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Full text of "Descriptive anatomy"

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QM23 T65 1 898 Descriptive anatomy 



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DESCRIPTIVE ANATOMY 



WM. B. TOWLES, 



FORMER Professor of Anatomy in the University of Virginia 
AND IN THE University of Vermont. 



REVISED AND ENLARGED 

BY 

W. G. CHRISTIAN, 
present Professor of Anatomy in the University of Virginia. 



ANDKRSON BROS., PUBLISHERS, 

University of Virginia. 

1898. 



u 






COPYRIGHT, 
1898, 

BY 

ANDERSON BROS. 



i\VVE_P/?^V7. 







PREFACE. 

Towles' Notes on Anatomy, which forms the basis of the 
present work was not the work of a single man, but the out- 
growth of a school. This school, founded here, probably, by 
Prof. Robley Dunghson, who brought the Edinburgh tradi- 
tions into his teaching, was perfected by Prof. John Staige 
JJavis, who, in his turn, instructed Prof. Towles, from whom 
the present writer acquired what knowledge of anatomy he 
possesses The effort of all of the teachers in this school 
has been to make the instruction clear, simple, and practical ; 
and these have been the characteristics of the Notes While 
endeavoring to increase the amount of information contained 
m the work and to make it more representative of the lectures 
the writer has tried to preserve those characteristics which 
have alw^a3^s distinguished the School of Anatomy at the Uni- 
versity of Virginia. At this late day it is impossible for any 
one towrite an original work on such a subject as anatomy, 
and originality is not claimed for this work. It has simply 
been the writer's purpose to adopt the best, in his opinion 
trom all of the other writers he has been able to read ; but at 
the same time, no statement has been made in this book which 
has not been verfied by dissection. 

The effort has been made to make this a student's book • it 
IS not intended to imitate those works which are designed for 
practitioners and students alike. In the opinion of the writer 
a successful work of the kind last mentioned is a manifest 
impossibility, the needs of the student and the needs of the 
practitioner being entirely dissimilar. It has been the inten- 
tion in this work to give to the student a clear, complete state- 
ment of the positive truths of anatomy, leaving embrvology 
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 descriptive 
anatomy, pure and simple, in such a way as the needs ..f the 
student demand. 

Universily of Virgima. W. G. Christian. 

Aiig^ist, i8g8. 



DESCRIPTIVE ANATOMY. 



OSTEOLOGY. 

fj^- d'"^/ °n *' ^"'' '"^'"^ ^° '° f"^™ the human skele- 
ton md.vxdually and ,n relation to one another, with re<.ard 
to the appearaiices which they present to the unaided eve and 
he uses for wh.ch they are intended, constitutes Osteo o " 
as perta,n,n^ to Descriptive Anatomy. The chief uses of 

tissues. 2d. To form receptacles for important organs. 3d 
To form uny.eld.n^ points of attachment for the muscles: 

n!ayb?utni7ed.^^ ''''''' '''°'''' -''''' "--- -tion 
In order to fulfill these functions, bones present manydiffer- 

mto. 1st. Long Bones, when the extension in one direction 
Srreatly exceeds that in the other. 2d. Plat Bones, when he 
extension ,n two directions greatly e.xceeds that i^ the olher 

relation to other Jnes. 2d. Th^e^'cTass tf wl^ch^ ifb:!::^ 
3d. &,veadescr,pt,on of the appearances on the bone: whethe 
here be surfaces, borders, extremities, shaft, depressions or 
elevafons, and especially note any articular surface thalis a 

nect.on ,t ,s proper to explain two technicalities of frequent 
use -Internal and External-these terms should be used 
w.th reference to the middle line or plane of the body, that is 
ne object >s ,„ternal to another because it is nearer th' midd 
cav^'tv . ''• "" f "" "'"' '"-■-■•ectly with reference to a 

The' bo ^", T""' """^ '"' '^™^ '" "e here emoloyed. 

The bones are d,v,ded into those of the vertebral column o 
e Thorax: of the Upper Extremity: of the Lower Extremity 
of the skull; the Os Hyoides; the Ossicula Auditus 



DESCRIPTIVE ANATONY. 



The Vertebral Column. 



The vertebral column or spine, consists of a series of sep- 
arate bones, classed as irregular, called vertebra, and extends 
from the base of the skull to the lower termination of the 
TDelvis It is flexuous in direction and of unequal size at dit- 
ferent 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, 
o-ivino- support on each side to the bones which enclose the 
thoracic cavitv, 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 re- 
ceptacle for the spinal marrow and its envelopes. In the adult 
it consists of twenty-six pieces, called vertabras, which are 
divided into four classes; in the neck they are called cervical 
vertebrae, and are 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 vertebra of the different regions have 
characteristics which distinguish them from those of other 
reo-igns, and each vertebra certain less noticeable ones which 
designate its position in its own region. Kach region, how- 
ever, possesses one or more bones so widely different from 
the typical vertebra of that region as to deserve the appellation 
of "Peculiar." 

Since there are appearances common to the vertebrae ot all 
regions, these must be first noted. 

Vertebra. 

Kach vertebra consists of the following parts : 1st, Body ; 
2i, Foramen for the spinal cord;. 3d, Lamina (2); 4th, Pedicles 
(2)'; 5th, Spinous process ; 6th, Transverse Processes (2) ; 7th, 
Articular Processes (4); 8th, Intervertebral Notches (4). 



OSTEOLOGY. 3 

]st. The Body is the front, thick, massive portion of the 
bone, flattened above and below to articulate with adjoining- 
bones, indirectly by the intervention of cartilag-e ; it is more 
or less circular in outline and slig-htly flattened behind ; the 
edg-es 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. 

2d. The Spinal Foramen lies between the body in front and 
the spinous process behind, and is bounded laterally by the 
lamina. It is a large opening-, varying- in form and size in the 
different regions. 

3d. The Lamina spring-s, one each side, from the postero- 
lateral aspect of the body, throug^h the medium of the pedicle, 
and arches back to meet its fellow to form the spinous process 
thus inclosing the spinal foramen. It is flattened from side to 
side, and presents an upper and a lower border. 

4th. The pedicle is the more or less rounded commencement 
of the lamina. 

5th. The Spinous Process juts backward from the union 
of the two laminae. 

6th. The Transverse Process projects laterally from near 
the anterior extremity of the lamina on either side. 

7th. The Articular Processes are four, two superior and 
two inferior. They extend upward and downward from the 
lamina. 

8th. The Intervertebral Notches are four, two superior 
and two inferior ; they are furrows on the upper and lower 
aspects of the pedicles. 

Cervical Vertebra. 

The discrimination of a Cervical Vertebra involves the fol- 
lowing- points: it is the smallest; its body is smallest, having- 
its transverse diameter g-reater than the antero-posterior ; on 
its upper aspect the lateral edges are raised into ridg-es. The 
spinal foramen is larg-est and is triangfular. The lamina is 
narrow and long-. The spinous process is triang-ular and 
bifid at the extremity, g-enerally. The transverse process is 
perforated at its base by an opening- called the vertebral fora- 



4 DESCRIPTIVE ANATOMY. 

men, is grooved above and bifid at its extremity, forming- two 
nodules which are called the anterior and posterior tubercles of 
the transverse processes. The Articular processes are oblique ; 
the superior face upward, inward and backward, the inferior 
downward, forward and outward. 

Dorsal Vertebra. 

To discriminate a typical Dorsal Vertebra the following- 
appearances must be noted: 

The body is intermediate in size betw-een that of a cervical 
and a lumbar vertebra ; there is no g"reat preponderance of the 
one diameter over the other ; althoug-h in the upper part of the 
reg"ion the transverse is slig-htly g-reater, and in the middle 
portion the antero-posterior. 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 foramen is smaller than in the other re- 
g-ions, and is nearly round. The lamina is short, slopes 
obliquely from behind, upward and forward, and is almost 
entirely covered by the orig-in of the processes which spring- 
from it. The pedicle is deeply notched inferiorly. The 
spinous process is triang-ular, and is disting-uished from that 
of a cervical vertebra by not being- bifid, it extends downward 
and slig-htly backward. The transverse process is peculiarly 
well marked, being- large, long- and extending- outward and 
backw^ard, increasing- in size as it removes from its orig-in so 
as to present an enlarg-ement at its termination ; that is, it is 
"clubbed." It bears on its anterior face, near its termination, 
an articular facet. The superior articular processes are ver- 
tical and look from each other, outward and backward ; the 
inferior are opposite. 

A Lumbar Vertebra. 

In the lumbar reg-ion the whole bone is more massive than 
in the cervical and dorsal reg-ions. The body is larg-e, its 
transverse diameter g-reater than the antero-posterior. Its 
anterior surface is concave from above downward, convex from 



OSTEOLOGt". 5 

side to side, slightly lipped above and below. The superior 
and inferior faces present a concave central portion with an 
elevated circumference. The posterior face althoug-h nearly 
flat, presents a slig^ht concavity from above downward and 
from side to side with larg-e opening's 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 larg-e 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 laminae, short and massive, pass downward 
backward and inward to join the spinous process, and are 
partly hidden by processes. The spinous process is nearly 
quadrilateral, strong and thick. It projects straight back- 
ward and terminates in a blunt, rough almost clubbed extremity. 
The transverse processes spring from the junction of the body 
and pedicles. They are long narrow, thin and curved, resem- 
bling a rib in shape. They pass backward and outward with 
a slight inclination upward. The superior articular processes 
are cut nearly vertically, as in the dorsal region, but, unlike 
the latter, face toward each other so that their direction is 
backward and inward. They are concave from before back- 
ward 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 be- 
fore backward and face outward and forward so as to be 
received between the inverted 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 that region. Toward the con- 
fines of each region the vertebrae partake more or less of the 
characters of vertebrae 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 



6 DESCRIPTIVE ANATOMY. 

the typical vertebra is so g-reat 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 
weig-ht of the head ; it resembles only in a slig-ht deg-ree a ty- 
pical 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 fora- 
men of remarkable size — much larg-er than in any other verte- 
bra. 

The lateral masses stand one on each side, being- connected 
before and behind by the anterior and posterior arch. The 
anterior arch 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 anterior tubercle of the 
Atlas and opposite this, on the posterior face of the anterior 
arch, is a circular, concave articular facet for the o^Ojitpid 
process of the next vertebra. 

The ppsterior arch forms about two-fifths of the circumfer- 
ence of the bone. It is convex and rough behind, presenting 
in the mid line a slig-ht rough eminence called the posterior 
tubercle of the Atlas, a rudimentary spinous process. The upper 
bordler of the posterior arch presents, jjist 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 
typical vertebra. 

Kach lateral mass forms about one-fifth of the bony circle, 
and sustains, above and below, the articular processes. The 
superior are oval, concave, oblique, articular pits, whose long 
diameter is directed from in front backward and outward ap- 
proaching each other more nearly in front than behind, ^d 
looking upward, inward, and forward. About their middle 



OSTEOLOGY. 7 

they are frequenty slig-htly encroached upon by the non-articu- 
lar portion of the bone so as to g-ive them something- of a kid- 
ney shape. The inferior processes are smaller, circular, 
slightly concave or"Hat and directed downward, inwar3 and 
slightly backward. The inner face of each lateral mass is 
marked, just below the superior articular process, by a slight 
tu'Bercle intended for ligamentous attachment. The trans- 
yerse processes project outward and a little downward. They 
are large and prominent, perforated at the base but not 
marked by either groove or tubercle as in the typical vertebra. 

The Second Cervical Vertebra, or Axis. 

The body of the Atlas becomes ossified to the Axis and ap- 
pears on that bone as the odontoid process. This process occu- 
pies the whole of the upper surface of the Axis, springing by 
a slightly constricted portion called the neck, ascending* and 
enlarg-ing" for a short distance to again decrease and finally ter-^T' 
minate as a blunt point. On either side, just below the termi-^ 
nation, there is a rough depression for ligamentous attach- 
ment. Below this and on its anterior face, is a smooth circu- 
la'f, convex articular facet tcLplay oji a similar surface on the 
rfffteriof arch of the Atlas. Ju-st opposite to this, on the pos- 
terior surface, is a second smooth surface fgir the play of the 
transverse ligament. "T^he tjody is marked in front by a verti- 
cal ridge and on either side of this by deep depression. The 
superior articular facets appear to be seated on the junction of 
the pedicles and body. They are circular in form, nearly flat 
and face upward and outward, possibly slightly forward. 

The transervse processes, less prominent than those of the 
Atlas, are not bifid and pass downward and outward. The}'' 
are pierced by the vertebral foramen, which runs from below 
upward toward the superior articular facet and then turns ab- 
ruptly outward, forming nearly a right angle. The laminae 
are thick and strong- ; the spinous process, strong- and thick, 
projects straight backward, is deeply g-rooved on its under sur- 
face and frequently bifurcated at the extremity. There is 
barely a trace of a superior intervertebral notch, which, when 
present, lies behind the articular process. The lower portion 



8 DESCRIPTIVE ANATOMY. 

of the bone presents the characteristics of a typical cervical 
vertebra, but is more massive. 

Vertebra Prominens, or Seventh Cervical Vertebra. 

This vertebra derives its sobriquet of prominens from its 
possession of a remarkably long-, thick, uon bifid, spinous 
process, which disting-uishes it from the other cervical verte- 
brae. It is also larg-er 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 peculiar dorsal vetebrae are the first, ninth, tenth, 
eleventh and twelfth. 

The /i}'st presents on each side of its body, above andpostero- 
laterally, a whole facet for the head of a rib ; below, in 
corresponding position, a half facet on each side. The ninth 
has but one demi-facet on each side, which is on the upper 
border. The /^;z//^ 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 tzvelfth has one whole 
facet on each side ; its transverse process has no articular facet 
and its inferior articular processes are everted. 

The Pelvic Vertebrae. 

The pelvic vertebrae, specifically known as sacrum and 
coccyx, 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 (Sacer-Sacred.) 

The sacrum lies between the fifth lumbar vetebra above 
and the coccyx below, and between the two ossa innominata. 
It is triangular in outline, its base being- upward and its trun- 
cated apex below and backward and tipped by the coccyx. 
Its anterior face is concave, both from above downward and 
from side to side, more so in men than in women, this being- 
one means of disting-uishing- the sex to which the pelvis 



OSTEOLOGY. 9 

belonofed. It is described as consisting- of an anterior and 
posterior face, two lateral borders, a base and an apex. 

The anterior face 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 larg-er than the lower two. Con- 
necting- each foramen with the corresponding- one in the 
opposite row is a ridge ; these ridg-es marking- the line of 
union of the five separate vertebra? of which the sacrun con- 
sisted in the 3'oung- subject. Passing- outward from each 
foramen is a groove for a sacral nerve. 

The posterior face of the sacrum is narrower than the ante- 
rior, is convex both from above downward and from side to 
side and is rough. Above, in the mid line, is seen the trian- 
gular opening- of the spinal canal ; below this is a row of 
roug-h projections, the rudimentary spinous processes. The 
upper two of these are usually distinct, while tlje two lower 
coalesce. • The lower spine is wanting- and here the spinal 
canal is exposed. External to the sacral supines is seen a row 
of slig-ht projections, the rudimentary articular processes, 
and between these and the spines is a vertical g-roove, the 
sacral, continuous with the vertebral g-roove above. Exter- 
nal to the articular tubercles is a row of foramina, less reg-u- 
lar in outline and smaller in size than those on the front, the 
posterior sacral foramina, four in number like those on the 
anterior face. External to these again, and nearly on the 
lateral border, is another row of roug-h tubercles, the rudimen- 
tary transverse processes. 

The lateral borders, broad and thick above, narrow, thin 
and roug-h below, present superiorly and anteriorly a long-, 
ear-shaped 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 arti- 
culates. On either side of this is a broad, smooth expanded 
surface, called the wing of the sacrum. Behind the articular 



10 DESCRIPTIVE ANATOMY. 

surface is seen the triangular upper opening- into the sacral 
canal, a continuation 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 sacrum. On either side of the opening 
is an articular process. These processes, like the superior 
articular processes of a lumbar vertebra, face toward each 
other. In front of the articular processes on either side is a 
groove corresponding to the intervertebral notch of other ver- 
tebra. 

The apex, or lower extremity of the sacrum, presents an 
oval surface for articulation with the coccvx, and on either 
side of this an articular nodule, called the cornu. Behind the 
oval surface is the opening of the sacral canal which terminates 
the spinal canal. 

Coccyx. 

The coccyx forms the lower extremitv of the vertebral 
column; it originally consists of four pieces or verte- 
brae united, in the adult, into one bone, which is sometimes 
ossified to the sacrum. It is triangular in shape; its base is 
above, presenting an oval articular facet for the truncated apex 
of the sacrum; its apex is below and forward the bone con- 
tinuing the curve of the sacrum and frequently 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 vertebra from the second cervical to the last 
lumbar, the inferior consisting of the nine pelvic vertebra. 
On more careful examination it will be found that the supe- 
rior pyramid may itself be divided into three, one extending 
from the second cervical to the first dorsal, the second from 
the first to the fourth dorsal, base upward, and the last con- 
sisting of the remaining vertebra with the base at the fifth 
lumbar. These smaller pyramids are comparatively unimpor- 
tant. Although the general direction of the vertebral column 
is vertical, it does not present a straight line. In the cervical 



OSTEOLOGY. 11 

reg"ion, and including* the first and second dorsal vertebras, it 
is convex forward, in the dorsal concave forward, in the lumbar, 
convex and in the pelvic ag-ain concave forward. Thus it will 
be seen to consist of alternate compensatory antero-posterior 
curves, an increase in the curvature of one reg-ion always 
causing- a corresponding* compensation in the reg^ion below. 
Viewed from the front we see the convex bodies of the vertebrse, 
marked by their transverse g^rooves and separated by the 
intervertebral disks, the whole presenting- the curvatures above 
described. Posteriorly, in the mid line, will be seen the spi- 
nous 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 long-er 
in the dorsal region until the ninth is reached, but, owing- to 
their downward inclination, less prominent. Ag-ain prominent 
and projecting- backwards in the lumbar, they become indis- 
tinct in the upper sacral and disappear entirely in the lower 
sacral reg-ion. Sometimes there are normal deviations from 
the mid line even in health, so that the spines do not form a 
straig-ht line down the back. On either side of the spines is 
seen a g-roove 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 reg-ion. Laterally may 
be seen the sides of the bodies of the vertebrae, presenting- in 
the cervical reg-ion the transverse processes, g-rooved by the 
intervertebral foramina ; intervertebral foraminaand transverse 
processes with articular facets for ribs, in the dorsal ; and 
similar foramina and spine-like transverse processes in the 
lumbar reg-ion. The pelvic reg-ion 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-eig-ht inches long-. 

Sternum. 

The sternum or breast bone, forms the middle portion of 
the tho.racic wall in front, the dorsal vertebras occupying- the 



12 DESCRIPTIVE ANATOMY. 

mid-line behind; connecting* these on each side are the ribs, 
which are prolong-ed by the costal cartilages. Kxtending- out- 
ward 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 forward. Originally consisting of six parts, 
these in the adult become united into three — the upper or 
Manubrium, the middle, or Gladiolus, and the lower, E)nsi- 
form 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 posterior surface, upper and lower extrem- 
ity 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 side to side and smooth. The upper 
extremity is marked in the mid-line by a notch known as the 
inter-clavicular. E^xternal to this and located at the junction 
of the upper extremity and lateral border, is a smooth con- 
cavo-convex articular facet for the inner end of the clavicle. 
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 or second piece of the sternum, pre- 
sents an anterior surface, slightly convex from above 
downward and marked by three transverse ridges which 
indicate the junction of the four bones of which it was 
originally composed. The posterior surface is concave 
and smooth. The 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 



OSTEOLOGY. 13 

smaller facet for the Knsiform cartilag-e. The lateral borders 
are marked by a demifacet at the upper and lower ang-les re- 
spectively and four whole pits between these two. The upper 
demifacet is for the second costal cartilag-e, the lower, for 
the seventh and those between for the cartilag-es of the inter- 
vening" ribs. Between these pits are narrow, roug-h non- 
articular portions of bone. Occasionally the Gladiolus shows a 
foramen near its lower end. 

The E^asiform cartilag-e presents many varieties in shape 
and position. Above it has a small oval facet for the Gladio- 
lus, and on its lateral marg-in a half facet for the cartilag-e 
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 roug-h ante- 
riorly, concave and smooth posteriorly, larg-e and broad above, 
presenting- the articular facets for the clavicles and the inter- 
clavicular notch, narrow and pointed inferiorl}^ Laterally it 
is marked by pits for the reception of the cartilag-es of the 
seven true ribs. 

The Ribs. 

The ribs are twelve pairs of long- bones situated on the side 
and front of the chest and forming- the g-reater part of the bony 
wall of the thorax. They are known by numbers 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 individual, 
may be disting-uished, but not from different persons. 

A Typical Rib. 

A typical rib, being- a long- bone, has a shaft and two 
extremities. The posterior or vertebral extremity is some- 
times improperly called the head. It consists of a head, neck 
and tubercle. The posterior, or vertebral extremity has a 
head which presents two articular facets separated by an 
antero-posterior ridg-e. The facets look the one upward and 
backward, the other downward and backward, are oval in form 
and articular for the demi-facets found on the bodies of the 



14 DESCRIPTIVE ANATOMY. 

dorsal vertebrse above and below. The ridg-e is received in 
the interval between the two vertebra and is attached to the 
intervertebral disk. The neck extends outward and slig-htly 
backward from the head and terminates at the tubercle. It 
has an upper and a lower border, anterior and posterior sur- 
faces. The posterior surface is irreg-ular and roug-h for 
lio-amentous attachment; the anterior, smooth, concave, slopes 
obliquely from above downward and enters into the formation 
of the posterior wall of the thorax. The lower border is 
twice as thick as the upper, is long-er 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 
tubercle. In the lower ribs it rises from behind forward and 
terminates 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, slig-htly larg-er than the shaft and is surmounted 
bv a pit for the reception of the corresponding- costal cartilag-e. 

The shaft slopes obliquely from above downward and for- 
ward, the degree of obliquity varying with the different ribs. 
It presents two surfaces, internal and external, and two bor- 
ders, inferior and superior. The posterior part of the shaft 
is nearly round and extends from the tubercle to the ang-le of 
the rib. Its surfaces look forward and backward. Prom the 
angle the ribs slope and the surfaces become internal and ex- 
ternal. The external surface is convex from before backward, 
flat or slightly convex from above downward and is marked at 
the angle of the bone by an oblique ridge. The internal sur- 
face is concave from before backward, convex from above 
downward and smooth. Near the lower border is seen a long- 
g-roove which, starting near the angle 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 slig-htly roug-hened for muscular attachment. The in- 
ferior border, thin and sharp, overhangs the g-roove on the 
inner surface and is itself marked by the same g-roove near its 
anterior extremit}'. 




OSTEOLOGY. 15 

Peculiar Ribs. 

The peculiar ribs are the first, second, tenth, eleventh, and 
twelfth. 

The First Rib departs more widely from the t3'pical rib 
than any other. Its surfaces look one upward and forward, 
the other downward and backw^ard, its borders inward and 
outward. 

The superior surface, broad and fiat, presents near the 
middle an oblique ridg-e which separates two g^rooves, the in- 
ternal for the subclavian vein, the external for the subclavian 
artery. The external border, convex and roug-h and thicker 
than the internal border, is not marked by either ang-le or 
ridge as is the case with a typical rib. The posterior extrem- 
ity presents a head with only one articular facet, as this rib 
articulates with but one vertebra. The neck is flattened 
from above downward and has no crest. The anterior ex- 
tremity is thick and roug-h, being* marked on its upper sur- 
face by a roug-h elevation for the attachment of a lig-ament. 
The inferior surface is smooth. 

The second rib, long-er than the first, approaches 
more nearly the typical rib. It is marked by a crest on 
its neck and an ang-le and ridg-e on the shaft, but both 
are less distinct than in the typical rib. The tenth, 
eleventh, and twelfth each have a whole facet, articu- 
lating- 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 cartilag-e of the ninth and, throug-h it, to the seventh. 
The eleventh and twelfth are merely tipped at their extrem- 
ity with cartilag-e and are called floating- ribs, because they 
are not attached to any other rib. These ribs have no artic- 
ular facet on the tuberosity for the transverse process. 

The Costal Cartilages. 

The costal cartilag-es are flat pieces of hyaline cartilag-e 
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 superior and inferior. 



16 DESCRIPTIVE ANATOMY. 

They increase in leng"th from the first to the seventh and 
each has its separate pit on the sternum down to and includino- 
the seventh. From the seventh the cartilages are attached to 
the cartilag-e of the seventh rib and through it to the ster- 
num. 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 ob- 
liquely upward, the obliquity increasing from the fourth to 
the tenth, while the last two are horizontal or inclined 
slightly downward. 

The Clavicle. 

The Clavicle or, collar-bone, extends nearly horizon-- 
tally outward but 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 is thick, the bone grad- 
ually 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 back- 
ward. This surface is intended for articulation with a simi- 
lar saddle-shaped surface on the upper outer aspect of the first 
piece of the sternum. Generally, just below this, is found 
another articular facet to play upon the cartilage of the first 
rib. The outer extremity is flattened from above downward, 
rough and subcutaneous on its upper surface, slightly rough- 
ened on its lower surface, and presents at its tip a small articu- 
lar facet, oval in outline, the long diameter directed from be- 
fore backward, and looking downward and outward. This 
is for articulation with the the acromion process of the scapula. 
The body of the bone presents two surfaces, superior and 
inferior ; and two borders, anterior and posterior. 

The inferior surface presents a long shallow groove, the 
subclavian, terminated internally by the roughened surface 
which is sometimes a process and sometimes a depression, 
called the rhomboid impression. Following the groove 



OSTEOLOGY. 17 

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 roug-hened ridg-e, 
called the trapezoid ridg-c. The superior surface is round, 
convex, smooth except at its inner and outer ends, 
where it is roughened for muscular attachment, and is 
subcutaneous. The aulerior border is convex for its inner 
two-thirds, thick and round; concave for its outer one-third, 
thin and sharp. 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 bor- 
der, 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, 
situated on the upper postero-lateral aspect of the chest, 
extending" over the upper eig-ht ribs with the exception of the 
first. It consists of a body having- two surfaces and three 
borders, three angles and two processes. 

The anterior face, or venter, is concave, has ridg-es run- 
ning- 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 
is a smooth surface at the superior and inferior angles of the 
bone and along the posterior border, which while belonging- 
to the'venter of the scapula, does not belong- to the subscapular 
fossa. 

The posterior face, or dorsum, is convex from above 
downward, presenting- a prominent ridg-e, the spine, which 
commences at the posterior border and runs upward and out- 
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 triang-le being- directed outward, is concave from above 
downward and from before backward, and smooth. 



18 DESCRIPTIVE ANATOMY. 

The iufraspinous 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 triang-ular space at the 
inferior angle which do not belong to the infraspinous fossa, 
thoug^h 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 
bulg-e, and external to this a broad vertical g-roove. External 
to this groove is a prominent ridg-e which extends as far as the 
axillary border of the scapula. It is useless to say that the 
spine furnishes a portion of both supra and infraspinous fossse. 

The sj^ine is triang-ular and presents three borders, two 
of which are free, one looking- backward and the other outward 
and forward. The one which looks directly forward, 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 for- 
mation of the supraspinous fossa, and an inferior surface 
which is slig-htly convex from without inward, slightly concave 
from above downward, smooth, and forms part of the infra- 
spinous fossa. Its posterior border is roug-h, commences as a 
smooth triang-ular 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 acromion process. 

This posterior border presents a superior lip, an inferior 
lip, and an intermediate space intended for muscular attach- 
ments. 

The external border of the spine is smooth, round, and con- 
cave, and is the inner limit of the g-roove which extends around it 
and forms the means of communication between the supra and 
infraspinous fossae. The superior border of the scapula is 
thin, and is the shortest of the borders. Near its outer ex- 
tremity it is deeply notched, the notch being known as the 
suprascapular notch. 

It terminates in the superior ang-le of the bone by joining 
with the posterior or vertebral border. 



OSTEOLOGY. 19 

The posertior or vertebral border, commencing- at the supe- 
rior angle passes downward and inward to the point at which 
the spine spring-s from the posterior border. Prom this point 
downward it chang-es its direction, and is nearly vertical, with 
a slig-ht inclination outward. This border of the scapula, like 
the posterior border of the spine, is composed of two lips and 
a roug"h intervening* space. It is intermediate in thickness be- 
tween the superior and the axillary borders. 

The a?iterior, or axillary, or outer border is thick. Just be- 
low the external ang-leof the bone it presents a roug-h impress- 
ion from one-half to three-quarters of an inch in leng-th, which 
is intended for muscular attachment. Below this point is seen 
a vertical g-roove, which passing- downward upon the axillary 
border winds g-radually 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 ridg-e, 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 trans- 
verse 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 is situated at the 
junction of the superior and posterior borders, and is about a 
right angle. It is usually deflected slightly backward ; and 
presents anteriorly a smooth surface, belonging to the venter 
of the scapula, but not entering into the subscapular fossa. 

The inferior angle at the junction of the posterior and axil- 
lary borders is acute, having a roughened surface anteriorly 
and posteriorly. The anterior angle 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 hollow, 
oblong, vertical concavity, known as the glenoid cavity. 
This cavity has its long diameter directed from above 
downward. It is oval in outline, with the large end below 
and the small end above. It is supported upon the bone by 



20 DESCRIPTIVE ANATOMY. 

the narrow constricted portion, which is called the "neck" of 
the scapula. 

This neck is distinct anteriorly and posteriorly ; but above is 
obscured by the orig-in 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, which 
spring's from the bone just above the glenoid cavity. Its direc- 
tion is at first upward and slig^htly forward, but after pass- 
ing 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 back- 
ward and the other downward and forward ; but after the 
change in its direction one 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 back- 
ward, one which looks downward and forward, an external 
border, an internal border, and an apex. The superior sur- 
face 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 roug'h 
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 be- 
fore backward ; and the surface itself is oblique, looking* 
slightly upward and inward. The apex is roughened for 
muscular attachment. The upper surface of this process ap- 
pears to be a continuation of the posterior border of the spine, 
whose superior lip corresponds to the inner border of the 
process, the low^er 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 upper ex- 
tremity, is a long- bone having a shaft and two extremities. 



OSTEOLOGY. 21 

The Head, or Upper Extremity, presents for examina- 
tion a smooth, rounded portion the head proper, form- 
ing- something- less than half a sphere, which looks up- 
ward, inward and backward and is articular for the 
glenoid cavity of the Scapula. E^xternal to this is a 
constricted part of the bone, separating- the head from the 
next appearances, called the anatomical neck. It is narrow 
and well marked above but becomes indistinct below and be- 
hind. External to the anatomical neck there is a largfe projec- 
tion called the g^reater tuberosity. It is prominent and bulg-- 
ing, looks outward and forward and has on its summit three 
smooth impressions for the attachment of three of the muscles 
of the scapular g-roup. Internal to the greater is a smaller 
projection called the lesser tuberosity. It is sharper and 
more prominent than the greater tuberosity and has on its 
summit but one muscular impression. Between the two tuber- 
osities is a deep groove, the bicipital, bounded on either side 
by two prominent ridges, the internal and external bicipital 
ridges of the humerus. Below the tuberosities the bone is 
constricted and round, forming the surgical neck. 

The Louver Extremity is flattened from before backward, is 
bent forward, and presents a3light 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. Proceed- 
ing now from the external condyle inward, we next see a 
rounded articular surface, the eminentia capitata, whose 
articular surface extends higher up anteriorly than posteriorly. 
It is for articulation with the cup-like cavity on the upper ex- 
tremity 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 antero-posterior articular 
ridges, separated by an antero-posterior articular groove the 
three forming a trochlear surface for the reception of the 
greater Sigmoid cavity of the Ulna. The internal ridge is 



22 DESCRIPTIVE ANATOMY. 

larger and its articular surface extends higher up in front 
than the external. Above the trochlea, both before and be- 
hind, is a deep pit-like depression. The one in front is for 
the reception of the coronoid process of the Ulna, the one be- 
hind 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 fora- 
men between the two fossae. Between the inner condyle 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 
middle and below, presents three surfaces and three borders. 
The borders are anterior and two lateral; the surfaces, poste- 
rior 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 termi- 
ate 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 back- 
ward, then vertically downward to terminate as the internal 
condyloid ridge. It is prominent above and below, less dis- 
tinct in the middle of its course. The external border com- 
mences at the back of the greater tuberosity and passes straight 
down to the outer condyle where it becomes the external condy- 
loid ridge. "Very sharp and prominent below, rough and well 
marked above, it is obliterated in the middle by the passage of 
the musculo-spiral 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 mid- 
dle and smooth and looking forward and inward below. This 
surface is usually marked about its middle by the nutrient 
foramen, though this appearance is often found on the inner 
border. 

The external surface begins at the base of the greater 
tuberosity, passes straight downward to the middle of the 



OSTEOLOGY. 23 

bone and then curves forward until it is almost anterior. 
About the middle of this surface there is a larg-e roug-h surface, 
with the apex downward, called the deltoid impression from 
its supposed resemblance to the Greek "Delta" inverted. Be- 
low 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, obliter- 
ates 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 fore-arm. 

The Upper Extremity is composed of two processes called 
olecranon and coronoid. The olecranon process is found oc- 
cupying the summit of the bone and may itself be divided for 
study into a superior, posterior and anterior surface and two 
lateral borders. The upper surface, indistinctly quadrilateral 
in outline, terminates anteriorly 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 subcutaneous. The anterior sur- 
face is concave from above downward, convex from side to 
side, articular and enters into the formation of the greater 
sigmoid cavity. 

The Coronoid process juts forward from the front of the 
bone. It is triangular in form, the base of the triangle being 
attached to the bone while the apex points forward. It pre- 
sents a superior and an inferior surface and two lateral margins. 
The superior surface is smooth and articular, convex from 



24 DESCRIPTIVE ANATOMY. 

side to side, concave from before backward, and is continuous 
with tHe similar surface on the olecranon process. The infe- 
rior surface is very irregular. It is marked near its middle 
by a rough impression 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 junc- 
tion 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. 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 articular 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 Lozver Extrejnity of the ulna is much smaller than the 
upper, and consists of two projections separated by a 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 th.e. styloid ■p7'ocess of the ulna. The outer process is 
called the capitiiliim 2el?2ce(Dim.. of Latin caf>i{t, head) and is 
artfcular 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- 
cartilage 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 circumfer- 
ence is smooth and convex, and intended to play in the cavity 
which is found upon the lower extremity of the radius. 

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, 



OSTEOLOGY. 25 

posterior and external, or interosseous. The anterior surface 
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 inter- 
nal surface is broadband flattened above, convex and slightly 
flattened in the middle, round and narrow below. The poste- 
rior surface is widest about its middle and presents usually a 
vertical ridge, which divides it into two unequal portions, of 
which the inner part is the broader. The upper portion of 
this surface presents a small triang'ular space ; below it is 
rounded like the remaining surfaces. Of the borders, the 
anterior begins above at the inner side of the base of the coro- 
noid 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 
posteterior border commences above at the apex of the triangle 
of the posterior surface of the oelcranon process. Prominent, 
well-marked, and sub-cutaneous above, it becomes round and 
smooth below, and terminates at the back of the styloid pro- 
cess. The external or interosseous border commences 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 indistinct 
or imperceptible, and terminates at the front of the capitulum 
ulnai. 

The Radius. 

The Radius (L. radius, a ray, or spoke of a wheel) is the 
outer of the two bones of the fore-arm ; and like other long 
bones it is divided into a shaft and two extremities. 

Its Ufiper 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 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 tuber- 
cle or bicipital tuberosity of the radius. This tuberosity 



26 DESCRIPTIVE ANATONY. 

presents posteriorly a prominent roug-h elevation, for mus- 
cular attachment while anteriorly it has a smooth surface 
for the play of a bursa. 

On the large Lozuer Extrejuity we find the summit present- 
ing- 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 is divided into two 
portions by a slig"ht 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 triang*ular in form. 
The internal portion, quadrilateral in form, is continuous with 
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 sig'moid cavity of the 
radius. Between these two, the sigmoid and carpal cavities, 
is found a non-articular strip, intended for the attachment 
of the fibro-cartilage. The anterior face of the lower ex- 
tremity is roug-h, 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, while of the 
remaining three, one, very narrow, is separated from the 
styloid process, b}'' a very prominent projection of the bone, 
while the other is broad and shallow, and is found near the 
inner end of the posterior face. 

The Styloid Process itself presents an internal and an exter- 
nal face : the internal being articular, and continuous with the 

8 articular surface of the carpal cavity ; the external rough for 
ligamentous attachment, and marked by the grooves above 
mentioned. Its anterior and posterior borders are roughened, 
while its tip has a blunt point. 

The Shaft of the radius has three surfaces and three bor- 
ders. The surfaces are anterior, posterior, and external ; 
the borders anterior, posterior, and internal or interosseous. 
The anterior face is narrow above, slightly convex, becomes 



OSTEOLOGY. 27 

broader as It approaches the lower extremity of the bone, 
is slig-htly concave in the middle and is flat at the lower 
end. It is marked b}^ an oblique ridg-e, which will 
be mentioned later. The -posterior face is convex in the 
upper and lower portions of its course, slightly concave 
in the middle. The external face is convex throughout 
its extent, so that the bone appears to be bowed outward. 
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 situation 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 beg"ins 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 sty- 
loid process. The internal border or interosseous ridg-e, 
beg-ins also at the tuberosity near its posterior portion, passes 
downward, sharp and prominent about its middle, more indis- 
tinct below, and terminates at the lower extremity of the 
bone, by dividing- into two lines which enclose the sigmoid 
cavity of the radius. 

The Hand. 

The skeleton of the hand consists of the skeleton of the 
Carpus, 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: 1st, the Scaphoid; 2nd, the 
Semilnnar ; 3d, the Cuneiform, on the front of which plays a 
sesamoid bone, called the Pisiform. In the lower row in the 
same order are : 1st, the Tra-pcziiim ; 2nd, the Trapezoid \ 3d, 
the Os Magnum ; 4th, the Unciform. 

The Bones of the Upper Row. 

The bones of the upper row articulate laterally with one 



28 DESCRIPTIVE ANATOMY. 

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 cueniform ; 
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. This bone has a su-perior surface, which is 
rounded, convex, and articular for lower end of Radius; an 
inferior surface, which is concave and articular for the upper 
extremity of the os magnum; an outer 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 
articulation with a similar facet upon the semilunar. Ivike all 
the bones of the carpus, the anterior and posterior surfaces are 
non-articular; but unlike most carpal bones, the anterior sur- 
face is broader than the posterior. 

The Semilunar, the second bone in the first row, has a superior 
sinface, convex, 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 mag-num,the other long* and narrow for the unci- 
form; an outer edg-e, articular for the scaphoid; and an inner ^ 
triang-ular in shape, larg-er in size than the outer one, and ar- 
ticular for the cuneiform; anterior and f>osterior surfaces, 
roug-hened and non-articular. The anterior surface is broader 
than the posterior, as is the case with the scaphoid. 

The Cuneiform presents an inferior surface, concavo- 
convex for articulation with the unciform; an external sur- 
face, flat, slightly triang-ular, articular for the semilunar ; 
an antero-external surface, which is articular for the pisiform, 
while internally it terminates in a blunt projection which is 
not articular. Tho. postei'ior surface is broad and roug-h, the 
anterior surface is rough and narrow. It is usually said that 



OSTEOLOGY. 29 

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 slig-htly outward. 

The Pisiform 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 g-enerally de- 
scribed as being- the only bone of the carpus which is articular 
upon its posterior surface. 

The Bones of the Lower Row. 

The Trapezium, the first bone of the second row, is easily 
disting-uished by the possession of a concavo-convex, or saddle- 
shaped articular surface, which is directed downward and 
outward. This is its inferior surface. Its superior surface 
is marked by a smooth, concave articular surface for the re- 
ception of the outer end of the scaphoid. The outer surface 
is roug-h, prominent and non-articnlar. The inner face is 
marked above by a smooth concave articular surface for the 
outer face of the trapezoid, while below this, separated from 
it by a rough groove, is a flat surface, looking- downward and 
inward for the second metacarpal. Its f>osterior surface, 
broader than its anterior, is roug-h and prominent, while the 
anterior surface is easily disting-uished by an oblique g-roove, 
which runs from above downward and inward. 

The Trapezoid can be most easily disting-uished by exclusion, 
having- none of the characteristics of the other bones. It has 
a broad, somewhat quadrilateral posterior surface ; a narrow 
and roug-hened aiiterior surface. Its superior surface is con- 
cave, and articular for the held of the scaphoid. Its external 
surface is slig-htly convex above for articulation with the trape- 
zium. The inferior surface is concave from before backward, 
and articular for the head of the second metacarpal bone; while 
the internal surface is also concave from before backward, and 
articular for the lateral aspect of the os magnum. 

The Os Magnum 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 



30 DESCRIPTIVE ANATOMY. 

further on its posterior than on its anterior aspect. Inferiorly 
it presents a quadrilateral, oblique articular facet, which artic- 
ulates 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 edg-e of the 
upper extremity of the second metacarpal bone. The outer 
surface presents an articular facet, at the anterior infe- 
rior angle, convex from before backward, for articulation with 
the inner face of the trapezoid. The internal surface presents 
near its posterior marg-in 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 
anterior face ^ narrower, than the posterior, is bulging and 
prominent, and roughened for ligamentous attachment. 

The Unciform is more easily distinguished than any bone 
of the hand. Its upper face looks upward and inward; and 
is frequently described as its internal face. This face is in- 
tended for articulation with the cuneiform ; and presents like 
that bone a concavo-convex articular surface, which is contin- 
uous with the upper extremity of the bone, also convex for 
articulation with the os magnum. Its outer face looks outward 
and slightly downward ; and is marked near the posterior 
surface by an Iv-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 articu- 
lar facets, separated by a slight ridge, these facets articulating 
with the fourth and fifth metacarpal bones. Its posterior face, 
much broader than the anterior, is roughened for ligamentous 
attachment. ^\i^ 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 p7'ocess, 
looks forward and slightly outward, being a little curved in 
its course. It is one of the prominent land-marks of the hand. 
The remainder of the anterior face is roughened for ligamentous 
attachment. 



OSTEOLOGY. 31 

The Carpus as a xcholc presents us with four separate sets 
of articulations ; vi2. The articulation betxveen the upper rozu 
of the carpus and the zurist, the articulation between the first 
and second rows, the articulation between the second row and the 
metacarpal bones, and the articulations between the individual 
bones of the carpus. When examined in the articulated skel- 
eton, 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, the semilunar, and the cuneiform, the 
pisiform not entering- into its formation. The articulation 
Ijctzjeoi the tzuo 7'ozus of carpal bo)ies is sinuous in outline, or 
concavo-convex, the trapezium and trapezoid tog-ether forming- 
a cavity for the reception of the head of the scaphoid, while 
the head of the os mag-num and the upper end of the unciform 
form tog-ether a convex articular surface received into a con- 
cavity which is contributed to by the scaphoid, the semilunar, 
and the cuneiform bones. The articulation betzveen the bo?ies 
of the second roz'j and the metacarpal bones consists first of a 
saddle-shaped articulation, the trapezo-metacarpal ; while the 
remaining- articulations vary in form with the varying- surfaces 
found upon the extremities of the metacarpal bones and the 
corresponding- surfaces on the carpal. TJie articulations be- 
izveen 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, thoug-h it is said that the cuneiform is articular ante- 
riorly and the pisiform posteriorly, 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 directed to the front, and whose 
convexitv 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 posterior than upon their 
anterior aspect. This arch of course g-ives streng-th to the 
hand, while at the same time permitting the necessary flexibility. 



32 DESCRIPTIVE ANATOMY. 

Metacarpus. 

The metacarpus is formed by five bones classed as long- 
bones ; four of these, for the four fiug-ers, being- nearly paral- 
lel, 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 they do not articulate with one 
another. The metacarpus, like the carpus, is arched trans- 
versely, the convexity being posterior. One of its constitu- 
ents 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 is quadri- 
lateral ; and it presents anterior and posterior surfaces, of 
which the posterior surface is the broader, these two surfaces 
being- roughened for ligamentous attachment; two lateral 
surfaces, which are marked by articular facets, intended for 
articulation with the adjoining metacarpal bones. 

The Summit of the bone is marked by a quadrilateral 
articular facet, for articulation with one of the carpal bones 
of the second row. 

The Lozver Extremity, 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 depres- 
sion, 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 passag-e 
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 Ion- 



OSTEOLOGY. 33 

g-itudimal ridgfe, with a slig-ht depression upon either side 
of it. This ridg-e, as it passes downward, divides about 
the middle of the bone into two, each, graduall}'- sepa- 
ratinor, descends to reach the tubercle above the lateral de- 
pression on the lower extremity. The triang-ular space 
between these diverg-ing- ridg-es is flattened. The lateral 
faces are concave and smooth from above downward, so that 
each pair of bones would leave between them a space for the 
attachment of muscles. These are known as the interosseous 
spaces. The bone is concave towards its anterior aspect, and 
marked by the anterior border, which is a rather indistinct 
vertical ridg^e separating" the lateral faces from one another. 

This description applies more or less closely to all the 
metacarpal bones; but each possesses appearances character- 
istic of itsell, by which it may be discriminated. E^ach bone 
is known by the name of the fing"er which it supports; but the 
metacarpal bones are also known by numbers from without 
inward. 

The Metacarpal Bone of the Thumb is the shortest and 
larg"est. Its posterior surface is broader and flatter than the 
remaining- bones, and its lateral borders are more distinctly 
marked w^hile upon its summit it bears a saddle-shaped or 
concavo-convex articular surface, concave from before back- 
ward, and convex from side to side. This with the absence 
of any lateral articular facet will disting-uish it from the other 
bones of the metacarpus. 

The Metacarpal Bone of the Index Fing-er is the long-est, 
is next in size to that of the thumb, while its base presents 
three articular facets, two of which are upon the summit, one 
flattened for articulation with the trapezium, one concave for 
articulation with the trapezoid, and one upon the internal 
lateral aspect for articulation wnth the metacarpal bone of the 
second fing^er. 

The Metacarpal Bone of the Second Finger 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 

Des Anat — 3 



34 DESCRIPTIVE ANATOMY. 

aspect an articular facet for the metacarpal bone of the ring- 
fing-er, while its upper outer posterior aspect is prolong-ed 
into a styloid process, projecting- upward between the trape- 
zoid and the os mag-num. On its inner lateral aspect the 
articular facet is divided into two by a g-roove. 

The Metacarpal Bone of the Ring- Finger, next in size and 
length, is the typical metacarpal bone. On its external lateral 
aspect a groove divides the articular facet into two for the 
two corresponding- facets on the inner lateral aspect of the 
metacarpal bone of the middle fing-er. 

The Metacarpal Bone of the Little Fing-er is the smallest. 
Its base presents a superior articular facet for the unciform, 
and a lateral facet on its outer aspect for the corresponding- 
facet on the metacarpal bone of the middle fing-er. On the 
inside of the base is a rough and prominent tuberosity with no 
lateral articular facet, which in itself disting-uishes it from the 
other metacarpal bones. 

The Phalanges. 

The Phalang-es 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 phalang-es, the second phalanx 
taking- the place of the characteristic ung-ual or third. 

The first phalanx is the long-er, and its shaft is semi-cylin- 
drical. The posterior surface is convex both from above down- 
ward and from side to side and is smooth. The ante- 
rior surface 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 shallow articular facet, whose transverse diameter is 
slig-htly g-reater than the antero-posterior, and it is almost cup- 
shaped. This is for articulation with the head of the meta- 
carpal bone. The Head or Lozuer Extremity presents an 
antero-posterior g-roove, surmounted on either side by an artic- 



OSTEOLOGY. 35 

ular ridg-e, constituting- a trochlear surface. On either side of 
the head is a slig-ht depression, marked in front and behind by- 
trifling' elevations or tubercles. 

The second phalanx presents on its base a receiving- surface 
for the trochlea ; that is, a central ridg-e 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 third, or ung-ual phalanx. The second phalanx with the 
exception of the head is like the first, only it is shorter and 
less massive. 

The Third, or Ung-ual Phalanx (Z. Ung-nis, a nail) presents 
on its base an articular surface to receive the trochlea of the 
second. It then becomes rapidly narrow ; but just before it 
terminates, it expands into a broadened surface. The bone is 
smooth on its posterior, but roug-h, prominent and flat on 
its anterior surface. The posterior aspect of this phalanx 
supports the nail, while the anterior surface supports the tis- 
sues which form the pulp of the corresponding- fing-ers. 
There being- but two phalang-eal bones for the thumb, the 
second phalanx for the thumb corresponds to the ung-ual 
phalanx for the other fing-ers. 

The Skeleton of the Lower Extremity. 

The skeleton of the lower extremity consists of the skeleton 
of the hip, thig-h, leg- and foot. 

Os Innominatum. 

The Os Innominatum (L. Theun-named bone) haunch bone, 
is the most important bone in forming- the pelvic cavity, and 
corresponds 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 irreg-ular in outline, this division 
has been retained in describing- the bone in the adult. 

The Ilium (Deriv. uncertain) or flank bone, is the larg-e, 
expanded, upper j)ortion of the bone. It is divided for study 
into and internal and external surface, anterior, posterior, 
and superior borders, the latter being- known as the crest. 



36 DESCRIPTIVE ANATOMY. 

The crest of the ilium is sinuous in outline. Viewed from 
in front it is seen to be convex for its anterior four fifths, con- 
cave for its posterior one fifth. In front and behind it termin- 
ates in roug^h projections, known as the anterior and posterior 
superior spinous processes. The crest consists of two lips, 
external and internal, and a roug-h intervening- space or middle 
lip. The anterior border consists of two projections, anterior 
superior 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 slig^ht g^roove separating* it 
from the margin of the acetabulum. The posterior border is 
less reg-ular 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 inferior spinous processes. 
They are sharper and less distinctly marked 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 g"reater sacro-sciatic. 

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 g-reat sciatic, and 
commencing- in this notch, and curving- forward and upward 
from it, are three lines disting-uished as superior, inferior and 
middle. The superior curved line, the shortest and most 
distinct of the three, beg-ins near the upper marg-in of the 
sciatic notch and passes upward and slig-htly forward until it 
reaches the crest near its posterior one filth. The middle, which 
is the long-est, beg-ins at the middle of the sciatic notch and 
passes upward and forward, markedly curved, to terminate 
just above the anterior superior spinous process. The inferior, 
the least distinct, starts at the lower portion of the notch and, 
passing- forward and slig-htly upward, reaches the anterior 
border of the bone a little above the anterior inferior spinous 
process. The whole surface is roug-hened for the attachment 
of muscles and presents the orifices of numerous foramina for 
the transmission of blood vessels, the larg-estof which is found 
near the middle of the bone just below the middle curved line. 



OSTEOIvOGY. 37 

The internal surface, much smoother than the external, is 
concave for its anterior two thirds both from above downward 
and from before backward, forming* the iliac fossa. Just be- 
fore the bone unites with the ischium it is crossed by a smooth, 
elevated ridge which forms a part of the ilio-pectineal line. 
The portion of bone below this is smooth, nearly flat, continu- 
ous with the inclined plane of the ischium, and enters into the 
formation of the true pelvis. The posterior one third of the 
internal surface is very irregular in outline. In front this sur- 
face is occupied by a roug-h, ear shaped articular surface which 
articulates with a similar surface on the sacrum. Behind this 
is a roug-h surface, made up of intervening- elevations and 
depressions for the attachment of lig-amentous fibres. 

The Ischium is the lower, massive portion of the bone. It 
is divided for study into a body, tuberosity and ramus. The 
body is triang-ular and presents for examination three surfaces 
and three borders. The surfaces are internal, external and 
posterior; the borders, anterior, posterior and external. Nearly 
the whole of the external surface is occupied by the articular 
surface furnished by the ischium to the acetabulum; but a small 
portion below the rim of the acetabulum is occupied by a 
g-roove, 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 roug-hened for muscular attachment. The anterior border 
is thin and sharp, slopes upward and forward to join the pubes 
and forms the posterior boundary of the thyroid foramen. 
The external border is thick and rounded and forms the 
posterior part of the rim of the acetabulum. The posterior 
border is long- and sharp, nearl}' 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 formation of the 



38 DESCRIPTIVE ANATOMY. 

great sacro-sciatic notch; below the spine, a similar, but 
shallower notch forms the lesser sacro-sciatic notch. 

The tuberosity is the rough lower end of the bone on ^vhicli 
the body rests w-'hen in the sitting- posture. It has an inferior 
surface w^hich is roug-h and triang-ular, and just above this, a 
smooth portion, divided into two bv an oblique ridge, the parts 
above and below the ridge being intended for muscular 
attachment. Internally it presents a rough, prominent ridge 
which separates the lower surface from the internal, and 
above this ridge a smooth g-roove. 

The Ramus passes forward, inw^ard and slightly up- 
ward. One surface looks outward and forward, the other 
inward and backward. One border looks outw^ard and 
forms the anterior boundary 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 inter- 
vening space. The two lips pass downw^ard to become con- 
tinuous with similar lips on the lower surface of the tuberos- 
ity. The internal border is averted, its upper part looking 
nearl}" 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 iL. Pubes, hair, or down) is divided for 
stud}^ into a body and a ramus. The body is the horizontal 
portion of the bone, and is divided into two surfaces, anterior 
and posterior, two borders, upper and lower, and tw^o extremi- 
ties, internal and external. 

