the clavicle, where it changes its direction, and passing down- 
ward and inward, empties into the subclavian vein. 
The Anterior Jugular. 
The anterior jugular (occasionally only one) commences 
near the hyoid bone, passes downward near the anterior border 
of the sterno-mastoid and about an inch above the clavicle, 
after communicating with the vein of the opposite side, the in- 
ferior thyroid and internal jugular, empties into the external 
jugular, as a rule, though, sometimes into the subclavian. It 
crosses the first part of the common carotid and passes under 
the sterno-cleido-mastoid. 
The Vertebral Veins. 
The vertebral veins commence by tributaries at the upper 
part of the back of the neck, pass downward in the foramina 
of the transverse processes, which transmit the vertebral artery; 
and the two satellites, one passing through the sixth and the 
other through the seventh transverse process, to form a single 
vein, which empties into the innominate vein of the correspond- 
ing side. 
The Veins of the Face. 
The VEINS OF the FACE consist of numerous branches, which 
correspond to the arteries of the face. Of these, the supra- 
orbital commencing1 on the forehead, communicates with the 
temporal vein, and joins the frontal to form the facial vein. 
This, after receiving the nasal, superior labial, transverse facial, 
and inferior labial, passes over the lower border of the jaw, 
about an inch in front of the angle, or opposite the internal 
border of the masseter muscle, receives a communication from 
the temporo-maxillary vein, and, at the level of the hyoid bone, THE VENOUS SYSTEM. 
419 
after crossing the external carotid, empties into the internal 
jugular. 
The Temporal Veins. 
The temporal veins commence on the lateral aspect of the 
skull by numerous tributaries, pass downward in an interval 
between the external auditory meatus and the tempero-maxillary 
articulation, run into the substance of the parotid gland, and 
receive the internal maxillary vein, made up of tributaries ac- 
companying branches of the internal maxillary artery, and be- 
hind the neck of the condyle of the lower jaw forms the tempero- 
maxillary vein. 
This vein divides into two branches, one of which has been 
already alluded to as uniting with the facial vein to empty into 
the internal jugular, while the other unites with the posterior 
auricular to become the external jugular vein. 
The Innominate Veins. 
The INNOMINATE veins of the two sides differ in direction, 
though but little in formation. 
On the right side the innominate vein has already been de- 
scribed as formed behind the right sterno-clavicular articulation 
by the union of the subclavian and internal jugular veins. On 
the left side the vein is formed in the same way; but usually 
the internal jugular lies to the inner front aspect of the left 
subclavian artery, instead of crossing directly over the front 
as is the case on the right side. 
The innominate vein on the right passes downward and in- 
ward, parallel with the anterior to the innominate artery, and 
a little to the right side of that vessel. On the left, the in- 
nominate vein, also called the great transverse vein of the neck, 
crosses successively the thoracic portions of the left subclavian 
and left common carotid arteries and the arteria innominata, 
and lying above and on a plane anterior to the transverse aorta. 
At the right side of the commencement of the transverse aorta 
two innominate veins unite to form the superior vena cava. 420 
DESCRIPTIVE ANATOMY. 
The Superior Vena Cava. 
The SUPERIOR VENA CAVA descends anterior and external to the 
ascending aorta, pierces the fibres of the pericardium, and 
enters the venous, or right, auricle of the heart on the upper 
posterior aspect of that organ. 
Besides these veins there are several smaller veins which are 
found mainly in the thoracic cavity and lower portion of the 
neck. 
Of these, the satellite veins of the internal mammary artery 
empty into the corresponding innominate vein. 
The inferior thyroid veins pass likewise into the correspond- 
ing innominate veins. 
The superior intercostal veins, returning the blood from the 
upper intercostal spaces, except the first, empty, the right oner 
into the vena azygos major, the left usually into the left in- 
nominate vein. 
The azygos veins connect the superior and inferior venae 
cavae. They are three in number, vena azygos major, vena 
azygos minor and vena azygos minor inferior. 
The Vena Azygos Major. 
The AZYGOS major commences in the abdominal cavity op- 
posite the first or second lumbar vertebra, sometimes from the 
first lumbar vein, sometimes by a branch from the renal vein. 
It enters the thorax through the aortic opening of the diaph- 
ragm; and receiving branches from the lower six intercostal 
spaces, finally terminates by crossing the vertebral column op- 
posite the fourth dorsal vertebra behind the thoracic aorta, 
and empties into the superior vena cava just before that vessel 
passes into the heart. 
The Vena Azygos Minor Inferior. 
Just before the azygos major crosses the vertebral column it 
is joined by the vena azygos MINOR, which conveys the blood 
from the intercostal spaces below the seventh. It enters the THE VENOUS SYSTEM. 
421 
thorax through the left crus of the diaphragm. At its lower 
extremity this vessel frequently communicates with the inferior 
vena cava, and thus directly establishes a communication be- 
tween the superior and inferior venae cavae. Occasionally, how- 
ever, the communication consists entirely of a branch from the 
renal vein, which in its turn empties into the inferior vena cava, 
and thus indirectly establishes this communication. 
The Vena Azygos Minor Superior. 
The vena azygos minor superior is usually formed by the 
left fourth, fifth, sixth and seventh intercostals. It empties 
usually into the azygos major, and sometimes into the minor. 
The Spinal Veins. 
The spinal veins consist of three sets, as follows: 
Dorsal Spinal Veins. 
The dorsal spinal veins are numerous veins forming a net- 
work on the exterior of the vertebrae. 
Meningo-Rachidian Veins. 
The meningo-rachidian are four veins perpendicular in di- 
rection, which lie within the spinal canal between the bone and 
dura mater, two in front and two behind. 
Medulli-Spinal Veins. 
The medulli-spinal are numerous veins ramifying beneath 
the arachnoid membrane of the spinal cord. 
The Cardiac Veins. 
The veins of the heart are two, as follows: 422 
descriptive anatomy. 
The Great Cardiac Vein. 
The great cardiac vein ascends in the anterior ventricular 
groove, winds around the left auriculo-ventricular groove and 
opens into the right auricle. The last inch of its course is known 
as the coronary sinus. 
The Posterior Cardiac Vein. 
The posterior cardiac vein is small and ascends in the pos- 
terior ventricular groove to open into the great cardiac vein. 
The Pulmonary Veins. 
These veins convey arterial blood and are formed in the lung 
substance by direct communication with the terminals of the 
pulmonary arteries. Usually there are two from each lung; but 
sometimes the two left veins unite before emptying into the 
left auricle, and now and then, the middle right fails to unite 
with the upper right, and then there are three opening from 
the right side. 
THE LYMPHATIC SYSTEM. 
The lymphatic SYSTEM consists of numerous small vessels 
ramifying in nearly every tissue of the body, and of small, 
reddish, pea-like bodies called lymphatic glands, found at in- 
tervals along the lymphatic vessels. The lymphatic vessels are 
intended for the most part to remove from the tissues the detritus 
of assimilation, consisting mainly of unexpended plasma; con- 
sequently the course of their circulation is from the periphery 
towards the centre, and in their route they will be found to 
accompany the veins. 
Wherever they are found the lymphatics consist of two sets, 
superficial and deep. In the extremities the superficial set is 
found just beneath the skin; the deep in and among the muscles. 
In the viscera the superficial set ramifies on the surface, while 
the deep is found in the structure. The greater portion of the 
lymphatics of the body converge to form one large vessel, the THE LYMPHATIC SYSTEM. 
423 
thoracic duct, which empties into the venous current near the 
heart. 
Thoracic Duct. 
The thoracic duct begins on the front of the body of the 
second lumbar vertebra by a considerable dilation called recepta- 
culum chyli, which, narrowing to a tube the size of a goose quill, 
ascends the front of the vertebral column behind the descending 
aorta, passes through the aortic opening of the diaphragm and 
continues upward as high as the fourth dorsal vertebra, where 
it inclines to the left and continues thence an oblique ascent be- 
hind the arch of the aorta to a point on a level with the seventh 
cervical vertebra, where it arches forward and downward and 
opens into the commencement of the left vena innominata. Just 
before its termination it receives the lymphatics of the head, 
neck and upper extremity of the left side. Opening into the 
commencement of the right vena innominata is another and 
much smaller lymphatic duct (ductus lymphaticus dexter) which 
conveys lymph furnished it by the right upper extremity and 
right side of the head and neck. 
Lymphatics of the Lower Extremity. 
The superficial lymphatics of the lower extremity are 
found crowding upward in immense numbers along the course 
of the saphenous veins and, reaching the saphenous opening in 
the fascia lata, where the vein terminates near Poupart's liga- 
ment, they then pass through a set of lymphatic glands. The 
deep lymphatic vessels accompany the deep veins upward to 
the groin, where they are connected with a set of glands, lying 
beneath the fascia lata and superficial muscles, called the deep 
lymphatic glands of the groin. Along the course of these ves- 
sels are found a few glands, some in the popliteal space and one 
on the front of the interosseus membrane of the leg. The lym- 
phatic vessels from the external organs of generation and from 
the abdominal parietes can be traced to a third set of glands, 
which form a chain along Poupart's ligament, lying superficial 
and above the glands around the saphenous opening. 424 
DESCRIPTIVE ANATOMY. 
All these vessels pass beneath Poupart's ligament to become 
the external iliac lymphatics which accompany the external iliac 
vessels and unite with the internal iliac lymphatics to form the 
common iliac lymphatics, which accompany the common iliac 
vessels and unite with those of the opposite side to form the 
lumbar lymphatics. Scattered at intervals along these vessels 
from Poupart's ligament are lymphatic glands. The lumbar 
lymphatics ascend along the aorta, constantly increasing in size 
by accessions from the abdominal viscera, and having passed 
through numerous glands, and lessened in number as they in- 
creased in size, they eventually open into the receptaculum chyli, 
which is so named from the fact that the lymphatics which 
it receives from the small intestine are, during the process of 
digestion, filled with chyle. 
The Lymphatics of the Upper Extremity. 
The lymphatics of the upper extremity, like those of the 
lower, consist of a superficial and a deep set. The superficial 
ascend in company with the superficial veins and the deep ac- 
company the deep veins, both converging to the arm pit where 
there are some twelve or fifteen lymphatic glands. Besides the 
vessels from the upper extremity these glands also receive those 
from the chest wall and mammary gland. A few glands are 
found along the course of the lymphatics before they reach the 
axilla, some at the elbow and some along the brachial vessels; 
these, however, are small and unimportant. From the axillary 
glands the vessels proceed along the course of the subclavian 
vein, opening on the left side into the termination of the thoracic 
duct and on the right into the ductus lymphaticus dexter. 
Lymphatics of the Head and Neck. 
The LYMPHATICS OF THE HEAD AND NECK consist of vessels 
which have come from the exterior of the head and others 
which have converged from veins supplying the internal and 
external jugular veins, no lymphatics, however, being found in 
the substance of the brain. THE CENTRAL NERVOUS SYSTEM. 
425 
These vessels descend along the external, and especially the 
internal, jugular veins and on the right side open into the ductus 
lymphaticus dexter while on the left side they join the thoracic 
duct. 
The Lymphatics of the Thorax. 
The lymphatics accompanying the intercostal vessels open 
into the thoracic duct. Those from the right lung, a portion 
of the thoracic parietes, diaphragm and even a portion of the 
upper surface of the liver and the short border of the heart 
seek the ductus lymphaticus dexter; while those from the left 
lung, left side of the thorax and most of the heart join the 
thoracic duct. The vessels from the lungs pass through a set of 
glands situated around the bifurcation of the trachea called 
the bronchial glands. 
THE CENTRAL NERVOUS SYSTEM. 
Cerebro-Spinal Centres. 
The chain of nervous centres known as the cerebro-spinal 
axis is divided into two portions, one contained in the spinal 
canal, and called the spinal cord, or medulla spinalis (L. medius, 
middle), the other contained in the cranium and called the brain, 
or encephalon. Enveloping each of these portions and lining its 
containing cavity are three membranes, lying one within the 
other, called the investing membranes, or meninges. 
The Membranes of the Brain. 
The membranes OF the brain are the dura mater (L. hard 
mother), lying next to the cranial wall; the pia mater (L. deli- 
cate mother), lying next to the brain; and the arachnoid be- 
tween the two. 
The Dura Mater 
The dura mater is a grayish white, strong, fibrous membrane 
which lines the inner surface of the cranial wall, adhering DESCRIPTIVE ANATOMY. 
426 
closely to the bone, and supplying the place of an internal perios- 
teum. Its internal surface is glistening and smooth lined by an 
endothelial layer, which performs the functions of a serous mem- 
brane. Besides lining the interior of the cranial cavity, the 
dura mater gives off septa, which passing between the different 
portions of the brain, serve to separate them from one another 
and to support the brain in its position, besides carrying blood- 
vessels which receive and return the circulation from the in- 
terior of the cavity. These processes are four in number: the 
falx major, or falx cerebri, the tentorium cerebelli, the falx 
minor, or falx cerebelli, and the diaphragmae sellae. 
The falx major (L. falx, a scythe), or falx cerebri, is a sickle- 
shaped process which lies in the great longitudinal fissure of 
the brain. It is attached in front to the crista galli and extends 
along the mid-line to the anterior occipital protuberance, and is 
attached to the superior surface of the tentorium along its mid- 
dle line. Along its attachment to the cranium, the falx major 
divides into two layers, which are attached to the margins of 
the groove found on the frontal, parietal, and occipital bones. 
Between these two layers is a triangular space, which lodges one 
of the important sinuses, the superior longitudinal sinus. The 
concave lower margin is hollowed out into a small canal, circu- 
lar on cross section, which extends from the foramen caecum 
to the attachment of the falx major to the tentorium. This is 
called the inferior longitudinal sinus. 
The tentorium (L. tendere, to stretch) commences at the pos- 
terior occipital protuberance, and passing transversely forward, 
extends into the great transverse fissure of Bichat separating 
the cerebrum from the cerebellum serving to support the pos- 
terior lobes of the cerebrum and at the same time to bind the 
cerebellum in the cerebellar fossae. Along its upper surface from 
before backwards is attached the posterior extremity of the falx 
major. Its posterior border, divided like the falx major into 
two layers, is attached along the margin of the lateral limbs of 
the occipital cross; and leaving this bone, passes forward on 
the superior border of the petrous portion of the temporal bone, 
at the apex of which it is joined by the concave free anterior 
border. This anterior border presents a horseshoe-shaped ap- THE CENTRAL NERVOUS SYSTEM. 
427 
pearance, and when the two borders, anterior and posterior, meet 
with one another, they cross, so that the free border continues 
forward to be attached to the anterior clinoid process, while 
the attached border reaches the posterior clinoid process. Be- 
tween these attachments is left an opening through which is 
transmitted the midbrain. At the attachment of the posterior 
border is a sinus, a continuation of the great longitudinal sinus 
on one side, forming the lateral sinus. Where the tentorium is 
attached to the upper border of the petrous portion of the tem- 
poral is another sinus, the superior petrosal; and where the 
falx major is attached on the superior surface of the tentorium 
is found a third sinus, the straight sinus passing backward to 
the torcular Herophili. 
The falx cerebelli is a small narrow process of the dura, which 
extends from the margin of the foramen magnum upward to 
the under surface of the tentorium to the posterior part of 
which it is attached, at the anterior occipital protuberance. It 
projects between the two lobes of the cerebellum, and serves to 
separate them from one another. 
The diaphragmae sellae is the small fold which roofs in the 
sella turcico. 
The Arachnoid. 
The arachnoid is a delicate membrane enveloping the brain 
between the dura and pia and separated from the latter by a 
space (the subarachnoidean) filled with cerebro-spinal fluid. It 
does not dip into the sulci of the brain; but leaps from convolu- 
tion to convolution, so that a space is interposed at various por- 
tions of the brain between the arachnoid and the pia mater. It 
can be easily demonstrated at some portions of the brain, while 
at others it is scarcely perceptible. On the inferior surface of 
the brain, stretching between the two peduncles of the cerebrum, 
and covering the inter-peduncular space, a considerable distance 
exists between the pia and the arachnoid; and again in the great 
transverse fissure of Bichat the space can be easily made ap- 
parent. DESCRIPTIVE ANATOMY. 
428 
The Pia Mater. 
The PIA MATER is an extremely thin and very vascular mem- 
brane, consisting almost entirely of small interlacing blood ves- 
sels, held together by layers of connective tissue. It covers the 
entire surface of the brain; and not only does this, but dips into 
every sulcus and every depression of the brain. Thus, it passes 
through the great transverse fissure of Bichat, covering not only 
the cerebellum and the under surface of the cerebrum; but con- 
tinuing through this fissure, it passes even into the interior of 
the brain itself, so that prolongations of the pia are found in 
the ventricles, in the interior of the hemispheres, and connect- 
ing with the blood vessels which perforate from the base of the 
brain and supply the structures in the interior of each hemis- 
phere. It serves also in one portion of the brain to form the 
roof of one of the ventricles. An examination of the brain with 
its frequent elevations and depressions forming the convolu- 
tions and sulci would show that if this membrane were stripped 
off, its area would be enormously greater than the apparent 
area of the brain itself. Every sulcus into which the membrane 
dips forms a corresponding fold, so that it bears a close re- 
semblance in its folds to a dress or other garment which has 
been taken out of a trunk. 
The Brain. 
The brain, or encephalon, was formerly divided into the 
cerebrum, cerebellum, pons Varolii and the medulla oblongata. 
Recent observations of the development of the cerebral vesicle 
have shown that this subdivision was too simple and inaccurate 
to suit the scientific mind, and many efforts have been made to 
find a satisfactory nomenclature for the brain. 
The cerebral vesicle is constricted at two points, thus forming 
three vesicles. These develop and ultimately divide, so that 
from their division we get a scientific reason for speaking of 
the fore, mid and hind-brain. The fore-brain (prosencephalon) 
is the product of the first cerebral vesicle. The anterior part 
(telencephalon) expands to form the lateral ventricles and the THE CENTRAL NERVOUS SYSTEM. 
429 
surrounding parts of the hemispheres and commissures; while 
the posterior part (diencephalon), forms the third ventricle and 
its surrounding walls. 
The mesencephalon, or mid-brain-developed from the middle 
cerebral vesicle-is made up of the corpora quadrigemina, aque- 
duct of Sylvius and the crura cerebri. 
The hind-brain, or rhombencephalon-from the posterior 
cerebral vesicle, includes the medulla oblongata the fourth ven- 
tricle, the pons, and the cerebellum. 
The weight of the entire brain varies with the period of life, 
with the sex of the individual, with the cause of death, the 
period after death, at which the weight is taken, and with 
various other circumstances. The average weight is about 
forty-eight ounces for the male, and about forty-four or forty- 
five for the female adult. The intellectuality of the individual 
bears scarcely any relation to the weight of the brain, some of 
the heaviest brains having been those of people by no means 
distinguished for ability, while comparatively small brains have 
been found in people of a high order of intelligence. The intel- 
lectuality varies more with the variety and number of the 
convolutions, and consequently with the amount of "gray mat- 
ter," than it does with the actual bulk of the brain. 
The cerebrum is seven or eight times the size of the rest of 
the brain, presenting an uneven, convoluted surface. When 
closely examined these convolutions are seen to be dissimilar on 
the two sides of the brain, nor do we ever find any two brains 
with precisely the same convolutions. Certain depressions which 
separate these convolutions from one another, from the fact 
that they appear at an early stage of foetal life, are called "pri- 
mary fissures," and from these primary fissures we get the great 
subdivisions of the cerebrum. These primary fissures are the 
great longitudinal fissure, the great transverse fissure of Bichat, 
the fissure of Sylvius, the fissure of Rolando, and the parieto-oc- 
cipital fissure. The great longitudinal fissure serves to separate 
the two hemispheres of the cerebrum; the transverse fissure of 
Bichat to separate the cerebrum from the cerebellum; the fissure 
of Sylvius to separate the frontal from the temporo-sphenoidal, 
and by its horizontal limb, the parietal from the temporo- 430 
DESCRIPTIVE ANATOMY. 
sphenoidal; the fissure of Rolando to separate the frontal from 
the parietal; while the parieto-occipital of course separates the 
parietal and occipital lobes. 
The Convolutions of the Cerebrum. 
In studying the convolutions of the cerebrum we begin with 
the five principal, or primary, fissures. 
The great longitudinal fissure commences on the base of the 
brain, extends upward between the two hemispheres, turns 
backward toward the posterior extremity, and cutting between 
the two hemispheres behind, separates them from one another. 
It will, therefore, be seen that the two hemispheres of the cere- 
brum are united in the middle, but are separated in front and 
behind. The bond of union between them, the corpus callosum, 
extends further in front than behind, and is thicker behind than 
in front. 
The fissure of Sylvius (lateral cerebral fissure). Com- 
mencing on the base of the brain near the great longitudinal 
fissure, or, more correctly, at the anterior perforated spot, is 
the fissure of Sylvius. It is first directed outward, forming a 
means of separation between the frontal and temporo-sphenoidal 
lobes. On leaving the base of the brain to appear on the outer 
surface of the hemisphere it changes its direction and passes 
upward and backward, forming what is called the horizontal 
limb of the fissure of Sylvius, which separates the temporo- 
sphenoidal below from the parietal above. The horizontal limb 
of the fissure of Sylvius extends backward as far as the com- 
mencement of the occipital lobe, or the junction of about the 
posterior one-fifth with the anterior four-fifths of the cerebrum. 
Just as the main fissure reaches the outer surface of the hemis- 
phere, the vertical limb is given off, which ascends in the con- 
volutions of the frontal lobe, forming in this situation an over- 
hanging appearance, which is described as the operculum (L. 
operire, to cover.) 
The fissure of Rolando, or central sulcus, is situated about the 
middle of the outer surface of either hemisphere. It begins near 
the longitudinal fissure and runs first downward and forward THE CENTRAL NERVOUS SYSTEM. 
431 
about two-thirds of its course. It then makes an abrupt knee- 
like bend; and passing nearly vertically downward, terminates 
near the division of the fissure of Sylvius into its two limbs. 
The parieto-occipital fissure is but slightly seen on the outer 
surface of the hemisphere, the main portion of the fissure lying 
on the inner face. It commences beneath the gyrus fornicatus 
opposite the splenium of the corpus callosum; and passes upward 
and forward to emerge on the outer surface of the hemisphere, 
just in the great longitudinal fissure. 
By these primary fissures the hemisphere is divided into five 
lobes-frontal, parietal, occipital, temporo-sphenoidal, and cen- 
tral, or island of Reil. 
The frontal lobe is all of that portion of the brain situated in 
front of the fissure of Rolando, hence it would be bounded above 
by the great longitudinal fissure, on the outer surface, behind, 
by the fissure of Rolando, on the lower surface, behind, by the 
main bifurcation of the fissure of Sylvius. It should be noted 
that the inner face of the various lobes of each hemisphere is not 
described along with the external and inferior faces the reason 
being that the convolutions and fissures on the internal face do 
not confine themselves to lobes, but extend in many cases 
throughout the entire length of the hemisphere. 
The parietal lobe is bounded above by the great longitudinal 
fissure, in front by the fissure of Rolando, below by the hori- 
zontal limb of the fissure of Sylvius, and behind by the parieto- 
occipital fissure and a line drawn in continuation of that sulcus 
to the termination of the horizontal limb of the fissure of 
Sylvius. This fissure lies mainly on the inner face of the hemis- 
phere, so that on the outer face, the convolutions of the parietal 
become continuous with those of the occipital lobe. 
The occipital lobe is cut off on its inner face by the parieto- 
occipital fissure from the parietal lobe, this fissure being its 
anterior boundary. Above it is bounded by the longitudinal fis- 
sure, while below its convolutions run into the convolutions of 
the parietal and temporo-sphenoidal lobes, there being no fissure 
to form a separation. 
The temporo-sphenoidal lobe is that portion which lies in 
the middle fossa of the skull. On the inferior surface of the 432 
DESCRIPTIVE ANATOMY. 
base of the brain it is bounded in front by the fissure of Sylvius; 
externally, it is bounded above by the horizontal portion of the 
fissure of Sylvius; while posteriorly it blends around this hori- 
zontal limb of the fissure of Sylvius with the occipital and parie- 
tal lobes. 
The island of Reil is a cluster of five or six convolutions, situ- 
ated in the bifurcation of the fissure of Sylvius; and hidden 
under the fused lower extremity of convolutions which belong 
to the frontal and parietal lobes. 
Convolutions and Sulci of the External Surface of the Hemisphere. 
The convolutions and sulci of the frontal lobe are usually de- 
scribed as consisting of three, those found on the external sur- 
face and those on the inferior surface, which is frequently de- 
scribed as the orbital lobe. The subdivision is unnecessary, the 
convolutions being continuous with one another. In brains with 
a small number of convolutions it will be seen that in front of 
the central fissure, and running parallel with it, is a sulcus of 
the same character, but of less depth. This is called the pre- 
central sulcus. It commences near the bifurcation of the fissure 
of Sylvius and passes upward nearly to the great longitudinal 
fissure. This sulcus cuts off a convolution bounded in front 
by the precentral sulcus and behind by the fissure of Rolando, 
which is known as the ascending frontal convolution (anterior 
central gyrus). Two small sulci (superior and inferior frontal 
sulci) extend forward from near the precentral sulcus. Some- 
times they run into the precentral sulcus; but as a rule they do 
not. These extend straight forward to the anterior extremity 
of the frontal lobe, cutting off short convolutions, which are 
known from above downward as first, second, and third frontal 
convolutions, or occasionally as superior, middle, and inferior 
frontal gyri. If these convolutions be traced around to the in- 
ferior surface of the frontal lobe, it will be seen that here also 
are three convolutions, sometimes described as the first, second, 
and third orbital convolutions, numbered from within outward 
and backward; but in reality the continuation of the first, sec- 
ond, and third frontal convolutions. On the orbital surface, THE CENTRAL NERVOUS SYSTEM. 
433 
close to the great longitudinal fissure, is a narrow but deep 
sulcus, which lodges the olfactory nerve. External to this is 
another sulcus, less well-marked, which is the external boundary 
of the first orbital convolution, the continuation of the first 
frontal. The second sulcus, marking off the second and third 
orbital convolutions, or middle and inferior frontal convolu- 
tions, runs transversely, and is usually divided into two or more 
limbs, so that the second orbital convolution lies in front of 
the third. 
The ascending frontal convolution begins below near the bi- 
furcation of the Sylvian fissure, and is connected, around the 
lower end of the precentral sulcus, with the third frontal con- 
volution, forming a part of the operculum. Generally, also, it 
is connected, around the lower end of the fissure of Rolando 
with the ascending parietal convolution; and these two convo- 
lutions are nearly united around the upper end of the Rolandic 
fissure. 
The first, or superior, frontal convolution is limited above by 
the longitudinal fissure (supero-medial border) and below by 
the first frontal sulcus. It passes directly forward from the 
precentral sulcus, around the upper end of which it is connected 
with the ascending frontal convolution, and, winding around 
the anterior extremity of the frontal lobe, becomes continuous 
with the so-called first orbital convolution bounded by the medial 
arbital border. On its orbital surface this convolution is marked 
by a deep antero-posterior sulcus. 
The second, or middle frontal convolution is bounded above 
by the first, and below by the second frontal sulcus. It is shorter 
than the preceding convolution, with which it fuses around the 
end of the first sulcus. Passing around the front of the frontal 
lobe, it becomes continuous with the second orbital convolution, 
which occupies the antero-external aspect of the orbital surface 
of the frontal lobe. 
The third, or inferior, frontal convolution is cut off from the 
second by the second frontal sulcus, but fuses around the pos- 
terior extremity of that sulcus, with that convolution. It is 
very short and does not reach the anterior extremity of the 434 
DESCRIPTIVE ANATOMY. 
hemisphere, but winds around its outer aspect to become con- 
tinuous with the third or posterior orbital convolution. 
The convolutions of the parietal lobe are the ascending parietal, 
the superior parietal, and the inferior parietal. 
The ascending parietal (posterior central gyrus) is cut off 
by the intra-parietal sulcus. 
This is one of the most variable sulci on the outer surface of 
the hemisphere. It consists of three limbs, which may or may 
not be joined together. Commencing above the fissure of Syl- 
vius, it passes upward and backward parallel with and behind 
the fissure of Rolando to near the great longitudinal fissure. 
From a little above its centre a branch passes nearly directly 
backward, separating the superior from the inferior parietal 
convolutions. The vertical portion of this sulcus is named the 
post-central; the remainder is called the intraparietal sulcits. 
There may be found here three separate and distinct sulci, or 
the intraparietal may unite with either division of the post-cen- 
tral, and the third one exist in a separate sulcus. 
That portion of the lobe which is bounded in front by the fis- 
sure of Rolando, and behind by the post-central sulcus is called 
the ascending parietal convolution (post central gyrus). That 
portion between the great longitudinal fissure above, the intra- 
parietal sulcus below, and the external portion of the parieto- 
occipital fissure behind, is called the superior parietal convolu- 
tion. That part which lies between the horizontal limb of the 
fissure of Sylvius below, and the intra-parietal sulcus above and 
in front, is called the inferior parietal convolution. This in- 
ferior parietal convolution is frequently divided by a small sec- 
ondary sulcus into two portions, an anterior lying above the fis- 
sure of Sylvius, called the supramarginal, and a posterior, which 
extends around the horizontal limb of the fissure of Sylvius and 
blends with the occipital lobe, called the angular gyrus, or con- 
volution. 
It will be seen that the fissure of Rolando reaches neither the 
great longitudinal fissure nor the fissure of Sylvius, hence around 
the two extremities of this fissure the ascending frontal and 
ascending parietal convolutions communicate with one another. 
At the lower extremity of the fissure of Rolando the ascending THE CENTRAL NERVOUS SYSTEM. 
435 
frontal convolution communicates with the ascending parietal, 
and also with the third frontal convolution. That portion which 
connects with the third frontal convolution lies in the interval 
between the two limbs of the fissure of Sylvius, and forms the 
overhanging portion of brain substance, the operculum, which 
conceals the island of Reil. 
The convolutions of the occipital lobe are two in number- 
superior and inferior. These convolutions are separated by a 
sulcus called the lateral occipital sulcus. 
The end of the intraparietal sulcus (transverse occipital) is 
often continued across the occipital lobe, cutting off a small con- 
volution just back of the parieto-occipital fissure. 
The convolutions of the temporo-sphenoidal lobe. This lobe 
is divided by four sulci into five convolutions, though two of 
these convolutions are found on the inner surface of the hemis- 
phere. The two sulci found on the outer surface are the su- 
perior, or parallel sulcus and the middle, or second temporal, 
sulcus. The superior, or parallel, sulcus receives its name from 
being parallel with the fissure of Sylvius; the second, or middle 
temporal, sulcus is smaller and much less distinctly marked. 
The first temporo-sphenoidal convolution is bounded above by 
the horizontal limb of the fissure of Sylvius, and below by the 
parallel sulcus. At its posterior extremity it is continuous with 
the angular gyrus of the parietal lobe. The second temporo- 
sphenoidal convolution lies between the parallel sulcus and the 
second temporal sulcus, and is continuous posteriorly with the 
angular gyrus of the parietal and the second occipital convo- 
lution. 
The third temporo-sphenoidal, lying below the second tem- 
poral sulcus, is continuous posteriorly with the third occipital 
convolution. 
The island of Reil. On raising the operculum a group of five 
or six convolutions (though as few as three have been observed) 
are found lying in the interval between the diverging limbs of 
the fissure of Sylvius. These convolutions constitute the island 
of Reil. The sulci are only slight depressions, and the convolu- 
tions slight elevations. They all run in the same direction, up- 436 
DESCRIPTIVE ANATOMY. 
ward, backward and inward. The circular sulcus cuts off this 
set of convolutions from the adjoining lobes. 
Sulci and Convolutions on the Internal Face of the Hemisphere. 
The calloso-marginal sulcus (cingulate sulcus) commences 
near the base of the brain beneath the termination of the corpus 
callosum. It runs at first forward, following the rostrum of 
the corpus callosum, winds around its genu, thence backward, 
parallel with the body of the corpus callosum, until it reaches 
the posterior third of the brain, when it abruptly turns up- 
ward and passes to the great longitudinal fissure, behind the 
central fissure. 
The parieto-occipital, the second sulcus found on the inner 
face, begins at the splenium of the corpus callosum, and passes 
upward and backward to terminate on the external face of the 
hemisphere. 
The calcarine fissure, is the third of the sulci found on the 
inner face. It commences by a forked extremity near the end 
of the occipital lobe, and runs nearly directly forward, with a 
slight inclination downward, and joins the parieto-occipital sul- 
cus at an acute angle. 