The posterior surface is concave from before backward, 
convex from above downward and smooth. The anterior 
surface is convex from before backward, slightly concave 
from above downward, broad at its inner and narrow at its 
outer extremity, and rough for muscular attachments. The 
superior border is marked at its junction with the internal 
extremity by the angle of the pubis; external to this and run- 
ning outward and forward is a rough ridge called the crest. 
The crest terminates after a course of about three fourths of 
an inch in a prominent projection of bone called the spine. 



OSTEOLOGY. 39 

Runningf outward and backward from the spine and separating- 
the superior border from the posterior surface, is a sharp 
ridg-e of bone called the pectineal line; in front of which is a 
triang"ular surface, limited in front by the anterior surface of 
the pubis, the pectineal triang-le. The base of the triangle, 
which is directed outward, terminates in a rough prominence 
known as the pectineal eminence. The inferior border forms 
the superior boundary of the thyroid foramen and is marked 
by an oblique g-roove, which, from within the pelvis, extends 
forward and inward. The internal extremity, called the 
symphysis pubis, is an oval, roug^h articular surface, the long- 
diameter of which is directed from above downward and back- 
ward. It is covered by a series of nipple shaped projections 
and in the recent state is lined with cartilag-e. 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 for- 
ward, 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. a vessel for holding- vinegar, from a 
supposed resemblance) 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-iifths 
by the ischium. It is articular around the whole of its cir- 
cumference except a small portion at the lower and inner part, 
where a deep notch interrupts the prominent rim which else- 
where surrounds the cavity. This notch, called the cotyloid, 
leads to a deep non-articular depression in the bottom of the 
cavity, which in the recent state lodg-es amass of fat and, with 
its margins, g-ives attachment to the ligamentum teres. 

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 bv the outer border 
of the ischilo-pubic rami, above by the lower border of the body 



40 DliSCRIPTlVE ANATOMY. 

of the pubes, the groove on that bone furnishing- nearly the 
whole of the upper boundary. 

Pelvis. 

The Pelvis (L. a basin or laver, from a resemblance to an 
ancient basin.) The pelvic g"irdle is far more powerful than 
the shoulder g-irdle, the individual bones being more massive 
and bound more firmly to one another. The cavity has been 
divided by the ilio-pectineal line, into the true and the false 
pelvis, thoug-h the latter term should not be used, since the 
false pelvis is simply a part of the abdominal cavity. 

The pelvis is the cavity circumscribed by the sacrum, coc- 
cyx and two ossa innominata, containing- in the living- subject 
some of the small intestine, a part of the larg-e intestine, and 
the genito urinary apparatus, in part. It is bounded behind 
by the sacrum and coccyx and throug-hout the rest of its ex- 
tent by the ossa innominata. It is divided into two portions, 
the false pelvis and the true. The false pelvis is that por- 
tion between the two iliac fossae bounded behind by the 
junction of 5th lumbar and sacrum, while in front it 
has no bony wall. It extends from the crest of the ilium 
above to the pectineal line below. This pectineal line, 
also called linea ilio-pectinea, is a prominent ridg-e extend- 
ing 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 beg-ins. 
The plane circumscribed by the ilio-pectineal line is called, 
the brim or inlet of the pelvis, or superior strait of the pelvis. 
The true pelvis thus extends from this brim downward to 
what is called the outlet, or inferior strait of the pelvis. The 
outlet is limited in front by the lower end of the symphysis 
pubis; the arch formed by the diverg-ence of the pubic rami 
being called the pubic, or sub-pupic 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 render the plane of the inlet oblique, 
from behind downward and forward, and so g-reat is this obli- 
quity that the top of the symphysis pubis is about four inches 



OSTEOLOGY. 41 

below the level of the promontory of the sacrum. The so- 
called axis of the superior strait is an imag-inary line, perpen- 
dicular 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, latterally three and one-half inches, 
and at the pubes one and one-half inches. Besides these meas- 
urements, obstetricians employ others, as of the outlet and 
inlet, called diameters. The diameters usually g-iven are for 
the inlet, antero-posterior and transverse. 

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 g-reater 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 triang-ular; 2d, the pelvis is more capacious — meas- 
uring" more transversely and antero-posteriorly, but less ver- 
tically; 3d, the ang-le of the pubic arch is g-reater by 10°, 
measuring- from90° to 100°. 

The pelvis in the neg-ro is observably smaller than in the 
Caucasian. 

The Femur. 

The Femur (Z. Femur, the thig-h) is the long-est and most 
powerful bone in the body. It is divided for study into a 
shaft and two extremities. The upper extremity presents a 
head, neck and two tuberosities called trochanters. 

The Upper Extremily consists of the head, neck and two 
trochanters. 

The Head, smooth and g-lobular, projects upward, 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 which in the recent state lodg-es the outer end of 
the lig-imentum teres. The neck slopes downward, outward 
and backward from the head, is flattened from before back- 
ward and is divided into an anterior, and posterior surf ice, an 



42 DESCRIPTIVE ANATONY. 

Upper and a lower border. The anterior surface is flat and 
slightly roughened ; the ^posterior, convex from above down- 
ward, concave from within outward, 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. B2I0W 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 di- 
agonal, running from the postero-superior angle to the antero- 
inferior angle. The surface in front of the diagonal is rough, 
that behind 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 pro- 
jection which overhangs the digital pit. The lesser trochan- 
ter is much smaller than the greater, projects from the inner 
posterior aspect of the bone, is round in form, bluntly pointed 
at its apax and marked by a single muscular impression for 
the attachment of the biceps flexor femoris. Extending from the 
base of the great trochanter downward and inward to the lesser is 
a roughened ridge of bone known as the posterior inter-trochan- 
teric line. On the anterior aspect, and starting from the base 
of the great trochanter, there is a more prominent line which 
winds around the bone, pissing downward 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 Lozuer Extremity of the femur is flattened from before 
backward, so that the lateral diameter exceeds the antero- 
posterior. 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 



OSTEOLOGY. 43 

held vertically it will be seen that the inner condyle is pro- 
lonored downward considerably below the outer to compensate 
for the obliquity of the bone caused by the width of the pelvis, 
which separates the heads of v the bone, while the lower 
extremities approach each other. The long- diameter of the 
articular surface of each condyle is from before backward ; 
but it will be seen upon careful examination that the inner 
condyle is long-er and narrower than the outer, that its 
articular surface extends hig-her up behind and not so hig-h 
in front. The outer condyle is more oval, is shorter than 
the inner, its articular surface extending- hig-her up in front 
than behind. The two condvles are separated behind by a 
deep and roug-hened notch, called the intercondyloid notch. 
This notch is marked on either side by a depression for the 
attachment of the corresponding crucial lig^aments of the knee- 
joint. In front this notch is continuous with a smooth articu- 
lar surface, concave from side to side, convex from above 
downward, and forms a trochlea for the opposite surface of the 
patella. Each condyle presents an internal and an external 
surface. The external surface of the external condyle is 
marked by a prominent roug-h tuberosity, called the outer 
tuberosity of the femur; and below this is an antero-posterior 
g"roove for muscular attachments. The internal surface of 
the external condyle is the outer boundary of the intercondy- 
loid notch. The internal surface Q>i the internal condyle is 
likewise marked by a roug-h projection, called the internal 
tuberosity oj the femur; while the outer surface of the inter- 
nal 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 slig^ht depression on the posterior aspect 
of the bone, which is intended for the attachment of the g"as- 
trocnemius muscle. Leading- upward from either condyle is a 
ridge. These ridg-es approach each other above to reach the 
linea aspera. They are known as the condyloid ridges, and 
more properly belong- to the shaft of the bone. Between these 
ridg-es is a triangular roughened space called the Popliteal 
Triangle. 



44 DESCRIPTIVE ANATOMY. 

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 down- 
w^ard, 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 slig-htly concave fromabove downward, and smooth; 
the inter)ial 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, indistinctlv marked, 
down to the outer tuberosity of the femur. The internal lateral^ 
commencing- at the spiral line of the femur, passes downward to 
the inner tuberosity. The -posterior border, called linea as-pera 
is the most distinct of the three. It may be considered as con- 
sisting- 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 and an external lip, and a roug-h intervening- space, 
which are intended for muscular attachments. Above it 
divides into three lines : one winds around about a quarter of 
an inch below the lesser trochanter to become continuous wnth 
the spiral line of the femur ; one passes upward to the base of 
the lesser trochanter ; while the vertical passes upward and 
outward to join the posterior border of the g-reater trochanter. 
Below it subdivides into two ridges, which are known as the 
two condyloid ridges. These two ridges diverge from each 
other, enclosing the -popliteal space, a smooth triangular 
space found at the lower extremity of the shaft, the base of 
which is directed downward to the condyles and the apex up- 
w^ard 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, and rising either in 



OSTEOLOGY. 45 

the linea aspera or upon its external surface close to the linea 
aspera, is found a larg-e nutrient foramen, which is directed 
obliquely upward and outward. 

The Patella. 

The Patella (Iv. Patella, a small pan), or knee-pan, is a 
sesamoid bone situated on the front of the knee joint, devel- 
oped in the tendon of the triceps extensor cruris. It presents 
for examination two surfaces, anterior and posterior, two 
extremities, superior and inferior, and two borders, internal 
and external. The aiiterior surface is rough, marked by a 
number of vertical lines and a number of nutrient fora- 
mina. The posterior surface is smooth and articular. 
Near its middle it presents a prominent vertical ridg-e ; 
and on either side of this a depression, also articular, in- 
tended for the reception of the condyles of the femur. The 
posterior face forms the receiving- surface for the trochlea. 
These depressions are dissimilar in size and shape ; and cor- 
respond to the dissimilarity of the condyles of the femur, the 
outer depression being larger and more nearly circular, while 
the inner is smaller and more oval in outline. The upper 
extremity of the bone is blunt, rough, and marked by a trans- 
verse ridge ; the lower extremity, smaller and more pointed, 
is roughened. Of the borders, the external is thinner and 
sharper than the iutcrnal. Both are roughened for the attach- 
ment of the tendinous fibres of the triceps. 

The Tibia. 

The Tibia (Z. Tibia, a flute or pipe) is a long bone, con- 
sisting 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 
diameter is much greater than its antero-posterior. It pre- 
sents upon its summit two shallow articular cavities, called 
glenoid cavities, intended to receive the condyles of the femur, 
and in correspondence with them are dissimilar in shape, the 
outer being circular and the inner oval. The inner cavity has 
its long diameter antero-posterior ; the outer cavity is shal- 



46 DESCRIPTIVE ANATOMY. 

lower, as well as being- circular in outline. These cavities 
are separated from one another by a prominent projection, 
which is called the spine of the tibia. This spine is bifurca- 
ted ; and is situated nearer to the posterior than to the anterior 
surface of the extremity. In front and behind the spine is 
seen a roug-hened, non-articular space, which is intended for 
lig-amentous attachment. On the front of the bone, about an 
inch below the articular cavities, is a roug^h triang-ular space, 
below which is seen a projection, called the anterior tubercle 
of the tibia. This tubercle is smooth above and roug-h below, 
the rougfhened lower portion being intended for muscular at- 
tachment. That expanded portion of the bone upon which 
the g-lenoid cavities rest is known as the tuberosity of the ti- 
bia, internal and external. The internal tuberosity, somewhat 
more prominent than the external, is roug-h, and marked near 
its posterior portion by a deep transverse, or antero-posterior 
groove. The external tuberosity is roug-hened, as is the inter- 
nal, and posteriorly is marked by a flat, circular, articular 
facet, which is directed downward, outward, and backward, 
and is intended for articulation with the upper extremity of 
the fibular. Behind, the tuberosities are both roug-hened for 
ligamentous attachment. 

The Lozver 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 mallet). It corresponds nearly to 
a styloid process. This internal malleoeus presents two 
surfaces, two borders, and an extremity. Of the sur- 
faces, the internal 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 downward and forward, and has upon it a 
well-marked groove for the transmission of a tendon. The 
extremity is blunt ; and is marked behind by a pit-like depres- 



OSTEOLOGY. 47 

siou. On the outer surface of the lower extremity is a trans- 
verse depression, sometimes articular, more g-enerally roug-h- 
ened, which receives the lower extremity of the fibula. The 
lono- diameter of this depression is directed from before back- 
ward ; and leading- upward from it are two lines, which 
shortly converg-e, enclosing* between them a roug-h triang-ular 
space for the attachment of interosseous lig-aments. The 
anterior aspect of the lower extremity is roug"hened for lig'a- 
mentous attachment, while the posterior, also roug-hened, is 
marked by a vertical groove. The summit presents an artic- 
ular facet, continuous with the one on the outer face of the 
internal malleolus, and intended for articulation with the upper 
surface of the astrag-alus. This facet is broader externallj'" 
than internally, and broader in front than behind. It is con- 
cave from before backward, and nearly flat from side to side. 
The Shujt 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 g-enerally somewhat twisted, 
particularly in the neg-ro race; and is bowed, convex internally 
and concave externally. The internal surface is broad above, 
becoming- slig-htly narrow below; is convex both from above 
downward, and from before backward; and is subcutaneous. 
The external face, which is concave from above downward, is 
marked by a vertical g-roove close to the external border of the 
bone. This face in the lower third curves g-radually forward 
to the anterior face of the bone. The posterior face is broad 
and flat for the upper one-fifth of the bone, becoming- more 
rounded in the middle and flatter and broader in the lower 
portion. At its upper part it is marked by an oblique ridg-e, 
called the Popliteal Line, which extends downward and in- 
ward from the external tuberosity of the bone. Below this 
ridg-e the posterior surface is marked about its middle by a 
■vertical ridg'e, which exists only for about the middle of the 
bone, disappearing- in the lower portion. Near the commence- 
ment of the vertical ridg-e, g-enerally on the posterior surface, 
is found a larg-e nutrient foramen, being- in fact the larg-est in 
the body, which conveys the blood to the interior of the bone. 



4S DESCRIPTIVE AXATOLIY. 

Of the borders the 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 ante- 
rior border of this projection. The internal border, separating- 
the internal 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 com- 
mences above at the outer malleoeus. in :r : nr of the articular 
facet for the Qbnla. It is the inter :s-r j.s : r i-r, It is indis- 
tinct above, well marked in the riiiir r:: n of the bone, 
and at the low^er extremity divides iiit t v linci, ^rhich form 
the boundaries of the triangular 5p3.cc rnrnrioned as being- on 
the loTver extremity of the bone. 

The Fibula, 

The Fibula (ILr. Fibiilc. ?- cli-.; is the outer and more 
sienirr : tiie two bones formina; the skeleton of the leg. It 
is 1 i : ::^ ;: : ne, having" of course a shaft and two extremities. 

The Upper Extremity, or head, is club-like in outline, and 
presents :n it- upper inner aspect an articular facet, the con- 
: :ur :: v hi :: n.ries in different bones. It is circular in 
form usually sliofhtly concave, but it may be flat and looks 
upward, forward and inward. It is intended for articulation 
\^ith a similar facet on the outer tuberosity of the tibia. 
The outer aspect of this extremity is roug^hened for muscular 
and ligamentous att2.c"nrnent, and terminates above in a blunt 
projection, called the styloid proce \ ^bula. 

The Loixer Extremity is usually spinen :f as the External 
Malleolus. It i- iir^cr ir : n: r- pointed than the upper and 
is indistinctiip trimgiilar. It may be described as consisting of 
internal and external surfaces, anterior and posterior borders, 
and an apex. The outer surface is prominent, convex, rough 
and subcutaneous. The internal surface is articular through 
a part of its extent : mi both above and below the articular 
surface is found 2. rinpitrned space — that above for the inter- 
osseous ligaments v, nich. i::nch it to the fibula, that below for 



OSTEOLOGY. 49 

lig-amentous fibres binding- it to the foot. The articular space 
is intended for the lateral aspect of the astragalus, and occa- 
sionally extends upward to the fibula. The posterior border 
is nearh' straig-ht, is much thicker than the anterior border, 
and is marked by a shallow g-roove for the passag-e of tendons. 
The (Ditcrior border is narrow and convex, and slopes obliquely 
from above downward and backward. The apex is a blunt, 
roug"hened point. 

The Shaft of the bone is twisted, presenting" what is known 
as the curve of torsion, so that its faces and borders chang-e 
their relative positions in the diiTerent portions of the bone. 
The faces ma}- 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, slig-htly curved above, marked by a ridg-e 
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, be- 
comes flat and internal at the lower one-third of the 
bone. Of the borders, the anterior is slig-htly 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 posterior border of the external malleolus, while the 
other, more slig-htly marked, passes to the anterior border 
of the external malleolus, leaving- between them a triangular 
spaca, 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 posteri- 
or in the lower third of its course, and passes to the back of 
the external malleolus. The /;//6'r;/«/Z'('>r(^/rr commences at the 
back of the head of the fibula, becomes the interosseous ridge 
in the middle of the bone, running down upon the internal face, 
and twists to the front of the bone in the lower portion of its 
course. 

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 

Deji Anat— 4 



50 DESCRIPTIVE ANATOMY. 

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, a set of long- bones forming- 
the Metatarsus, and the Phalang-es. 

The Tarsus. 

The Taisiis consists of seven bones: The Os Calcis, Astra- 
g-alus. Scaphoid, Cuboid, and three Cuneiform bones, known 
as E^xternal, Middle, and Internal, sometimes as First, Second, 
and Third. These bones are arrang-ed in two rows: the first 
row, or posterior row, consisting- of the os calcis and astrag-alus 
the remaining- five bones forming- the second row. 

The Bones of the First Row. 

The Os Calcis (Iv. Calx, the lieel) forms the posterior abutment 
of the arch of the foot, and is known as the heel bone. It pre- 
sents for examination two extremities, anterior and posterior, 
and four surfaces, superior, inferior, and two lateral. The 
upper sicr/ace consists of two portions, one behind the other. 
The posterior one-half 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 g-roove. Of these surfaces, the larg-er and more 
posterior is convex in outline, and oblique in direction. Its 
long diameter is directed from before downward and outward; 
and it corresponds to the concave receiving- cavity on the infe- 
rior surface of the astragalus. The anterior is an oblong 
articular facet, concave from above downward and outward, 
the direction of its long diameter ; and intended for the recep- 
tion of the convex articular facet on the lower surface of the 
astragalus. The groove which separates the two surfaces is 
called the Sulcus Calcanei (Iv. THe furrow of the heel), and is 
directed like the surfaces : that is, downward and outward. 
The inferior surface is rough, narrow, and non-articular; and 
presents near its posterior extremity two tuberosities, of which 
the internal is the larger. The anterior part of the inferior 
surface is hardly more than a rough and rounded border. The 



OSTEOLOGY. 51 

external surface is convex througfhout its course, is very roug^h 
for the attachment of ligaments; and is marked by two gfrooves, 
one above the other, separated by a slig-ht roug-hened ridg^e. 
These g-oooves are intended for the transmission of tendons. 
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 
■process of the os calcis. The deep concavity on the internal 
surface 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 g-reater portion of 
the anterior one of the two facets on the superior face of the 
bone. The posterior extremity is quadrilateral in outline, 
roug-h at its lower portion, smooth above for the play of the 
bursa between itself and the tendon Achillis. The aiiterior 
extremity is concavo-convex, forming- a saddle-shaped articula- 
tion between this bone and the cuboid. This surface is con- 
cave from above downward and outward, convex in opposite 
direction. 

The Astrag-ulus, the second bone of the first row, lies 
between the tibia above, the two malleoli at the sides, and 
the OS calcis below. It presents like the os calcis four sur- 
faces and two extremities, the surfaces, as is the case with the 
OS calcis, being- superior, inferior, and two lateral, while the 
extremities are anterior and posterior. The superior surface 
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 is narrow behind and broad 
in front, a fact which g-overns some of the movements of the 
ankle-joint. It is composed of a central depression with two 
elevated ridg-es, one upon either side, or, in other words, it is 
a trochlear surface. The inferior surface is in the main artic- 
ular, consisting- of two facets. The posterior facet is quadri- 
lateral and concave, its long- diameter directed downward and 
outward ; and corresponds 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 down- 
ward and outward ; and it corresponds to the concave facet on 



52 DESCRIPTIVE ANATONY. 

the OS calcls. Between these two articular surfaces is a deep 
oblique g-roove, running" downward and outward, which is 
called the Sulcus Tali. This sulcus corresponds in position 
to the sulcus calcanei ; and when the two bones are articula- 
ted, 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 di- 
rected from before backward, continuous with the articular 
surface on the superior face of the bone, and intended for ar- 
ticulation with the internal malleolus. Below^ this articular 
facet is a rough depression for ligamentous attachment ; and 
the remainder of the internal surface is likewise roug-hened. 
The external surface is triang-ular or pyriform, the base up- 
ward and apex downward. It is concave from above down- 
ward, sHg-htly convex from before backward, and is continu- 
ous with the articular facet on the superior surface of the 
bone. It is intended for articulation with the external mal- 
leolus. Below the articular surface is a slight roug-hness for 
ligamentous attachment. The anterior extremity, or head of 
the bone, is oval, convex, and articular ; the long diameter of 
the head, slightly oblique in direction, is from above down- 
ward and inward, and is intended for articulation with the 
cavity found 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 superior articular surface ; 
and by an oblique groove, which extends downward and in- 
ward, and is continuous in the articulated foot with the concave 
inner face of the os calcis. 

The Bones of the Second Row. 

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, 



OSTEOLOGY. 53 

superior, inferior, external, and internal, and an anterior and 
a posterior extremity. The upper surface looks upward and 
outward, and is roug-h 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 ridg-e, 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 
attachment. The peroneal ridge terminates externally in 
the tuberosity, a somewhat rounded blunt projection of bone, 
which constitutes one of the landmarks of the foot. The in- 
ternal 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. The external 
face is in reality only a border. It is narrow and rough- 
ened, presenting the projection of the peroneal ridge and the 
commencement of the peroneal groove. The anterior extrem- 
ity 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 articulation with the fourth 
and fifth metatarsal bones respectively. The posterior ex- 
tremity is concavo-convex, being concave from above downward 
and inward and convex from within outward, to correspond with 
a similar articular surface on the anterior extremity of the os 
calcis. At the junction of the inferior and internal surfaces 
tl.is extremity is prolonged backward and inward, so that 
the OS calcis apparently rests partly upon a prolongation of 
the cuboid. 

The Scaphoid, the second bone of this row, presents an 
anterior posterior, superior, and inferior surface ; and in- 
ternal 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 



54 DESCRIPTIVE ANATOMY. 

for articulation with the head of the astragalus. The anterior 
surface has three articular facets, separated by two slig-htly- 
marked vertical ridg-es. These facets articulate with the three 
cuneiform bones. The most internal, which approaches the 
nearest to the inferior surface of the bone, is large and slight- 
ly triangular; the central, quadrilateral; and the external, also 
nearly quadrilateral in outline, is oblique in its direction. 
Thtszcj)e7'ior surface \^ convex from side to side; and roughened 
for ligamentous attachment. The inferior surface, narrower 
than the superior, is also roughened for ligamentous attach- 
ment. The inner extremity of the bone is a blunt projection, 
the tuberosity of the Scaphoid which, with the tuberosity of the 
internal cuneiform, furnishes another of the landmarks of the 
foot. The(9«/er extremity is usually roughened; but occasion- 
ally presents a small facet for articulation with the cuboid. 

The Internal Cuneiform, 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 matatarsal 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, intended for 
articutation 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, 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 terminates pos- 
teriorly in the blunt elevation or tuberosity of the internal 
cuneiform. The superior face is scarcely more than a rough 
narrow border. 

The Middle Cuneiform lies between the internal cunei- 
form on its inner, and the external cuneiform on its outer 
side, the scaphoid bone and the second metatarsal in front. 



OSTEOLOGY. 55 

Its superior surface, much broader than its inferior, is roug-h 
and irreg"ular for the attachment of lio-aments. The inferior 
surface, scarcely more than a border, is also roug^hened. The 
iuterual surface presents a reversed Iv-shaped facet similar to 
the one found upon the internal cuneiform. The exter- 
nal surface has an articular facet upon its posterior portion ; 
but is non-articular in front, being- roug-hened for the attach- 
ment of the interosseojus ligament. The posterior surface is 
smooth, slightly quadrilateral in outline for articulation with 
the middle facet upon the scaphoid. The anterior surface is 
articular, convex slig"htly from side to side for articulation 
with the base of the second metatarsal bone. This bone is 
more distinctly wedg-e-shaped than the other two cuneiform 
bones. 

The External Cuneiform is intermediate in size between 
the internal and the middle. It lies with the middle cunei- 
form 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 slig"htly bent upon itself, so as to be 
concave internally and convex externally. Its superior sur- 
face is roughened like the preceding* tarsal bones ; its infe- 
rior surface, narrower than the superior, is likewise rough 
for lig-amentous attachment. The internal surface is slightly 
concave from before backward ; and presents an articular 
facet near its posterior end for articulation with the middle 
cuneiform. In front of this facet it is roughened for the 
interosseous ligfament. Near the anterior extremity is a 
very slight facet for articulation with the lateral aspect of the 
second metatarsal b^ne. The exteriial surface has an oblong 
facet near its upper posterior portion, corresponding" to the 
slight facet which is found on the inner face of the cuboid. In 
front of this the external surface is roug-hened for lig*amentous 
attachment. Posteriorly it presents a smooth, nearly flat ar- 
ticular facet, which is cut ol>li(]uelyv,u as to face backward and 
inward, thus disting-ui.shing- it from the other cuneiform bones, 
whose posterior extremities are cut squarely. The anterior 
surface, or extremity, presents a smooth quadrilateral articu- 
lar facet for articulation with the third metatarsal bone. 



56 DESCRIPTIVE ANATOMY. 



The Metatarsal Bones. 

The Metatarsal Bones present the same g-eneral charac- 
teristics as the metacarpal. They are long- bones, pre- 
senting" 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 aspects, its superior and inferior surfaces being- roug-h 
and square. Its head, much smaller than its base, presents on 
its summit an articular facet, which is convex, with its long- 
diameter vertical. Behind the head is a slightly constricted 
portion, 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. Near the plantar 
aspect the head is grooved for the transmission of tendons. 
The shaft of the bone is narrow ; and presents a dorsal sur- 
face 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 metatarsal bones ; and the inferior border is rounded 
and indistinctly marked. 

The First metatarsal bone is very massive. Its poste- 
rior extremity presents a concavo-convex articular surface ; 
and its anterior extremity, presenting a rounded head, is, un- 
like the other metatarsal bones, nearly as larg-e as the posterior 
extremity. 

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. 



OSTEOLOGY. 57 

The Third metatarsal bone presents an articular facet 
on either side, that on the inner side being- divided into two by 
an antero-posterior g-roove. 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 character- 
istic 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. 

Certain g-eneral characteristics enable us to distinguish 
between the metatarsal and metacarpal Ijones. The most im- 
portant is that the metatarsal bones are all about the same 
length, but are slenderer than the metacarpal ; and whereas 
in the metacarpal 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 sing-le excep- 
tion of the first metatarsal, which is disting-uished by other 
marks. 

The Phalanges. 

The Phalang-es of the toes, like those of the fingers, 
are arrang-ed in three rows, except that the great toe has, like 
the thumb, but two phalang-es, the place of the second being- 
taken by the ungual. They resemble those of the hand soclosely 
that a separate description is not necessary. They are smaller 
and shorter than those of the hand, the second phalanx partic- 
ularly being scarcely more than a neck of bone separating- two 
articular extremities, while the ungual phalanx is frequently 
scarcely distinguishable, except that for the first toe. In the 
fifth, or little toe the ungual and second phalanges are some- 
times found ossified together. 

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 posterior division of the skull, and 
is formed by the union of eight bones — occipital, frontal, sphe- 



58 DESCRIPTIVE ANATOMY. 

noid, ethmoid, two parietal and two temporal. These become 
securely ossified tog-ether in mature life, and can be separated 
only in the young- subject. 

Occipital. 

The occipital bone, sometimes called the first cranial vertebra, 
is situated at the posterior part of the cranium, and presents 
for examination two surfaces, four ang-les and four borders. 

The posterior surface, frequently erroneously called exter- 
nal, is convex, and presents above its centre an eminence called 
the posterior occipital protuberance ; curving outward from 
this on either side is a roug-h ridg-e called the superior curved 
line ; passing- downward from the protuberance to a large 
aperture — the foramen magnum — is a sharp ridge, the occipital 
crest ; arching outward on either side from the middle of the 
crest, and concentric with the superior curved line is the infe- 
rior 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, 
articular, 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 poste- 
rior condyloid foramen. In front of the condyle is the anterior 
condyloid foramen. Passing outward from the condyle is a 
rounded elevated ridge, the 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, and presents an antero-posterior ridge, the pharyn- 
geal 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. E)ach 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 



y 



\ 



OSTEOLOGY. 59 

foramen mag"nuiii. At the point where the four arms meet 
there is an eminence called the anterior occipital protuberance. 
Above each lateral arm of the cross there is a shallow depres- 
sion, the cerebral fossa ; below each lateral arm is another 
depression, the cerebellar fossa. At the termination of the 
lower arm is the foramen mao-num, and on each side of this 
the anterior condyloid foramen. In front, and to each side of 
the foramen majs^num is a smooth broad groove for the termi- 
nation of the lateral sinus. In front of the foramen mao-num 
is the basilar process, which, as on its inferior surface, is 
nearly horizontal and quadrilateral, but is here concave to sus- 
tain the medulla oblong-ata. 

The ang-les are superior, inferior and two lateral. The 
lateral ang-les are each situated where the g-roove in the lateral 
limb of the crucial ridg-e, strikes the border of the bone. The 
inferior angle is the truncated extremity of the basilar process, 
and articulates w^ith the body of the sphenoid. 

The superior ang"le juts into the interval formed by the union 
of the posterior superior angfles of the parietal bones. 

The borders are two superior and two inferior, l^ach 
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 below the lateral 
angle and is interrupted about its middle by a protuberance, 
the jugular eminence, in front of which is a depression, the 
jug*ular fossa. 

Parietal. 

The two parietal bones form the upper and most of the lat- 
eral wall of cranium, and are situated between the frontal and 
occipital bones, in front and behind, and the two temporal 
bones laterally. Each bone is divided into tuo snrfaccs, four 
borders, 3.nd Jhur cDi^i^lcs. The cxlcrnal surface is convex and 
presents a decided bulg-e about the middle, the parietal emi- 
nence ; through this is seen running the temporal ridg-e, arch- 
ing across this bone from the frontal ; below the ridge, is a 
nearly flat surface forming- part of the temporal fossa. Near 



60 DESCRIPTIVE ANATOMY. 

the posterior superior ang-le 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 dig-ital pits for lodging- 
cerebral convolutions, and the arborescent furrows worn by 
the arteries. Along- the edg-e of the superior border is seen 
half of a g-roove, completed by the opposite bone, and 
formed by the long-itudinal sinus. 

The borders are four. The anterior, for articulation with 
the frontal bone, and the -posterior, for the occipital, are serra- 
ted. The superior border, for articulation with its fellow, 
straig-ht, serrated and thick. The inferior border, for articu- 
lation with the squamous portion of the temporal bone, is short, 
curved and beveled at the expense of the outer table. The 
ang-les are four. The anterior superior and the posterior supe- 
rior are rig-ht angles. The anterior inferior is long-, thin and 
marked on its inner aspect by a furrow formed by the middle 
mening-eal artery. '^\^t posterior Inferior is blunt and usually 
marked internally by the g-roove for the lateral sinus. 

Frontal. 

The frontal bone is situated at the front and base of the cra- 
nium. In early life the bone consists of symmetrical lateral 
halves, separated by a vertical suture, which, however, be- 
comes ossified later in life, though the bone could still be de- 
scribed 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- 
2;ontal, or orbito-nasal portion. 

The vertical portion forms the skeleton of the forehead and 
presents two surfaces and a lateral aspect. Upon the anterior 
surface, which is convex, there are seen superiorly a smooth, 
somewhat flattened surface ; below this a bulg-e, called the 
frontal eminence ; below this a broad, shallow, transverse 
g-roove ; below this a transverse ridge, the superciliary ; be- 
tween this and the opposite ridg-e, on the middle line, is a 
prominence called the g-labella, or nasal tuberosity. Below 
the superciliary ridg-e is seen the marg-in of the orbit, called 



OSTEOLOGY. 61 

the supra-orbital ridg-e, which terminates at the inner extremity 
in the internal ang-ular process, and at its outer in the external 
angular process. About the inner third of the supra-orbital 
rldg-e is a notch, sometimes formei 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 arte- 
-riesr-^n the middle line this surface presents superiorly a 
g-roove for the longitudinal sinus, which, as it descends, termi- 
nates in a ridge, at the extremity of which is a small foramen, 
called the foramen coecum. 

The lateral aspect of the bone presents a ridge curving up- 
ward 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 j)artially 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 and concave, 
the concavity being greatest behind the external ang-ular 
process — the lachrymal fossa. It has, just within the supra 
orbital notch, a depression called the fovea trochlearis. 

The upper surface of the orbital plate is convex and rough, 
presenting irregular rough eminences. 

The ethmoidal fissure, the margins of which present several 
half cells, which, when articulated with the ethmoid, complete 
theethmoidal cells, is the rectangular notch separating the 
two orbital plates. 

In front of it is a roughened interval, between the two 
internal angular processes, called the nasal notch, descend- 
ing from the middle of which is a long pointed process, 
the nasal spine. Upon the 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 



62 DESCRIPTIVE ANATOMY. 

frontal sinuses. The frontal sinus, one on each side of 
the middle line, is an irreofular cavity between the 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 
inferior. The siirperior 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 interiorly at the expense of the outer. 

ThezVz/dT/or border is the posterior termination of the orbital 
plates, interrupted in the middle by the ethmoidal notch. It 
is straig-ht and articular with the lesser wing- of the sphenoid. 
At the ang-le of the junction of the two borders, there is a 
rough triangular surface, the sphenoidal triang-le, for articu- 
lation with the greater wing of the sphenoid. 

Temporal Bone. 

The temporal bone is divided for stud}'- into the squamous, 
mastoid and petrous portions. 

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 con- 
cave from above downward and from before backward. It is 
marked by irregular, antero-posterior elevations with inter- 
vening depressions for the convolutions and sulci of the brain. 
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 concave 
from before backward, rough for muscular attachment 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 occu- 
pied by the zygoma and the glenoid cavity. 

The zygoma, or zygomatic process, at its origin from 
the squamous portion, passes outward with a slight in- 
clination forward; but after a course of about one-fourth 



OSTEOLOGY. 63 

of an inch, is twisted upon itself so that the surfaces 
and borders change their relative positions. At its orig-in 
the surfaces are superior and inferior, the first occupied 
by a g-roove, the second b}' 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 surface 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. Pos- 
teriorly, 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 bound- 
ary of the glenoid cavity. The posterior root passes back- 
ward, just above the glenoid cavity and the external auditory 
meatus, and than curving upward forms the continuation of 
the temporal ridge which separates the squamous from the 
mastoid portion. Just after it passes above the gdenoid cavity, 
it sends downward a prominent articular projection, sometimes 
called the middle root of the zygoma, which forms the poste- 
rior boundary of the articulation for the lower jaw. 

Tho. fylenoid cavily \'i concave and oval in outline, its long 
diameter being directed from without back weird and inward. 
it is bounded in front by the eminentia articularis, a smooth, 
rounded, oval articular ridge which is a continuation 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 articular portion and 
a posterior non-articular. The articular portion is limited be- 
hind by the middle root of the zygoma, sometimes called the 
post-glenoid tubercle. 



64 DESCRIPTIVE ANATOMY. 

The semi-circular border is roug-h, thin and sharp above, 
strong-ly 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 
surface ; superior and posterior borders and a roug-h nipple 
like projection, the mastoid process. The interned surface 
presents but one mark of note. It is smooth and has a deep 
g-roove which runs from above downward and backward. It 
is called the fossa sigmoidea. The external surface is roug-h 
throughout and presents near the posterior border a larg-e 
foramen, called the mastoid, which is sometimes found in the 
suture between this bone and the occipital and sometimes is 
altog-ether wanting. 

The Mastoid process is a roug-h, blunt projection of 
bone, marked internally by a deep g-roove, the dig-astric 
fossa, internal to which is a shallower g-roove for the occipital 
artery and known as the occipital g-roove. The interior 
of the mastoid portion is hollowed out into a number of cellular 
cavities. The superior border is roug-h, serrated and nearly 
straig-ht to receive the posterior inferior ang-le of the parietal. 
The -posterior border, longer than the superior, slopes from 
above downward and forward and is roughened for articula- 
tion 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 pos- 
terior. The -posterior surface is the simplest of the three. 
Internal to its middle point it presents an oblique oval open- 
ing, the internal auditory 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. E^xternal to the 
internal auditory meatus and near the posterior border, is seen 
a little slit like aperture which leads to the acqueductus vesti- 
buli. Between the two, and near the superior border, is usu- 



OSTEOLOGY. 65 

ally seen a slig-hter depression which lodg-es a process of the 
dura mater. 

The anterior surface presents near the middle a round 
elevation which marks, the position of the superior semi- 
circular canal ; external to this a smooth concave surface 
forms the roof of the tympanum ; below and in front of the 
bulg-e is a groove leading- outward and backward to an open- 
ing-, the hiatus Fallopii, while at the junction of the squamous 
and petrous portions may sometimes be seen another and slig-hter 
groove, the petrosal. Near the apex of the bone is seen a de- 
pression for the Gaserian g-anglion, 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 roug-h and irreg-ular and has upon it 
eleven points which require examination. Near the apex of 
the bone is a roug-h, nearly quadrilateral surface which g-ives 
attachment 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 forward and inward and downward, pursuing- a course 
parallel with that of the petrous bone, to emerg-e at the apex. 
External and slightly behind this is a smooth, concave surface, 
which encroaches on the posterior border of the bone, called 
the jugfular fossa. On the bony partition separating- the jug-u- 
lar fossa from the carotid aperture, is a small foramen which 
transmits Jacobson's nerve : and on the outer wall of the fossa 
itself is another foramen, smaller in size, for Arnold's nerve. 
Behind and slig-htly internal to the carotid aperture, near the 
posterior border and directly beneath the internal auditory 
meatus, is a small opening", the aqueduct of the cochlea. Exter- 
nal and anterior to the carotid aperture, is a thin, prominent 
tong-ue of bone, which extends outward to become continuous 
with the auditory process, called the vag-inal process. At its 
base this process splits into two sheets, one in front of the 
other, to enclose a sharp pointed projection, the styloid pro- 
cess. This, the long-est of such processes in the body, passes 
downward and slig-htly forward and outward. Behind and 

Des Anat — 5 



66 DESCRIPTIVE ANATOMY. 

external to this is a larg-e foramen in the bone, the stylo- 
mastoid ; while between the vag-inal process and the mastoid 
process is a slig"ht g-roove, the auricular fissure. At the junc- 
tion of the posterior border of the mastoid portion with that of 
the petrous portion, there is a rough articular surface called 
the jugfular 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 petrosal sinus, and 
near the apex of the bone a nptch to lodge the fifth cranial 
nerve. '^\\^ 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 w^ith the basilar process of the 
occipital. 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 
Kustachian 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 
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 spinous process of the sphenoid. 

The Sphenoid. 

The sphenoid occupies a position near the middle of the base 
of the skull, and maybe considered the key-stone of the cranial 



OSTEOLOGY. 67 

arch, since it serves to bind tog; ether all the bones of the skull 
and five of those of the face. It has been likened to a bat with 
the wing's spread out, and is divided for study into a bod}'' twO 
wing's, g-reater and lesser, on either side, and two projections, 
or processes, called the pteryg-oid. 

The body presents six surfaces, superior, inferior, anterior, 
posterior and two lateral. 

The upper surface commences in front in a triang-ular 
spine which, from its articulation, is known as the eth- 
moidial spine of the sphenoid. Behind this projection 
there may sometimes be seen a line or ridge leading- backward 
and a slight transverse ridge, stretching between the anterior 
margins of the optic foramina. Behind this is a broad, trans- 
verse groove, the optic, and behind this a prominent, rounded 
elevation, the olivary ridge or process. Behind the olivary 
ridge is a deep pit-like depression, the sella turcica or pitui- 
tary fossa, overhanging which behind is a square projection, 
the dorsum Ephippii, whose posterior surface, running ob- 
liquely downward and backward is called the clivus Blumen- 
bachii. On either side of the mid-line in front of the sella 
turcica 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 
«-roove extends across to terminate at either end in the corres- 
ponding optic foramen. The olivary ridge terminates at its 
extremities in a small projection, the middle clinoid process, 
which is sometimes 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, be- 
hind by the dorsum ephippii, laterally by the margin of the 
carotid groove. The dorsum sellffi terminates at either angle 
in a rough projection, the posterior clinoid process, sometimes 
connected to the anterior 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 articulated 
skull with the upper surface of the basilar process of the 
occipital. 



68 DESCRIPTIVE ANATOMY. 

The ^posterior surface is rough and square, presenting- 
many nipple-like projections for articulation with the basilae 
process of the Occipital. In advanced life it is ossified to thr 
Occipital. 

The anterior face -^VQsent^ in the middle a prominent, roug-h 
vertical ridg^e 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 roug-h and 
presents near the middle the opening- into the sphenoidal sin- 
uses. The marg-ins of the opening- are roug-h for articulation 
with the OS planum and posterior extremity of the lateral mass 
of the E^thmoid, the latter throug-h the pyramid of Wistar. 

The inferior surface is marked in the middle by the contin- 
uation of the crest, called the rostrum of the sphenoid. The 
rostrum is broad behind, narrow and more prominent in front 
and is received into a fissure on the upper border of the '^j 
Vomer. Oa either side of the rostrum is a smooth surface 
for articulation with theal^ of the Vomer, external to which is 
the vagfinal process for the under surface of each ala, beneath 
which is the g-roove called pteryg-o-palatine, converted into a 
canal of the same name bv articulation with the palate bone. 

The lateral surfaces are almost taken up by the orig-in of the 
g-reater wings. The space just above each wing- is occupied 
by a broad v^nnding- g-roove, 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 formation of the sphenoidal fissure and the inner wall 
of the orbit. 

The Lesser Wings. E^ach lesser wing springs by its per- 
forated base from the junction of the lateral and superior sur- ^ 
faces of the body, and passes outward, to terminate in a pointed 
process near the outer limit of the greater wing. 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 



OSTEOLOGY. 69 

a part of the roof of the orbit and the upper boundary of the 
sphenoidal fissure. The anterior border is thin, straig-ht and 
serrated for articulation with the straig-ht border of the Front- 
al. The posterior, thicker than the anterior, begins internally 
in a bluntly pointed projection called the anterior clinoid pro- 
cess, which passes backward and inward. This border is 
concave and smooth, thinner in the middle than at either ex- 
tremity, and terminates externally in the outer end of the lesser 
wing". The perforation found at the base of the lesser wing is 
the continuation of the optic g-roove of the upper face, is called 
the optic foramen and leads downward, forward and outward 
to the cavity of the orbit. 

The Greater Wing-. The g"reater wing* spring's from the 
lower part of the lateral aspect of the body and passes upward, 
outward and forward. It is divided into four surfaces, 
superior, anterior, external and inferior. The circumfer- 
ence of the g-reater wing- will be described later. The upper 
surface of the g-reater wing- is concave and enters into the for- 
mation of the middle fossa of the skull. It is, consequently 
marked by elevations and depressions corresponding- to the 
sulci and convolutions of the temporo-sphenoidal lobe of the 
brain which it lodg-es. 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 cir- 
cular foramen called, from its shape, the foramen rotundum. 
Its direction is downward, forward and slig-htly 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 down- 
ward and opening- on the inferior face of the g-reater wing-. 
Behind and external to this is found the foramen spinosum, 
also opening- directly downward. The external face enters 
into the formation of the temporal fossa. It is broader above 
than below, slig-htly roug-h for muscular 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 y.ygomatic fossa, is small and quadrilateral 



70 DESCRIPTIVE ANATOMY. 

in shape, looks downward and outward and is slightly rough- 
ened for the attachment of muscles. 

The g-reater part of the anterior face looks into and forms a 
part of, the orbital cavity. It is triang-ular in form, the apex 
directed backward and inward and the base outward, concave 
from above downward, flat from before backward and per- 
forated by one or tw^o small foramina. Just below this portion 
of the anterior face is a small flat surface of bone formino- 
a part of the pteryg-o-maxillary fossa and upon which the 
foramen rotundura 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 again 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 ante- 
rior 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 of the outer border of the upper 
face extending from the pterygoid ridge to the summit of the 
bone. The anterior face is bounded above, for its outer part, 
by a serrated edge forming the anterior boundary of the fron- 
tal triangle ; for its inner part by a part of the upper border 
of the superior surface ; anteriorly or externally, by the ante- 
rior border of the outer face and below by a ridge leading from 
the pterygoid ridge on 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 inferior 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 



OSTEOLOGY. 71 

one entering- into the formation of the sphenoidal fissure the 
other into the spheno-maxillary. The frontal triang-le is 
found at the junction of the upper, outer and anterior surfaces. 
It is bounded in front by the upper border of the anterior 
face; externally by the upper border of the outer face; behind 
b}^ a part of the upper border of the superior surface. 

The Pterygoid Process. The Pterygoid Process springs 
from the junction of the greater wing- and the body near the 
posterior surface of 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 for the pteryg-o- 
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 roug-h articular strip for the posteri- 
or 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, while internal to this 
is the opening- of a small foramen, the pteryg^o-palatine. Below 
and external to the scaphoid 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 
pteryg-oid fossa is deeper and broader at its upper portion. 
The inner plate is longer and narrower than the outer. Its 
internal surface is smooth and forms the outer boundary of the 
posterior nares, its outer, smooth and concave, forms the inner 
boundary of the pterygoid fossa. The anterior border, blended 
with the outer plate, above, presents below 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 outward and backward. The outer plate, 
broader and more massive than the inner, presents an outer 



72 DESCRIPTIVE ANATOMY. 

face which is concave and roug-h to form the inner wall of the 
zyg-omatic fossa, an internal face, roug-h and irregularly con- 
cave, which forms the outer wall of the pteryg-oid fossa; an 
anterior border serrated below for the gfroove on the Palate, 
and a posterior border which is thin, sharp and irregular, 
sloping- obliquely downward and backward. 

The Ethmoid. 

The Ethmoid lies in the middle of the anterior fossa of the 
skull. It consists of a body and two lateral masses. A por- 
tion 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 larg-er portion of the bone is con- 
cealed by surrounding- bones. 

The Siiferior Surface of the body is called the Horizontal 
or Cribriform Plate; and is perforated by numerous small 
foramina. These foramina are arranged in three rows, of 
which the internal and external are fairly distinct, while the 
middle row is irreg-ular and indistinct. The anterior foramen 
of the internal row is a narrow, slit-like aperture for the 
transmission of a 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 g-alli (Iv. 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 bor- 
der is narrow and sharp. Its lateral apects, smooth and 
slightly concave at the lower portion, are marked above by a 
bulging- projection, which varies g-reatly in size in different 
bones. Projecting- from the front of the crista g-alli are two 
small processes, one towards either side, called the alar 
■processes (Iv. Ala, a wing-). 

At each side of the base of the crista Galli is a small fissure 
called the nasal g-roove, or slit. Posteriorly the superior sur- 
face presents a deep notch, the sphenoidal fissure, for the 
reception of the ethmoidal spine of the sphenoid bone. 

Laterally this surface articulates with the orbital plate of 
the frontal bone; anteriorly with the frontal bone by the two 



OSTEOLOGY. 73 

alar processes which complete, posteriorly, an opening" called 
the foramen coecum. 

From the lower surface of the cribriform plate there passes 
downward, on the middle line, a thin sheet of bone called the 
perpendicular lamella, which aids in forming- the septum of 
the nose, articulating- in front with the nasal spine of the 
frontal and with the nasal bones; posteriorly it articulates 
above with the beak of the sphenoid, below with the vomer; 
inferiorly it g-ives attachment to the cartilage of the septum. 
Its faces are g-rooved. 

The lateral mass 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; its upper part is marked by two g-rooves, which 
are the anterior and posterior ethmoidal foramina. The inter- 
nal surface is convex, roug-h 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; below 
the superior meatus is another portion called the middle tur- 
binated bone, which is the upper limit of the middle meatus 
of the nose. The superior surface of the lateral mass pre- 
sents numerous irreg-ular opening's into the cells, of which this 
part of the bone is made up; these are closed in by the over- 
lapping- horizontal plate. Projecting- downward and backward 
from the lower edg-e of the lateral mass is a thin plate of bone 
called the unciform process, which articulates with the ethmoi- 
dal process of the inferior turbinated and helps to close the 
opening- of the antrum maxillare. From the posterior extrem- 
ity of the lateral mass there projects backward a triangfular, 
curled, pointed process, which extends into the sphenoidal cell 
of that side, and, as puberty approaches, becomes detached 
from the ethmoid and ossified to the sphenoid; it is called the 
sphenoidal spong-y bone, or pj^ramid of Wistar. The cells, of 
which the lateral mass consists, are separated by a transverse 
septum into the two sets, the anterior and posterior ethmoidal 
cells; the anterior communicate with the middle meatus by a 



74 DESCRIPTIVE ANATONY. 

tortuous canal called the infundibulum, with which the frontal 
sinusalso communicates. The infundibulum opens into the up- 
per front part of the middle meatus by a larg"e 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 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 pre- 
sent for examination two surfaces, anterior and posterior, two 
borders, internal and external, and two extremities, superior 
and inferior. The anterior face which looks forward and 
slig-htly outward is concave from above downward ; and 
slig-htly convex from side to side, the anterior surface being- a 
little roug-hened and marked by nutrient foramina. The 
^posterior surface, which looks inward as well as backward, 
is convex from above downward ; and marked near the inter- 
nal border by a vertical g-roove. The superior extremity is 
thicker and more massive than the inferior ; and is roug-hened 
and serrated for articulation with the nasal notch of the fron- 
tal bone. The inferior extremity is broader and thinner than 
the superior ; and slopes obliquely from within outward and 
downward, so that v^^hen the two bones are articulated, a pear- 
shaped notch is found between them, its apex upward and its. 
base downward. The internal border is shorter than the ex- 
ternal ; and presents when articulated with its fellow a well- 
defined crest for articulation with the nasal spine of the fron- 
tal and the perpendicular lamella of the ethmoid bone. The 
external border, long-er than the internal, is serrated, thin, and 
sharp for articulation with the nasal process of the superior 
maxillary. 

Lachrymal Bone. 

The lachrymal bones are a pair of small bones, one being- 
found on the inner wall of each orbit in front of the os planum. 
The bone remotely resembles a fing-er nail and hence acquires 
its synonjmi of ung-uis. It presents two faces, two extremities 
and two borders. The external face is divided into an anterior 



OSTEOLOGY. 75 

and a posterior portion, by a vertical ridge, which terminates 
inferiorly in a hook-like process called hamular. The poste- 
rior and larg-er portion 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 verti' 
cal 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. 

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, or inferior spongy bone, is found 
on 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 extremities, 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 aud 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 
meatus of the nose. 

The inferior border is rounded and free, marking the limit 
between the middle and inferior meatus. 

The superior border articulates from before backward with 
the sujjerior maxillary, the lachrymal, the ethmoid and the 



76 DESCRIPTIVE ANATOMY. 

palate bones. It presents three processes, lachrymal, ethmoid 
and maxillary. The lachrymal process is directed upward to 
articulate 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 outward from 
the base of the ethmoidal process and articulates with the 
superior maxilary by hooking- around the orifice of the antrum. 
The ethmoidal process is behind the lachrymal, and is directed 
upward to articulate with the unciform process of the ethmoid. 

Vomer. 

The vomer is a single bone found separating the nostrils 
behind 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 pre- 
sents 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 or the other. 
They are' marked by shallow furrows and by the naso-pala- 
tine groove, which is directed obliquely downward and for- 
ward 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 alae, 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 long-itudinal fissure which 
receives superiorly the perpendicular lamella of the ethmoid, 
inferiorly the triangular cartilage of the septum; the lower 
part is occasionally not fissured but rough. 

The posterior border is concave and free, terminating, 
posteriorly, the septum of the nose. 



OSTEOLOGY. 77 



Malar Bone. 

The malar bone forms the prominence of the cheek, is 
somewhat quadrang-ular and presents for examination four 
processes and a body with two surfaces and four borders. 

The anterior, or external face is convex and has several fora- 
mina opening" on it, called malar. 

The posterior, or internal face is smooth and concave, 
entering- into the temporal fossa above and the 2jyg-omatic be- 
low. 

T\iQ frontal f>rocess projects upward to articulate with the 
external ang-ular process of the frontal bone. The orbital 
firocess 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 ar- 
ticulates with the orbital plate of the superior maxillary bone ; 
between these two articulations there is often seen the narrow, 
rounded, non-articular anterior extremity of the spheno-max- 
illary fissure. This process presents the opening-s into one or 
more small canals, temporo-malar, which extend to the anterior 
surface of the bone and some usually to the posterior surface. 

The maxillary froccss is roug-h and triang-ular, articulating* 
with the superior maxilla. 

The 2yg-o?jiatic process extends backwards, is long- and nar- 
row and articulates with the zyg-omatic process of the temporal. 

The superior border is concave, smooth and rounded, and 
forms part of the marg-in of the orbit. 

The injcrior border is straig-ht and continuous with the 
lower edg-e of the zyg-oma. 

The anterior border is straig-ht and roug-h to articulate with 
the superior maxilla. 

The posterior border is sinuous and continuous with the 
temporal ridg-e above, and below with the upper edg-e of the 
zygoma. 



78 DESCRIPTIVE ANATOMY. 

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. E)ach bone m-ticulates with the frontal and 
etliinoid., and all the hones of the face except the inferior 
maxillary . The bone is divisible into a bodya.r\.^ four f>rocesses. 

The body is irregfularly quadrilateral, is hollowed out into a 
cavity called the antrum of Hig*hmore, or antrum maxillare, 
and presents four faces — anterior^ superior, -posterior ^ inte^-nal. 

The anterior or facial surface is somewhat concave and 
presents about its centre a depression, called the canine fossa, 
which is limited internally by a vertical ridg^e, the canine 
ridg-e; on the inner side of the canine ridg^e 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 edg-e of the nasal fossa: below by the alveolar process; 
externally by the malar process and a ridg-e descending- from 
it ; superiorly by the margfin of the orbit. 

The posterior or zyg-omatic surface is chiefly occupied by a 
roug-h bulg"e, the tuberosity of the superior maxillary bone; it 
presents numerous small foramina, and at its lower part a 
toug-h oval surface; above and internal to this is a smooth spiral 
g-roove, which, with a similar g-roove on the palate bone, forms 
the posterior palatine canal. 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. 

The superior or orbital surface forms the floor of the orbit. 
It is formed of a thin triang-ular plate of bone, is smooth, 
sloping- downward and forward, and marked from behind for- 
ward, by a g-roove, 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 roug-h edge 
for articulation from behind foriuard, with th.Qpalate, ethmoid 
and lachrymal bones; anteriorly it is limited by the lower 



OSTEOLOGY. 79 

marg-in of the orbit, internally, and externally, by a roug"h 
border for articulation with the malar bone; externally it is 
separated from the posterior surface by a rounded border on 
which beg"ins the infra-orbital canal by a notch ; this border 
forming-, in the articulated skull, the lower marg-in of a fis- 
sure, the spheno-maxillary. 

The internal or nasal surface aids in forming- the outer wall 
•of the nose, and presents a larg-e irreg-ular aperture leading- 
into the antrum of Hig-hmore ; this aperture is much reduced 
by articulations with neig-hboring- bones,, J)alale, ethmoid, lach- 
rymal and inferior turbinated. The antrum is indistinctlj'- 
triangular ; in it are seen numerous vertical g-rooves 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 g-roove, the sulcus lachrymalis. This face is 
limited above by the nasal process, in front, and behind this 
by a roug-h cellular edg-e for articulation with the lachrymal 
and ethmoid bones; interiorly is the horizontal palate process, 
which may be said to divide it into two portions, the part be- 
low terminating- in the alveolar process and the part above 
forming- the inferior meatus of the nose. The posterior bor- 
ber is roug-h for articulation with the palate bone. The ante- 
rior edg-e is sharp and concave and forms the marg-in of the 
anterior nares. 

The four processes are nasal, malar, -palate and alveolar. 
The nasal process is a long-, thin, triang-ular projection form- 
ing- a part of the wall of the nose and presenting- three borders 
and tzijo surfaces. 

The anterior border is convex, thin and serrated for articu- 
lation with the nasal bone. 

The posterior border is thick and g-rooved, the posterior 
marg-in of the process is roug-h for articulation with the lacry- 
mal bone ; the anterior marg-in is rounded, continued into the 
marg-in of the orbit, and presents below a small tubercle. 
This g-roove, in the articulated skull, is formed into a canal for 
lodg-ing- the nasal duct, and is nearly vertical, being- slig-htly 
oblique backward and outward. The upper border is blunt 



80 DESCRIPTIVE ANATOMY. 

and serrated for articulation with the frontal bone, its internal 
ang"ular process. 

The external face is concave and marked by small foramina. 

The internal face is crossed from behind forward by two 
roug-h ridg-es, crista turbinalis inferior and superior, the 
former articulating- with the inferior turbinated and the latter 
with the ethmoid. Above the superior turbinated crest the 
surface is rough for articulation with the ethmoid ; between 
the two crests it is smooth and concave, entering- into the mid- 
dle meatus of the nose. 

The malar -process forms the upper part of the boundary'- 
between the anterior and posterior faces. It is concave both 
in front and behind, triang-ular in outline and its summit is 
rough for articulation with the malar bone. 

Tht 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 transversel}'- 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 g-roove. 
Its lower surface is also concave, but /roug-h, marked by nu- 
merous shallow depressions and by a g-roove externally, which 
runs from behind forward. The inner border is roug-h to ar- 
ticulate with its fellow on the opposite side ; it is thicker ante- 
riorly than posteriorly, and its upper edg-e is raised into a 
ridg-e, or crest, which is slig-htly averted, so as to produce, 
when the bone is articulated, a narrow g-roove, for the recep- 
tion of the vomer. Towards the front the inner border, in 
its lower part, presents a g-roove, which sinks into the bone 
above to communicate with a foramen on the upper surface, 
the anterior palatine. In front the inner border terminates in 
a slender, pointed process, which, united with a similar ©ne 
on the opposite bone, forms the anterior nasal spine. 

The anterior border of the process is the thin concave mar- 
g-in of the nose, the nasal notch. 

T\i& posterior border is straight and serrated for articulation 
with the horizontal plate of the palate bone. 



OSTEOLOGY. 81 

The areolar process projects downwards from the lower, 
outer part of the bone, and forms about a fourth of the circum- 
ference of a circle. It is marked by sockets for eight teeth, 
with interv^ening- septa. 

Palate Bone. 

The palate bone enters into the formation of the orbits, the 
nasal fossa? and the roof of the mouth. It is divided into hori- 
zoiital and vertical, or perpoidicular portions, or plates. 

The horizontal -portion 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 con- 
cave 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 
process of the superior maxillary. 

The posterior Ijorder is smooth, concave and free, having its 
inner extremity prolonged backwards by a slender, sharp pro- 
cess, which with asimilar projection 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 articu- 
lated, a slight groove for the reception of the vomer. 

The vertical plate is irregularly quadrangular and presents 
two faces, internal and external, and three borders, superior, 
anterior and posterior. The internal surface presents two 
transverse ridges, the superior and inferior turbinated crests; 
the inferior to articulate with the inferior turbinated bone, 
and the superior with the middle turbinated bone of the eth- 
moid. 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 exteriml surface is, to a great extent, rough for articu- 
lation with the internal face of the superior maxilla ; but at 
Des Anat — 6 



82 DESCRIPTIVE ANATONY. 

its Upper back part there is a smooth portion, which forms a 
part of the spheno-maxillary fossa. At the posterior part of 
this face is a vertical g-roove, converted into the posterior pala- 
tine canal by articulation with the tuberosity 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 hig^her than the sphen- 
oidal, 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 face articulates with the orbital surface of the 
superior maxillary. 

^h.^ posterior face articulates with the sphenoid bone. 

The internal 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 face forms a part of the inner wall of the 
spheno-maxillary fossa. 

The superior face forms the back part of the floor of 
the orbit. 

The sphenoidal process is a thin plate of bone, inclining- in- 
ward as it ascends, and presents three faces^ — superior, ex- 
ternal and internal — and two borders — anterior and posterior. 

The superior face articulates with the sphenoid bone and 
presents a g-roove, 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 ptery- 
goid process of the sphenoid. 

The internal face is free and forms part of the outer wall of 
the nasal fossa. 



OSTEOLOGY. 83 

The anterior border of the process is the posterior boundary 
of the spheuo-palatine notch. 

The -posterior border of the process articulates with the 
pter3^g-oid process of the sphenoid bone. 

The anterior border of the perpendicular plate is irreofular, 
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 openino- into the antrum 
maxillare. 

The -posterior border of the perpendicular plate is g-rooved 
and articulates with the pteryg-oid process of the sphenoid. 
At its lower part is a process, the pteryg-oid process, or tuber- 
osity of the palate bone. It is triang-ular, is directed down- 
ward and backward and outward, and fits into the interval 
between the two plates of the pteryg-oid process of the sphenoid. 
Descending-themiddleof the tuberosity, posteriorly, isa smooth 
gToove, which, when the bone is articulated, forms part of the 
pteryg-oid fossa; on each side of this g-roove is a roug-h g-roove, 
which articulates with the corresponding- plate of the pteryg-oid 
process of the sphenoid. Kxternally the tuberosity is roug-h 
and articulates with the superior maxilla. The opening-s of 
numerous canals, the accessory posterior palatine canals, are 
seen on the tuberosity, and it is perforated vertically throug-h 
its base by the posterior palatine canal. 

The Inferior Maxilla. 

The inferior maxilla, 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 portion, the 
ramus, and a horizontal portion, which is one half of the body 
of the bone. 

The j9o</y is of a horse-shoe shape; and presents external 
and internal surfaces, superior and inferior border's. The 
surfaces do not look directly outward and inward ; but the 
external inclines outward and forward, and the internal inward 
and backward. The external surface is convex from side to 
side, concave in some ]K)rtions, from above downward. 

In front, on the mid-line of the body, is a vertical ridg-e, 



84 DESCRIPTIVE ANATOMY. 

the Symphysis Menti (Iv. Mentiim, the chin), or Crista Men- 
talis, which as it descends spreads out so as to form a triangu- 
lar projection, the meiital -process, which forms the prominence 
of the chin. E^xternal to this symphysis is a depression, 
called the Incisive Fossa ; and just beyond this is a larg-e 
and well-marked foramen, the Mental Forameji. E^xtending- 
backward and upward from the mental foramen is a promi- 
nent ridge of the bone, which becomes continuous with the 
anterior border of the ramus, called the External Oblique 
Ridge. 

The Internal surface is concave from before backward, 
irregular in outline from above downward. On the mid-line 
of the internal surface is a vertical groove corresponding to the 
symphysis, on either side of this groove are seen two tuber- 
cles, one inferior and one superior, both a little below the 
middle point of the groove ; which are known as the Genial 
Tubercles , superior and inferior, sometimes called the Spines 
Men tales. 

They are very irregular in formation : sometimes all four of 
them coalesce into a singde roughened process ; sometimes 
there are two flat ones on either side of the mid-line ; and 
occasionally the four are distinctly seen. External to the 
genial tubercles is a slight depression, which in the fresh 
state lodges the sub-lingual gland. E^xternal to and below 
the tubercles, is a slighter depression, called the Diga.stric 
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 Submaxillary Fossa. 
The upper border of the bone is called the Alveolar Process 
(L. Dim. of Alveus, a cavity) ; and presents the depressions 
for sixteen teeth, these sockets being separated from one 
another by intervening bony septa. The lozuer, or basilar, 
border is slightly everted, strong rounded and smooth. It is 
the most prominent portion of the bone in the living man. Usu- 



OSTEOLOGY. 85 

ally about an inch in front of the ang-le of the jaw this border 
presents a slig-ht g-roove, across which passes the facial artery. 
The Ramus is a quadrilateral projection of bone, which ex- 
tends nearly vertically upward, almost at rig-ht angles with 
the body of the bone. Its obliquit}^ varies with the different 
periods of life. The ramus is divided for study into two sur- 
faces, external and internal, and four borders, anterior, pos- 
terior, superior and inferior. The external surface is flat, is 
slightly roug-hened 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, above which is seen the 
opening of a canal. Above this opening there is a slight 
groove. The foramen leads into a canal which extends 
through the bone, the Dental Canal, and the canal termi- 
nates at the mental foramen on the external surface of the 
body. It is so located as to pass in close contact with the roots 
of the teeth, and lodge the blood-vessels and nerves which 
supply the fangs of each one of the teeth of the lower jaw. 
The projection of bone which guards the foramen below 
and in front is called the Lingula. 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 up- 
ward continuation of the external oblique ridge; while the inner 
lip is an abutment that rises from the termination of the 
alveolar process, and becomes nearly continuous with the 
mylo-hyoid ridge on the inner face of the body. The 
posterior border is more rounded and thinner than the ante- 
rior, extending above into one of the projections of the upper 
border, and below terminating at the angle of the jaw. The 
hnjer 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 



86 DESCRIPTIVE ANATOMY. 

roug-hened for muscular attachment. The superior border 
consists of two projections, an anterior and posterior with an 
intervening- notch, the sigmoid. Of these projections the ante- 
rior is called the Coronoid Process, while the posterior is de- 
scribed as the Condyle of ih.Qjazv, the notch between the two 
being- called the Sigmoid. The Coronoid Process is thin, 
triang-ular in outline; presents an anterior border, which is 
continuous with the outer lip of the g-roove. on the anterior 
border of the ramus, a posterior thinner and sharper border, 
continuous with the sigmoid notch, and a blunt point, the 
extremity, which is received into the fibres of the Temporal 
muscle. The sigmoid notch is concave from before backward, 
its edg-e 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." 

This 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 por- 
tion of the temporal bone. The neck of the condyle, constric- 
ted 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 ag-e 
it nearly prolong-s 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. 

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 g-eneral. 

The skull is divisible into five reg-ions: superior, inferior, 
anterior and two lateral. 



OSTEOLOGY. 8/ 

Superior Region. 

The superior reg^ion or vertex, is bounded in front by the 
frontal eminences, on each side by the temporal ridg^e, and be- 
hind by the posterior occipital protuberance and the superior 
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 oc- 
cipital 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 sagfittal suture, which terminates posteriorly in 
the lambdoid suture. The parietal 'foramen may be seen on 
each side of the sag-ittal 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 g-roove, for the 
superior long-itudinal 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 edg-es of this g-roove are seen several 
pits for lodg-ing- the Pacchionian bodies, and external to these 
dig-ital pits for the convolutions of the brain; numerous arbo- 
rescent arterial furrows are also seen. 

Lateral Region. 

The lateral reg-ion is subdivided into four portions — mastoid, 
tem.poral, zyg-omatic and spheno-maxillar}-. 

Mastoid Portion. 

The mastoid portion of the lateral reg-ion 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 g-lenoid fossa, which 
is bounded above by the posterior root of the xyg-oma, behind 



88 DESCRIPTIVE ANATOMY. 

by the middle root and vag-inal process, and in front by the 
anterior root of the zygoma. It is crossed transversely by the 
fissure of Glaser, the surface in front of the fissure being- 
articular and that behind rough; where the roots of the zygoma 
meet is the tubercle. 

Temporal Portion. 

The temporal portion of the lateral region is also called the 
temporal fossa. Its upper 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 process of the frontal 
bone and the malar bone. Below, it terminates at the zygoma 
without and the pterygoid ridge within. Its constituents are 
furnished by the frontal bone, the malar bone, the greater wing 
of the sphenoid the parietal bone and the squamous portion of 
the temporal bone. 

Zygomatic Portion. 

The zygomatic portion 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 
the squamous portion of the temporal bone; \n 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 spheno-maxillary, and one vertical, the 
pterygo-maxillary, the one being at right angle to the 
other. The spheno-maxillary fis«ure is seen by looking- into 
the orbit; it is situated at the lower part of its outer wall 
posteriorly, betw^een the greater wing of the sphenoid above 
and the orbital plate of the superior maxilla below, terminating, 
frequently, in the malar bone anteriorly; the posterior termina- 
tion is at the point where the pterj^go-maxillary fissure begins, 
which descends between the tuberosity of the superior maxillary 
in front and the pterygoid process behind. 



OSTEOLOGY. 89 

Spheno-Maxillary Fossa. 

At the point of junction of the two fissures is a small fossa, 
the size of the end of the little fingfer, called the spheno-max- 
illary fossa ; it is thus formed : above is the flat surface just 
at the base of the pteryg'oid process anteriorly ; behind is the 
pteryg-oid process, in/ro;^/is the superior maxilla; internally 
is the perpendicular plate of the palate bone. There arey^z-e 
foramina foiDid \w this fossa. Three of them are found on 
the upper posterior wall, i. e., on the flat surface at the base 
of the pteryg-oid process ; they are — 1st, foramen rotiindum ; 
2nd, pter}\^oid, or Vidian \ 2vdi,ptery§'o-palatine ', on tho^ in )ier 
wall is seen the 4th, spheno-palatine\ and 5th, iiiferiorly, is seen 
the opening- into the posterior palatine canal, with accessory 
posterior palatine canals. 

Takingf the lateral reg-ion of the skull as a whole, it may be 
seen, from the foregfoing description, that it is triang-ular in 
outline and is bounded as follows ; the base is represented by 
the sweep of the temporal ridg-e ; the apex is at the ang-le of 
the inferior maxilla ; the sides may be represented by two lines, 
meeting- at the ang-le of the inferior maxilla, the one drawn 
from the external ang-le 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 ; part of the frontal bone ; part 
of the g-reater wing- of the sphenoid, part of the parietal, part 
of the malar, and the constituents of the spheno- maxillary 
fossa, as g-iven above. 

The Inferior Region of the Skull. 

The Inferior Reg-ion, 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 
process of the superior maxillary ; and from the tuberosity of 
the superior maxilla it is limited by an imaginary line, which, 
extending- by the styloid process of the temporal bone, passes 
back to the superior curved line of the occipital, and ends at 



90 DESCRIPTIVE ANATOMY. 

the posterior occipital protuberance. [In describiag" the appear- 
ances found on this face of the skull it is much more accurate 
to begfin with those on tlie mid-line of the body, which are sin- 
gle 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. 
Behind this foramen is the suture between the two horizontal 
plates of the two superior maxillary bones, and behind this 
again the suture between the two horizontal plates of the two 
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 fora- 
men magnum, beyond wdiich is found the vertical limb of the 
Occipital cross, which terminates in the posterior occipital pro- 
tuberance. On either side the following appearances will be 
noted : in front, the rough inferior surface of the palatine pro- 
cess of the superior maxilla, behind which lies the suture be- 
tween this process and the horizontal plate of the palate bones ; 
behind this the nasal cavity, and on the outer side of the nasal 
cavity, the pterygoid process and pterygoid fossa of the sphe- 
noid. Behind the pterygoid process is the middle lacerated 
foramen; external to that is the foramen ovale; external to 
this the foramen spinosum ; external to that the spine of the 
sphenoid ; and then the appearances seen on the inferior sur- 
face of the petrous portion of the temporal bone. The infe- 
rior surface of the petrous portion of the temporal exhibits as 
the most internal appearance a rough, quadrilateral projection 
of bone. Behind and external to this is the aperture of en- 
trance 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 laceriim posterius ; 
and in the interval between the posterior lacerated foramen 
and the carotid aperture of entrance is a thin sheet of bone 
marked by two minute apertures, the one for the transmission 
of Jacobson's and the other for the transmission of Arnold's 
nerve. The Vaginal process, as it passes upward and back- 



OSTEOLOGY. 91 

ward, divides to enclose the next appearance, which is the 
st3'loid process, while next to the styloid process is a foramen, 
the stylo-mastoid foramen. Still further behind is a narrow 
fissure between the vag-inal and mastoid processes called the 
Auricular Fissure, while internal to the mastoid process is 
another and larg-er depression, known as the Dig-astric 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 opening's of the posterior condyloid fora- 
miaa, when these foramina are present. In front on either 
side of the condyle is seen the anterior condyloid foramen. 
Behind these appearances is the roug-hened posterior surface 
of the occipital bone as far upas its superior curved line. 

In describing- the appearances on the base of the skull, it is 
necessary to g-ive not only those appearances, btit their bound- 
aries as well. Thus the tivo posterior nares are bounded, 
each internally by the posterior border of the vomer, externally 
by the inner surface of the internal plate of the pteryg-oid pro- 
cess, 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 basilar process of the occipital bone, extern- 
ally 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 g-reater 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. Pos- 
teriorly it is limited by the junction of the anterior border of 
the temporal with the basilar process of the occipital. To the 
outer side of the middle lacerated foramen can be distinctly 
seen the space between the squamous and petrous portions of 
the temporal, in which are lodged the two canals, the upper 
for the tensor tympani, the lower for the Kustachian tube, 
separated from each other by a thin process of bone, called the 
Processus Cochlcariformis (Iv. Cochleare, a spoon; forma, 



92 DESCRIPTIVE ANATOMY. 

shape). T\\Q, posterior lacerated foramen is bounded in front 
by the posterior border of the petrous portion of the temporal, 
and behind by the junction of the basilar process with the infe- 
rior border of the occipital, these two bones presentino- notches, 
which when articulated tog-ether 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 g"alli, 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 (Iv. A Turkish saddle), behind the 
sella turcica the Dorsum Ephif)pii (L. The back of a horse- 
cloth), behind that the Clivus BlumenbaclufLt. C/eV?^^", a slope), 
leading to the grooved upper surface of the basilar process of 
the occipital bone. Behind the Clivus Blumenbachii is the 
foramen mag-num, behind this the vertical limb of the occipi- 
tal 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 foss^. These are known as the 
anterior, middle and posterior ; and they descend like steps, 
the anterior being the highest, the middle next, and the poste- 
rior the lowest. '^\\Q^ anterior fossa oi 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 of which we have the posterior borders 
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 orbital ridge in the 
centre and the posterior border of the lesser wings of the 



OSTEOLOGY. 93 

Sphenoid laterally. Posteriorly it is bounded in the mid-line 
by the basilar suture, laterally by the upper border of the 
petrous portion of the temporal. The f)osterior 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 g-alli of the ethmoid, the upper surface of the lesser 
wing's 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 sur- 
face 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 
portion of the temporal, the postero-inferior ang-le of the 
parietal, and all of the anterior surface of the occipital which 
lies below the transverse g-roove for the lateral sinuses upon 
that bone. The appearances in the anterior fossa are the 
foramen caecum, the crista gfalli, the ethmoidal spine of the 
sphenoid and its articulation with the sphenoidal notch of the 
ethmoid and the optic ridg-e forming- one of its boundaries. On 
the mid-line of the frontal bone is seen the beg-inniug-of the long-i- 
tudinal sinus. The lateral appearances are the g-rooves which 
are found upon the upper surface of the cribriform plate of the 
ethmoid, including- the slits for the nasal nerves. Still further 
external is the irreg-ular upper surface of the orbital process of 
the frontal, three rows of foramina on the upper surface of the 
ethmoid, and the internal opening-s of the anterior and posterior 
ethmoidal foramina. In the middle fossa are seen the optic 
g-roove, the olivary process, and the sella turcica, with the 
dorsum ephippii upon the mid-line extending- to the basilar su- 
ture, forming- the line of separation between the middle and 
the posterior fossai. Laterally are seen in front the optic 



94 DESCRIPTIVE ANATOMY. 

foramina, the anterior clinoid process, behind and external to 
this along- the olivary ridg-e the middle clinoid process, ex- 
ternal to and slig-htly in front of this the anterior lacerated 
foramen, behind and external to that 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 external row of foramina is the italic- 
f-shaped g-roove for the carotid sinus, on the lateral aspect of 
the body of the sphenoid. 

Behind this is the upper opening of the middle lacerated fora- 
men, external to which are the appearances seen on the anterior 
face of the petrous portion of the temporal, presenting- from 
within outward the digital pit, the g-roove leading to the hiatus 
Fallopii, the petrosal g-roove, the bulge corresponding to the 
superior semi-circular canal, and the depression which corre- 
sponds to the tympanum and the orifice of the carotid canal. 
^\\Q. posterior fossa presents the inclined plane formed by the 
grooved upper surface of the occipital, the foramen mag-num, 
and the lower vertical limb of the occipital cross. lyaterally 
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, 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 commences at 
the jugular foramen on the jugular process o E 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 re-appears 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 into the 
condyloid foramina. Below the lateral limbs of the occipital 
cross are the fossae which lodg-e the cerebellum. 



OSTEOLOGY. 9o 



The Anterior Region of the Skull. 

The Anterior Region of the SkulU or Face, is bounded 
above by the supercfliary ridg-es, below by the basilar border 
of the inferior maxilla, and laterally by a line drawn from the 
external ang-ular process of the frontal bone throug-h the 
auo-le of the'inferior maxilla. It presents for examination 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 Nasal Cavity, presenting" its anterior aperture on the 
face, is bounded above by the lower end of the two nasal bones, 
on either side by the anterior border of the nasal process of 
the superior maxilla, below by the concave sharp free border 
of the horizontal or palate process of the superior maxilla. 
Internally each cavity is bounded by a triangular aperture, 
which in the recent subject is filled by a cartilag-e of similar 
shape, but which in the prepared skeleton shows only the an- 
terior border of the vomer and the anterior border of the per- 
pendicular lamella of the ethmoid. These cavities, when ex- 
amined from in front, exhibit two shelf-like projections, the 
inferior and middle turbinated bones. The inferior turbinated 
bone is a separate bone, while the middle is a projection 
from the lateral mass of the ethmoid. Between the inferior 
turbinated, which curls over in the cavity, and the upper sur- 
face of the palate process of the superior maxilla and the hori- 
zontal plate of the palate bone is a narrow long- opening, lead- 
in<,^ to the posterior nares, called the inferior meatus of the nose. 
Between the inferior and middle turbinated bones is a second 
canal of the same shape and character, thoug-h smaller in size, 
called the Middle Meatus of the Nose. The superior meatus. 
an opening- which lies between the superior and the middle 
turbinated bones, is smaller in size and more oblique in direc- 
tion than the inferior and middle. It is bounded above by the 
superior turbinated and below by the inferior turbinated bone , 



96 DESCRIPTIVE ANATOMY. 

hoth of them portions of the later:il miss of the ethmoid; and 
of course belong-s more especially to the ethmoid bone than to 
the cavity of the nose. The middle meatus communicates 
anteriorly by a tortuous canal, called the Iiifiindibulum , with 
the anterior ethmoidal cells, and with the sinuses of the frontal 
bone. It also opens into the antrum-maxillare. Posteriorly 
the superior meatus receives by the spheno-palatine foramen a 
communication with the spheno-maxillary fossa, while in- 
directly it extends through the pyramid of Wister, or sphe- 
noidal turbinated bone, into the posterior ethmoidal sinuses, 
and occasionally into the body of the sphenoid. The nasal 
cavities are more completely described among- the soft tissues. 
The Orbital Cavities. Kach 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, consequently a line drawn 
through the centre of each cavity would meet that of the oppo- 
site side over the middle of the sella turcica, passing through 
the optic foramina. The sides of these pyramidal cavities are 
superior, inferior, internal and external. The angles are su- 
pero-internal, supero-external, infero-internal and infero-ex- 
ternal. 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 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 ; behind that the superior surface of the 
orbital process of the palate bone articulating with the sphe- 
noid. The supero-external ang-le 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 bor- 
der of the anterior surface of the greater wing of the sphenoid, 
articulating with the orbital process of the frontal. The infero- 
internal angle is formed by the articulation of the lower ex- 



OSTEOLOGY. 97 

tremit}' 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 supe- 
rior maxilla; and behind that the maxillary surface of the orbi- 
tal process of the palate with the ang-le formed by the junction 
of the internal and superior surfaces of the superior maxilla. 
The infero-cxterual aiig-le is formed by the suture between 
the maxillar}^ process of the malar and the malar process of 
the superior maxilla, and behind these by the spheno-maxillary 
fissure. The superior xcall is formed entirely by the inferior 
surface of the orbital plate of the frontal. The external zjcill 
is formed jointly by the internal face of the orbital process of 
the malar, and the anterior surface of the g-reater 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 b}' the outer surface of the lachrymal, the outer 
face of the os planum of the ethmoid, and behind that 
by the orbital face of the orbital process of the palate 
bone. Kntering- into this cavity are two foramina, the 
anterior and posterior ethmoidal, which establish a means 
of communication between the anterior fossa? of the skull 
and the cavity of the orbit. Posteriorly, directly at its 
apex, enters the foramen opticiim, and below this is seen 
the anterior lacerated foramen, formed between the inferior 
border of the lesser wing" of the sphenoid and the posterior 
border of the outer surface of the greater wing-. This fora- 
men is triangular in outline, its apex directed upward and out- 
ward, and its base downward and inward, and communicates 
at an acute angle with a fissue 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, internally by the postero-external bor- 
der of the orbital face of the superior maxilla. Anteriorly it 

Des Anat— 7 



98 DESCRIPTIVE ANATOMY. 

is usually bounded b}^ the non articular portion of the poste- 
rior border of the orbital process of the malar ; but occasion- 
ally 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- between the posterior border 
of the orbital process of the malar and the external border of 
the anterior face of the sphenoid. Running" throug-h this wall 
are two minute foramina, transmitting* branches of the fifth 
nerve, called the tempero-nialar foramina. On the floor of 
the orbit, near its posterior extremity, is seenaslig-ht g-roove, 
which about the middle of the floor is converted into a foramen 
by plung-ing- beneath the orbital surface of the superior max- 
illa. This canal continues its course until it passes beneath 
the infraorbital margfin, and terminates on the anterior sur- 
face of the face. It is known as the infraorbital g-roove, in- 
fraorbital canal and infraorbital foramen in the three respec- 
tive places. On the roof of the orbit is seen near the internal 
ang"ular process of the frontal bone a sligfht projection or some- 
times a slig"ht depression, the Fovea Trochlearis. External 
to this is an aperture which passes throug'h above the marg^in 
of the orbit, and is known as the supraorbital foramen. 
I^xternal to this and just behind the external ang-ular process 
is the most depressed portion of the orbital cavity, forming- a 
fossa in which is lodg-ed the lachrymal g"land, the fossa being- 
known as the Fossa Lachrymalis. Below the orbit is the 
roug-hened projection of the malar process of the superior max- 
illa, while external to it are seen the external opening-s of the 
tempero-malar foramina. Below the inferior orbital foramen 
is a depression, called the Incisive Fossa. Above the orbits 
are seen the supraorbital ridg-es, and in the mid-line the nasal 
■prominence, or glabella. Below are the roug-hened surfaces 
of bone for the attachment of the various muscles of expression. 

The Nasal Fossae. 

The nasal fosss are two irreg-ular cavities situated in the 
face and extending- from the anterior to the posterior nares. 
The septum between the two is formed, above, by the perpen- 
dicular lamella of the ethmoid bone, in its lower posterior part, 



OSTEOLOGY. 99 

bs^ the vomer and the ang-ular interval left between the two, in 
front, is filled in by a triang-ular plate of fibro-cartilag-e, called 
the cartilag-e of the septum. Each fossa presents for exami- 
nation /'o/^r zualls. The inner wall is formed by the septum. 
The outer zvall is formed by the superiormaxiUa, t\\.Q inferior 
turbinated, the lachrymal, the ethmoid, the palate and the 
internal pterygoid plate oi VclQ. sphenoid. The roof 'vs> formed 
by the nasal, the frontal, the ethmoid and the body of the 
sphenoid. The /f cor is formed \r\. front, by Wi<i palate process 
of the superior maxilla and completed behind hy the horizontal 
plate of ihQ palate bone. The outer wall of the nasal fossa is 
very uneven; a considerable bulg-e inward is produced, throug-h- 
out its whole length, by the inferior turbinated bone, and the 
space between this bone and the floor is called the inferior 
meatus. Above the inferior is the middle turbinated bone, a 
part of the lateral mass of the ethmoid, and the space between 
these two is known as the middle meatus. In the upper part of 
the inner face of the lateral mass of the ethmoid, is a fissure called 
the superior meatus, situated between the superior and middle 
turbinated bones of the ethmoid. Opening- into each fossa are 
eight apertures. Into the superior meatus there are three 
openings: 1st, the opening of the sphenoidal cells; 2d, the 
opening from the posterior ethmoidal cells; 3d, the spheno- 
palatine foramen, communicating with the spheno-maxillary 
fossa. In the middle meatus there are also three openings: 1st, 
the opening into the antrum viaxillare ; 2d, the opening into the 
a)iterior ethmoidal c^Ws,; 3d, the opening from \h^frontal sinus ; 
the last two communicating with the upper front part of the 
meatus through the infuulibulum. Into the inferior meatus 
there are two openings; 1st, the nasal duct, on its outer wall, 
and 2d, the anterior palatine foramen, on the floor. Just 
pfjsterior to the outer wall of the inferior meatus is the opening 
of the Eustachiaii tube, in fresh subject. 

Articulation of the Bones of the Skull — Occipital Bone. 

The occipital bone articulates by its txvo condyles with the 
Atlas; by its superior border with the tzuo parietal bones, 
forming the lambdoid suture, by the outer half of each inferior 



100 DESCRIPTIVE ANATOMY. 

border with the posterior border of the rtiastoid portion of the 
temporal 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. 

Parietal Bone. 

The parietal bone articulates by its u-p-per border with its 
fellow, forming the sag-ittal suture; by its lozoer border with 
the upper part of the semicircular border of the squamous 
portion of the temporal bone, forming- the squamous suture; by 
li^ posterior border with the upper border of the occipital; by its 
anterior border, with one-half of the semicircular border of 
the frontal, forming- one-half of the coronal suture; by its ante- 
rior inferior angle, with the frontal triang-le of the sphenoid, 
i. e. , 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 semicircular 
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 triang-ular surface 
i. e., the sphenoidal triang-le of the frontal, at the junc- 
tion of the straig-ht and semicircular borders, with the 
upper border of the outer surface of the g"reater wing* of 
the sphenoid; by the circumference of the ethmoinal fissure 
with the lateral and anterior borders of the cribriform plate 
of the ethmoid, and with the upper surface of the lateral mass 
of the ethmoid; 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 w^ith the 
lachrymal bone; by the external ang-ular process with the 
frontal process of the malar bone, and by the part just behind 
this with the orbital process of the malar. 



OSTEOLOGY. 101 

Temporal Bone. 

Squamous Portion. 

The squamous portion articulates by the upper part of its 

semicircular border with the lower border of the parietal bone; 

by the front part of the same border with the posterior border 

of the outer surface of the greater wnng- of the sphenoid ; by 

the lower part of the same border wdth the outer part of the 

posterior border of the upper surface of the g-reater wing- of 

the sphenoid : by the anterior part of the glenoid fossa wnth 

the condyle of the inferior maxilla ; by the extremity of the 

zygomatic 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 posterior border with 
the inner half of the lower border of the occipital bone; by its 
anterior border with the middle part of the posterior border 
of the upper surface of the greater wing of the sphenoid. 

Sphenoid Bone. 

Body: By Wv^ posterior surface oi the body with the basilar 
process of the occipital; by the ethmoidal sfine with the 
sphenoidal notch of the cribriform plate of the ethmoid; by 
the crest with the upper part of the posterior border of the 
perpendicular 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 sur- 
face of the orbital and upper surface of the sphenoidal process 
of the palate bone; by the rostrum and vaginal prrcesses with 
the upper border of the vomer. 

Greater Wing. By the posterior border oi its upper sur- 
face with a portion of the anterior border of the petrous por- 



102 DESCRIPTIVE ANATONY. 

tion of the temporal; by the external border oi the superior sur- 
face (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 ang-le of the parietal, and with the outer part of the 
sphenoidal triang-le of the frontal; by the anterior border oi 
the outer face with the posterior border of the orbital process 
of the malar; by the outer -part of the upper border of the 
orbital face with the straig-ht border of the frontal bone; by 
Vae. frojital triang-le lying" just internal to the upper border of 
the outer surface with the sphenoidal triang-le 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 poste- 
rior border of the perpendicular plate of the palate; by the 
triangnlar 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. 

Ethmoid Bone. 

Horizontal Plate: By its lateral and anterior borders with 
the circumference of the ethmoidal fissure of the frontal. By 
crista galli with anterior border of ethmoidal notch forming* 
foramen coecum. By the spheniod notch with the ethmoidal 
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 
\\j& 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 ante- 
rior 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,throug"h 
the medium of the pyramid of Wistar ; by its anterior extreme 



OSTEOLOGY. 103 

ity 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 horizontal plate, 
by the lower border of the os planum with the inner border 
of the orbital face of the superior maxillary bone, and behind 
that with the orbital process of the palate bone ; by the pos- 
terior border of the os plamim 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 anterior extremity of the 
middle turbinated bone with the superior turbinated crest of 
the nasal process of the superior maxillary ; by the poste- 
rior extremity oi 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 ; bv its outer border with the nasal process of the supe- 
rior maxillary ; by its inner border with its fellow ; by the 
crest oi the two bones, above, with the nasal spine of the fron- 
tal ; 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 
brjrder 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 sinus with the anterior border, the max- 
illary process and most of the outer surface of the vertical 



104 DESCRIPTIVE ANATOMY. 

plate of the palate; above the aperture with the outer surface 
of the lateral mass of the ethmoid, below the os planum; be- 
low the aperture with the maxillary process of the inferior 
turbinated bone ; in front of the aperture with the projection 
on the anterior border of the lachrymal and the lachrymal 
process of the inferior turbinated ; by the injerior turbinated 
crest with the anterior extremity 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 bordeo with the anterior border of the horizontal 
plate of the palate. 

Nasal Process : By its upper border with the nasal notch 
and internal ang-ular process of the frontal; by the inner ed^e 
of its posterior border with the anterior border of the lach- 
rymal 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 P/«/^ 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 bor- 
der 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 in- 
ner face of the body of the superior maxillary, behind the ap- 
erture into the antrum; by its superior turbinated crest ^NWh. 
the posterior extremity of the middle turbinated bone; by its 
inferior turbinated crest with the posterior extremity of the 
inferior turbinated bone; by \t^ posterior border with the ante- 



OSTEOLOGY. 105 

rior border of the pteryg-oid process of the sphenoid; by the 
<niterior face of the tuberosity with the lower part of the 
posterior border of the body of the superior maxillary and by 
its posterior face with the lower part of the anterior edgfe of the 
two pterygoid plates filling in the gap between them; by the 
anterior face of its orbital process with the posterior part of 
the internal border of the orbital face of the body of the supe- 
rior 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 fice with the front of the body of 
the sphenoid, through the pyramid of Wista. By the upper 
surface of the sp\\e)widal process with the lower surface of 
the vaginal process of the sphenoid ; by its posterior border 
and the posterior part 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 alec with the opposing faces of the vaginal 
process and lower surface of the body of the sphenoid; by its 
louer border, posteriorly, with the crested inner border of 
the horizontal plate of the palate and anteriorly with the 
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 wnth 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 pro- 
cess with the lower margin of the aperture of the antrum ; by 
the ethnioidal process with the unciform process of the ethmoid. 



106 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 lozuer 
extremity with the front part of the internal border of the or- 
bital plate of the superior maxillary; by the anterior border 
with the inner edg'e of the posterior border of the nasal pro- 
cess of the superior maxillary and by the projection from the 
lower end of this border with the edg^es of the lachrymal sul- 
cus 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 internul surface with the anterior 
extremity of the lateral mass of the ethmoid. 

Malar Bone. 

The 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 maxillary. 

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 Zyg-omatic Process w^ith the zygomatic process of the 
temporal bone. 

By the Orbital Process ; the lozver Z^oro'^r articulates with 
the orbital surface of the superior maxillary, antero-externally; 
by the posterior border, with the outer border of the orbital 
plate of the greater wing of the sphenoid; and by the iipper 
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. 

The Hyoid Bone. 

The hyoid bone, or lingual bone is placed in the upper, 
front part of the neck atthe bis2 of the tongue. It isU shaped 



OSTEOLOGY. 107 

and lies horiz;ontally, being- a symmetrical bone. It is an 
isolated bone, but is connected by aligfamentous cord, on either 
side, with the styloid process of the temporal bone; occasion- 
ally this cord becomes ossified and then a complete bony arch 
is formed between the two temporal bones throuo-h the hyoid 
bone. It is divided for study into a body and four cornua, or 
projections. The body presents two surfaces, two borders, 
and two extremities. The anterior surface looks upward and 
slig-htly forward and presents four depressions, separated by 
a crucial ridge; the confluence of the arms of the ridg-e produc- 
ing- a prominence called the tubercle. The posterior face looks 
downwards and slig-htly backwards; is concave, both trans- 
versely and vertically, presenting- a deep concavity. The upper 
border faces backward and is rounded and roug-h. The lower 
border faces forward, is protuberant and marked by musclular 
attachment. The extremity is oval and roug-hened by cartil- 
ag-inous attachment. The g-reater cornu stands backwards 
from the extremity of the body, on either side, and is rounded, 
g-rows smaller, but is terminated posteriorly by a nodular en- 
larg-ement. It is slig-htl}^ flattened vertically. 

The lesser cornu is, until old ag-e, cartilag-inous; it is a mere 
nodule of cartilag-e, hook like and about a quarter of inch long-; 
its direction is upward, backward and slig'htly outward and 
it articulates by a diminutive joint at the junction of the bodv, 
and g-reater cornu. It becomes calcified and its joint obliterated 
only very late in life. 



108 DESCRIPTIVE ANATOMY. 



THE LIGAMENTS. 

The study of joints, or articulations, is the study of the re- 
lation between bones, more particularly of the surfaces of ap- 
position and the means by which the bones are held tog"ether 
and at the same time permitted to move upon one another. In 
the study of osteology it has been seen that the articular sur- 
faces of the different bones present widely varying" appear- 
ances ; 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 immovable joint. This form of articulation is 
called synarthrosis. 

The contiguous surfaces may be roughened, showing the 
attachment 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 indi" 
cates a joint in which motion is very slight, consisting of a 
twisting of the ligimentous 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, Synarthrodial, 
or immovable joints ; 2nd, Amphiarthrodial, or partially mov- 
able ; and 3rd, Diarthrodial, or freely movable joints. 

Besides the bones, there are other structures which contri- 
bute 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 interosse- 
ous ligaments. In the Diarthrodial joints, as a rule, no liga- 
mentous fibres are attached to the articulating surfaces of the 
bones ; the ligaments, more or less completely surrounding- 



LIGAMENTS. 109 

the joint, are attached to both bones beyond the articular sur- 
faces. The fibres may entirely surround the joint forming- a 
capsular lig-ament, or they may be g-athered into separate bun- 
dles. 

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 
awa3% or becomes inconspicuous. 

If joints are subject to very frequent motion, the effect of 
friction is further g-uarded ag-ainst by a plate of fibro-cartilage, 
called the interarticular cartilag-e. This is a more or less flat, 
circular plate of cartilage interposed between the encrusting- 
cartilages of the bony surfaces, and attached only by its cir- 
cumference to the lig*aments. When this exists entire, the 
joint will have two synovial membranes, but occasionally the 
plate is \vorn throug-h and then, the two membranes communi- 
cating-, there is virtually but one. 

Synarthrodia! Joints — 4 Kinds. 

The immovable joints are almost confined to the bones of 
the skull, the articulations between which are g-enerally called 
sutures. 

There are several varieties of suture : 1st. Dentate, or Ser- 
rate, 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 roug-hened surfaces come in contact, as the 
inner border of the palate processes of the two superior max- 
illary bones. 3d. Schindylesis, where the edg-e of one bone is 
received in a groove in another, as the articulation between 
the vomer and the sphenoid. 4th. Gomphosis, where a bone 



110 DESCRIPTIVE ANATOMY. 

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. 

DiartKrodial Joints — 6 Kinds. 

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. 

2nd. Hing-eor trochlear, or cringlymoid, characterized by the 
presence of a pully 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 generally capable 
of very free movement. 

4th. Saddle-shaped, or concavo-convex joints, or joints of 
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. The}" present an osseo-ligament- 
ous 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. Bill and socket, or enarthrodial joints. — These present 
a more or less spherical head, as one contribution, while a re- 
ceiving cavitj' is the other. The two important examples of 
this variety are the shoulder and hip, in both of w^hich motion 
is very free. 

In describing a joint, the following heads have to be consid- 
ered : 

1st. The class and variet\^ 2nd. The bony contributions. 
3rd. The ligaments. 4th. The synovial membrane. 5th. 
The inter-articular cartilage, perhaps. 6th. The motions of 
v,'hich the joint is capable. 7th. The muscles which 
strengthen the joint, if an5^ 



LIGAMENTS. Ill 

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 peculiarls* characteristc of the arthrodial. It 
consists of the slippiag* of one, m^ri or less, flit an.i plane 
surface on another. 

(d) Flexion — anovular movement of a segfrnent of the body 
in an antero-pDsterior 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 a'J-ain to flexion. In outward circum- 
duction the order is reversed. In the performance of this 
movement, the moving segment circumscribes a coneshaped 
space, the apex of which is at the joint and the base at the 
distal extremity of the moving segment. 

(^) 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. 

(/^) Rotation, or true rotation. This is almost limited to 
two joints, the shoulder and the hip, and, as it happens, can 
be defined in the same terms for both, viz : movement outward 
or inward around a line drawn from the innerm3st point of 
the humerus or femur, to the innermost point of the inner 
condyle of either bone. 

6th. A statement of the mechanism of motion — that is, of 
the changes which occur in the relative positions of the artic- 
ulating surfaces during the performance of any given motion, 

7th, The muscles which are in contact with the ligaments 
of the joint, and which may be considered as imparting 
strength to the articulation. 



112 DESCRIPTIVE ANATOMY. 

8th. In the important joints, the arteries and nerves distri- 
buted to them. 

The Articulations of the Vertebral Column. 

The articulations of the spinal column may be divided intO' 
those of the (1st) Column in g-eneral; (2d) Atlo-axoid; (3d) 
Occipito-atloid; (4) Sacro- vertebral. 

Articulations of the Spine in General. 

E)ac-h 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 
articular processes. The lig-aments are capsular around the 
articulating- surfaces, and those which bind the same seg-- 
ments of the different vertebrae tog-ether. These ligaments 
are collectively known as the common lig-aments of the spine. 

Articulation of the Articular Processes. 

The articulation between contig-uous articular processes is a 
diarthrodial joint of the arthrodial variety, presenting- a 
synovial membrane and one ligament, an imperfect capsular 
ligament. 

The Ligaments of the Spine in General — Ligaments of the 

Bodies. 

The bodies of the vertebrae are connected by means of 
intervertebral disks and anterior and posterior common lig-a- 
ments. The intervertebral disk is found lying- between the 
opposing* surfaces of two adjacent vertebrae, firmly adherent 
to each. In shape it corresponds exactly with the bodies be- 
tween which it lies; in thickness it varies with the different 
reg-ions 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 con- 
centric 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 
vertebra below to the lower surface of the vertebra above; and 



LIGAMENTS. 113 

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 ma}" twist or untwist as the occasion demands. 

The Anterior Common Ligament is found descending- along- 
the front of the bodies from the axis to the sacrum, widening- 
as it descends. As a matter of fact this ligament extends to 
the basilar process of the occipital bone; but it has been custo- 
mary to consider the upper portion extending- from the axis 
to the occipital bone as a separate lig-ament. It is composed 
of superimposed la3^ers of fibres, the deepest of which are at- 
tached simply to the bodies of adjacent vertebrae, while the 
next layer of fibres extends over two or three vertebrae, and 
the most superficial extends over four or five. This liga- 
ment w^idens as it descends, is not attached over the centres 
of the bodies of the vertebrae, where it leaves a slig-ht space 
between 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 Common Lig-ament lies within the spinal 
canal ; and is attached to the bodies of the vertebrae, extend- 
ing- from the axis to the sacrum. Just as is the case with the 
anterior common ligament, this in reality extends to the cra- 
nium ; 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 lig-ament it narrows as it descends ; and instead 
of having- straig-ht edg-es, it is scalloped, widening- over each 
intervertebral disk and narrowing- over the body. It is thinner 
and less powerful than is the anterior common lig-ament. 

Ligaments of the Laminae. 

The ligaments that binds the laminae together consist of 
yellow ligamentous fibres, called the ligamenta subjlava. 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 

Des Anat— 8 



114 DESCRIPTIVE ANATOMY. 

the laminae. They are thicker iu the loins than in the back 
and neck, and the thickest portion corresponds to the position 
of the spinous process. 

Ligaments of the Spinous Processes. 

The spinous processes are connected by two lig-ameuts, the 
s lipjri Rnd intersf>inous. 'Vhe sup7'aspi>io2is 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- 
tinued upward by a more prominent band, which has received 
the name of the lig-cunentum nuchae (L. nucha, a nape). This, 
in man, is composed almost entirely of fibrous tissue, and is 
simply a division of the supraspinous lig^ament. The inter- 
s-pinous lig-ament consists of thin fibres, which are attached to 
the adjacent edg-es 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 trans- 
verse processes held together by a few scattered intermediate 
fibres, called intertransverse ligaments, extending between the 
adjacent 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 processes, as seen between other vertebrse, 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. 

The anterior atlo-axoid ligament, usually described as two, 
consists of a broad band of ligamentus 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 



LIGAMENTS. 115 

is described as a separate lio-ament. It is merely a continua- 
tion of the anterior common lig-ament of the spine. 

The posterior atlo-axoid li^^ament is a membrane-like fold 
closing" in the space between the vertebrse behind. It is attached 
above to the posterior surface and lower border of the posterior 
arch, extending- from the capsular lig-ament of one side to that 
of the other and blending- with the capsules. Below it seizes 
the laminae of the axis. 

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. As it passes over the odontoid 
process a vertical band of fibres crosses it, some of them de- 
rived from the transverse lig-ament, 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 g-ives the lig-ament the 
form of a cross, hence its name, crucial lig-ament. 

The two capsular ligaments are attached around the mar- 
gins of the articular facets on the two vertebrae, blending- 
with the posterior atlo-axoid lig-ament. 

There are four synoval sacs connected with the articulation. 
Two belong- to the joints formed by the articular processes, 
one is interposed between the front of the ondontoid process 
and the facet on the anterior arch of the atlas, while one inter- 
poses between the posterior face of the odontoid process and 
the front of the transverse lig-ament. 

The Occipito-Atloid Articulation. 

This is a movable joint of the condyloid variety, the articu- 
lating- surfaces being- the two condyles of the occipital above 
and the superior articular facets of the atlas below. The lig-a- 
ments, seven in number, are 

Two anterior occipito-atloid Posterior occipito-atloid 

Two Lateral Occipito-Atloid Two capsular. 

The central part of the anterior occipito-atloid ligament 
is a rounded cord attached below to the tubercle on the ante- 



116 DESCRIPTIVE ANATONY. 

rior arch of the atlas and above to the under face of the basi- 
lar process of the occipital. It is the upward continuation of 
the anterior atlo-axoid, and through it of the anterior common 
ligament of the spine. The lateral portion of the ligament is 
a broad and thin band attached above to the margin of the 
foramen magnum and below to the anterior arch of the atlas, 
extending to the beginning of the capsular ligaments, with 
which it blends. 

The jyosterior occipito-atloid is a broad and thin membra- 
nous band attached above around the margins of the foramen 
magnum and below to the upper border and posterior surface 
of the posterior arch of the atlas. It corresponds to the liga- 
ments 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 be- 
low. 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 lig-anient is a broad membranous band 
which continues the posterior common ligament of the spine 
upward to the occipital. It is attached belov/ by some fibres 
to the body of the third cervical vertebra and to the body of 
the axis. Passing upward it covers over the odontoid process 
and the crucial ligament and is attached to the anterior margin 
of the foramen magnum, passing upon the basilar process to 
blend with the dura. 

The odontoid or check liga?7ient con'^i^i^ 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. 



LIGAMENTS. 117 

The vertebral artery supplies both of these articulations. 
The loop between the first and second cervical nerves supplies 
the articulation between the axis and the atlas, while the sub- 
occipital supplies the occipito-atloid articulation. 
Sacro- Vertebral Articulation. 

The joint between the sacrum and last lumbar vertebra, is 
similar to that between two vertebrae, the articulating- sur- 
faces 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-hunbar and 
himbo-sacral, which are generally considered among the liga- 
ments of the pelvis. The ilio-lumbar extends from the trans- 
verse process of the fifth lumbar vertebra outward to the 
ilium just above and in front of the ear-shaped articular sur- 
face. The lumbo-sacral passes from the transverse process 
of the fifth lumbar vertebra downward and outward to the 
wing of the sacrum. 

Movemoits. 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 
condyles of the occipital glide backward and forward on the 
articular surfaces of the atlas. Thus, in flexion the chin is 
carried to the chest while the condyles pass backward 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 con- 
dyle of that side passes inward while the one of the opposite 
side passes outward in the corresponding cavity. Motion be- 
tween 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 inferior facet of the atlas of the side to which motion is 
made, glides backward on the axis and the opposite facet glides 
forward. 

Moveynents of the spine as a whole. The amount of motion 
which may take place between any two contiguous vertebrae 



118 DESCRIPTIVE ANATOMY. 

is but slight, yet the column as a whole enjoys a wide rang-e 
as well as a great variety of movements. These movements 
are the four ang-ular movements, flexion, bending- forward, 
extension, bending* backward, and rig-ht and left lateral move- 
ment. In addition to these a considerable amount of rotation, 
by twisting" of the lig-amentous fibres is permitted. In flexion 
the body bends forward, compressing* the anterior fibres of 
the intervertebral 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 interspinous and the sub-flava ligaments are all 
stretched. The superior articular processes g-lide upward on 
the inferior in this movement. Flexion and extension are both 
free in the cervical and lumbar regions, the vertical direction 
of the articular processes limiting the movement in the dorsal. 
Lateral flexion is most free in the cervical region, the inver- 
sion of the superior articular processes limiting it in the lum- 
bar, 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. Rotation 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 supe- 
rior 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 



LIGAMENTS. 119 

articular surface on the inner extremity of the clavicle, which 
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 b}'' a concavity 
on the cartilaufe of the first rib. The following- ligaments 
bind the bones together : 

Capsular Romboid, or Costo-Clavicular 

Interclavicular Inter-articular fibro-cartilage. 