The collateral sulcus, the fourth, is a long sulcus which ex- 
tends across the inner face of the temporo-sphenoidal lobe, sepa- 
rating the fourth and fifth temporo-sphenoidal convolutions. 
The dentate sulcus (hippocampal fissure) the last one, passes 
beneath the splenium of the corpus callosum to terminate near 
the commencement of the fissure of Sylvius. 
Of these sulci, the calcarine, the collateral, and the dentate 
all make appearances in the cavities found in the interior of the 
brain. The calcarine sulcus forms the hippocampus minor, or 
calcar avis (L. a bird's spur), in the posterior horn of the lateral 
ventricle. The collateral sulcus forms the eminentia collateralis; 
and the hippocampal, or dentate, sulcus forms the hippocampus 
major in the descending horn of the lateral ventricle. 
These sulci divide the internal surface into a marginal convo- 
lution, the gyrus fornicatus, the quadrate lobe, the cuneate, the THE CENTRAL NERVOUS SYSTEM. 
437 
uncinate gyrus, and the fourth and fifth temporo-sphenoidal 
lobes. 
The marginal convolution (suprafrental gyrus) is the inner 
face of part of the frontal and parietal lobes. It commences at 
the anterior perforated space, follows the windings of the cal- 
loso-marginal sulcus, then runs forward beneath the rostrum of 
the corpus callosum, winds upward around the genu, and passes 
backward until the calloso-marginal sulcus turns upward to the 
great longitudinal fissure, where the convolution terminates. It 
will be seen that this convolution corresponds to the inner face 
of the first orbital, the first frontal, the ascending frontal and 
ascending parietal convolutions. That part corresponding to 
the inner faces of the pre and post central gyri is called the pa- 
racentral lobule. 
The gyrus fornicatus (cingulate gyrus). Below the marginal 
convolution and between the calloso-marginal sulcus and the 
corpus callosum is the gyrus fornicatus, or convolution of the 
corpus callosum. It follows the same course as the preceding 
convolution until it reaches the posterior extremity of the 
corpus callosum, where it blends above with the quadrate lobe, 
winding around the splenium of the corpus callosum and chang- 
ing its name to become the uncinate, or hippocampal, convo- 
lution. 
The quadrate lobe (praecuneus) is bounded in front by the 
upturned portion of the calloso-marginal sulcus, behind by the 
parieto-occipital sulcus. Above, it is limited by the great longi- 
tudinal fissure (supero-medial border) ; and below it blends with 
the gyrus fornicatus. It is the internal face of the superior 
parietal convolution. 
The cuneate lobe (L. cuneus, a wedge) is bounded in front by 
the parieto-occipital sulcus, and below by the calcarine sulcus, 
and is the internal face of the first and second occipital convo- 
lutions. 
The hippocampal, or uncinate, lobe (L. uncinus, hooked) is a 
continuation downward and forward of the gyrus fornicatus. 
It is bounded above by the dentate fissure, and below by the col- 
lateral fissure. It extends as far forward as the commencement 
of the fissure of Sylvius; and inward to the point where the 438 
DESCRIPTIVE ANATOMY. 
gyrus fornicatus commences. Here it turns backward upon 
itself, forming the hook-shaped appearance which gives the con- 
volution its name. It is the fifth temporo-sphenoidal convolu- 
tion, the fourth temporo-sphenoidal lying beneath the collateral 
sulcus. The cingulate and hippocampal convolutions together 
form the limbic lobe. 
In addition to these convolutions, when the hemispheres are 
separated by cutting through the corpus callosum we, of course, 
see the fibres composing the corpus callosum and the inner face 
of the optic thalamus. 
The Base of the Brain. 
The lower surface, or base of the brain, is very irregular in 
outline, because it is fitted into the fossae of the skull. Anteriorly, 
on either side, is seen the orbital face of the frontal lobe which 
is somewhat triangular with the base backward and apex for- 
ward. Behind, and prolonged downward to fit in the middle 
fossa, is the temporo-sphenoidal lobe, and, behind this, the oc- 
cipital, also triangular with its base forward, flattened by pres- 
sure on the tentorium. The numerous appearances found on 
the base of the brain may be best studied by dividing them into 
two sets, viz: those which occur in pairs, and lie on either side 
of the mid-line; and those which are single and occupy the mid- 
line. 
Beginning on the mid-line in front and passing backward, we 
find the following appearances, viz: The great longitudinal fis- 
sure, with the rostrum of the corpus callosum seen at its bot- 
tom; the optic chiasm; the pituitary body, infundibulum and 
tuber cinerium leading the one to the other; the posterior per- 
forated space; the transverse fibres of the pons; the slight me- 
dian depression on the pons; the fissure between pons and me- 
dulla, and the anterior median fissure of the medulla. 
The appearances occuring in pairs and described on one side 
only, are: The orbital face of the frontal lobe with its two sulci 
and three convolutions; the peduncles of the corpus callosum; 
the groove or sulcus for the olfactory nerve and the olfactory 
bulb, and nerve, with the three roots of the latter; the beginning THE CENTRAL NERVOUS SYSTEM. 
439 
of the fissure of Sylvius; the optic nerve, internal to the roots of 
the olfactory; the anterior perforated space; the optic tract 
crossing the crus cerebri, and, internal to this, a corpus albicans; 
and, from this point backward, the roots of the cranial nerves. 
The longitudinal fissure and the corpus callosum are elsewhere 
described. The optic chiasm is formed by the union of the two 
optic tracts and gives off the optic nerves. It will be described 
with these nerves. The pituitary body, or hypophysis cerebri, is 
situated in the sella Turcica, bound down by a process of the 
dura mater. It consists of two lobes, anterior and posterior, 
separated by a fibrous lamina, the latter, during foetal life, com- 
municating with the third ventricle through the infundibulum. 
The infundibulum is a small tube of grey matter attached above 
to the lamina cineria and below to the pituitary body. It al- 
ways communicates with the third ventricle. The lamina cineria, 
or tuber cinerium, is a small mass of grey matter which forms 
part of the floor of the third ventricle. It is connected with the 
upper face of the optic chiasm and extends back to the corpora 
albicantia. 
The posterior perforated space is in the triangle formed by 
the crura on either side and the pons behind. It is made by a num- 
ber of small vessels which here pass into the optic thalami. The 
remaining appearances require no further description. 
The olfactory bulb (often destroyed in removing the brain) 
is an oblong rounded mass of grey matter which lies on the 
cribriform plate of the ethmoid and gives off numerous fila- 
ments to the nose. This bulb contracts to become the olfactory 
nerve which leads back to the fissure of Sylvius and divides into 
its three roots, which are described with the other cranial nerves. 
The anterior perforated space lies in the commencement of 
the Sylvian fissure. Antero-internally it is bounded by the optic 
nerve; internally, by the optic chasm, postero-internally, by the 
optic tract. Externally are the Sylvian fissure and the outer 
root of the olfactory nerve, while the middle root runs near the 
centre of the space. It is crossed by the peduncles of the corpus 
callosum, is connected with the lamina cinerium, lies beneath 
the corpus striatum, and receives its name from being perforated 
by numerous small vessels which pass into the latter body. The 440 
DESCRIPTIVE ANATOMY. 
optic tract will be described with the cranial nerves. The crus 
cerebri is a round cord which serves to connect the pons with 
the cerebrum. It is about three-fourths of an inch in length and 
is composed of two sets of longitudinal white fibres, superficial 
and deep (or anterior and posterior) and an intermediate bundle 
of gray matter called locus niger. The superficial white fibres 
pass through the pons from the anterior pillars of the medulla 
to the internal capsule. They form what is called the crusta. 
The deep longitudinal fibres, or tegmentum, pass from the oli- 
vary body and lateral and posterior columns of the medulla 
through the pons to the optic thalamus and cerebral cortex. 
Situated at the base of the brain is a six-sided space called 
the interpeduncular. It is bounded in front, on the mid-line, by 
the optic chiasm; behind, on the mid-line, by the transverse 
fibres of the pons; antero-laterally, by the optic tract; postero- 
laterally, by the crura cerebri. The corpora albicantia or mum- 
millaria are a pair of small rounded bodies, situated just behind 
the tuber cinerium, formed by the anterior pillars of the fornix 
which pass down to the base of the brain and then turn upward 
to reach the optic thalami. It is the knuckle formed by reverse 
ing their course which forms the corpora albicantia. This space 
contains the pituitary body, infundibulum, lamina, or tuber, 
cinerium, corpora albicantia, or mammillaria and the posterior 
perforated spot. It and its contents, form the floor of the third 
ventricle. 
Structure of the Cerebrum. 
When a horizontal slice, an inch or so thick, is removed from 
the upper surface of one hemisphere, the cut surface shows a 
central, oval, white portion surrounded, on the exterior, by a 
serrated grayish border; this is known as the centrum ovale 
minus. When both hemispheres have been cut to the same level, 
and this level corresponds to the depth of the central portion .of 
the longitudinal fissure, two centra ovalia minora are produced, 
connected in the centre by transverse fibres, forming a connect- 
ing band, called the corpus callosum; and the whole appearance, 
formed by the two centra ovalia minora and the corpus callosum, 
is called the centrum ovale ma jus. THE CENTRAL NERVOUS SYSTEM. 
441 
Corpus Callosum. 
The corpus callosum consists almost entirely of transverse 
fibres passing from one hemisphere to the other. Upon its upper 
surface there is a shallow groove, extending from before back- 
ward along the middle line, called the raphe; bordering each 
sid of the raphe is a slight ridge produced by a bundle of longi- 
tudinal fibres, the two ridges being called the nerves of Lan- 
cisi. External to these are seen a few other longitudinal fibres, 
producing slight ridges which are called the lateral longitudinal 
striae. When the corpus callosum is bisected longitudinally it 
is seen to be about four inches long and to bend vertically down- 
ward both in front and behind. The bent, rounded, posterior 
extremity is called the splenium, or pad, or bulb, the central por- 
tion the body, and the anterior bent portion the genu, which 
turns backward beneath the body for a short distance under 
the name of the rostrum. The rostrum divides into two cords, 
forceps anterior, which pass downward and backward to the 
base of the brain to terminate at the an'terior perforated space. 
The splenium divides into two similar bands, for the occipital 
lobes, called forceps posterior. The part between the anterior 
and posterior forceps extends into the temporal lobes and is 
called the tapetum. Contained in the substance of the brain, 
between its base and the corpus callosum, is an irregular cavity 
divided into several parts, two of which are known as the lateral 
ventricles, while the space is spoken of as the general ventricu- 
lar cavity. 
The General Ventricular Cavity. 
The ventricular CAVITY is a space found in the interior of the 
brain divided into two lateral, or first and second ventricles, and 
third and fourth ventricles, these cavities all communicating 
with one another by means of small foramina. The general ven- 
tricular cavity exists between the corpus callosum and velum 
interpositum above, the interpeduncular space at the base of 
the cerebrum, and the upper surface of the pons Varolii and the 
medulla oblongata below. The lateral ventricles exist in the 
two hemispheres of the cerebrum, separated from one another 442 
DESCRIPTIVE ANATOMY. 
on the mid-line by a thin septum. The third ventricle lies below 
the two lateral ventricles, and the fourth is below and behind 
the lateral ventricles, occupying a position on the medulla and 
the pons. 
The Lateral Ventricles. 
The right is usually described as the first, and the left as 
the second, lateral ventricle. The corpus callosum forms a 
part of the roof of the ventricular cavity; and upon its removal, 
the floor, formed of various objects, is brought into view. Each 
lateral ventricle consists of a body, and three extensions, called 
the horns of the ventricle, anterior, posterior, and middle. The 
entire cavity is roofed over in part by the corpus callosum, and 
in part by the frontal, parietal, occipital, and temporo-sphenoidal 
lobes. The inner wall is formed in part by a portion of brain 
tissue called the transparent septum (L. septum lucidum). The 
outer wall is the point of junction of the corpus callosum with 
the fibres of the cerebrum, while the floor is composed of a large 
number of objects, which will be enumerated later. The body 
of the ventricle is all of that portion which exists between the 
anterior horn and the middle and posterior horns. Its upper 
boundary is the lower surface of the corpus callosum; its inner 
boundary is, in front, the septum lucidum, and, behind that, the 
junction of the fornix and the corpus callosum ; its outer wall is 
the junction of the corpus callosum with the fibres of the cere- 
brum. The floor from before backward is made up of the corpus 
striatum, the tenia semicircularis, or horny band of Tarinus, the 
optic thalamus, the choroid plexus, and the fornix. Each of 
these requires a separate description. 
The corpus striatum (L. striatus, grooved or furrowed) is an 
oblong, or pear-shaped, grayish mass, with its large end in front. 
It is divided into two portions, called the intra and extra-ven- 
tricular portions, the former being also known as the caudate 
nucleus and the latter as the lenticular nucleus. Between these 
two, on the outer wall of the ventricle, is a portion of white 
matter, called the internal capsule. External to this comes the' 
extra-ventricular portion, the nucleus lenticularis (L. lens- 
shaped) ; and on the outer face of this again is a mass of white THE CENTRAL NERVOUS SYSTEM. 
443 
matter, called the external capsule. The white matter which de- 
scends between the two portions of the corpus striatum, and on 
the outer side of the nucleus lenticularis transmits impulses from 
the surface of the hemisphere to the medulla oblongata, and 
through that to the spinal cord. 
The tenia semi-circular is (stria terminalis) is a rounded cord, 
which lies in the groove between the corpus striatum and the 
optic thalamus. It may be traced into the anterior horn of the 
lateral ventricle, where it joins with the anterior pillar of the for- 
nix ; and thence backward into the roof of the descending horn, 
where it terminates in a projection of gray matter, the corpus 
amygdaloe. 
The optic thalamus is a mass of gray matter which projects 
into the floor of the body of the lateral ventricle, and forms the 
lateral walls of that third ventricle. It will be described in 
connection with that ventricle. 
The fornix (L. fornix, an arch, or vault) is a longitudinal 
band of white matter lying beneath the corpus callosum; and 
blended with its fellow of the opposite side behind, but sepa- 
rate in front. The anterior parts are called the columns, the 
posterior the crura, and the connecting part the body of the 
fornix. Behind it thins out into a broad, flattened band, the 
outer edge of which is called the corpus fimbriatum (L. fimbria, 
an edge, or border). It descends into the floor of the descend- 
ing horn, covering the projection in that space known as the 
hippocampus major. Between the two posterior crura of the 
fornix transverse fibres are stretched, which, from their sup- 
posed resemblance to a harp, have given the name of lyra to 
this portion of the fornix. Some of these posterior fibres spread 
out over the hippocampus as the alveus while a narrow band 
can be traced into the uncus. The two anterior columns de- 
scend to the base of the brain, not connected by transverse fibres, 
and pass downward to the corpora mammillaria, where they re- 
verse their course and turn upward, to be lost in the optic 
thalamus of the corresponding side. The anterior pillars of 
the fornix are connected with the peduncles of the pineal gland, 
and receive fibres from the septum lucidum. 444 
DESCRIPTIVE ANATOMY. 
The choroid plexus passes along the edge of the most internal 
object in the ventricle, the fornix. It is a mass of blood vessels 
arranged in the folds of the pia mater, which here projects into 
the interior of the brain. These vessels enter the descending 
horn of the lateral ventricle, pass upward through it, pass 
through the body of the ventricle, and continue their course 
beneath the body of the fornix, to unite with the choroid plexus 
of the opposite side, and form the true roof of the third ventri- 
cle. From the under surface of the fornix it passes backward 
through the transverse fissure of Bichat, joins with the velum 
interpositum, forming there a portion of the roof of the fourth 
ventricle, and becomes continuous with the general pia mater 
covering the brain. 
Of the three horns of the lateral ventricle the descending is 
the largest, the anterior intermediate in size, and the posterior 
the smallest. 
The anterior horn passes downward, forward, and outward, 
curving around the anterior extremity of the corpus striatum; 
and being entirely contained in the frontal lobe of the brain. 
The posterior horn is curved like a half-bent finger, or cock- 
spur, extends backward into the occipital lobe; and presents 
on its floor a slight projection, the hippocampus minor, or calcar 
avis, which is formed by the calcarine sulcus already described, 
on the inner face of the hemisphere. 
The descending horn pursues a tortuous course. It winds 
around the optic thalamus, passing first outward and backward, 
then downward and forward; and then, again changing its 
direction, it passes downward, forward and inward, to termin- 
ate near the extremity of the temporo-sphenoidal lobe. This 
horn of the ventricle is found first in the parietal lobe; but the 
major portion of it is in the temporo-sphenoidal lobe. 
At the junction of the descending and posterior horns is a 
slight eminence, frequently absent, called the eminentia col- 
lateralis or pes accessorius. Starting from this is a prominent 
projection, which follows the curvature of the horn itself, is 
formed by the dentate, or hippocampal, sulcus, and is called the 
cornu ammonis (L. a ram's horn), or hippocampus major, and 
terminates at the bottom of the horn in irregular projections, THE CENTRAL NERVOUS SYSTEM. 
445 
marked by intervening elevations and depressions, called the 
pes hippocampi. Lying upon the hippocampus major, and 
blended with it, is the thin lateral edge of the fornix, called the 
corpus fimbriatum, while rising behind this is that portion of 
the choroid plexus which passes into the descending horn. The 
gray matter in the descending horn covering the edge of the 
hippocampus major is the investing gray matter from the den- 
tate sulcus, and is known as the fascia dentata. 
At the junction of the anterior horn with the body of the 
lateral ventricle an opening is observed upon either side, which 
communicates with the third ventricle, and through which the 
choroid plexus of the lateral unites with the choroid plexus of 
the third ventricle. This opening is known as the foramen of 
Munro (inter-ventricular foramen). 
It will be noticed that the descending horn of the lateral ven- 
tricle follows the course of the optic thalamus, and hence that 
that body forms the roof of the descending horn throughout 
its extent. 
The Third Ventricle. 
The third ventricle of the brain is bounded above by the 
choroid plexus, above which is found the under surface of the 
body of the fornix. Below its floor slopes from behind down- 
ward and forward; and is made up of the structures which are 
included in the inter-peduncular space. The lateral walls are 
formed by the optic thalami. Instead of a posterior wall there 
is an opening, the aqueduct of Sylvius, or the iter a tertio act 
quantum ventriculum. The anterior wall is formed by a small 
bundle of gray matter, which is called the anterior commissure 
of the brain (L. committere, to join). This anterior commissure 
is found at the point where the hemispheres are nearly in con- 
tact, and consists of an interchange of white fibres between the 
temporal lobes. It lies just in front of the anterior pillars of 
the fornix, and its fibres pass outward and backward to reach 
the temporal lobes. Stretching across from the optic thalamus 
of one side to the same body of the opposite side is a second 
commissure, consisting of gray matter, and called the middle, 
or soft commissure of the brain (massa-intermedia). This con- 446 
DESCRIPTIVE ANATOMY. 
sists of the interchange of fibres between the optic thalamic 
and is frequently broken in the dissection of the brain. The 
posterior commissure, or third set of communicating fibres 
found in the third ventricle, extends between the posterior ex- 
tremities of the two optic thalami, and consists of white fibres, 
these fibres forming one of the boundaries of the aqueduct of 
Sylvius. Above the aqueduct of Sylvius is a small reddish-gray 
body, the pineal gland (L. pinea, a pine cone), from which pro- 
ceed two processes of gray matter, called the peduncles of the 
pineal gland. These peduncles pass forward on the upper in- 
ner face of each optic thalamus to terminate by blending with 
these bodies. The two unite behind in the commissure of the 
peduncles of the pineal gland. The depressed surface between 
the pineal gland and the extremity of the thalamus is the triga- 
num habenulae. 
An examination of the third ventricle will show that there 
are five openings communicating with other cavities of the 
brain. Two are found upon its antero-lateral wall, the foramina 
of Munro; two in its posterior wall, the aqueduct of Sylvius 
and the transverse fissure, and the fifth in the floor, the in- 
fundibulum. It will be remembered that at the base of the 
brain, occupying the anterior portion of the inter-peduncular 
space was seen the pituitary body, the infundibulum, the tuber 
cinerum, and the lamina cineria. Through the last three passes 
the small opening which leads from the floor of the third ventri- 
cle, downward to the pituitary body. 
The foramina of Munro are bounded above by the anterior 
pillars of the fornix, in front by the anterior commissure, be- 
hind by the anterior extremity of the optic thalamus. Through 
these two openings the choroid plexus of the lateral ventricle 
descends into the third ventricle. They present a somewhat 
Y-shaped appearance, the tail of the Y being represented by 
the union of the choroid plexuses, while the two arms are repre- 
sented by the portions in the lateral ventricles. Thus while the 
two lateral ventricles communicate with one another, the com- 
munication is indirect. In order that fluid may pass from one 
lateral ventricle to the other it is necessary to pass from the 
right lateral ventricle into the third ventricle, down to the tail THE CENTRAL NERVOUS SYSTEM. 
447 
of the Y; then to ascend through the left foramen of Munro along 
the second arm of the Y into the left lateral ventricle. 
The aqueduct of Sylvius (aqueductus cerebri), the opening in 
the posterior wall, passes downward and backward, running 
beneath the four projections of brain substance, called the cor- 
pora quadrigemina (L. fourfold bodies), and passes into the 
superior angle of the fourth ventricle. The communication thus 
established shows the general ventricular cavity to be continu- 
ous, the right and left lateral communicating through the in- 
tervention of the third and the foramina of Munro, the third in 
its turn communicating through the aqueduct of Sylvius with the 
fourth, and the fourth, by the foramen of Arantius, communicat- 
ing with the ventricular cavity found in the spinal cord, i. e., 
the central canal of the cord. 
The Fifth Ventricle. 
The fifth ventricle is described in the brain as consisting 
of the minute space between the two layers of the septum 
lucidum. It should be borne in mind, however, that the fifth 
ventricle has no connection with the general ventricular cavity. 
The fourth ventricle, rising behind the pons and the medulla, 
will be described in connection with these portions of the brain. 
Corpora Quadrigemina. 
The corpora quadrigemina are situated above the aqueduct 
of Sylvius, and, as their name implies, are divided into four 
bodies, two on either side of the mid-line. The anterior pair are 
called the nates (superior colliculus), the posterior the testes 
(inferior colliculus). On the posterior extremity, or pulvinar, 
of the optic thalamus are found two minute projections, called 
the corpora geniculata, internal and external. From each of the 
nates there proceeds a small white band, while from each of 
the testes a more prominent band passes upward and forward 
under the outer gerniculate body. These rounded cords are 
known as the superior and inferior brachia. The superior bra- 
chium passes upward and outward between the pulvinar and 448 
DESCRIPTIVE ANATOMY. 
inner geniculate body to join the optic tract. From the testes 
two bundles of fibres proceed downward, outward, and back- 
ward to join the cerebellum. These are the superior peduncles 
of the cerebellum,, or upper lateral boundaries of the fourth ven- 
tricle (brachia conjunctiva). It is between these two that the 
superior medullary velum, or valve of Vieussens, extends. 
The pineal gland, a small reddish projection, lies between the 
two nates. It consists of two lobes; and in its interior is a 
minute cavity, which contains a small amount of viscid fluid. 
It is held in place by four peduncles, or cords, two of which 
pass downward from the base of the gland to the optic thalami, 
while the other two have been noticed in the third ventricle as 
passing forward along the upper lateral aspect of the optic 
thalami to reach the anterior crura of the fornix. 
The Pons Varolii. 
The pons varolii consists of superficial transverse fibres, 
which, passing across the mid-line, enter the lobes of the cere- 
bellum, forming the middle peduncles of that portion of the 
encephalon, and acting as commissural fibres. Beneath this 
layer of fibres are two rounded bundles of longitudinal fibres, 
which pass forward from the medulla to the cerebrum and 
emerging from the anterior border of the pons, form the crura 
of the cerebrum, the postero-lateral boundaries of the inter- 
peduncular space. These crura are found to expand on entering 
the corresponding hemispheres of the cerebrum, and to assume 
a fan-shaped appearance, the corona radiata, or bands of white 
fibres which transmit impulses from the cortex of the cerebrum 
to the spinal cord. They are separated into two bundles by the 
thin layer of gray matter, called the locus niger. 
The Medulla Oblongata. 
Immediately below the pons is seen the medulla oblongata, 
which effects the junction between the various portions of the 
brain and the spinal cord. It is about an inch and one-half in 
length and three-quarters of an inch wide at the widest portion THE CENTRAL NERVOUS SYSTEM. 
449 
of it; and presents for examination anterior and posterior and 
two lateral surfaces, superior and inferior extremities. 
The anterior surface, which looks downward as well as for- 
ward, rests upon the basilar process of the occipital bone; while 
the posterior surface, a part of which is flattened and looks up- 
ward as well as backward, lies beneath the cerebellum. 
Just where the medulla joins the pons there is a deep con- 
striction, or groove which extends completely around the 
medulla; but is deeper on the anterior than on the posterior face. 
As the medulla transmits the fibres to and from the spinal 
cord, it must correspond nearly to the arrangement of the cord 
itself, consequently we find pillars in the medulla corresponding 
in a great measure to the same pillars found in the cord. They 
are, however, not so numerous, nor are they arranged in pre- 
cisely the same way. The medulla, like the cord, is divided 
along its anterior and its posterior face by two vertical fissures, 
which are continuous with the anterior and posterior median 
fissures of the cord. Lying by the side of the anterior median 
fissure, and separated by that fissure from its fellow, is a small 
portion of the medulla, called the anterior pyramid. It is, in 
part, the direct continuation upward of the anterior pyramid 
of the cord, but about two-thirds of its fibres belong to the 
crossed pyramidal tract (lateral cerebro-spinal) of the cord, 
so that the decussation of these fibres takes place before the 
cord terminates in the medulla. Behind this anterior pyramid, 
near the upper extremity of the medulla, is an oblong projection, 
called the olivary body. This olivary body is concealed in the 
lower portion, where the fibres are deeply seated and are covered 
by other portions of the medulla, and above it is made prominent 
by the divergence of the anterior pyramid and the fibres forming 
the restiform body. Behind the olivary body is a large and 
prominent body, the restiform (L. restis, a rope; forma, shape) 
which carries the direct cerebellar tract of the cord, and ter- 
minates by forming the inferior peduncles of the cerebellum. 
The restiform is separated from the olive by the roots of the 
ninth, tenth and eleventh nerves. 
Next to the restiform body is the fourth and last portion 
of the medulla, the posterior pyramid, this portion of the medulla DESCRIPTIVE ANATOMY. 
450 
carrying the fibres which in the cord are known as the columns 
of Goll and Burdach. The posterior pyramid, as it passes up- 
ward, blends with the restiform body; and the two pass together 
into the cerebellum to form its inferior peduncles. The anterior 
pyramids passing through the pons Varolii, enter into the for- 
mation of the crura cerebri. The olivary fibres disappear at 
the upper extremity of the medulla, sinking deeply into the 
pons, and probably aid in forming the commissural fibres which 
exist between the two lobes of the cerebellum as the superficial 
fibres of the pons. 
Along the mid-line of the upper surface is seen a fissure, on 
either side of which are the appearances on this face of the 
medulla. On either side are seen the striae acousticae, below 
these and next the mid-line is an elevation called trigonum 
hypoglossi, external to and below that is a slight triangular de- 
pression, trigonum vagi, while below these the expanded end 
of the funiculus gracillis, called the clava, and next the cuneate 
tubercle and funiculus cuneatus may be seen leading down to 
the cord. Between the diverging clavae is seen that flattened 
triangle called calamus scriptorius. 
The Fourth Ventricle. 
The fourth ventricle is diamond-shaped, having a superior 
and an inferior angle and two lateral angles. The inferior angle 
is formed by the diverging posterior pillars and the restiform 
bodies of the medulla; the superior angle being formed by the 
peduncles of the cerebellum. The two lateral angles are formed 
by the junction of the superior cerebellar peduncles with the 
inferior. The superior angle is formed by the divergence of the 
superior peduncles; and the inferior angle by the divergence of 
the inferior peduncles. 
At the superior angle is seen the lower opening of the aque- 
duct of Sylvius; at the inferior angle is seen the opening of 
the ventricle of Arantius. 
The roof of the fourth ventricle is formed above by that small 
portion of gray matter which stretches across from the peduncle 
of one side to the peduncle of the opposite side, and which is THE CENTRAL NERVOUS SYSTEM. 
451 
called the superior medullary velum, or more frequently, the 
valve of Vieussens. The lower portion of the roof is formed by 
the velum interpositum, above which is found the lower surface 
of the cerebellum. 
The upper one-half of the floor (fossa rhomboidea) is formed 
by the posterior surface of the pons, and the lower one-half by 
the posterior surface of the medulla oblongata. Along the 
mid-line is seen a fissure. Opposite each of the lateral angles 
is found a depression, called the fovea superior; and parallel 
with the median fissure are two rounded lobes of gray matter, 
called the fasciculi teretes (colliculus facialis). Near the central 
portion of the ventricle is sometimes seen a violet-colored 
streak, consisting of gray matter, lying just beneath a thin 
covering of white (which gives the singular color), and called 
the violet-colored band (L. toenia violacea). On the floor of 
this ventricle may be seen the origin of several of the cranial 
nerves. A few transverse fibres are seen extending across the 
ventricle near the lateral angle. These are the striae medullares 
and divide the space into superior and inferior triangles, the 
lower forming the colamus scriptorius containing the area 
acustica and trigonum hypoglossi. 
The Cerebellum. 
The cerebellum, or little brain, is divided into two hemi- 
spheres by a deep fissure found on its inferior aspect and a pro- 
jection found on the superior face. In the adult its relation in 
weight to the cerebrum is variously stated as one to thirteen 
and one to twenty, Cruveilhier giving the latter proportion. 
It is usually described as being divided into three lobes, a middle 
and two lateral, the middle being generally called the "worm," 
or vermiform process, and the two lateral, the "hemispheres." 
The hemispheres and the worm present a superior and an in- 
ferior surface. 
When viewed from above, the entire cerebellum seems undi- 
vided, the hemispheres being directly continuous through the 
middle of the worm. They slope from before downward, back- 
ward and outward. 452 
DESCRIPTIVE ANATOMY. 
On the inferior surface the appearance is entirely different. 
Here a deep groove, the vallecula, separates the two hemispheres, 
but the groove itself is partially filled by the lower aspect of 
the worm, which in its turn is subdivided by fissures into three 
portions. The groove in which the worm lies terminates an- 
teriorly and posteriorly in notches, the incisura cerebelli, an- 
terior and posterior. The anterior, wider and not so deep as the 
posterior, lies close to the pons and upper part of the medulla, 
while the posterior contains the falx cerebelli. The worm ex- 
tends into these notches, but does not completely fill them. The 
upper aspect of the worm is generally called the superior vermi- 
form process, and the lower the inferior vermiform process. 
Its sides are attached directly to the hemispheres of the cere- 
bellum; and probably act as commissural fibres. On the upper 
face the worm is divided into five main subdivisions named from 
before backward the lingula, lobulus centralis, culmen mon- 
ticuli, clivus monticuli and folium vermis or cacuminis. The 
lingula rests on the dorsal surface of the anterior medullary 
velum. The lobulus centralis, overlapping the lingula, is con- 
tinuous on either side with a small wing, the ala lobuli cen- 
tralis. The culmen monticuli is continuous with the anterior 
and the clivus with the posterior crescentic lobes (quadrangular 
lobes). The termination of the vermis superior, folium vermis, 
is a single fold continuous with the superior or semi-lunar 
lobe on either side. 
The inferior vermis is divided from before backward into four 
small projections called the nodule, noula, pyramid and tuber 
vermis or valvulae. These are connected with the following 
lobules on either side: The nodule with the flocculus; the uvula 
with the tonsils; the pyramid with the biventral, and the tuber 
vermis with the inferior or semi-lunar lobule. 
Each hemisphere of the cerebellum is divided into lobes; but 
we do not find in the cerebellum the convolutions which appear 
in the cerebrum. The cerebellum presents a laminated appear- 
ance., the fissures, or sulci, being deep and narrow, while the 
laminae overlap one another throughout the entire area of each 
hemisphere. Certain of these sulci, however, are deeper and 
more distinctly marked than others, so that it becomes possible THE CENTRAL NERVOUS SYSTEM. 
453 
to divide the cerebellum into lobes which, however, are less dis- 
tinctly bounded than the lobes of the cerebrum. Their names 
are fanciful, and derived in the main from a supposed re- 
semblance to other portions of the body. 
The great horizontal fissure begins in front at the pons and 
winds around the free border of the hemispheres to divide them 
into upper and lower surfaces. 
On the upper surface the lobes are very indistinct, and can 
scarcely be described as separate lobes. There are really five 
lobes on the superior surface, the connections of the lingula, 
froenum, ala lobuli centralis, the anterior and posterior square 
lobes and the superior semilunar. It will be noticed that the 
inferior vermiform process is that portion of the cerebellum 
which overhangs the fourth ventricle, and is its indirect roof, 
the pia mater intervening between the ventricle and the inferior 
vermiform process. 
The anterior square is cut off from the posterior square by 
the pre-clival fissure which runs through the worm just behind 
the culmen with which it is continuous. 
The posterior square lies behind the pre-clival and in front 
of the post-clival sulcus, and is continuous with the clivus. 
The superior semilunar lobe winds to the under surface. 
The first lobe on the inferior surface is found just in front 
of the great longitudinal fissure and is known as the flocculus. 
It is just external to the ala lobuli centralis. On the lower sur- 
face of each hemisphere, close to the median fissure, is a small 
projection of the cerebellum cut off by a deep fissure, the tonsils, 
or amygdalae from their supposed resemblance to a gland in 
the throat. Beyond the tonsils, and cut off by the fissure, is a 
curved lobe, which is called the digastric, or biventral lobe. 
Next to this, and behind the post-pyramidal sulcus is a narrow 
curved lobe which extends from the median fissure behind the 
pyramid around to the front of the cerebellum, nearly as far 
as the anterior median fissure. This lobe is very narrow, and 
is called the slender lobe. Behind the slender lobe, and occupy- 
ing the posterior extremity of the cerebellum, is another long 
and slender lobe, which borders the slender lobe, extending from 
the posterior extremity of the median fissure around to the front DESCRIPTIVE ANATOMY. 
454 
of the flocculus. This is known as the postero-inferior, or in- 
ferior semi-lunar, lobe. 
The inferior surface of the worm is deeply seated in the 
vallecula. 
The Spinal Cord. 
The spinal cord is the great connecting link between the 
brain and the various members of the body. It seems to cor- 
respond partially to a mass of insulated wires, a large portion 
of its work being the transmission of impulses to and from 
the brain; but it contains nerve centres which in themselves 
originate impulses, hence it is not merely a bundle of transmit- 
ting fibres. It is markedly similar to the brain in the arrange- 
ment of its membranes, and to some extent in its functions; but 
is dissimilar in the arrangement of the mass of gray and white 
matter. 
Membranes of the Spinal Cord. 
The MEMBRANES of the spinal cord, like those of the brain, 
are three in number, and bear the same names as those of the 
brain, the dura mater, the pia mater and the arachnoid. 
Dura Mater. 
The dura mater of the spinal cord is, however, unlike that 
of the brain, much too large for the cord which it envelops. It 
lines the interior of the spinal canal, is firmly attached to the 
bodies of the vertebrae, and sends off prolongations for each of 
the thirty-one pairs of spinal nerves, which accompany these 
nerves until they leave the spinal column. The inner face of 
the dura mater is lined by the arachnoid, as is the case in the 
brain; and it should be borne in mind that the membranes of 
the spinal cord are all directly continuous with those of the brain. 
Arachnoid. 
The ARACHNOID forms here, as in the brain, a serous mem- 
brane, covers the entire surface of the cord, and lines the inner THE CENTRAL NERVOUS SYSTEM. 
455 
face of the dura. It does not closely hug the cord; but between 
it and the cord is found a continuation of the mis-named sub- 
arachnoidean space. Between the visceral layer covering the cord 
and the parietal layer covering the dura is a second space which 
is known as the sub-dural, and it really lies between the folds 
of the arachnoid itself. 
Pia Mater. 
The PIA mater covers the cord nearly as it does the brain, 
but with some slight differences. It sends prolongations to ac- 
company the nerves which leave the spinal cord, it conveys the 
blood vessels as in the brain; but it also gives ligamentous fibres, 
which are not found in the cranium. Between each pair of spinal 
nerves will be found a wedge-shaped portion of fibrous tissue, 
which is derived from the pia, and which, passing to the lateral 
aspect of the cord, becomes attached to it, while the point of 
the wedge extends outward to blend with the dura. These pro- 
longations form the lig amentum denticulatum, and serve the 
purpose of retaining the cord steadily in position, and of pre- 
venting its movement in the large chamber furnished for it by 
the dura. 
Cord. 
The CORD itself is nearly, though not quite, cylindrical, being 
slightly flattened in the antero-posterior direction. It is seven- 
teen or eighteen inches in length, and varies in weight, as does 
the brain, with the period of life, cause of death, and even with 
the period after death when the cord is removed. It corresponds 
in length to the upper two-thirds of the spinal canal in the adult, 
though it is longer relatively in the foetus, extending here to the 
bottom of the sacral canal; but apparently the vertebrae grow 
more rapidly than the cord and hence the cord is carried up- 
ward in the canal until it reaches about the level of the lower 
border of the first or upper border of the second lumbar ver- 
tebra. The cord presents an enlargement in the cervical region, 
where the branches are given off which supply the upper ex- 
tremity ; and a similar enlargement in the lower thoracic region, 
where the branches are given off which supply the lower ex- 456 
DESCRIPTIVE ANATOMY. 
tremity. Of course, in the living being, its curvature cor- 
responds to the curvature of the spinal column. 
When the membranes are removed, it will be seen that the 
cord presents two median fissures, one anterior, and one pos- 
terior. 
The anterior fissure is wide, but shallow; while the posterior 
fissure is very deep and narrow. In addition to these two fis- 
sures, the spinal nerves, rising by two bundles of roots, called 
the anterior and posterior, make incomplete and irregular fis- 
sures, which extend through the length of the cord, and serve 
to form the two lateral fissures. Hence it will be seen that the 
cord is divided into an anterior column, a posterior column, and 
a lateral column, the last being separated from the other two by 
the anterior and posterior roots of the spinal nerves. There are, 
however, other columns in the cord, determined more by patho- 
logical than by anatomical examination. 
It will be seen that the cord, unlike the brain, is arranged 
with all of its gray matter in the centre, and the white matter 
surrounding it; and on section of the cord in living animals 
degeneration takes place in two directions. Those fibres which 
convey impulses to the brain degenerate upward, while those 
which convey impulses from the brain degenerate downward. 
These pathological changes warrant the division of the cord into 
a number of tracts, not noted anatomically. 
As in all portions of the brain, the two lateral divisions of the 
cord, separated by the anterior and posterior median fissures, 
which correspond in fact to the great longitudinal fissure of the 
brain, communicate across this fissure by means of commissural 
fibres. The roots of the spinal nerves extend through the white 
matter of the cord, and communicate with the gray matter in 
its interior. This gray matter, in addition to furnishing trophic 
centres, contains centres which act apparently of their own 
volition without stimulation from the brain. As a matter of 
course these centres are, however, presided over by the brain, 
and can be restrained in their action by the higher centres. 
The total number of tracts in the cord is large; and we do 
not find the corresponding tracts in the medulla, but in many 
cases two or more tracts are blended into one in the transmis- THE CENTRAL NERVOUS SYSTEM. 
457 
sion from the cord to the brain. Commencing at the anterior 
median fissure the first tract is called the anterior pyramid, 
or anterior pyramidal tract, and next to this is found the an- 
terior ground zone, or anterior root zone, being that portion of 
the cord in front of the anterior roots of the spinal nerves. 
Then comes behind the spinal nerves a second ground zone, 
which is, however, called the lateral bundle, and external to 
both of these and superficial to them is the antero-lateral tract, 
which conveys both ascending and descending fibres to the cere- 
brum. Behind this tract, also on the superficial surface of the 
cord, is the direct cerebellar tract which extends as far as the 
posterior root zone; and between the direct cerebellar and the 
gray matter in the interior of the cord is the crossed pyramidal 
tract. Behind the posterior root zone are two tracts, the one 
next to the roots of the nerves being Burdach's column, or the 
postero-lateral column, while the one next to the postero-median 
fissure is the column of Goll, or the postero-median column. 
When these columns are traced upward into the medulla, it 
will be found that the column of Goll and the column of Burdach 
unite to form the posterior column of the medulla, or as it is 
frequently called, funiculus cuneatus (L. Dim. of funis, a cord; 
cuneatus, wedge-shaped) ; that the direct cerebellar tract passes 
into the restiform body; that the crossed pyramidal and the 
direct pyramidal enter into the anterior pyramid of the medulla, 
when the direct pyramidal will pass upward on its own side, 
while the crossed pyramidal passes to the posterior side. The 
antero-lateral or ascending and descending cerebellar tracts, 
with the anterior root zone, pass upward into the lateral column 
of the medulla, to ascend with it to form the central fibres of 
the pons Varolii. 
In addition to these white transmitting fibres, the cord con- 
tains in its interior the mass of gray matter before alluded to, 
which is arranged like the letter "H," the projections in front 
of and behind the cross-bar of the "H" being called the "horns." 
The posterior horns are long and slender, while the anterior 
horns are bluntly pointed. These masses of gray matter con- 
tain the fibres furnishing the various centres in the spinal cord. 
It will of course be seen that the branches which proceed from DESCRIPTIVE ANATOMY. 
458 
the spinal cord are collectively enormously larger than the cord 
itself, and it can be readily understood that large quantities of 
fibrous tissue serve in a measure to make up a portion of the 
bulk of the spinal nerves. 
The cord is nourished by the blood vessels which it carries 
in its pia matral covering; and these blood vessels are derived 
partly from the anterior and posterior branches of the vertebral 
arteries, and partly from the branches which enter the spinal 
canal springing from the intercostal and lumbar arteries. 
The Spinal Nerves. 
The spinal nerves consist of thirty-one pairs, which taking 
their origin from the spinal cord, pass outward from the spinal 
canal through the intervertebral foramina, and are distributed 
throughout the body. These nerves differ materially from the 
cranial nerves, for, whereas the latter are usually divided into 
separate nerves, having motor, general sensory, or special sen- 
sory functions, the spinal nerves are composed of bundles, per- 
forming all nervous functions. Some convey tactile sensations, 
some painful, some motor, and some various other functions. 
While these nerves may be traced into the spinal cord, their 
fibres pass through the various columns of the cord to reach 
different portions of the brain; and hence while the nerves are 
described as spinal nerves simply from their origin they are 
controlled by the higher centres located in the cerebrum. 
They differ from the cranial nerves also in their manner of 
distribution. The cranial nerves pass out as individual nerves 
to break up into branches distributed to various portions of 
the head, face, and viscera, having but slight communications 
with one another. The spinal nerves on the contrary unite very 
intimately with one another after their emergence from the 
spinal column; and form plexuses from which branches are given 
off to carry out the distribution of the plexus. There are four 
of these plexuses, called the cervical, brachial, lumbar and sacral. 
Interposed between the brachial and the lumbar are a set of 
spinal nerves, the dorsal, which do not unite to form plexuses, 
but are distributed individually like the cranial nerves. Some THE CENTRAL NERVOUS SYSTEM. 
459 
writers mention a coccygeal set; but these in reality belong to 
the sacral plexus. 
Each spinal nerve as it emerges from the cord is surrounded 
by a prolongation of the dura mater, which lines the spinal canal 
and forms a sheath for the nerve as far as the intervertebral 
foramen. From this point it becomes continuous with the ordi- 
nary fibrous sheath, which envelops every nerve, and ceases to 
have the characteristics of the dura mater lined by its arachnoid 
membrane. 
Moreover each nerve presents upon it at its emergence an 
enlargement; and as every nerve arises by an anterior and a 
posterior root, this enlargement, or ganglion, is confined to the 
posterior root. The posterior root of a spinal nerve conveys its 
sensory fibres, while the anterior root conveys the motor fibres. 
The anterior root also has its trophic centre situated in the 
spinal cord, so that cutting that nerve causes degeneration down- 
ward into the nerve, which has been cut loose from its trophic 
centre, while cutting the posterior root between the ganglion 
and the cord causes degeneration upward into the cord, because 
the trophic centre is located in the ganglion and not in the cord. 
It must be always remembered that while these fibres con- 
veying the various impulses exist in the spinal nerves they can- 
not be demonstrated anatomically. 
Each spinal nerve immediately after it emerges from the 
spinal canal divides into an anterior and a posterior branch, 
which must not be confused with the anterior and posterior 
roots. The posterior branches are small in size and compara- 
tively unimportant. They convey motor and sensory impulses 
to the muscles found in the back and neck, the posterior fibres 
of the sacral plexus, the lowest, conveying impulses to the lowest 
muscles of the trunk, while the limbs are supplied entirely from 
the anterior cords. It is the anterior cords which enter into 
the formation of the plexuses. 
The Cervical Plexus. 
The first plexus formed by the spinal nerves is called the 
cervical. It is the product of the four upper cervical nerves. The DESCRIPTIVE ANATOMY. 
460 
plexus is formed by the. communication of the anterior cords of 
these four cervical nerves, and is found opposite the middle of 
the sterno-cleido-mastoid muscle. Its principal distribution is 
to the muscles and integument of the neck. 
The plexus itself is formed in the following manner: The 
first cervical nerve divides into an anterior and a posterior 
branch, the posterior branch enters the sub-occipital triangle 
and supplies the recti and oblique while its anterior division, 
after receiving a communication from the eleventh and twelfth 
cranial nerves, sends downward a communication to the second 
cervical. The second cervical, after giving off a larger pos- 
terior branch than any other cervical nerve, sends a com- 
munication to the third, and the third, in like manner, sends 
a communicating branch to the fourth, which in its turn 
sends a branch to the fifth, which enters into the forma- 
tion of the brachial plexus. The internal branch of the pos- 
terior division of the third is called the great occipital nerve 
and is distributed to the skin of the scalp as far forward as the 
vertex. From this loosely-formed cervical plexus branches are 
given off which are distributed to the head, face, neck and chest. 
These branches are, for convenience of study, divided into two 
sets, superficial and deep, the superficial set consisting of three 
ascending named branches, and certain unnamed branches, 
which are called descending superficial branches. The deep set 
consists of muscular branches. 
The named branches of the superficial set are the superficialis 
colli, auricularis magnus, and occipitalis minor. 
Superficial Branches. 
Superficialis Colli. 
Auricularis Magnus. 
Occipitalis Minor. 
Superficialis Colli. 
The superficialis colli (transverse cervical), the first 
branch, is the product of the second and third cervical nerves; 
and like all the superficial branches from this plexus, it winds 
around the posterior border of the sterno-cleido-mastoid muscle, THE CENTRAL NERVOUS SYSTEM. 
461 
about at its middle, and becomes superficial in that situation. 
It then passes upward and forward, crosses the sterno-cleido- 
mastoid, and spreads out into a fan-shaped set of twigs, which 
after communicating with the facial nerve, are distributed to 
the skin covering the lateral aspect of the neck, as high as the 
chin and as low as the Sternum. 
Auricularis Magnus. 
The auricularis MAGNUS is the product of the second and 
third cervical nerves. After emerging from the posterior border 
of the sterno-cleido-mastoid, it crosses that muscle, and divides 
into three branches-auricular, facial, and mastoid. It lies be- 
neath the platysma, after perforating the deep fascia. 
1st. The auricular branch divides into several twigs, which 
are distributed to the skin on the back of the pinna, communicat- 
ing with the auricular branches of the seventh and tenth cranial 
nerves. 
2d. The facial passes over the parotid and after communicat- 
ing with the facial nerve, is distributed to the skin of that 
region. 
3d. The mastoid branch ascends to the mastoid process of the 
temporal bone and is distributed to the skin in that region 
after communicating with the seventh cranial nerve and occi- 
pitalis minor. 
Occipitalis Minor. 
The occipitalis MINOR is derived from the second cervical 
nerve. It passes upward nearly parallel with the posterior 
border of the sterno-cleido-mastoid muscle; and gives off three 
sets of branches, one, the auricular, passing to the back of the 
ear, one over the mastoid process of the temporal, where it 
communicates with the auricularis magnus, and the third, the 
largest, passing to the occipital bone, where it runs over the 
occipito-frontalis muscle, and is distributed to it and to the 
skin covering the occipital bone, communicating with the great 
occipital. 462 
DESCRIPTIVE ANATOMY. 
The Descending Superficial Branches. 
The unnamed descending superficial branches are pro- 
duced by the third and fourth cervical nerves. They emerge 
from beneath the sterno-cleido-mastoid muscle, like the pre- 
ceding branches, about opposite the middle of its posterior 
border. They are irregular in size and number. One set passes 
downward and inward toward the mid-line of the body, cross- 
ing the clavicle near its inner extremity and ending in the 
integument which covers the front of the thorax. The second 
set passes nearly vertically downward, to cross the middle of 
the clavicle, and be distributed to the integument covering the 
pectoral muscles, while the third set, called sometimes the 
acromial, or deltoid, passes outward, and is distributed to the 
skin in the neighborhood of the shoulder. 
Deep Branches. 
Muscular. 
Phrenic. 
Communicans Noni. 
Muscular Branches. 
The MUSCULAR BRANCHES are distributed to all of the muscles 
of the front of the neck with the exception of the de- 
pressors of the hyoid bone. They consist of a branch to the 
sterno-cleido-mastoid muscles, which arises from the second 
cervical and communicates with the eleventh cranium in the 
substance of the sterno-mastoid muscle; a branch to the scal- 
enus medius, coming from the third and fourth nerves; one 
to the levator anguli scapulae; and several branches to the 
trapezius, which are the product of the third and fourth cervical 
nerves and which communicate with one another. 
Besides this, there are some branches, sometimes described 
as internal, which supply the rectus capitis lateralis, the rectus 
capitis anticus major and minor. 
The longus colli is supplied by branches from the third and 
fourth. THE CENTRAL NERVOUS SYSTEM. 
463 
The Communicans Hypoglossi. 
The most important communicating branch is the COMMUNI- 
CANS hypoglossi. This nerve is the product of the second and 
third cervical nerves. It passes downward, forward, and in- 
ward, and unites with the descending branch of the hypoglossal 
on the front of the common carotid artery, immediately above 
the point at which the omo-hyoid crosses that vessel. After 
this communication it passes with the descendens noni to be 
distributed to the muscles of the infra-hyoid group, or depres- 
sors of the hyoid bone, with the exception of the thyro-hyoid, 
which is supplied by a branch from the hypoglossal nerve itself. 
The Phrenic. 
The last and most important branch of the plexus is the 
PHRENIC NERVE, or internal respiratory of Bell. It is formed 
by contributions from the third and fourth cervical nerves, re- 
inforced by a small filament from the fifth. The course of the 
nerve on the two sides of the body differs. 
On the right side it descends on the front of the scalenus 
anticus muscle, reaches the inner side of that muscle just be- 
fore it crosses the subclavian artery, drops off to the inner 
side, and becomes an anterior relation of the first portion of the 
subclavian, though occasionally it remains on the scalenus an- 
ticus until after it has passed the artery. It then runs in the 
interval between the subclavian artery and vein, continues its 
downward course into the thorax, lying to the outer side of 
the right vena innominata and then the superior vena cava, 
passes in front of the root of the right lung, then lies on the 
pericardium between it and the right pleura, and finally pierces 
the diaphragm, and is distributed to that muscle from its under 
surface. 
The left nerve, formed in the same way, passes on the scal- 
enus anticus muscle to cross over the front of the first portion 
of the subclavian, then to descend in front of that vessel and 
opposite the interval between it and the left common carotid, 
lying to the outer side and in front of the pneumogastric nerve. 464 
DESCRIPTIVE ANATOMY. 
Then it crosses the end of the transverse aorta, passes downward 
on the pericardium, lying next to the left pleura, and then, 
like its fellow of the opposite side, enters the diaphragm and 
is distributed to it from its under surface. 
The Brachial Plexus. 
The brachial plexus is the second great plexus formed by 
the anterior cords of the cervical nerves. It is the result of 
inter-communications between the four lower cervical nerves 
and the greater portion of the first dorsal nerve. The manner 
of its formation differs in different individuals; but it is usually 
formed in the following way: The fifth and sixth cervical 
nerves unite to form a single cord; the eighth cervical and the 
first dorsal unite to form one cord, while the seventh cervical 
passes out alone. Then the seventh unites with the cord formed 
by the fifth and sixth, so that at one time there are but two 
cords in the plexus, one resulting from the union of the fifth 
and sixth with the seventh, and the other formed by the eighth 
cervical with the first dorsal. Shortly after, however, each of 
these two cords gives off a branch; and these branches unite 
to form a third cord in the plexus, this middle cord being the 
product of all of the cords which enter into the formation of 
the brachial plexus, except the fifth. 
The plexus is triangular in outline, with its base directed 
towards the spinal column and its apex extending downward, 
backward and outward towards the axillary space. It passes 
between the scaleni muscles; and comes into relationship with 
the subclavian artery in the second portion of its course. Here 
most of the cords lie above that vessel; but the branch derived 
from the dorsal nerve lies behind it. In the third portion of 
the subclavian artery the plexus lies above and to the outer 
side, but on a plane posterior to it. It then continues downward 
and outward, coming into relationship with the axillary artery, 
and lies first to its outer side; but in the second portion of 
that vessel, viz., that part behind the pectoralis minor muscle, 
the plexus consists of three cords, one to the inner side, one 
to the outer side, and one behind the axillary artery. Just at THE CENTRAL NERVOUS SYSTEM. 
465 
the termination of the second portion the inner and the outer 
cord each gives off a branch, and the two branches formed in 
this manner unite to form the median nerve, so that, on a line 
drawn from the tip of the coracoid process of the scapula down- 
ward and inward to the lower part of the third intercostal 
space, it will be seen that the axillary artery is completely sur- 
rounded by the cords of the plexus. The outer and inner cords 
lie on the outer and inner sides of the artery, the posterior cord 
behind it, and the branches which form the median nerve lie 
upon its front. 
Immediately after the formation of the median, that nerve 
drops to the outer side of the axillary artery, and maintains 
that relation to the termination of that vessel, while the re- 
maining cords of the plexus break up into their terminal 
branches. 
Branches of the Brachial Plexus. 
The distribution of the brachial plexus is chiefly to the upper 
extremity, supplying the muscles and integument; but before 
reaching its point of termination it gives off way-side branches, 
some muscular and some cutaneous, which are distributed to the 
lateral aspect of the chest, as well as to the muscles of the 
scapular group and the skin covering them. 
Wayside Branches. 
Suprascapular. 
Rhomboid. 
Posterior Thoracic. 
Anterior Thoracic, 
internal. 
Above the 
Clavicle 
Communicating. 
Below the 
Clavicle 
Anterior Thoracic, 
external. 
Subclavian. 
Scaleni. 
Longus Colli. 
Subscapular. 
Suprascapular. 
The suprascapular branch is derived from the fifth and 
sixth cervical nerves. It passes downward and outward parallel 466 
DESCRIPTIVE ANATOMY. 
with the posterior belly of the omo-hyoid muscle. Reaching 
the upper border of the scapula it passes through the supra- 
scapular notch beneath the transverse ligament, and, conse- 
quently, below the corresponding artery, enters the supra- 
spinatus muscle, gives motor fibres to that muscle and a twig 
to the shoulder joint, while the remaining portion of the nerve 
passes around the anterior border of the spine of the scapular 
to be distributed to the infraspinatus muscle. 
Rhomboid. 
The RHOMBOIDEUS branch is a product of the fifth cervical 
nerve. It passes through the fibres of the scalenus medius, and 
is then distributed to the rhomboid muscle, or muscles. 
Posterior Thoracic. 
The POSTERIOR THORACIC, Or EXTERNAL RESPIRATORY NERVE OF 
bell, is the product of the fifth, sixth and seventh nerves. It 
passes downward behind the brachial plexus and the first por- 
tion of the axillary, and is distributed to the serratus magnus 
muscle. 
Communicating. 
The communication with the cervical plexus is by means of 
a branch of the fifth cervical, which joins with the phrenic nerve. 
Subclavian. 
The nerve to the subclavius muscle is a slender twig, which 
is derived from the fifth cervical, and crosses the front of the 
third portion of the subclavian artery to enter the subclavius 
muscle. 
Longus Colli. 
The branch to the longus colli comes from the lower brachial 
nerves and passes outward to the muscle of that name. THE CENTRAL NERVOUS SYSTEM. 
467 
The branches given below the clavicle, besides the terminal 
ones, are the external and internal anterior thoracic and the 
subscapular nerves. 
External Anterior Thoracic. 
The external anterior thoracic, derived from the outer 
cord of the plexus, is distributed to the pectoralis major muscle, 
passing in front of the axillary artery. 
Internal Anterior Thoracic. 
The internal anterior thoracic, the product of the inner 
cord, passes between the first portion of the axillary artery 
and its vein, occasionally perforating the vein itself; and after 
receiving a communication from the external anterior thoracic, 
is distributed to the pectoralis minor muscle. 
Subscapular. 
The subscapular nerves are three in number, and are de- 
rived from the fifth, sixth, seventh, and eighth cervical nerves. 
They are known as the upper, middle, and lower. The upper 
is distributed to the subscapularis muscle alone, the middle 
accompanies the subscapular artery, and terminates in the latis- 
simus dorsi; while the lower is distributed to the teres major, 
furnishing some twigs to the subscapularis. 
Terminal Branches. 
Musculo-cutaneous. 
Internal Cutaneous. 
Lesser Internal Cutaneous. 
Median. 
Ulnar. 
Musculo-Spiral. 
Circumflex. 
The terminal branches of the brachial plexus originate 
from the cords of the plexus as follows: The internal cord pro- 468 
DESCRIPTIVE ANATOMY. 
duces the internal cutaneous, the lesser internal cutaneous, the 
ulnar, and the inner head of the median. The external cord, 
divides into two branches: one forms the outer head of the 
median, while the other is the musculo-cutaneous. The posterior 
cord divides into the circumflex and the musculo-spiral. 
The division of the plexus takes place on the beginning of the 
third portion of the axillary artery, which is here completely 
surrounded by the cords of the plexus; but immediately after 
the formation of the median, that nerve drops to the outer side 
of the axillary artery; and the relation is then, median and 
musculo-cutaneous to the outer side, internal and lesser internal 
cutaneous and ulnar nerves to the inner side, musculo-spiral 
behind, and circumflex behind as far as the interval between the 
teres major and lower border of the subscapularis, where it 
passes to the back of the humerus and ceases to be a relation. 
Musculo-Cutaneous. 
The MUSCULO-CUTANEOUS nerve, the product of the outer 
cord of the brachial plexus, receives fibres which can be traced 
to the fifth, sixth, and seventh nerves, passes downward as an 
external relation of the third portion of the axillary artery until 
it reaches the coraco-brachialis muscle. It then passes through 
the substance of that muscle, supplying the muscle with 
branches as it is transmitted through it. Emerging from the 
coraco-brachialis, it passes between the brachialis anticus and 
the biceps, runs into the interval between the brachialis anticus 
and the supinator longus, where it becomes superficial a little 
above the elbow joint, and passing across the outer front aspect 
of that joint, divides into two branches. The posterior branch 
passes downward and backward; and is distributed to the skin 
on the postero-external aspect of the forearm as far as the wrist. 
The anterior branch, supplying the integument of the antero- 
external face of the forearm, communicates with the radial 
nerve near the wrist, and extends as far as the skin covering 
the thenar eminence. THE CENTRAL NERVOUS SYSTEM. 
469 
The nerve in its course gives off muscular branches to the 
coraco-brachialis, the biceps, and the inner portion of the bra- 
chialis anticus. 
Internal Cutaneous. 
The internal cutaneous nerve is the product of the inner 
cord of the plexus; and is probably derived from the eighth 
cervical and first dorsal. It is an internal relation of the third 
portion of the axillary artery to the termination of that vessel; 
and then becomes an antero-internal relation to the brachial 
artery, lying in close companionship with the basilic vein. At 
the middle of the brachial artery the nerve, with the basilic 
vein, pierces the investing fascia, and, still remaining an an- 
tero-internal relation of the brachial artery to its termination, 
is, for its lower half, separated from that vessel by the deep 
fascia of the arm. 
At the elbow-joint it breaks up into branches, some of which, 
lying on the front of the bicipital fascia, are anterior relations 
of the brachial artery, but separated from it by this fascia. 
The remaining branches continue their course downward, being 
divided into an anterior and a posterior set, the anterior sup- 
plying the integument of the inner front aspect of the forearm 
as far as the wrist, while the posterior supply the integument 
on the postero-internal aspect of the forearm down to the wrist. 
Lesser Internal Cutaneous. 
The LESSER INTERNAL CUTANEOUS, or NERVE OF WRISBERG, 
arising from the internal cord, receives its branches from the 
eighth cervical and first dorsal. It is very irregular in its origin, 
and may be the product of the lateral cutaneous branch of the 
second intercostal nerve; but, as a rule, it simply receives a 
communication from that nerve. At first it is an internal rela- 
tion of the axillary artery, and is separated from that artery 
by the axillary vein. It continues downward, too distant to be 
considered a relation of the brachial artery, to the postero- 
internal aspect of the arm, and near the elbow turns backward 470 
DESCRIPTIVE ANATOMY. 
to be distributed to the integument on the lower third of the 
arm and in the neighborhood of the olecranon process. 
Ulnar. 
The ulnar nerve is the last branch of the internal cord of 
the plexus, and like the preceding branches, contains fibres from 
the eighth cervical and first dorsal nerves. It is first an internal 
relation of the axillary artery, lying between it and the lesser 
internal cutaneous nerve. It then becomes an internal relation 
of the brachial for the upper half of the course of that vessel, 
and at the middle of this artery it reaches the inferior profunda 
branch of the brachial. Accompanied by this latter branch, 
it passes backward, pierces the internal inter-muscular septum, 
and runs to the space between the internal condyle of the 
humerus and the olecranon process of the ulna, forming what 
is generally known as the "funny bone." The nerve then passes 
between the two heads of the flexor carpi ulnaris muscle; and 
at the junction of the upper third with the lower two-thirds of 
the forearm it becomes an internal relation of the ulnar artery. 
It then passes downward, lying on the fibres of the flexor pro- 
fundus digitorum, and maintains a continuous internal relation 
to the ulnar artery to the wrist joint. At this point it becomes 
superficial to the anterior annular ligament, passes to the outer 
side of the pisiform bone, and enters the palm of the hand, 
where it divides into a superficial and a deep branch. 
In the commencement of its course the nerve lies on the 
anterior face of the internal inter-muscular septum. At the 
middle of the arm it pierces this septum, and passes downward 
in the fibres of the triceps muscle, then behind the internal con- 
dyle of the humerus, then between the two heads of the flexor 
carpi ulnaris, separated from the ulnar artery for the upper 
third of the course of that vessel. Then the nerve lies with 
the flexor carpi ulnaris to its inner front side, and the flexor 
profundus digitorum behind it, and with the flexor sublimis 
digitorum and the ulnar artery to its outer side for the lower 
two-thirds of its course. THE CENTRAL NERVOUS SYSTEM. 
471 
The nerve gives off no branches until after it has passed the 
elbow joint, where it supplies muscular branches to the flexor 
carpi ulnaris and the inner half of the flexor profundus digi- 
torum. About three inches above the wrist joint it gives off a 
cutaneous branch, the dorsal cutaneous branch of the ulna, which 
■will be described later, and then a palmar cutaneous branch 
which enters the palm of the hand to supply the palmaris brevis 
and the skin over the hypothenar eminence. A few small twigs 
are given off to the elbow joint. On entering the hand it divides 
into a superficial and a deep branch. 
Superficial branch. After entering the palm, the superficial 
branch supplies the skin covering the hypothenar eminence, 
sends a twig to the inner side of the little finger, and a branch 
which bifurcates to supply the adjacent sides of the little and 
ring fingers, and lastly a communicating branch to the median 
nerve. 
The distribution of the collateral digital branches to the 
fingers is accomplished by the median and ulnar nerves. These 
branches pass to the clefts between the fingers, divide into two, 
which course along superficial to the corresponding arteries, 
and opposite the posterior extremity of the nail send dorsal 
branches around which ramify between the nail and its matrix, 
each nerve communicating with its fellow of the opposite side 
around both the palmar and the dorsal aspects. The ulnar 
nerve supplies the little finger and the inner side of the ring 
finger. 
Deep branch. The deep branch of the ulnar passes between 
the flexor minimi digiti and the abductor minimi digiti, runs 
along the palm of the hand accompanying the deep palmar arch, 
supplies the inner two lumbrical muscles, the interosseous 
muscles, the muscles of the hypothenar eminence, with the ex- 
ception of the palmaris brevis, and in the thenar group, sup- 
plies one muscle and a half, viz., the adductor pollicis, and the 
deep head of the flexor brevis pollicis, the remaining portion 
of the hand being supplied by the median nerve. 