The inter-articular fihro-cartilag-c is attached 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 manu- 
brium. It serves the double purpose of holding the bones 
together and at the same time divides the joint into two syno- 
vial cavities. 

The ca-psnlar lig-ameiit is a thick band of fibres completely 
surrounding the tjoint but thicker at some points than at 
others. Thus it is seen to be much more thickened behind than 
elsewhere, being sometimes described as the posterior liga- 
ment of the joint. In front it blends with the tendon of the 
sterno-mastoid muscle, above with the interclavicular ligament 
while below it is continuous with the Romboid. The deepest 
fibres of this ligament pass from the two bones to the interar- 
ticular 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 margfin 
of the articular surface on the clavicle. 

The interclavicular linanieut is a strong thick band attached 
to the upp_'r an 1 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 roniljoid^ or cosio-clavicular ligament is a set of short 
fibres resembling fibro cartilage which extend from the rom- 
boid impression of the clavicle downward, forward and inward 
to be attached to the upper face of the cartilage of the first rib. 



120 DESCRIPTIVE ANATOMY. 

There are two synovial membranes, one interposed between 
the cartilag-e and the manubrium and the other between the 
inner extremity of the clavicle and the cartilag-e. In some cases 
the cartilag-e is worn throug-h and the synovial sacs communi- 
cate with each other, practically forming- one sac. 

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 rang-e and are always of 
a g-liding- 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 
interarticular cartilag-e, passes forward; in forward movement 
of the shoulder, the clavicle passes backward; in upward move- 
ment of the shoulder the clavicle passes downward; but in 
downward movement of the shoulder, the clavicle passes up- 
ward, putting- the fibres of the cartilag-e on the stretch and 
limiting- the extent of the movement. 

Scapulo-Ciavicular Articulation. 

This is a movable joint of the arthrodial variety. The ar- 
ticulating- surfaces are an oval facet on the outer extremity of 
the clavicle and a corresponding- facet on the anterior edg-e of 
the acromion process of the scapula. It must be observed that 
the clavicle, in its outward course, passes just above the cora^ 
coid process of the scapula, and, while it does not articulate 
with it, receives a lig-ament from it. 

The bones are held tog-ether by two sets of lig-aments, a 
capsular, surrounding- the articular surfaces, and acoraco-clavi- 
cular binding- the clavicle to the coracoid process. 

The caf>sular ligament is a strong- but lax band of fibres 
surrounding- the joint and attached to the clavicle beyond the 
articular facet. Inferiorly these fibres pass as far as the 
coraco clavicular lig-ament with which they blend. Above, 
they are streng-thened by fibres of the deltoid and trapezius. 

The coraco-clavicular consists of two portions, the conoid 
and the trapezoid. The conoid lig-ament is triang-ular in form 



LIGAMENTS. 121 

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 surface looking- for- 
ward and backward. Below it is attached to a rido-e on the 
upper aspect of the coracoid process, while above it is attached 
to the oblique ridg-e running- forward and outward from the 
conoid tubercle to the anterior border of the clavicle. 

This joint has an interarticular fibro cartilag-e, which, how- 
ever, is often absent. When this is present there are two 
S3'novial sacs, otherwise, but one. 

The -joint is supplied by the acromial thoracic and supra- 
scapular arteries and by the circumflex and suprascapular 
nerves. 

The movenioits of the joint are confined to a slight g-liding- 
of the articular surfaces upDn one another. Usually the 
scapula is the bone which moves; but, of course, when the 
scapula is fixed, the clavicle may gflide upward, downw^ard 
backward or forward. 

Ligaments of the Scapula. 

Stretched between different points on the scapula are two 
ligaments, coraco-acromial and transverse. The coraco-acro- 
viial, thick and triang-ular, 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 ex- 
tremity to the other, converting^ it into a foramen. 

The Shoulder Joint. 

The shoulder is a joint of the diarthrodial class and enar- 
throdial or ball and socket variety. The bones entering- into its 
formation are the upper extremity of the humerus, with its 
g-lobular head, anatomical neck and two tuberosities ; and the 
g-lenoid cavity of the scapula, supported b}' its neck and over- 
hung- by the c(;racoid and acromion processes. The lig-aments 
of the joint are properly but two, the g-lenoid and capsular, 
thoug-h some accessory bands of the latter are frequently dig-- 



122 DESCRIPTIVE ANATOMY. 

nified as separate ligaments. The g-lenoid lio-ament is a band 
of fibro cartilag-e, 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 ligameat. 

The caps2ilar lig-ctment 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 artic- 
ular 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 trans- 
verse band which binds the tendon of the biceps in its groove. 
Inferiorly it is prolonged over the surgical neck of the humer- 
us to a slight extent. The upper part is very much thicker 
than any other portion of the ligament. 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. The capsule is nearly surroun- 
ded by muscles whose tendons, as they pass over it,are blended 
with the ligament and supply the greater part of its strength. 

The synovial meinhrane is extensive. It lines the interior 
of the capsule and is reflected over the margins of the articular 
surfaces, but does not reach the p.jints 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 subscapularis muscle and frequently with 
one beneath the infraspinatus. 

The joint is powerfully reinforced and protected not only 
by the numerous muscles which surround it but also by a pro- 
tecting arch formed by the acromion and coracoid processes and 



LIGAMENTS. 123 

the coraco-acromial lig-ament stretched between them. The 
muscles are, above the supra spinatus, postero-superiorly the 
infraspinatus and teres minor, antero-internally the subscapu- 
laris : 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. 

The arterial supply is chiefly from the anterior and posterior 
circumflex, but branches are derived from the dorsalis scapula? 
and suprascapular arteries. The nerves are the suprascapular 
and circumflex. 

Movements and mechanism. The leng-th of the capsular 
lig"ament, the shallowness of the receiving* cavity and the com- 
paratively larg-e size of the humeral head, permit this joint to 
enjoy a gfreater variety and extent of movement than au}^ 
other in the body. Like all enarthrodial joints it is capable 
of the four ang-ular movements, their combination, circum- 
duction, 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 head throug-h the centre of 
the g"reater tuberosity, to the centre of the g"lenoid cavity. In 
extension the reverse movement takes place, with of course a 
reversal of the mechanism. In abduction the humerus is 
carried away from the mid-line of the body, the hand raised 
toward the shoulder, while the head of the humerus g-lides 
downward in the g-lenoid cavity until it presses on the inferior 
fibres of the capsular lig-ament. When the humerus is carried 
in abduction to arig-ht angle with the body, further movement 
is arrested by the impact of the bone against the arch of the 
acromion, further movement in this direction being- effected by 
the g-liding- 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 combina- 
tion 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 



124 DESCRIPTIVE ANATOMY. 

around an axis drawn from the centre of the head downward 
throug-h the internal condyle, the head moving- backward in 
inward and forward in outward 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 
marg-in of the gflenoid cavity, where it is blended with the 
g-lenoid lig-ament, it passes across the upper outer aspect of 
the joint, pierces its capsular lig-ament and is covered by a 
prolong-ation of the synovial membrane which lines the cavity. 
This tendon, therefore, becomes a powerful ag-ent in retaining- 
the head of the humerus in apposition with the g-leniod 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- 
separated by the interosseous space throughout the shafts. 

The lig-aments holding- the bones tog-ether are found at their 
npp^r 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. The ligament surrounds 
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 radius just below the 
head, rendering it very difficult to release that bone from its 
grasp. 

The shafts are connected b}^ two ligaments, the interosseous 
and the oblique. The oblique 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 extends from the lower extrem- 
ities of the bones upward about two-thirds the length of the 
shafts, leaving an interval, above which is 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 



LIGAMENTS. 125 

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 togfether by 
two lig-aments and the trtanfj;-ular fibro-cartilag-e. The two 
lig^aments are an anterior and a posterior passing- across the two 
bones. The triangfular cartilag-e tips the summit of the capi- 
tulum ulnae; and excludes it from the wrist joint. Bv its apex 
it is attached to the pit between the styloid processof the ulna 
and the capitulum ulnae; by its base to the narrow roug-h sur- 
face separating- the carpal and sigmoid cavities of the 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 
of the radius throug-h the centre of the capitulum ulnae; conse- 
quently in performing- pronation the sig-moid 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 lig-ament. 

The Elbow. 

This is a diarthrodial joint of the g-iug-lymoid variet3\ The 
bones entering- into its formation are the trochlear surface and 
the rounded eminentia capatata on the lower extremity, of the 
humerus, and the g-reater sig-moid cavity of the ulna with the cup- 
shaped upper extremity of the radius. The shape of the articu- 
lar surfaces furnished by the radius and humerus would 
render this joint one of the enarthrodial variety ; but the 
movements are so restricted by the close lig-amentous union 
^-between the ulna and radius, that the joint presents but one 
of the peculiar movements of the enarthrodial joints — rotation. 

The lig-aments are anterior and posterior, internal and 
external lateral. There, as always, some thin fibres which 
connect the various parts of the lig-amentous bands tog-ether, 
completing- the capsule around the joint. 

The anlerior lig-aDieiit is attached above to the humerus just 
above the coranoid fossa, while below it seizes the lower sur- 
face of the coranoid process and the orbicular ligament. 



126 DESCRIPTIVE ANATOMY. 

^\\Q, f)Osterior lig-aments is attached above to the humerus 
just above the olecranon fossa and below to the g-roove 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 is attached above to a depres- 
sion beneath the external condyle while its base is attached to 
the orbicular lig-ament. 

The internal lateral is attached above to the internal con- 
dyle while below it expands into two fasciculi with a triang-ular 
interval, filled with thin fibres, between 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 internal condyle, is below 
attached to that margin of the sigmoid cavity furnished by the 
olecranon process. By means of a few thin, scattered fibres, 
the lateral ligaments are connected with the anterior and pos- 
terior ligaments, thus completing an imperfect capsule. 

The synovial membrane is extensive. It lines the whole of 
the inner face of the capsule, extending upward behind to the 
olecranon and in front to the coranoid fossa ; while below it 
covers the interior of the orbicular ligament and furnishes the 
lining for the articulation at the superior radio ulnar articula- 
tion. 

The muscles which strengthen the joint are in front the 
brachialis anticus, behind the triceps and anconeus, externally 
the muscles arising from the external condyle, notably the 
supinator brevis ; and internally those which arise from the 
internal condyle. 

The move7Jients 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 
movement being arrested when the coranoid process impinges 
upon the coronoid fossa. In extension the reverse would occur 
and the movement would be arrested by the impact of the beak 



LIGAMENTS. 127 

of the olecranon on the bottom of the olecranon fossa. The 
movement of the radius will be described with the radio-ulnar 
articulation. 

The arterial supply of this joint is derived from communi- 
catinof branches between the anastoraotica mag-na, 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 Wrist Joint. 

This is a diarthrodial joint of the condyloid variety. The 
receiving- cavity, oval, transversely, concave both from before 
backward and from side to side, is furnished by the lower ex- 
tremity of the radius, aided by the triang-ular cartilag-e which 
shuts out the ulna from participation in the joint. The con- 
dyle is provided by three of the bones of the first row of the 
carpus, scaphoid, semilunar and cuneiform. The ligaments 
anterior, posterior and two lateral. 

All lig-aments of this joint blend with the ligaments of the 
carpus and can with difficulty be separated from them. Thus 
the anlcrior ligament is attached above to the margin of the 
carpal cavity of the radius and to the anterior radio-ulnar liga- 
ment, 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 palmer ligamentous 
fibres which bind together the first and second rows. The 
fiosterior is, in like manner, attached above to the posterior 
margin of the carpal cavity and to the posterior radio-ulna 
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 lig-amcnt 
is attached above to the styloid process of the radius and be- 
low to the tuberosity of the scaphoid and to the trapezium. 
The internal lateral liij;-ament is attached above to the styloid 
process of the ulna, below to the inner side of the cuneiform 
and unciform, to the latter through the medium of the internal 



128 DESCRIPTIVE ANATOMY. 

lateral ligament of the carpus. Between these bands are fibres 
which convert this lig-ament into a capsule. 

The synovial membrane lines the interior of the ligament- 
ous fibres and to a slight extent dips ia between the scaphoid 
and semilunar and between the semilunar and cuneiform. 
There are no muscles which directly strengthen the joint. 
Many tendons pass over it but their laxity prevents their add- 
ing 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 tendons, also, by the tonic con- 
traction of the muscles, aid in retaining the bones in apposi- 
tion. 

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 ex- 
tremity 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. E)xagger%ted 
movement as from a fall on the flexed hand, would produce 
dislocation. In .extension the mechanism is the reverse of 
flexion. In adduction the hand is carried toward the mid line 
of body while the condyle passes outward, the movement be- 
ing limited by the external lateral ligament. In abduction the 
reverse is true. The combination of these movements make^^ 
circumduction, 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 condyle passing first backward, then inward, forward, 
outward and so to backward again. 

The wrist joint gets its arterial supply from the anterior 
and posterior carpal arches of the radial and ulna. The inter- 
osseous 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. 



LIGAMENTS. 129 

Articulation of Carpus and Metacarpus. 

The bones of the carpus, which lie in the same row, are held 
tog-ether by ligfamentous fibres passing" across them in front 
and behind, palmar and dorsal ligaments, and by fibres which 
seize the adjoining- surface of opposing- bones, called interosse- 
ous ligaments. Between the trapezium and trapezoid there is 
no interosseous ligament. In the same manner the metacarpal 
bones of the four fing-ers are held tog-ether at their bases. The 
two rows of carpal bones are held tog-ether by lig-amentous 
fibres passing from one to the other in front and behind, pal- 
mar and dorsal lig-aments, and by two lateral lig-aments, the 
external passing- from the scaphoid to the trapezium, the inter- 
nal from the cuneiform to the unciform. 

The metacarpal bones of the four fing-ers are held to the 
second row of carpal bones by fibres in front and behind, pal- 
mar and dorsal lig-aments, and in one situation by interosseous 
fibres extending from the adjacent parts of the os mag-numand 
unciform to the bases of the third and fourth metacarpal bones. 

The synovial membrane between the first and second rows 
sends prolong-ations 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^ 
circumduction. 

The Metacarpo-Phalangeal Articulation. 

The knuckle joint, or metacarpo-phalang-eal, is of the mova- 
ble class and condyloid variety. The condyle is furnished by 
the head of the metacarpal bone and the receiving- cavity by 
the top of the corresponrling- phalanx, aided by a plate of carti- 
lag-e known as the anterior lig-ament of the joint. 

Des Anat— 9 



130 DESCRIPTIVE ANATONY. 

The lig-aments are tzvo latercil^ seizing- both bones on their 
lateral aspect just beyond the articular surface. The place of 
a posterior llg-ament is supplied by the extensor tendons of the 
finger. The anterior is not a lig-ament in the true sense of the 
word, being only amassof fibro-cartilaginous material attached 
to the front edg-e of the articulating- surface on the base of the 
phalanx, and increasing the receiving* cavity. 

To this lig-ament 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 hing-e variety, 
the trochlear surface being presented by the head of one pha- 
lanx and the receiving- surface bv the base of the other. 

The lig-aments, anterior and tvjo laterrl, are attached like 
those of the metacarpo-phalang-eal articulations, the extensor 
tendons here, also, taking- the place of posterior lig-aments. 

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 dig-ital branches both for nerves 
and arteries. The movements of the carpal joints are confined 
to a slig-ht gliding- of one bone on the other, — the same state- 
ment applying- to the carpo-metacarpal joint, except the thumb. 
Movement at the metacarpo-phalangeal joint consists of the 
four ang-ular movements and their combination, circumduction. 
Movement is freer at the index and little fing-ers than at the 
other two. Movement at the inter-phalangeal articulation is 
confined to flexion and extension. 

Temporo-Maxillary Articulation. 

This articulation is formed by the condyle of the lower jaw 
and the g-lenoid cavity of the temporal bone. 

This is a diarthrodial joint of the condyloid variety, and 
presents four lig-aments, viz : internal and external lateral, 
capsular and stylo-maxillary and an inter-articular fibro-car-^ 
tilage, which is sometimes perforated ; when this is the case, 



LIGAMENTS. 131 

there is but one synovial sac, otherwise there are two, one be- 
tween the cartilage and the condyle and the other between 
the cartilao^e and the g-lenoid cavity. 

The external lateral lig-ameut is attached to the zyg^oraa 
above, from its tubercle forward, and, passing- downward and 
backward, is attached, below, to the outer border of the neck 
of the condyle. 

The internal lateral liaament is a specialized piece of the 
deep cervical fascia, attached above to the spine of the sphe- 
noid and below to the shelf of bone forminor- the lower margin 
of the inferior dental foramen. 

The capsular ligament consists of fibres of varying thick- 
ness, attached above around the articular margin of the glen- 
oid cavity and below to the neck of the condyle 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 throughout its circum- 
ference to the edge of the interarticular cartilage. 

The intcr-ariicular fibro-cartilage 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-maxillary is, properly, not a ligament of this 
joint. It extends from the styloid process of the temporal 
bone to the angle and posterior border of the ramus of the 
lower jaw. 

The lower jaw receives its nervous supply from the auri- 
culo- temporal branch of the inferior maxillary. The arterial 
supply is from the temporal. 

The joint is strengthened on the outer side by the masseter, 
internally by the internal pterygoid and above by the tempo- 
ral. 

The movements are elevation and depression, lateral and 
forward 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 



132 DESCRIPTIVE ANATOMY. 

carried farther, both condyle and cartilag-e roll forward on 
the eminentia articularis, exag-g-erated 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 g-lenoid cavity on 
the side toward which motion is made. 

In forward movement the two condyles are drag-g-ed forward 
on the eminentia articularis, the lower jaw being protruded 
beyond the upper. 

Costo-Sternal Articulation. 

The ribs have attached to their anterior extremities the cos- 
tal cartilag-es, which prolong- the seven true ribs to the side of 
the sternum, where the cartilagfes are received into the pits 
found there and are held in place by lig-amentous fibres passing- 
from them to the sternum in front and behind. The cartilag-es 
of the second and third ribs have also each an inter-articular 

lig-ament. 

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 innominatum 
of each side and that between the two ossa innominata. 

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, ^vith the addition 
two ligaments on each side, the ilio-lumhar 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 lumbo- 
sacral passes from the transverse process of the fifth lumbar 
vertebra downward and outward to the wing- of the sacrum. 



LIGAMENTS. 133 

The Sar?'o- Coccygeal lig-aments are an intervertebral disk, 
small and insignificant, and an anterior, posterior and lateral 
lig-aments passing- directly from one bone to the other. 

The Sacro-Iliac articulation, symphysis or synchondrosis, 
is formed bv the auricular facets found on the sacrum and 
ilium, each of which is coated, in the recent state, by a thin 
plate of cartilaofe. The lig^aments of the joint are an anterior 
and a posterior and the two sacro-sciatic, g^reater 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 lig-ament is a dense and thick mass 
of fibres, both oblique and horizontal, passing- between the 
contig-uous surfaces of the two bones and filling* in the deep 
depression which exists between them. The fibres are 
attached to the roug-h surface on the ilium behind the auricu- 
lar 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 g-reater sacro-sciatic ligament is attached by its poste- 
rior extremity to the posterior inferior 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 isch- 
ium and is attached to the tuberosity of the ischium, its inner 
edg-e being- free and curved upward upon itself. 

The lesser sacro-sciatic ligament is blended with part of 
the g-reater at its posterior extremity, being- attached to the 
side of the sacrum and coccyx, slig-htly in front of the greater, 
and not extending- so hig-h 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 g-reater sacro-sciatic foramen; while that part of the 
g-reater sacro-sciatic which extends from the point where the 
two lig-aments 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 
between the two pubic bones, and is known as the symphysis 



134 DESCRIPTIVE ANATOMY. 

pubis. Kach bone presents an oval articular surface, whose 
long- diameter is downward and backward, coated by a thin 
plate of encrusting- cartilag-e. The two plates are in contact 
only at the back part, leaving-, in front, a wedg-e-shaped space 
filled by fibres passing- between the two plates. Besides this 
interarticular lig-ament, there are four others — superior, con- 
sisting- 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 consisting- of similar fibres behind. 

The articulations are supplied by branches from the lateral 
sacral, ilio-lumbar, middle sacral and internal pudic arteries. 

The nerves are received from the cords of the sacral plexus. 

The Hip Joint. 

The Hi j) Joint is one of the ball and socket articulations, of 
course, belong-ing- to the euarthrodial, or movable variety. 
The bones which ent^r-fdto 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 Pubes, which compose the os innoniinatum. This 
cavity is articular throug-hout its entire extent. There is a 
lower, inner portion, at the bottom of the cavit}^ a non-articu- 
lar roug-hened surface, which in the articulated skeleton serves 
partly to form the attachment of the lig-ament w^hich 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 lodg-es the blood vessels which supply the joint and 
prevents pressure upon these vessels. 

The Ligaments which hold the bones tog-ether are the 
Capsular lig-ament, which surrounds the joint; the Cotyloid, 
which surrotlnds the marg-in of the cavity, and serves to 
deepen it ; the Transverse, which crosses the cotyloid notch ; 
and in, the interior of the articulation, there is a round 
cord which is known as the Lig-amentum Teres. Some anato- 
mists add other ligaments, which are unimportant when con- 



LIGAMENTS. 135 

sidered as separate lio*aments, being- merely portions of t 
capsular lig-ament which are developed by the strain upon the 
joint. One of these, the Ilio femoral lig-ament, extends from 
just behind the anterior inferior spinous process of the ilium 
across to a point close to the Trochanter mijor of the femur, 
one of the points at which the strain is very great. Another, 
called the Ischio-femoral, extends from the tuberosity of the 
ischium ; while a third, somewhat less important than the 
others, extends from near the femoral line of the os pubes, and 
is known as the Pectineal, or Pubo-femoral lig-ament. These 
lig-aments are not deserving- of a separate name. The proper 
description is to say that the capsular lig-ament is streng-thened 
at the superior and inferior extremities of the joint by fibres 
which come respectivel}'^ from the spinous process of the ilium, 
from the ischium, and from the os pubes. 

The Capsular Lig-am2)it, thick and powerful, is attached 
above to the brim of the Acetabulum. As it passes around 
downward and backward, it will be noticed that the lig-ament 
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 lig-ament is found to occupy all the space above the g-roove 
on the ischium. On reaching- the upper, inner portion of the 
joint it expands considerably^ nearly to the ilio-pectineal line. 
As the li(jfa.ment passes downward it completely envelops the 
joint; and its attachment is ag-ain irreg-ular when the attach- 
ment to the femur is reached. Superiorly it extends to what 
is known as the superior cervical txibercle, which is found pro- 
jecting- from the upper front part of the neck at its junction with 
the trochanter major; superiorly to this, it extends behind a 
part of the Trochanter major; then follows the spiral line, 
and winds around until it passes just in front of the Tro- 
chanter minor; then extends until it passes upward and just 
misses the dig-ital pit, and reaches the starting--point. 

One of the most important of the lig-amentary bands com- 
posing- the Capsular lig-ament is the so-called ""T Lig-ament,''^ 
which may be seen better in the dry specimen than in the 
recent. The two branches rise by the "tail" or "stem" of 



136 DESCRIPTIVE ANATOMY. 

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 lig-ament are attached to the 
superior cervical tubercle: the inferior fibres are inserted into 
the spiral line just as they reach the inner aspect of the bone. 

The others are of comparatively little importance. 

The Ilio-^ectineal lig-ament is a long- slender baud of fibres, 
which starts nearly at the pectineal line of the pubes ; and 
passes down to reach the spine, a little lower. The band 
which comes from the tuberosity of the ischium arises just 
below the g-roove ; and then stretches across, to be inserted 
near the digital pit close to the Trochanter major. These 
ligamentous bands are of comparatively little importance. 

The Cotyloid cavity is deepened by a ring of fibro-cartilage, 
which is described as being nearly a complete circle, but fails 
to extend all the way around the joint ; that is, it is said to be 
horse-shoe shaped, the direction of the bend in the horse-shoe 
being downward and inward at the cotyloid notch. What is 
in reality a continuous ligament, extending all the way around 
the joint, anatomists have preferred to describe as two liga- 
ments, differentiating between the Cotyloid lig-amejit and the 
Transverse ligament^ which passes across the cotyloid notch, 
becoming continuous at its extremities with the cotyloid liga- 
ment, although the two have the same histiological structure. 
However, in accordance with general usage they are to be 
described as two separate ligaments. The Cotyloid lig-ame7it 
is described as being triangular upon cross section, although 
it is not quite so, the outer face being distinctly convex, the 
inner upon the cross section proving to be not a straight line, 
but a curved line, thus forming the concavity which is neces- 
sary to receive the convex head of the femur. The thin edge 
projects away from the bone ; the thick edge is attached to 
the margin of the cavity all the way around. 

As above described, the Cotyloid ligament upon reaching 



LIGAMENTS. 137 

the cotyloid notch, changes its name, and becomes the Trans- 
verse lig-ament, which is therefore merely a continuation of 
the Cotyloid. 

The Lig-amentiim Teres is a band of lig-ameutous fibres, 
holding- the bones which form the joint in position. It is at- 
tached to the margin of the depression 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 depres- 
sion on the head of the femur. 

In this, as in all other movable joints, there is a synovial 
membrane, w^hich here presents one peculiarity. Though the 
Ligamentum Teres has been spoken of as a ligament, it is not 
a liofament in the true sense of the word. As a rule the 
synovial membranes disappear as they approach the region of 
pressure in a bone ; but the Ligamentum Teres can be dis- 
tinctly demonstrated as a synovial membrane at the points of 
greatest pressure. The synovial membrane 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 Liga- 
mentum Teres. The Ligamentum Teres, therefore, does 
not enter into the joint 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. 

The Movements of which the hip joint is capable are, of 
course, all of the movements of the enarthroidal 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 
specimen flexion may be continued until there is almost a com- 



138 DESCRIPTIVE ANATOMY. 

plete revolution of the joint. The movement consists simply 
of spinning- the head in tHe cavity. There is no chang-e of 
position with reference to the ball in the socket, the ball simply 
turning- in the socket on an axis drawn through the Trochanter 
major from the centre of the head of the femur. 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 thig-h. 

Extension, the movement of the thig-h backward, is much 
less free than flexion. The movement is hindered by the 
Pectlno-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 
without rotation. In Abduction, which is a movement of the 
thig-h away from the mid-line of the body, as the limb is carried 
outward, the head of the femur passes downward to the bottom 
of the acetabular cavity, so that it can be felt throug-h the 
lig-amentous 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; if taken in a position of semi-flexion, adduction can 
never be equal to abduction, because it is checked by the pow- 
erful superior fibres of the capsular lig-ament. 

Circuinduction is a combination of all the preceeding- move- 
ments. In this movement the limb pisses from flexion to 
abduction, from abduction to extension, from extension to ad- 
duction, 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 line is more 
nearly through the centre of the lower extremity of the femur. 



LIGAMENTS. 139 

The muscles which strengfthen the joint are as follows: 

Above, the rectus and g-luteus minimus. In front, the psoas 
magnus and iliacus internus. Internally, the pectineus and 
obturator internus. Behind, the outward rotators of the thig-h, 
obturators, internus and externus, pyriformis, the g-emelli 
and the quadratus femoris. Or, beg-inning- at random and 
naming- them in the order in which they lie around the joint, 
we have, g-luteus minimus, rectus, iliacus internus, psoas 
mag-nus, pectineus, obturator externus, quaratus femoris, 
g-emellus inferior, obturator internus, g-emellus superior and 
pyriformis. 

The arteries supplying- the joint are derived from the obtu- 
rator, sciatic, internal circumflex and g-luteal. 

The nerve supply for the joint is draw^n from articular 
branches from the sacral plexus, g-reat sciatic, obturator, 
and a filament from the branch of anterior crural supplying- 
the rectus muscle. 

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 
weakest 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 extended to four, as some of the cartilages which enter 
into the formition of the joint are so arranged as to establish 
an articulation between themselves and the bones to which they 
are attached. The condyles and their receiving cavities per- 
mit all of the movements belonging to the usual condyloid 
articulations. The mistake of calling the knee a hinge joint 
arises from the fact that the classification of joints is based on 
the movements of which the joints are capible and not on the 
shape of the bones which enter into their formation. 

The Bones which compose the knee joint are the two condyles 
of the femur, the two glenoid cavities on the upper extremity 



140 DESCRIPTIVE ANATOMY. 

of the tibia, and the posterior surface of the patella. The 
lig-aments which bind the bones together are divided into two 
sets: the external, or exterior lig-aments, and the interior 
lig-aments. 

The Exterior Ligaments consist of an anterior, a posterior, 
an external lateral, and an internal lateral. 

The Anterior Lig-cunent, or Liganientam Patellar, the most 
powerful of all the bands of lig-amentous fibres attached to the 
joint, is nothing- more than the tendon of the E)xtensor triceps 
cruris. This muscle passes downward until it reaches the 
upper border of the patella. There the fibres become tendin- 
ous, and spread out to embrace the pitella, 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 anterior tubercle, where it is inserted, leaving- 
a little space between itself and the upper portion of the tibia, 

As the lig-amentum patellje descends towards its insertion, 
it does not diminish in size; but it g-ives off from its lateral 
aspect tendinous fibres, sometimes spoken of as the lateral 
patellar lig-aments, which pass around until they reach the 
joint; in other words, they form a complete capsule for the knee 
joint. This can be stated of every joint which carries a syno- 
vial membrane. 

The Posterior Lig-anie)it 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 attached above the condyles 
of the femur. Some are attached at those depressions where 
the Gastrocnemius and the Plantaris rise; and then extend 
across the upper marg-in of the condyloid notch. The 
central fibres extend further up on the shaft of the bone; but 
these instead of running- downward, run backward and out- 
ward. The central and enlarg-ed portion of the attachment of 
the Semi-menbranus muscle is inserted into the front of the 
femur, and spreads upward and backward, consequently 
forming- the middle portion of the posterior lig-ament of the 



LIGAMENTS. 141 

joint. Where the central fibres come in touch with the external 
head of the Gastrocnemius muscle, they blend with the fibres 
of that muscle. The lower fibres of the ligament are attached 
to the posterior surface of the tibia. 

The hiternal Lateral Lig-ament is attached above to the 
inner tuberosity of the femur; passes downward and is attached 
to the internal tuberosity of the tibia; but the fibres continue 
down to the internal face of the tibia. 

The External Lateral Ligament consists of two bundles of 
fibres; and is described by some as having- the same attachment 
below and a different attachment above. It is, properly speak- 
ing, all one ligament. Some anatomists assert that the muscle 
which passes over the joint constitutes the greater portion of 
the ligament, while others say that it does not enter into it at 
all. The origin of the Popliteus muscle and the origin of the 
long external lateral ligament of the knee joint are precisely 
the same thing. They are attached to the little groove on the 
outer surface of the outer tuberosity of the femur. From that 
point the external lateral ligament descends to become attached 
to the styloid process of the fibula. 

The remainder of it is nothing further than the tendon of 
origin of the Popliteus muscle. 

The interior of the Joint consists of a set of fibres, which 
are not ligaments, but are cartilages, without any function in 
binding the bones together. They serve mainly to deepen the 
cavit}', but are very peculiar in their arrangement, and have an 
entirely different function to perform. There is a synovial 
memVjrane between the cartilages and the tibia ; and it is 
between the semilunar cartilages and the upper extremity of 
the tibia that the fourth articulation, mentioned above as 
belonging to the knee joint, takes place. In the interior of the 
joint there are a pair of ligaments, or cartilages, the Semi-lu- 
nar cartilages; running across at the anterior aspect of the joint 
from one cartilage to the other is a small band forming a 
Tranverse ligament; binding these cartilages down to the 
bone are a set of very short fibres, known as the Coronary 
Ligarnenl ; then, in the interior of the joint, are seen two 



142 DESCRIPTIVE ANATOMY. 

strong- cords which cross each other somewhat in the form of 
the letter X, one called the Anterior, or External, Crucial 
Lig-avient, the other the Posterior, or Internal, Crncial Lig-a- 
ment. In addition we have the folds of synovial membrane, 
one called the Lig-amenticni Mucosum, and the other the Liga- 
ment a Alaria. 

The attachment of the Senii-hinar cartilages is one of the 
most important thing^s, both anatomically and surg-ically, in con- 
nection with the knee joint. ^]\q. Externarv$> nearly circular, 
being- but slig-htly oval in its outline; the Internal, on the con- 
trary, is distinctly oval, being" long-er from before backward than 
from side to side. The external is attached just in front of 
the spine of the tibia; and, in the prepared specimen, is attached 
just between the spine and the anterior crucial lig-ament, blend- 
ing- with the anterior crucial. Behind, it is attached between 
the crucial lig-ament and the internal cartilag-e, so that it blends 
at both extremities with the crucial ligaments. The internal 
semi-lunar cartilage, which is much long-er than the external, 
passes around so as to be attached in front of the anterior 
crucial lig-ament. It does not blend with that lig-ament at 
all ; and, behind, the internal cartilag-e is not attached to 
the crucial lig-ament. The cartilag-e can be raised up in any 
direction, but is attached to the bone by the fibres of the 
capsular lig-ament 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 lig-aments of this joint, 
with the exception of those composing- the Lig-amentum patellae, 
become attached to the edg-es of the semi-lunar cartilag-es; and 
from those edges they pass down as short fibres to seek their 
insertion in the tibia. They bind the cartilag-es in position, 
but leave them so as to be movable. 

The Anterior Crucial Ligament takes its orig-in from a 
point just in front of the spine of the tibia. Prom that orig-in 
it passes upward, 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; and is blended with the posterior extremity 



LIGAMENTS. 143 

of the external semi-lunar cartilag-e. From that orig"in the 
direction of its fibres is upward, forward and outward; and 
consequently the two crucial lig"araents cross each other in the 
joint. When they come in contact with each other, the poste- 
rior crucial ligfament g-ivesolf a slip of fibres which decussates 
with the anterior crucial lio-ament. The posterior lig-anient 
then passes on to its insertion in the external face of the internal 
cond^de of the femur. 

The folds of the Synovial Membrane are mixed with fat. 

The Ligamentum Mucosiun v^, io\xn6i attached to the front 
of the inter-condyloid notch; and passes from that point, lying- 
bet ween the patella and the inter-condyloid notch of the femur, 
down to become attached to the lower extremity of the patella. 

From the lateral edg-es of the ligamentum mucosum are 
sent off the fring-e-like folds with masses of fat, spoken of 
as the Lig-amenta Alaria. The synovial membrane is the 
largest in the body, and extends to surrounding struc- 
tures. The membrane passes down from the articular 
surface of the femur; and reaches the lig^amentum muco- 
sum, which has a few ligamentous fibres. It then ascends 
and reaches the patella on the posterior surface of the 
anterior lig-ament; but a lateral view of it would continue its 
course down until it reached the upper surface of the tibia. 
It is a continuous sack. The lateral subdivisions pass 
downward; and leaving- the femur, pass upward as far as the 
articular surface extends in the mid-line, including the crucial 
ligaments. Traced forward from the crucial ligaments, the folds 
pass over the upper surface of the tibia, run over and line the 
semi-lunar cartilages, and then pass between the cartilag-es 
and the tibia, so as to form a sack. As the fold passes down- 
ward, the crucial ligaments are left out of the joint, another 
proof that must at one time have been separate and distinct 
articulations. While the synovial membrane is all one continu- 
ous sack, there is a space above the articular surface of the 
femur, which covers the non-articular surface, extending* to the 
point where the attachment of the Gastrocnemius commences. 
The membrane surrounds and embraces the crucial lio-aments 



144 DESCRIPTIVE ANATOMY. 

and cuts them off from the joint; it extends down over the 
patella and the Ligfamentum patellae ; passes over the tibia, 
and in addition lies between the semi-lunar cartilag-es and the 
upper surface of the tibia, forming- a movable surface between 
the two. The membrane frequently communicates with little 
bursae which are found around this joint. 

The External Cartilage, just before it reaches its attach- 
ment, extends its transverse band across to become attached 
to the Internal Cartilage, thus forming- the Transverse lig-a- 
ment of the joint. 

Between the Li§ amentum patellcF and the upper surface 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 g-liding- 
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 burs^. Beneath the tendon on the inner 
side is found another ; and on the outer side, beneath the ten- 
don of the Popliteus, is found another. Any one of these may, 
and frequently do, communicate with the joint ; hence they 
are known as the Synovial Bursce. 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. 

Actions. 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 cartilag-es. Place the knee in a position of 
half-flexion, and the central portion of the cartilag-e then rests 
upon the central portion of the c'ondyle, the axis of rotation 
having- chang-ed so that the tibia has been carried forward 
about half an inch. Bring the leg" further forward, and the 
axis of rotation will have been brought further forward. 
When the joint is drawn into a position of extreme fl.exion, the 
toe is bent only slig-htly forward ; when we pass from extreme 
flexion to extreme extension there is an inward rotation, which 
bring-s the toe out until is nearly in a straig-ht line. That is, 
there is, in addition to the rotation of flexion, an axial rota- 



LIGAMENTS. 145 

tion, except for the fact that it takes place on two points 
instead of one. In addition to the movement between the 
femur and the tibia, there is, therefore, an actual rotation be- 
tween the semi-lunar cartilag-es and the tibia. Besides these, 
there is an incomplete rotation, a movement between the carti- 
lag-es and the femur ; and at the same place a constant move- 
ment of the patella on the femur. When the limb is in 
extreme flexion, only the lower portion of the patella is in 
contact with the femur ; when drawn up, the central or bulg-ed 
portion, is in contact with the femur ; and in extreme exten- 
sion, the upper 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 
compartments. 

The Muscles which strengthen the articulation are, prima- 
rily, the Triceps extensor cruris ; behind, the two heads of 
the Gastrocnemius 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 pow^erfully streng-thens the 
joint upon its outer side ; and it is a powerful streng-thening- 
agfent on its posterior aspect. 

The arterial supply of the joint is furnished 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 descending- branches 
from the external circumflex. 

The nerve supply is derived from the external and internal 
popliteal, the obdurator and from the anterior crural. 

The Tibio-Fibular Articulation. 

The upper and lower extremities of these bones are held 
tog-ether by lig-amentous 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 iva(S. posterior lig-a- 
mentous fibres, passing- directly between the contiguous sur- 

Des Anat— 10 



146 DESCRIPTIVE ANATOMY. 

faces of the two bones. They are united by a few scattered 
fibres to protect the synovial membrane, forming- an imperfect 
capsule. The synovial memhrane sometimes communicates 
with the knee joint. 

The inferior tibio-Jibular joint is an articulation of the 
amphiarthrodial class. A rough surface is presented by each 
of the bones for the reception of the powerful interosseous 
lig-ament which passes between them. There are also anterior 
and posterior fibres passing- from one bone to the other, form- 
ing 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 mem- 
brane communicates with the ankle joint. 

The interosseous vienibrane is composed of oblique fibres 
directed downward and outward and extending from just be- 
low 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 trans- 
mission of the anterior tibial vessels. At its lower portion the 
membrane is perforated for the passage of the anterior pero- 
neal 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 
twisting of the fibres of the interosseous ligament. 

The Ankle Joint. 

This/o/;?/ belongs to the movable class and hinge or, more 
correctly, the mortise and tenon variety. Its articular surfaces 
are contributed by the lower extremities of the tibia and 
fibula, above, and the upper surface of the astragalus below. 

The ligaments consist of anterior, posterior and two 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. 

Tho. 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. 



IvIGAMEXTS. 147 

The internal lateral or deltoid lig-ament, 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 
attached to the tuberosity of the scaphoid, to the inner face of 
the astrag-alus, below the articular facet, and to the os calcis, 
where it also serves to bind the astragalus and the os calcis to- 
gether. 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, the 
weakest, is attached above to the anterior border of the exter- 
nal malleolus and passing downward and forward reaches the 
upper, outer aspect of the astragalus. The middle, passes from 
the tip of the malleolus vertically downward to the tubercle on 
the outer face of the os calcis. The posterior 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. 

The joint is strengthened behind by the tendo Achilles, 
which takes the place of a posterior ligament. Antero-inter- 
nally is the tibialis anticus, postero-internally the tibialis pos- 
ticus while externally are the two peroneal tendons. The 
flexor and extensor tendons are too lax to add any strength to 
the joint. 

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 sur- 
face of the astragalus moving slightly backward in the receiv- 
ing 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 posi- 
tion a slight degree of lateral movement is permitted. 

The Articulations of the Tarsus. 

The articulations of the tarsus consist of the articulation 
between the bones of each row and the union of the two rows. 



148 DESCRIPTIVE ANATOMY. 

Calcaneo-Astragaloid Articulation. 

The two bones of the first row of the tarsus are held together 
by three ligaments, external, posterior and interosseous. 

The exierfial calcaneo-astrag-aloid ligament 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. 

The -posterior calcaneo-astragaloid passes from the posterior 
extremity of the astragalus to the contiguous upper aspect of 
the OS calcis and is but a continuation of the protecting fibres, 
called the posterior ligament of the ankle. 

The interosseous 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 be- 
tween 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 
passing 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'v^ 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. 



LIGAMENTS. 149 

The lo72§' inferior calcaneo-ciiboid ligament is attached be- 
hind 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 meta- 
tarsal bones of the second, third and fourth toes. It is much 
thicker and stronger, as well as longer, than the short inferior 
calcaneo-cuboid, which lies immediately above it. 

The short inferior calcaneo-ciiboid ligament 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, b}" 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 lig-ament, the other arm 
being furnished by the internal calcaneo-cuboid, passes for- 
ward and inward from the front upper part of the os calcis to 
the scaphoid. 

The inferior calcaneo 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 scap- 
hoid is the superior astrag-alo-scuphoid which is thin and weak 
and passes from the neck of the astragalus to the upper sur- 
face 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 wMth 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 metatarsus by dorsal "AXiA plantar 
lig-amentous fibres and by three interosseous lig-aments — one 



150 DESCRIPTIVE ANATOMY. 

from the internal cuneiform to the second metatarsal and one 
from the external cuneiform to the third metatarsal. 

The metatarso-phalangeal, the inter-phcdang-eal and the 
'' inter metatarsaV are exactly similar to those of the hand. 

Costo- Vertebral Articula,tion. 

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 interverte- 
bral disk. 

This articulation is of the diarthrodial class and the arth- 
rodial variety. The ligfaments which connect the head of the 
rib with the vertebral column are the anterior costo-vertebral, 
capsular and interarticular. 

The anterior costo-vertebral 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 interverte- 
bral 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 attached to only one vertebra, as the 
articular facet is furnished wholly by one vertebra. 

The capsular lig-ament consists of a few scattered fibres 
around the articulation. 

The interarticular lig-ament is attached to the ridge on the 
head of the riband to the intervertebral 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 interarticular ligament and but one synovial sac. 

The articulation between the ribs and the transverse pro- 
cesses, known as the costo-trans verse articulation, presents three 
ligaments — anterior, middle and posterior costo-transverse. 

The anterior costo-transverse extends from the neck of the 
rib to the transverse process above; the jfiiddle, or interosseous, 
extends from the posterior surface of the neck of the rib di- 
rectly backward to the transverse process; t\iQ. posterior extends 
from the tubercle of the rib to the apex of the transverse 
process. 



THE VISCERA. 151 

THE VISCERA. 

The Alimentary Canal and Appendages. 

. The alimentary canal beg-ins at the mouth and ends at the 
anus, the intermediate portions being- found in the neck, thorax 
and abdomen. In the neck are \h.<$. fauces , pharynx and part 
of the aesophag-ns; 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 beg-ins 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 tong-ue and on each 
side by the cheeks. 

The lips are two, upper and lower, separated by the trans- 
verse labial fissure. Each is formed chiefly by itsseg-ment of 
the orbicularis oris muscle, covered externally by skin and 
internally by mucous membrane, a concentric fold of which, 
called frcjenum labii, extending- in the middle line from each lip 
to the g-um behind. The cheek consists chiefly of the buccin- 
ator muscle, covered externally by skin and internally by mu- 
cous membrane, which is reflected from it to the g-um and 
presents, opposite to the second molar tooth of the upper jaw, 
the opening-, on a papilla, of Stenson's duct from the parotid 
g-land. 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 boundfed'"in front and at either side by the 
aveolar processes 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 fossa} 
above and the roof of the mouth, below ; on the latter aspect 
the mucous membrane is roug-hened by g-lands, called palatal, 
and is continued on to the g-ums. 



152 DESCRIPTIVE ANATOMY. 

The floor of the mouth is formed by the anterior two-thirds 
of the tong-ue, the posterior third the tong-ue forming- the 
floor of the fauces, and, below that, entering" into the forma- 
tion of the anterior wall of the pharynx. 

The tongue is flattened from above downward, is conical 
in shape and curved in direction, being- convex above antero- 
posteriorly, 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 tong-ue 
passes around the sides and tip, thus enveloping- most of the 
org-an, and leaves the lower surface to become continous with 
that lining- the g-um of the lower jaw. In contact with the 
posterior part of the dorsum is the front of the epig-lottis, 
which is held to it by three folds of mucous membrane, the 
g-losso-epig-lottic lig-aments, middle and two lateral. 

The mucous membrane covering- the tong-ue and mouth is 
continued back throug-h the fauces to blend with that which 
lines the g-uUet. 

The Fauces. 

'\^\\Q. 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- g-reatly, 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 tong-ue; the sides are formed by two 
arching- muscles, and, between them, the tonsil g-lands. The 
muscle in front is the palato-g-lossus, forming- the anterior 
pillar of the fauces; that behind is the palato-pharyng-eus, 
forming- the posterior pillar of the fauces. The wall, in every 
aspect, is covered by mucous membrane. 

Soft Palate. 

The soft palate, or velum penduluni palati, is thin and 
flattened from above downward and forward. It is attached 



THE VISCERA. 153 

above to the posterior border of the hard palate aad hangs 
downward and backward, separating- the fauces from the 
upper part of the pharynx. It is prolong-ed, 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, vix : the mouth and fauces. Leav- 
ing the latter, food enters the pharynx, whence it passes to 
the (esophagus, 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 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 Eusta- 
schian tube ; and a lower portion receiving the opening of the 
fauces above and opening into the oesophagus below. By its 
musculo-aponeurotic fibres is attached to all of the surround- 
ing firm structures, base of the occipital bone, pterygoid pro- 
cesses of the sphenoid, base of the tongue, hyoid bone, infe- 
rior maxillary 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 sur- 
rounding 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 where the 
pharyngeal aponeurosis is thicker than elsewhere. In the 
anterior wall, above the soft palate, the openings of the poste- 
rior nares are seen on either side ; while further out and oppo- 
site the posterior extremity of the inferior turbinated bones, 
may be seen the openings of the Kutaschian tubes. 



154 DESCRIPTIVE ANATOMY. 

Below the soft palate the opening- for the fauces ocupies the 
whole of the anterior wall, while below this is the antero-pos- 
terior opening- of the larynx, behind which is the transverse, 
slit like opening into the oesophag-us. The pharynx is sepa- 
rated from the front of the bodies of the upper five cervical 
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 is throughout made up of an inter- 
nal 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. 

The Tong-iie 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 following : 

Extrinsic 
Stylo-Glossus Hyo-Glossus 

Palato-Glossus Genio-Hyo-Glossus 

Intrinsic 
Superior Lingualis Inferior Lingualis 

Vertical Lingualis Transverse Lingualis 

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, 
forward 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 mus- 
cle blend with those of the superior and inferior lingualis. 

The Hyo-Glossiis is a flat quadrilateral muscle which arises 
from the side of the body and both cornua of the hyoid boue. 



THE VISCERA. 155 

passes directly upward and is inserted into the whole length 
of the tong-ue, to the inner side of the Stylo-Glossus, its fibres 
blending^ with the vertical ling-ualis. 

The Palato-Glossus is a small muscle found occupying the 
anterior fold of the fauces. Arising- in the soft palate it pas- 
ses downward and inward and is inserted into the side of the 
tongue, its fibres blending with the transverse lingualis. 

The Goiio-Hyo-Glossus is a thin, radiated, fan shaped mus- 
cle found lying close beside its fellow near the mid line and 
extending 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 are all, except the Palato-Glossus, supplied 
by the hypoglossal nerve. The Palato-Glossus is supplied by 
branches from the pharyngeal plexus. The lingual artery is 
the source of the blood. 

The Tongue I?, divided by a vertical fibrous septum which 
occupies the middle line and receives the insertion of the 
transverse lingualis muscle. The intrinsic fibres, largely de- 
rived 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 tong-ue. 

Aclion. 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- Glossiis can 
draw the tongue upward and backward, or, if one muscle alone 
acts, upward, backward and toward the side of the muscle 
acting. The Ifyo-Glossiis draws the tongue downward and 
backward, increasing the si/.e of the fauces and aiding the 
intrinsic fibres in shortening the organ. The Pa/a/o-Glossiis 
widens the tongue and elevates its base, depresses the soft 



156 DESCRIPTIVE ANATOMY. 

palate and constricts the fauces while the Genio-Hyo- Gloss us 
draws the tong-ue forward by its posterior fibres, shortens it 
by the approximation of posterior and anterior, while the central 
fibres depress the org-an and make the dorsal face concave. 
The lower fibres can draw upward and forward the hyoid bone. 

Muscles of the Soft Palate. 

L/evator Palati Tensor Palati 

Azyg-os Uvulse Palato Glossus 

Palato-Pharyng-eus 

The Palato-Glossus was described with the muscles of the 
tongue. 

Levator Palati, 

The levator palati arises from the roug-h surface on the 
basilar face of the petrous bone, near its apex, and from the 
cartilag-inous portion of the E^ustachian 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 rig-ht 
ang-le on itself, hence its synonym of circumflexus. It arises 
from the scaphoid fossa of the pteryg"oid process, from the 
spinous process of the sphenoid bone and from the cartilag-i- 
nous portion of the E)ustachian tube, and, first descending- 
vertically, then turning" transversely inward around the 
hamular process, it spreads out into a broad aponeurosis in 
the soft palate. Its action is indicated by its name. 

Azygos Uvulse. 

From the posterior termination of the soft palate there hang's 
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 palate 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. 



THE VISCERA. 157 

Palato-Pharyngeus. 

The Palato-Pharyug-eiis 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 thethj^roid cartilag-e. Its action is the 
same as the preceding- muscle and its synonym is constrictor 
isthmii faucium posterior. 

The Muscles of the Pharynx. 

The Pharynx is lined by raucous 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 lon- 
gitudinal fibres, but differing in that the muscular fibres are 
here red and not pale, and are gathered into bundles which 
are described as separate muscles. The circular fibres are 
arranged in flattened bundles on each side, each bundle inter- 
secting its fellow of the opposite side on the middle of the 
back of the pharynx where they form a raphe. Each pair of 
bundles overlaps 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 mus- 
cular 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 em- 
braced 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 supe- 
rior, middle and inferior constrictors. The direction of their 
fibres is not horizontally backward but backward 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 two upper rings of 
the trachea. It runs backward and upward, its upper fibres 



158 DESCRIPTIVE ANATOMY. 

passing* obliquely upward, overlapping- the middle constrictor 
and is inserted into the raphe of the pharynx. 

Middle Constrictor. 

The middle constrictor 2lx\'s>q.^ from bothcornua of the hyoid 
bone, and from the stylo-hyoid lig"ament, a fibrous cord extend- 
ing- from the hyoid bone to the styloid process. The fibres 
radiate somewhat, spreading- out on the side of the pharynx, 
and are inserted into the raphe. The inferior fibres are over- 
lapped by the inferior constrictor, and the superior fibres 
overlap the superior constrictor. So g-reat is this overlapping- 
that when viewed from behind but little of the superior con- 
strictor can be seen, the raphe of the middle constrictor ex- 
tending- 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 one-third 
of the internal pteryg-oid plate, from its hamuiar process, from 
the pteryg-o-maxillary lig-ament, from the extremity of the 
molar ridg-e of the lower jaw, and by a few fibres from the 
side of the tong-ue. It passes backward and is inserted into the 
raphe, which is attached to the basilar process. The upper 
edg-e 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 ^f the phar- 
ynx extends and is here so much thickened as to form a strong- 
fibrous membrane. 

The long-itudinal fibres of the pharynx are, like the circu- 
lar, g-athered 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-pharyng-eus, has been described as a part of the soft- 
palate ; the other is known as the stylo-pharyng-eus. 

Stylo-Pharyngeus. 

The stylo-pharyng'eus arises from the inner side of the base 
of the styloid process and descends to the side of the pharynx, 



THE VISCERA. 159 

enteriiig- its wall between the superior and middle constrictors. 
Some of the fibres are lost in the pharynx, while some are 
continued to the posterior border of the thyroid cartilag-e. 
Action — it elevates and widens the pharynx. 

(Esophagus. 

The CEsophagus continues the course of the alimentary 
canal from the termination of the pharynx, at the commence- 
ment of the trachea on the front of the body of the fifth cervi- 
cal vertebra, down the front of the vertebral column, throu^-h 
the neck and thorax, to pierce the diaphrag-m at the (esopha- 
geal opening-, opposite the tenth dorsal vertebra, and terminate 
at the cardiac orifice of the stomach. It is about nine inches 
long-. 

In structure the oesophag-us resembles the pharynx, but its 
muscular coat is not arrang-ed in distinct bundles. It is the 
narrowest part of the alimentary^ canal, but the most muscular. 

Relations of Pharynx and (Esophagus. 

In addition 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 jug-ular 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 ling-ual lies on the middle constrictor. 
Below the upper border of the thyroid cartilag-e the common 
carotid becomes the external relation. 

Relations of the (Esophagus. 

The relations of VtiQ CEsophagus must be studied in the neck 
and in the thorax. The g-uUet is about nine or ten inches in 
leng-th, 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 straig-ht tube but presents antero-posterior curves, 
corresponding- to the curvatures of the spinal column. There 



160 DESCRIPTIVE ANATOMY. 

are also three lateral curvatures — two to the left and one to the 
risfht. At its commencement it lies on the middle line of the 
body but curves to the left until it reaches the root of the neck. 
From this point it curves to the rig^ht until it ag-ain reaches 
the middle line, opposite the fifth dorsal vertebra, and from 
there passes steadily to the left ag-ain until it terminates oppo- 
site the body of the tenth dorsal vertebra. 

In the cervical, and upper part of the thoracic portions, the 
oesophag-us is separated from the front of the vertebral column 
by a layer of fascia and by the long-us colli muscles, particu- 
larly 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 gfland, except that the left 
lobe of the latter touches the oesophag-us 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 g-roove between 
the trachea and oesophag-us. 

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 oesophag-us to its termination. Laterally the g-ullet is 
in contact with the two pleurae, although the left is a relation 
for a g-reater distance than the right. To the rig-ht above, 
and separated from it by the trachea, is the innominate artery, 
and below this, the vena azyg-os major is for a moment to the 
right side. On the left is the left common carotid artery, 
while the left subclavian is a more distant relation. 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 
are the longus colli muscle above, and the recurrent laryngeal 
nerve of the left side from the transverse aorta upward. The 
thoracic duct is a posterior relation throughout the thoracic 



THE VISCERA. 161 

portion, but, below the transverse aorta, lies in the interval 
between the aorta and the oesophag-us. The vena azygos major 
is a posterior relation, while the azyg-os minor crosses behind, 
opposite the sixth dorsal vertebra. The right pneumog*astric 
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 oesophao-us first has the transverse aorta in front, then 
the descendinor aorta first to its left side, then behind and, at 
the termination of the oesophao-us, the aorta is to the right 
and behind. 

The Abdominal Viscera. 

The cavity of the abdomen is bounded above by the diaphragm, 
which is a thin arched muscle with its cavity downwards, form- 
ing the floor of the chest and the roof of the abdomen. 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 fossas, 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, &c. , 
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 w^all 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 description 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 processes 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 IIypocho}idriuc, right and left ; the central region in the 
middle zone Is the Umbilical, the one on either side Lumbar y 

Des Anat — 11 



162 DESCRIPTIVE ANATOMY. 

rig-ht and left ; the central region in the lower zone is the 
Hypogastric, the one on either side, iliac, rig-ht and left. 

The contents, of the abdomen are the greater part of the 
alimentary canal, the accessory org-ans of dig^estion — liver, 
spleen and pancreas — and the g^enito-urinary org-ans — kidneys 
and supra-renal capsules, the bladder and its appendag-es, 
prostate gland, seminal vesicles and vas deferens. The 
testicles are considered vv^ith the abdominal viscera, althoug-h, 
in the '^Udult, lying in the scrotum, outside the abdominal 
cavity. In the female there are the uterus and its appendages 
and the vagina. E^nveloping 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: 1st, iho. ^stomach; 2d, small 
intestine ; 3d, 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 epi- 
gastric from the right liypochandriac reg-ion in the small 
intestine. The small intestine is divided into three parts, 
diiodemun, jejiiniun and ileum. The diiodemim 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 subdi- 
vided into three portions, viz : first portion, ascending, or 
oblique duodenum, is about two inches long and terminates at 
the neck of the gall bladder, on the lower surf ace 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 por- 
tion 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 
caecum, colon and rectum. The caecum is the commencing 



THE VISCERA. 163 

two and one-half inches, lies in the rig-ht iliac fossa and termi- 
nates 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 passes upward 
throug-h the rig-ht lumbar reg-ion into the rig-ht hypochondriac. 
At the under surface of the liver it curves sharply to the left, 
forming- the hepatic flexure of the colon, and becomes the 
transverse colon. The transverse Q,<d\ovi passes downward and 
to the left, crosses the abdomen between the epig-astric and 
umbilical reg-ions and rising" into the left hypochondriac reg"ion 
forms another abrupt curve at the lower end of the spleen, 
called the splenic flexure of the colon, and becomes the descend- 
ing colon. The descending colon passes downward througfh 
the left lumbar reg^ion into the left iliac where it becomes the 
sig^moid flexure. 

The sigmoid flexure is that portion of the g-ut 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 larg-e intestine and terminates the ali- 
mentary 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 duodenum, crossing- the front of the body of the 
first lumbar vertebra. Each of the two kidneys is beside the 
lumbar portion of the spinal column, on the front of the pos- 
terior aVjdominal wall. The uriiiary bladder "A-w^ its append- 
ag-es are found in the pelvis just behind the os pubis. The 
iderus and vagina in the female, are interposed between the 
rectum and bladder. 

Reflections of the Peritoneum. 

The periloneiun, 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. 



164 DESCRIPTIVE ANATOMY. 

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 
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 la^-ers, 
which pass to the upper and lower edg-e 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 cov- 
ered 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 down- 
ward to the stomach, forming- between these two organs the 
gastro-hepatic or the lesser omentum. They reach the 
stomach at its upper border and divide, one passing- over 
the front and one over the back, and meet ag-ain at the lower 
border after furnishing a coat to the stomach. The two layers 
leave the stomach at its lower border and pass downward to 
to the transverse colon, pass over it without touching and 
descend almost to the brim of the pelvis, just behind the ante- 
rior abdominal wall ; they then reverse their course, run 
upward, just posterior to their descending course, reach the 
transverse colon, and, separating, 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 posterior abdominal wall. 
The two layers now finally separate; one goes up the posterior 
abdominal wall to the lower surface of the diaphragm, ^vhere 
its course was first taken up, thus partially enclosing a space 
behind the stomach called the lesser cavity of the peritoneum, 



THE VISCERA. 165 

which communicates with the g^eneral 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, holding- the intestine to 
the abdominal wall, called the mesentery. The attachment of 
the mesentery is thus stated : from the left side of the body of the 
second lumbar vertebra downward and to the right to the rig-ht 
sacro-iliac synchondrosis. After forming" the mesentery the 
peritoneum descends the posterior abdominal wall to the brim 
of the pelvis passes down its posterior wall, covering the upper 
half of the rectum completely, leaves the front of the rectum 
an inch below its middle, 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 
up it and 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, cover- 
ing its upper inch, then strikes the uterus passing up -its 
back and turning down its front whence it passes to the blad- 
der. 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 w^alls of the pelvis called the broad 
ligament of the uterus. Between these two layers are the 
ovary and its ligament, the round ligament of the uterus and 
the fallopian tubes. 

Followed transversely around the abdomen, about its 
middle, the peritoneum presents the following folds : com- 
mencing on the anterior abdominal wall it can be followed to 
the posterior abdominal wall, where it reaches the descend- 
ing colon and passes 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 nies- 



166 DESCRIPTIVE ANATOMY. 

entery; 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, reaches 
the abdominal wall ag-ain along- which it runs to the place of 
departure. 

Relations of the Abdominal Viscera — Stomach. 

The sto7nach lies in the upper zone, in the left hypochondriac 
and epigastric reg-ions, g-enerally terminating- in the duodenum 
on the line which separates the epigastric from the right 
hypochondriac reg-ion, but occasionally passing- more or less 
into the latter. Its long- axis is directed from above down- 
ward, from left to rig-ht and from behind forward; one surface 
looks forward, the other backward; one border, the shorter, 
or lesser curvature, upward, the other, the long-, or greater 
curvature, downward; the larg-e end is to the left, the small, 
to the rig-ht. It is continuous with the duodenum at the rig-ht 
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 g-reater omentum; its left end is 
connected with the spleen by the g-astro-splenic omentum. 
Above it are the diaphrag-m and the left lobe of the liver; be- 
low is the transverse colon, indirectly held to it by the g-reat 
omentum; to the rig-ht is the duodenum; to the left is the 
spleen, whose concave inner surface is in contact with the con- 
vex left extremity of the stomach; behind is the pancreas, 
immediately above which is the coeliac axis with its branches 
and the semi-lunar g-ang-lia, 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 com- 
plete peritoneal coat which forms for it three lig-aments, the 
lesser omentum holding- it to the liver, the great omentum sus- 
pending the transverse colon and the gastro-splenic omentum 
binding together the spleen and the stomach. 

The Oblique Duodenum. 

The oblique, or ascending- duodenum, commences at the 
right extremity of the stomach, usually on the line which sepa- 



THE VISCERA. 167 

rates the epio-astrlc from the rig-ht hypochondriac region, and 
passes upward and to the right, in the latter region, to termin- 
ate in the descending duodenum at the neck of the gall bladder 
on the lower surface of the liver. 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 -pej-pendicular, or descejiding duodenum, commences at 
the termination of the oblique duodenum, at the lower surface 
of the liver, at the end of the gall bladder in the right hypo- 
chondriac region, and descends vertically into the lumbar re- 
gion to terminate in the transverse duodenum, about on a level 
with the upper border 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 transverse diiodouun commences where the oblique 
terminates, in the right lumbar region, on a level with the 
upper border of the body of the fourth lumbar vertebra, 
and passing upward and to the left, across the body or 
the third lumbar vertebra, terminates in the jejunum at 
the left side of the body of the second lumbar vertebra. 
It lies behind the peritoneum, between the diverging layers 
of the transverse meso-colon, so that it is covered by perito- 
neum only in front. Above it is the lower border of the 
pancreas, from which it is separated by the superior mesen- 
teric artery and vein; in front is the transverse colon. 

The Jejunum and Ileum. 

The remaining twenty feet of the small intestine, follow- 
ing' the duodenum , are thrown into coils called the convolu- 
tirms of the small intestine, and are found chiefly in the 
umbilical and hypog-astric regions, falling off, however, into 



168 DESCRIPTIVE ANATOMY. 

surroundiug- regions, some being always found in the pelvis 
between the rectum and bladder in the male and the rec- 
tnni and uterus in the female. The jejunum comprises the 
upper two-fifths of the intestine and begins where the duode- 
num terminates, 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 perito- 
neum, which holds them by a double-layered fold to the pos- 
terior 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. 

The Ccecum. 

The caecum 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 peri- 
toneum. 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 opening of the ileum, and not into the bottom. 
The appendix has a complete peritoneal coat and lies slightly 
coiled on the inner side of the coecum and just below the ileum. 

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 termi- 
nates, 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 



THE VISCERA. 169 

it is held by a fold of the peritoneum, beings covered by it in 
front from half to three-fourths around. In front and to the 
outer side is the abdominal wall ; to the inner side, the convo- 
lutions of the small intestine, and the inferior vena cava ; 
behind, the perpendicular duodenum and rig-ht kidney, the 
duodenum being- to the inner and posterior aspect. 

The Transverse Colon. 

The transverse coloi commences at the termination of the 
ascending- colon, at the lower surface of the liver, in the hepa- 
tic 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 reg"ion, termi- 
nates 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 poste- 
rior abdominal wall and by a small band to the lower end of 
the spleen. It is indirectly held to the g-reater curvature of 
the stomach by the g-reat omentum. In front it is separated 
from the anterior abdominal wall by the g-reat omentum ; 
behind is the transverse duodenum ; above are the liver, stom- 
ach and spleen ; below, the convolutions of the small intestine. 

The Descending Colon. 

The descendiiii*' colon begins where the transverse colon 
ceases, in the left hypochondriac reg-ion at the lower end of 
the spleen, and passing- downward throug-h the left lumbar 
reg-ion terminates in the left iliac region by becoming- the sig- 
moid flexure of the colon. It lies behind the peritoneum, cov- 
ered bv it in front from 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 sig-moid Jlcxurc of the colon begins by being the con- 
tinuation of the descending colon in the left iliac region and. 



170 DBSCRIPTIVE ANATOMY. 

passing- down into the pelvic region terminates on the middle of 
the third piece of the sacrum by becoming- the rectum. The g"ut 
presents many differences in position, but, when empty, is 
usually found passing- downward and to the rig-ht, then falling 
over the brim of the pelvis and resting against its own lower 
portion and the beg-inning of the rectum. It is completely in- 
vested by peritoneum, which holds it by a fold of variable 
length to the abdominal w^all. It crosses the pelvic brim in 
front of the ureter, from which, as well as from the iliac ves- 
sels, it is separated by peritoneum. In the pelvis it lies in 
front of the internal iliac vessels and sacral plexus of nerves 
and comes in contact, on its inner side, with convolutions of 
the small intestines, 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 female, and bladder in the male, are interposed 
some convolutions of the small intestines. 

The Rectum. 

The rectum begins by being the continuation of the sigmoid 
fixture at the middle of the third piece of sacrum and termi- 
nates at the anus. It passes straight down the middle line, 
conforming to the curve of the sacrum and coccyx, until it 
reaches the tip of the latter bone when it turns backward, run- 
ning in this direction downward and backward for about an 
inch and a quarter when it terminates at the anus. At its 
commencement the rectum is covered by peritoneum about 
halfway 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 bladder in the 
male, or the back of the vagina, in the female. That portion 
of the rectum which is covered by peritoneum has upon its 
front convolutions of the small intestines 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 sacrel nerves, In front, below the peritoneum, it has 
the base of the bladder, prostate gland, seminal vesicals and 



THE VISCERA. 171 

vas deferens and is crossed on its side by the ureters. In the 
female the vag-ina rests upon the front of the g-ut, at first 
firmly attached to it but separated from it below by a widen- 
ing- 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 properlj^ an abdominal viscus, lying" in 
the ischio-rectal fossa. 

The Liver. 

The liver is found in the upper zone of the abdomen, the 
greater part being" in the rigfht hypochondriac and epigastric 
reg-ions, but projecting-, to a g-reater 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 lower margin of the ribs on the right ; its thick border is 
backwards, resting against the diaphragm and grooved 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 um- 
bilical 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 pos- 
terior 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 liga- 
ments 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 ligament, or the 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 longi- 



172 DESCRIPTIVE ANATOMY. 

tudinal lig-ament. The peritoneum reaching- the liver in the 
manner described, passes over it, one layer over the upper sur- 
face, 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 diaphrag-m, which separates it from 
the thorax, containing* the heart and lung's ; 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 blad- 
der, the oblique duodenum ; to the left of this the upper bor- 
der of the stomach, held to the liver by the lesser omentum, 
and, to the left of this, the spleen, suspended from the under 
surface of the diaphragm by the suspensoTy 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. 

T\iQsf)leen 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 peri- 
toneum, onefold, called the suspensor}^ 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 separated 
by the liver; below is the splenic flexure of the colon; behind 
the lower end is the left kidney and its 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 



THE VISCERA. 173 

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 f)ancreas 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 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 
w^hich it is separated by the superior mesenteric vessels. Its 
relation to blood vessels are very complex, and may be given 
as follows: it is separated from the vertebral column by the 
abdominal aorta, w^hich produces thecoeliac 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 cfjeliac 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, 



174 DESCRIPTIVE ANATOMY. 

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 slig-htly 
outward to about the crest of the ilium. Therig-htis 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 front of the organ by this tissue and can easily be stripped 
off. The long- diameter of the kidney is from above downward 
and slig-htly outward; one face looks forward and slig-htly out- 
ward, the other backward and slig-htly inward ; the upper end 
is, perhaps, the larg-er ; the outer border is convex, the inner 
concave. Throug-h most of its extent the kidney rests on the 
quadratus lumborum muscle, separated from it by the ante- 
rior lamella of the posterior aponeurosis, of the transversalis 
muscle. Along- its inner edg-e it lies on the psoas mag-nus 
muscle, and behind its upper part is the diaphrag-m, w^hich 
separates it from the pleura. The diaphrag-m here fre- 
quently presents a fissure of considerable size, where the mus- 
cular tissue is wanting-, so that, in this event, all that separates 
the kidnev from the pleura is a little loose connective tissue, 
li^ach kidney has upon its upper, inner, front part the supra- 
renal capsule. The outer border is nearly opposite the outer 
border of the erect or spin« muscle, and about corresponds to 
the junction of the posterior third with the anterior two-thirds 
of the crest of the ilium. 

The rig-Jit kidney has in front the descending- duodenum 
and in front of that the ascending- colon ; along- its inner bor- 
der 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 g-reat end of the stomach. 



THE VISCERA. 175 

The Bladder, in the Male. 

The 2(ri)iary bladder occupies the front portion of the pelvic 
cavity, being- confined to it when empty or nearly so, but ris- 
ing out of it according- to its state of distension, occasionally 
reaching- the level of the umbilicus. It lies just behind the 
S3'mph3^sis pubis with its long- diameter from above downward 
and backward, extending- from the upper border of the sym- 
physis pubis, or a point in the linea alba between it and the 
umbilicus, varying with distension, so that, if prolonged, it 
would strike the lower part of the front of the sacrum. 

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 
remains 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 lig-aments. 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 hypograstic 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. 

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 



176 DESCRIPTIVE ANATONY. 

lig-ament; and that part on each side, extending" from the side 
of the bladder to the lateral wall of the pelvis, forms the lat- 
eral false li^q-ament. 

The four remaining* true lig-aments are formed by the pelvic 
fascia, which lines the pelvic cavity just beneath the perito- 
neum. 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, the two being known as the two lateral 
trite lig'aments 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 pro- 
state g-land 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 rec- 
tum usually by some convolutions of the small intestine. The 
base of the bladder rests on the front of that part of the rec- 
tum 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 each having- just internal to it the vas deferens, 
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 seininal 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 g-land. 

In the female the bladder, in general terms, occupies the 
same position as in the male. There are no prostate glands, 
no vas deferens, or seminal vesicles. The base of the female 
bladder rests on the upper wall of the vagina and on the lower 



THE VISCERA. 177 

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 
posterior faces, somewhat flattened. The short border is 
known as the lesser curvature, the long- as the g-reater curva- 
ture. The larg-e end of the 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 car- 
diac orifice. The splenic end of the stomach is the dilated cul 
de sac bulging beyond this. 

The rig-Jit 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 dozunzuard, forzuard, and 
to the rig'ht the cardiac orifice being on a higher level and far- 
ther back than the pyloric. When empty, the anterior and 
posterior faces look almost directly forward and backward re- 
spectivel}'. 

The longest diameter of the stomach is about twelve inches, 
and it can receive from one to two quarts at a time. 

The Duodenum. 

The duodenum succeeds the stomach. It is about nine inches 
in length and forms a horseshoe-shaped curve whose convex- 
ity 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 o/jlignc portion. It passes upward, 
backward and to the right. The second portion, called the 
descending" or perpendicular duodenum, is about three inches 
Des Anat— 12 



178 DESCRIPTIVE ANATOMY. 

long' and passes downward. The third portion, called the 
transverse duodenum, begins where the descending- terminates 
and passing- across the vertebral column, terminates in the jeju- 
num, or second portion of the small intestine. The duodenum 
terminates at the left side of the second lumbar vertebra ; but 
the point where the jejunum becomes the ileum is arbitrary 
and ill defined. The jejunum begins where the duodenum 
terminates and comprises the upper two-fifths of the remain- 
der 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 hypogastric 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 begins by a sudden dilation 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 sinu- 
ous in its course and is divided into three portions, coecum, 
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 wdth 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 
commences at the entrance of the ileum, which is the mark of 
division between it and the coecum, in the right iliac region, 
and passes upward through the right lumbar region to the 



THE VISCERA. • 179 

lower surface of the liver, in the rig-ht hypochondriac region. 
This portion of the gut is called the asce)idi)i§ 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 
cavit}^ This portion is called the transverse colon and its 
course corresponds to the superior horizontal line of the abdo- 
men. At the lower end of the spleen, in the left hypochon- 
driac reg-ion, the colon makes another bend, called the splenic 
flexure, and turns downward to pass throug-h 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 sig-moid 
dexiire, which terminates at the brim of the pelvis, opposite 
to the left sacro-iliac s^^mphysis, in the rectum. The rectum 
begins where the sig-moid flexure terminates and passes down- 
ward on the front of the sacrum, to terminate at the anus, 
being- approximately straig-ht 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, 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 in- 
vesting- it, passes ofT to adjoining- parts forming- the omenta of 
the stomach which seem to retain it in its position. It is held 
to the liver by the g-astro- hepatic, or lesser omentum, to the 
spleen by the gastro-splenic omentum and to the transverse 
colon by the g-astro-colic, or g-reater omentum. 

2d Just beneath the serous coat is the long-itudinal muscular 
coat. 



180 DESCRIPTIVE ANATOMY. 

3d. Just beneath this is the circular muscular coat, which is 
thickest toward the pyloric extremity, w^hile the longitudinal is 
thickest at the lesser curvature. The fourth coat is a partial 
one, of oblique muscular fibres which diverg-e from the cardiac 
end of the stomach beneath the circular fibres and terminate 
before reaching- the pyloric orifice. The fifth coat is the inter- 
nal mucous coat, which, when the stomach is empty, is thrown 
into long-itudinal ridg-es, called rug-ae, which disappear when 
the stomach is distended. At the pylorus the mucous coat is 
thickened, and beneath this thickening- is an ag-g-regation of 
the circular fibres so as to produce a sudden contraction of the 
tube. This appearance is known as the pyloric valve. 

The duodemtm has four coats: 1st, serous; 2d, long-itudinal 
muscular; 3d, circular muscular; 4th, mucous membrane. In 
the commencement of theg^ut the mucous membrane is smooth, 
but it is soon thrown into folds, which pass around the g^ut 
from three-fourths to five-sixths of its circumference; called 
valvulas conniventes. These valvulse conniventes are continued 
down into the jejunum and ileum, but g-radually 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 
which is seen the aperture for the common bile duct and the 
pancreatic 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 through- 
out 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 mem- 
brane 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 



THE VISCERA. 181 

small, round, grayish bodies, in the mucous membrane, which 
have no duct and are called solitary g-lands. 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", g"ra3-ish patches, called Peyerian g-lands or Peyer's 
patches. They are twenty to thirty in number. Sometimes 
there are as many as forty. The long* diameter of these 
patches is in the direction of the long- diameter of the g-ut. 
They are made up of an ag-g-reg-ation of the solitary glands 
and become diseased in typhoid fever. 

The opening- of the small intestine into the larg-e is by 
means of a horizontal slit-like opening-, situated on the inner 
side of the larg-e intestine two and a half inches above its 
commencement, and g-uarded by a valvular arrang-ement called 
the ileo-coecal, or ileo-colic valve. This valve consists of two 
projections into the cavity of the large intestine, one above 
and the other below the button-hole-like aperture, each seg-- 
ment being- a fold of mucous membrane covering circular fibres 
of muscular tissue. 

The larg-e intestine, like the small, has four coats, external 
serous, internal mucous and, between these, two muscular, 
outer long-itudinal, inner, circular. From the commencement 
of the g-ut to the rectum the longitudinal coat is not distributed 
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 g-ut, and in conse- 
quence the other tunics are thrown into folds with correspond- 
ing- depressions. These prominences are known as the saculi 
of the larg-e intestine. Towards the termination of the colon 
these bands begin to be diffused, and in the rectum the long-itu- 
dinal fibres are ag-ain distributed and of equal length with the 
other coats. The mucous membrane, in consequence of the 
shortness of the long-itudinal 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. 



182 DESCRIPTIVE ANATONY. 

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 gfut until it 
reaches the point opposite the tip of the coccyx the second is 
the last inch of the g^ut, which here inclines backward to term- 
inate at the anus. The rectum presents the same four coats, 
in the same order, with the following- exceptions: The serous 
coat is a partial one, the upper half of the g-ut being- entirely- 
surrounded by peritoneum while the lower half is covered by 
it for only an inch at its upper front part, from which point it 
mounts to the bladder. The fibres of the long-itudinal muscular 
coat becomes much more distinct, and of a reddish color, in the 
lower part of the g-ut; 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- long-itudinal fibres while the mucous membrane lies 
between them and the cavity of the g-ut. These ascending- 
long-itudinal fibres are g-athered into separate bundles, or 
columns, which pass up for an inch or two before ceasing- 
and throw the mucous membrane into ridg-es with intervening- 
depressions called rectal pouches. Towards the lower extrem- 
ity of the rectum the fibres of the circular muscular coat are 
ag-g-regated into a thickened ring-, internal sphincter ani, and 
just above this the cavity of the g-ut is considerably dilated, 
forming- a capacious reservior in cases of long- continued 
constipation. 

The Liver. 

The liver stretches across the abdomen just beneath its roof, 
lying- in the right hypochondriac, the epig-astric and to some 
extent, the -left hypochondriac region. It is semi-ovoidal in 
shape, weig-hs 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 tingfe. It 
is, in structure, a solid glandular organ. For study it is divi- 
ded into an upper and a lower surface, an anterior and a pos- 
terior border, five ligaments and an excretory apparatus. 

The upper surface is smooth and convex, being- moulded on 
the lower surface of the diaphrag-m. It presents a gflistening- 



THE VISCERA. 183 

appearance due to the visceral layer of peritoneum, which has 
been traced. The peritoneum, passing- from the diaphragm to 
the liver in an antero-posterior fold, strikes the liver nearer 
the left than the rig-ht extremity. This fold, the long-itudinal 
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 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 just above the lower border of the ribs, though, 
when the liver is enlarged, it may be felt through the abdomi- 
nal parietes. 

The -posterior border is thick and rounded and marked b}" 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. 

The lozver surface is marked from before backwards by a 
fissure called the longitudinal, which is just opposite the 
longitudinal 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 at its pos- 
terior third. In this fissure are found the hepatic duct, to 
the right, and slighltly 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 intersec- 
tion of the transverse fissure, is called the venosus fissure, and 
the portion in front the umbilical fissure. The latter is fre- 
(juently crossed by a strip of liver tissue, called the pons 
hepatis. Lying in front of the transverse fissure, and produc- 
ing an impression on the lower surface of the right lobe, is 
the gall bladder; and between this and the longitudinal fissure 



184 DESCRIPTIVE ANATOMY. 

is a square-shaped portion of liver tissue called the lobus qua- 
ratus, whose limits are, in front, the anterior border of the 
liver, behind, the transverse fissure, to the rig-ht the g-all blad- 
der to the left the long-itudinal fissure. Behind the transverse 
fissure is another portion of liver tissue, which has received 
the name of lobus Spig-elii. It is three sided, having- in front 
the transverse fissure, to the left the venosus portion of the 
long-itudinal fissure and to the rig-ht the g-roove made by the 
inferior vena cava. 

Running- out to the rig-ht from the front of the lobus Spig-elii, 
just behind the transverse fissure, is a ridg-e, called the lobus 
caudatus. Near the posterior border there is a depression on 
the lov^er surface of the rig-ht lobe made by the rig-ht kidney 
and its suprarenal capsule. 

The liver is held in position by processes of peritoneum, 
called ligaments, which are five in number. 

The longitudinal, ox suspensory I ig-am en t consists of two lay- 
ers 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, with two exceptions, com- 
pletely invest it. One exception is the space on the lower sur- 
face, occupied by the g-all bladder, for the peritoneum leaps 
over the gall bladder, investing it, and leaves the contiguous 
surfaces of g-all bladder uninvested. The other exception is 
found at the posterior border, for the two layers here diverg-e, 
to form the rig-fit and left lateral lig-aments, which are nothing- 
more than the points where the visceral and parietal layers 
come in contact ; and between the two diverg-ing- layers, on 
the posterior border, there is a triang'ular space which has no 
serous coat. The two layers, as they skirt this space, are 
known as the coronary ligament. The fifth lig-ament is found 
as a rounded cord in the front edg-e of the longitudinal liga- 
ment. It is the obliterated umbilical vein. 

The excretory apparatus consists of a series of ducts, and a 
reservoir, called the gall bladder. 

The g-all bladder is a membranous pyrif orm sac, lying on the 
lower surface of the right lobe of the liver, its large end lying 



THE VISCERA. 185 

forward and usually fallino- short of the anterior border, 
thoug-h occasionally projecting- beyond it. Its small end lies 
backward and terminates at the transverse fissure in a neck 
which becomes 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 g^all bladder 
has three coats. The external serous coat is only a partial 
one, since it passes over the g"all bladder from the liver, leav- 
ing- 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 fissnre two ducts, one from the rig-ht and 
one from the left lobe, unite to form the hepatic duct, which 
is about two inches long- and descends to unite with the cystic 
to form the common bile duct — ductus communis choledochus 
— which descends for about three inches to open on a papilla 
on the lower inner part of the perpendicular duodenum. 

Structure. 

The external investment of the liver is the nearly complete 
serous coat. Beneath this is a white fibrous coat which every- 
where covers the liver, and g-ives off numberless processes 
which pass into the substance of the liver and divide it into 
minute subdivisions called lobules. These are made up of 
the proper liver substance. 

In the transverse fissure are three sets of vessels which 
ramify in the liver to fulfil the following- offices : 1st. The 
hepatic artery carries arterial blood to the liver. 2d. The 
portal vein also pours a stream of blood into the org-an. 3d. 
The hepatic duct, resulting- from the coalescence of the 
smaller ducts from the lobules, conveys the bile away from 
the liver. 

When traced into the liver these vessels are found associ- 
ated throug-hout the organ. The venous blood is removed 
from the liver by means of a fourth set of vessels called the 
hepatic veins, which result from ramifications associated 



186 DESCRIPTIVE ANATOMY. 

with the other vessels but which open, by three, or four sep- 
arate apertures, on the pDsterior border of the liver, into the 
inferior vena cava. 

The Pancreas. 

The pancreas is a pale, lobulated g-land. It is six or seven 
inches long" and varies in thickness from an inch and a half to 
less than half an inch. It weig-hs about three ounces and lies 
horizontally behind the stomach, with its large end or head 
embraced by the concavity of the descending- duodendum, 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 ante- 
rior is convex. The head is much the larg^er portion of the 
org-an and sends downward, at rig^ht ang-les to the rest of the 
organ, a considerable projection from which the g-land has 
been likened to a hammer. The head also furnishes a prom- 
inence backward and to the left which is sometimes called the 
lesser pancreas, and is found lying- behind the superior mes- 
enteric vessels. 

The Pancreatic Duct. 

The pancreatic juice is collected and conveyed away by a 
duct called the pancreatic, or canal of Wirsung; which com- 
mences in the tail of the org-an by a forked orig-in. The two 
branches soon unite and the resulting- duct, as it passes to the 
rig-ht g-rows by momentary accessions until it reaches the 
rig-ht extremity of the org-an, where it pierces the coats of the 
perpendicular duodendum 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 to retain it in position. The first is called the suspensory 



THE VISCERA. 187 

ligament and suspends the spleen by its upper extremity to 
the lower surface of the diaphrag-m ; 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 a 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 inter- 
nal, 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 vein eg'ress, 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. 

Structure. 

The spleen is invested by two coats, an external serous and, 
beneath this, a fibro-elastic coat, from the inner face of which 
are sent off processes, or trabecular, in the interspaces of 
which are found the proper splenic fissure or parenchyma, or 
splenic pulp. The spleen is a blood vascular, or ductless 
gland, and whatever it elaborates is carried off without the aid 
of a special apparatus. 

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 
some one-half an inch lower than the left. They about corre- 
spond to the twelfth dorsal and first 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 are the 
two supra-renal capsules. The kidney is about four inches 



188 DESCRIPTIVE ANATOMY. 

long", two broad atid one thick. It is peculiar in outline, 
hence the name reniform. The anterior surface is convex, the 
posterior, slightly flattened ; the upper end is the larger ; the 
outer border is convex, the inner, concave, and presents a deep 
depression, called the liilum 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 
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 external 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 viedullary ■por- 
tion. The inner portion is made up of conical masses called 
pyramids of Malpig hi ; they are arranged with their bases 
toward the cortical portion and their apices toward the hilum 
and are from eight to eighteen in number. ]j)ach pyramid 
consists of hundreds of straight tubules, leading from the cor- 
tical portion, where the urine is secreted, to the apex or papilla 
of the pyramid, where they discharge the urine. These pyra- 
mids are separated by prolongations of the cortical substance, 
which projects 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 infun- 
dihida, one infundibulum collecting the urine from each third 



THE VISCERA. 189 

of the org-an. Each infuudibulum, after a short course, 
subdivides into a number of short tubes called calices, each 
calyx terminating- by surrounding- the apex of one or more 
pyramids. The course of the urine, then, after secretion in 
the cortical portion is (1st.) through the uriniferous tubules, 
which form the pyramids of Malpighi (2d), dropping- from the 
apex or papilla it falls into (3d) the calyx, which uniting- with 
other calices from its third of the organ, forms (4th) an infun- 
dibulum, which combines with the other two infundibula to 
form (5th) the pelvis of the ureter, which (6th) contracts to 
the ureter proper which, lastly, opens into (7th) 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 col- 
umn to the brim of the pelvis, 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 leng-th 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, 
between these, an external long-itudinal and an internal circular 
muscular coat. This description applies to pelvis, infuudibu- 
lum and calyx. Near the bladder there is another layer of 
longitudinal 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 rag-ina in the female. Its 
shape, when distended, is ovoidal, or pyriform, the larg-e end 
being- below. When empty it is flattened against the pubes 
and is somewhat triang-ular. The direction of its long- axis is 
downward and backward. The capacity of the bladder is very 



190 DESCRIPTIVE ANATOMY. 

variable, thoug-h, in health, the urine is voided when half pint 
to one pint has been secreted. The upper third of the organ, 
about, is called the superior fiLudiis, summit or apex ; its 
middle third the body ; the lower third the base, or fundus. 
The channel throuo-h 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 g-land. In structure the bladder 
consists of the following- coats : 1st. The internal is mucous 
membrane. At the neck of the bladder there is a slight 
prominence, g-enerally absent, called the uvula vesicce, seen 
just at the commencement of the urethra. Between the uvula 
vesicce in front, as its apex, and the opening's for the ureters, 
as its posterior ang-les, there is a triangular space called the 
trigonum vesica, or triang-le of the bladder, whose base is 
formed by a line drawm between the opening's 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 ridg-e in the 
mucous membrane made by a bundle of long-itudinal fibres 
from the ureter. This space is by far the most sensitive part 
of the bladder, and corresponds to a similar space on the exte- 
rior of the base. 2d. The muscular coat is held to the mucous 
membrane by a layer of areolar tissue. It consists of long-itu- 
dinal and circular fibres, the long-itudinal forming- two layers 
between w^hich are found the circular. The circular fibres, 
at the neck of the bladder, are agg-reg-ated into a considerable 
mass, which by their tonic contraction, keep closed the opening- 
of the urethra. 3d. The external coat is serous and incomplete. 
In the male it covers the summit, sides, posterior 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 
traverses in seeking- an outlet from the body. It commences 
at the neck of the bladder and terminates at the meatus uri- 
narius, its opening- on the free extremity of the penis. Its 
leng-th is variously estimated, owing to the varying length of 



THE VISCERA. 191 

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 g-land to appear at its apex and become 
the second, or nicDibranoiis portion, which passes on to enter 
the bulb of the corpus spongiosum and become the third, or 
spongy portion. The spong-y 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 portion the remainder. 
The prostatic portion is the largest. 

The Prostate Gland. 

This gland is a small horse chesnut-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 breadth one and one-third, and its depth 
about one-half inch. It is invested in cellular tissue and has 
a proper fibrous capsule ; and it consists of interlacing unstri- 
ated 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, tvjo latcraldLud. an inferior, or isthnins. 
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 mon- 
tanum. 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 to fifteen minute 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 ejaculatory ducts, which 
pass back, one on either side, to two lobulated oblong bodies, 
one on either side, just behind the prostate gland, called 
seminal vesicles. 



192 DESCRIPTIVE ANATOMY. 



Seminal Vesicles. 

E^acli seininal vesicle is a reservoir for the seminal fluid, and 
is formed of a tube, about the size of a g-oose quill, five or six 
inches long-, coiled into an oblong- mass, which lies on the 
lower surface of the base of the bladder, its larg-e end project- 
ing 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, w^hose apex is at the prostate gland, which 
may be designated the intervesiciilar triangle. This space 
is devoid of peritoneum. The point where the peritoneum 
strikes the base of the bladder corresponds to the posterior 
boundary of this triang-le, whose sides are formed by the semi- 
nal 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, &c., which ascends to the upper 
border of the pubes, where it plung-es into the anterior abdom- 
inal wall, through the external abdominal ring-, then outward, 
along- the ing-uinal canal to the internal abdominal ring-, where 
it turns backward throug-h that ring- to enter the abdominal 
cavity. As soon as the cord enters the abdomen its various 
constituents disperse. The vas deferens passes to the upper 
part of the side of the bladder, thence down its posterior sur- 
face, along- the inner edg-e of the seminal vesicles, at the ante- 
rior extremity of which it is joined by the tube, whose 
convolutions form the seminal vesicles, and the two form the 
ejaculatory duct. 

The Ejaculatory Duet. 

The two ejaculatory ducts lie very near each other and pass 
forward and upward, throug-h the substance of the prostate 
g-land, for about three-quarters of an inch, to open on the sides 



THE VISCERA. 193 

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 cj^inders, two, lying- side by 
side called the corpora cavernosa^ and one in a g-roove between 
these known as the corpus spojigiosiim. When dissected out 
the corpora cavernosa are seen to commence by attachment to 
bone — the ischio-pubic rami — by a portion called the crus 
which terminates posteriorly in a pointed extremity ; while 
anteriorl}^ 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 beg^ins by a dilated portion called the bulb, 
situated between the crura, into which the membranous portion 
of the urethra passes to become the spong*y portion. It then 
passes forward, tunnelled by the urethra, 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 ridge beyond them. This dilated extremity is called the 
g-lans penis or head. The g-lans has its base backward, termi- 
nating- in a rounded edg-e, raised above the surface of the 
corpora cavernosa, 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 rela- 
tion, forward to the head, is called the body of the org-an ; 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 called the prepuce. On the lower aspect of the g-lans 
the prepuce is attached by a process, extending- forward to the 
meatus urinarius. This attached portion is called the fra^num. 

Passing- through the corpus spongiosum from the bulb 
behind to the meatus urinarius in front, is the spongy portion 

Des Anat — 13 



194 DESCRIPTIVE ANATOMY. 

of the urethra, which, just before its termination at the meatus, 
presents a considerable dilation called the fossa naviciilaris . 
The mucous membrane lining- the urethra presents many 
follicles, called lacunae, opening into the canal. When the 
mucous membrane reaches the meatus it is continued over the 
g-lans penis and the deep surface of the prepuce. 

The tissue of the three cylinders is that known as erectile 
tissue. E^ach 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 inter- 
lacing bands of fibrous tissue, the interspaces between which 
contain dilated blood vessels, which when turgid with blood, 
produce erection. The two corpora cavernosa, at the poste- 
rior 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 interruptions which have obtained for it 
the name of septum pecteneiform. 

The Testicles— Testes. 

The testicles are a pair of small org-ans whose function it 
is to secrete the semen. They are found suspended by the 
spermatic 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 : 1st, an external covering 
of skin ; 2d, beneath this a musculo-fibrous covering called 
the dartos ; 3d, 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 parietel, and that lining the testicle the 
/isceral layer. 

There are two cavities in the scrotum separated by a sep- 
tum from the dartos called septum scroti. There is a tunica 
vaginalis for each testicle. 



THE VISCERA. 195 

Structure of the Testicle. 

When the visceral layer of the tunica vag^inalis is removed 
we find beneath a bluish white fibrous investment of the 
testicle called the tunica albug-inea. This is much thickened 
at the back part, where it is called the mediastinum. 

Ivining- the inner aspect of the tunica albuginea is a reddish 
vascular investment called the tunica vasculosa. Lyinof on 
the posterior aspect of the testis is a flattened body called the 
epididymis, w^hich is made up of the convolutions of the tube 
conveying" away the semen . The upper portion of the epididymis 
is alone permanently connected w'ith the testicle, for it is here 
that the ducts, which transmit the semen from the testes, 
emero-e and unite to form the epididymis. The upper portion 
of the epididymis is called the g-lobus major, the lower portion, 
which terminates in the vas deferens, the g-lobus minor. The 
intermediate portion is called the body. The semen is secreted 
in w*hatare 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 hundreth of an inch in diameter, arrang-ed 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 toformasing-leduct, which, from its comparatively 
straig-ht course, is called the rectum. In the testis there are 
from twenty to twenty-five vasa recta, which plunge into the 
mediastinum and there unite to form from two to twelve ducts, 
which ascending- throug-h 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 vassa-efferentia, each of 
which is thrown into convolutions assuming- a conical appear- 
ance which are known as coni vasculosi and form the globus 
major. The bases of the cones terminate in large ducts which 



1% DESCRIPTIVE ANATONY. 

unite in the body of the epididymus into one duct whose convo- 
lutions, some twenty feet long, form the body and g-lobus 
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 
g-lobus minor, vas deferens. 

The JEiml Apparatus. 

The air reaches the lung-s from the throat throug-h a tube 
which has received different names in its various parts. It is 
first called the larynx, then the trachea, which, opposite the 
fifth dorsal vertebra, divides into the two bronchi. 

The Larynx. 

The larynx is formed upon a framework of separate carti- 
lag"es which require to be studied under individual names. 
These cartilag-es are as follows : 

Thyroid Cricoid 

Two Arytenoid Two Cornicula Laryngis 

E^pig-lottis Two cuneiform 

Thyroid Cartilage. 

The thyroid is the upper, the front and the larg-est cartilag^e 
of the larynx. In front it comes to an acute ang-le and produces 
the prominence, called the Adam's apple, pomum Adami. 
Prom this acute, or receding- angle, it passes backward and 
outward on either side in a quadrilateral plate called the ala 
of the thyroid cartilag-e, 

E^ach ala presents an internal and external surface, superior 
inferior and posterior border. The Outer Surface is slig-htly 
concave from above downward, wider above than below and 
marked by an oblique ridg-e, running from above downward 
and forward, terminating- at each end in a prominence, or 
tubercle. 

The hiternal Surface is nearly flat, slopes outward and 
backward from the receding- angle, and is slig-htly roug-hened 
for muscular attachment. 



THE VISCERA. 197 

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 back- 
ward to terminate in a prominent projection called the Supe- 
rior 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 supe- 
rior, 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 cornua, each terminated by a tubercle. The superior 
cornu is the longest. 

The inferior cor mi 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 is a ring and lies supporting the thy- 
roid, between whose inferior cornua it is grasped. It is nar- 
row 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 mus- 
cular attachment. Behind there is a similar ridge in the mid- 
dle 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 ^lo^e.'A 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 liiramentous attachment. 



198 DESCRIPTIVE ANATOMY. 

The Inferior Border is nearly straight, thick and rounded 
and sometimes marked by a deep notch. 

It is held by lig-aments to the first ring- of the Trachea. 
The interior of the ring is smooth and covered by mucous 

membrane. 

Arytenoid Cartilages. 

The arytenoid cartilages are found upon the cricoid, between 
the wings of the thyroid occupying the articular facets on its 
upper border. It is triangular in shape base below and apex 
above, and is divided into three surfaces, j)osterior, anterior 
and internal; three borders, external and two internal ; and 
two angles, anterior and external. 

The ^(9^/er2ory<:z<::e is concave for muscular attachment; the 
external is rough, while the internal is smooth and flat and 
faces its fellow of the opposite side. 

The two internal borders are inconspicious, forming the 
anterior and posterior boundaries of the inner face. 

The external border is rough and slopes upward, inward 
and backward . 

The external ang-le, points outward and backward and is 
rough and thick. It is called the muscular process. 

The anterior angle, thinner and longer, is know as the vocal 
process. 

The afex points upward and inward and is surmounted by 
a small cartilage, the cornicula laryngis. 

The base, directed downward, is concavo-convex for articu- 
lation with the similar facet on the upper border of the 
cricoid. 

The Cornicula Laryng-is are two small cartilages found 
perched upon the apex of the arytenoids. The cuneiform are 
small masses found in the aryteno-epiglottideau fold. 

Epiglottis. 

The epiglottis lies just above the receding angle of the thy- 
roid cartilage. It is leaf shaped, its apex downward and for- 
ward 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. 



THE VISCERA. 199 

It is covered by mucous membrane which holds it to surround- 
ing- 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 g-lands. 

Ligaments of the Larynx. 

The cartilag-es of the Larynx are held tog-ether by lig-aments 
some of which, like lig-aments at other articulations, serve 
only the purposes of such fibres ; while other so-called lig'a- 
ments are specialized bands employed in producing- sound. 

The hyoid bone lies just above the superior border of the 
thyroid cartilag-e and passing- between them is an unbroken 
membrane called the thyro-hyoidean, and in each of the poste- 
rior edg-es of this membrane a rounded cord, which passes 
from the superior cornu of the thyroid cartilag-e to the posterior 
extremity of the hyoid bone. 

The thyro-hyoid membrane is a thin sheet of fibrous tissue 
which is attached below to the upper border of the th3"roid 
cartilag-e, extending- from one cornu to the other and filling- in 
the notch above the ang-le. 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 cartilag-es are held tog-ether by the 
following- lig-aments. The extremity of each inferior cornu of 
the thyroid cartilag-e is held to the facet on the side of the cri- 
coid by a capsular lig-ament. 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 
edg-e, covered by mucous membrane, which posteriorly is 
attached to the anterior ang-le of the base of the arytenoid 
cartilag-e, forming- the lower, or true vocal chords. 



200 DESCRIPTIVE ANATOMY. 

When viewed' from above the vocal chords appear to be 
separate bands of elastic fibres, each arising- from the receding 
angle of the Thyroid and passing backward, diverging from 
its fellow, 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 liga- 
ment which holds the cartilages together, forming a concavo- 
convex 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, ex- 
tend 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 
receding angle of the thyroid by a narrow ligament called 
thyro-epiglottic. It is connected to the hyoid bone by a liga- 
ment called hyo-epiglottic, which is attached to the epiglottis on 
its front edge near its apex. The back of the tongue and the 
epiglottis 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 C2,lled the instrinsic muscles of the larynx. 

Crico-Thyroid Posterior Crico-Arytenoid 

Arytenoid Lateral Crico-Arytenoid 

Thyro- Arytenoid 

Crico-Thyroid. 

The crico-thyroid is a small triangular muscle lying on the 
side of the cricoid cartilag-e and partly covering the crico- 
thyroid membrane, which appearS'On the mid-line in the inter- 
val 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. 



THE VISCERA. 201 

Action — When the thyroid cartilage is fixed by the thj^ro- 
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. 

Posterior Crico- Arytenoid. 

The Posterior Crico-arytenoid arises from the depression 
on the posterior aspect of the cricoid cartilage and, passing 
upward, outward and forward, is inserted into the outer angle 
of the base of the arytenoid. 

Action — B\^ drawing on the muscular process, or outer angle 
of the arytenoid, it rotates that cartilage around a vertical axis, 
carr3'ing 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 ar3^tenoid forward, approxi- 
mating the vocal processes 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. 

Action — By drawing the arytenoid cartilages towards each 
other, it narrows the glottis. 

Thyro- Arytenoid. 

The 1 hyro-arytenoid arises from the receding angle of the 
thyroid cartilage just beside and external to the attachment 
of the vocal chorcls, and, passing backward, parallel with the 
vocal cord is inserted into the anterior angle of the base of the 
arytenoid cartilage. This muscle runs parallel wnth the true 
vocal chord, into which some of its fibres are inserted. 

Action — By drawing the muscular process forward, turning 
the vocal process inward and for wad, it narrows the glottis 



202 DESCRIPTIVE ANATOMY. 

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 laryng-eal nerve 
supplies the crico-thyroid. The inferior, or recurrent laryn- 
g^eal 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 g"o and 
leaving a triangular interval between them called the chink 
of the glottis, or rima glottidis; these ridges are produced by 
the inferior-thyro arytenoid ligaments, or true vocal chords. 
Reversing the larynx and looking into its cavit}" 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 up- 
per correspond to the superior thyro-arytenoid ligaments and 
are the false vocal chords. As they are much less prominent 
than the true cords, they cannot 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 lar^mx, and this space is continued 
up on the outside of the false vocal chords, between it and the 
wall of the larvnx for 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 



THE VISCERA. 203 

membrane extending* between the arytenoid and the epiglottis 
and containing- the pyriform sacculus laryng-is which runs up 
just internal to its outer wall. This space extends to the supe- 
rior thyro-arytenoid membrane. 

The second subdivision. is the space between the vocal chords 
and contains four opening-s, viz: one above, leading* from the 
upper to the middle compartment, — being- the space between 
the false chords and sometimes called iho. false glottis; — one 
below, the space between the true chords, called the g-lottis, 
and leading- into the lower compartment; and one on either 
side, being- the opening- into each laryng-eal pouch. The g-lot- 
tis is the triang"ular space found between the true vocal chords 
in front and between the two arytenoid cartilag-es behind. 

The lower compartment is simply the circular space enclosed 
by the cricoid cartilag-e, and would, therefore, be the means of 
establishing- communication between the Larynx, above, and 
the Trachea, below. 

Trachea. 

Succeeding- the larynx comes 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 cesophag-us, and terminates by dividing-, opposite the fifth 
dorsal vertebra, into the rig*ht 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 larg-est 
element is a number — fifteen to twenty — -of cartilag-inous 
ring-s, one lying- above the other. 

The flattening* posteriorly is due to the fact that each ring- is 
wanting- in its posterior third, thus leaving- this portion of the 
tracheal wall wanting- in cartilag-e. The ring-s are not in con- 
tact but are separated, and at the same time maintained in 
position by a fibro-clastic 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 



204 DESCRIPTIVE ANATOMY. 

the riug-s, over the interval left by their imperfection, the 
membrane is continued and is here strengthened by unstriated 
muscular fibres, both long-itudinaland transverse. The longi- 
tudinal are unimportant; but the transverse, passing- between 
the posterior extremities of the rings, can, by their contraction, 
diminish the diameter of the trachea. 

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, 
beneath 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 
extends from its origin to the inner surface of the lung, forming 
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 
antero-posterior ridge is found separating the two bronchi. 
This ridge lies nearer the left than the right side and in con- 
sequence a foreign body falling into the trachea is more likely 
to enter the right than theleft bronchus. The left bronchus 
is about two inches long, the right about an inch. In structure 
they exactly resemble the trachea. 



THE VISCERA, 205 

Lungs. 

The luno-s are a pair of organs found in the thoracic cavity, 
one on each side of the middle line, resting upon the diaphram 
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 fol- 
lowing 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 cen- 
tre of each lung on its inner face the root is seen to enter its 
substance. The root is made up of various elements, nerves, 
lymphatics, &c., but its chief constituents are the bronchus, 
pulmonary artery and two pulmonary veins. From behind 
forward, 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, veins. 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 
b}' the downward inclination and greater length of the left 
bronchus. 

Kach 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 center of the ob- 



206 DESCRIPTIVE ANATOMY. 

lique fissure and runs nearly horizontally forward to the ante- 
rior border, thus dividing- the rig-ht lung- into three lobes known 
as upper, middle and lower. In the left lung there are but two 
lobes, upper and low^er. The rig-ht lung- is slig-htly larg-er 
than the left, ow^ng- to the encroachment of the heart on the 
left lung-. The rig-ht, how-ever, is shortened by the rig-ht lobe 
of the liver, which bulg-es the diaphrag-m on that side, and the 
diif erence is in reality not g-reat — the right lung- w^eig-hing about 
twenty-tw^o and the left twenty ounces. 

The PleuraB. 

E^nveloping- each lung- and lining- the chest w^all is a serous 
membrane, one on each side. 

These tw^o membranes are the two pleurse. They are sepa- 
rate from each other and each forms a distinct closed sac for 
its lung-, one face of the sack lining the inner surface of the 
chest wall while the other completely invests the lung. In 
front, behind the sternum, the two pleura 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 continuous. From 
the front of the root, the pleura passes forward 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 becomes the parietal 
layer, \vhich 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 surfaces of the two 
layers secrete a small amount of liquid which renders the 
movements of the lungs in respiration easy. 



THE VISCERA. 207 



The Mediastinum. 



Between the opposing- surfaces of the pleurae and the sternum 
in front and vertebral column behind, there is a space, called 
the mediastinum. 

This space is of ver}^ irreg-ular 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 g-ladiolus in front to the lower border 
of the fourth dorsal vertebra behind. On either side would 
be the pleurae, containing- the lung-s. In this space lie the 
g-reat vessels spring-ing- from the heart and the aorta and the 
structures passing from the neck into the Thorax. 

The anterior mediastium is bounded in front by the sternum 
and lower costal cartilag-es 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 niediasthuim is the broadest part of the inter 
pleural space and contains the heart and pericardium. 