The dorsal cutaneous branch of the ulnar arises three inches 
above the wrist joint, passes to the back of the forearm, and 
descends behind the styloid process of the ulna to the back of the 472 
DESCRIPTIVE ANATOMY. 
hand. Here it divides into cutaneous branches, the most in- 
ternal of which is distributed to the ulnar side of the little 
finger. The second passes to the cleft between the little and 
ring fingers, where it divides into dorsal collateral digital 
branches for these two fingers. The third cutaneous branch 
passes to the cleft between the ring and middle fingers, and, 
after receiving a communication from the radial, divides to 
supply the adjacent sides of these two fingers. These dorsal 
collateral digital branches communicate in the matrix of the 
nail with the palmar branches already noticed. 
Median. 
The median NERVE is the joint product of the internal and 
external cords of the brachial plexus; and derives fibres from 
all of the anterior cords entering into the formation of that 
plexus. It is formed at the commencement of the third por- 
tion of the axillary artery by the junction of a branch from the 
inner with a corresponding branch from the outer cord of the 
plexus. Formed on the front of the third portion of the axillary 
artery, it immediately drops to its outer side, and maintains 
that relation to the termination of the vessel. It then becomes 
an outer relation of the brachial artery, lying between that 
artery and the coraco-brachialis muscle. About opposite the 
insertion of the coraco-brachialis it passes to the front of the 
brachial artery, crossing it very obliquely, so as to remain on 
the front of that vessel for the middle one-third of its course. 
It then drops to the inner side of the brachial artery, and main- 
tains that relation to the termination of that vessel, a finger's 
breadth below the middle of the front of the elbow joint. It 
should here be noted that in case of high bifurcation of the 
brachial, the median nerve almost invariably passes between 
the two branches, the artery in front usually corresponding to 
the radial artery, and the one behind to the ulnar. In some 
cases the median nerve passes behind instead of in front of the 
brachial artery. 
Reaching the elbow joint it lies in the triangular space, the 
base of which is directed upward, and is formed by a line THE CENTRAL NERVOUS SYSTEM. 
473 
drawn from the inner to the outer condyle of the humerus, 
the external boundary being the supinator longus and the inner 
boundary the pronator radii teres. The nerve exactly bisects 
this space, passes between the two heads of. the pronator radii 
teres muscle, the deep head of which separates it from the 
ulnar artery. Crossing over the ulnar artery, and separated 
from it by the deep head of this muscle, it then passes down the 
middle of the front of the forearm, covered by the superficial 
head of the pronator radii teres and overlapped by the flexor 
carpi radialis on its outer side and the flexor sublimis digitorum 
on its inner side, and lying nearly directly behind the palmaris 
longus. It then passes to the front of the wrist joint, crosses 
beneath the anterior annular ligament into the palm of the hand, 
and breaks up into its terminal branches. 
Like the ulnar nerve it gives off no branches in the arm. 
It gives off a few small branches to the elbow joint; and just 
below the bend of the elbow gives off a large branch, called the 
anterior interosseous. 
The anterior interosseous nerve arises opposite the bicipital 
tubercle of the radius, runs downward on the interosseous mem- 
brane, accompanied by the anterior interosseous artery, as far 
as the upper border of the pronator quadratus muscle, where 
after giving branches to the deep surface of that muscle, it 
pierces the interosseous membrane and communicates with the 
posterior interosseous nerve. It supplies the deep muscles of 
the front of the forearm except the inner half of the flexor pro- 
fundus digitorum. 
Immediately below the elbow joint the median gives off 
branches to all the muscles of the superficial group on the 
front of the forearm with the exception of the flexor carpi 
ulnaris. 
In other words, it supplies muscular twigs to six and one- 
half out of eight of the muscles of the forearm, viz.: the pro- 
nator radii teres, flexor carpi radialis, palmaris longus, flexor 
sublimis digitorum, flexor longus pollicis, pronator quadratus, 
and outer one-half of the flexor profundus digitorium. 
Just before reaching the anterior annular ligament it gives 
off cutaneous branches, which are distributed to the integument 474 
DESCRIPTIVE ANATOMY. 
covering the thenar eminence of muscles, and which communi- 
cate with the superficial branch of the ulnar nerve, distributed 
to the hypothenar eminence. 
The remaining branches are divided into two sets. The first 
set supplies the superficial muscles of the thenar eminence, the 
abductor pollicis, the flexor ossis metacarpi pollicis, and the 
superficial head of the flexor brevis pollicis; or, in other words, 
all of the muscles which arise from the trapezium and the an- 
terior annular ligament, the remaining muscles of the group 
being supplied by the ulnar nerve. The other set divides into 
palmar collateral branches, of which the first two pass, one to 
the radial and the other to the ulnar side of the thumb on its 
palmar aspect, communicating with one another and with dorsal 
cutaneous branches, which will be described later. The third 
branch passes to the radial side of the index finger; the fourth 
to the cleft between the index and middle fingers; and the 
fifth, after receiving a communication from the ulna, passes 
to the cleft between the middle and ring fingers, and supplies 
the adjacent sides of those fingers, all of these branches com- 
municating with one another and also with the dorsal nerves. 
Musculo-Spiral. 
The musculo-spiral (n. radialis), the largest branch of the 
brachial plexus, arises from the posterior cord, and gets fibres 
from all of the cords of the brachial plexus, except the fifth. 
It passes downward as a posterior relation of the third portion 
of the axillary and of the first portion of the brachial artery. 
It then passes between the internal head of the triceps muscle 
and the shaft of the humerus, winding around the bone in the 
musculo-spiral groove, and at its junction of the lower third 
with the upper two-thirds of the shaft of the humerus, pierces 
the external inter-muscular septum, and appears in the inter- 
val between the brachialis anticus and the supinator longus. 
At the elbow joint, while still lying between these two muscles, 
it divides into its two terminal branches, the radial and the 
posterior interosseous. Before its division it gives off both 
cutaneous and muscular branches. THE CENTRAL NERVOUS SYSTEM. 
475 
Branches of the Musculo-Spiral 
Internal 
Radial 
Way- 
side 
Cutaneous 
Upper External 
Terminal 
Posterior 
Lower External 
Interosseous. 
Muscular 
The internal cutaneous branch is distributed to the skin cov- 
ering the middle of the back of the arm, and extends as far as 
the distribution of the nerve of Wrisberg, with which it com- 
municates. 
The upper external cutaneous pierces the external in- 
termuscular septum; and is distributed to the skin covering 
the outer portion of the biceps muscle. 
The lower external cutaneous branch pierces the external in- 
termuscular septum; and is distributed to the skin covering the 
supinator longus muscle, lying in the interval between the 
musculo-cutaneous nerve on its outer side, and the posterior 
branch of the internal cutaneous, on its inner side. 
The muscular branches are distributed to the three heads of 
the triceps muscle, a branch to the anconeous, which is a con- 
tinuation of the triceps, to the outer half of the brachialis anti- 
cus, supinator longus, and extensor carpi radialis longior; that 
is, to all of the muscles which take their origin above the ex- 
ternal condyle of the humerus. 
Radial. 
Of the two terminal branches of the median, the radial is 
purely a nerve of common sensation. It commences in the in- 
terval between the supinator longus, externally, and the bra- 
chialis anticus, internally. It then passes downward; and in 
the upper part of its course is a distant external relation to the 
radial artery. In the middle third it is a close external rela- 
tion of that vessel; but at the junction of the middle and lower 
thirds of the radius it passes beneath the tendon of the supinator 
longus and appears upon the back of the forearm, ceasing to be 
a relation of its artery. Emerging from beneath this tendon, 476 
DESCRIPTIVE ANATOMY. 
it becomes superficial, gives a branch which divides to supply 
the radial and ulnar sides of the thumb on their dorsal aspect, 
a second branch to the radial side of the index finger, a third, 
which divides to supply the adjacent sides of the middle and 
index fingers, and a fourth, which after receiving a communica- 
tion from the dorsal cutaneous branch of the ulna, divides to 
supply the adjacent sides of the middle and ring fingers. 
Posterior Interosseous. 
The posterior interosseous nerve, the second terminal 
branch of the musculo-spiral, commencing between the supinator 
longus and brachialis anticus, passes across the elbow joint to 
the supinator brevis muscle, and runs directly through the sub- 
stance of that muscle. It passes through the supinator brevis 
to the back of the forearm; runs downward on the posterior 
face of the interosseous membrane to reach the back of the 
wrist, where it has a small gangliform enlargement upon it, 
and receives a communication from the anterior interosseous 
branch of the median. Its distribution is to all of the muscles 
on the back of the forearm, with the exception of the anconeus, 
supinator longus, and extensor carpi radialis longior. The 
muscles supplied are the extensor carpi radialis brevior, the 
supinator brevis, the extensor communis digitorum, the exten- 
sor minimi digiti, the extensor carpi ulnaris, the extensor ossis 
metacarpi pollicis, the extensor primi internodii pollicis, ex- 
tensor secundi internodii pollicis, and the extensor indicis. 
The above description of this nerve, the usually accepted one, 
appears to be incorrect. It should be said that the musculo- 
spiral nerve supplies all the muscles on the back of the arm and 
forearm without using the useless term "posterior interosseous 
nerve;" and the radial should be described as a wayside branch 
of the nerve, as it really is. The above description is given in 
conformity with custom. THE CENTRAL NERVOUS SYSTEM. 
477 
Circumflex Nerve. 
The circumflex nerve is the last of the terminal branches 
of the brachial plexus. Arising from the posterior cord, in com- 
mon with the musculo-spiral, and receiving fibres from the 
fifth, sixth, seventh, and eighth cervical nerves, it passes down- 
ward on the subscapularis to the lower border of that muscle, 
being a posterior relation of the third portion of the axillary 
artery. It now passes to the back of the humerus, running 
through the quadrilateral interval bounded above by the teres 
minor, below by the teres major, internally by the long head 
of the triceps and externally by the shaft of the humerus. It 
accompanies the posterior circumflex artery. The nerve now 
divides into an upper and a lower branch-the upper to accom- 
pany the posterior circumflex vessels, winding around the sur- 
gical neck of the humerus, beneath the deltoid muscle, which it 
pierces, supplying that muscle and the skin over its lower part. 
The lower branch distributes filaments to the teres minor and 
back of the deltoid and pierces the deep fascia to reach the skin 
covering the lower part of the deltoid and the long head of the 
triceps. The nerve gives an articular filament to the shoulder 
joint. 
Dorsal Spinal Nerves. 
The dorsal spinal nerves are twelve pairs, the posterior 
branches of which are distributed to the structures of the back, 
while the anterior cords form the intercostal nerves, and, unlike 
other spiral nerves, do not form a plexus, but are distributed 
separately. 
Intercostal Nerves. 
The intercostal nerves are the anterior cords of the twelve 
dorsal nerves, and derive their name from their course forward 
between the ribs. 
The first dorsal nerve sends almost all its bulk to the brachial 
plexus, and the twelfth usually gives a branch to the lumbar 
plexus. The intercostal nerves are intended for the supply of 
the muscles among which they course, and of the integument 478 
DESCRIPTIVE ANATOMY. 
on the front and sides of the thorax and abdomen. Each in- 
tercostal nerve runs forward in the intercostal space between 
the intercostal muscles to near the edge of the sternum where 
it turns forward and becomes superficial, being called the an- 
terior cutaneous. It' is then distributed to the integument of 
the front of the chest and abdomen, most of the filaments pass- 
ing outward in a recurrent course. The six upper nerves appear 
as the anterior cutaneous through the corresponding intercostal 
spaces, while the six lower pierce the sheath of the rectus muscle, 
and are called the anterior cutaneous of the abdomen. After 
reaching the extremeties of the intercostal spaces these last 
nerves pass on between the broad muscles of the abdomen, and 
the last one, though called intercostal, is really not one since it 
lies below the last rib. Whilst running forward the intercostal 
nerves supply the intercostal muscles and the broad muscles of 
the abdomen, and about midway in its course each nerve gives 
off a branch called lateral cutaneous, which divides into two, 
one branch passing forward and the other backward, both being 
distributed to the integument on the side of the chest or ab- 
domen. The first intercostal nerve, owing to the fact that most 
of the cords from which it is derived go to the brachial plexus, 
gives off no lateral branch, and, to compensate for this delin- 
quency, the lateral cutaneous branch of the second nerve is re- 
markably large, and not only fulfils the office of the lateral 
cutaneous branches for itself and the first, but under the name 
of intercosto-humeral, passes into the axilla, where it com- 
municates with the lesser internal cutaneous. The lateral 
cutaneous branch of the twelfth nerve descends over the crest 
of the ilium, and is distributed to the integument of the gluteal 
region. 
Lumbar Spinal Nerves. 
The lumbar spinal nerves are five pairs, the posterior cords 
of which are distributed to the structures of the back, while the 
anterior form a plexus, called the lumbar plexus, the last cord 
of the lumbar nerves, however, passing downward to enter into 
the formation of the sacral plexus. THE CENTRAL NERVOUS SYSTEM. 
479 
Lumbar Plexus. 
The manner of formation of the lumbar plexus is generally 
as follows: The twelfth dorsal nerve gives a branch which de- 
scends in the substance of the psoas magnus muscle to unite 
with the first lumbar. The cord thus formed gives off the ilio- 
hypogastric and ilio-lumbar nerves, and a branch which de- 
scends to unite with the second lumbar. The second lumbar, 
after receiving this branch, gives off a branch of distribution, 
the genito-crural, and a communicating branch, which descends 
to unite with the third lumbar. Thus the genito-crural is the 
product of the first and second lumbar. The cord formed by the 
union of the branch from the second with the third lumbar 
nerve gives off an external cutaneous branch and a branch which 
unites with the fourth lumbar, conveying to that nerve some 
of the fibres derived from the second as well as the third. The 
union of these branches produces the anterior crural, which, 
therefore, contains fibres from the second, third, and fourth 
lumbar nerves, while the last nerve of the plexus, the obturator, 
is the product of the third and fourth. The remaining portion 
of the fourth unites with the last lumbar to form the lumbo- 
sacral cord, which passes down into the pelvic cavity to aid in 
the formation of the sacral plexus. 
The lumbar plexus resembles in the manner of its formation 
the cervical. It is situated in the posterior fibres of the psoas 
magnus muscle; and its branches, with the exception of the 
genito-crural, pass outward beneath the posterior surface of 
that muscle, the genito-crural perforating the muscle and ap- 
pearing upon its anterior surface. 
Branches of the Lumbar Plexus. 
Ilio-Hypogastric. 
External Cutaneous. 
Ilio-Inguinal. 
Genito-Crural (Femoral). 
Anterior Crural. 
Obturator. 
Muscular. 
Communicating. 480 
DESCRIPTIVE ANATOMY. 
The branches OF the lumbar plexus, named in the order 
in which they arise from above downward are the ilio-hypo- 
gastric, ilio-inguinal, genito-crural, external cutaneous, anterior 
crural, and obturator. Some authorities mention the accessory 
obturator, which is an infrequent branch. In addition to these 
the plexus also gives muscular branches, which supply the psoas 
magnus and quadratus lumborum muscles, and arise irregularly 
from the plexus. 
Ilio-Hypogastric. 
The ilio-hypogastric, the product of the first lumbar nerve, 
appears at the outer border of the psoas magnus, crosses the 
quadratus lumborum near the upper end of that muscle, pass- 
ing downward and outward, lying behind the peritoneum, 
pierces the transversalis muscle, and lies for a short distance 
between that muscle and the internal oblique until it reaches 
a point from two to two and one-half inches behind the anterior 
superior spinous process of the ilium, where it divides. 
The iliac branch, piercing successively the internal and ex- 
ternal oblique muscles, passes downward on the thigh toward 
the trochanter major, to be distributed to the integument. 
The hypogastric branch continues the direction of the main 
trunk, at first lying between the internal oblique and the trans- 
versalis, and then between the internal and external oblique 
muscles, finally piercing the aponeurosis of the external oblique, 
and becoming superficial, to be distributed to the integument 
over the lower portion of the abdomen. 
Ilio-Inguinal. 
The ilio-INGUINAL nerve arises from the first lumbar in com- 
mon with the ilio-hypogastric, and passes downward and out- 
ward, parallel with and below that nerve, across the quadratus 
lumborum muscle. After crossing the iliacus internus, it pierces 
the transversalis muscle; and between that muscle and the in- 
ternal oblique, communicates with the hypogastric branch of 
the ilio-hypogastric. It then becomes more superficial near the 
superficial abdominal ring, and leaving the abdominal cavity THE CENTRAL NERVOUS SYSTEM. 
481 
through that aperture, passes to the thigh, where it is distributed 
to the skin covering the inner, upper front aspect of the thigh, 
and to the scrotum in the male and to the labium in the female. 
Genito-Femoral. 
The genito-femoral is the product of the first and second 
lumbar nerves. It passes directly forward through the fibres 
of the psoas magnus muscle, and descends upon that muscle 
to just above Poupart's ligament, where it divides into a genital 
and a crural branch. 
The genital branch enters at the deep abdominal ring; and 
following the course of the spermatic cord, is lost in the male 
in the cremaster muscle, which it supplies. In the female this 
branch is rudimentary; but follows the course of the round 
ligament and is lost upon that structure. It crosses the ex- 
ternal iliac artery near the termination of that vessel. 
The crural branch passes beneath Poupart's ligament; and 
runs down on the thigh, to be distributed to the integument 
of its inner front aspect as far as the middle. It is an anterior 
relation of the femoral artery. 
External Cutaneous. 
The EXTERNAL cutaneous nerve is the product of the second 
and third lumbar nerves. It passes downward and outward 
across the iliacus internus muscle behind the peritoneum, and 
reaches the notch found below the anterior superior spinous pro- 
cess of the ilium. It here leaves the abdominal cavity, and lies 
beneath the fascia lata for the upper inch or two inches of its 
course. It then pierces the fascia lata, and becoming superficial, 
is distributed to the skin on the outer front aspect of the thigh, 
its distribution lying in the interval between the iliac branch 
of the ilio-hypogastric and the middle cutaneous branch of the 
anterior crural. Fibres from this nerve descend as far as the 
knee joint. 482 
DESCRIPTIVE ANATOMY. 
Obturator. 
The obturator nerve arises from the third and fourth lumbar 
nerves and occasionally receives fibres from the second lumbar. 
It passes beneath the psoas magnus muscle, runs over the brim 
of the pelvis, and crossing along just beneath the pelvic brim, 
where it lies above the obturator vessels, reaches the upper 
angle of the thyroid foramen, and piercing that foramen it 
divides into two branches, an anterior and a posterior. The 
anterior branch is distributed to the hip joint, to the adductor 
longus, adductor brevis, the gracilis, sometimes to the pectineus, 
and has a cutaneous branch which passes to the skin of the 
inner side of the thigh. The posterior branch also drops a twig 
to the hip joint, and supplies the obturator externus and adduc- 
tor magnus muscle. 
Femoral or Anterior Crural. 
The anterior crural (femoral) nerve is the largest branch 
of the lumbar plexus; and receives fibres from the second, third, 
and fourth lumbar nerves. It passes downward in the interval 
between the psoas magnus and iliacus internus muscles, and 
runs beneath Poupart's ligament, where it lies from one-fourth 
to one-half an inch to the outer side of the femoral artery. 
After descending for a very short distance, rarely more than 
one inch and generally about half an inch, it divides into 
branches, which are usually described as superficial, or cutane- 
ous, branches, and deep, or muscular branches. 
Superficial Branches. 
Middle Cutaneous. 
Internal Saphenous. 
Internal Cutaneous. 
Middle Cutaneous. 
The middle cutaneous branch passes forward superficial to 
the femoral artery; and is distributed to the integument which THE CENTRAL NERVOUS SYSTEM. 
483 
covers the front of the thigh lying between the internal cutane- 
ous and the external cutaneous, which is a direct branch of the 
lumbar plexus, and communicating with both of these nerves. 
The middle cutaneous generally perforates the sartorius muscle, 
and in doing so, gives off branches which supply that muscle. 
Internal Cutaneous. 
The internal cutaneous is smaller than the middle cutane- 
ous. It passes inward in front of the femoral artery, and divid- 
ing into an anterior and a posterior branch, passes to the inner 
side of the thigh. 
The anterior branch communicates with the middle cutaneous, 
while the posterior branch runs along the edge of the sartorius 
muscle, pierces the fascia lata, and is distributed to the integu- 
ment of the inner side of the thigh as low down as the knee 
joint, communicating in its course with the cutaneous branch 
of the obturator nerve. 
Internal, or Long, Saphenous. 
The internal, or long, saphenous nerve descends in close 
contact with the outer side of the sheath of the femoral vessels 
until it reaches Hunter's canal, where it becomes superficial to 
these vessels. In the upper portion of its course it is in close 
relationship with the muscular branch to the vastus internus 
muscle, the two nerves bearing almost exactly the same relation 
to the femoral artery, with the saphenous slightly in front. At 
Hunter's canal the nerve sometimes passes in front of that 
fibrous structure, and is separated by it from the front of the 
femoral artery; but it usually lies on the femoral artery in 
Hunter's canal, but not in the femoral sheath. At the lower 
extremity of Hunter's canal the nerve passes beneath the tendon 
of the sartorius muscle, and accompanies that muscle downward 
to its insertion, where it pierces the insertion between the sar- 
torius and the gracilis to become superficial just below the 
knee. It now comes into relationship with the internal saphe- 
nous vein, and accompanies that vessel down the inner side of 484 
DESCRIPTIVE ANATOMY. 
the leg to pass in front of the internal malleolus, and then to 
continue its course onward to the inner side of the great toe, 
which it supplies. 
It gives off throughout its course cutaneous branches, which 
are distributed throughout the course of the nerve. At the 
knee joint it gives one large branch, the cutaneous nerve of the 
patella, which pierces the sartorius, and running downward and 
outward, aids in the formation of the patella plexus. 
Deep, or Muscular, Branches. 
The deep, or muscular, branches are nerves to the iliacus 
internus, given off while the anterior crural is in the abdominal 
cavity; branches to the pectineus (usually two in number, though 
sometimes but one) which pass behind the femoral vessels; a 
separate branch occasionally to the sartorius, though that muscle 
is usually supplied by the middle cutaneous; several short 
branches to the vastus extemus, which enter its upper portion; 
a branch which enters the deep surface of the rectus; and a 
long branch, already mentioned, the nerve to the vastus internus, 
which is in close relationship to the femoral artery and the 
internal saphenous nerve, enters the vastus internus just above 
Hunter's canal. 
It will be seen, therefore, that the anterior crural nerve, by 
means of one of its superficial branches, the middle cutaneous, 
supplies one of the muscles of the front of the thigh, the sar- 
torius; while the two vasti and the rectus are supplied by deep 
branches of the anterior crural. The one remaining muscle on 
the front of the thigh, the tensor vaginae femoris, is supplied by 
a branch from the sacral plexus of nerves. 
The Lumbo-Sacral Cord. 
The last branch of the lumbar plexus is a communicating 
branch, called the lumbo-SACRAL cord. This cord is the joint 
product of the fifth lumbar nerve with a branch from the fourth; 
and passes over the brim of the pelvis to unite with the first 
sacral nerve, commencing the formation of the sacral plexus. THE CENTRAL NERVOUS SYSTEM. 
485 
The Sacral Plexus. 
The sacral plexus itself is the product of the lumbo-sacral 
cord, with the first, second, third, and half of the fourth sacral 
nerves. The fibres entering into this plexus are more intimately 
united than in any other nervous plexus of the body. It is 
triangular in outline, the base of the triangle extending to the 
anterior sacral foramina, the apex being directed downward 
and outward to the great sacro-sciatic foramen. 
The lumbo-sacral cord, passing behind the common iliac 
artery, unites with the first sacral nerve, then at a short dis- 
tance from the anterior spinal foramina the second sacral unites 
with this cord, then the third, and lastly the upper half of the 
fourth, so that while lying upon the pyriformis muscle the sacral 
plexus consists of but a single, broad triangular cord, there 
being no such communication, followed by subdivision, as there 
is in the case of the brachial plexus. 
The plexus, after being formed in this way, extends down- 
ward and outward to the upper margin of the great sciatic fora- 
men, lying upon the pyriformis muscle, having the internal iliac 
artery in front of it, some branches of which vessel pass between 
the cords entering into the formation of the plexus and having 
the first portion of the rectum resting upon the cords as they 
emerge from the sacral foramina. On the left side, though sepa- 
rated from it by the peritoneum, the end of the sigmoid flexure 
of the colon would also rest upon the front of this plexus. 
Branches of the Sacral Plexus. 
Wayside. 
Terminal. 
Muscular. 
Gluteal. 
Internal Pudic. 
Visceral. 
Lesser Sciatic. 
Great Sciatic. 
Besides its terminal branches, this plexus also gives off cer- 
tain wayside, or collateral, branches which are distributed to 
the muscles and viscera in the pelvic cavity. The muscular 
branches come in part from the plexus and in part from the 
cords before they unite to form the plexus. They supply the 486 
DESCRIPTIVE ANATOMY. 
pyriformis, obturator internus, the gemelli and the quadratus 
femoris. 
The terminal branches are the gluteal, internal pudic, lesser 
sciatic, and great sciatic nerves. 
Gluteal. 
The GLUTEAL or SUPERIOR GLUTEAL nerve, as it is frequently 
called, arises from the upper portion of the sacral plexus, and 
leaves the pelvic cavity by passing above the pyriformis muscle 
through the greater sacro-sciatic foramen. It then appears in 
the interval between the gluteus medius and the gluteus mini- 
mus muscle, where it divides into two branches, superior and 
inferior. The superior follows the origin of the gluteus minimus, 
and is supplied to the gluteus medius from the under surface 
of that muscle, while the inferior passes downward, forward, 
and outward, distributing fibres to the gluteus minimus, its ter- 
minal branch ending in the tensor vaginae femoris. 
Internal Pudic. 
The internal pudic nerve arises from the lower part of the 
sacral plexus, leaves the pelvic cavity through the greater sacro- 
sciatic foramen, below the pyriformis, crosses the spine of the 
ischium, and re-enters the pelvic cavity through the lesser 
sciatic foramen. It then courses along the internal face of the 
ischium about an inch above its tuberosity, passes to the ramus 
of the ischium, and is enclosed in the fibrous sheath called 
Alcock's canal. It then passes between the two layers of the 
perineal fascia, and terminates by dividing into two branches, 
an upper one, the nerve to the dorsum of the penis, and an in- 
ferior branch, called the perineal. 
Prior to this division the internal pudic nerve gives off an 
inferior hemorrhoidal branch, corresponding to the artery of the 
same name, which is distributed to the sphincter ani muscle 
and to the integument around the anus. THE CENTRAL NERVOUS SYSTEM. 
487 
Terminal Branches of the Internal Pudic. 
Dorsalis Penis. 
Perineal. 
Dorsalis Penis. 
The dorsalis penis nerve, the branch to the back of the penis, 
passes upward and forward along the ramus of the ischium 
and pubis, accompanying the artery of the same name, pierces 
the suspensory ligament of the penis, and runs forward upon 
that organ to be distributed to the integument that covers it 
and to the corpus cavernosum, while its terminal branches end 
in the glans penis. In its course along the back of the penis it 
gives off lateral cutaneous branches, which are distributed to 
the skin upon the sides of the organ. 
Perineal. 
The perineal nerve, the second branch of the internal pudic, 
divides into two sets of branches, superficial and deep, or cuta- 
neous and muscular. 
The cutaneous branches are two, anterior and posterior, and 
pass upward and forward, to be distributed to the scrotum, 
perineum, and under surface of the penis, in which latter situa- 
tion they communicate with the dorsal nerve of the penis. In 
the female of course the upper of these two branches would be 
distributed to the labia ma j ora, the analogue of the scrotum 
in the male. 
The muscular branches are distributed to the muscles of the 
perineum; that is, the transversus perinei, erector penis, acceler- 
ator urinae and compressor urethrae, these names being given to 
the muscles in the male subject, each having its analogue in the 
female. That branch which passes to the transversus perinei 
corresponds to the transverse perineal artery. Some deep 
branches of this nerve also enter the corpus spongiosum, and 
supply that body, with its attached muscles. 488 
DESCRIPTIVE ANATOMY. 
Lesser Sciatic. 
The lesser sciatic nerve usually arises by two roots. It 
passes from the pelvic cavity through the greater sacro-sciatic 
foramen below the pyriformis muscle, and runs down opposite 
the middle of the interval between the trochanter major and the 
tuberosity of the ischium, lying beneath the gluteus maximus^ 
muscle. It emerges from the lower border of this muscle; and 
pursuing its course down the back of the thigh, beneath the 
fascia lata, reaches the superior angle of the popliteal space, 
where it breaks up into its terminal branches, which, after 
being distributed to the skin covering the popliteal space, com- 
municate with the cutaneous branch from the great sciatic and 
with the plexus around the patella. 
This nerve is almost entirely a cutaneous branch, except for 
the set of fibres which enters the gluteus maximus muscle, that 
muscle receiving its nerve supply entirely from the sacral plexus, 
most of the fibres passing to it from the inferior gluteal while 
a few fibres come from the lesser sciatic. The latter branches 
emerge from below the lower border of the muscle, and then 
reverse their course to enter it from its deep surface. 
The cutaneous branches are distributed to the skin on the 
back of the thigh as far down as the popliteal space. One 
branch of large size is individualized as a separate nerve, called 
the inferior pudendal. 
The inferior pudendal curves forward, running below the 
tuber ischii, passes to the scrotum in the male and the labium 
in the female, communicating with the superficial perineal and 
the terminal branch of the inferior hemorrhoidal. 
Inferior Gluteal. 
The inferior gluteal is intimately blended with the lesser 
sciatic until after its emergence from the great sciatic notch 
below the pyriformis muscle. It quickly breaks into a number 
of branches which enter the deep surface of the gluteus maxi- 
mus near its lower border. THE CENTRAL NERVOUS SYSTEM. 
489 
The Great Sciatic. 
The great sciatic is the longest and largest nerve in the 
body. It appears to be, and in reality is, a continuation of the 
sacral plexus. Triangular at its commencement, it soon be- 
comes circular in form. It emerges from the pelvic cavity below 
the pyriformis muscle through the greater sacro-sciatic fora- 
men, being the last of the numerous cords which emerge from 
this foramen. These structures are eight in number. Two 
of them pass above the pyriformis, and the remaining six below 
that muscle. Those which pass above the pyriformis are the 
superior gluteal nerve and the gluteal artery; those passing 
below it are the internal pudic, the lesser sciatic and great sciatic 
and inferior gluteal nerves, the internal pudic and ischiatic, 
or sciatic arteries. This does not complete the total number of 
structures which pass through this foramen, because in addi- 
tion should be mentioned the pyriformis muscle itself and the 
companion veins of the arteries named. 
After escaping from the pelvis, the great sciatic nerve passes 
down the middle of the back of the thigh, crossing the quadratus 
femoris, then resting on the adductor magnus muscle, and cov- 
ered by the muscles which arise from the tuberosity of the 
ischium. Two of these muscles, the semi-tendinous and semi- 
membranosus, quickly pass to its inner side, while the biceps 
covers the nerve for some distance down the thigh. At the 
upper angle of the popliteal space (formed externally by the 
biceps and internally by the semi-tendinosus and semi-mem- 
branosus muscles) the nerve appears between these muscles, 
called the "ham-string" muscles. It then passes into the pop- 
liteal space, and divides into its two terminal branches, the 
internal and external popliteal nerves. 
The point of division is variable, and may exist anywhere 
between the sacral plexus and the centre of the popliteal space. 
In a few rare cases the internal and external popliteal nerves 
come off separately from the sacral plexus; and in such cases 
they are sometimes separated from one another by the fibres 
of the pyriformis muscle. In other cases the division takes 
place below the tuberosity of the ischium, and in still other 490 
DESCRIPTIVE ANATOMY. 
cases at the middle of the popliteal space. As the nerves are 
bound together simply by connective tissue, the dissector may 
split them up to any point between the popliteal space and the 
sacral plexus. 
The point of termination usually given for the great sciatic 
is the superior angle of the popliteal space; but it rarely divides 
before reaching a lower point, so that the great sciatic itself, 
instead of its internal popliteal branch, is a relation of the 
popliteal artery at its upper part. 