The -posterior mediastinum is irregularly triangular, being 
bounded in front by the pericardium and roots of the lungs, 
behind b}' the vertebral column and laterally b}' the pleural. 
It extends from the fourth dorsal vertebra downward and 
contains many important cords. 

The Heart. 

The heart is a hollow muscular organ found in the cavity of 
the chest, 13'ing 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 



208 DESCRIPTIVE ANATOMY. 

with its upper part or base, and thus maintain it in position. 
To render its movements free in the pericardium, that struct- 
ure 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 orig-iu of the vessels on one side to 
the same point on the opposite side. The portion lining- the 
pericardium is called the serous pericardium and the mem- 
brane which it lines the fibrous pericardium. The heart 
is conical in shape, its base being above and to the rig-ht 
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 posteriorly. Its weig-ht is from nine to 
twelve ounces, varying- in the two sexes and being- slig-htly 
larg-er in the male. 

The exact position of the heart is thus stated : the base lies, 
behind the sternum, corresponding- to a line drawn between 
the upper borders of the extremities of the third costal carti- 
lag-es ; the apex is downward and to the left, striking- the chest 
wall at the space between the fifth and sixth ribs, three to 
three and one-half inches to the left of the middle line, about 
opposite the g-ladio-xiphoid joint. 

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 posi- 
tion of this septum can be predicted by an inspection of the 
exterior of the heart, for it is marked by a g-roove passing- from 
the base anteriorly and to the left downward to the rig-ht of 
the apex to run along- the posterior aspect of the heart and 
terminate at the base, towards its rig-ht aspect. An artery is 
found lying- in this g-roove, which is called, for a reason here- 
after g-iveu, interventricular. From the position of the g-roove 
it is seen that the apex of the heart is formed entirely by the 
left half, the front of the heart mainly by the rig-ht half, while 
the back is the product, principally, of the left half. 

When the heart is laid open its entire cavity is seen to be 
lined by a serous membrane, continued into the vessels which 
communicate with it called the endocardium, and that each 



THE VISCERA. 209 

lateral half is subdivided by a partial horizontal septum into 
two cavities, the upper called the auricle, rig-ht or venous, and 
left, or arterial, the lower, the ventricle, rig-ht, or venous and 
left, or arterial. 

The position of the horizontal septum is indicated by a 
groove passing" around the heart called the auriculo-ventricu- 
lar. 

In the adult the venous blood of the entire body, with the ex- 
ception of that of the heart itself, is returned into the venous 
auricle by two g-reat veins called vena^ cavas, superior and 
inferior, the one bringing- the blood from the head and upper 
extremities, the other from the lower extremities and bod}^ 
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 throug"h 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 
bv its pulsation into the venous ventricle, with which it com- 
municates by an aperture througfh the horizontal septum called 
the venous auriculo-ventricular opening". From the venous 
ventricle 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 beg-in with the venous auricle. 

The venous miricle consists of two portions; the larg-er part 
is called the sinus, but, communicating- with this and project- 
ing- forward, is an ear shaped addition, called the appendix 
auricula; — 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 opening's a slig-ht 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- 

Des Anat — 14 



210 ~ DESCRIPTIVE ANATOMY. 

for the coronary sinus, g-uarded by a valve-like fold of endo- 
cardium called the coronary valve; on the septum between the 
two auricles, an oval depression, called the fossa ovalis, and 
surrounding- this, except below, a ridg^e called annulus ovalis; 
extending- along- the wall of the auricle from the opening- of 
the inferior vena cava to the fossa ovalis, is a ridg-e, the remains 
of the Eustachian valve of the foetus; the lining- membrane 
presents ridg-es caused by little muscular columns called 
musculi pectinati; the opening- throug-h the horizontal septum 
into the venous ventricle, and, lastly, foramia Thebesii. 

To sum up we have the following-: 1st, superior vena cava ; 
2d, inferior vena cava; 3d, coronary sinus ; 4th, foramina The- 
besii; 5th, venous auriculo- ventricular ; and six other appear- 
ances, viz: 1st, musculi pectinati ; 2nd, tubercle of Lower ; 
3d, coronary valve ; 4th I^^ustachian valve ; 5th, fossa ovalis ; 
6th, annulus ovalis. 

The venous ventricle has two opening-s 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 seg-ments of the valve 
are attached. To prevent regurg-itation of blood when the 
ventricle contracts, the opening- is guarded by a valve consist- 
ing- of three flaps, formed of folds of endocardium strength- 
ened 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 contracts, 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 columnse 
carnese and are divided into three sets arranged as foUow^s : 
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, 



THE VISCERA. 211 

terminatingf at the other in tendinous cords which are them- 
selves attached to the ventricular aspect of the segments of 
the valve and are only long- enouo-h to allow these to close with- 
out floatino- 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 aofain return to it were it not for a 
valvular arrang-ement here, called the pulmonary semilunar 
valve, which guards the orifice of the pulmonar}" artery. The 
semilunar valve is three segments arranged around the interior 
of the pulmonary artery, just at its commencement. Each 
segment is semilunar in shape, its convex border being at- 
tached w^hile the superior border is free and straight. They 
consist of folds of lining membrane, strengthened b}'^ 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 dilation of 
the artery, called sinus of Valsalva, and 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 : 1st, col- 
umnar carnear; 2d, chordae tendineae; 3d, venous auriculo-ven- 
tricular opening; 4th, opening into pulmonary artery; 5th, tri- 
cuspid valve; 6th, semilunar valve; 7th, foramina Thebesii. 

The arterial auricle has thicker walls than the venous, be- 
ing 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 auricula;; the arterial auriculo-ventricular open- 
ing; 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. 



212 DESCRIPTIVE ANATOMY. 

To sum up, we have 1st opening's for four pulmonary veins, 
2nd arterial auriculo-ventricular opening, 3rd musculi pectinati. 

The arterial ventricle 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, there- 
fore, 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 columns carneae much more prominent and more intimate- 
ly intersecting than in the venous ventricle, but similar to them 
in arrangement, viz : some attached throughout their length, 
some at each end and free in the middle, some attached at one 
end to the wall of the ventricle, while the others terminate in 
tendinous cords attached to the ventricular aspect of the bicuspid 
valve. The blood is forced from the arterial auricle into the 
arterial ventricle, 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 bicuspid, or mitral, and is arranged upon the same 
principle as the tricuspid, being made up of two segments at- 
tached 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 chorda? 
tending. 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 semiluna valve, which is in 
every way the counterpart of the pulmonary semilunar^ except 
in being larger and stronger, consist 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 semilunar. 

To sum up, there are in the arterial ventricle: 1st, columnae, 
earner; 2d, chords tendineae; 3d, arterial auriculo-ventricular 
opening; 4th, aortic opening; 5th, bicuspid valve; 6th, aortic 
semilunar valve. 



THE MUSCULAR SYSTEM. 213 



THE MUSCULAR SYSTEM. 

When an incission is made in any part of the body, the 
following- structures, from without inward, are met with: 1st, 
ski)i\ 2d, superficial areolar fascia whose existence allows the 
free movement observed in almost every part of the integ-ument. 
It consists of two layers, betw^een which is g-enerally found 
fatty tissue, varying- in quantity indifferent parts of the body; 
3d, beneath the superficial fascia, in some parts of the body, 
are found the muscles with their proper i?ivesti?ijy-/ascia; 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 g-ives off 
from its deep face partitions, which separate different g-roups 
of muscles. 

The function of muscles is to produce movement, most of 
them being attached to bone, some havin^r no bony attach- 
ment, 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 almost 
invariably found between the two extremities, otherwise no 
movement would occur when the muscle attempted to contract, 
so that, as a rule, those muscles, which lay hold of bone at 
at both extremities, are attached to different bones at either 
end. The two attachments of a muscle are spoken of, one as 
the nrii^in, the other as the insertion, the orig-in being- usually 
that attachment susceptible of the least motion, and as a rule, 
especially true of the limbs, the orig-in is the point nearest the 
body, or the mid-line of the body. The action of a muscle con- 
sists in the shortening of its leng-th, thus drawing the parts 
to which it is attached nearer, usually by movement of the 
part into which it is inserted. Some movements are two com- 
plex to be brougfht 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 g-enerally a muscle consists of two parts : the red 



214 DESCRIPTIVE ANATOMY. 

fibres, g-athered into bundles, fasciculi, forming- a coarse, or a 
fine muscle, and a white, toug-her, strong-er portion called its 
tendon. With few exceptions the tendon is found at the ex- 
tremities of the muscle, and, as it is so much strong-er, bulk 
for bulk, the tendon is much the smaller part of the muscle, 
thus economizing- space at the attachments. The portion of 
muscle between its tendons of orig-in 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 
following- facts : 1st, the position which it occupies ; 2nd, its 
shape ; 3rd, the direction of its fibres ; 4th, its attachments ; 
5th, its action ; 6th, the number of its points of orig-in. 

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 insig-nificant, and the 
recti which are long- and narrow. The abdominal wall con- 
sists of the following structures from without inward, viz : 
1st, integ-ument ; 2d, two layers of superficial fascia with fatty 
tissue interposed ; 3d, the external oblique muscle ; 4th, the 
internal oblique ; 5th, the transversalis ; 6th, the transversalis 
fascia; 7th, 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 
interlock, forming- a white line extending- from the ensiform 
cartilag-e 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 of the abdomen derives its name from 
the downward and inward direction of its fibres and from its 



THE MUSCULAR SYSTEM. 215 

position, being- external to another oblique muscle. It arises 
by eig-ht flesiiy, tooth-like processes or digitations from the 
anterior surfaces of the eight lower ribs. The upper five 
digitations interlock with similar processes of the serratus 
magnus, the lower three with the latissimns dorsi. From 
their origin the fibres pass downward and inward, the dig-ita- 
tions 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 pubes. That portion of the 
aponeurosis which extends from the anterior superior spinous 
process of the ilium to the spine of the pubes is called Poiiparf 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 pubes Poupart's 
ligament sends downward some fibres which are inserted into 
the pectineal line of the pubis, forming Gimberuar s lig-ameut, 
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 b}^ 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 inward 
at the crest of the pubes. The edges of the aponeurosis which 
form the sides of the ring are called its pillars, internal and 
external, the external being inserted into the spine of the 
pubes and the internal interlocking with the internal pillar of 
the opposite side over the front of the pubes. For a short 
distance the apex of the ring is obscured by some curved 
fibres called intercolumnar fibres. The external abdominal 
ring transmits in the male the spermitic cord and in the female 
the round licfament. 



216 DESCRIPTIVE ANATONY. 

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 a thin tendinous membrane, called the fascia lumbo- 
rum, from the spinous processes of the lumbar vertebrae, the 
anterior two-inirds of the middle lip of the crest of the ilium, 
and from the outer half of Poupart's lig"ament. 

The fascia lumborum terminates in fleshy fibres on the side 
of the abdomen, and those fibres spring-ing- from the crest of 
the ilium are also fleshy: these radiate somewhat, the general 
direction, however, being upward and inward, and are inserted, 
posteriorly, 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 pubes. By reason of the arched 
direction of these fibres there is a short space 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: 1st, the integument; 2d., two layers 
superficial fascia ; 3d, the aponeurosis of the external oblique; 
4th, transversalis fascia and the parietal layer of the perito- 
neum. The conjoined tendon descends just behind the external 
abdominal ring, so that at this point the wall is wanting in 
only one muscular element — the aponeurosis of the external 
oblique. 

Transversalis. 

The transversalis derives its name -from the horizontal 
direction of its fibres. It lies just beneath the internal oblique 



THE MUSCULAR SYSTEM. 217 

and is the deepest of the three broad muscles of the abdomen. 
It arises by means of an aponeurosis trom the transverse and 
spinous processes of the lumbar vertebrae, fleshy from the inner 
aspect of the cartilag-es 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 upper half of Poupart's lio-ament. 
The posterior aponeurosis becomes fleshy on the side of the 
abdomen and these fibres, being- reinforced by those which 
arise from the costal cartilag-es and crest of the ilium, pass 
forward, become aponeurotic and are inserted into the whole 
leng-thof 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 pubes. 

Rectus. 

The rectus abdominis derives its name from the straig-ht 
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 pubes ; as it ascends it 
becomes fleshy and broader and terminates by three digitations 
which are inserted into the fifth, sixth and seventh cartilag-es 
just beside the sternum. In the upper half of its course the 
rectus presents three or four tendinous intersections which are 
called linear transversaj. Before the aponeurosis of the exter- 
nal oblique has been removed, the outer edg-e of the rectus 
presents a curved ridg-e called linea semilunaris. 

The rectus as it ascends is enclosed between the aponeu- 
roses of the three broad muscles, and these form what 
is called its sheath. This sheath is complete in front 
for the whole leng-th of the muscle, but behind is 
v.-anting- 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 aponeurosis of the 



218 DESCRIPTIVE ANATOMY. 

external oblique and half the aponeurosis of the internal 
oblique ; while for the same distance behind it has the aponeu- 
rosis 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 
peritoneum separating it from the abdominal cavity. For its 
lower fourth, that is from the point midway between the um- 
bilicus 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 transver- 
salis fascia. Where the sheath ends behind it is curved and is 
called the fold of Douglas. 

Fyramidalis. 

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 rises from the front of the crest of 
the pubes 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 ex- 
tremities upward on the body. One External oblique, acting 
alone, would 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 obliquo. of one side may act in concert 
with the external oblique of the opposite side. The tra?is- 



THE MUSCULAR SYSTEM. 219 

i'e7'sales, acting- together, compress the abdominal contents 
backward and inward. The }-ecti, w^hen the lower attachment 
is fixed, draw the body downward; or, w^hen acting- from above, 
will draw^ the pelvis upward. The fyramidales are tensors of 
the linea alba. 

These muscles are supplied by the lower intercostal nerves 
and the ilio-hypog-astric. Blood is received from the lumbar 
low^er intercostal, deep epig^astric and internal mamuary. 

Diaphragm. 

1st. Definition and position — The diaphrag-m is the arched 
muscular septum between the tw^o cavities of the trunk, pre- 
senting- its upper convex surface as the floor of the thorax and 
its equally concave under surface as the roof of the abdomen. 

2nd. 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 per- 
itoneum and is in relation with the liver, spleen, stomach, 
pancreas and kidneys. 

3rd. 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 
internum, behind from the front of the vertebral column by 
two crura. 

4th. 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 
aperture, which would otherwise exist, between the thoracic 
and abdominal cavities being closed by other structures. 

ib) The origin from the inner surface of the ribs is by digi- 
tations which interlock with similar digitations of the transvcr- 
sulis abdominis. 

{c) The lig-ameiitum arcualum cxIcdiudi arches across the 
quadratus lumborum 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. 



220 DESCRIPTIVE ANATOMY. 

{d) The ligamentuni 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 rig-ht crus arises tendinous from the front of the 
bodies of the second, third and fourth lumbar vertebra. 

{/) The left crus arises tendinous from the front of the bod- 
ies of the second and third lumbar vertebse. It is smaller as 
well as shorter than the rig-ht. 

5th. 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 arrang-ed like a 
clover leaf, presenting a central, a rig-ht and a left leaflet, the 
tendon is therefore called trefoil or central tendon. 

The diaphragm is pierced by three large apertures which 
are for the transmission of the following structures, viz: 1st, 
descending- aorta ^ vena azyg-os major, thoracic duct and some- 
times the sympathetic nerve\ 2d, the ascending vena cava; 3d, 
(jesophag'us "ajoA ^neinnog-astric 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 vertebrae each crus gives off from its inner side 
a bundle of fibres which crosses obliquely to join the oppo- 
site 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 verte- 
bral column an opening which is known as the aortic. This 
opening is over the front of the bod}^ of the twelfth dorsal 
vertebra, 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 thej^ again unite. This is the oesophageal opening and 



THE MUSCULAR SYSTEM. 221 

is situated above and to the left of the aortic opening-, between 
it and the middle leaflet, and about opposite the tenth dorsal 
vertebra. 

The opening- for the inferior vena cava is to the rig-ht of the 
middle line, between the rig-ht and middle leaflets of the ten- 
dinous centre and about opposite the ninth dorsal vertebra. 

6th. Action — The diaphrag-m is a respiratory muscle and an 
ag-ent of expulsion. When it contracts, as it does eig"hteen to 
twenty times a minute, it descends, becoming- less arched and 
thus increasing- the size of the thorax while it decreases the 
size of the abdomen, thoug-h the latter is compensated by the 
bulg-ing- 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 diaphram relaxes it ag-ain ascends, thus lessen- 
ing- the size of the thoracic cavity. 

The diaphrag-m is supplied by the phrenic nerves. Blood 
vessels come from the internal mammary and the phrenic 
branches of the abdominal aorta. 

ftuadratus Lumborum. 

The quadratus lumborum is a quadrilateral muscle found in 

^he posterior abdominal wall, in the lumbar reg-ion lying- beside 

:he vertebral column. It is enclosed between the middle and 

anterior lamellae of the posterior aponeurosis of the trans- 

versalis. 

It arises from the last rib and descends, being- attached by 
its inner edg-e to the transverse processes of the lumbar verte- 
brae, to be inserted into the ilium and the Ilio-lumbar lig-ament. 

Action — It draws the vertebral column to one side, and acts 
as an expiratory ag-ent by drawing- down the last rib. It also 
acts as an inspiratory ag-ent by fixing- the last riband prevent- 
ing- the diaphrag-m from drawing- it inward. The two muscles, 
acting- tog-ether assist in flexing- the body; while either may 
bend the trunk to its own side. 



222 DESCRIPTIVE ANATOMY. 

The nerves and arteries are from the anterior branches of 
the lumbar nerves and arteries. 

Muscles of the Heck. 

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. 
Beneath this is the Platysma Myoides muscle, and, on remov- 
ing- this, we encounter the dee^ or investing' cervical fascia. 

This fascia is a dense membrane firmly attached behind to the 
spinous processes of the cervical vertebrse, where it blends with 
the orig-in of the muscles in that region, and completely encircles 
the neck. Below it in part is attached to the clavicle and sternum 
in part it blends with the deep fascia covering- the thoracic 
muscles while another portion passes into the thoracic cavity 
where it blends with the pericardium and the fascia support- 
ing- the g-reat vessels. Above it is attached to the lower jaw, 
covers in the parotid gland and g-ives off some bands consid- 
ered as ligaments. Like all investing-, or enveloping-, fascias, 
it divides into layers, or septa, which form sheaths for neig-h- 
boring muscles, vessels, nerves and other structures. 

Leaving the cervical spines in a sing-le layer, it splits to en- 
close the trapezius ; uniting, at the anterior border of that 
muscle to cover in the triang-ular interval between it and the 
Sterno-matsoid, the two layers ag-ain divide and form a sheath 
for the litter muscle, and, ag-ain uniting-, they pass forward 
as a single layer to the midline of the body in front, where 
the fascia of the opposite side of the neck blends with the one 
described. Of the numerous septa g-iven 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 ^re-tracheal fascia, and one which passes in 
front of the pre-vertebral muscles and is called the fre-verte- 
hral fascia. From the pre-tracheal and pre-vertebral facias is 
derived an important 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, 



THE MUSCULAR SYSTEM. 223 

subdivided into supra and infra-hyoid groups, or elevators 
and depressors of the h3'0id bone, nine. 

Superficial Group. 

Plat^'sma Myoides Sterno-Cleido-Mastoid 

Platysma Myoides. 

When the integ"ument and superficial fascia have been removed 
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 coverino- 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 fi.bres 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 on the side of 
the face and some continuing- to the ang-le of the mouth ; these 
last are joined by some accessory fibres which take their orig-in 
on the side of the face from the fascia covering- the masseter 
muscle. These fibres have been considered as a separate 
muscle called risorius Santorini or laug-hing- 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 laug-hing. 

Sterno-Cleido-Mastoid. 

The sterno-cleido-mastoid is the second muscle in the su- 
perficial g-roup and lies beneath the platysma between two 
layers of the deep cervical fascia. It is one of the most im- 
portant 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 varible. 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 of the temporal bone 



224 DESCRIPTIVE ANATOMY. 

and adjacent part of the superior curved line of the occipital.. 
Between its two origins there is a fissure which extends up- 
ward 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. 

Depressors of the Hyoid Bone. 

Sterno-Hyoid Sterno-Thyroid 

Thyro-Hyoid Omo-Hyoid 

These muscles are arrang-ed 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 sternum. 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 betw^een them much larger triangu- 
lar spaces than really exist. 

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 sterni and perhaps from 
the inner extremity of the clavicle or sterno-clavicular ligament, 
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, 6-/er;^a 
thyroid. It arises from the posterior surface of the manubrium 
and possibly from the cartilage of the first rib, and, ascending 
beside the middle line is inserted into the oblique ridge on the 
ala of the thyroid cartilage. Below it is often traversed by a 
tendinous intersection as is the sterno-hyoid. 

Thyro-Hyoid. 

The thyro-hyoid is a short ribbon-like muscle which con- 
tinues the course of the sterno-thyroid to the hyoid bone, and 



THE MUSCULAR SYSTEM. 225 

derives its name from its attachments. It arises from the 
oblique ridg-e on the ala of the thyroid cartilage and is inser- 
ted into the hyoid bone. Frequently some of the fibres of the 
sterno-thyroid are continued directly into this muscle. 

Omo-Hyoid. 

The oino-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 perhaps from the lig-ament stretched across 
the notch ; and passes forward, inward and slightly' upward 
until, beneath the sterno-cleido mastoid, it becomes tendinous, 
its posterior belly ceasing*. It then ag^ain becomes fleshy, 
forming- the anterior belly, and passes nearly upward but 
with a slig-ht inclination inward, to its insertion in the hyoid 
bone at the junction of its body and g-reater cornu. The cen- 
tral tendon is held down, so as to g-ive the muscle its curve, 
by a loop of fascia which is said to pass to the cartilag-e of the 
first rib. 

Action — The depressors of the h3^oid bone, as the name in- 
dicates, draw the hyoid bone do\vn. 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, mig-ht 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, pro- 
tecting- the larynx in swallowing-. 

Nerve supply from descending- noni. Arteries superior and 
inferior thyroid. 

Elevators of the Hyoid Bone. 

Dig-astric Stylo-Hyoid 

Mylo-Hyoid Genio-Hyoid 

Genio-Hyo-Glossus 

Digastric. 

The digastric, as its name indicates, is a double-bellied 

muscle. It is round in shape, curved in direction and found 

Des Anat — 15 



226 DESCRIPTIVE ANATOMY. 

at the upper part of the side of the neck. It arises fleshy from 
the digastric fossa of the temporal bone and passing- down- 
ward and forward, 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 and upward 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, after emerging from it, plays 
through a loop of fascia which binds it down to the hyoid-bone. 

Stylo-Hyoid. 

The siylo-hyoid is a small muscle found lying beside the 
posterior belly of the digastric and deriving its name from its 
attachments. It arises from the outer side of the styloid 
process of the temporal bone, and passing downward and 
forward is inserted into the hyoid bone. Just before its inser- 
tion 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, the greater portion of the mus- 
cle meets its fellow of the opposite side on the middle line, 
forming a raphe, while some of its posterior fibres are inserted 
into the hyoid bone. 

Genio-Hyoid. 

The genio-hyoid is a small muscle which slightly increases 
in size as it descends. It lies beneath the mylo-hyoid just be- 
side the middle line. Itarises from the inferior spina mentalis 
and passes backward and slightly downward to be inserted 
into the hyoid bone. 

Genio-Hy 0- Glossus. 

^\i^ §eni-hyo-gloss2is is a thin, radiating fan-shaped mus- 
cle. 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 



THE MUSCULAR SYSTEM. 227 

apex, some of its lower fibres being- inserted into the hyoid 
bone. This muscle lies close to the middle line beside its 
fellow. 

Action — The g-eneral function is that of elevation of the 
hyoid bone or depression of the lower jaw. The posterior 
bellies of the dig-astrics can carry the hyoid upward and back- 
ward, while the anterior bellies carry it upward and forward. 
The stylo-hyoid acts in concert with the posterior belly of the 
digastric. The posterior belly of one dig-astric, and the stylo- 
hj^oid draw the hyoid upward, backward and to the side of the 
muscle acting-. The mylo-hyoid acts like a swing* which by 
shortening its fibres can elevate the floor of the mouth. The 
posterior fibres can draw upward and forward the hyoid 
bone. The genio-hyoid pulls the hyoid bone, and with it the 
tongue, upward and forward. The g-enio-hyo-g-lossus may 
pull the hyoid upward, slightly, but its main function is in 
moving- the tongue, which it draws forward and upward. 

Xerves. Stylo-hyoid and posterior belly dig-astric by the 
facial, — g-enio-hyoid and g-enio-hyo-g-lossus by ih.Q hypoglossal ; 
mylo-hyoid and anterior belly of dig-astric 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 inferior 
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 trape- 
zius. 

This space. is subdivided bv the sterno-mastoid into k great 
a?ilc?-io}- a.nd 3. g real foslerior triang-le. The anterior trian- 
gle 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. Thit posterior tria)igle has its base below, formed by 
the clavicle. It is bounded in front by the sterno-cleido-mas- 
toid and behind by the anterior edge of the trapezius. 

ICach of these triangles is again subdivided into smaller ones. 
The anterior is divided into three : 



228 DESCRIPTIVE ANATOMY. 

1st. The inferior carotid triang-le, or triangle of necessity^ 
is bounded in front, by the median line ; behind, by the ante- 
rior marg-in of the sterno-mastoid ; above, by the anterior 
belly of the omo-hyoid. Its base is internal. 

2nd. The superior carotid triang-le, or tHang-le 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. 

3rd. The dig-as trie or suhmaxillary triang-le 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 ligastric. 

The g-reat -posterior triangle is subdivided into two : 

1st. The suboccipital triang-le has its base below. It is 
bounded in front by the sterno-mastoid ; behind, by the ante- 
rior edge of the trapezius ; below, by the posterior belly of 
the omo-hyoid. 

2nd. The subclavian triangle has its base below. It Is 
bounded above by the posterior belly of the omo-hyoid ; iu 
front, by the sterno-mastoid ; below, by the clavicle. It con- 
tains the subclavian artery and vein, hence its name, and the 
brachial plexus of nerves. In the posterior triangle the sub- 
divisions are made by the posterior belly of the omo-hyoid ; in 
great anterior triangle by the anterior belly of the omo-hyoid, 
and the two bellies of the digastric. 

The Scaleni Muscles. 

The two scaleni muscles form part of a group called f>rce~ 
vertebral. 

The two scaleni muscles are distinguished as scalenus anti- 
cits and posticus. A small portion of the scalenus posticus is 
sometimes 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 arterj^ 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, 



THE MUSCULAR SYSTEM. 229 

fourth, fifth and sixth cervical vertebrae by tendinous slips, 
which, uniting- as they descend, form the muscle. It is in- 
serted b}' a narrow tendon into the upper surface of the first 

rib. 

Scalenus Posticus. 

The scalenus posticus 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 between its tubercle and ang-le — 
and is the part sometimes called scalenus medius — while the 
other goes to the same point on 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. 

Prevertebral Group. 

Rectus Capitis Anticus Major Long-us Colli 

Rectus Capitis Anticus Minor Rectus Capitis Lateralis 

Rectus Capitis Anticus Major. 

This muscle arises from the anterior tubercles of the trans- 
verse processes of the third, fourth, fifth and sixth cervical 
vertebra by small tendinous fasciculi 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 mag-num. 

Rectus Capitis Anticus Minor. 

This is a small muscle lying- beneath the preceding- and fur- 
ther from the mid-line. It arises from the transverse process 
of the atlas and is inserted into the basilar process of the occip- 
ital, slig-htly external to the preceding-. 

Rectus Capitis Lateralis. 

This muscle belong-s properly to the lateral vertebral reg-ion 
and is an inter-transverse muscle. It arises from the trans- 
verse process of the atlas and is inserted into the jug-ular pro- 
cess of the occipital. 



230 DESCRIPTIVE ANATOMY. 

Longus Colli. 

This muscle might be appropriately described as three. One 
arises from the transverse processes 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 cervi- 
cal 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 indifferent regions. In some situations, as in the lumbar 
region, it usually contains a large amount of fat; in other por- 
tions 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 iovmin^ih.Q. vertebral aponeurosis. 
This fascia is attached to the spines and transverse processes 
of the vertebrai 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 tra-pezius arises from the superior curved line of the oc- 
cipital bone, from the posterior occipital protuberance and from 
the spinous processes of all the dorsal and cervical vertebrae. 
The fibres converge outward, some ascending obliquel}^, 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 the same as the origin of the deltoid. 



THE MUSCULAR SYSTEM. 231 

Extending' from the posterior occipital protuberance to the 
seventh cervical /ertebra, and attached to the intervening- 
spinous processes, is a fibrous cord called lig-amentum nuchas ; 
and it is in reality from this cord that the trapezius arises. 

Nearly the whole of the orig-in 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 latisshmis dorsi arises from the spinous processes of 
the lower four or six dorsal vertebrs, all the lumbar vertebrae 
and fhe spinous tubercles of the sacrum, from the p^osterior 
third of the crest of the ilium and by fleshy slips from the 
three or four lower ribs. The muscle is tendinous at its ori- 
gin except that part arising* from the ribs. As it passes up- 
ward and outward the fibres converg-e, become thicker and 
fleshy and passing- over the lower ang-le of the scapula, wind 
around the teres major to be inserted along- with it into the 
posterior bicipital ridg-e of the humerus. The tendon of the 
teres major is wider and extends further down on the humerus 
than that of the latissimus dorsi. 

Action — It carries the humerus downward and backward, 
rotates it inward, is an inspiratory ag-ent, and, when the 
humerus is fixed, as in climbing- or using- crutches, it moves 
the body forward. 

The trapezius is supplied by the spinal accessory and 
branches from the anterior divisions of the third and fourth 
cervical. The long- sub-scapular supplies the latissimus 
dorsi. 

Second Layer. 

Levator Ang-uli Scapula; Rhomboideus 

Levator Anguli Scapulae. 

The levator aiif^uli scapuhc arises by tendinous slips from 
the posterior tubercles of the transverse processes of the four 



232 DESCRIPTIVE ANATOMY. 

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 intersection of the spine with that border. 

This muscle draws the shoulder upward and inward, or, 
actino- from below, inclines the neck and head to that side, 
rotating" them at the same time. 

The nerve for the levator is from the anterior divisions of 
the third and fourth cervical. 

Rhomboideus. 

The rhoniboideiis 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 as far as the inferior ang-le. Some make two muscles 
of this, calling" the portion which arises from the cervical ver- 
tebra rhomboideus minor and that arising" from the dorsal ver- 
tebrae rhomboideus major. 

Action — It moves the scapula upward and backward, so as 
to bring" the two scapulae nearer tog"ether. 

Third Layer 

Serratus Posticus Superior Serratus Posticus Inferior 

Splenius 

Serratus Posticus Superior. 

The serratus -posticus superior 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 ang"les. 

Action — It is an inspiratory agent. 

Serratus Posticus Inferior. 

The serratus posticus inferior has a tendinous orig"in from 
the spinous processes of the last two dorsal and first two lum- 
bar 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 expiratory agfent. 



THE MUSCULAR SYSTEM. 233 

Splenius. 

The sploiins arises from the spinous processes of the four 
lower cervical vertebrae and four or six upper dorsal vertebras. 
It ascends and divides into two portions, one, known as the 
spioiiKs 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 posterior tubercles of the transverse processes of the 
three upper cervical vertebras. 

Action — It bends the head and upper part of the spine back 
and rotates the head toward its side. 

Erector Spinae. 

This powerful muscle occupies a larg^e portion of the vertebral 
^•roove, extending- from the sacrum upward until its prolong-a- 
tions may be traced throug-h the cervical reg^ion. It is held 
down in position, throug-h a larg-e portion of its course, by 
the powerful vertebral aponeurosis, call by different names in 
the different reg-ions. In the lumbar region, where it is most 
powerful, it is continuous with the aponeurosis forming- the 
sheath of the quadratus lumborum. 

The erector spincc arises by tendinous fibres from the back 
of the sacrum, occup^ang- the whole of the sacral groove ; 
from the posterior part of the crest of the ileum : from the 
great sacro-sciatic ligament and from the spinous processes 
of the lumbar vertebrae. This larg-e 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 lonn-issiiims dorsi which is inserted into the transverse 
processes of the dorsal vertebras and into nearly all the ribs, 
this portion of the insertion being- very variable. Between 
these two divisions lies an accessory muscle, called musculns 
ucccssorius which, arising- from the ang-les of the six lower, 
is inserted into the ang-les of its six upper ribs. Continuing- 
this upward is the cervicalis ascendcus which, spring-ing- from 
the ang-les of the four upper ribs is inserted into the posterior 
tubercles of the transverse processes of the fourth, fifth and 



234 DESCRIPTIVE ANATOMY. 

sixth cervical vertebrae. In like manner the long-issimus dorsi 
is continued upward by an inner set of fibres the traiisversalis 
colli which spring's from the transverse processes of the six 
upper dorsal and is inserted into the cervical as hig-h as the 
second ; and the trachelo-mastoid which arises from the trans- 
verse processes of the dorsal vertebrae from the second to the 
sixth is inserted into the mastoid process. 

Beside these there are two small muscular masses, the spi-- 
nalis dorsi, in the lumbar, and spinalis colli in the cervicaj 
regfion which spring* from the transverse processes below and 
are inserted into those above. They are really part of the 
attachment of the long-issiumses dorsi. The complexus is a 
somewhat 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. 

The name almost sufficiently g"ives the action of the erector 
spin« — 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. 

This muscle is supplied by the posterior divisions of the 
spinal nerves in the cervical dorsal and lumbar reg-ions. 

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 spring-ing- from 
the spinous process of the axis and being- inserted into the 
inferior 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 edg-e of the sternum and from the costal carti- 
lag-es from the third to the sixth or seventh, and, passing* 
upiL'a7'd 3Lnd outzuard, is inserted into the second, third, fourth 



THE MUSCULAR SYSTEM. 235 

and fifth costal cartilag'es and corresponding' ribs. Its inser- 
tion corresponds to that of its antag-onist the serratus posticus 
superior. 

Action — It is an expiratory ag"ent. 

Intercostal 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. 

Anterior Thoracic Region. 

Pectoralis Major Pectoralis Minor Subclavius 

The muscles of this region are covered by the usual super- 
ficial fascia and by a deep fascia which partly blends with that 
of the cervical and, at the side, with that covering the axil- 
lary space. 

Pectoralis Major. 

The pectoralis Diajor 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 
structure, triangular in shape with its base within and apex 
without. 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, /. e. all of true ribs except 
the first and seventh (this origin being* by fibres which rein- 
force the muscle as it passes over the ribs) and from the 
aponeurosis of the external oblique muscle of the abdomen. 

The fibres converge as the}- 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 intermedi- 
ate fibres pass hori/.ontally outward. They all terminate in a 
folded tendon 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. 



236 DESCRIPTIVE ANATOMY. 

Action — It draws the humerus across the chest slig'htly 
rotating- the arm inward. If the arm be raised it will aid the 
latissimus dorsi in drawing- it downward, or, acting- from above 
in drawing- the body up^vard. Both it and the next muscle 
thus act as inspiratory ag-ents. 

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 larg-er size. It is found beneath the 
pectoralis major, is small in size, oblique in direction and tri- 
ang-ular 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 be- 
neath the clavicle. It is a small round muscle which arises 
from the cartilag-e, 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, 
beg-ins to be inserted, its belly being- extremely short, into 
the whole length of the g-roove on the under surface of the 
clavicle. This g-roove occupies about the middle one-third of 
the clavicle. 

Action — It draws the clavicle downward. 

Thoracic Surgical Triangle. 

Lying- just above the subclavius, which is sometimes g*iven 
as its upper limit, is a triang-ular 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 auxiliary 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 pecto- 
ralis minor. 



THE MUSCULAR SYSTEM. 237 

Lateral Thoracic Region. 
Serratus Magnus. 

The serratus mag-}ms is a larg-e thin muscle found upon the 
side of the chest wall. It derives its name from its extensive 
origin by means of diofitations or serrations. 

It arises by nine digfitations from the outer surface of the 
eight upper ribs, the lower five interlocking with serrations 
of the external oblique, and two arising from the second rib. 
Its origin is fleshy, and it continues its course, fleshy, outward 
and backward over the side of the chest, to be inserted into 
the whole length of the anterior edge of the posterior border 
of the scapula. 

Action — It moves the scapula on the thorax and, when the 
scapula is fixed, raises the ribs. 

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 Glu- 
teus Maximus of the lower extremity. Its base is directed 
upward and its apex downward. Its origin is extensive, con- 
sisting of musculo-tendinous fibres, which arise from the outer 
one-third of the anterior border of the clavicle, from the ac- 
romion process, 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 forward and downward, 
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 
central fibres, which act in concert with the supraspinatus, 



238 DESCRIPTIVE AN ATONY. 

the humerus is carried directly away from the body until it is 
at right ang-les with the body. 

The posterior circumflex nerve and the circumflex arteries 
supply this muscle. 

The Scapular Group. 

Subscapularis Teres Minor 

Supraspinatus Infraspinatus Teres Major 

The Scapular Grouf> of Muscles consists of the subscapularis, 
the supraspinatus , the infraspinatus , the teres major and the 
teres minor (L. Teres, long- and round). Three of these mus- 
cles, it will be seen, are named from the fossae w^hich they 
occupy upon the scapula, the other two being named from their 
supposed 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 unnec- 
essary 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 
fascia which invests the entire muscle, and from septa sent 
down from this fascia between the bundles of muscular fibre 
to seize the ridges of the subscapular fossa and from an aponeu- 
rosis which separates the teres major and form the long head 
of the triceps. 

These fibres converge, the superior one passing nearly directly 
forward and outward, the central ones having a slightly ob- 
lique direction upward, outward and forward, while the inferior 
fibres run nearly directly upward, outward and forward. It 
narrows to a tendon, thick and strong, which passes over the 



THE MUSCULAR SYSTEM. 239 

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 ligfament of the shoulder joint. 

Action. It is chiefly an inward rotator of the humerus; but 
its inferior fibres have a slig-ht effect in drawing- the humerus 
downward when it has been elevated, and carrying- it back- 
ward after it has reached the vertical position. 

Subscapular nerves and arteries supply it. 

Supraspinatus. 

The siiprasf>iiiatus rises from the whole of the supraspinous 
fossa, except its outer one-third, and from the interveniug- 
fascia, which completely covers the muscle. It is a triang-ular 
muscle, which converg-es as it passes forward and outward, 
forms a tendon which runs under the acromion process of the 
scapula, and which is inserted into the hig-hest of the three 
muscular impressions found on the g-reater tuberosity of the 
humerus, the lower fibres of the tendon blending- with the 
capsular lig-ament. 

Action. It aids the deltoid in raising-, or abducting-, the 
humerus until it is at rig-ht ang-les to the body ; and is to a 
slig-ht extent an outward rotator. 

Suprascapular nerve and artery supply it and the following- 
muscle. 

Infraspinatus. 

The Infraspinatus rises from the whole infraspinous fossa, 
execpt its outer third, from the investing- fascia, which covers 
the muscle, and from the inter-muscular septa sent down be- 
tween itself and the teres major below and the teres minor 
above near the axillary border of the scapula. Like its 
predecessor, the fibres converg-e to form a tendon, which 
passing- behind the shoulder joint, blends with the capsular 
lig-ament, and is then inserted into the middle of the three 
muscular impressions on the g-reater tuberosity of the humerus. 

Action. Its action is almost entirely confined to external 
rotation of the humerus. 



240 DESCRIPTIVE ANATOMY. 



Teres Minor. 

The teres minor rises from the upper two-thirds of the ax- 
illary border of the scapula, with the exception of the space 
occupied by the long- head of the Triceps. It also rises 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 di- 
rection is upward and outward. The tendon narrows but 
sligfhtly and after blending- wnth the fibres of the capsular lig- 
ament, is inserted into the lowest of the three muscular im- 
pressions on the g-reater tuberosity of the humerus, and into 
the bone for a short distance below. 

Action. Like its predecessor, its chief action is that of ex- 
ternal rotation of the humerus. 

Supplied by branch from the circumflex. 

Teres Major. 

The teres major lies just below the te^-es minor, from 
which, after its orig-in, it is separated by a widening- interval. 
It rises from the lower one-third of the axillary border of the 
scapula, and from that portion of the dorsum, called the infer- 
ior angle, which does not enter into the infraspinous fossa. 
' It also rises from the intervening fascia, which covers the 
lower portion of the muscle, and from inter-muscular septa 
between itself and the teres minor above and the infraspinatus 
below. From this origin it passes upward, outward 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 ridg-e of the humerus. 

Action. It draws the humerus downward and backward, 
acting- here in concert with the latissimus dorsi; and is also an 
inward rotator. Supplied by lower subscapular. 

Between the two teres muscles is a surgical triang-le of 
some importance, the base of which is directed towards the 
humerus, and the apex towards the scapula. This triang-le 
is bounded above by the lower border of the teres minor, be- 
low by the upper border of the teres major, and externally by 



THE MUSCULAR SYSTEM. 241 

that portion of the shaft of the humerus which intervenes 
between the teres muscles. This space is subdivided by the 
long- head of the triceps into an external quadrilateral and an 
internal triang-ular space. The triang-ular 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 
anteriorly by the long- head of the triceps. The quadrilat- 
eral space is bounded behind by the long- head of the triceps, 
in front 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 fascia, 
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, poste- 
riorly with that which invests the posterior scapular g-roup, 
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 ridg-e, and to the internal condyle of the 
humerus. The external inter-muscular septum is likewise 
attached to the external border, external condyloid ridge, and 
external condyle of the humerus. 

These inter-muscular septa not only serve to separate the 
anterior from the posterior groups; but they also g-ive a firm 
and unyielding orig-in to the various muscles of the arm and 
forearm. 

The Muscles of the Arm are divided into two g-roups : the 
Anterior and Posterior Humeral Groups. 

Anterior Humeral Group. 

Biceps Flexor Coraco-Brachialis 

Brachialis Anticus 

Des Anat — 16 



242 DESCRIPTIVE ANATOMY. 

Biceps. 

The biceps (Iv. bis, twice ; caput, head), as its name indi- 
cates, has a double orig-in, one called the "long-" and the other 
the "short" head. The short head arises by musculo-tendi- 
nous fibres from the coracoid process of the scapula, in common 
with the coraco-brachialis. It descends blended with this 
muscle for its upper two inches, and then no longer blended, 
but parallel, with the coraco-brachialis, to the insertion of 
that muscle, where it is joined by the lo^ig- head, which arises 
from the upper border of the g-lenoid cavity of the scapula, 
where it blends with the g-lenoid ligament. By tendinous 
fibres the long head passes over the shoulder joint in a sepa- 
rate 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 invest- 
ing fascia of the forearm, while the bulk of the tendon is 
inserted 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 trifling extent abduct the forearm, 
and the long head to some extent can adduct 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. The biceps is sup- 
plied by the musculo-cutaneous nerve. 

Coraco-Brachialis. 

The Coraco-brachialis, arises in common with the short 
head of the biceps from the coracoid process of the scapula, 
passes down on the inner 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 middle of the internal face of the shaft of the hmerus. 

Action. It is a flexor of the arm ; and can, acting in concert 
with the short head of the biceps, aid that muscle, though 



THE MUSCULAR SYSTEM. 243 

acting" more powerfully, in carrying- the arm inward, or ad- 
ductingf it. It is supplied by the musculo-cutaneous nerve. 

Brachialis Anticus. 

The Brachialis Anticus is a bulky mass lying- deeper than 
the preceding- muscles on the lower part of the front of the 
arm. It arises by two dig-itations, so arrang-ed 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 spring-s from the 
whole of the internal inter-muscular septum, and from the 
upper portion of the external inter-muscular septum, being- 
cut off from the latter by the orig-in of the supinator long-us 
and extensor carpi radialis long-ior. It narrows to a triang-u- 
lar tendon, which passes over the elbow, and is inserted into 
the front of the coronoid process of the ulna. 

Action. It is a pow^erful flexor of the forearm upon the 
arm, thoug-h in some positions of the body — ^as in "chinning-" 
a bar — it flexes the arm upon the forearm, acting-, as all mus- 
cles do, from either extremity. It is supplied by the musculo- 
spiral and musculo-cutaneous nerves. 

Posterior Humeral Group. 

Triceps. 

The tricefts is a larg-e fleshy mass. It covers the w^hole of 
the posterior face of the humerus, being the onh' 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 ^x'vryQ.^ from the upper one-inch of the axillary 
border of the scapula by tendinous fibres. 

The short head a.r\%c% from the inner one-half of the poste- 
rior face of the humerus, and the posterior face of the inter 
nal muscular septum and the intermediate arises from the ex- 
ternal half of the posterior face of the humerus, and the 
external inter-muscular septum. The three heads blend 
tog-ether to form the belly of the muscle, which passing- down- 
ward becomes tendinous, the tendinous fibres extending- much 



244 DESCRIPTIVE AN ATONY. 

further up on its posterior than on its deep, or anterior, aspect, 
to be ultimately inserted into the depressed surface on 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 pos- 
terior surface of the shaft of the humerus, the former begin- 
ning* 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 
passing over two joints, approximates the head of the humerus 
to the Glenoid cavity, and slightly aids other muscles in draw- 
ing the humerus backward. It may also in climbing draw 
the scapula, and if that be fixed, the body, upward on the 
humerous. 

It is supplied by the musculo spiral nerve. 

The Muscles of the Fore- Arm. 

Before reaching the muscles of the forearm we find that 
portion of the upper extremity enveloped in a strong fibrous 
membrane, called the Deep or Investing Fascia of the Forearm. 
This membrane 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 
attached 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 not only serve the purpose of dividing the different layers 
from one another, but which also serve to give a strong and 
firm attachment to the muscles which belong to this portion 
of the upper extremity. Some of these muscles arise from 
the fascia as a strictly investing 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, 



THE MUSCULAR SYSTEM. 245 

SO that could a muscle be dissolved out without affecting* the 
fascia, it would be found to have its separate and distinct com- 
partment, 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 
A f/terior a.nd 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 extremity to the lower end and styloid process of the 
radius and by the other to the cuneiform and pisiform bones. 
It binds the tendons of the Extensor muscles down upon the 
bones, and it sends down septa which form six separate com- 
partments throug-h 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 styloid process of the radius ; by the other extremity 
it is attached to the pisiform bone, sending" off a process 
which becomes attached to the unciform process of the unci- 
form bone. 

The Muscles of the Forearm. 

The muscles of the forearm are divided into those on the 
front and those on the back ; and these are ag"ain subdivided 
by intermuscular septa into a superficial and deep g"roup on 
the front of the forearm, and into three g"roups — 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 €\\}\Q.x: Flexor o^ Pronator, on the back either i5'.v/f^v^6^o?- 
or Supinator', and to these names are added the particular 
function of the muscle, as a Plexor of the radial side of the 
carpus or an Kxtensor of the radial side of the carpus. 

The Muscles of the Front of the Forearm. 

The muscles of the front are eig"ht in number and are di- 
vided into two layers, of which the superficial contains five 



246 DESCRIPTIVE ANATOMY. 

muscles and the deep three. The superficial muscles on the 
front of the forearm have a common tendon, the orig-in 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. 

Pronator Radii Teres. 

The Pronator Radii Teres is the first muscle of the super- 
ficial g-roup. It takes its origin from the internal condyle o f 
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 head, or 
deep head, of this muscle, which arises from the inner face of 
the coronoid process of the ulna, these two heads being sep- 
arated 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. 

Flexor Carpi Radialis. 

The Flexor Carpi Radialis is the second muscle of the su- 
perficial group. It arises from a 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 inclination outward for the upper one-third of the fore- 
arm. The muscular belly then changes into a tendon, which 
running vertically downward, passing through a groove in the 
trapezium, is inserted into the base of the metacarpal bone of 

the index finger. 

Palmaris Longus. 

The Palmaris Longus arises from 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 



THE MUSCULAR SYSTEM. 247 

forearm, soon becomes tendinous and is inserted into the pal- 
mar fascia chiefly, but partly into the anterior annular liga- 
ment. The muscle should be called the "middle flexor of the 
carpus. 

Flexor Carpi Ulnaris. 

The Flexor Carpi U/?iaris a.r\ses from the internal condyle, 
the investing- fascia, and the intermuscular septa between itself 
and the Flexor sublimisdigitorum. It also arises from the in- 
ner 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 fing-er, its tendons enclosing- the pisiform as a 
sesamoid bone. 

Flexor Sublimis Digitorum. 

The Flexor Sublimis Dig-itoruin lies beneath the preceding- 
muscles of the g-roup and is in contact with the investing- fas- 
cia for only a small portion of its course, frequently not touch- 
ing- that fascia at all. It arises from the inner condyle of the 
humerus, from the internal lateral lig-ament 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 anterior annular lig-ament, and then, 
separating- from one another, pass forward to each fing-er, to 
be inserted into the side of the shaft of the second phalanx of 
each of the four lesser fing-ers. At the base of the first pha- 
lanx, each tendon splits, and throug-h this opening- the tendon 
of the deep Flexor pisses. The superficial tendons then 
unite and form a g-roove, in which the tendon of the deep 
Flexor lies. They then split a second time to be inserted 
into the sides of the second phalang-es. 

Second or Deep Layer. 

Flexor Profundus Dig-itorum Pronator Quadratus 

Flexor Long-US Pollicis 



248 DESCRIPTIVE ANATOMY. 

The flexor profundus digitornm lies just beneath the subli- 
mis and to the ulnar side of the lon^us 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 ulna 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 tendon 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 long-its pollicis lies to the outer side of the preced- 
ing- 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 tendi- 
nous, 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 mus- 
cles for that distance. It arises from the inner side of the 
ulna, receiving 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. 

Nerve and Arterial Supply. 

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 fore- 
arm are supplied by the median nerve or one of its branches, 
except the Flexor carpi ulnaris and one-half of the Flexor 
profundis digitorum. The branch of the median which sup- 
plies the deep muscles is called the interosseous ; the nerve 
supplying the Flexor carpi ulnaris and the inner half of the 
Flexor profundus digitorum is the ulnar. 



THE MUSCULAR SYSTEM. 249 



Action of the Muscles of the Forearm. 

The name indicates the action of each of these muscles, but 
indicates onl}' 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 
becomes, in common with the other muscles of the g-roup, a 
flexor of the forearm upon the arm. 

The Flexor carpi radialis, Pahnaris loiigzis, and Plexor 
carpi iiluaris are primarily flexors of the wrist; but the pal- 
maris long-us in addition is a tensor of the palmar fascia, 
and all of the three flex the forearm upon the arm. 

The Flexor siiblimis dig-itoruni flexes the second phalanx on 
each of the four lesser fing-ers. 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 
forearm upon the arm. 

The Flexor longus -pollicis flexes the first phalanx of the 
thumb; then the second 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 dig-itorum flexes the first 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 l)etween the two bones. It econo- 
mizes weig-ht, while it furnishes as stable an orig-in for mus- 
cles as does bone. 

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 g-roups, each containing- four 
muscles, called radial, superficial and deep g-roups. These 



250 DESCRIPTIVE ANATOMY. 

muscles, are either extensors or supinators,, acting- in opposi- 
tion to those on the front of the forearm. 

Radial Group. 

Supinator Long-us Extensor Carpi Radialis 

Extensor Carpi Radialis Longior 

Brevior Supinator Brevis 

Supinator Longus. 

The supinator longus derives its name from the facts 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 condy- 
loid ridg"e and from the external inter-muscular septum, and, 
after descending- about two-thirds 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 long-ior 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 external 
inter-muscular septum, and descends to be inserted by its 
tendon into the base of the metacarpal bone of the index 
finger. 

Extensor Carpi Radialis Brevior. 

The extensor carpi radialis brevior^ deriving" its name from 
the facts stated with the preceding- muscle, arises from the 
common origin, which is the external condyle, the investing- 
fascia and an inter-muscular septum bet^veen 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 pollicis and extensor primii internadii poUicis, as 
does the preceding muscle, before reaching- the posterior 
annular ligament, then passes beneath the tendon of the exten- 
sor secundi internodii pollicis and is inserted into the radial 



THE MUSCULAR SYSTEM. 251 

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. 

Supinator Brevis. 

The siifiinator brevis is a thin flat muscle which encircles 
the upper third of the radius. 

It arises from the external condyle of the humerus, the 
external lateral and orbicular ligaments from the triangular 
depressed surface beneath the lesser sigmoid cavity of the 
ulna, and to some extent from the intermuscular septum 
between the deep and superficial groups. It winds around 
the radius and is inserted into the upper third of its oblique 

ridge. 

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 com- 
partment with the extensor indicis. On reaching the back of 
the hand the innermost 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 iendo?is. This expression means that 
opposite the metacarpo-phalangeal joint each tendon becomes 
narrower and receives the tendon of the lumbricales. Pass- 
ing 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 a slight band to 
the tendons of the little and middle fincrers. 



252 DESCRIPTIVE ANATOMY. 

Extensor Minimi Digiti. 

The extensor ininimi digiti is an offshoot of the common 
extensor and, as its name indicates, has for its function the 
extension of the little fing-er. 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 leng"th of the 
back of the little fing-er along" with the slip furnished that 
fing-er by the common extensor, after the manner of extensor 
tendons. 

This muscle is really an offshoot of the common extensor. 
Its claim to individuality is 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 (exter- 
nal condyle, investing fascia and the intermusular septa 
between itself and the extensor minimi dig-iti externally 
and the deep g-roup in front) and, by a strong- aponeurosis, 
which blends with that g-iving- origin to the carpal flexor, from 
the middle third of the posterior border of the ulna. The 
muscle remains 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 annular ligament, is inserted into the base of the metacar- 
pal bone of the little fing-er on its ulnar side. 

Anconeus. 

The anconeus is a small triangular muscle which arises by 
its apex from the external condyle of the humerus, and is 
inserted 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. 



THE MUSCULAR SYSTEM. 253 

Deep Group. 

The four muscles of this group lie beneath those of the 
superficial g-roup, and all arise from the interosseous mem- 
brane as one attachment. As indicated b}^ their names, they 
are all extensors, three being- appropriated by the thumb and 
one by the index fing-er. 

Kxtensor Ossis Meta- Extensor Primi Inter' 
carpi PoUicis nodii Pollicis 

Extensor Secundi Inter- 

nodii Pollicis Extensor Indicis 

Extensor Ossis Metacarpi Pollicis. 

The extensor ossis metacarpi pollicis 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 exten- 
sor carpi radialis lang-ior and brevior, and passing- throug-h 
the annular lig-ament, is inserted into the base of the metacar- 
pal bone of the thumb. 

Extensor Primi Internodii Pollicis. 

The extensor primi internodii pollicis arises from the radius 
for about its middle two fourths and interosseous membrane. 
After becoming- tendinous it follows the extensor ossis meta- 
carpi pollicis, lying" internal to that muscle, crosses the same 
tendons, passes throug-h the same 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 arises from the ulna 
for about its middle third and from the interosseous membrane. 
Its tendon passes throug"h a separate compartment in the 
annular lig-ament, crosses the tendons of the extensor carpi 
radialis lang-ior and brevior after passing- throug-h the annular 
lig-ament, and is inserted into the base of the last phalanx of 
the thumb. 



254 DESCRIPTIVE ANATOMY. 

Extensor Indicis. 

The extensor indicis arises from the tilna and interosseous 
membrane and is inserted into the whole leng-th of the back of 
the index fing-er, blending- with the tendon furnished that fin- 
ger by the common extensor. It passes through the annular 
ligament in a compartment common to it and the extensor 
communis digitorum. 

Action — The names of these muscles in a large measure 
indicate their action. A carpal extensor extends the hand and 
draws it to its own side. The radial and ulnar extensors, 
acting 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 supination 
that the supinator longus acts to produce supination. With 
the hand in full supination it becomes a pronator. It may 
also act as a flexor of the forearm upon the arm. 

The supinator longus and extensor carpi radialis langior 
are supplied by the musculo-spiral nerve ; the others by the 
posterior interosseous. 

The Muscles of the Hand. 

The central portion of the palm of the hand is depressed 
below the level of a prominence on either side, one, extending 
from the base of the little finger toward the wrist, called the 
hypothenar 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 forming 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 



THE MUSCULAR SYSTEM. 255 

from one side to the other, binding- down the tendons which 
pass beneath it, known as the anterior annular ligament. 

The muscles of the hand consist of two groups, the thenar 
and hj^pothenar groups, and four small muscles found in the 
depressed portion of the hand, called lumbricales. 

Thenar Group. 

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. 
{d) Flexion, in which the thumb is put in contact with the 
palp of any of the fingers. This is effected by putting in 
motion the metacarpal bone of the thumb by a muscle called 
opponens. {c) Extension, movement in the opposite direction 
effected by muscles on the back of the forearm, which have 
been described. 

Abductor Pollicis Flexor Ossis Metacarpi Pollicis. 

Flexor Brevis Pollicis Adductor Pollicis. 

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. 

The flexor of the metacarpal bone of the thumb, or the 
opponens pollicis, arises from the trapezium bone and anterior 
annular ligament, 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 trapezoid, os magnum and base of the metacarpal bone of 
the middle finger. It Is inserted into both sides of the base 
of the first phalanx of the thumb, its tendons of insertion hav- 
ing sesamoid bones in them. 



256 DESCRIPTIVE ANATOMY. 

Abductor Pollicis. 

The adductor -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 Abductor Minimi Digiti 

Flexor Brevis Minimi Digiti Adductor Ossis Metacarpi 

Minimi Digiti 
Palmaris Brevis. 

The palmaris brevis is a small pale muscle lying just beneath 
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 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, /. 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 
ligament, and is inserted into the base of the first phalanx of 
the little finger. 

Action — It is a flexor of the little finger. 

Adductor Ossis Metacarpi Minimi Digiti. 

The adductor ossis metacarpi 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 meta- 
carpal 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 MUSCULAR SYSTEM. 257 

Flexor Tendons of the Fingers. 

It has been seen that the tendons of the flexor sublimis 
dig-itorum split at the base of the fing-ers 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 thecal. 

Muscles 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. 

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. 

The muscles of the gluteal region, nine in number, are ar- 
ranged in three layers, each of which has a muscle called 
gluteus. 

It receives its nerve supply from the lesser sciatic. 

First Layer. 
Gluteus Maximus. 

T\\Q. g-luteus maxhmis 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 portion of the crest, from the poste- 
rior 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 outward to be 
inserted into the line leading from the trochanter major to the 
linea aspera and into the fascia lata. 

Des Anat— 17 



258 DESCRIPTIVE ANATOMY. 

Action — It is an abductor and outward rotator of the thig-h, 
a tensor of the fascia lata and steadies the pelvis on the femur. 

Second Layer. 

Gluteus Medius Gemellus Inferior 

Pyriformis Obturator Internus 

Gemellus Superior Quadratus Femoris 

Gluteus Medius. 

The g-luteus inedhis is partially covered by the g-luteus 
maximus. It arises from the anterior four-fifths of the crest 
of the ilium, from the dorsum ilii between the middle curved 
line and the crest and from the investing- fascia, which covers 
its outer front part. It is inserted into the outer part of the 
trochanter major. On its outer edg^e the muscle is continuous 
with the g-luteus maximus. 

Action — Its g-reatest 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 g-luteal nerve. 

Pyriformis. 

The j;)yriformis is a pear-shaped muscle. It arises within 
the pelvis by three fleshy slips interposed between the ante- 
rior sacral foramina from the first to the fourth and from the 
adjoining- part of the ilium. It escapes from the pelvis 
throug-h the g-reater 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 dig-ital 
pit. 

Action — It is an external rotator of the thigfh. 

The Gemelli. 

The gemelli are a pair of small muscles lying- one above 
and the other below the tendon of the obturator internus. 

^h.Q §emullu^ superior arises from the spine of the ischium, 
runs horizontally outward and is inserted into the digital pit 
of the trochanter major. 



THE MUSCULAR SYSTEM. 259 

The gemellus inferior arises from the tuberosit}^ of the 
ischium, passes horizontally outward and is inserted into the 
digfital 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, becoming tendinous, it escapes from the pelvis through 
the lesser sacro-sciatic foramen, and passing horizontally, out- 
ward, its tendon winding 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. 

duadratus Femoris. 

The quadratus femoris^ as its name indicates, is a square 
muscle which lies below the tendon of the obturator internus. 
It arises from the outer lip of the tuberosity of the ischium, 
and is inserted across the posterior inter-trochanteric line. 
Its insertion is rarely marked by the presence of the linea 
quad rati. 

Action — It is an outward rotator of the femur. These 

muscles are all supplied by branches coming directly from 

the sacral plexus. 

Third Layer. 

Gluteus Minimus Obturator Externus 

Gluteus Minimus. 

The g'luteus ini7iimus lies beneath the gluteus medius and 
maximus. It is a triangular radiated muscle which arises 
from 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 continuous with the gluteus medius. 

Action — It is an abductor and invjard rotator of the thigh. 
Acting from below it steadies the pelvis on the femur. 

It is supplied by the superior gluteal. 



260 DESCRIPTIVE ANATOMY. 



Obturator Externus. 

The obturator externus arises from the inner two-thirds of 
the outer surface of the obturator foramen 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. 

Femoral Region. 

The muscles of the thigh are arranged in four groups, viz: 
posterior, superficial, anterior and internal femoral groups. 
Investing the thigh, just beneath the skin and superficial fascia, 
is a strong , thick, fibrous membrane which descending to the 
knee, invests that joint and passes on to become the invest- 
ing 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 cov- 
ering 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 internal intermuscular 
septa. The external intermuscular septum lies between the 
anterior and posterior femoral groups, and gives origin to 
muscles of both groups. The internal, lies between the an- 
terior and internal groups, no septum being interposed between 
the internal and posterior groups. Above, this fascia is con- 
tinuous, on the front of the thigh, with Pouparts ligament, 
externally and posteriorly with the fascia covering the gluteal 
muscles, while internally it is attached to the tuberosity of the 
ischium and to the ischio pubic rami. Below it seizes the bony 
prominences around the knee joint and becomes, posteriorly, 
th.t popliteal fascia, which covers in the popliteal space. 

^ The fascia lata consists of layers between which are found 
three muscles of the thigh forming the superficial femoral 
group. 



THE MUSCULAR SYSTEM. 261 

Where the fascia covers the posterior femoral region it 
is thinner than in any portion of its course. 

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 semitendinosus for several inches. In 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 ijhole length of the outer lip of the body of the linea 
aspera and from 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 in- 
serted chiefly into the head of the fibula, but sends some fibres 
to the outer tuberosity of the tibia and to the fascia of the leg. 

Semitendinosus. 

The semitendinosiLS 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 "'g-oose./oot'" insertion. It is 
made up of three muscles, viz: semitendinous, sartorius and 
gracilis. 

Semimembranosus. 

The semimenibranosiLs 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 semitendinous to the inner 
side of the knee-joint and receives a three-fold insertion, viz: 



262 DESCRIPTIVE ANATOMY. 

into the Horizontal groove on the inner tuberosity of the tibia, 
into the j^ofliteal fascia and into the posterior lig-ament of the 
knee-joint. 

These three muscles are spoken of as the hamstring- muscles, 
the biceps being" the outer, the semimembranous and semiten- 
dinosus being- the inner. 

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 thig-h; but, in addition, the biceps has a slig-ht influence in 
rotating- the leg- outward and the others in rotating- it inward. 
After flexing- the leg- upon the thig-h, they can then extend the 
thig-h 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 
stooping-. 

The g-reat siatic nerve supplies the g-roup. 

Superficial Femoral Group. 

Tensor Vag-inae Femoris Gracilis Sartorius 

Tensor Vaginas Femoris. 

The tensor vag-incB femoris is a short flat muscle found lying- 
on the outer aspect of the thig-h 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, descends 
with an inclination backward and is inserted into the fascia 
lata about one-fourth down the thig-h. 

Action — It is a tensor of the fascia lata and aids in rotating- 
the limb inward. 

Sartorius. 

The sartoi'ius is the long-est 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 thig-h, descends vertically behind 
the internal condyle of the femur and then turns obliquely for- 
ward 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 



THE MUSCULAR SYSTEM. 263 

other two being- the semitendinous and gracilis. The sartorius 
is the most superficial at the insertion, then the gracilis and 
the semitendinosus is the deepest. 

Action — It flexes the thigh on the pelvis, the leg" on the 
thig-h 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 
edg-e 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 facia of the leg, /. e., it is an element of the "goose foot" 
insertion. 

Action — It flexes the leg on the thigh and aids in adducting 
the thigh. 

The tensor vaginae femoris is supplied by the superior glu- 
teal nerve ; the sartorius by the middle cutaneous ; the gracilis 
by the obturator. 

Anterior Femoral Region. 
Psoas Magnus Vastus Externus 

Iliacus Internus Vastus Internus 

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 internus and 
the triceps extensor cruris consisting of rectus femoris, vas- 
tus internus, and vastus externus. The last three are inserted 
by a common tendon, called the ligamentum patellai, 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. 

Psoas Magnus. 
The -psoas mag-nus is a long spindle shaped muscle lying 
beside the vertebral column and descending into the thigh. 



264 DESCRIPTIVE ANATOMY. 

It arises from the bodies and bases of the transverse processes 
of the last dorsal, and all the lumbar vertebra ; from the 
intervertebral disks between them and from tendinous arches 
attached to the bodies of the vertebrae, extending- from the 
upper lipped edg-e 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 pel- 
vis and, as it pass beneath Poupart's lig-ament, 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. 

Iliacus Internns. 

The iliacus internus arises from the whole of the iliac fossa, 
from the internal lip of the crest of the ilium, from the ante- 
rior superior spinous process backward, from the base of the 
sacrum, from the ilio-lumbar ligament and by a few fibres 
from the capsular ligament of the hip joint. 

The fibres converge to a tendon which, passing beneath 
Poupart's ligament, blends wnth that of the psoas magnus to 
be inserted 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 
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 



THE MUSCULAR SYSTEM. 265 

terminates in the belly of the muscle ; and that in turn 
terminates at the lower part of the thig-h in a strong- tendon, 
which is inserted into the upper end of the patella. The 
fibres of this muscle have a bipenniform arrangfement. 

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 intermuscular septum. 
This muscle is covered over by a powerful aponeurosis from 
which its fibres arise. At its orig-in from the linea aspera, 
and the external intermuscular septum, it is intimately blended 
with the vastus internus. Its fibres proceed in a sfeneral 
direction downward and inward thougfh the inferior fibres 
pass more nearly inward. It is inserted into the outer 
edg-e of the tendon of the rectus femoris and outer edgfe of the 
patella. 

Vastus Internus. 

The vastus internus arises from the whole of the shaft of 
the femur from the anterior intertrochanteric line downward, 
from the inner lip of the linea aspera, from the internal inter- 
muscular septum, from the external intermuscular septum and 
from a part of the external lip of the linea aspera, where it 
blends with the vastus externus. It is inserted into the inner 
edg-e of the tendon of the rectus femoris and inner edg"e of the 
patella. 

The orig-in 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 
external septa. 

It is inserted into the inner edg"e of the tendon of the rectus 
femoris and into the inner border of the patella. The crureus 
is here considered a part of the vastus internus. 

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 encloses the patella as a sesa- 



266 DESCRIPTIVE ANATOMY. 

moid bone and is inserted, as the lig-amentum patellae, into the 
lower part of the anterior tubercle of the tibia, a bursa being- 
interposed between the tendon and the upper part of the tuber- 
cle 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 nam'e indicates, is an extensor 
of the leg- upon the thig-h. The central portion, or rectus 
femoris, is also a flexor of the thig-h upon the pelvis ; or, acting- 
from below, of the pelvis upon the thigh. 

Internal Femoral Region. 

Pectineus Adductor Brevis 

Adductor Ivongus Adductor Mag-nus 

The muscles of this region are adductors of the thigh, that 
is, they carry the thigh towards or across its fellow, and 
consequently they must all arise near the middle line of the 
body. 

Pectineus. 

Th.Q ;pectmeus is .a flat thin muscle which arises from the 
pectineal line and triangle of the pubes and the outer face of 
Gmibei'naf s ligament. It passes downward and is inserted 
into the upper part of the line leading from the trochanter 
minor to the linea aspera. 

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 
arranged in three layers, the adductor longus, which lies on 
the same plane as the pectineus, in front, next the adductor 
brevis and last the adductor magnus. 

Abductor Longus. 

The adductor longus arises by a small, round tendon from 
the front of the pubes 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. 



THE MUSCULAR SYSTEM. 267 

becoming- tendinous in turn, are inserted into the middle third 
of the liuea aspera, the fibres blending with those of the other 
adductors. 

Adductor Brevis. 

The adductor brevis arises from the body and ramus of the 
OS pubis, just below the spine and between the gracilis and 
obturator externus. It passes downward, outward and back- 
ward, 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 ma§)ius arises from the 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 cond3^1e 
of the femur. This muscle is pierced by five apertures, one 
above the other, which transmit branches of the femoral arter3^ 
The lowest is much the largest and transmits the termination 
of 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 power- 
ful outward rotators. The adductors are supplied 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 
ligament, its apex the intersection of the sartorius and the 
adductor longus. Entering this triangle at the middle of its 



268 DESCRIPTIVE ANATOMY. 

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. 

Muscles of the Leg. 

The muscles of the leg- are divided into three regions, viz : 
1st, anterior tibial ; 2d, posterior tibial ; 3d, external or fibu- 
lar. 

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 the fascia, lata — forming- 
with it the popliteal fascia — behind. Below, it becomes at- 
tached to the bony prominences of the foot, forming- the ante- 
rior and two lateral aunular lig-aments. 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 g-roups 
and one between the peroneal and posterior groups. The 
third is a broad transverse septum passing- between the super- 
ficial and deep muscles on the back of the leg-. 

Posterior Tibial Region. 

The muscles in the posterior reg-ion are placed in two lay- 
ers, superficial and deep. 

Superficial Layer. 

Gastrocnemius Plantaris Soleus 

Gastrocnemius. 

The g-astrocncinius is the larg-e muscle which g-ives 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 thev descend, converg-e to form the lower lateral 
boundaries of the popliteal space, and unite to form the belly 
of the muscle along which a groove is confined for some dis- 
tance. The belly terminates just below the centre of the leg 



THE MUSCULAR SYSTEM. 269 

in a large tendon called the tendo Achilles, which is inserted 
into the lower back part of the posterior tuberosity of the os 
calcis. It is the larg-est tendon in the body. 

Action — It raises the heel, and continuing" to act, raises the 
foot. 

Soleus. 

The soleus is a large fleshy muscle lying- beneath the gas- 
trocnemius. 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 tendo Achilles. 

Action — Same as the gastrocnemius. 

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 tendo Achilles. 

Action — Same as gastrocnemius. 

The three muscles just described form the triceps surae. 
They are supplied by the internal popliteal nerve. 

Deep Layer. 

Popliteus Flexor Longus Digitorum 

Tibialis Posticus Flexor Longus Pollicis 

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 



270 DESCRIPTIVE ANATONY. 

surface of the fascia which covers it, is inserted into the tibi a 
above and as low down as the oblique or popliteal line on its 
posterior face. 

Action — It flexes and inverts the leg". It is supplied by the 
internal popliteal nerve. 

Flexor Longus Pollicis. 

Th.Q. flexor long-iis pollicis arises from the lower two-thirds 
of the fibula, except the last inch, and from the intermuscular 
septum. It descends behind the internal malleolus into the 
sole of the foot, crosses the tendon of the flexor long-us dig-i- 
torum and is inserted into the base of the last phalanx of the 
great toe. 

Action — It flexes the last phalanx of the great toe. 

Flexor Longus Digitorum. 

The flexor long'us dig-itoruin arises from the lower two- 
thirds of the tibia, except the last two or three inches, and 
from the intermuscular septum. It passes downward behind 
the internal malleolus, divides into four tendons, which are 
crossed by the flexor longus pollicis, and are inserted into 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 leng-th of the 
posterior surface of the interosseous membrane, from the ad- 
jacent edges of the tibia and fibula and from the intermuscular 
septum. It descends behind the internal malleolus and is in- 
serted into the tuberosity of the scaphoid bone and into the 
internal cuneiform bone. 

Action — It is an extensor and abductor 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 MUSCULAR SYSTEM. 271 

The Interosseous Membrane. 

The iuterosseous membrane is a strong- ligamentous membrane 
which passes from tibia to fibula and is attached to their ad- 
jacent edo-es, after the manner of the interosseous membrane 
of the forearm. On its posterior aspect it is entirely appro- 
priated 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 Kxtensor Longus Dig-itorum 

Kxtensor Proprius Pollicis 

Of the three muscles in this group two have four points of 
origin in common. These four points are as follows: 1st, 
outer tuberosity of the tibia ; 2d, investing fascia of the leg ; 
3d, intermuscular septum ; 4th; 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 cnneiform bone and into the base of the metatar- 
sal 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 loui^us di^^itoriini arises from the common ori- 
gin — outer tuberosity, investing fascia, intermuscular septum 
between itself and the tibialis anticus internally and the pero- 
neus longus externally, and the interosseous membrane and 
from the head and whole length of the anterior aspect of the 
shaft of the fibula. It descends and divides into five tendons, 
which pass beneath the anterior annular ligament and are in- 



272 DESCRIPTIVE ANATOMY. 

serted 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 tendons. 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 some- 
times 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 tendon 
which passes beneath the anterior annular ligament and is in- 
serted 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 ligament- 
ous band which binds the tendons of the three preceding mus- 
cles down on the front of the 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, at- 
tached above to the inner malleolus and below to the lesser 
process of the os calcis which forms the swing ligament con- 
taining 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 

Peroneus Longus 

'^\\.^ -peroneus, or fihularis, 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 intermuscular 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> 



THE MUSCULAR SYSTEM. 273 

terminates in a tendon which passes behind the external mal- 
leolus, through the louver 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 of the foot. 

Peroneus Brevis. 

The fieroiieiis, or Jibularis, 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 fib- 
ula and from the intermuscular septum, descends behind the 
external malleolus, throug-h the upper groove on the outer sur- 
face of the OS calcis, and is inserted into the base of the meta- 
tarsal bone of the little toe. 

Action — It extends the foot. 

The two peronei muscles, as they are passing the outer 
malleolus, 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 
membranous. Above it is continuous with the anterior annu- 
lar ligament, 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 the plantar fascia. The iutcDial cDinular ligament 
is attached to the internal malleolus above and to the inner face 
of the OS calcis below. It forms grooves for the passage of 
the flexor tendons. 

The external amuilar ligament is attached to the internal 
malleolus and to the outer margin of the os calcis forming 
grooves for the peroneal tendons. 

Dorsum of the Foot. 
Extensor Brevis Digitorum. 

The extensor brevis digitorum arises from the upper and 

Des Anat— 18 



274 DESCRIPTIVE ANATOMY. 

outer aspect of the os calsis 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 
beneath this a strong fascia called iho. plantar fascia. It con- 
sists 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 accordance with the subdivisions of the plantar 
fascia, viz : a central 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 aud two lateral portions. 

In describing these muscles, however, they are taken in 
layers, of which there are three. When the plantar fascia, 
the dissection of which is the first step, has been removed, 
the first layer, consisting of one muscle in each group, is ex 
posed. This constitutes the second view in the dissection of 
the sole. 

First Layer. 

Abductor Pollicis Abductor Minimi Digiti 

Flexor Brevis Digitorum. 

The three muscles forming the first layer have a common 
origin, viz; 1st, the under surface of the os calcis; 2d, the 
plantar fascia which covers them; 3d, the intermuscular septa 
'which separate them. Some of the plantar fascia should be 



THE MUSCULAR SYSTEM. 275 

left on the muscles in dissecting- them, since it is a part of 
their orig-in. 

Abductor Pollicis. 

The abductor pollicis is the innermost of the three muscles 
of the first layers. It arises from the common orig-in and is 
inserted into the inner side of the base of the first phalanx of 
the g-reat toe. 

Its name indicates its action. 

Abductor Minimi Digiti. 

The abductor minimi dig-iti is the outer of the three muscles 
in the first laj^er. It arises from the common orig-in and is 
inserted into the outer side of the base of the first phalanx of 
the little toe. 

Its name indicates its action. 

Flexor Brevis Digitorum. 

Th^ flexor brevis dig-itoruin lies in the centre of the first 
layer. It arises from the common orig-in, passes forward and 
divides into four tendons for the four lesses toes. Each ten- 
don splits to allow the passag-e of the tendon of the long- flexor 
and is inserted into the sides of the shaft of the second pha- 
lanx. 

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 independ- 
ently of the other, but throws the part to which it is attached 
into slig-ht motion. 

Musculus Accessorius. 

The musculus accessorius arises tendinous and fleshy from 
the under surface of the os calcis and passing- forward is in- 



276 DESCRIPTIVE ANATOMY. 

serted into the outer side and upper surface of the tendon of 
the flexor longfus dig-itorum just as it splits into its four 
branches. 

Action — It corrrects 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 
long-us dig-itorum, while the fourth spring-s 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 long-us dig-itorum. 

Third Layer. 

Flexor Brevis Pollicis Flexor Brevis Minimi Digiti 
Adductor Pollicis Tranversus 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. 

'X:\iQ fiexor brevis -pollicis arises from the cuboid bone, the 
external cuneiform bone and the expanded tendon of the tibi- 
alis posticus. It is inserted into both sides of the base of the 
first phalanx of the g-reat toe, each tendon having- a sesamoid 
bone in it. 

Adductor Pollicis. 

The adductor pollicis arises from the cuboid bone, from the 
sheath of the tendon of the peroneus long-us 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. 

'X:\iQ flexor brevis minimi dig-iti arises from the base of the 
fifth metatarsal bone and is inserted into the outer side of the 
first phalanx of the little toe. 



THE MUSCULAR SYSTEM. 277 



Transversus Pedis. 

The ti'ansversus pedis arises by slips from the heads of the 
four outer metatarsal bones, and passing- inward is inserted 
into the outer side of the base of the first phalanx of the gfreat 
toe. 

Action — It is an adductor of the gfreat toe. 

Interosseous Muscles. 

Lying" between the metacarpal bones of the hand and the 
metatarsal bones of the foot are certain small muscles called 
from their position interosseous. In each member there are 
seven of these muscles, four dorsal and three plantar. They 
are bipenniform muscles, arising- from the metacarpal or met- 
atarsal bone and inserted into the first phalanx. The first 
dorsal interosseous of the hand is much larg-er than the others 
and is called the abductor indicis. 

The Muscles of the Face. 

The muscles of the face are arrang-ed in g-roups, viz: those 
connected with the orbit, with the nose, the mouth and, a very 
unimportant, g-roup connected with the auricle. 

Orbital Group — Three Muscles. 
Orbicularis Palpebrarum. 

The orhicularis-fxilpebrariiin is an elliptical muscle, 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 superior maxilla, while the other end bifurcates to be at- 
tached to the inner extremities of the tarsal cartilag-es. 

Kxternally the orbicularis palpebrarum is attached to the 
temporal fascia. 

Action — It closes the eyelids. - It is one of the sphincter 
muscles, but in its action differs from most of them in being" 



278 DESCRIPTIVE ANATONY. 

immovably attached at its extremities. When its fibres con- 
tract they bring" the eyelids togfetheJ 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. §-., the orbicularis oris, 
in the act of whistling-, since it has no bony attachment. 

Corrugator Supercilii. 

The corriigator supercilii is a small muscle, which arises 
from the inner extremity of the supercilliary ridg-e, 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., corrug-ates 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 

Cranial Group — One Muscle. 

Occipito-Frontalis. 

The occi^ito-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 
ag-ain becomes fleshy to be lost in the orbicularis palpebrarum 
and corrugator supercilii, its innermost fibres forming- the 
pyramidalis nasi muscle. 

Action — It raises the brows and throws the skin of the fore- 
head into wrinkles. 

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. 



THE MUSCULAR SYSTEM. 279 

Action — It draws down the inner extremity of the eyebrow 
and elevates the nose. 

Compressor Naris. 

The comf)ressor naris, triang-ular 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 are supposed to compress the nostrils. 

Depressor Alae Nasi. 

The depressor alee 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 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 g-roups, superior 
and inferior labial groups and one muscle, the orbicularis oris, 
which belong-s to both g-roups. 

Orbicularis Oris. 

The orbicularis oris is the sphincter muscle of the mouth ; 
as it has but slig-ht connection with bone, this attachment may 
be disreg-arded. It consists of two seg-ments, one in each lip, 
which meet at the ang-les of the mouth. 

Action — It can close the mouth in two ways, either by bring- 
ing- the lips tog-ether in a horizontal line or by approximating- 
the ang-les of the mouth at the same time. 

Superior Labial Group — Five Muscles. 

Levator Labii Susperioris Alaeque Nasi. 

The levator lahii susperioris alceque nasi arises from the 
nasal process of the superior maxilla and descending- divides 
into two slips, one of w^hich is inserted into the ala of the nose 



280 DESCRIPTIVE ANATOMY. 

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 ang'uli oris, or canine muscle, arises from the 
canine fossa of the superior maxilla and passes downward and 
outward to be inserted into the ang-le of the mouth. Its name 
indicates its action. 

The Zygomatic Muscles — Two. 

The zygomatic are two small muscles which arise from the 
Z3'g"omatic process of the malar bone and pass downward and 
inward. The zygomaticus major, the lower one, is inserted 
into the ang-le of the mouth and the zygoniaticus minor into 
the upper lip. 

Action — They carry the angle of the mouth upward and 
outward. 

Inferior Labial Group — Three Muscles. 

Q,uadratus 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 triang-alaris or depressor ang-iili 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 MUSCULAR SYSTEM. 281 

The Ocular Group. 

Levator Palpebrae Superioris 
Superior Rectus Inferior Rectus 

External Rectus Internal Rectus 

Superior Oblique Inferior Oblique 

The muscles forming this group are found within the orbit. 
All of them, except the levator palpebral superioris, are 
attached to the eye-ball, and all, except the two oblique mus- 
cles, arise at the apex of the orbit and pass forward flat, 
straight and widening as the}" 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 
distinguished as : 1st, superior rectus, because it lies above 
the eye-ball and draws the front of the eye upward ; 2d, infe- 
rior rectus, because it lies below the eye-ball and draws its 
front downward ; 3d, external rectus, because it lies external 
to the e3"e-ball and draws its front outward ; 4th, internal rec- 
tus, 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 difiFer but slightly in 
size and length. 

Levator Palpebrae Superioris. 
Lying just beneath the orbit, and between it and the superior 
rectus, is a muscle closely resembling the recti called levator 
f)alpchr(c superioris since its action is to raise the upper lid. 
It arises from the upper margin of the optic foramen and 
sheath of the optic nerve, passes forward and is inserted into 
the upper edge of the superic^r tarsal cartilage. 



282 DESCRIPTIVE ANATOMY. 



Inferior Rectus. 

The inferior rectus arises from the lower margfin 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. 

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 sur- 
face of the sclerotic coat about one-fourth of an inch behind 
the circumference of the cornea. It is important to remember 
its forked origin, since many nerves pass through the interval 
between its head. 

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 supsrior maxilla, near the inner 
side of the orbit. It passes out beneath the eye-ball and 
inferior rectus to be inserted into the sclerotic near the entrance 
of the optic nerve, on the outer 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, 



THE MUSCULAR SYSTEM. 283 

becoming- tendinous, it plays throug-h a cartilaginous ring- fixed 
to the fovea trochlearis : thence its tendon passes outward and 
backward, beneath the superior rectus, to be inserted into the 
outer aspect of the sclerotic about half way between the 
circumference of the cornea and the entrance of the optic nerve. 
Action — Its action is computed from the pully at the fovea 
trochlearis — hence it rotates the eye-ball on itsantero-posterior 
axis and draws it forward. 

Muscles of Mastication. 

Masseter Buccinator 

Temporal External Pteryg-oid 

Internal Pteryg-oid 

Masseter. 

The masseter arises from the zygfomatic process of the 
superior maxilla and from the anterior two thirds of the 
zygomatic arch by a bundle of fibres which pass downward 
and backward to be inserted into the ang-le 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 in- 
serted into the outer face of the ramus nearly to the basilar 
border of the bone. 

Action — The two muscles, acting- tog-ether, draw the lower 
jaw powerfully upward and press the teeth firmly ag-ainst the 
teeth of the upper. The superficial fibres draw the jaw 
forward while the deep 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 zyg-oma and forms the parotid fascia. 

Buccinator. 

The buccinator^ or trumpeter's muscle, is the bulkiest 
element of the cheek. It arises from the alveolar process of 
the superior maxilla, from the external oblique ridg-e of the 
lower jaw, as far forward as the second bicuspid tooth and 



284 DESCRIPTIVE ANATOMY. 

from the pterygo-maxillary lig-ament. Its fibres converge to 
be inserted into the ang-le of the mouth. 

Action^The buccinators compress the cheeks, keeping" food 
between the teeth or expelling air through the lips. 

The -pteryg-o-niaxillary lig-a7nent 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 
constrictor 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, 
shining aponerosis 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 con- 
verging, 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. 

External Pterygoid. 

The external pteiyjo-oid arises from the lower surface of the 
greater wing of the sphenoid, from the pterygoid ridge and 
sphenoidal spine and from the whole of the outer face of the 
external pterygoid plate. The fibres pass backward and out- 
ward 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 



THE MUSCULAR SYSTEM. 285 

forward and to the opposite side. It is the alternate action 
of the two muscles which produces the g-rinding- motion nec- 
essary for bruising* the food. 

Internal Pterygoid. 

The internal pterygoid, or internal mas seter 3X\^q^ from the 
inner face of the outer pterygoid plate, from the g*rooved 
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 pteryg*oid in grind- 
ing* the food. 

All the muscles of mastication are supplied by the muscular 
branches of the inferior maxillary division of the fifth, except 
the buccinator which also receives a branch from the facial. 
The internal maxillary artery furnishes blood. 



286 DESCRIPTIVE ANATOMY. 



THE VASCULAR SYSTEM. 

The Arteries. 

There are two sets of arteries: one the Pulmonary System, 
the other the Systemic System. The two systems communi- 
cate with one another. 

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 disminishing-in size 
until the capillaries are reached. Returning-, the blood passes 
throug-h the veins, which increase in size as we approach the 
heart. 

The Pulrnonary 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 chamber on the left, under 
side, the systemic circulation starts. E^ntering into the chamber 
above on the rig-ht 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 down into a 
cavity from which the pulmonary artery starts, this artery 
breaking- up into two branches and passing- to the lungs. Af- 
ter making- the circuit of the lung-s, 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 arteries all commence with the one g-reat trunk the aorta; 
but for several reasons we g-enerally begin with one of the 
arteries belong-ing- 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 g-reater than 
that of the original trunk. Similarly, if we consider the com- 
bined area of all the branches which spring- from any g-iven 
artery, we find that this area is infinitely g-reater than that of 
the orig-inal artery. On the other hand, the combined area of 
the veins, while larger than the combined area of the great 



THE VASCULAR SYSTEM. 287 

veins which return the blood to the heart, is much larg-er than 
the combined area of the arteries. Consequently, as the blood 
conti'nues its course in circulating" throug-h the body the rapid- 
ity of the current decreases in proportion as the distance from 
the heart increases. As the veins decrease in size, or contain- 
ing- capacity, as they approach the heart, the current becomes 
swifter; but never anything- like as swift as the current in the 
arteries. 

In describing- an artery, we not only g"ive the regfion 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 arter}-^; 
and there is usually something* else to be noticed, for instance, 
a tendon. Besides that, arteries have other covering's, skin 
and fascia; and other relations, which are neither cords, fascias 
nor muscles. Such, for instance, are the Thyroid gfland, the 
Trachea, the Pharynx, or the Thymus g-land. To describe 
one, for instance, let us take the g-reat vessel on the side of the 
neck, the Arteria Innominata. Starting* at the commencement 
of the transverse aorta, it passes upward and outward, and 
terminates in one of the most frequent ways in which arteries 
terminate, viz., by dividing- into two separate branches: one 
branch, the right common carotid, which runs nearly ver- 
tically upward in the neck, the other, the rig-ht subclavian, 
which apparently continues the course of the orig-inal vessel, 
with a slig-ht increase in its obliquity. There are two com- 
Dion carotids, di.xid.t'wo subclavians, rig-ht and left. To decide 
the difference between them, notice that the right common carotid 
and the rig-ht subclavian each pass down into the thoracic cav- 
ity. There is a combination of the two vessels on the right 
side; and no junction on the leftside, the right springing by a 
common branch, the left by separate branches. 

The Right Common Carotid. 

The rig-ht common carotid artery differs from the left in 
that it springs 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 differ- 



288 DESCRIPTIVE ANATOMY. ,*, 

ent from the relations of the right common carotid in this por- 
tion. The relations after they have passed from the thoracic 
cavity, and have reached the back of the sterno-clavicular ar- 
ticulation, become identical; and then the description of one 
vessel will apply to the other. 

The right common carotid commences b}'' being- one of the 
two terminal branches of the arteria innominata. It then 
passes upward witha slight inclination backward and outward, 
lying- upon the anterior tubercles of the transverse process of 
the four lower cervical vertebrae, about on a line drawn from 
the upper border of the thyroid cartilag-e. After reaching- that 
point, it terminates by dividing- into two branches, which are 
known as the internal and external carotid arteries. 

Covering- the vessel w^e find, first, the skin ; then a layer of 
superficial cervical fascia; then the platysmamyoides muscle; 
then the first layer of deep cervical fascia ; then the sterno- 
cleido- mastoid muscle ; then the second layer of deep cervical 
fascia. After pulling- that aside, we come to the sterno-hyoid 
muscle ; then to the sterno-thyroid ; and anterior belly of 
the omo-hyoid ; then to the last layer of cervical fascia ; 
forming- the front of the sheath of the vessel behind ^vhich 
you have the artery itself. 

It is more convenient to divide the vessel into two portions, 
the first portion being- considered as lying- in the "Triang-le of 
Necessity" or the inferior carotid tricDig-le, the second as lying- 
in the superior, or "Triang-le of l^lection". The first portion 
commences as the artery itself commences, as being- one of the 
branches of the arteria innominata, and terminates where the 
vessel is crossed by the anterior belly of the omo-hyoid. The 
second portion commences where the first terminates; and ex- 
tends to the termination of the artery at the upper border of 
the thyroid cartilage. The first portion is deeply seated, 
difficult of access; and the triangle is for that reason known as 
the Triangle of Necessity. Throughout the first portion the 
artery is completely covered by the sterno-cleido-mastoid mus- 
cles; it is only at its commencement that it is covered by the 
sterno-hyoid and thyroid, which rapidly draw away from the 
vessel and cease to be relations of it. Then as we pass up to 



THE VASCULAR SYSTEM. 289 

the seco?id portion of the vessel (the omo-hyoid being- the 
dividing" line, belongs partly to each portion), we find that the 
second portion is covered by superficial and deep fascia, 
plat3'snia myoides, and the sterno-cleido-mastoid, which in 
this situation overlaps rather than covers. Throug"hout its 
entire course it is covered by the sterno-cleido-mastoid and the 
platysma myoides; only at its beg^inning- is it covered by the 
bellies of the sterno-hyoid and sterno-thyroid; and only at the 
middle of its course is it covered by the omo-hyoid. 

The more important thing's to study in connection with the 
vessel are the cord relations, these being- always of g-reater 
importance than anything- else, owing- to the dang-er of wound- 
ing-. Every larg-e artery protects itself by passing- as closely 
as possible to the bone ; but another protection is the sheath, 
which is formed of fibrous tissue, in this case a part of the 
deep cervical fascia. So powerful is the sheath that many 
cases could be cited in which vessels have been found floating" 
in pus, the artery remaining- entirely uninjured. This vessel 
possesses one of the larg-est sheathes in the body ; and in the 
same sheath with it are found the internal jug-ular vein and 
the pneumog-astric nerve, all lying- upon the same plane, the 
artery being- most internal, the vein most external, and the 
nerve lying- between them. The nerve is sometimes described 
as "lying- between and behind" the vein and artery ; but this 
is not correct : It lies between them and not behind them. 
Another important structure running- downward upon its sheath 
is the Descendens noni, or Descendens hypog-lossi. This 
nerve passes downward on the front of the sheath of the com- 
mon carotid: and just before it reaches the upper border of the 
anterior belly of the omo-hyoid it receives one or two filaments 
from the cervical plexus of nerves forming-, just above the 
anterior belly of the omo-hyoid, Scarpa's Arch. In addition 
there is another important cord lying- just behind the artery, 
which has a larg-e bulg-e upon it near its upper extremity, called 
the cervical portion of the Sympathetic nerve. It descends 
upon the prevertebral g-roup of muscles directly behind the 
sheath. 

Des Anat— 19 



290 ^DESCRIPTIVE ANATOMY. 

On the upper portion of the course of the artery are g^enerally 
seen the superior thyroid veins, frequently two. In the lower 
portion, about its middle, are seen the middle thyroid gener- 
ally ; and below that gfenerally the anterior jug-ular, all of 
these veins being- superficial. At the commencement of 
their course these vessels are deeply seated, and covered by a 
larg"e number of structures ; and they are very close to each > 
other, the distance increasing- as we pass upward into the 
neck. Owing- to the projection of the Thyroid cartilag-e, 
with the tissues which lie m the neig-hborhood of it, these 
vessels appear to be more deeply seated in the second portion 
than in the beg-inning- of their course. At the commencement 
of the artery, to its inner side, it has the Trachea : passing- 
above, the Thyroid g-land, passing- above that, the cartilag-es 
of the larynx; and then, still hig-her up, the side of the 
pharynx. 

As the Pneumog-astric nerve passes downward, it g-ives off 
an important branch, w^hich lies over the subclavian artery, the 
Recurrent Laryng-eal. This branch winds upwards behind 
the subclavian artery, first passes obliquely inward, and then 
passes behind the common carotid artery, and runs into 
the muscles along- the side of the neck. As the nerve runs 
upward, it bears a three fold relation to the common carotid 
artery : first behind and external, then behind and then to the 
inner side. A branch of the subclavian, the inferior thvroid 
is also a posterior relation of the first portion. 

Unlike nearly all arteries, the common carotid gfives off no 
branches in its course. The usual arrang-ement is that the 
arteries give off branches to those structures among which 
they lie. The branches of one of its terminal branches supply 
the upper region of its course, while the branches of the sub- 
clavian supply the lower region. 

External Carotid. 

The external carotid artery, one of the two terminal branches 
of the common carotid, begins where that artery bifurcates 
about on a level with the upper border of the thyroid cartilage 
and, continuing the direction of the common carotid, passes 



THE VASCULAR SYSTEM. 291 

beneath the posterior belly of the dig-astric and the stylo-hyold 
muscles, enters the substance of the parotid g-land and termi- 
nates in that g-land behind the neck of the condyle of the lower 
jaw by dividingf into two branches, the temporal and the 
internal maxillary arteries. The temporal continues the 
course of the external carotid to mount over the zyg"oma and 
be distributed to the side of the head by two branches, while 
the internal maxillary passes inward, behind the neck of the 
condyle of the lower jaw to supply the deep structures of the 
face. 

This artery is divided, for convenience of description into 
three portions. 

Relations. — The first portion of the external carotid lies in 
the superior carotid triang-le, its length varying- as the common 
carotid divides on a level with, above or below the upper 
border of the thyroid cartilag-e, for it extends from the bi- 
furcation of the common carotid to the stylo-hyoid and pos- 
terior belly of the digastric. It is covered by the integument 
and platysma and deep cervical fascia, is slightly overlapped 
by the sterno-mastoid and is crossed in front by the hypo- 
glossal or twelfth nerve, near the termination of this portion, 
and the lingual vein near its beginning. At its commence- 
ment 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. 

The second portion is that which is crossed by the stylo- 
hyoid and posterior belly of the digastric. Its coverings are 
integument, platysma, stylo-hyoid and posterior belly of the 
digastric. The stylo-glossus and pharyngeus muscles, glosso- 
pharyngeal and superior laryngeal nerves cross between this 
and the internal -carotid about on a line between the second 
and third portions. 

The third ■a^\(S. last portion extends from the stylo-hyoid and 
posterior belly of the digastric to the termination of the artery 
behind the neck of the condyle of the lower jaw. It lies embed- 
ded in the substance of the parotid gland and is crossed, super- 
ficially, near its termination, by the facial nerve and the facial 



292 DESCRIPTIVE ANATOMY. 

and temporo-maxillary veins. The first portion is most 
superficial, the second the shortest and the third the long-est 
and deepest. 

Branches. 

Superior Thyroid Occipital" 

Lingual Posterior Auricular 

Facial Ascending- Pharyng"eal 

Parotid ean. 

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 g-ives off six sing-le bran- 
ches, and a set to the parotid gland. The first three arise 
from the anterior 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 the upper part of the thyroid gland to which it is dis- 
tributed. It gives off the following branches: 

1st. hyoid, which passes forward just beneath the hyoid bone 
to be distributed to muscles and anastomose with its fellow of 
the opposite side. 

2nd. superior laryng-eal, which passes forward on the thyro- 
hyoidean membrane and pierces it to be distributed to the 
mucous membrane of the larynx, anastomosing with Its fellow. 

3rd. crico-thyroid, which passes across the crico-thyroid 
membrane and gives branches which pierce it to reach the 
mucous membrane of the larynx anastomosing with its fellow. 

4th. muscular or superficial descending braiich ^hxch. passes 
downward and outward across the common carotid to supply 
the sterno-mastoid. 



THE VASCULAR SYSTEM. 293 

II. Lingual. 

The lingual arter}^ is divided into four portions: 1st, it 
descends obliquely inward, over the extremity of the hyoid 
bone covered only by the skin and platysma; 2d, it passes for- 
ward along- and above the hyoid bone, is crossed by the digas- 
tric and then covered by the hyo-glossus muscle; 3d, it ascends 
to the under aspect of the tongue; 4th, in riins 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: 

1st. Hyoid, which runs inward along the upper border of 
the hyoid bone to be distributed to muscles and anastomose 
with its fellow. 

2d. dorsalis lingiicc, which ascends to the dorsum of the 
tongue along the posterior border of the hyoglossus muscle to 
supph^ the back of the tongue muscous membrane and soft 
palate. 

3d. subling-iial, 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 mu- 
cous 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 forward 
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 superficial, being 
covered only by the skin and platysma; but it soon enters the 
submaxillary gland and is crossed by the stylo-hyoid and pos- 
terior belly of the digastric. When it leaves the gland and 
mounts over the jaw it isagain superficial, being covered only by 



294 DESCRIPTIVE ANATOMY. 

the integ'ument 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 
divided into those g-iven off below the jaw, five in number, 
and those on the face, also five in number. v 

1st. inferior -palatine, which ascends to the soft palate, 
tonsils, E)ustacian tube, stylo-pharyng-eus and stylo-g-lossus 
muscles. 

2d. tonsillar, which ascends to the tonsils. 

3d. submaxillary , which are from three to five in number 
and ascend to the submaxillary g-land. 

4th. submental, which runs forward beneath the lower jaw 
and passing- over the symphysis menti terminates by inoscu- 
lating- w^ith the inferior labial. It lies on the mylo-hyoid 
supplies neig-hboring- muscles and anastamoses with the sub- 
maxillary before running- over the chin. 

5th. 77iuscular branches distributed to neig-hboring- branches. 

The five branches from the second portion are as follows : 

1st. inuscular or buccal, which are branches to adjacent 
muscles. 

2d. inferior labail, which runs forward beneath the skin of 
the lower lip, supplies muscles in its course and anastamoses 
with the submental inferior coronary and the inferior dental. 

3rd. inferior coronary, which skirts the edg-e of the lower 
lip, anastanlose with its fellow of the opposite side, with the 
mental branch of the inferior dental and with the inferior 
labial and supplies muscles and g-lands in its course. 

4th. superior coronary, which skirts the edg-e of the upper 
Hp, giving- off a branch to the septum of the nose, arteria septi. 
This artery anastamoses with its fellow and supplies struct- 
ures in its course. The arteria septi passes upward to ramify 
on the septum of the nose. 

5th. 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 



THE VASCULAR SYSTEM. 295 

up along- side of the nose, it g-ives off small branches to the 
cheek and terminates by anistaraosing- with the nasal branch 
of the opthalmic. 

The inferior labial and inferior coronary very frequently 
comes off by a common trunk. Sometimes it is a common 
trunk which divides into the inferior and superior coronary 
arteries. 

IV. Occipital. 

The occifiital branch of the external carotid passes upward 
and backward to the occipital g-roove of the temporal bone, 
beneath the muscles attached to the mastoid process, thence 
mounting- on the posterior aspect of the occipital bone and 
piercing- the fascia which connects the cranial attachment of 
the trapezius with the sterno-cleido-mastoid becomes superfi- 
cial and is distributed to the back of the head. The hypog-lossal 
nerve winds around, from behind forward — it crosses over the 
internal carotid artery, the internal jugular vein, the pneumo- 
gastric and spiral accessory nerves. Its branches are : 

1st. Sterno-mastoid, which, sometimes arising- directly from 
the external carotid, descends to the sterno-mastoid muscle. 

2nd. muscular branches to stylo-hyoid and dig-astric. 

3rd. two small branches auricular to the concha and menin- 
geal to the membranes of the brain. 

4th. f>rinceps 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 
transversus calli; and a deep branch which passes beneath 
the complexus to anastomose with the profunda cervicis. 

V. Posterior Auricular. 

The -posterior auricular ya.'^'^^':^ upward and backward behind 
the ear and is distributed by an aiitcrior 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-mastoid 
foramen to be distributed to the ear; the auricular which is 
distributed to the back part of the cartilag-e of the ear — the 
mastoid which passing- over the sterno-mastoid is distributed 
to the scalp behind and above the ear. 



2% DESCRIPTIVE ANATOMY. 

VI Parotidean Branches. 

T)iQ parotidean branches, four or five in number, are distri- 
buted in the parotid g"land as the external carotid is passing- 
through it. 

Ascending Pharyngeal. 

The ascending- -pJiaryngeal branch spring's from the externa^ 
carotid just at its origin and passes up beside the pharynx to 
the base of the skull, where it divides into a mening-eal branch 
to enter the cavity of the cranium throug-h the jugular foramen, 
and a pharyngeal branch to adjacent parts. 

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 tempo- 
ral. 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 fellov/ 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 
terminates. 

1st. transverse facial which arises below the zygoma, and 
passes transversel}" forward on the masseter muscle parallel 
with Steno's duct. It anastomoses with the facial. 

2nd. anterior auricular, to the front of the auricle. 

3rd. orbital, which runs forward to the outer angle of the 
eye. 

4th. jniddle temporal, which plunges into the substance 
of the temporal muscle where it is distributed. Its name is 
derived from its situation between the two surperficial tempo- 
ral arteries and the deep which spring from another trunk. 



THE VASCULAR SYSTEM. 297 

The Internal Maxillary. 

The internal maxillary is the larg-er of the two terminal 
branches of the external carotid. The course of the artery is 
divisible into three portions. T\\t first portio}i passes inward, 
forward and upward behind the ramus of the inferior maxilla, 
between it and the internal lateral lig-ament. The second 
portion passes forward and upward between the internal 
pteryg-oid muscle within and the temporal and masseter mus- 
cles without. The third portion disappears into the spheno- 
maxillary fossa. Its branches are sixteen in number, as 

follows : 

First Portion— Four Branches. 

1st. tympanic which enters the tympanum throug-h the 
fissure of Glaser. 

2nd. meniniy-ea media, which ascends to enter the cavity of 
the cranium throug-h 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 rammify over the 
dura. The posterior branch passes over the squamous por- 
tion of the temporal and divides into branches on the occipital. 
These branches anastamose with each other and with the ante- 
rior and posterior meningeal. They supply the dura and the 
bone. 

3rd. The mcning-ea parva, which enters the cavity of the 
cranium through the foramen ovale. 

4th. inferior dental, which descends to enter the dental fora- 
men of the inferior maxilla and runs forward in the bone 
giving- a branch to each fang of every tooth in the lower jaw. 
Just before entering the dental foramen it gives off a branch 
called mylo-hyoidean ; and when it reaches the mental fora- 
men 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. 



298 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 anastamose 
with the superficial temporal arteries and supply the temporal 
muscle. The ^/erv^o/rt' branches, as the name indicates, su'^- 
ply the pteryg"oid muscles. The masseteric branch runs 
through the sig^moid notch and supplies the masseter from its 
deep surface. The buccal passes forward between the internal 
pterygoid and the lower jaw and supplies the buccinator. It 
anastamoses with the facial. 

Third Portion. 

1st. sttjyerior dental, 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. 

2nd. 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. 

3d. descending palatine, which descends along the posterior 
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 pala- 
tine foramen. 

4th. spheno- palatine, which enters the nose through the 
spheno-palatine foramen and divides into two branches, one be- 
ing distributed to the septum and the other to the mucous 
membrane of the outer wall and antrum maxillare. 

5th. ptergo-palatine, which runs backward in the pterygo- 
palatine canal to the pharynx, E^ustachian tube and neighboring 
parts. 

6th. Vidian, which passes backward along the pterygoid 
canal and, like the preceding, is distributed to the mucous 
membrane of the pharynx and E)ustachian tube. 



THE VASCULAR SYSTEM. 299 

The Right Subclavian. 

The Rig-ht Subclavian artery is one of the two terminal 
branches of the arteria innominata, the other being- the rig-ht 
common carotid. It commences upon the upper border of the 
rig-ht sterno-clavicular articulation, arches upward and out- 
ward, passing- between the Scaleni muscles; then turns down- 
ward and outward, and terminates by becoming- the axillary 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 hig-hest part of the arch 
being- that which passes behind the Scaleni muscles. 

This warrants the sub-division of the artery into three 
f>ortions. 