Before dividing into terminal branches, the great sciatic 
gives off branches to supply the hip joint, the posterior femoral 
group, cutaneous branches which communicate with the lesser 
sciatic nerve, and a branch to the adductor magnus. 
Terminal Branches of the Great Sciatic. 
Internal Popliteal. 
External Popliteal. 
Internal Popliteal. 
The internal popliteal nerve, the larger of the two terminal 
branches of the great sciatic, commences below the upper angle 
of the popliteal space, passes through that space, and terminates 
by becoming the posterior tibial nerve. As it enters at the 
apex of the popliteal space, it necessarily lies to the outer side 
of, and superficial to, the popliteal artery and vein; but the 
nerve has an inclination inward, while the inclination of the 
artery is outward, hence at the middle of the popliteal space, 
opposite the posterior ligament of the knee joint, the nerve 
is found directly behind the artery, with the vein interposed 
between itself and the artery, while at the termination of the 
popliteal space both nerve and vein have become internal to the 
artery, the vein still lying between the nerve and the artery. At 
the lower border of the popliteus muscle, at a point which cor- 
responds to the junction of the upper one-fifth with the lower 
four-fifths of the shaft of the tibia, the internal popliteal nerve 
terminates by changing its name to the posterior tibial. THE CENTRAL NERVOUS SYSTEM. 
491 
The nerve, like the other important structures contained in 
this diamond-shaped space, has the internal ham-string muscles 
to its inner side above, and the inner head of the gastrocnemius 
below, while to its outer side are, above, the biceps, and below, 
the outer head of the gastrocnemius and the plantaris muscles. 
It is covered by the strong fascia which extends between these 
muscles and roofs in the entire space. 
Branches of the Internal Popliteal. 
Articular. 
Muscular, or Sural. 
Cutaneous. 
The branches of the internal popliteal are divided into 
three sets, articular, muscular, and cutaneous. 
The articular branches are three in number; and are known 
as superior and inferior internal articular, and azygos articular. 
They accompany the arteries of the same name; and are distri- 
buted in the same way. They communicate with one another, and 
with the other nerves which surround the knee joint, passing 
as far as the patella plexus, while the azygos articular, piercing, 
with the corresponding artery, the posterior ligament of the 
knee, is distributed to the synovial membrane in the interior 
of that joint. 
The muscular, or sural (L. sura, the calf of the leg), branches 
accompanying the sural branches of the popliteal artery, are dis- 
tributed to the two heads of the gastrocnemius, the soleus and 
the plantaris muscle. In addition to these sural branches, the 
internal popliteal nerve gives off the branches which supply 
the popliteus muscle. These branches, two in number, pass 
down to the lower border of the popliteus muscle, and, reversing 
their course, pass upward between that muscle and the posterior 
surface of the interosseous membrane, to enter the muscle from 
its deep face. 
The only cutaneous branch, the communicans poplitei, passes 
downward in the interval between the two heads of the gastroc- 
nemius muscle, lies in the groove upon the posterior surface of 
the belly of that muscle, accompanied by the external saphenous 
vein; and, about middle of the calf of the leg, is joined by a 492 
DESCRIPTIVE ANATOMY. 
branch of communication from the external popliteal nerve, 
called the communicans peronei, thus forming the external 
saphenous nerve. After receiving this branch it continues down- 
ward, with a slight inclination outward, passes behind the ex- 
ternal malleolus, and reaching the dorsum of the foot, is dis- 
tributed to the integument on the back of the leg, the outer, 
back part of the ankle, and the outer side of the foot as far 
as the little toe, where it communicates with a branch of the 
musculo-cutaneous nerve. 
Posterior Tibial. 
The posterior tibial nerve is a continuation of the internal 
popliteal, and commences where that nerve terminates at the 
lower border of the popliteus muscle. It at first lies to the 
inner side of the posterior tibial artery; but about two inches 
below the origin of that vessel, crosses it superficially opposite 
the origin of the personeal branch, and lies for a short distance 
in the interval between the peroneal and posterior tibial arteries. 
It then descends to the outer side of the posterior tibial, and 
remains a continuous external relation of that vessel to its ter- 
mination, but lies on a plane posterior to it. 
It divides midway between the inner malleolus and the pos- 
terior tuberosity of the os calcis into the internal and external 
plantar branches. 
Wayside Branches. 
The branches of the posterior tibial nerve are muscular 
branches, which supply the tibialis posticus, flexor longus pol- 
licis, and the flexor longus digitorum. At the ankle joint, how- 
ever, it gives off an articular branch to the ankle and calcanean 
branches, which, accompanying the corresponding arteries, are 
distributed to the skin on the inner aspect of the heel. 
Terminal or Plantar. 
Internal Plantar. 
External Plantar. THE CENTRAL NERVOUS SYSTEM. 
493 
The internal and external plantar nerves differ from one 
another, and more distinctly from the internal and external 
plantar arteries, because while the internal plantar artery is 
smaller in size than the external, and has a less extended dis- 
tribution, the internal plantar nerve is larger than the external. 
The internal plantar nerve corresponds in a general way in its 
distribution to the median nerve of the hand; while the external 
plantar corresponds to the ulnar nerve in the hand. That is, 
the internal plantar nerve supplies three toes and a half, equal 
to the three and one-half fingers of the median; while the ex- 
ternal plantar supplies one toe and a half, the equivalent of the 
ulnar of the hand. 
Internal Plantar. 
The internal plantar nerve passes forward as the com- 
panion of the internal plantar artery, supplies the inner half 
of the flexor brevis digitorum, then continuing its course it gives 
a branch to the abductor pollicis and to the inner two lumbrical 
muscles, and to the flexor brevis pollicis and articular branches 
to the tarsus and metatarsus. 
It then divides into its terminal branches, the most internal 
of which passes to the inner side of the great toe, the second to 
the cleft between the second and great toe, where it divides into 
branches for the adjacent sides of these two toes, the third to 
the cleft between the second and third toes, and the fourth, 
after giving off a branch of communication to the external plan- 
tar, runs to the cleft between the third and fourth toes and 
supplies the adjacent sides of these toes. 
External Plantar. 
The external plantar nerve accompanies the external plan- 
tar artery, passes beneath the origin of the flexor brevis digi- 
torum, and lies between that muscle and the abductor minimi 
digiti. It then runs forward as far as the posterior extremity 
of the fifth metatarsal bone. It then plunges beneath the second 
layer of muscles on the sole of the foot, and accompanies the 494 
DESCRIPTIVE ANATOMY. 
arch formed by the external plantar artery. In this course it 
supplies the abductor minimi digiti, the outer half of the flexor 
brevis digitorum, the flexor accessorius, and the outer two lum- 
bricals, and gives branches to the interosseous muscles. As it 
passes between the second and third layers of the foot it supplies 
all the muscles of the third layer of the sole except the flexor 
brevis pollicis. Its digital branches are given off near the base 
of the fifth metatarsal bone, one to the outer side of the little 
toe, and one, which after communicating with the internal plan- 
tar, divides at the cleft between the fourth and fifth toes and 
supplies the adjacent sides of these toes. 
External Popliteal. 
The external popliteal nerve begins as a branch of the 
great sciatic, near the upper angle of the popliteal space, passes 
downward and outward and is only momentarily a relation of 
the popliteal artery, lying superficial to it and to its outer 
side. It then passes behind the external tuberosity of the femur, 
crosses the head of the fibular, and plunging into the substance 
of the peroneus longus muscle, terminates there by dividing 
into the anterior tibial and the musculo-cutaneous nerves. The 
relation of this nerve to the popliteal artery is, as before men- 
tioned, only momentary, except in those cases in which the nerve 
is so closely bound to the internal popliteal as to diverge from 
that nerve at the middle of the popliteal space. 
Branches. 
Way- 
side 
Articular. 
Terminal 
Anterior Tibial. 
Communicans Peronei. 
Musculo-Cutaneous. 
In all cases the external popliteal nerve gives off two articular 
branches corresponding to the superior external and inferior 
external articular arteries, these branches accompanying the 
arteries and being distributed in the same way. A recurrent 
articular branch is also given off which accompanies the ante- 
rior tibial recurrent artery and supplies the front of the knee. THE CENTRAL NERVOUS SYSTEM. 
495 
The Communicans Peronei. 
Below the knee-joint the external popliteal gives off the COM- 
municans peronei, which unites with the communicans pop- 
litei to form the external saphenous nerve and to be distributed 
with that nerve. 
The Anterior Tibial. 
Of the two terminal branches of the external popliteal the 
anterior tibial, after passing through the fibres of the pero- 
neus longus, lies between that muscle and the extensor longus 
digitorum. It then passes to the front of the interosseous mem- 
brane, having passed obliquely beneath the extensor longus 
digitorum, and becomes a relation of the anterior tibial artery, 
having the same muscular relations as that vessel; viz., for the 
upper third to its outer side is the extensor longus digitorum, 
to its inner side the tibialis anticus; in the middle third the 
extensor proprius pollicis to the outer side and the tibialis an- 
ticus still to the inner side; in the lower third it has the ex- 
tensor longus digitorum to the outer side and the extensor 
proprius pollicis to the inner side, which muscle has crossed to 
the front of the nerve and displaced the tibialis anticus. To 
the artery it bears a triple relation, lying first to the outer 
side and resting on the interosseous membrane, then for the 
middle third of the anterior tibial artery the nerve rests on 
its front, separated by the artery from the interosseous mem- 
brane, and in the lower third of the vessel the nerve drops to 
the outer side, and maintains that relation to the front of the 
ankle join. 
At the front of the ankle joint the nerve passes beneath the 
anterior annular ligament, but does not change its name as the 
artery does. To the dorsalis pedis artery it maintains the same 
relation which it bore to the anterior tibial, lying on the outer 
side of that vessel. It continues as far as the cleft between the 
great and second toes, where it divides into two branches to 
supply the adjacent sides of these two toes, after having com- 
municated with the long saphenous branch of the anterior crural 496 
DESCRIPTIVE ANATOMY. 
nerve on the inner side of the great toe, its outer branch com- 
municating with the musculo-cutaneous. 
Branches. 
The anterior tibial nerve in its course over the leg supplies 
branches to the tibialis anticus, extensor longus digitorum, and 
extensor proprius pollicis, while at the ankle it has a gangliform 
enlargement which corresponds to that on the posterior inter- 
osseous of the forearm from which are given off branches to 
supply the flexor brevis digitorum muscle and the tarsal and 
metatarsal articulations. 
Musculo-Cutaneous. 
The musculo-cutaneous nerve, after being formed by the 
division of the external popliteal, passes downward, first in 
the fibres of the peroneus longus muscle, then in the interval 
between that muscle and the peroneus brevis, then between 
the two peronei muscles and the extensor longus digitorum, 
Running down on the front of the external malleolus, it passes 
to the dorsum of the foot, where it breaks up into cutaneous 
branches to supply all the toes from the outer face of the second 
toe to the inner face of the little toe, and gives a twig to the 
inner side of the great toe. 
In its course through the leg it gives off branches which sup- 
ply the peroneal muscles. As it passes the external malleolus 
it gives a branch which corresponds to the external malleolar 
branches of the anterior tibial artery; and these branches are 
distributed to the skin on the outer aspect of the ankle. 
The distribution of the nerve on the dorsum of the foot is 
very irregular. The most frequent arrangement is that it com- 
municates on the outer side of the little toe with the external 
saphenous nerve, then gives a branch which passes to the cleft 
between the fifth and the fourth toes and supplies them, a third 
branch to the cleft between the fourth and third toes, and a 
fourth branch to the cleft between the third and second toes- 
which branch communicates with the anterior tibial nerve,- THE CRANIAL NERVES. 
497 
and a branch to the inner side of the great toe which com- 
municates with the long saphenous. 
It will be seen that the distribution of the nerves on both the 
back of the hand and the back of the foot is quite as irregular 
as the distribution of the arteries in the same situation. In 
some instances the anterior tibial nerve has been seen to supply 
the great, the second, and half of the third toe; and, in other 
cases, the musculo-cutaneous supplies the little, fourth, third, 
and second toes; while in but few cases have I been able to trace 
the internal saphenous to the extremity of the great toe, or the 
external saphenous to the extremity of the little toe. 
THE CRANIAL NERVES. 
The CRANIAL NERVES comprise twelve pairs, one on each side, 
those of one side having their counterpart on the other. 
The definition of a cranial nerve is that it appears at the 
base of the brain and emerges through an aperture in the skull. 
The point on the base of the brain where the nerve appears 
is called its apparent origin, since it may be traced into the 
interior of the brain to what is called its real, or deep, origin. 
The cranial nerves are named numerically, in pairs, from be- 
fore backward; besides which each pair is known by another 
or, in some cases, several other names derived from the part to 
which the nerve is distributed. The following table gives the 
synonyms of the twelve pairs: 
First Pair, Olfactory. 
Second Pair, Optic. 
Third Pair, Motores Oculorum. 
Fourth Pair, Pathetic (Trochleares). 
Fifth Pair, Trifacial (Trigeminus). 
Sixth Pair, Abducentes. 
Seventh Pair, Facial (Portio Dura). 
Eighth Pair, Auditory (Portio Mollis). 
Ninth Pair, Glosso-Pharyngeal. 
Tenth Pair, Pneumogastric, Par Vagum, Vagus. 
Eleventh Pair, Spinal Accessory. 
Twelfth Pair, Hypoglossal. 498 
DESCRIPTIVE ANATOMY. 
These twelve pairs were formerly considered as only nine 
from the fact that, as will be seen, they emerge through nine 
foramina of the cranium at the base. The classification into 
nine pairs is known as that of Willis and the one just given 
as that of Sommerring. The two classifications are similar for 
the first six pairs, the seventh pair, in Willis' classification, con- 
sisted of the seventh and eighth, while the eighth consisted of 
the glosso-pharyngeal, pneumogastric and spinal accessory, and 
the ninth of the hypoglossal. 
A general outline of the cranial nerves successively, from 
their apparent origin to their point of emergence, will first be 
given and afterwards each pair will be taken up and described. 
The first seen on the base of the brain from before backward 
is the first pair. The first nerve lies on the under surface of 
the anterior lobe of the cerebrum in a groove a little external 
to the longitudinal fissure, having its commencement by a three- 
forked origin just in front of the anterior perforated space. 
Near the anterior extremity of the anterior cerebral lobe it 
enlarges into an oval-shaped mass which lies upon the cribri- 
form plate of the ethmoid bone and sends its branches of dis- 
tribution through the foramina seen there. 
The second nerve is first seen under the name of the optic 
tract, approaching its fellow from the outer aspect of the crus 
cerebri and passing beside the tuber cinereum and uniting in 
front of it with its fellow to form the optic chiasm or commissure 
from which the two optic nerves diverge forward to enter the 
orbits through the optic foramina. 
The third nerve is seen emerging to the inner side of the crus 
cerebri, just in front of the pons Varolii, and runs forward to 
leave the cranium through the anterior lacerated foramen. 
The fourth nerve has its apparent origin external to the third, 
on the optic side of the crus cerebri, and also has its exit through 
the anterior lacerated foramen. 
The fifth is the largest of the cranial nerves and is first seen 
just behind the origin of the fourth. It pierces the lateral aspect 
of the pons Varolii and splits into three portions, ophthalmic, 
superior and inferior maxillary, which require three apertures THE CRANIAL NERVES. 
499 
of exit from the cranium. The ophthalmic leaves through the 
anterior lacerated foramen, the superior maxillary through the 
foramen rotundum, the inferior maxillary through the fora- 
men ovale. 
The sixth nerve takes its apparent origin behind that of the 
fifth from the upper constricted portion of the medulla ob- 
longata, just behind the pons Varolii, and passes forward to gain 
egress through the anterior lacerated foramen, which is thus 
seen to transmit three entire cranial nerves, viz., third, fourth, 
and sixth, and a part of another, viz., the ophthalmic branch 
of the fifth. 
The seventh, eighth, ninth, tenth and eleventh all arise in 
the order named, from above downward, in the groove between 
the corpora olivare and restiformia of the medulla oblongata. 
The seventh and eighth leave the cranium through the same 
opening, the internal auditory meatus, while the ninth, tenth 
and eleventh all gain exit through the posterior lacerated fora- 
men. 
The twelfth has its apparent origin to the inner side of the 
five preceding nerves, from the groove between the corpora 
olivare and pyramidale, by numerous filaments which are 
speedily collected into two cords, which unite to form the nerve 
as it emerges through the anterior condyloid foramen. 
The First Nerve. 
The first, or olfactory, nerve arises by three forks or roots, 
close to the anterior perforated space. The external, or long, 
root consists of white fibres and may be traced along the fissure 
of Sylvius into the middle lobe of the cerebrum; the middle 
root is of gray matter and springs from the posterior part of 
the anterior lobe; the inner, or short root is of white fibres, 
and also arises from the posterior part of the anterior 
lobe. The three roots unite to form the nerve, just in 
front of the anterior perforated space, which passes for- 
ward, triangular in shape and grayish in color, lying in a groove 
on the under surface of the anterior lobe of the cerebrum a 
little external to the longitudinal fissure. The nerve swells into 500 
DESCRIPTIVE ANATOMY. 
an oblong, grayish enlargement, called the bulbus olfactorius, 
which lies beside the crista galli on the cribriform plate of the 
ethmoid bone. From the under surface of the olfactory bulb 
are given off some twenty filaments, which descend into the 
nose through the foramina of the cribriform plate to be dis- 
tributed to the mucous membrane of the nose as far down as 
the middle turbinated bone. These filaments are arranged in 
three sets, viz., those to the septum, those to the external wall 
and those to the roof of the nose. 
Second Nerve. 
The SECOND, or optic, nerve has its apparent origin just ex- 
ternal to the crus cerebri, whence it may be traced to its deep, 
or real, origin from various parts of the optic thalamus and 
from the corpora quadrigemina. Winding around the outer 
side of the crus cerebri, it passes forward and inward beside the 
tuber cinereum and in front of it unites with its fellow to form 
the optic commissure or chiasm. The tract is divided into two 
bands of which the external joins the outer geniculate body and 
pulvinar; while the internal, after connecting with the inner 
geniculate body, loses itself in the brachium. The portion ex- 
tending from the origin to the optic chiasm is called the optic 
tract. From the optic chiasm the two optic nerves diverge 
anteriorly to enter the orbit through the optic foramina, each 
piercing the sclerotic and choroid coats of the eye-ball to ex- 
pand into the retina. 
The connection between the optic tract, chiasm, and nerve 
is as follows: The optic tract is composed of filaments, the 
outermost of which pass into the nerve of that side, while the 
innermost curve over, through the chiasm, to form the inner- 
most fibres of the opposite tract, and the middle fibres of the 
tract of one side pass through the chiasm to form the middle 
fibres of the nerve of the opposite side. THE CRANIAL NERVES. 
501 
Third Nerve. 
The third nerve, or motor oculi, leaves the brain just to 
the inner side of the crus, near the front of the pons. The 
deep origin can be traced through the locus niger and teg- 
mentum to a nucleus beneath the floor of the aqueduct of Syl- 
vius. It pierces the dura below and to the outer side of the 
posterior clinoid process. It then passes forward lying in the 
outer wall of the cavernous sinus, with the fourth and oph- 
thalmic division of the fifth below and external to it, and the 
sixth internal and separating the third from the internal carotid. 
Continuing its course the nerve reaches the anterior lacerated 
foramen, or sphenoidal fissure, and splits into two divisions. 
Both divisions enter the orbit, passing between the two heads 
of the external rectus muscle and being separated from each 
other by the nasal nerve. In the sphenoidal fissure the third 
lies on the lower wall of the fissure with the nasal and the 
sixth, the upper division of the third being most external, then 
the nasal, lower division of the third and sixth in the order 
named. The terminal branches are now given off, the nerve 
supplying all the muscles of the ocular group except the ex- 
ternal rectus and the superior oblique. The upper division, 
which passes above the optic nerve, supplies the superior rectus 
and the levator palpebrse. The lower division passes beneath 
the optic nerve and supplies the inferior and internal recti and 
the inferior oblique. 
While lying in the cavernous sinus the nerve communicates 
with the cavernous plexus. Sometimes the superior division 
receives a communication from the nasal; while the branch to 
the inferior oblique gives off the motor root of the ciliary 
ganglion. The branches to the muscles enter on their deep or 
ocular surface. 
Fourth Nerve. 
The fourth, or patheticus, appears just external to the ap- 
parent origin of the third on the outer surface of the crus 
cerebri. Its deep origin is a nucleus on the floor of the aqueduct 
of Sylvius. After winding around the crus cerebri the fourth 502 
DESCRIPTIVE ANATOMY. 
pierces the dura below the posterior clinoid process and runs 
forward in the sinus with the third above and the ophthalmic 
division of the fifth below it. On reaching the sphenoidal fis- 
sure the fourth passes through that fissure at its highest and 
most internal point. On reaching the orbit it crosses over the 
origin of the levator palpebrae and enters the superior oblique 
on the orbital surface of that muscle. It communicates with the 
cavernous portion of the sympathetic and gives off a small and 
unimportant branch to the tentorium. 
Fifth Nerve. 
The FIFTH, or trifacial nerve, appears just behind the fourth, 
emerging from the side of the pons. It has its superficial, or 
apparent origin, by two roots which spring from the lateral 
aspect of the pons, the anterior, consisting of two or three bun- 
dles, being the motor and the posterior the sensory, root. The 
deep origin is from the floor of the fourth ventricle. 
The two roots pass through the dura just above the internal 
auditory meatus and continue forward to cross the apex of 
the petrous portion of the temporal bone, where a gangliform 
enlargement, called the Gasserian ganglion, is formed on the 
posterior or sensory root. The motor root passes beneath the 
ganglion of Gasser without being connected with it. 
The ganglion divides into three branches, ophthalmic, szcperior 
maxillary, and inferior maxillary. The last is joined bodily by 
the small root of the nerve and is, therefore, the only one of the 
three divisions possessing motor endowments. Besides its ter- 
minal branches the ganglion gives off branches to the dura and 
middle fossa of the skull and receives a communication from 
the cavernous plexus. 
Ophthalmic Nerve. 
The OPHTHALMIC branch passes forward and soon divides 
into three branches, lachrymal, frontal and nasal, which enter 
the orbit through the foramen lacerum anterius. This nerve 
passes through an opening in the dura lying below and external THE CRANIAL NERVES. 
503 
to that for the fourth. It then runs forward on the outer wall 
of the cavernous sinus, its place being below and to the outer 
side of the third and fourth. The terminal branches are given 
off just before the nerve reaches the sphenoidal fissure. 
Branches. 
Lachrymal. 
Frontal. 
Nasal. 
Lachrymal. 
The lachrymal branch of the ophthalmic passes through 
the upper, external portion of the sphenoidal fissure and enters 
the orbit where it runs along the external wall lying above the 
external rectus muscle. It continues its course until it reaches 
the lachrymal gland, which it supplies, and then sends filaments 
which pierce the palpebral ligament and are distributed to the 
skin of the upper eyelid and communicate with the facial nerve. 
Frontal. 
The FRONTAL is the largest branch of the ophthalmic division. 
It enters the orbit through the sphenoidal fissure, lying between 
the lachrymal, externally, and the fourth, internally. It then 
runs forward on the levator palpebrse and divides into the 
supra-trochlear and supraorbital. 
The supraorbital emerges from the orbit through the supra- 
orbital foramen, gives off branches to the upper eyelid and 
the muscles and integument of the head as far back as the 
vertex. While lying in the orbicularis palpebrarum, it com- 
municates with the facial nerve. 
The supra-trochlear branch advances to the inner angle of the 
orbit where it emerges above the fovea trochlearis, hence its 
name, and is distributed to the inner angle of the eye and the 
integument of the root of the nose and middle of the forehead. 
It gives a communicating branch to the infra-trochlear branch 
of the nasal. 504 
DESCRIPTIVE ANATOMY. 
Nasal. 
The nasal nerve enters the orbit between the heads of the ex- 
ternal rectus, lies beneath the superior oblique and the levator 
palpebrae, crosses the optic nerve, advances along the inner wall 
of the orbit, re-enters the cranium through the anterior eth- 
moidal foramen, and is there found lying in the slit beside the 
crista galli, whence it sinks into the cavity of the nose and di- 
vides into a branch for the mucous membrane of the nose, and 
another to descend along the posterior aspect of the nasal bone 
to its lower edge, where it emerges through the notch found 
there and supplies the integument of the nose to its tip. Just 
as the nasal nerve is entering the ethmoidal foramen it gives off 
a branch called the infra-trochlear, which passes forward to 
emerge at the inner angle of the orbit below the fovea troch- 
learis and supplies the lachrymal sac and inner angle of the eye, 
communicating with a similar branch from the supra-trochlear. 
Besides the infra-trochlear it gives off in the orbit three other 
branches; one to the ophthalmic ganglion of the sympathetic 
system and two ciliary branches which pierce the sclerotic coat, 
pass forward between it and the choroid and are distributed to 
the iris. 
Superior Maxillary Nerve. 
The superior MAXILLARY (n. maxillaris) division of the fifth 
nerve, like the ophthalmic, has a forward course. It gains egress 
through the foramen rotundum, continues its forward direction 
across the spheno-maxillary fossa, then along the groove on the 
floor of the orbit, sinks beneath the floor and emerges at the 
infra-orbital foramen on the face to give sensibility to adjacent 
parts, viz: the lower lid, cheek, side of the nose and upper lip. 
Branches. 
Besides the terminal ones, the branches of the superior max- 
illary are the following, emitted in the order given: THE CRANIAL NERVES. 
505 
Meningeal to accompany the middle meningeal artery and sup- 
ply the dura. 
The orbital, or tempor o-malar, branch enters the orbit through 
the spheno-maxillary fissure and divides into two branches, tem- 
poral and malar. The temporal branch enters the temporal fossa 
through the outer wall of the orbit, while the malar branch con- 
tinues along the outer wall of the orbit to emerge on the cheek 
at the outer angle. 
The spheno-palatine are two branches of communication which 
descend to Meckel's ganglion of the sympathetic in the spheno- 
maxillary fossa. 
The chief distribution of the superior maxillary is to the teeth 
and gums of the upper jaw and this is effected by three branches, 
anterior, middle, and posterior dental. The posterior dental is 
first emitted and supplies the molar teeth. It is given off before 
the nerve enters the infra-orbital canal and, after supplying the 
teeth and gums, communicates with the middle dental. The 
middle dental is given off just after the nerve enters the infra- 
orbital canal. It passes downward near the anterior and, after 
supplying the bicuspid teeth, communicates with the posterior 
and anterior dental nerves. 
The anterior dental leaves the main trunk just as it is about 
to emerge on the face and supplies the two incisors and the ca- 
nine. The anterior and posterior dental nerves communicate 
in the bone and supply each tooth with as many filaments as the 
tooth has fangs, besides giving twigs to the gums. 
The terminal branches are palpebral, which pass beneath the 
orbicularis palpebrarum to supply the integument and conjunc- 
tiva of the lower eyelid; the nasal passing inward to the side 
of the nose to supply it and join the nasal branch of the ophthal- 
mic division; and the labial distributed to skin of the upper lip, 
the mucous membrane and labial glands. These branches all 
join the facial and form the infra-orbital plexus. 
Inferior Maxillary Nerve. 
The inferior maxillary (n. mandibularis) division of the 
fifth nerve consists of a branch from the ganglion of Gasser and 506 
DESCRIPTIVE ANATOMY. 
the small motor root of the fifth nerve, which unite and pass 
downward through the foramen ovale, immediately after emerg- 
ing from which the nerve divides into an anterior and a poste- 
rior trunk. The distribution of each trunk is as follows: 
The anterior trunk breaks up into branches which supply the 
muscles of mastication, each branch bearing the name of the 
muscle to which it is distributed and conveying motor impulses. 
The masseteric branch runs out above the external pterygoid 
muscle, crosses through the sigmoid notch and is distributed to 
the deep face of the masseter. 
The deep temporal branches, anterior and posterior, are 
distributed to the deep face of the temporal muscle. 
The buccal branch passes between the two heads of the ex- 
ternal pterygoid, sometimes lying beneath the coronoid process 
and sometimes running through the temporal muscle, to be dis- 
tributed by an upper and a lower branch to the buccinator. 
The pterygoid branches are one to each pterygoid muscle; 
that to the external pterygoid being frequently a branch of the 
buccal nerve. 
The recurrent branch passes back through the foramen 
spinosum to accompany the middle meningeal artery and supply 
the dura mater. 
The posterior trunk divides into three branches, inferior den- 
tal, gustatory, and auriculo-temporal. 
Inferior Dental. 
The inferior dental branch curves forward and downward, 
accompanied by the inferior dental artery, to enter the dental 
foramen of the lower jaw and run along a canal in the bone 
giving filaments to all the teeth of the lower jaw. It first lies 
beneath the external pterygoid muscle and then between the 
internal lateral ligament and the ramus of the lower jaw. 
As it passes the mental foramen it gives off a branch which 
escapes through that foramen and supplies the integument of 
the lower lip. Just before entering the dental foramen the nerve 
gives off a branch called the mylo-hyoidean, which descends 
along the groove on the inner surface of the inferior maxilla THE CRANIAL NERVES. 
507 
and is distributed to the mylo-hyoid muscle and the anterior 
belly of the digastric. 
Gustatory Branch. 
The gustatory, or lingual nerve passes downward and for- 
ward, first behind the external pterygoid muscle, with the in- 
ferior dental lying to its side, then between the two pterygoid 
muscles and then between the internal pterygoid and ramus of 
the lower jaw, and reaching the side of the tongue, splits into 
many filaments to supply the anterior part of that organ. While 
between the two pterygoid muscles it receives at an acute angle, 
the chorda tympani, a branch of the seventh nerve, which it 
transmits to the sub-maxillary ganglion of the sympathetic. 
Beneath the tongue the gustatory gives off a branch of com- 
munication to the twelfth. 
It distributes branches to the filiform and fungiform papillae, 
the mucous membrane of the tongue, mouth, and gums. It 
communicates with the seventh, through the chorda tympani, 
the hypoglossal, and the sub-maxillary ganglion. 
Auriculo-Temporal. 
The auriculo-temporal branch arises by two roots, between 
which the middle meningeal may lie. It first passes backward 
behind the articulation of the lower jaw, then ascends between 
the meatus auditorius externus and condyle of the lower jaw, 
and emerging from beneath the parotid gland, divides into 
branches called anterior and posterior temporal, which supply 
the integument of the temporal region. It gives off branches 
to the articulation of the lower jaw, to the parotid gland, to 
the pinna, to the meatus auditorius and two communicating 
branches to the facial nerve. 
Sixth Nerve. 
The sixth nerve, or ABDUCENS, has its apparent origin from 
the upper constricted portion of the medulla, just behind the 508 
DESCRIPTIVE ANATOMY. 
pons, while its deep origin can be traced to a mass of gray mat- 
ter lying in the floor of the fourth ventricle. The nerve, after 
piercing the dura just below the posterior clinoid process, passes 
forward in the cavernous sinus, lying internal to the preceding 
nerve and in close contact with the internal carotid artery. 
Continuing its course it passes into the orbit through the 
sphenoidal fissure just external to the ophthalmic vein, runs be- 
tween the two heads of the external rectus and is distributed 
to that muscle from its deep surface. While in the cavernous 
sinus the sixth nerve is internal to all the others, close to the 
carotid artery; while the third, the fourth, and the ophthalmic 
division of the fifth lie on the outer wall in numerical order 
from above downward and from within outward. In the sphe- 
noidal fissure the fourth, frontal, and lachrymal lie on the upper 
wall from within outward; while the sixth inferior division of 
the third, nasal, and superior division of the third run from 
within outward on the lower wall. (Gray.) 
Seventh Nerve. 
The seventh, or facial, nerve (the motor nerve of the face) 
is the uppermost of the five nerves which spring from the groove 
between the corpora olivare and restiforme. Its deep origin is 
from the floor of the fourth ventricle, where it communicates 
with the sixth nerve. Just beneath it, in the same groove, is 
another nerve called the portio intermedia which unites with 
it. If this be counted as a separate nerve, it may be said that 
there are six nerves springing successively from this groove. 
It makes for the internal auditory meatus which it enters in 
company with the auditory nerve; and, when the two reach the 
bottom of the canal, the facial parts from its companion and 
enters another canal in the petrous bone called the aqueduct 
of Fallopius, which conducts it first outward, then backward 
and then downward to the stylo-mastoid foramen, emerging 
from which it passes forward through the parotid gland, over 
the external carotid artery, and divides into numerous branches 
which are distributed to all the muscles of the face except those 
of mastication, and of these the buccinator gets a branch. THE CRANIAL NERVES. 
509 
Branches. 
Like other cranial nerves, its branches may be divided into 
two sets, viz.: communicating and branches of distribution. 
While in the auditory meatus, it communicates with the auditory 
nerve. In the aqueductus Fallopii the large superficial petrosal 
is sent to Meckel's ganglion, the small superficial petrosal to the 
optic ganglion and the external petrosal to the sympathetic on 
the middle meningeal artery. After the nerve emerges from 
the stylo-mastoid foramen, communications are established with 
the ninth and tenth cranial nerves, with the carotid plexus, 
with the auricularis magnus of the cervical plexus and with the 
auriculo-temporal branch of the fifth. All of the divisions of 
the fifth communicate with the seventh on the face. 
Of the branches of distribution the tympanic and chorda 
tympani arise within the aqueductus Fallopii; the posterior 
auricular, stylo-hyoid and digastric arise outside the stylo-hyoid 
foramen, and two terminal branches, the temporo-facial and 
cervico-facial spring from the nerve after it crosses the carotid. 
The tympanic, which arises from the facial while it is in the 
aqueduct of Fallopius, is distributed to a muscle of the tympanic 
cavity. 
The chorda tympani, which is emitted from the facial just 
above the stylo-mastoid foramen, first ascends through the 
petrous bone and enters the tympanum at the base of the pyra- 
mid on its posterior wall, then crosses on the inner surface of 
the membrana tympani and leaves through the fissure of Glaser, 
having emerged from which it joins the gustatory nerve between 
the two pterygoid muscles and continues with it to the sub- 
maxillary ganglion. 
The stylo-hyoid supplies the stylo-hyoid muscle. 
The digastric is distributed to the posterior belly of the 
digastric muscle. 
The posterior auricular ascends behind the ear, and after 
communicating with the auricular branch of the pneumogastric 
is distributed by an anterior branch to the auricle and by a pos- 
terior to the back of the head. 510 
DESCRIPTIVE ANATOMY. 
The temporo-facial is the larger of the two terminal branches 
of the seventh. It passes through the parotid gland, which 
separates it from the external carotid artery, and breaks up into 
three sets of branches-temporal, malar, and infra-orbital, the 
first supplying the attrahens aurem, occipito-frontalis, and or- 
bicularis palpebrarum muscles; the second the orbicularis, and 
corrugator supercillii, while the last, the largest branch, supplies 
the pyramidalis nasi, levator labii superioris and levator an- 
guli oris. 
The cervico-facial division passes downward in the substance 
of the parotid gland, which separates it from the external 
carotid. It communicates with the auricularis magnus and di- 
vides into buccal branches, which supply the buccinator and 
orbicularis oris; supra-maxillary for the depressor anguli oris; 
and infra-maxillary, some of which supply the platysma while 
others pass to the skin over the supra-hyoid region, communi- 
cating with the branches of the cervical plexus in that region. 
Eighth Nerve. 
The eighth nerve, or portio mollis, or auditory, is the sec- 
ond of the nerves arising from the groove between the corpora 
olivare and restiforme, its deep origin being from the floor of 
the fourth ventricle. It passes forward and enters, along with 
the seventh, the internal auditory meatus, at the bottom of 
which it divides into a cochlear and three vestibular branches, 
which are distributed to corresponding parts of the labyrinth. 
Ninth Nerve. 
The ninth nerve, or GLOSSO-PHARYNGEAL, is the third nerve 
arising in the groove between the corpora olivare and restiforme. 
Its deep origin is from the floor of the fourth ventricle between 
the eighth and tenth. It escapes from the cranium, along with 
the tenth and eleventh, through the posterior lacerated fora- 
men, lying behind the internal carotid artery; it then passes 
forward between the artery and the internal jugular vein to 
the outer side of the artery, then crosses the artery in front THE CRANIAL NERVES. 
511 
of the posterior border of the stylo-pharyngeus, and then crosses 
that muscle to be distributed by its terminal filaments to the 
mucous membrane of the posterior part of the tongue. 
This nerve presents two gangliform enlargements called 
superior, or jugular, and inferior, or petrous. The superior, 
which is very small, is situated in the jugular foramen and 
does not involve all the fibres of the nerve. The inferior ganglion 
is situated in a depression on the posterior border of the petrous 
portion of the temporal bone and gives off branches of com- 
munication to the facial, pneumogastric, and sympathetic. 
Branches. 
Besides its terminal branches the ninth nerve gives off four 
branches of distribution. 
The tympanic branch, Jacobson's nerve, passes to the tympa- 
num through a canal which opens on the ridge of bone between 
the carotid and jugular foramina. After reaching the tympa- 
num it is distributed by six branches, as follows: 
(a) One to the lining membrane of the tympanum and Eu- 
stachian tube. 
(b) One to the fenestra rotunda. 
(c) One to the fenestra ovalis. 
(d) One to the carotid plexus of the sympathetic. 
(e) One to the great superficial petrosal nerve. 
(/) One to the lesser superficial petrosal nerve. 
A muscular branch which supplies the stylo-pharyngeus. 
The pharyngeal branches, which are found on the posterior 
part of the pharynx aiding to form a plexus called the pharyn- 
geal from which the pharynx is supplied. The other nerves 
entering into the formation of this plexus are the pharyngeal 
and superior laryngeal of the tenth and the sympathetic. 
The tonsillar branches which form a plexus on the tonsils. 
The branches of communication of the ninth nerve are as 
follows: 
One to the ganglion of the tenth nerve. 
One to the superior cervical ganglion of the sympathetic. 512 
DESCRIPTIVE ANATOMY. 
One to the seventh nerve. 
Carotid filaments which descend with the carotid artery. 
Tenth Nerve. 
The tenth nerve, or pneumogastric, or par vagum, is the 
fourth nerve arising from the groove between the corpora 
olivare and restiforme. It escapes from the cranium through 
the jugular foramen and, descending the neck, enters the thorax 
through which it passes along with the oesophagus and gains the 
abdomen where it is found running from the left to right along 
the lesser curvature of the stomach. In the neck the course and 
relations of the nerve are the same on both sides, i. e., the 
nerve lies first between the internal jugular vein and the in- 
ternal carotid artery, then between the internal jugular vein 
and common carotid artery until it reaches the root of the neck 
and the relations thenceforward vary according to the side. 
The right nerve at the root of the neck crosses the first por- 
tion of the subclavian artery, enters the chest, reaches the pos- 
terior aspect of the root of the right lung; descends thence along 
the posterior aspect of the oesophagus to the stomach and runs 
along the lesser curvature of that organ, being distributed by 
its terminal filaments to its posterior face. 
The left enters the thorax lying on the front of the first por- 
tion of the left subclavian, crosses the front of the arch of the 
aorta, reaches the posterior aspect of the root of the left lung 
and thence passes down the front of the oesophagus to the 
stomach, runs along its lesser curvature, and is distributed to 
its anterior face. While in the jugular foramen the nerve pre- 
sents a gangliform enlargement called the ganglion of the root, 
and about half an inch below this a second and larger one called 
the ganglion of the trunk. 
Branches. 
The branches are divided into communicating and branches 
of distribution. The communicating are mainly connected with 
the two ganglia on the nerve. The ganglion of the root receives THE CRANIAL NERVES. 
513 
branches from the accessory portion of the spinal accessory, 
the petrous ganglion of the ninth, the facial, and from the 
superior cervical of the sympathetic. 
The ganglion of the trunk is connected with the twelfth, the 
superior cervical ganglion of the sympathetic, and with the 
loop between the first and second cervical. 
The branches of distribution are: 
Auricular. 
Pharyngeal. 
Thoracic Cardiac. 
Anterior Pulmonary. 
Superior Laryngeal- 
Posterior Pulmonary. 
Recurrent Laryngeal. 
(Esophageal. 
Cervical Cardiac. 
Gastric. 
Of these branches the first arises in the jugular fossa, the 
next four in the neck and the remainder, except the gastric, 
which comes off in the abdomen, in the thorax. 
The auricidar, or Arnold's nerve, is a small branch which 
springs from the ganglion of the root. Passing through a small 
canal in the jugular fossa it runs through the petrous portion 
of the temporal, where it communicates with the facial, leaves 
the temporal through the auricular fissure, and is distributed 
to the back of the pinna, communicating with the auricularis 
magnus. 
The pharyngeal branch arises from the ganglion of the root 
and descends to the posterior aspect of the pharynx to aid in 
forming the pharyngeal plexus. It passes across the internal 
carotid, usually behind, to the upper edge of the middle con- 
strictor, where it breaks up into branches. It receives its motor 
fibres probably from the eleventh and communicates with the 
ninth, superior laryngeal and the sympathetic to form the 
pharyngeal plexus. 
The superior laryngeal branch arises from the ganglion of 
the trunk and descending pierces the thyro-hyoid membrane and 
is distributed to the mucous membrane of the laryx, giving a 
filament to the arytenoid muscle. Just below the thyro-hyoid 
membrane it gives off a branch called the external laryngeal, 
which is distributed to the thyroid gland and crico-thyroid 514 
DESCRIPTIVE ANATOMY. 
muscle and furnishes some filaments to the pharyngeal plexus. 
This nerve receives a communication from the eleventh and 
afterward communicates with the recurrent laryngeal and with 
the pharyngeal plexus. In its course down the neck it lies by 
the side of the pharynx and crosses behind the internal carotid 
artery. 
The recurrent or inferior laryngeal branch arises at a differ- 
ent point on each side; on the left it arises as the pneumogastric 
is crossing the aorta and winds backward around the aorta; 
on the right it arises as the nerve is crossing the first por- 
tion of the subclavian and winds around that artery. After 
passing around the aorta (or subclavian, as the case may be) 
each nerve ascends in the groove between the trachea and oeso- 
phagus, giving filaments to those parts, and is distributed to all 
the intrinsic muscles of the larynx except the crico-thyroid. 
Each nerve gives off cardiac branches which unite with those 
from the sympathetic and tenth to form the cardiac plexuses. 
There are more oesophageal branches given off from the right 
than from the left nerve. Other branches supply the mucous 
membrane of the trachea and some branches pass to the in- 
ferior constrictor. 
The cervical cardiac branches are divided into superior and 
inferior. The s.uperior usually joins the great cardiac plexus, 
as does the inferior on the right. The left inferior goes gen- 
erally to the superficial plexus. 
The thoracic cardiac branches of the right side come directly 
from the right nerve, but all the left thoracic come from the 
left recurrent laryngeal. They all pass to the deep plexus. 
The posterior pulmonary branches form an intricate plexus 
on the back of the root of the lung, whence filaments are sent 
along the bronchial tubes into the lungs. 
The anterior pulmonary branches form a smaller plexus on 
the front of the root of the lung. 
The oesophageal branches are filaments furnished the oeso- 
phagus before the nerves are in relation with it. 
The two nerves communicate frequently around the tube, thus 
forming the oesophageal plexus. THE CRANIAL NERVES. 
515 
The gastric, or terminal, branches are distributed to both 
faces of the stomach, the right nerve going to the back, and the 
left to the front, of that organ. The two communicate with each 
other and with the coeliac, splenic, and hepatic plexuses. 
Eleventh Nerve. 
The eleventh nerve, or spinal accessory, is the fifth nerve 
arising in the groove between the corpora olivare and resti- 
forme and escapes from the cranium through the posterior fora- 
men lacerum along with the ninth and tenth nerves. The nerve 
consists of two portions: 1st, a cranial or accessory portion 
which arises from the groove mentioned and, after communicat- 
ing with the spinal portion, goes to the pneumogastric; 2d, a 
spinal portion which arises by successive filaments from the 
side of the spinal cord as low as the sixth cervical nerve and 
ascends between the two roots of the spinal nerves. It enters 
the cranium through the foramen magnum and, after communi- 
cating with the accessory portion, emerges through the jugular 
foramen, passes downward and outward, pierces the sterno- 
cleido-mastoid muscle and reaches the trapezius, to which it is 
distributed, giving, on its way, filaments to the sterno-cleido- 
mastoid. The two portions of this nerve are never closely 
united, but after the spinal portion has ascended to the cranium 
several communicating branches pass between them. 
Twelfth Nerve. 
The twelfth nerve, arises from the groove between the cor- 
pus olivare and the pyramid by ten or twelve filaments which 
are gathered into two bundles. Its deep origin is from the 
trigonum hypoglossi on the floor of the fourth ventricle. The 
two bundles pass outward and, just as they are leaving the 
cranium through the anterior condyloid foramen, unite to form 
the trunk of the nerve. The nerve then descends between the 
internal jugular vein and internal carotid artery and, when it 
reaches a point on a level with the jaw, curves forward in front 
of both internal and external carotid arteries, and after com- 516 
DESCRIPTIVE ANATOMY. 
municating with the gustatory nerve is distributed to the mus- 
cles of the tongue. 
Branches. 
The branches of distribution, besides the terminal, are two, 
the descendens noni, a very important branch, and the thyro- 
hyoidean of small importance. 
The descendens noni leaves the hypoglossal just as it is cross- 
ing the external carotid artery and derives its name from its 
direction and from the fact that the twelfth nerve was, in 
Willis' classification, called the ninth. It passes down the neck 
on the front of the sheath of the external carotid artery, and 
then on the sheath of the common carotid, occasionally descend- 
ing in the sheath. About the middle of the neck it is joined by 
filaments from the second and third cervical nerves, the com- 
municans noni, forming what is called the arch of Scarpa, 
which lies in front of the sheath of the common carotid artery 
about the middle of the neck. From this arch branches are 
given to the depressor muscles of the hyoid bone, except the 
thyro-hyoid. 
The thyro-hyoidean branch descends from near the termina- 
tion of the hypoglossal nerve to supply the thyro-hyoid muscle. 
Upon examining the lower surface of the skull it will be seen 
that the anterior condyloid foramen is somewhat internal to and 
behind the jugular foramen and the carotid aperture of en- 
trance. The relations of the 9th, 10th 11th and 12th nerves, at 
the base of the skull and low'er down, to the internal carotid and 
internal jugular are, therefore, of great importance. At the 
base of the skull the artery is the most anterior, the vein most 
external and the twelfth most internal of all these structures. 
As they pass downward the ninth continues between the vein 
and artery until it reaches the stylo-pharyngeus, where it 
crosses the artery and ceases to be a relation. The tenth, just 
behind the ninth, comes to the front and bears a postero-exter- 
nal relation to the artery and a postero-internal relation to the 
vein. The eleventh passes outward almost at once, and may 
be either behind or in front of the vein. The twelfth is at first THE SYMPATHETIC NERVES. 
517 
behind and internal to the artery, soon crosses behind it to get 
to the interval between vein and artery, runs down slightly in 
front of and between the two, until the lower border of the di- 
gastric is reached, when it crosses in front of the two carotids 
and ceases to be a relation. 
THE SYMPATHETIC NERVES. 
The sympathetic nervous system consists of a vertebral and a 
cranial portion. 
The vertebral portion of the sympathetic consists of two 
similar series of ganglia, lying one on each side of the vertebral 
column, extending from the skull to the coccyx, and the nerves 
which are connected with these ganglia. Of these ganglia there 
are about twenty-four, divided into cervical, of which there are 
three; dorsal, of which there are twelve; lumbar, of which there 
are four or five; and sacral, of which there are about four. Each 
ganglion is provided with four sets of branches: 1, ascending to 
connect it with the ganglion above; 2, descending to connect it 
with the ganglion below; 3, external to connect it with the con- 
tiguous spinal nerve; 4, internal or branches of distribution. 
The first three sets of branches are the communicating branches, 
and each of the connections, viz., with the ganglion above, the 
ganglion below, and the spinal nerves, is affected by two fila- 
ments, one of which is gray and the other white. The fourth 
set of branches, the internal, or distributing, pass, as a rule, 
inward and forward to supply the organs of their various re- 
gions; these branches going either singly to their destination, 
or, as in some cases, several branches from one side meet similar 
ones from the opposite side and communicating with them on the 
front of the vertebral column, form plexuses from which the 
branches of distribution proceed. Three of these plexuses exist, 
known as the cardiac, solar and hypogastric, these constituting 
what is called the prsevertebral sympathetic. As a rule each 
ganglion is connected with but one spinal nerve, but to this there 
are exceptions, which will be found in the cervical portion. 518 
DESCRIPTIVE ANATOMY. • 
Cervical Portion. 
The cervical portion of the sympathetic is that part of the 
chain or trunk which is found in the cervical region. Although 
there are eight cervical spinal nerves, there are only three sym- 
pathetic ganglia, known respectively as superior, middle, and 
inferior. 
The Superior Cervical Ganglion. 
The superior cervical ganglion lies on the front lateral 
aspect of the second and third cervical vertebrae, is fusiform in 
shape, varies in size, and is found to be segmented so as to cor- 
respond to the four upper cervical vertebrae. It receives com- 
munications, by means of its external branches, from the first, 
second, third, and fourth cervical nerves, and also smaller 
branches from the glosso-pharyngeal, pneumogastric, and hypo- 
glossal nerves. This ganglion being situated between the spinal 
and cranial nerves, receives communications from both sets. 
It lies directly behind the internal carotid artery; and the 
cord which connects it with the middle cervical ganglion passes 
downward behind the common carotid artery, resting upon the 
prevertebral group of muscles. 
Its ascending branches pass along the internal carotid artery 
and are divided into two sets of branches, one entering into the 
formation of the cavernous and the other into the carotid plexus. 
The descending branches, white and gray, connect it with the 
middle cervical ganglion. 
Its branches of distribution are three in number, viz., the 
pharyngeal, which unite with branches of the glosso-pharyn- 
geal and pneumogastric nerves, and with them form a plexus 
situated on the posterior wall of the pharynx, which divides into 
numerous minute twigs, distributed to the muscles, blood-ves- 
sels, and glands of that organ. The laryngeal branches unite 
with the superior laryngeal branch of the pneumogastric, and 
form a plexus distributed to the larynx. The last branch is 
given to the heart, and is called the superior cardiac, to distin- 
guish it from smaller branches derived from the middle and in- THE SYMPATHETIC NERVES. 
519 
ferior cervical ganglia. This is a long, slender nerve, which 
passes down the neck behind the common carotid artery, cross- 
ing on the right side, sometimes behind, sometimes in front of 
the first portion of the subclavian artery, while on the left side 
it passes behind the thoracic portion of the subclavian. The 
nerve then enters the thoracic cavity. On the right side it joins 
with the great deep cardiac plexus, while on the left side it 
unites with the great superficial cardiac plexus. 
The Middle Cervical Ganglion. 
The MIDDLE CERVICAL ganglion is situated opposite the fifth 
cervical vertebra, is very small in size, and frequently is ap- 
parently absent. 
Its superior branch communicates with the upper cervical 
ganglion, its inferior branch with the lower, while its external 
branches correspond to the fifth and sixth cervical nerves. 
Its internal branches, or branches of distribution, are the mid- 
dle cardiac and thyroid. 
The thyroid passes over the inferior thyroid artery just at the 
point at which it makes its bend to turn inward towards the 
thyroid gland; and communicating with the superior cardiac 
and a branch of the recurrent and external laryngeal nerves, is 
distributed to the thyroid body. 
The middle cardiac nerve, the largest of the three cardiac 
branches, arises either from the middle cervical ganglion or 
from the cord between that ganglion and the superior. It passes 
down the neck behind the common carotid artery, and at the 
root of the neck the right nerve passes sometimes in front and 
sometimes behind the subclavian artery, descends upon the tra- 
chea, and, after receiving filaments from the recurrent laryn- 
gea nerve, joins the great deep cardiac plexus. On the left side 
it enters the chest between the left common carotid and the sub- 
clavian arteries, and joins the deep cardiac plexus. 520 
DESCRIPTIVE ANATOMY. 
The Inferior Cervical Ganglion. 
The inferior cervical ganglion is situated between the bases 
of the transverse processes of the last cervical and the first dor- 
sal vertebrae. It is probably the product of the last two cervical 
nerves, the two ganglia having coalesced to form a single one. 
It is not infrequently blended with the first thoracic ganglion. 
Its ascending fibres communicate with the middle cervical, and 
its lower, or descending fibres, with the first dorsal ganglion, 
when that ganglion fails to coalesce with the last cervical. 
Its external fibres are derived from the last two cervical 
nerves, the seventh and eighth, while its internal branch is the 
last of the three cardiac nerves. In communicates with the re- 
current larngeal and middle cardiac nerve; and then passing 
into the thoracic cavity, unites with the deep cardiac plexus. 
The Cardiac Nerves. 
It will be seen that there are two large plexuses connected 
with the heart and supplying the muscular fibres of that organ. 
These are known as the great deep cardiac plexus and the su- 
perficial cardiac plexus. 
The superficial plexus is found lying on the ductus arteriosus, 
and is the product of the superior cardiac nerve of the left side 
and the inferior cervical cardiac branch of the left pneumo- 
gastric. 
The deep plexus, situated in the bifurcation of the trachea, is 
formed by the three cardiac nerves of the right side and the 
middle and the inferior cardiac nerves of the left side. 
Thus it is seen that only two cardiac nerves enter the super- 
ficial plexus, viz., the left superior cardiac from the sympathetic, 
and the inferior cervical cardiac branch from the left pneumo- 
gastric; while the deep cardiac plexus is formed by the three 
right cardiac branches from the sympathetic, the left, middle, 
and lower sympathetic, and the superior cervical and thoracic 
cardiac branches of the right pneumogastric. 
From these two plexuses branches proceed, which following 
the course of the coronary arteries, are distributed along these THE SYMPATHETIC NERVES. 
521 
vessels to the muscular coats of the vessels themselves and to 
the fibres of the heart. 
The Thoracic Portion of the Sympathetic. 
The thoracic, or dorsal, sympathetic consists of twelve gan- 
glia on either side of the body, corresponding to the number and 
position of the dorsal vertebrae. These ganglia are uniformly 
arranged, and consist, like other sympathetic ganglia, of as- 
cending branches communicating with the ganglion above, de- 
scending branches communicating with the ganglion below, ex- 
ternal, which are usually two branches, and communicate with 
the corresponding dorsal nerves, and internal, which are 
branches of distribution. 
The branches of distribution, coming from the dorsal sympa- 
thetic, are almost entirely confined to the abdominal cavity. 
They form three nerves, known as the greater, lesser, and least 
splanchnic. 
The internal branches of the ganglia are divided into two 
sets: the upper and small ones are distributed along the branches 
of the thoracic aorta; while of the lower ones, those between 
the sixth and tenth ganglia unite to form the great splanchnic 
nerve, the tenth and eleventh ganglia form the lesser splanchnic, 
and the least, or renal splanchnic is the product of the twelfth. 
The great splanchnic nerve passes down the front of the 
vertebral column behind the peritoneum, pierces the correspond- 
ing crus of the diaphragm, and enters into the semi-lunar 
ganglion of its side. 
The lesser splanchnic nerve, the product of the tenth and 
eleventh ganglia, also pierces the crus of the diaphragm, and 
joins with the coeliac plexus; while the smallest, or least 
splanchnic terminates in the renal plexus. 
The semi-lunar ganglia, found on either side of the coeliac 
axis, are apparently enlargements of the greater splanchnic 
nerve. Each ganglion gives off branches which communicate 
with the ganglion of the opposite side, forming a complete net- 
work surrounding the lateral and anterior aspects of the ab- 
dominal aorta, and completely enveloping the coeliac axis. These 522 
DESCRIPTIVE ANATOMY. 
numerous branches are collectively known as the solar plexus 
of nerves. 
From this solar plexus large branches follow the three ar- 
teries, into which the coeliac axis divides; and, forming plexuses 
along the the course of these vessels, known as the gastric, 
hepatic, and splenic plexuses, are distributed to the organs which 
these vessels supply, and to the coats of the vessels themselves. 
The lesser splanchnic, after piercing the diaphragm, enters 
into the coeliac plexus; and some of its branches accompany the 
ramifications of the arteries mentioned above, while other fila- 
ments descend to the renal plexus, where that communicates 
with the least splanchnic nerve. 
The least splanchnic, after piercing the diaphragm, enters 
into the formation of the renal plexus, from which branches 
pass to the kidney and to the renal artery and vein. 
In addition to the filaments accompanying the branches of 
the coeliac axis, the solar plexus also gives off branches which 
accompany the phrenic, superior mesenteric, spermatic (or 
ovarian in the female), and inferior mesenteric branches of the 
abdominal aorta; and are distributed along with these numerous 
branches. In addition to these certain fibres also accompany 
the aorta to form the aortic plexus of nerves, which, after 
communicating with the inferior mesenteric plexus, passes over 
the pelvic brim, and aids in forming a plexus on the front of 
the sacrum, which is called the hypogastric. From this branches 
proceed, which are united over the coccyx to form the ganglion 
impar, or terminal ganglion of the sympathetic system. 
The Lumbar Portion of the Sympathetic. 
The lumbar portion of the sympathetic system is continuous 
above with the dorsal by means of the branch which passes 
from the last dorsal sympathetic ganglion beneath the liga- 
mentum arcuatum to the first lumbar. The lumbar ganglia 
vary in number, being from three to five. 
They receive their branches of communication from the lum- 
bar spinal nerves, a descending branch of communication from 
the ganglion above, and give a communicating branch to the THE SYMPATHETIC NERVES. 
523 
ganglion below. These ganglia lie along the inner side of the 
psoas magnus muscle, where they receive communicating 
branches of the lumbar nerves. 
Of the internal branches of this plexus there are two sets. 
The upper set passes to the front of the abdominal aorta, and 
forms there the aortic plexus, which receives branches of com- 
munication from the solar plexus and from the semi-lunar 
ganglion. 
This plexus lies between the origin of the superior and the 
inferior mesenteric arteries, and gives off branches to the in- 
ferior mesenteric and the spermatic arteries and to the inferior 
vena cava. 
The lower internal branches enter into the formation of the 
hypogastric plexus, which is situated on the promontory of the 
sacrum between the common iliac vessels, and from which 
branches are given off to supply the pelvic viscera, communi- 
cating with ganglia which correspond to the sacral nerves. 
Smaller branches are often given off from the sacral nerves 
which unite to form the so-called pelvic plexus. This plexus, 
after distributing branches to the lower pelvic viscera, cor- 
responding to the arteries which pass to them, the branches 
being the inferior hemorrhoidal, vesical, and prostatic in the 
male, and vaginal and uterine in the female, finally terminates 
by uniting over the mid-line of the body to form the ganglion 
impar, or termination of the sacral plexus of sympathetic nerves. 
The Cranial Sympathetic. 
The CRANIAL PORTION of the sympathetic consists of four 
ganglia, lying in and around the skull, with their branches of 
communication and distribution, and of the carotid and caver- 
nous plexuses, formed by the ascending branches of the superior 
cervical ganglion. Each cranial ganglion is connected with two 
cranial nerves or two branches of the same nerve, receiving 
from one a motor and from the other a sensitive branch, and 
is also connected with the rest of the sympathetic system by a 
communicating branch. These various communicating branches 
form the roots of the ganglion. The four cranial ganglia are 524 
DESCRIPTIVE ANATOMY. 
the ophthalmic, the spheno-palatine, the otic, and the sub- 
maxillary. 
Ophthalmic Ganglion, or Ciliary Ganglion. 
The OPHTHALMIC, or LENTICULAR, GANGLION is found in the 
orbit lying on the outer side of the optic nerve close to the 
optic foramen, with the external rectus on its outer side and 
itself lying on the ophthalmic artery. It is small and reddish 
gray in color and receives three roots, or branches of com- 
munication. 
Its sensitive root is furnished by the nasal nerve; its motor 
root by the branch of the third nerve sent to the inferior oblique 
muscle; its sympathetic root by the cavernous plexus. The sym- 
pathetic root is frequently blended with the long or sensory 
root. 
Its branches of distribution, known as ciliary, five or six in 
number, pierce the sclerotic coat around the optic nerve, and 
ramifying between the tunics of the eyeball, terminate in 
the iris. 
Spheno-Palatine Ganglion. 
The SPHENO-PALATINE, or meckel's ganglion, is the largest 
of the cranial ganglia and is found lying in the spheno-maxillary 
fossa just beneath the superior maxillary division of the fifth 
nerve, and close to the spheno-palatine foramen. 
Its sensitive root consists of two filaments from the superior 
maxillary nerve; its motor root is derived from the facial nerve 
through the Vidian; its sympathetic root is derived from the 
carotid plexus through the Vidian. The last two roots reach 
the ganglion together, i. e., they are in the same sheath and 
form apparently one nerve; but the motor root, coming from 
the Vidian, separates from the other branch of that nerve at 
the termination of the Vidian canal, the other branch, the great 
superficial petrosal nerve, going to the facial through the hiatus 
Fallopii. The branches of distribution of this ganglion are 
four, palatine pharyngeal, superior nasal, and naso-palatine. THE SYMPATHETIC NERVES. 
525 
The three palatine branches, anterior, middle and posterior, 
descend to supply the roof of the mouth, soft palate and tonsils. 
The anterior palatine passes downward through the posterior 
palatine canal, emerges upon the hard palate and runs forward 
and inward to the anterior palatine foramen, communicating 
with the naso-palatine nerve. In the posterior palatine canal 
a branch is given off to the nose, the inferior nasal, which 
supplies the mucous membrane of the middle meatus and middle 
and inferior turbinated bones. Just as it emerges from the 
canal it gives off branches to the soft palate. 
The middle palatine, often absent, gives branches to the 
tonsils, uvula, and soft palate. 
The posterior palatine passes through an accessory palatine 
canal to supply the levator palati and azygos uvulae. 
The superior nasal are four or five branches which enter the 
nose through the spheno-palatine foramen and are distributed 
to the superior meatus of the nose. 
The naso-palatine enters the nose through the spheno-palatine 
foramen, runs inward to the septum and, after giving branches 
to it, enters the palate through the naso-palatine canal. 
The pharyngeal branches, or pterygoid-palatine, pass through 
the pterygo-palatine canal to reach the pharynx where it is 
distributed. 
The Vidian, one of the communicating branches, can be traced 
back through the Vidian canal to the middle lacerated foramen 
where it divides into the large superficial petrosal, which enters 
the cranium through the middle lacerated foramen, passes 
through the hiatus and aqueductus Fallopii to be connected with 
the gangliform enlargement of the facial; and the deep petrosal, 
which enters the carotid canal to join the plexus on the carotid 
artery. 
Otic Ganglion. 
The otic, or Arnold's ganglion, small and oval-shaped, is 
situated on the inner side of the inferior maxillary branch of 
the fifth nerve, just after its exit through the foramen ovale. 
Its sensitive root comes from the auriculo-temporal branch of 
the inferior maxillary; its motor root from the nerve to the DESCRIPTIVE ANATOMY. 
526 
internal pterygoid; its sympathetic root from the plexus on the 
middle meningeal artery. Its branches of distribution are three, 
as follows: 
A branch which passes backward to the tensor tympani muscle. 
A branch which passes forward to the tensor palati muscle. 
The nervus petrous superficialis minor, which first enters the 
cranium through a canal between the foramen ovale and fora- 
men spinosum and passing backward enters the tympanum, to 
join the tympanic plexus, through a canal on the base of the 
petrous bone. It gives off a branch (nerve of Longet) which 
enters the hiatus Fallopii to join the intumescentia gangliformis 
of the facial nerve. 
The Submaxillary Ganglion. 
The submaxillary ganglion is a minute speck situated near 
the posterior border of the mylo-hyoid muscle. It receives fila- 
ments from the gustatory, from the facial through the chorda 
tympani, and from the sympathetic on the facial artery. 
The branches of distribution are distributed to Wharton's 
duct, the mucous membrane of the mouth and a few to the sub- 
maxillary gland. 
THE OUTLET OF THE PELVIS. 
The outlet of the pelvis, which in the recent subject, is 
closed by various soft parts, in the skeleton is seen to be 
surrounded by the following parts: in front it is limited by the 
pubic arch, behind by the tip of the coccyx, on each side, about 
the centre, by the tuberosity of the ischium and running for- 
ward from this the rami of the ischium and pubis, and back- 
ward from it the greater sacro-sciatic ligament or, in the recent 
subject, the lower border of the gluteus maximus muscle. In 
the recent subject the outlet of the pelvis is divided into tw'o 
portions by a transverse line passing between the anterior edges 
of the two tuberosities of the ischia, or, in other words, from 
the indefinite point on one side where the ramus and tuberosity 
of the ischium meet to a similar point on the opposite side. THE OUTLET OF THE PELVIS. 
527 
The portion lying in front of this line is called the perineum, 
and that lying behind it the ischio-rectal region. 
Ischio-Rectal Region. 
The ischio-rectal region is bounded in front by the trans- 
verse line, behind by the apex of the coccyx, laterally by the 
great sacro-sciatic ligament or the lower edge of the gluteus 
maximus muscle and the tuberosity of the ischium. It contains 
three parts to be examined, the anal orifice with its sphincter 
muscle and, on each side of this, a subdivision known as the 
ischio-rectal fossa. 
Anus. 
The ANUS is the termination of the rectum, and is kept habitu- 
ally closed by the contraction of muscles called sphincters, in- 
ternal and external. The sphincter ani internus was described 
with the structure of the rectum, it being a muscular ring 
around the gut formed by an aggregation of its circular muscu- 
lar fibres about an inch above the anal orifice. Surrounding the 
anal orifice, which is seen in the centre of the ischio-rectal 
region, is a thin elliptical muscle called the sphincter ani ex- 
ternus. It arises from and around the tip of the coccyx and 
passes forward just beneath and closely adherent to the skin to 
surround the anal orifice, and be inserted in front of it into a 
point in the centre of the perineal line called the central point 
of the perineum. 
Ischio-Rectal Fossa. 
The ISCHIO-RECTAL FOSSA is the triangular, or wedge-shaped, 
space lying beside the anus, one on each side. It is about two 
inches deep, the base being at the surface and its limits being 
indicated by the anus within, the tuberosity of the ischium with- 
out, the transverse line in front, and the lower edge of the 
gluteus maximus muscle behind. The apex is above, and is 
formed by the coming together of two sides of the space, the 
inner side being a muscle, called levator ani, which is inserted 
into the side of the lower part of the rectum, while the outer 528 
DESCRIPTIVE ANATOMY. 
side is the obturator internus muscle. The levator ani muscle 
is thin and flat, and has a most peculiar origin, to understand 
which some preliminary remarks are necessary. When the 
transversalis fascia, which lies between the transversalis ab- 
dominis muscle and the parietal layer of the peritoneum, reaches 
the iliac fossa, where it covers the iliacus internus muscle, it 
takes the name of the iliac fascia, which, in turn, when it reaches 
the brim of the pelvis, assumes the name of pelvic fascia, and 
this descending into the pelvis when it reaches the commence- 
ment of the obturator foramen, splits into two layers, one of 
which, the external, passes over the inner side of the obturator 
internus, as the obturator fascia; while the other passes to the 
base of the bladder and the side of the rectum as the recto- 
vesical fascia. Now just in the interval left by the splitting of 
the pelvic fascia the levator ani rises, having internal to it the 
recto-vesical fascia and external, with a widening interval be- 
tween them, the obturator fascia. Besides this origin from the 
fascia, it arises posteriorly from the spine of the ischium and 
anteriorly from the back of the pubes. The ischio-rectal region 
thus described is found filled with adipose tissue, the absorp- 
tion of which, in long-continued, debilitating disease, is the 
cause of the sunken appearance seen there. 
Perineum-In the Male. 
The perineum is that subdivision of the outlet of the pelvis 
which lies in front of the transverse line. Its limits are as 
follows: In front the pubic arch; behind, the transverse line; 
on each side, the rami of the pubis and ischium. Crossing along 
its centre from behind forward, and continued on to the scrotum, 
is a ridge of the integument called the raphe. 
Upon careful dissection the perineum is found to be formed 
of the following constituents from the surface upward, viz.: 
1. Integument. 
2. Several layers of superficial fascia which in no wise differ 
from the general superficial fascia found beneath the integu- 
ment everywhere. 529 
THE OUTLET OF THE PELVIS. 
3. A layer of fascia called the superficial perineal fascia, 
since it is peculiar to the perineum, being attached to the rami 
of the ischium and the pubis on each side in front continuous 
with the dartos of the scrotum, and behind making a bend upon 
itself to become the deep perineal fascia, or triangular liga- 
ment, which is separated from the superficial perineal fascia 
by the root of the penis and the muscles connected with it. 
The triangular ligament is a continuation downward of the 
subpubic ligament. In front of it lies a chamber formed by its 
anterior (or inferior) face, and by the deep perineal fascia; 
while behind is a second chamber formed by its posterior (or 
superior) face and the parietal layer of the pelvic fascia. 
4. Removing the superficial perineal fascia there are exposed 
the root of the penis and its muscles. The root of the penis con- 
sists of the two crura attached, one on each side, to the rami 
of the pubis and ischium, and of the bulb of the corpus spon- 
giosum, which lies between these. 
The muscles which are exposed are three pairs: 
The transversus perinei, which arises on each side from the 
spot where the ramus of the ischium springs from the tuber- 
osity, and passes transversly inward to meet its fellow in the 
centre. The point where the two perinei are inserted into each 
other is called the perineal centre. It should be observed that 
the course of these muscles corresponds with the transverse line. 
The accelerator urinae arises from the perineal centre and 
from the raphe between it and its fellow. The greater portion 
of its fibres surround the corpus spongiosum to meet the oppos- 
ing muscle on the top of the corpus, but some of the fibres, 
posteriorly, are inserted into the deep perineal fascia and ramus 
of the pubis, while some in front are lost in the corpus cav- 
ernosum. Its chief action is to drive the urine forward by 
contracting on the corpus spongiosum, in which is the urethra. 
The erector penis arises from the rami of the ischium and 
pubis, and passing forward is lost on the upper aspect of the 
corpus cavernosum. 
After removing these muscles and the root of the penis the 
triangular ligament is displayed. This, as stated, is continuous 
at the transverse line with the superficial perineal fascia, the 530 
descriptive anatomy. 
line of reflection being around the posterior aspect of the trans- 
verse perineal muscles. From this point it passes forward to 
the arch of the pubes, attached on either side to the rami of 
the ischium and pubis. Just below the arch of the pubes it 
presents a small, round opening for the passage of the urethra. 
The triangular ligament was once called the deep perineal 
fascia. As we have already seen, it consists of but a single layer, 
having below it a chamber, limited inferiorly by the perineal fas- 
cia, and containing the root of the penis and certain muscles, 
vessels, and nerves; and above it another chamber, limited above 
by the parietal layer of the pelvic fascia, and containing vessels 
and nerves and the compressor urethrae muscle. 
The compressor urethrae arises from the ischio-pubic ramus, 
runs transversely inward and divides into two fasciuli, which 
pass above and beneath the urethra, where the muscles of the 
opposite side unite, thus completely surrounding the organ. 
INGUINAL HERNIA. 
inguinal hernia is the protrusion of some portion of the ab- 
dominal contents through the abdominal wall, making its way 
along the inguinal canal. The parts concerned are the lower 
fibres of the broad muscles of the abdomen, their superficial and 
deep coverings, and the structures composing the scrotum. 
There is no deep fascia investing the broad muscles of the 
abdomen. When the integument is removed, two layers of super- 
ficial fascia are seen, separated from each other by the super- 
ficial blood vessels and nerves, the deeper of the two being 
the stronger. The removal of the deep layer exposes the lower 
portion of the aponeurosis of the external oblique muscle, known 
as Poupart's ligament, which extends from the anterior superior 
spinous process of the ilium to the spine of the pubis, the inner 
portion forming the outer, or lower, pillar of the external, 
or superficial, abdominal ring. Poupart's ligament is folded 
upon itself, backward and upward, forming a groove directed 
upward and inward. To its posterior face is attached the trans- 
versalis fascia, where it becomes continuous with the iliac, while 
its anterior face is continuous with the fascia lata and has INGUINAL HERNIA. 
531 
adherent to it the deep layer of the superficial fascia. Before 
reaching the spine of the pubis, Poupart's ligament sends down- 
ward and backward a mass of fibres, with its base outward 
and apex inward, to be attached to the spine and pectineal line 
of the pubis, under the name of Gimbernat's ligament. Turning 
down Poupart's ligament we expose the combined origin of the 
internal oblique and transversalis muscles, which arches up- 
ward and inward, muscular, to form the conjoined arch, be- 
comes tendinous and arches downward and inward as the con- 
joined tendon, which is inserted into the crest and pectineal 
line of the pubis behind the superficial abdominal ring. The 
outer abutment of this arch is at the middle of Poupart's liga- 
ment, the inner one-half inch external to the spine of the pubis, 
while the centre of the arch is one-half inch above Poupart's 
ligament. Cutting away these structures we come to the trans- 
versalis fascia, behind which is the parietal layer of the peri- 
toneum, the two being separated by some loose connective tissue 
and fat. At the lower, inner, part of the aponeurosis of the 
external oblique muscle there is a triangular opening, caused 
by the divergence of the fibres of the aponeurosis, known as 
the superficial, or external, abdominal ring; the apex of the 
opening being directed upward and outward, its base downward 
and inward and corresponding to the crest of the pubis. The 
lateral boundaries of this ring are known as its pillars-internal, 
or superior, attached to the front of the symphysis pubis, ex- 
ternal, or inferior, attached to the spine of the pubis. The latter 
is simply the inner portion of Poupart's ligament. Around the 
margins of this ring the deep layer of the superficial fascia is 
attached, forming what is called the inter-cohimnar fascia. The 
two layers become continuous below with the dartos of the 
scrotum. The apex of the triangle is obscured by a few fibres 
of the aponeurosis, which cross the others at right angles and 
prevent a further divergence of the fibres, and consequent widen- 
ing of the triangle. These are called the inter-columnar fibres. 
About one and one-half inches above and external to this open- 
ing, nearly opposite the centre of Poupart's ligament, there 
is a hole in the transversalis fascia called the deep or internal 
abdominal ring, situated a little less than one-half an inch above 532 
DESCRIPTIVE ANATOMY. 
Poupart's ligament and internal to the outer abutment of the 
arch. Externally this ring is bounded by the conjoined arch, 
internally by the deep epigastric artery, below by Poupart's 
ligament. The ring does not exist in a healthy adult subject. 
Through this ring the testicle descends in the foetus, and to 
its margins is attached a prolongation of the transversalis fas- 
cia, the infundibuliform tube of fascia, which forms one of the 
coats of the hernia. Extending between the two rings there is a 
canal, about one and one-half inches long, the inguinal, or sper- 
matic, canal, which, in health, transmits the spermatic cord, 
in the male, or the round ligament, in the female, while, patho- 
logically, it transmits the gut in a hernia. 
The spermatic canal is limited internally by the superficial, 
externally by the deep, abdominal ring, and its walls are formed 
as follows: Below by the grooved upper surface of Poupart's 
ligament; above by the conjoined arch; in front by the aponeu- 
rosis of the external oblique; behind, by the transversalis fascia 
and parietal layer of peritoneum throughout its extent, while, 
for about its inner half, the conjoined tendon lies in front of 
those structures. The canal contains the neck of the infundi- 
buliform tube of fascia, arteries, nerves, lymphatics, and the 
duct from the testicle. 
On the visceral face of the peritoneum there may sometimes 
be seen a dimple which corresponds to the deep abdominal 
ring, and, internal to this, a ridge which is formed by the 
deep epigastric artery. The space between the ridge and the 
mid-line of the body is called the internal inguinal fossa, that 
external to the ridge the external inguinal fossa. 
The testicles, in their descent, enter at the deep ring, pass 
through the inguinal canal and make their exit at the superficial 
ring. The cause of this descent is not accurately known, but 
it is aided by the gubernaculum testis, a mass of unstriated 
muscular fibres, attached by one extremity to the testicle and 
by the other to the margins of the superficial abdominal ring. 
In its descent the testicle carries with it the structures closing 
the two abdominal rings. Thus, it presses upon the peritoneum 
at the deep abdominal ring, invaginates it and forces along a 
process of this membrane which becomes the deepest layer in- INGUINAL HERNIA. 
533 
vesting the testicle, and is known as the tunica vaginalis; next 
it forces along a process of the transversalis fascia, which, 
after the descent of the testicle, becomes attached to the deep 
ring forming the infundibuliform tube of fascia; then, while 
passing beneath the conjoined arch, muscular fibres, arranged 
in loops around the cord, are contributed, forming the cremaster 
muscle, whose ends are attached internally to the sheath of the 
rectus and externally to Poupart's ligament. These loops are 
attached to each other by fascia called the cremasteric fascia. 
Lastly, the testicle carries with it a process of the intercolumnar 
fascia, forming the external covering of the cord, which is, of 
course, covered by the superficial fascia and integument. Shortly 
after birth the tunica vaginalis is obliterated from the internal 
ring to within a short distance of the testicle. 
When, from weakening of the abdominal wall, or other cause, 
an inguinal hernia is produced, it usually follows the course 
of the testicle in its descent, and, hence, its coverings would be 
similar to those of the testicle. This form is known as an 
oblique inguinal hernia, subdivided into complete, when it es- 
capes from the superficial abdominal ring, and incomplete, or 
bubonocele, when it remains in the inguinal canal. A complete 
inguinal hernia pushes before it the peritoneum closing the 
deep abdominal ring, which forms the hernial sac, enters the 
inguinal canal, receiving an investment from the infundibuli- 
form tube of fascia and the cremaster muscle, passes through 
the superficial abdominal ring, carrying with it a covering fur- 
nished by the intercolumnar fascia, descends in front of the 
cord into the scrotum and is invested by the superficial fascia 
and the integument. In incomplete hernia the coverings cease 
at the superficial abdominal ring. 
When the peritoneal pouch is not obliterated there is a direct 
communication between the abdominal and scrotal cavities, and 
the peritoneal covering of the hernia is the tunica vaginalis. 
This form of hernia constitutes what is known as congenital 
hernia. 
In infantile hernia the pouch is closed at the deep abdominal 
ring only, and the gut descends behind the tunica vaginalis, 
having three peritoneal layers in front, viz.: the two layers of 534 
descriptive anatomy. 
the tunica vaginalis and one layer of the proper investing sac 
of the hernia. 
In the encysted form the gut, carrying its own sac, projects 
into the tunica vaginalis, leaving in front of it but two serous 
layers, viz.: one of its own sac and one from the tunica vaginalis. 
Direct Inguinal Hernia.-Hesselbach's triangle is bounded 
externally by the deep epigastric artery, internally by the rectus 
abdominis, below by Poupart's ligament. It is crossed by the 
conjoined tendon of internal oblique and transversalis muscles. 
Hernia may occur either external to or through this tendon. 
When the hernia is external to the tendon it follows a part 
of the inguinal canal and has the same coverings as an oblique 
inguinal hernia, except that the infundibuliform tube is replaced 
by another prolongation of the transversalis fascia. When 
through the tendon the latter is pushed before the gut, which 
has the same coverings as in the oblique form, except that the 
infundibuliform tube is replaced by another portion of the 
transversalis fascia, and the conjoined tendon replaces the cre- 
master muscle. Occasionally the hernia may split the tendon 
instead of pushing it before it. 
FEMORAL HERNIA. 
Definition.-The protrusion of an abdominal viscus through 
the femoral or crural ring. 
Parts Concerned.-Behind the femoral arch is found the 
upper border of the pubic bone, marked from within outward, 
by the angle, crest, spine, pectineal line, triangle and eminence, 
and the psoas groove. Stretching from the anterior superior 
spinous process of the ilium to the pubic spine and pectineal 
line, is Poupart's ligament, forming the femoral or crural arch. 
Gimbernat's ligament is the portion of Poupart's ligament which 
is inserted into the pectineal line. The other structures con- 
cerned are the iliac artery and vein and their sheath, the peri- 
toneum and fascia closing the mouth of the ring, the fascia lata, 
cribriform and superficial fasciae, and the integument. 
The space between Poupart's ligament and the upper border 
of the pubis is filled from without inward by the psoas and FEMORAL HERNIA. 
535 
iliacus muscles, the anterior crural nerve and the femoral sheath 
containing the femoral artery and vein and having in it an 
unoccupied space internal to the vein. This sheath is formed 
in front by the transversalis fascia, behind by the iliac fascia. 
Femoral Ring.-The femoral ring is the upper opening of 
the femoral canal. Internally it is bounded by the outer edge 
of Gimbernat's ligament; externally by a septum in the sheath 
separating the open space from the femoral vein; above is Pou- 
part's ligament; below, the upper border of the pubes and the 
origin of the pectineus muscle. The femoral canal extends down- 
ward in the sheath for about one inch, and is lined by a prolonga- 
tion of fascia which covers the vessels and is known as the 
fascia propria. The canal terminates by the contraction of the 
sheath so as to closely hug the vessels. The femoral ring is 
closed above by the peritoneum and a thin layer of fascia called 
septum crurale, or femorale, which usually has lying upon it 
a lymphatic gland. 
Blood Vessels.-Just beneath Poupart's ligament the ex- 
ternal iliac vessels terminate by becoming the femoral; but, 
before its termination, the external iliac artery gives off a large 
branch called the deep epigastric, which lies above and external 
to the femoral ring and between it and the deep abdominal ring. 
The external iliac vein lies to the outer side of the ring, so that 
in all cases there are blood vessels above and external to the 
ring. The deep epigastric artery sometimes gives off a branch 
called the obturator, which may descend next the iliac vein and 
on the outer side of the ring; but it sometimes passes inward 
and downward, arching above and internal to the femoral ring, 
which is thus surrounded by blood vessels on all sides except 
below. The epigastric also gives off a small pubic branch which 
lies above the ring, but is, from its size, unimportant. 
Fascia Lata.-The investing fascia of the thigh, or fascia 
lata, presents, about one inch below Poupart's ligament, an oval 
opening called the saphenous opening. The opening is closed 
in the recent state. It runs obliquely downward and outward, 
is about one inch in its vertical by three-quarters of an inch 
in its transverse diameter; its inner edge is straight and pro- 
longed outward behind the outer edge; its outer is curved, runs 536 
DESCRIPTIVE ANATOMY. 
downward and outward from Gimbernat's ligament to the in- 
ferior cornu and is called Hey's ligament or the falciform pro- 
cess of Burns. The external part of the fascia is known as the 
iliac portion, and is attached to the crest of the ilium and the 
outer portion of Poupart's ligament, sending inward a spur 
which is attached to the pectineal line, runs over the femoral 
vessels and forms the outer boundary of the saphenous open- 
ing. The inner part, called the pubic portion, is thin and weak, 
is attached to the ischio-pubic ramus, and is prolonged beneath 
the femoral vessels. The saphenous opening is covered by the 
skin and two layers of superficial fascia, of which the deep, 
under the name of cribriform fascia, becomes adherent to the 
margins of the opening. The cribriform fascia is attached more 
firmly below than above, and hence tends to direct a protruding 
gut upward. 
Course.-A femoral hernia passes downward through the 
femoral ring, thence down the canal as far as the saphenous 
opening, turns forward through this opening and then runs 
upward on the front of the thigh. The main causes of the 
ascent are the firmer attachment of the cribriform fascia below; 
the narrowing of the femoral canal and the movements of the 
thigh. 
Coverings.-Femoral hernia pushes before it, first the parie- 
tal layer of peritoneum and fat covering the femoral ring, then 
the septum femorale, fascia propria, cribriform fascia, super- 
ficial layer of the superficial fascia and, lastly, the skin. 
THE AXILLA. 
The space known by this name lies between the chest wall 
internally, the humerus externally, and the muscles in front 
and behind. In the skeleton only the apex of the space is com- 
plete, being bounded in front by the clavicle, behind by the 
upper border of the scapula, internally by the first rib. Below 
the apex the space corresponds to the upper five ribs internally, 
the scapula behind and the bottom of the bicipital groove ex- 
ternally. In the recent subject the space has the shape of a 
three-sided pyramid. The apex is above, the base below, and the THE ORGAN OF HEARING. 
537 
sharp angle external at the bicipital groove. The whole space 
is closed in by soft structures. The anterior wall is furnished 
by the pectoralis major, which covers the whole of the space, 
while beneath this, forming only the middle of the anterior wall, 
is the pectoralis minor. The posterior wall is formed by three 
muscles, subscapularis, teres major, and latissimus dorsi; but 
the order in which they come changes in different parts of the 
space. Near the inner wall the order, from above downward, 
is subscapularis, teres major, latissimus dorsi; but near the ex- 
ternal wall, owing to the fact that the tendon of the latissimus 
dorsi winds around the teres major and is inserted above it, 
the order is subscapularis, latissimus dorsi, teres major. The 
inner wall is formed by the upper six serrations of the serratus 
magnus muscle and the intercostal muscle corresponding to 
the upper five intercostal spaces. The lower border of the muscles 
which enter into the anterior and posterior boundaries of the 
axilla form the anterior and posterior axillary folds, of which 
the posterior is the thicker and more prominent. Stretching 
across from one fold to the other, and continuous with the in- 
vesting fascia of the arm, is a strong fascia which forms the 
floor of the space. The contents of this space are the brachial 
plexus of nerves and its terminal branches, the axillary artery 
and vein and their branches, lymphatic glands, and a quantity 
of areolar tissue and fat. 
THE ORGAN OF HEARING. 
The organ OF HEARING is connected with the temporal bone 
of each side, and properly speaking, consists of two organs, one 
to each side. In the prepared bone a portion is still preserved, 
for upon the base of the petrous portion of the temporal bone 
the bony portion of the external auditory meatus is seen; and 
on the posterior surface of the petrous portion the internal audi- 
tory meatus, at the bottom of which is seen the internal wall 
of the inner chamber perforated by numerous apertures. The 
external wall of the inner chamber is seen by looking into the 
external auditory meatus. On the anterior face of the petrous 
portion are seen the bulge of the superior semicircular canal 538 
DESCRIPTIVE ANATOMY. 
and just external to this a depression corresponding to the roof 
of the middle chamber, or tympanum, the floor of which is the 
jugular fossa, on the basilar face of the petrous portion of the 
temporal. 
The organ of hearing is described as consisting of three por- 
tions, or chambers, lying the one internal to the other, upon the 
base, and in the substance of the petrous portion of the temporal 
bone. These three chambers are known from without inward 
as: 1, external ear, consisting of three portions; (a) pinna, or 
auricle; (b) meatus auditorium externum; (c) membrana tym- 
pani; 2, middle ear, or tympanum; 3, internal ear, or labyrinth. 
External Ear. 
The external EAR consists of the three portions named above. 
Its function is to connect the sonorous vibrations and convey 
them to the middle ear, which in turn transmits them to the in- 
ternal ear, where they encounter the sentient nerve of hearing. 
The pinna, or auricle, is the expanded outer extremity of the 
external chamber found on the base of the petrous portion of 
the temporal bone, contracting to its termination in the external 
auditory meatus. It presents a very uneven surface and the 
various elevations and depressions have received individual 
names, The central concavity, leading to the external auditory 
meatus, is called the concha; the more or less folded margin, or 
rim, the helix; the pendant, lower, softer portion, the lobulus; 
the triangular prominence jutting out in front of the concha, 
the tragus; behind and somewhat below this, separated from it 
by a notch, is another projection, the antitragus; the curved 
elevation between the helix and the concha, or rather behind 
the concha, is the anti-helix, which divides superiorly, enclosing 
a depression called the fossa ovalis; the deeply sunken surface 
between the helix and the anti-helix is the fossa scaphoidea, or 
innominata. 
The pinna varies greatly in different people, and this is espe- 
cially true of the lobule. In structure it consists of a plate of fi- 
bro-cartilage, whose folds produce the depressions and elevations 
mentioned. This cartilage is covered by integument and alveolar THE ORGAN OF HEARING. 
539 
tissue, supporting various insignificant muscles, intrinsic, in- 
tended to vary its shape, and giving attachment to other small 
muscles, extrinsic, intended to move the pinna. Of the latter 
some few people have use, but the former never act to produce 
visible effect. The cartilage is not continuous throughout the 
auricle, for it is altogether wanting in the lobule and, besides, 
presents several fissures which have received names. The pinna 
is held in position by the integument, by the extrinsic muscles 
mentioned above, and by two ligaments, anterior and posterior. 
The anterior extends from the helix to the zygoma; the posterior, 
from the concha to the mastoid process. Besides these there are 
several small ligaments passing from one part of the cartilage 
to another, the largest of which is that between the tragus 
and helix. 
The external auditory meatus is the canal, which extends 
from the concha to the tympanum, from which it is separated 
by the tympanic membrane. It is rather more than an inch 
in length, its direction being inward and slightly forward, and 
its course somewhat curved, with its convexity upward. It is 
smaller in the centre than at either end. It consists of an ex- 
ternal cartilaginous portion, taking up one-third of its length, 
and an internal, osseous portion, taking the remaining two- 
thirds. The osseous portion terminates internally at an oblique 
groove for the attachment of the membrana tympani. This por- 
tion can be seen in the dried bone, although the septum in the 
bottom is of course absent. The outer extremity is rough and 
prominent for the attachment of the cartilaginous portion. It 
is lined throughout by the integument which, toward the ex- 
terior, is studded with hairs and contains glands for the secre- 
tion of the ear wax. The hairs and wax are intended to ob- 
struct the entrance of insects, etc. 
The membrana tympani is the septum separating the ex- 
ternal from the middle chamber, being situated at the inner 
extremity of the external auditory meatus, attached to the ob- 
lique groove there found. It is fragile, semi-transparent, nearly 
round, oblique in its direction from above downward and in- 
ward, striking the floor at an angle of 45°, and is seen to bulge 
toward the tympanum, having a corresponding concavity ex- 540 
DESCRIPTIVE ANATOMY. 
ternally. Its frame work is fibro-elastic, consisting of radiat- 
ing and concentric fibres, the latter especially seen near its cir- 
cumference ; it is covered externally by the exceedingly sensitive 
integument lining the external auditory meatus. Internally it 
is coated by mucous membrane of the tympanum. 
Middle Ear. 
The middle ear, chamber, or tympanum, lies in the petrous 
portion of the temporal bone, separated, externally, from the 
meatus auditorius externus by the membrana tympani; and 
separated, internally, from the inner chamber, or labyrinth by 
a bony wall; its roof corresponds to the depression on the ante- 
rior face of the petrous bone; its floor to the jugular fossa on 
the basilar face of that bone. Its anterior wall is a bony par- 
tition interposed between it and the internal carotid artery, and 
its posterior wall is the cellular substance of the mastoid por- 
tion of the temporal bone. Owing to the obliquity of the inner 
and outer walls, the tympanum is much narrower transversely, 
below than above. The length of its roof from without inward 
is about three lines, the floor being scarcely more than one line. 
It presents for examination six walls, two of which-floor and 
roof-have nothing noteworthy. The outer wall has been de- 
scribed as the membrana tympani, having attached to it a chain 
of bones, which extends to the inner wall. 
The internal wall is the bony partition between the tympanum 
and the labyrinth, upon which are seen the following appear- 
ances: (a) a ridge at its upper part corresponding to the aque- 
duct of Fallopius; (b) just beneath this a kidney-shaped aper- 
ture, opening into one of the apartments of the labyrinth, called 
the fenestra ovalis. This is closed during life by a membrane 
to which is attached the foot of the stapes; (c) below this is a 
bulging surface known as the promontory; (d) beneath this is a 
second opening oval, or triangular in shape, called the fenestra 
rotunda, which is likewise closed by a membrane and establishes 
communication with another part of the labyrinth called the 
cochlea. THE ORGAN OF HEARING. 
541 
The posterior wall presents several small openings into the 
mastoid cells and the opening for the entrance of the chorda 
tympani (iter chordae posterius) which crosses the tympanum 
to gain exit on its anterior wall. There is also a conical pro- 
jection, the pyramid, which has at its summit an opening for the 
stapedius muscle. 
On the anterior wall are seen: (a) the fissure of Glaser; (b) 
the opening of exit of the chorda tympani (iter chordae anterius, 
or canal of Huguier) ; (c) two small openings, separated by a 
thin plate of bone, the upper being the opening for the tensor 
tympani, the lower the opening for the Eustachian tube, and the 
dividing septum, the cochleariform process. Stretching across the 
tympanum from the membrana tympani, externally to the fenes- 
tra ovalis, internally, are seen three small bones, malleus, incus, 
and stapes. The malleus is the outermost of the three, resting 
against the membrana tympani externally and articulating with 
the incus internally. It consists of a head, for articulation with 
the incus, a neck, and three processes. One of the processes is 
called the handle, and lies imbedded in the membrana tympani, 
half way to the floor from above downward. Another, the long 
process, processus gracilis, passes downward to the fissure of 
Glaser; while the third, the short process, bulges outward from 
the neck. The incus is so called from its resemblance to an anvil. 
It consists of a body, for articulation with the head of the mal- 
leus, and two processes. The short process passes backward 
to the opening of the mastoid cells in the posterior wall; the long, 
passes downward to articulate with the head of the stapes, ter- 
minating in an enlargement, called the os orbiculare. The 
stapes, stirrups, projects inward from the os orbiculare with 
which it articulates by a head. Succeeding the head comes the 
neck, and diverging from this are the two crura, one to either 
side, which are connected at their distal extremity by a plate, 
called the foot, which is exactly fitted into the fenestra ovalis. 
When the child is born those bones have attained nearly their 
full size. They are held together by ligaments and give at- 
tachment to several small muscles which are intended to move 
the bones on one another and thus relax, or tighten the mem- 
brana tympani, or the membrana fenestra ovalis. This latter 542 
DESCRIPTIVE ANATOMY. 
membrana is in fact composed of two layers, and the fenestra 
ovalis is closed successively by the following parts from without 
inward, viz.: 1, the mucous membrane of the tympanum; 2, 
beneath this the foot of the stirrup; 3, on the labyrinthine sur- 
face this foot is coated by the serous membrane lining the 
labyrinth. The arrangement for closing the fenestra rotunda 
is similar in consisting of three elements: 1, a fibrous membrane 
coated by (2) the mucous membrane of the tympanum ex- 
ternally and (3) internally by the serous membrane of the laby- 
rinth. It is constructed so much like the membrana tympani 
that it has been called the membrana tympani secundaria. The 
ossicula auditus are held to one another and in position by 
means of small ligaments. The head of the malleus is held to 
the body of the incus by a capsular ligament; and another cap- 
sular ligament binds together the os orbicularis and the head 
of the stapes. The ligaments holding the bones in position are 
three in number: 1, the foot of the stapes is held to the fenestra 
ovalis by means of ligamentous fibres; 2, there is a suspensory 
ligament of the malleus consisting of a few ligamentous fibres 
passing between its head and the root of the tympanum; 3, a 
band of fibres attaches the short process of the incus to the 
opening of the mastoid cells. These bones, thus permitted mo- 
tion by means of the ligaments, are moved not only by the 
vibrations of the membrana tympani but by two small muscles, 
viz.: The tensor tympani springs from the apex of the basilar 
surface of the petrous bone and the upper aspect of the car- 
tilaginous portion of the Eustachian tube and enters the opening 
in the tympanum known by. its name, just above the processus 
cochleariformis, which separates it from the opening of the 
Eustachian tube; it also derives a few fibres from the canal it 
traverses. When it reaches the anterior wall of the tympanum 
its tendon turns outward and is inserted into the malleus at the 
junction of the manubrium and long process of the malleus. 
The stapedius is far the smallest muscle in the body. It arises 
within the hollow pyramid, on the posterior wall of the tym- 
panum, emerges from the opening on the summit of the pyra- 
mid and is inserted by a tendon into the neck of the stapes. THE ORGAN OF HEARING. 
543 
The action of the stapedius is to regulate the pressure of the 
foot of the stapes against the fenestra ovalis. 
Eustachian Tube. 
The eustachian tube is a canal which establishes communi- 
cation between the air in the tympanum and the outside atmos- 
phere. It passes from the anterior wall of the tympanum, where 
its opening is seen just beneath the processus cochleariformis, 
downward, forward, and inward, to terminate in the pharynx, 
just behind the opening of the posterior nares. Its lower third 
is cartilaginous; its upper two-thirds osseous. 
Internal Ear. 
The internal EAR, or labyrinth, is the innermost of the 
three chambers, which constitute the organ of hearing, and is 
intended for the terminal ramifications of the auditory nerve, 
which reaches it through the internal auditory meatus, on the 
centre of the posterior face of the petrous bone, and for the re- 
ception of the vibrations communicated from the air and trans- 
mitted through the tympanum. It consists of an osseous and 
a membranous labyrinth, the osseous being divided into three 
chambers, which, however, communicate with one another. 
These three parts are placed one behind the other; the ante- 
rior is called the cochlea, the middle the vestibule, the posterior 
the three semicircular canals. They are all lined by a serous coat. 
Vestibule. 
The vestibule is a three-cornered cavity, having communica- 
tion with the tympanum through the fenestra ovalis. Each 
corner is called a ventricle, and the three are known as anterior, 
superior, and posterior. In the anterior are seen the following 
objects: 1, a depression, called fovea hemispherica; 2, a number 
of minute apertures, called the macula cribrosa; 3, a ridge, the 
eminentia pyramidialis; 4, the opening into the cochlea, scala 
vestibule. In the superior we have: 1, a depression-the fovea 544 
DESCRIPTIVE ANATOMY. 
hemi-elliptica; 2, the two openings of semicircular canals- 
the dilated extremities of the superior and horizontal. The pos- 
terior presents: 1, a depression-fovea sulciformis; 2, the open- 
ing of the aqueduct of the vestibule; 3, the dilated extremity of 
the oblique semicircular canal, the common aperture for this 
canal, and the superior and the opening of the horizontal canal. 
Semicircular Canals. 
These canals are channels hollowed in the petrous portion of 
the temporal bone. They are three in number, each about one- 
twentieth of an inch in diameter, and placed at right angles to 
one another. Each forms rather more than a semicircle, and 
presents near one extremity an enlargement, called the ampulla, 
and opens by both ends into the vestibule. The three canals are 
called: 1, superior, which is vertical in direction and produces 
the ridge seen on the anterior face of the petrous bone; 2, the 
posterior, or oblique, which is also vertical; 3, the external, or 
horizontal. These three canals present but five openings into 
the vestibule, owing to the fact that the posterior and superior 
have a common opening into the posterior corner of the vesti- 
bule. The other openings were mentioned in the description 
of the vestibule-three being into the posterior and two into 
the superior corner. 
Cochlea. 
The cochlea lies in front of the vestibule and by the side of 
its base forms the promontory, seen on the inner wall of the tym- 
panum. When entire it resembles a snail's shell, and may be 
described as consisting of a tube divided into two apartments 
by a longitudinal septum, one end of the tube being closed and 
much smaller than the open end from which it rapidly tapers. 
The septum is not complete, for it fails to reach to the small, 
closed end, thus allowing a communication between the two 
chambers. This tube is coiled by two turns and a half around 
a stem, or tapering pillar, called the modiolus. The septum sub- 
dividing the two chambers, which are called scalae, is named the THE ORGAN OF HEARING. 
545 
lamina spiralis. It consists of two layers, between which is a 
narrow space, called scala media, and it terminates in a hook- 
like projection called the hamulus. When examined closely the 
lamina spiralis is seen to consist of three structures; the por- 
tion next the modiolus is bony, farther out it is membranous, 
and the outermost portion is muscular, and sometimes called 
the cochlearis muscle. The small space, existing between the 
extremity of the lamina spiralis and the cupola, is called the 
helicotrema; it establishes communication between the two 
chambers, one of which is called the scala tympani, the other 
the scala vestibuli. The scala vestibuli is seen to communicate, 
at the base of the cochlea, next the vestibule, with the anterior 
corner of the vestibule. The scala tympani communicates with 
the tympanum, by means of the fenestra rotunda. The modio- 
lus is the tapering pillar around which the two scalae wind. In 
its centre there is a canal called the tubulus centralis modioli. 
Its base is next the vestibule. 
Membranous Labyrinth. 
Beside the parts above described, the labyrinth contains others 
for, within each semicircular canal, is a membranous counter 
part, two-thirds smaller, separated from the bony wall by liquid. 
The membranous canals present the same dilations at one end, 
ampullae, as the bony. 
In the vestibule also are two membranous sacs, one above 
the other. The upper one receives the openings of all the semi- 
circular canals and lies in the fovea hemi-elliptica. It is called 
utriculus, or sacculus, proprius. In the membranous labyrinth, 
as the above parts are collectively called, are found crystalline 
particles, carbonate and phosphate of lime, called ear-dust, or 
otoliths. 
The auditory nerve gains the labyrinth through the internal 
auditory meatus. At the bottom it divides into a vestibular and 
a cochlear branch, the latter dividing into filaments which run 
in channels in the modiolus and turn outward to ramify in the 
lamina spiralis. The vestibular branch divides into three, one 546 
DESCRIPTIVE ANATOMY. 
for each of the membranous sacs, and one for the semicircular 
canals. 
THE ORGAN OF VISION. 
The organ of vision is situated in the orbits, two conical 
cavities found on the face. Like the organ of hearing, it con- 
sists of two similar portions, one on each side, called the eye- 
ball and its appendages. 
Appendages of the Eye. 
The appendages of the eye, tutamina oculi, are mere acces- 
sories to the true organ of vision, the eye-ball, for the purpose 
of protection and ornament. 
The, eyebrorv is a prominence of the integument, curved 
covered with hair, and situated above each orbit. It is intended 
for ornament and protection from dust, perspiration and too 
vivid light, and to break the force of any blow falling on the 
front of the orbit. 
The eyelids consist of two movable curtains, which are con- 
stantly playing over the front of the eyeball. The aperture, 
which separates the two lids, one called upper, superior pal- 
pebra, the other lower, inferior palpebra, is known as the pal- 
pebral fissure and can be closed or opened at pleasure. The 
two lids meet externally at an acute angle called the external 
canthus; internally when they seem about to meet they refrain 
from doing so, and the interval between is prolonged inward 
towards the nose for some distance before forming the internal 
canthus. The triangular space thus left between the lids at the 
inner canthus is called the lachrymal lake, lacus lachrymalis, 
in which is seen a reddish, conical projection, called the car- 
uncle, which is bounded externally by a curved fold of mucous 
membrane, called the plica semicircularis. The concavity of this 
fold is external. 
At the commencement of the lachrymal lake, just where the 
two lids are apparently about to unite, there is a projection THE ORGAN OF VISION. 
547 
from the edge of each lid, called the lachrymal papilla, or tuber- 
cle, on the summit of each of which is an opening, the punctum 
lachrymale. The free edge of each lid is provided with several 
rows of short curved hairs, the eyelashes, intended for orna- 
ment, to render the contact of the lids more intimate and to 
protect against dust, etc. In structure the eyelids consist of the 
following parts: externally there is a layer of thin, loose skin 
with subjacent areolar tissue; internally, a layer of mucous 
membrane called the conjunctiva, which not only lines the inner 
surface of the lids, but is reflected over the front of the ball- 
palpebral and ocular portions. The palpebral portion is studded 
with papillae. Just beneath the integument, on the outer surface 
of the lid, is a pale thin muscle, the orbicularis palpebrarum, so 
named from the fact that it is somewhat round, passes from one 
lid to the other, and surrounds the palpebral fissure, its function 
is to close the lids. Beneath the orbicularis palpebrarum, in 
each lid is a curved plate of cartilage, about an inch in length, 
called the tarsal cartilage. The superior is the larger, and is 
semi-lunar in shape; the inferior is much the narrower and oval. 
The two are attached along their circumference to the edge of 
the orbit by ligamentous fibres. Externally, they are held to the 
outer angle of the orbit by a ligament called the external pal- 
pebral, or tarsal ligament; internally, they terminate in a liga- 
ment, called the tendo oculi, which holds them to the edge of the 
orbit. Lying on the posterior surface of the lids between them 
and the mucous membrane, and opening on the edge of the lids 
is a number of vertical, beaded bodies, the Meibomian glands, 
the secretion from which is discharged on the edge of the lids. 
There are thirty of these glands for the upper lid, but a smaller 
number for the lower. 
Lachrymal apparatus. Lying in the depression seen on the 
orbital plate of the frontal bone, just behind the external angu- 
lar process, is the lachrymal gland. It is about the size and 
shape of an almond and rests on the posterior part of the upper 
tarsal cartilage. The ducts, seven to twelve in number, dis- 
charge the secretion of the gland, tears, on the surface of the 
conjunctiva, whence it is constantly swept toward the inner can- 
thus of the eye by the frequent movement of the lid; there it 548 
DESCRIPTIVE ANATOMY. 
disappears in the lachrymal puncta from each of which there 
leads a small canal called the lachrymal canaliculi. The upper 
first ascends, then bends inward to terminate in the nasal, or 
lachrymal duct; the lower first descends, then turns inward to 
terminate in the nasal duct beside the superior. The nasal duct 
extends a little way above the openings of the canaliculi in a 
portion, called the lachrymal sac; and from this point the duct 
extends downward, outward, and slightly backward, to termi- 
nate in the inferior meatus of the nose. 
Globe of the Eye. 
The eyeball is situated in the front part of the orbit, em- 
bedded in a mass of fat. It is nearly globular, its antero-pos- 
terior diameters being one inch and its transverse nine-tenths 
of an inch. Posteriorly it receives the optic nerve, at a point 
about one-tenth of an inch to the nasal side of the centre. The 
ball consists of concentric layers enclosing a bag of liquid, which 
forms about four-fifths of it. These coats or layers are sclerotic, 
choroid and retina. 
Sclerotic Coat. 
The SCLEROTIC, familiarly known as the white of the eye, is 
a dense fibrous membrane, which serves as a protecting envelope 
for the rest of the eyeball. Its anterior one-sixth is wanting, 
the aperture being filled by a transparent membrane, the cornea. 
Posteriorly, the sclerotic is perforated by the optic nerve, not 
en masse, for the nerve splits into a number of fibres, which 
pierce the coat separately, producing the appearance known as 
the lamina cribrosa, the fibrous sheath of the nerve becoming 
continuous with the sclerotic, while in front the sclerotic is con- 
tinuous with the cornea. 
Cornea. 
The CORNEA forms the anterior one-sixth of the first invest- 
ment of the eyeball. It forms a segment of a smaller sphere THE ORGAN OF VISION. 
549 
than the sclerotic, and being more convex, it causes the increase 
of the antero-posterior diameter over the transverse. The 
cornea, instead of being opaque, like the sclerotic, is transparent, 
and its circumference is received beneath the anterior bevelled 
edge of the sclerotic with which it is continuous in some of the 
structures. It consists of five layers. The anterior surface is 
an epithelial layer, derived from the conjunctiva; the posterior 
layer is also epithelial, the lining membrane of the anterior 
chamber. Next each of these is found a layer of elastic tissue, 
the two layers constituting what is called the elastic cornea, and 
separating these is a layer of fibrous tissue, called the cornea 
propria, which can be split into sixty layers of spindle-shaped 
cells with branching intervals, in which circulates the colorless 
plasma of the blood. It is with this cornea propria that the 
sclerotic is continuous. The cornea is of varying convexity in 
different people and at different periods of life. It is more con- 
vex in youth, and becomes less so in old age, at which period 
there is often seen around the cornea a yellowish band, called 
arcus senilis. 
Choroid. 
The CHOROID lies within the sclerotic, with which it is con- 
nected by areolar tissue, sometimes called lamina fusca, which 
is pierced by the optic nerve. At the point in front where the 
sclerotic ceases the choroid terminates in a flattened membrane, 
the iris, which, in its centre presents a round aperture, the pupil. 
The choroid consists of three layers, the outer two red and the 
inner black. Between the two red and the black layers some 
make a fourth layer, the membrana limitans. The external red 
layer is called the venous layer; the internal red layer the capil- 
lary or arterial layer, or the tunica Ruyschiana. The internal 
layer, or membrana pigmenti, or tapeta, is of a black color, con- 
sisting of cells, filled with coloring matter. On the anterior sur- 
face of the choroid, just around its anterior margin, is a whitish 
band, one-fortieth of an inch wide, called the ciliary ligament, 
which binds together the cornea and sclerotic and the choroid 
and iris. Extending back, about one-eighth of an inch, on the 550 
DESCRIPTIVE ANATOMY. 
anterior aspect of the choroid, is a gray circular band, called the 
ciliary muscle. On the posterior aspect of the front of the 
choroid are about sixty ridges, diverging from the rim of the 
choroid, called the ciliary processes. 
Iris. 
The IRIS is the thin flat membrane, which continues the cho- 
roid in front. In its centre is seen the opening, called the pupil. 
The various colors of the iris are due to the difference of color 
of the pigmentary matter found in its cells and to the varying 
arrangement of the blood vessels. The color is darkest usually 
near the centre. 
Towards the middle of the iris is a circle of little shaggy pro- 
jections. The foundation of the structure of the iris is fibrous 
tissue, consisting of circular and radiating fibres interposed be- 
tween which are pigment cells. In front and behind this fibrous 
layer is a layer of pigment cells. In the iris, are also seen un- 
striated muscular fibres, some circular around the pupil, and 
some radiating toward the circumference; by the action of these 
fibres the pupil is constantly dilating and contracting. Blood 
vessels and nerves ramify throughout the structure. On the pos- 
terior surface the iris consists of a black layer, called the uvea, 
which is, in fact, a continuation of the membrana pigmenta of 
the choroid. 
Anterior chamber-Between the iris and pupil behind, and 
the cornea in front is a small cavity, called the anterior chamber. 
Posterior chamber-Between the iris and pupil in front, and 
the lens behind is another, smaller cavity, called the posterior 
chamber. These two contain a liquid, called the aqueous humor, 
and they communicate through the pupil, after the sixth month 
of fcetal life, up to which time the pupil is closed by a mem- 
brane, called the pupillary. Both chambers are lined by a mem- 
brane which secretes the aqueous humor. THE ORGAN OF VISION. 
551 
Retina. 
The retina is the innermost of the three coats of the eye, lying 
just within the choroid. It is wanting in front, even for a 
greater distance than the two preceding layers, for it ceases, as 
it reaches the ciliary processes in a rough jagged margin, called 
ora serrata, and is continued thence to the crystalline lens by a 
vascular membrane, called the suspensory ligament of the lens. 
The outer surface of the ligament is fluted to correspond with 
the cilliary processes, against which it rests. 
The retina is non-resisting and translucent, being partially 
formed by the expansion of the optic nerve, with which it is con- 
tinuous posteriorly. 
Exactly in the centre, posteriorly, is a round, yellowish spot, 
called the macula lutea, and in the centre of this spot a depres- 
sion called fovea centralis. About one-tenth of an inch to the 
inner side of this is seen the termination of the optic nerve- 
optic disk, or papilla-showing in its centre the arteria centralis 
retinse, breaking up into branches. From this point forward 
the retina gradually thins to its termination. 
The Vitreous Humor. 
Just within the retina is a bag, called the hyaloid membrane, 
containing a liquid, called VITREOUS HUMOR. This is similar in 
composition to the aqueous humor, being 98% water. Travers- 
ing the centre of this, in the foetus, is a branch of the arteria 
centralis retinae, making its way to the lens, called the capsular 
artery. It disappears at birth. 
The Crystalline Lens. 
Indenting the front of the hyaloid membrane is found a doubly 
convex transparent body, called the CRYSTALLINE lens. Its pos- 
terior surface is much more convex than the anterior, the latter 
forming the posterior wall of the posterior chamber. The lens 
forms only the bulging portion of the wall, the circumference of 
which is formed by the suspensory ligament of the lens, which 552 
DESCRIPTIVE ANATOMY. 
extends from the ora serrata of the retina to the rim of the 
lens. This ligament is formed of two layers, and when it lays 
hold of the lens it leaves a circular canal around it, called the 
canal of Petit. The lens is invested by a transparent homo- 
geneous, elastic membrane, the capsule of the lens. In structure 
the lens consists of a series of concentric layers of parallel fibres, 
which gradually harden towards the centre of the lens. It can 
also be split into three triangular segments, which meet by their 
apices in the centre of the lens. 
In youth the lens is more convex and much softer than in old 
age, as it gradually becomes, with advancing life, firmer and less 
convex. INDEX. 
A. 
Abdomen, boundaries of 176 
Abdominal aorta 361 
branches of 362 
viscera, relations of 181 
Abductor minimi digiti (hand) 281 
" " (foot) 303 
pollicis (hand) 280 
" (foot) 303 
Accelerator urinae 529 
Accessorius muscle 304 
Acetabulum 47 
Acromial region 260 
thoracic artery 341 
Acromio-clavicular joint 135 
Acromion process 26 
Alar ligaments 158 
thoracic artery 341 
Alimentary canal 165 
Anconeous muscle 277 
Angular convolutions 434 
Ankle joint 160 
Anterior ethmoidal cells 86 
fossa skull 106 
region skull 109 
Antrum of Highmore 91 
Anus 197, 527 
Aorta 353 
abdominal 361 
ascending 353 
branches of 355 
transverse 354 554 
Index. 
descending 358 
Appendages of eye 547 
Appendix, right auricle 229 
left auricle . 231 
vermiform 194 
Aqueductus vestibuli 77 
Fallopii 77 
Sylvius 447, 450, 501 
Aqueous humor 551 
Arachnoid of brain 427 
cord 455 
Arm, arteries of 342 
fascia . 264 
lymphatics 424 
muscles 264 
nerves 467 
veins 409 
Artery, or arteries 315 
acromial thoracic 341 
alar thoracic 341 
angular 324 
anterior cerebral 399 
choroid 400 
ciliary 399 
communicating 399 
articular of knee 384 
axillary 338 
basilar 334 
brachial 343 
calcanean 385 
carotid, common, left 356 
" " right 317 
external 320 
branches 321 
internal 395 
circumflex, arm 342 
thigh 381 
colica dextra 370 Index. 
555 
media 370 
sinistra 370 
coronary, heart 355 
lips 324 
digital (hand) 348 
(foot) 386 
epigastric 376 
facial 323 
femoral 377 
deep 380 
gastric 365 
gastro-epiploica dextra 366 
sinistra 367 
gluteal 395 
hepatic 366 
ileo-colic 369 
iliac, common 374 
iliac, external 375 
internal 390 
innominata 356 
internal mammary 336 
maxillary 327 
plantar 386 
intestini tenuis 368 
lateralis nasi 324 
lingual 322 
long thoracic 341 
obturator 391 
occipital 324 
ophthalmic 397 
plantar 385 
perineal • 393 
peroneal 386 
phrenic 363 
popliteal ' 382 
radial, forearm 346 
" hand and wrist 350 
renal 373 556 
Index. 
sciatic 392 
subclavian, right 329 
left 357 
temporal, superficial 326 
thyroid axis 335 
tibial, anterior , 387 
tibial, posterior 384 
transversalis colli 336 
ulnar, forearm 347 
" hand 348 
vertebral 332 
Articulations in general 121 
Articulation, ankle 160 
atlo-axoid 127 
calcaneo-astragaloid 162 
cuboid 163 
carpal 145 
costo-vertebral 148 
costo-sternal 148 
elbow 141 
hip 150 
knee 154 
occipito-atloid 128 
pelvis 131 
radio-carpal (wrist) 143 
ulnar 139 
shoulder 136 
sterno-clavicular 133 
temporo-maxillary 147 
tibio-fibular 160 
vertebral column 124 
wrist 143 
Arytenoid cartilage 220 
Ascending colon 184 
Astragalus ' 60 
Atlas 10 
Auditory nerve 510 
Auricle, of ear 538 Index. 
557 
heart 229 
Axilla 537 
Axillary artery 338 
vein 412 
Axis 11 
B. 
Base of brain 438 
skull, superior surface 103 
inferior surface 106 
Basilic vein 411 
Bladder, relations in female 214 
male 190 
description of 204 
Bone, or Bones: 
astragalus 60 
atlas 10 
axis 11 
calcaneum 59 
carpal 34 
clavicle 22 
coccyx 15 
cranial 69 
cuboid 62 
ethmoid 84 
articulations of 116 
femur 50 
fibula 57 
frontal 72 
articulations of 114 
humerus 26 
hyoid 68 
ilium 43 
inferior maxillary 96 
turbinated 88 
articulations of 119 
innominata 43 558 
Index. 
Bone, or bones (Continued) : 
ischium 45 
lachrymal 87 
articulation of 120 
malar 89 
articulations of 120 
nasal 86 
articulations of 117 
occipital 69 
articulations of 113 
palate 94 
articulations of 118 
parietal 71 
articulations of 114 
patella 53 
radius 32 
rib 18 
sacrum 13 
scaphoid (hand) 34 
(foot) 63 
scapula 23 
sphenoid .... 7 79 
sphenoid, articulations of 115 
sternum 17 
superior maxillary 90 
articulations of 117 
tarsal 59 
temporal 74 
articulations of 115 
tibia 54 
ulna 29 
vomer 89 
articulations of 119 
zygomatic 89 
Brain: 
base of 438 
convolutions 430 
interior 440 Index. 
559 
membranes 425 
Bronchi 223 
C. 
Capsular ligament, hip 151 
shoulder 137 
Cerebellum 451 
Cerebrum 429 
Clavicle 22 
Coccyx 15 
Coeliac axis 364 
Coraco-clavicular ligament 136 
Corpus callosum 441 
fimbriatum 445 
Costal cartilages 21 
Cranial bones 69 
nerves 497 
Cranial nerves, eighth 510 
eleventh 516 
fifth 502 
first 499 
fourth 501 
ninth ; 510 
second 500 
seventh 508 
sixth 507 
tenth 512 
third 501 
twelfth 516 
Crystalline lens 551 
D. 
Duodenum 182 560 
Index. 
E. 
Ear 537 
Elbow joint 141 
Epiglottis 217 
Ethmoid bone 84 
articulations of 116 
Eye 546 
tunics of 548 
muscles of 312 
F. 
Face, arteries of ' 323 
bones 86 
muscles 313 
Fauces, isthmus of 166 
Female generative organs 211 
Femoral artery 377 
canal 536 
hernia 534 
Fifth nerve 502 
First nerve 499 
Fissures of brain 430 
Foot, arteries of 386 
bones 59 
muscles 299 
ligaments 162 
nerves 495 
Fossa, spheno-maxillary 102 
of skull, anterior 106 
middle and posterior 107 
temporal 101 
zygomatic 102 Index. 
561 
G. 
Ganglion, cervical • 518 
ciliary, or ophthalmic 524 
Meckel's 524 
otic 525 
semilunar 521 
H. 
Hand, bones of 34 
ligaments 143 
Heart 227 
Hernia, femoral 534 
inguinal 530 
Hip joint 150 
Humerus 26 
I. 
Ileum 194 
Iliac arteries, common 374 
external 375 
internal 390 
veins, external 403 
internal 404 
Ilium 43 
Inferior vena cava 404 
Inguinal canal 532 
hernia 530 
Intestine, large, description of 194 
small, description of 193 
relations of 182 
Ischio-rectal region 527 
Ischium 45 
Island of Reil 435 562 
Index. 
K. 
Kidney, relations of 189 
structure of 202 
Knee joint 154 
L. 
Larynx, cartilages of 215 
ligaments of 217 
muscles of 219 
Ligaments 121 
acromio-clavicular 135 
ankle 160 
atlanto-axoid 127 
calcaneo-astragaloid 162 
" cuboid 163 
" scaphoid 164 
common vertebral 124 
costo-vertebral 148 
of elbow 141 
of hip 150 
of jaw 147 
of knee 154 
radio-carpal 143 
radio-ulnar 139 
sacro-sciatic 131 
of shoulder 136 
tibio-fibular 160 
Liver, relations of 186 
structure of 198 
Lungs, relations of 224 
Lymphatics 422 
arm 423 
cervical 424 
lower extremity 423 
thorax 425 Index. 
563 
M. 
Malar bone 89 
articulation of 129 
Manubrium 17 
Mediastinum 226 
Medulla oblongata 448 
Membranes of brain 425 
cord - 455 
Munro, foramen of 446 
Mouth 165 
Muscle, or Muscles 233 
abductor minimi digiti (hand) 281 
(foot) 303 
pollicis (hand) 280 
hallucis 303 
accessorius 304 
abductor brevis 294 
longus 294 
magnus 294 
anconeus 277 
arytaenoideus 220 
biceps (arm) 265 
(thigh) 291 
flexor cruris 287 
brachialis anticus 266 
brachio-radialis 274 
buccinator 314 
compressor naris 308 
constrictor pharyngeus, inferior 172 
medius 172 
superior 173 
coraco-brachialis 265 
crico-arytoenoideus lateralis 220 
posticus 220 
crico-thyroid 219 
deltoid 260 564 
Index. 
Muscle, or Muscles (Continued) : 
diaphragm 239 
digastric 246 
erector spinae 255 
extensor brevis digitorum 302 
extensor carpi radialis brevior 275 
longior 274 
ulnaris 276 
communis digitorum 275 
indicis 278 
longus digitorum 299 
minimi digiti 276 
ossis metacarpi pollicis 278 
primi internodii pollicis 278 
proprius pollicis 300 
secundi internodii pollicis 278 
of face 306 
flexor brevis minimi digiti (hand) 281 
flexor brevis minimi digiti (foot) 305 
digitorum 303 
pollicis (hand) 280 
(foot) 305 
flexor carpi radialis 270 
ulnaris 270 
longus digitorum 298 
pollicis (hand) 272 
(foot) 297 
ossis metacarpi pollicis 280 
profundus digitorum 271 
sublimis digitorum 271 
gastrocnemius 296 
gemellus, superior 285 
inferior 285 
genio-hyo-glossus 247 
genio-hyoid 247 
gluteus maximus 284 
medius 285 
minimus 286 565 
Index. 
Muscle, or Muscles (Continued) : 
gracilis 290 
of hand 279 
of hip 284 
iliacus 291 
infraspinatus 262 
intercostal 257 
of larynx 219 
latissimus dorsi 252 
levator anguli scapulae 253 
longus colli 251 
masseter 313 
mylo-hyoid 247 
of neck 242 
obliquus abdominus externus 234 
internus 236 
obturator externus 287 
obturator, internus 286 
omo-hyoid 245 
of palate 171 
of pharynx 172 
pectineus 293 
pectoralis major 257 
minor 258 
of perineum 529 
peroneus brevis 301 
longus 301 
plantaris 297 
platysma myoides 243 
popliteus 297 
pronator quadratus 272 
radii teres 269 
psoas magnus 291 
pterygoid, external 315 
internal 315 
pyramidalis abdominis 238 
pyriformis 285 
quadratus femoris 286 566 
Index. 
Muscle, or Muscles (Continued) : 
lumborum 241 
rectus abdominis 237 
rectus capitis anticus major 250 
minor 251 
lateralis 251 
femoris 292 
rhomboid 253 
sartorius 289 
scalenus anticus 249 
posticus 250 
semimembranosus 288 
semitendinosus 288 
serratus magnus 259 
posticus, inferior 254 
superior 254 
soleus 296 
splenius 254 
sterno-cleido-mastoid 243 
sterno-hyoid 245 
sterno-thyroid 245 
stylo-hyoid 247 
stylo-pharyngeus 173 
subclavius 258 
subscapularis 261 
supinator brevis 277 
longus 274 
supraspinatus 262 
temporal 314 
teres major 263 
minor 262 
thyro-arytaenoideus 220 
thyro-hyoid 245 
tibialis anticus , 299 
posticus 298 
of tongue 168 
transversalis abdominis 237 
trapezius , 252 Index. 
567 
Muscle, or Muscles (Continued) : 
triceps extensor cubiti 266 
cruris 292 
vastus externus 292 
internus 292 
N. 
Nares, anterior 112 
posterior 112 
Nasal bones 92 
articulations of 117 
Neck, muscles of 242 
triangles of 248 
veins of 412 
Nerves, or Nerve 459 
anterior crural 482 
anterior interosseous 473 
auditory 510 
auricularis magnus 461 
chorda tympani 509 
ciliary 504 
circumflex 477 
cranial 497 
dental, anterior 505 
inferior 506 
posterior 505 
descendens noni 516 
dorsal spinal 477 
eighth pair 510 
eleventh pair 515 
external cutaneous 481 
facial 508 
fifth 502 
fourth 501 
frontal 503 
genito-crural 481 
glosso-pharyngeal 510 
gluteal, superior 486 568 
Index. 
Nerves, or Nerve (Continued) : 
great petrosal 509 
great sciatic 489 
gustatory 507 
hypoglossal 516 
ilio-hypogastric 480 
ilio-inguinal 480 
intercostal 477 
intercosto-humeral 469 
internal cutaneous 469 
lachrymal 503 
laryngeal, recurrent 514 
superior 513 
lesser sciatic 488 
long saphenous 483 
lumbar 478 
" plexus 479 
lumbo-sacral 484 
maxillary, inferior 505 
superior 504 
median 472 
middle cutaneous 482 
musculo-cutaneous (arm) 468 
(leg) 496 
musculo-spiral x 474 
ninth 510 
obturator 482 
occipital, small 461 
olfactory 499 
ophthalmic 502 
optic 500 
perineal 487 
phrenic 463 
plantar, external 493 
internal 493 
pneumogastric 512 
popliteal, external 494 
internal 490 Index. 
569 
Nerves, or Nerve (Continued) : 
posterior interosseous 476 
pudic, internal 486 
radial 475 
recurrent laryngeal 514 
sacral plexus 485 
saphenous, long 483 
short 492 
sciatic, great 489 
small 488 
sixth 507 
spinal, accessory 516 
splanchnic, great 521 
small 522 
subscapular 467 
superficialis colli 460 
suprascapular 465 
sympathetic 517 
tenth 512 
third 501 
thoracic, anterior 467 
posterior 466 
tibial, anterior 495 
posterior 492 
twelfth 515 
ulnar 470 
vagus 512 
O. 
Obturator artery 391 
externus muscle 287 
internus 286 
Occipital artery 324 
bone 69 
articulations of 113 
fossa .. . . 108 
Occipito-atlantal articulation 128 
Occipito-axial 129 570 
Index. 
(Esophagus 174 
Omentum, great 181 
lesser 181 
Orbit 109 
Orbit, arteries of 398 
muscles of 306 
nerves of 500-503 
Os calcis 59 
innominatum 43 
Ovary 213 
P. 
Palate bone 94 
articulations of 118 
hard ' 103 
muscles of 170 
Palmar arch, deep 352 
superficial 348 
Pancreas, relations of 188 
structure of 201 
Parietal bones 71 
articulations of 114 
Patella 53 
Pelvis 48 
Penis 208 
Perineum 128 
Peritoneum 178 
Pharynx 167 
Pleura 225 
Pouch of Douglas 212 
R. 
Radial artery 346 
hand and wrist 350 
nerve 475 
Radius . 32 Index. 
571 
Rectum, relations of, female 213 
male 186 
Renal artery 373 
Retina 551 
Ribs 18 
Ring, abdominal external 531 
internal 531 
femoral 535 
s. 
Sacral arteries 39 
foramina ; 14 
plexus 485 
Sacrum 13 
Scaleni muscles 249 
Scapula 23 
Scarpa's triangle 295 
Sciatic artery 392 
nerve, great 489 
lesser 488 
Shoulder joint 136 
Skull, anterior region 109 
base of, lower surface 103 
upper surface 106 
lateral region 101 
vertex 100 
Spermatic artery 372 
canal 532 
Sphenoid bone 79 
articulations of 115 
Spinal cord 455 
nerves 458 
Spine in general 15 
Splanchnic nerves ' 521 
Spleen, relations of 188 
structure of 201 
Sternum 17 572 
Index. 
Stomach, relations of 181 
structure of 192 
Subclavian artery, left 357 
right 329 
Sulci of brain 430 
Sympathetic nerves 517 
T. 
Testes 209 
Thorax 21 
Thyroid cartilage 215 
Tongue 168 
Trachea 224 
Trapezium bone 36 
Trapezoid " 37 
Triangle of Hesselbach 534 
Scarpa's 295 
U. 
Ulna 29 
Ulnar artery of forearm 347 
hand 348 
nerve 470? 
Ureter 204 
Urethra, female 214 
male 208 
Uterus 211 
V. 
Vagina 214 
Vas deferens 207 
Veins, or Vein 400 
axillary 412 
azygos 420 
basilic 411 Index. 
573 
cardiac 421 
cava, inferior 404 
superior 420 
cephalic 411 
femoral 402 
of Galen 413 
iliac, common 403 
external 403 
internal 404 
inferior cava 404 
innominata, left 419 
right 419 
jugular, anterior 418 
external 417 
internal 417 
popliteal 402 
portal 404 
saphenous, long 408 
short 407 
spermatic 406 
subclavian 412 
ulnar, anterior 409 
common 410 
posterior 409 
Ventricle of brain, third 442 
fourth 400 
lateral 392 
Vertebra, typical 7 
cervical 8 
dorsal 8 
lumbar 9 
Vertebrae, peculiar 10 
first cervical, or atlas 10 
second cervical, or axis 11 
prominens or seventh 13 
peculiar dorsal 13 
pelvic 13 
sacrum 13 574 
Index. 
coccyx 15 
Vertebral column 6 
Viscera 165 
coecum 183 
ascending colon 184 
sigmoid flexure 185 
rectum 186 
liver 186 
spleen 188 
pancreas 188 
kidneys 189 
bladder 190 
Vocal cords, true 221 
false 222 
W. 
Willis, circle of 400 
z. 
Zinn, ligament of 311