The -first commences by a bifurcation of the arteria innom- 
inata and terminates at the inner border of the scalenus anti- 
cus; 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 sub- 
divided 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 covering-s of this artery are the skin, su- 
perficial fascia, platysmamyoides muscle, one layer of the deep 
cervical fascia, the sterno-cleido-mastoid muscle, with the sec- 
ond layer of deep cervical fascia, and the posterior belly of the 
omo-hyoid muscle. It is better to take the relations of the ar- 
tery 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 
pneumog-astric nerve, with its recurrent laryng-eal branch, ex- 
ternal to that the internal jug-ular vein, then the phrenic nerve, 
then the scalenus anticus muscle, then the suprascapular 
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 



300 DESCRIPTIVE ANATOMY. 

vein, the recurrent laryngeal nerve, the lung" and pleura, and 
the first rib. Behind, the recurrent laryngeal, the cervical 
portion of the sympathetic nerve, the vertebrae, the Scalenus 
anticus 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: 

First Portion. The first ^orfio)i 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 pneumogastric nerve, giving off here its recurrent laryn- 
geal branch ; external to this, the internal jugular vein ; and 
external to this, usually, the phrenic nerve. The course of the 
phrenic is downward 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 off 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 in- 
ner side at its commencement is the right common carotid. Be- 
hind it is the recurrent laryngeal, and the cervical portion of 
the sympathetic, the cardiac branches of which cross its 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. The second portion forms the top of 
the bow; and runs transversely outward. It runs behind the 
Scalenus anticus muscle; and is co-extensive with its breadth. 



THE VASCULAR SYSTEM. 301 

In front are the inteofument superficial fascia, the platysma 
first layer of deep cervical fascia, the sterno-cleido-mistoid 
second layer of deep cervical fascia, with branches of the cer- 
vical plexus extending- over the clavicle. Occasionally on its 
front is the phrenic nerve. The suprascapular artery and the 
transversa colli branches of the subclavian pass across the front 
of the scalenus anticus muscle; and should be considered 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 lung-s. 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. The third portion is the downward 
and outward part, extending- from the outer edge of the Scale- 
nus 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 platysma ; and to a slig-ht extent, in 
many cases, by the outer edg-e of the sterno-cleido-mastoid ; 
and, in a few cases, where this muscle has a redundant orig-in, 
the third portion of the artery is covered completel}^ by it. 
The artery lies in the triangular space bounded above b}^ 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. Crosssing- in front of it are the supra- 
scapular artery, a branch of the subclavian itself, which passes 
outward just beneath the upper border of the clavicle. This 
artery is accompanied by its own vein. Crossing- the front of it 
from above is the external jug-ular vein, which descends the 
neck lying- just behind the outer edg-e of the sterno-cleido- 
mastoid muscle ; and, after having received on the front of 
the artery the suprascapular and tran verse veins, it terminates 
in the subclavian on the outer side of the scalenus anticus. 

The subclavius muscle, the descending- branches of the cer- 
vical plexus, and the nerve to the sub-clavius muscle are also 
in front. Owing- to the curve in the course of the artery, 
what has heretofore been called its upper aspect now becomes 



302 DESCRIPTIVE ANATOMY. 

its external. The brachial plexus of nerves has been described 
as being an external 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 ter- 
mination. The vein, it will be observed, is a relation of the 
iirst 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 ter- 
mination, 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 lig-ation of 
this vessel is preferably performed in the third portion of its 

course. 

Branches. 

Vertebral 
( Inferior Thyroid Internal Mammary 
Thyroid Axis < Suprascapular Superior Intercostal 

( Transversa Colli Profunda Cervicis. 

These seven branches usually rise by four trunks: the ver- 
tebral, thyroid axis, internal mamary, and the common trunk 
for the superior intercostal and cervicalis profunda. 

Vertebral. 

The vertebral is the first and largest branch of the subclav- 
ian. 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 
artery never enters it. It passes upward through the fora- 
mina of the transverse process, winds backward around the 
superior articular process of the atlas, enters the cavity of the 
cranium through the foramen magnum, and at the lower bor- 



THE VASCULAR SYSTEM. 303 

der of the pons Varolii unites with its fellow of the opposite 
side to form a sinsfle trunk, called the Basilar artery, which 
runs upward and forward to the anterior border of the pons, 
where it divides into four terminal branches, two on either 
side. At its orig-in the internal jugular vein and the infe- 
rior thyroid artery lie in front of it. On the left side, while 
l\4no- between the scalenus anticus and longus coli muscles, 
the thoracic duct passes in front of it. Besides its terminal 
branches it g-ives off the following- branches : 

1st. lateral spinal, which are g^iveu off as the artery ascends 
the neck to enter the intervertebral foramina. They there 
divide into two branches: one for the bodies of the vertebrae, 
and the other for the spinal cord and its membranes. That for 
the spinal cord reaches its 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. 

2nd. The muscular branches are unimportant. They come 
from the lower portion of the artery, and are distributed to 
the cervical muscles. 

3d. Tho. posterior meningrcal are small branches distributed 
to the dura mater of the cranium. 

4th. The anterior spinal zx\'$,q's, 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 
anterior aspect of the cord. 

5th. 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 the lateral spinal. This also forms a branch 
passing- down the spinal cord. 

<)th. ^\\Q. posterior inferior ce7'ebellar 7vc\v,^'s> just before the 
termination of the vertebral; and passing- across the lateral as- 
pect of the medulla, winds around the inferior portion of the 
cerebellum, to which it is distributed. 



304 DESCRIPTIVE ANATOMY. 

Basilar. 

The Basilar ?ivX.Qry 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: 

1st. transverse, which are numerous small branches given 
off to each side of the pons Varolii. 

2nd. 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. 

In addition to these way-side branches, the basilar artery 
gives off the following terminal: 

1st. 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. 

2nd. T\\Qj^osterior cerebral also winds around the outer bor- 
der 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 two vessels are formed by the bifurcations of the bas- 
ilar artery, which just before it divides, gives off numerous 
small branches, which enter the minute foramina constituting 
the locus ^erforatus at the base of the brain. 

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. 



THE VASCULxVR SYSTEM. • 305 

Inferior Thyroid. 

The inferior thyroid, the branch from which the plexus re- 
ceives its name, first passes vertically upward for a distance of 
an inch and one-half or two inches. It then turns inward, cross- 
es behind the sheath of the common carotid artery to reach 
the thyroid gland. It gives off branches, or twigs, called 
lary)i§eal, tracheal, and ocsopliag-cal, which are distributed to 
the structures named: the larynx, the trachea and the oesopha- 
gus. 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 
processes to be distributed to muscles and glands in the 
neck. 

Suprascapular. 

The suprascapular, 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 outwafd over the scapula, crossing in its course the 
third portion of the sudclavian. It passes over the transverse 
ligament of the scapula to reach its dorsum in the supraspinous 
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 infraspinous fossa, to 
communicate with vessels in that situation, chiefly the dorsalis 
scapula? branch of the axillary. 

Transversa Colli. 

Next to the inferior thyroid, the transversa colli is the larg- 
est of the branches of the thyroid axis, and the least frequent 
of its progeny. It passes across the side of the neck over the 
scalenus anticus muscle, above the level of the second portion 
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 superjicialis and tlie posterior scapular. The cer- 

Des Anat— 20 



306 DESCRIPTIVE ANATOMY. 

vicalis sti-perficialis runs upward to anastomose with the 
superficial branch of the arteria princeps cervicis from the oc- 
cipital. The -posterior sca-piilar, much larger than the preced- 
ing-, passes to the vertebral border of the scapula; and des- 
cending along it, anastomoses with the dorsalis scapula 
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 su-perior epigastric and 
mtisculo-phrenic. It is accompanied by satellite veins, lying 
upon either side. At its origin it is covered by the internal 
jugular and sub-clavian veins, and has crossing it the phrenic 
nerve. Its branches are : 

1st. The comes nervi -phrenici, which arises at the upper 
portion of the vessel. It is a long and slender branch ; and 
accompanies the phrenic nerve, having the same relations as 
that nerve, and terminates by anastomosing w^ith the other 
arteries of the diaphragm. 

2nd. The anterior intercostal, which are given off to the 
intercostal spaces, over which the internal mammary passes. 
Kach passing outward, soon divides into two branches, one 
for the upper and the other for the lower border of the edges 
of the ribs. These branches occasionally spring separately 
from the artery. They first lie between the intercostal mus- 
cles and the pleura ; and then between the two intercostal 
muscles. 

3rd. perforating- branches. These are usually six in num- 
ber, corresponding 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. 

4th. The mediastinal, small and unimportant branches, 
which supply the structures of the anterior mediastinum. 



THE VASCULAR SYSTEM. 307 

5th. Pericardiac bra)iches, 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 larg-er, the superior epig-astric, leaves 
the thoracic cavit}" 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 
anastomosis in the body, establishes a connection between the 
arteries in the upper and the arieries 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 miisculo-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 inter- 
nal mammary itself, and performing the same service, and in 
addition giving off a branch to the diaphragm. 

Superior Intercostal. 

The superior intercostal and profundus cervicis usually 
spring by a common trunk from the second portion of the 
subclavian artery, though occasionally they rise from the third 
portion, and occasionally by separate trunks. The superior 
intercostal curves backward from the apex of the pleura until 
it reaches the head of the first rib, when it changes its direc- 
tion, and supplies the first intercostal space after the manner 
of all intercostal arteries. 

Profundus Cervicis. 

The profundus 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 
vertebra, 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 sub-division of the artery of the 



308 DESCRIPTIVE ANATOMY. 

Upper extremity. It beg-ins 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 pecto- 
ralis major, and through part of its extent by the pectoralis 
minor, and of course by the skin, superficial and deep fascias. 
Throughout its course its vein lies to its inner front aspect. 
The brachial plexus of nerves is a continuous relation, lying 
to its outer side in the beginning, on all three sides in the sec- 
ond portion of its course, while the terminal branches bear 
various relations to the third portion of the artery. The rela- 
tionship to the pectoralis minor warrants the subdivision of 
the vessel into three portions, each of which should be studied 
in detail. ^\lq, first -portion extends from the beginning of the 
vessel to the upper border of the Pectoralis minor muscle; and 
is contained in the triangular space bounded above by the 
clavicle, below by the pectoralis minor, and externally by the 
humerus. The second -portion commences at the upper bor- 
der of the pectoralis minor, and terminates at its lower border 
by becoming the third portion. The third portion, commenc- 
ing at the lower border of the pectoralis minor, terminates at 
the lower border of the tendons of the latissimus dorsi and 
teres major by becoming the brachial artery. 

First Portion. 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 tendon of the subscapularis. Its vein 
is internal and in front ; while the brachial plexus of nerves 



THE VASCULAR SYSTEM. 309 

lies to its outer side and slio-htly above it. More superficially, 
in the interval between the pectoralis major and the deltoid, it 
is crossed by the cephalic vein. Behind it is the respiratory 
nerve of Bell. 

Second Portion. 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 corresponds to the position of the third serration 
of the serratus mag-nus. Behind, it rests upon the subscapu- 
laris. The cords of the brachial plexus are here divided into 
three : internal, external, and posterior, which bear the corres- 
ponding- relations to the second portion of the axillary, while 
the vein is still internal and anterior. 

Third Portion. The third portion is covered by the pecto- 
ralis 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 exter- 
nal to it is the coraco-brachialis and the short head of the biceps. 
At the beg-inning- of this portion the brachial plexus breaks up 
into its terminal branches; and all of these branches bear some 
relation to the vessel. On the front of its commencement the 
external and internal cords each g"ive off a branch, which unite 
to form the median nerve. This nerve immediately drops to 
the outer side of the vessel; and maintains that relation to its 
termination. The outer cord also g-ives off the musculo-cutane- 
ous, which is an external relation for a short distance, then, 
plung-ing- into the fibres of the coraco-brachialis, ceases to be a 
relation of the axillary. The inner cord, after contributing- 
one root to the median, g-ives off the ulna and internal cutaneous 
nerves, both of which are fixed internal relations. To the in- 
ner front aspect is the vein. Behind, it rests upon the circum- 
flex nerve and the subscapular artery for a short distance, while 
the last cord of the plexus, the musculo-spiral, is a continuous 
posterior relation. 

The Branches. 
Short Thoracic Long- Thoracic 

Acromial Thoracic Subscapular 

Thoracica Alaria Posterior Circumflex 

Anterior Circumflex 



310 DESCRIPTIVE ANATOMY. 

The point of orig-in of the brcDiches of the axillary is very 
uncertain, and no perfectly accurate description applying- to all 
cases can be written. Usually the short thoracic and the acro- 
mial 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. Sometimes 
they will rise by common branches ; and almost any arrang-e- 
ment may be anticipated in the orig-in of the branches of 
this vessel. 

Short. Thoracic. 

The 5/zorz' //^or«c:^'<; usually arises by a common trunk with 
the acromial thoracic. It passes inward along- the upper bor- 
der of the pectoralis minor, then between the two pectoral 
muscles to be distributed to the upper intercostal muscles and 
a part of the serratus mag-nus, anastomosing- with the inter- 
costal arteries. It frequently sends branches to the pectoral 
muscles, and occasionally to the mammary g-land. 

Acromial Throacic. 

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" 
thoracic. 

1st. The ^^dT^ora/ passes between the pectoralis major and 
minor, and is distributed, in the main, to the mammary g-land, 
some branches g'oing to the pectoral muscles. 

2nd. The acromial, thoug-h the smallest branch, g-ives its 
name to the trunk, and passes outward across the coracoid 
process, sometimes piercing- the deltoid muscle, where it 
anastomoses with the circumflex and suprascapular arteries, 
forming- the plexus around the acromion process. 

3d. 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. 

The thoracica alaria are not infrequently branches from the 



THE VASCULAR SYSTEM. 311 

long- thoracic. They sometimss arise separately from the trunk; 
and are distributed miinly to the lymphatics, integument and 
fascia of the axilla. 

TaQlo}io thoracic arises either alone, or by a common trunk 
with the preceding-, pissing- between the pectoral muscles and 
the serratus magnus to reach the lateral aspect of the chest. 
It g-ives branches to the pectorals and to the serratus magnus, 
anastomoses with the intercostal arteries, and occasionally gives 
a large branch to the mammary gland. 

The subscapular is usually the largest branch of the axil- 
lary artery, arising generally oppDsite the lower border of 
the subscapularis. It runs downward and inward, following 
the edge of that muscle, supplies it, the teres major, the 
latissimus dorsi, anl serratus mignus, and gives branches to 
structures in the axillary space. At the inferior angle of the 
scapular it anastomoses 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 scapula: , which passing through the triangu- 
lar 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 infraspi- 
natus muscle, anastomosing with the suprascapular and the 
posterior scapular arteries. It also supplies the teres minor, 
and sometimes gives a branch to the teres major muscle. 

The anterior circumflex, a very small vessel, frequently 
arises by a common trunk with the posterior, or it may arise 
from the subscapular. It pisses 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. 

The posterior circumflex, quite a large ve^isel, arises from 
the third portion of the axillary below the subscapularis muscle, 
pisses through the quadrilateral spice bounded externally by 
the shaft of the humerus, internally by the long head of the 



312 DESCRIPTIVE ANATOMY. 

triceps, above by the teres minor, below by the teres major, 
winds around the back of the humerus, and passing beneath 
the deltoid, breaks up into a largfe number of branches, to be 
distributed to that muscle throug-hout its deep surface. In 
addition 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 an- 
terior circumflex, completing- the vascular zone around the up- 
per extremity 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 supra- 
scapular and the dorsalis scapulse, 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 beg^ins 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 
terminates half an inch, or a fing^er'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 directl}^ 
backward. 

Relations. — The muscular relations are as follows: To its 
outer side, at first, is the lower half of the coraco-brachialis 
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 ofl" by the biceps. In the first part of 
its course it lies on the internal intermuscular septum which 
separates it from the inner head of the triceps, and in the lower 
part on the brachialis anticus. 

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. 



THE VASCULAR SYSTEM. 313 

To its inner side are the basilic vein and the internal cuta- 
neous nerve. Both vein and nerve are at first beneath the in- 
vesting fascia of the arm; but as the structures pass downward, 
they both become superficial and are, consequently, internal 
to and in front of the artery. 

The median nerve lies first to the outer side of the arter}', 
then crosses it, usually in front, about the middle of the arm 
and reraai-ns a continuous internal relation. 

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 
inferior profunda artery, accompanying" the ulna nerve, bears 
also a posterior relation to the brachial. The musculo-spiral 
nerve and the superior profunda artery are momentary poste- 
rior relations above. 

Brachial at the Elbow. 

These relations are of such importance that the}^ must be 
g-iven separately. It lies on the middle of the front of the 
joint 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, externally by 
the supinator longus and above by a line drawn from one 
condyle of the humerus to the other. 

Branches. 

Superior Profunda Inferior Profunda 

Anastomotica Magna. 

The snf)cri(}r -profunda arises from the upper part of the 
brachial, and passes downward and outward. After piercing 
the intermuscular 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- 



314 DESCRIPTIVE ANATOMY. 

lar septum; and continues downward in the interval between 
the supinator long'us 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 
recurrent and also with the anastomotica mag^na, the inferior 
profunda and the posterior ulna recurrent. 

The inferior profunda ds'x'&Q-'i a little above the middle of the 
vessel, just below the superior. It immediately seeks the 
ulna nerve; and with that nerve pierces the. internal inter- 
muscular septum to pass to the inner back part of the elbow 
joint, w^here it anastomoses with the anastomotica mag-na and 
the posterior ulna recurrent. 

The anastomotica inag-)ia 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 ulna recurrent, pierces the inter-muscular septum, 
passes outward beneath the triceps, or sometimes through the 
fibres of that muscle, anastomoses with the inferior profunda 
and the posterior ulna recurrent on the inner aspect of the 
elbow joint, with the posterior branch of the superior pro- 
funda upon the outer aspect of the elbow joint, and with the 
posterior interosseous recurrent and with the anterior ulna 
recurrent. Thus the only branch forming- the vascular circle 
around the elbow joint with which the anastomotica mag"na 
does not anastomose is the radial recurrent. 

The anastomotica mag-na is thus the chief artery in completing- 
the chain around the elbow. Passing- inward it receives a 
communication from the anterior ulnar recurrent: then from 
the inferior profunda and posterior ulna 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. 

The Arteries of the Forearm. 

The arteries of the forearm are the radial and ulnar and their 
branches. 



THE VASCULAR SYSTEM. 315 

Radial Artery on the Forearm. 

The radial artery, one of the two terminal branches of the 
brachial, begins where that arterj 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 zL'rist. 

Relations. To the outer side it has throughout its course the 
supinator longus, whose belly overlaps it. With this excep- 
tion the 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. 

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 
considered a relation, while in the lower third it passes be- 
neath the tendon of the supinator longus and disappears on the 
back of the forearm. 

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. 

Ulnar Artery on the Forearm. 

The zilnar 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 inward 
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 terminates as the 
ulnar artery of the forearm by becoming the ulnar artery of 
the hand. 



316 DESCRIPTIVE ANATOMY. 

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 long-usand flexor 
sublimis dig-itorum — all the muscles of the superficial group 
except 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 anti- 
cus 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 which is also 
an external relation for about an inch. 

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 
outward 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 ulna nerves. 
Its course across the palm is known as the superficial falmar 
arch (arcus sublimis) 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 fi^nger. The ulnar nerve continues its rela- 
tion to the artery in the hand, lying to its inner side. 

Branches. 

Anterior Ulnar Recurrent Interosseous 

Posterior Tlnar Recurrent Muscular 

The anterior ulnar recurrent arises from the ulnar 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 



THE VASCULAR SYSTEM. 317 

condyle. It passes to the interval between the olecranon and 
internal condyle and communicates with the anastomotica 
mag-na and the inferior profunda. 

The interosseous is a lar^-e trunk which arises from the 
ulnar just below the elbow and quickly forks into an anterior 
and posterior interosseous. 

1st. The anterior interosseous descends on the front of the 
interosseous membrane, between the flexor profundus digito- 
rum and flexor long-us poUicis muscles, to the pronator qua- 
dratus, passing- beneath which it perforates the interosseous 
membrane and appears on the back of the forearm to inoscu- 
late with the posterior interosseous artery. It supplies the 
muscles in its route and gives off a companion branch to the 
median nerve. It communicates with the posterior carpal 
arch and the posterior interosseous. 

2nd. The posterior interosseous, as soon as it is produced, 
passes between the bones above the interosseous membrane, 
to reach the back of the forearm and descend on the back of 
the forearm, between 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 re- 
current, which ascends to the back of the elbow and commu- 
nicates with the anastomotica magna. 

The posterior interosseous artery is distributed 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 (Ulterior 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 ar- 
ticulations. 

The posterior carpal "^di^^ts backward and then runs outward 
on theback of the wrist to anastomose with the posterior carpal 
of the radial. From this arch are given off branches which 
supply the ulnar side of the back of the little finger and inter- 



318 DESCRIPTIVE ANATOMY. 

osseous branches to the next two spaces. These branches re- 
ceive the posterior and anterior perforating' arteries. 

These branches are very small and the anterior is frequently 
absent. 

Branches in the Hand. 

Communicating Dig-ital 

The communicating- branch dips between the abductor mi- 
nimi digiti and flexor brevis minimi digiti to join the termi- 
nation 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 ^«/?;^«r and dorsal collateral 
dig-ital 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 lit- 
tle 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 
primiand extensor secondiinternodiipollicis,in the order named, 
and passing through what is known as the snuff box — the 
sunken interval between the extensor ossis metacarpi pollicis 
and extensor 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 immediately dips into the palm of the hand by passing 
between the two heads of the first dorsal interosseous muscle, 



THE VASCULAR SYSTEM. 319 

and passinof across the palm of the hand from the outer to the 
inner side, terminates by anastomosing- with the communicat- 
ing:;- branch from the superficial palmar arch. The position of 
the radial in the palm is deep, lying- on the bases of the meta- 
carpal 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 tne joint, where it lies in the space between the supina- 
tor long-US and the brachialis anticus. It here inosculates with 
the anterior branch of the superior profunda. 

The muscular branches are numerous twig-s to muscles in 
the course of the artery. 

Branches at the Wrist. 

Superficialis Vols Dorsalis Pollicis 

Anterior Carpal Metacarpea 

Posterior Carpal Dorsalis Indicis 

Princeps Pollicis 

The su-perjicialis voice leaves the radial just as it turns out- 
ward and passes to the muscles of the thenar g-roup, usually 
perforating- the abductor pollicis. Sometimes it anastomoses 
with the termination of the ulna, forming- the superficial arch. 

The anterior carfal 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 ulnar and 
form the posterior carpal arch. From the posterior carpal 
arch there pass down on the dorsal interosseous muscle two 
branches called posterior interosseous besides another which 
runs along- the dorsal aspect of the ulnar border of the 
hand to supply the ulnar side of the dorsal aspect of 



320 DESCRIPTIVE ANATOMY. 

the little fing^er. The posterior interosseous pass down- 
ward to divide the one at the cleft between the little and 
ring- fingers to form dorsal collateral dig-ital branches for the 
adjacent sides of those fino-ers, 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 nietacarpea is a branch which descends on the second 
dorsal interosseous muscle to the cleft between the middle 
and index fing-ers and there divides to form dorsal collateral 
digital branches for those fingfers. 

The dor salts indicis is a small branch which passes forward 
to form the dorsal collateral digital branch for the outer side 
of the index fing-ers. 

Princeps Pollicis. 

ThQ ;p7-mceps pollicis arises just as the radial dips into the 
palm of the hand and passes forward and outward to divide and 
form collateral dig-ital arteries for the palmar aspect of the 
thumb. 

Branches of the Deep Palmar Arch. 

Radialis Indicis Anterior Interosseous 

Perforating- 

1st. The radialis indicis, coming- off close to the princeps 
pollicis, runs along- the radial border of the index fing-er to ifs 
extremity and there anastomoses with the collateral dig-ital 
artery of the superficial palmar arch. It also anastomoses 
with the princeps pollicis and g^ives a communicating- branch 
to the superficial palmar arch thus completing- the arch, thoug-h 
sometimes the superficial arch is completed by anastomosing- 
with the superficialis volae. 

The anterior interosseous are three or four small branches 
which pass forward on the front of the interosseous muscles 
to unite with the dig-ital branches of the superficial arch. 

Besides these the deep arch g-ives off two sets of unimpor- 
tant branches called perforating and recurrent. 



THE VASCULAR SYSTEM. 321 

The -perforating arteries are three in number, passing- back- 
ward between the heads of the last three dorsal interosseus 
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 bod}" of the fourth lumbar vertebra slig-htly 
to the left of the raid-line. It lies first in the thoracic, then in 
the abdominal cavity. Its direction is first upward, forward, 
and to the rig-ht; 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 Trans- 
verse Aorta, and the Descending Aorta, the latter being- sub- 
divided into the Thoracic and Abdomiiial portion of the 
descending aorta. The old sub-divisions of ascending, trans- 
verse, and descending portions of the arch have here been 
abandoned. 

The Ascending Aorta. 

The Ascending- Aorta (formerly called the Ascending- Por- 
tion of the Arch of the Aorta) begins at the base of the arterial 
ventricle, at a point behind the left edg-e of the sternum, oppo- 
site the third intercostal space, on a plane posterior to the 
pulmonary artery and anterior to the left auriculo-ventricular 
opening. It is about two inches in length, is directed upward, 
forward, and to the right, presenting- a slig-ht curve, whose 
convexity is to the rig-ht. Behind the upper border of the sec- 
ond costal cartilage of the rig-ht side it terminates by becoming- 
the transverse aorta. Just above its orig-in it is somewhat 
triangular on cross-section when distended, and presents three 
bulg-ing- prominences, which correspond to the sinuses of 
Valsalva. It lies in the fibrous pericardium, about one-fourth 
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 

Des Anat— 21 



322 DESCRIPTIVE ANATOMY. 

right, and partly to the oblique course of the pulmonary artery. 
Above the pulmonary , the aorta is separated from the sternum by 
the pericardium, some loose connective tissue, and the remains 
of the thymus g-land, should any exist. At its oriofin it is over- 
lapped in front by the rig-ht 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 descend- 
ing aorta. The top of this arch is about an inch below the 
top of the sternum ; and from it arise three large branches : 
the Arteria hinominata, the left Common Carotid and the 
Left Sub-clavian. 

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 pluras do not come in contact. It is 
crossed in the order from right to left by the left phrenic, the 
cardiac branches of the pneumogastric, and the left pneumogas- 
tric nerves. The left superior intercostal vein also crosses 
the front of the transverse aorta. Behind, it rests upon the 
trachea, behind that is the oesophagus, and in the interval be- 
tween the two the thoracic duct and the left recurrent laryn- 
geal nerve. Above, it is in relation with its three branches 
before mentioned, from right to left, and from before back- 
ward, the arteria innomiuata, left common carotid, and left sub- 
clavian ; 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 



THE VASCULAR SYSTEM. 323 

connected by means of the ductus arteriosus with the pulmo- 
nar}" artery. The portion formerly described as "the descend- 
ing" 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 2x\'&^ from the ascend- 
ing- 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 rig-ht ang-les with one another, 
which completely surround the heart. 

Branches of the Transverse Aorta. 

Arteria lunominata Left Common Carotid 

Left Subclavian 

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 C<^mmon Carotid 
at the middle of the transverse aorta; and the left Subclavian 
near the termination of the transverse aorta. 

Arteria Innominata. 

The arteria i)i)ionii}iata is the first and doubly the larg-est 
branch of the aorta. It arises from the beg-inning- of the trans- 
verse aorta, passes upward and to the rig-ht for a little less 
than two inches to terminate behind the upper border of the 
right sterno-clavicular articulation h^ dividing- into the Right 
Common Carotid and Rig-ht Subclavian arteries. In other 
words, in it are blended the rig-ht common carotid and right 
subclavian vessels. 

Relations. In front is the sternum, from which it is separa- 
ted by some loose connective tissue, by the prolong-ation of the 



324 DESCRIPTIVE ANATOMY. 

fibres of origin of the sterno-hyoid and sterno-thyroid muscles, 
and by the remains of the thymus g-land, should there be any. 
Across the front of it, just at its orig-in, passes the left innomi- 
nate vein, or g-reat transverse vein of the neck, and the right 
inferior thyroid vein. 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 pneu- 
mogastric nerve, which is a rather distant relation. 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. 
After passing above th>e left sterno-clavicular articulation, its 
relations become identical with those of the right common 
carotid, 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 ante- 
rior, the left subclavian to its left and on a plane slightly pos- 
terior. 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 thanthatat which the same vein crosses the innom- 
inate artery. It is overlapped in front by the left lung and 
pleura. Behind it, at its origin, lies the trachea, which is be- 
hind and slightly to its inner side. Crossing obliquely behind 



THE VASCULAR SYSTEM. 325 

is the left recurrent lar^^ng-eal nerve while behind and to its 
outer side is seen the thoracic duct. As it ascends, the tra- 
chea becomes an internal relation, and the oesophag-us a pos- 
tero-internal relation, the recurrent laryng-eal nerve lying- in 
the g-roove between these two structures. To its inner side 
at its commencement is the innominate artery; and above this, 
and internal and posterior 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 slig^htly posterior; while 
in the interval between the subclavian and the carotid is seen 
the pneumog^astric nerve, an antero-external relation of the 
carotid. 

The Left Subclavian. 

The left sKbclavicnid.ri^,^'^ 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 iden- 
tical with the right. 

Relations. The left subclavian is almost enveloped by the 
left pleura, which covers it in front, to the outer side, and 
behind. It has the left common carotid lying internal to it 
and slig-htly in front of it, while more superficially^ are the 
origins of the sterno-hyoid and sterno-thyroid muscles, and 
the remains of the thymus gland, should there be any. Near 
its origin, but hig-her than at the point of crossing- of the left 
common carotid, is found theg^reat transverse vein of the neck, 
while near the termination of the first portion the internal 
jug-ular and the subclavian veins of the left side unite to form 
the innominate on the front of the subclavian artery. The 
left vertebral vein is also an anterior relation. The phrenic 
nerve crosses it near the scalenus anticus muscle, and then 
passes downward, parallel to the pneumog-astric, but external 
to, and in front of, that nerve. The pneumog*astric itself lies 
in the interval between the subclavian and the left common 
carotid on a plain anterior to both, but internal to the subcla- 
vian, while external to the carotid. Below it, as well as to its 
outer side, are the pleura and the left lung". The trachea, 



326 DESCRIPTIVE ANATOMY. 

oesophagus, and recurrent lar3^ng-eal nerve migflit be considered 
distant internal relations. The relation of the thoracic duct 
should be carefully noted. It ascends nearly opposite the 
interval 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 arterv to empty into the junction of the internal jug-ular 
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 bod}^ of the fourth lumbar vertebra by dividing- into the 
two common iliacs. It consists of the Thoracic and Abdomi- 
nal Portions. 

The Thoracic Aorta. 

The thoracic -portion of the descending- aorta, commencing 
at the fourth dorsal vertebra, terminates opposite the body of 
the twelfth dorsal, slightly to the left of the mid-line, by h^- 
coming the addoniif ml ao)'ta. 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 ver- 
tebrae 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 presents a curve in its course slightly concave in 
front to correspond with the dorsal curvature of the spinal 
column upon which it rests. 

Relations . This vessel is covered throug'hout 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 bron- 
chus, lymphatics, nerves, and small blood vessels. Below this 
it lies behind the pericardium; and is completely covered over 



THE VASCULAR SYSTEM. 327 

by the left pleura and lung-. It bears an important relation to 
the (jesophag-us, thoracic duct, and pneumogfastric nerves. The 
two pneumogastric nerves course downward, one upon the 
front and the other 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 (jesophagus terminates, it is 
still further 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 azy- 
gos 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 de- 
scends. 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 vertebra?, is enveloped by the pleura, while near 
its termination the pleura covers only its outer aspect. 

Branches. 

Bronchial Intercostal 

Mediastinal Pericardiac 

(Esophageal 

The hrcuiclies of the th')racic aorta are small, although 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 ram- 
ify with the bronchial tubes. These vessels, it should be 
understood, have no connection with the pulmonary artery ; 
but simply furnish a nutrient supply for the lung tissue it- 
self. Their method of distribution belongs to the domain of 
histology. 

The (vsophafccal are a number of small twigs, four or five, 
which are successively furnished to the (esophagus as that 



328 DESCRIPTIVE ANATOMY. 

tube comes into relationship with the thoracic aorta, and which 
communicate 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 branch- 
es, are ten pairs, which rise from both sides of the thoracic 
aorta, and run out into the intercostal spaces, the upper space 
being- supplied by the superior intercostal of the subclavian, 
while the space below the last rib, or sub-costal space, is sup- 
plied by one of the terminal branches of the internal mammar3^ 
The right intercostal arteries are, of course, longer than the 
left from having to cross the vertebral column. Kach inter- 
costal 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 venaazygos major and thoracic duct. 
Further out they pass behind the sympathetic system; and lie 
first upon the external intercostal muscle, and then, at the an- 
gle of the rib, between the two intercostal muscles. They 
continue 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 
terminating each intercostal gives off a dorsal branch, whose 
distribution corresponds to the dorsal nerves; that is, it divides 
into a muscular and a spinal branch, the spinal to enter the spi- 
nal 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 
continuation of the thoracic aorta. It passes behind the dia- 
phragm, through the aortic opening, and curves backward and 
and to the left, the convexity being to the left. About the 
middle of its course it changes its direction and curves slightly 



THE VASCULAR SYSTEM. 329 

to the rig-ht, 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 indicated by a line drawn from the highest 
point of the crest of the ilium of one side to the same point of 
the opposite, or by a point selected half-an-inch below and to 
the left of the umbilicus. In addition to the curvature to the 
left, it also is sligfhtly convex forward, conforming- to the lum- 
bar portion of the spine. Owing" to the larg"e size and g^reat 
number of the branches g"iven ofiF, it is gfreatly 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 vertebra? by intervening" structures. Oppo- 
site the second lumbar vertebra is the commencement of the 
thoracic duct, the receptaculuni chyli; and throug-houtits course 
are found, passing behind it, the left lumbar veins, opposite 
the corresponding vertebras, as they mike 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 diaphragm and a portion of the S3^mpathetic, the right 
semilunar ganglion, the right vena az3'gos, and thoracic duct, 
while throughout the course of the vessel the inferior vena cava 
lies upon its right. In front is the stomach. Opposite the 
apper border of the stomach one of the largest branches of the 
abdominal aortaarises, the C(jeliac axis; and this is surrounded by 
cords of the sympathetic system, forming the solar plexus of 
nerves with its two semilunar ganglia. These ganglia are 
found lying to the front and lateral aspects of the commence- 
ment of the abdominal aorta. Below this comes the head of 
the pancreas, and immediately below this the left renal vein, 
tVe transverse portion of the duodenum, and the mesentery. 
Bilow this the aorta is covered at the front and at the sides by 
thu peritoneum and the aortic plexus of sympathetic nerves. 
Another of its branches, the superior mesenteric, lies for a 
shfjrt distance in front of it; but curves to the left to become a 
<listant relation of the arterv. Ccmvolutions of the small in- 



330 DESCRIPTIVE ANATOMY. 

testines cross ov^er the front of the vessel, and are separated 
from it by the peritoneum, which covers it throughout, the 
aorta lying- behind the peritoneum. 

Branches. 

( Phrenic ( Coeliac Axis 

Parietal -; Sacra Media Visceral - Superior Mesenteric 

( Ivumbar ( Inferior Mesenteric 

; Spermatic 
Genito-Urinary - Renal 

( Suprarenal. 

The brancJies 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 organs of digestion, and those accessory thereto ; and 
those distributed to the genito-urinary organs. 

The Parietal Branches. 

Phrenic Sacra Media Lumbar 

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 adja- 
cent arteries, most frequently the renal. Each artery runs 
backward and outward on the under surface of the diaphragm 
Below the oesophageal opening they divide 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 central tendon of the diaphragm. 
The other and larger branch passes outward on the conca\e 
under surface of the muscle, supplies the muscular fibre, ard 
inosculates with the musculo-phrenic branch of the internil 
mammary, and with the other diaphragmatic arteries. 

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 



THE VASCULAR SYSTEM. 331 

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 intercos- 
tal arteries. Passing in this way beneath the psoas ma^rnus, 
these vessels divide into an anterior branch, which corresponds 
to the intercostal artery, and a posterior branch, which corre- 
sponds to the dorsal division of the intercostal. These poster- 
ior divisions supply the small arteries of the bodies of the verte- 
bra?; and, continuing- their course, g"ive off the spinal branches 
to the contents of the spinal canal, while the remaining- portion 
is distributed to the muscles of the back. The larger anterior 
division passes forward in the broad muscles of the abdomen, 
inosculates with other vessels w^hich supply those muscles, 
mainly, for the upper branches, with the terminal branches of 
the internal mammary, and for the lower lumbars with the 
branches which spring- from the deep epigastric and ilio 
lumbar. 

The sacra nicdia is a somewhat slender branch, which arises 
just at the bifurcation of the aorta, though occasionally from 
one of its forks. It passes dow^n upon the front of the sacrum, 
gives off branches which anastomose with the lateral sacral 
arteries, 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 Coccyg-eal, Gland. 

The Visceral Branches. 

Cfjeliac Axis Superior Mesenteric Inferior Mesenteric 

The Visceral hra)iches spring from the abdominal aorta by 
three trunks, the Cieliac Axis, and the Superior and Inferior 
Mesenteric. 

The cueliac 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 di- 
rectly forward to break up into three terminal branches, the 
Gastric, the Splenic, and the Hepatic. 

Relations. The artery arises just opposite the head of the 
pancreas, upon which it rests. In front of it is the lesser 
omentum; and to the right is the lobus Spigelii, while the cords 



332 DESCRIPTIVE ANATOMY. 

of the solar plexus surround the artery in every aspect, and a 
semilunar g-ang-lion lies upon either side. Its position corres- 
ponds to the level of the upper border of the stomach, while 
immediately below it and almost in contact with it is the 
orig-in of the next branch, the superior mesenteric. On the 
left side it is relation with the cardiac end of the stomach. 

Branches. 

Gastric Splenic Hepatic 

The g-astric 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 rig-ht, runs 
along- the lesser curvature between the two layers of the les- 
ser omentum nearly to the pylorus, where it inosculates with 
the pyloric branch of the hepatic artery. Just before making- 
its turn to the rig-ht it g-ives off branches to the larg-e end of 
the stomach ; and in coursing- along- the upper border, it g-ives 
branches which pass downward to both the anterior and pos- 
terior faces of that org-an. 

The Splenic Artery. 

The ^^/e;z/6' artery is the larg-est of the branches arising- from 
the coeliac axis. It is very tortuous, runs directly from rig-ht 
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 org-an. 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 g-roove 
a little distance below the artery. 

Before reaching- the spleen, the artery g-ives off a number 
(five or six) of larg-e branches, which pass to the splenic end 
of the stomach, and, under the nime of the vasa brevia, inos- 
culate with the branches of the g-astric artery, and supply the 
cardiac or splenic end of the stomach. 

As it passes along- the upper border of the pancreas, numer- 
ous small pancreatic branches are g-iven off, which descend 
into that g-land. One of them, of larg-er size, is frequently 
individualized as the pancreatica magna. 



THE VASCULAR SYSTEM. 333 

One of its terminal branches, the g-astro-epiploica sinistra, 
leaves the artery near the spleen, runs to the right alontr the 
g-reater curvature of the stomach between the layers of the 
g-reat omentum, and about the middle of the g-reater curvature 
of the stomach inosculates w'xththQ g-astro-cpiploica dextra, an 
indirect branch of the hepatic artery. From this artery, the 
g-astro-epiploica sinistra, branches ascend to both faces of the 
stomach, and descend to supply the g-reat omentum. 

The Hepatic Artery. 

The hepatic is intermediate in size between the gastric and 
the splenic. Its usual course is to pass to the rig-ht and slig-ht- 
ly 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 
rig-ht 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 rig-ht 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: duetto 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 org-an. 

Besides these branches it produces the pyloric, which passes 
to the left along- the lesser curvature of the stomach until it 
meets the g-astric artery, inosculates with that vessel, and like 
it is distributed to both faces of the stomach. 

The next branch, g-enerally called the gastro-duodenalis, 
and described as divided into the paiicreatico-duodenalis supe- 
rior and the gastro-epiploica dextra, is preferably described as 
the g-astro-epiploica dextra. This artery, arising- from the 
hepatic, winds around the g-reater curvature of the stomach, 
g-iving- 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 pancre- 



334 DESCRIPTIVE ANATOMY. 

atico-duodenalis inferior, a branch of the superior mesenteric; 
while the parent trunk continues between the folds of the g-reat 
omentum until it inosculates with the g^astro-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, one running between the gall blad- 
der 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 
freel}^ anastomose with one another, the splenic anastomosing 
with the gastric at the left end 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 niesenteric'v^ 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 to 
reach 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 width of the pancreas, covered by that structure. It ap- 
pears in the interval between the lower border of the pancreas 
and the transverse duodenum; then crosses in front of the 
transverse duodenum; and from that point onward continues 
in the fold of the mesentery, moving with the mesentery in the 
abdominal cavity. It is accompanied throughout by the supe- 
rior mesenteric vein. 



THE VASCULAR SYSTEM. 335 

Branches. 

Vasa Intestini Tenuis Colica Dextra 

Ileo-Colic Colica Media 

Soon after its orig-in the superior mesenteric artery g-ives off 
a small branch, called the pancrcatico-duodoiaUs inferior, 
which passing- upward between thepancreasand 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 slig-htly backward; the 
concavity looks upward, to the rig-ht, and slig-htly forward. 

Vasa Intestini Tenuis. 

From the convex face arise a number of branches, varying- 
from ten to eigfhteen in number, the vasa intestini tennis. 
These branches inosculate so freely with one another that the 
circulation in the intestinal wall is still abundantly supplied 
thoug-h a larg-e number of the branches may be ligfated. 
They decrease in size from above downward ; and their 
distribution is not quite regfular, thoug'h the plan of dis- 
tribution is always the same. Thus each branch in passing- 
outward divides into an ascending- and a descending- branch. 
These branches inosculate with the corresponding- branches 
above and below so as to form a series of arches. From these 
arches are g-iven off a second set of branches, which likewise 
divide into two, and 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 num- 
ber of arches does not exceed 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 straig-ht 
vessels, the vasa recta, which pass outward on both faces 
of the small intestine, completely encircling- the g-ut and inos- 
culate with each other, so that both in its circumference and 



336 DESCRIPTIVE ANATOMY. 

in its vertical measurement the anastomoses between the ver- 
tical 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 g^eneral rule, however, the superior 
mesenteric terminates by becoming* the last of the vasa intestini 
tenuis ; and the ileo-colic is g"iven 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 larg-er 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 termina- 
tion of the superior mesenteric. The ascending- branch passes 
upward 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. 

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 anatomi- 
cal position, and divides into an ascending and a descending, 
or, more accurately, right and left branches, the descending, 
or rig-ht, branch to anastomose with the ascending branch of 



THE VASCULAR SYSTEM. 337 

colica dextra; the ascending, or left, branch to inosculate with 
the colica sinistra, which is a branch of the inferior mesen- 
teric. 

Prom the loops formed by these three vessels are supplied 
the termination of the small intestine, the csecum, or beg-iu- 
ing of the large intestine, the ascending colon, and the trans- 
verse 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 termi- 
nation, and descends obliquely to the left iliac fossa, where it 
finall}^ terminates by passing over the brim of the pelvis under 
the name of the superior hemorrhoidal artery, and becoming 
a relation of the iliac vessels. 

Branches. 

Colica Sinistra Sigmoid Superior Hemorrhoidal 

Colica Sinistra. 

The first and largest branch, the colica sinistra, passes 
downward and to the left ; and divides into an ascending and 
a descending branch. The ascending branch inosculates with 
the left branch of the colica media, and the descending w4th 
one of the sigmoid branches of the inferior mesenteric. From 
these two loops are supplied the left end of the transverse 
colon and the descending 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 
hemorrhoidal or termination of the superior mesenteric itself. 
These branches supply the sigmoid flexure of the colon. 
Des Anat— 22 



338 DESCRIPTIVE ANATOMY. 

Superior Hemorrhoidal. 

The superior hemorrhoidal d^^cenAs along- the posterior as- 
pect of the rectum, lying- between the two layers of peritoneum 
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 mesen- 
teric. 

Summary. 

From the foreg-oing- description it will be seen that the sio7n- 
ach is supplied with blood as follows: the lesser curvature by 
the loop formed between the g-astric artery and the pyloric 
branch of the hepatic; the greater curvature by the rig-ht 
g-astro-eploica f rom the hepatic and the left g-astro-eploica from 
the splenic; the splenic end of the stomach by the vasa brevia 
from the splenic artery and by branches from the g-astric. 
All of these branches communicate with one another so as to 
render the stomach a net-work of arterial branches. 

The doudenuni is chiefly supplied by the pancreatico-duod- 
enalis superior of the hepatic, which vessel is aided in its work 
by the pancreatico-duodenalis inferior from the superior 
mesenteric, establishing- a communication between the branches 
of the coeliac axis and the superior mesenteric artery. 

The small intestine from the duodenum to near the larg-e 
intestine 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 rig-ht half of the transverse colon is supplied by the loop 
betw^een the colica media and the colica dextra, the left half by 
the loop betw^een the colica media and the colica sinistra, thus 
establishing- a communication between the superior and inferior 
mesenteric arteries. 



THE VASCULAR SYSTEM. 339 

The sigmoid flexure is supplied by the sig-moid branches, 
after anastomosing- with the colica sinistra, and by the superior 
hemorrhoidal branch of the inferior mesenteric, after anasto- 
mosing* with the sig"moid branches. 

Thus, beg-inning- w^ith the first visceral branch of the abdo- 
minal aorta, we find that the three branches which supply all 
of the hollow viscera and many of the solid viscera of the abdo- 
men not only communicate with the branches g-iven 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 infe- 
rior mesenteric. 

Genito-Urinary Branches. 

Spermatic (in the male). Ovarian (in the female). 

Renal Suprarenal. 

Spermatic. 

The Sper7iialic are a pair of small branches, which arise 
from the front of the aorta, and descend behind the peritoneum 
to the brim of the pelvis, one on either side. The left sperm- 
atic arises at a lower level, and is consequently a little shorter 
than the rig-ht. Kach artery passes across the external iliac 
close to its termination, enters the deep abdominal ring-, and 
traversing- the ing-uinal canal, leaves the abdomen at the 
superficial ring- to accompany the other elements of the cord to 
the testicles, where it is distributed. In the female this artery 
is known as the ovarian. 

Ovarian Arteries. 

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 lig-ament; then reversing- its 
course, runs outward to be distributed to the ovary, a branch 
having- been g-iven to the uterus, to the laminai of the broad 
lig-ament, and to the Fallopian tube. Other branches continue 
along the round lig-ament, throug-h the in^^uinal canal, to the 
integ-ument of the labia and g"roin. 



340 DESCRIPTIVE ANATOMY. 

Suprarenal. 

The suprarenal ?iVQ a pair of small arteries, which arise from 
the aorta above the orig-in of the renal, and pass outward on 
either side to be distributed to the suprarenal capsule. These 
arteries frequently arise from the renal artery itself ; and g"eu- 
erally there are two or three on either side of the body. 

Renal. 

The renal arteries are a pair of larg-e 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 of them and the ureter behind 
them. On the rignt side the renal artery passes behind the 
vena cava. Just as they reach the hilum of the kidney they 
break up into, usually, three branches, one of which frequently 
goes in front of the renal vein. They enter the hilum of the 
kidney to be distributed 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. 

^heco7n}Jion, or -primitive, iliac artery oiQ2.<z\\ side begins by 
being one of the terminal branches of the abdominal aorta, where 
that vessel terminates a little to the left of the body of the 
fourth lumbar vertebra, the exact point of division, however, 
varying slightly, sometimes as much as an inch. From this ori- 
gin the artery passes downward and outward to the brim of 
the pelvis to terminate on the side of the disk between the fifth 
lumbar vertebra and the sacrum by dividing 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 mid- 
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 termi- 



THE VASCULAR SYSTEM. 341 

nation by the right ureter, thoug-h this sometimes extends to 
the external iliac. Convolutions of the small intestine and 
sympathetic 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 mag-nus muscle. Behind it is the left common iliac 
vein, which joins the rig-ht 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 directly behind it. 
It lies on the last lumbar vertebra. 

Left Common Iliac. 

Relations. The Left common iliac i?, crossed in front by the 
sigmoid flexure of the colon, by the superior hemorrhoidal 
artery, and, near its termination, usually, b}^ the left ureter. 
External 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 it- 
self 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. Its course aud 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 pro- 
cess of the ilium and the symphysis pubis. 

Relations. To the outer side of the artery is the psoas mag- 
nus muscle, separated from it by the iliac fascia, which throws 
a covering over the artery and vein. In front is the peritoneum, 



342 DESCRIPTIVE ANATOMY. 

the sub-peritoneal fascia, and convolutions of the small intestine . 
The vermiform appendix usually lies on the front of the artery, 
separated from it by the peritoneum. Near its termination the 
artery is crossed in front by the g-enital branch of the g"enito- 
crural nerve, and at the middle by the spermatic artery. In 
the female of course there is no spermatic artery to cross. 
Sometimes it is crossed at its beginning- by the ureter, thoug-h 
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 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 liga- 
ment 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 internal and on a 
plane posterior, and then directly behind. 

Branches. 

Deep epigastric Deep Circumflex Iliac 

The deep e-pigastric 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 com- 
munication between the arteries of the upper and the arte- 
ries 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 obturator artery. In addition 
to the communicating branch to the obturator, it gives off a 



THE VASCULAR SYSTEM. 343 

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 deep circumflex iliac, the second branch of the exter- 
nal iliac, arises from the outer side of the external iliac just 
above Poupart's ligament, and a little higher up than the 
epigastric. It lies beneath the peritoneum ; passes upward 
and outward 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-lumbar, gluteal and intercostal arteries, the 
other continues along the crest of the ilium to anastomose 
with the lowest lumbar artery. In its course it gives off mus- 
cular branches, which aid in supplying the broad muscles of 
the abdomen, and cutaneous branches, which pierce to the 
skin and anastomose with other cutaneons branches. 

The Femoral Artery. 

The/emoral 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 issuperficial, lying in Scarpa's triangle, having the sarto- 
rius to its outer side and the adductor longus to its inner side. 



344 DESCRIPTIVE ANATOMY. 

It enters the triano-le about the middle of the base and passing- 
tHrough the centre leaves it usually about at its apex by passing- 
beneath the sartorius. It then descends, lying- on the front of 
the insertion of the adductor long-us, 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 long-us and adductor 
magnus throw over the artery to the vastus internus; so that 
the last inch or two of the femoral artery is the deepest portion 
being covered by the skin, superficial fascia, fascia lata, sarto- 
rius 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 Sep- 
arated from the artery by the tendinous arch. 

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 outvv^ard, 
so as to get first behind and than external. In the upper por- 
tion of its course the artery has from one-fourth to one-half an 
inch from 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 crural 
branch of the genito-crural nerve crosses the artery in front 
in its upper part. 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 
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 to 
the pectineus, when that musgle 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. 



THE VASCULAR SYSTEM. 345 

sometimes not more than half an inch, while occasionally more 
than two inches, there arises a larg-e trunk, known as the Deep 
Femoral or Profunda Femoris. At its orig-in this vessel is 
external to the femoral; but quickly chang-es its direction to 
pass downward and inward and become a posterior relation, 
which position it maintains until the two vessels are separated 
b}' the adductor longfus 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 
arter3% femoral vein, profunda artery, profunda vein. 

Branches. 

Superficial Epigastric Deep External Pudic 

Superficial Circumflex Iliac Profunda Femoris 

Superfi.cial External Pudic Anastomotica Magna 

Muscular 

Soon after its commencement the femoral artery gives oif 
four small branches ; the Superficial Epigastric, the Super- 
ficial Circumflex Iliac, the Superficial External Pudic, and 
the Deep External Pudic. These are all cutaneous. 

The superficial cpig-astric frequently arises by a common 
trunk with the superficial circumflex iliac. It first passes 
upward 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 of 
the abdominal wall ; and anastomoses with the cutaneous 
branches of the deep epigastric. 

The superficial circiunfiex iliac, arising either in common 
with the superficial epigastric, or separately from the femoral, 
pisses upward and outward, parallel with Poupirt's ligament, 
toward the crest of the ilium. It supplies the superficial 
inguinal glands, the skin from the upper front portion of the 
thigh ; and inosculates with the superficial branches of the 
deep circnmflex iliac. 



346 DESCRIPTIVE ANATOMY. 

The superficial external ■pitdic arises from the inner aspect 
of the femoral, and passes in front of the femoral vein toward 
the g-enital organs. This artery either passes through the 
fascia lata or through the cribriform fascia covering the saphe-^ 
nous 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 sacrotum 
in the male and the labia in the female. 

The deep external pudic sometimes arises in common with 
the superficial external pudic, runs inward behind the femoral, 
then passes across the pectineus muscle and perforates the 
fascia lata close to the syoiphysis pubis. It inosculates with 
branches of the superficial perineal artery, and supplies the 
sacrotum 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 sometimes, 
more, the femoral artery gives off from its outer posterior 
aspect a branch called the profiinda femoris which is almost 
as large as the continuation of the femoral itself. The direction 
of the profunda is for a short distance downward and outward, 
then curving inward, almost immediately after its origin, it 
descends vertically 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 raagnus, 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 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 structures 
lie in the following order from before backward: femoral artery,, 
femoral vein, profunda vein, profunda artery. 



THE VASCULAR SYSTEM. 347 

Branches of the Profunda. 

External Circumflex Internal Circumflex 

Three Perforating- 

The extcDial circumflex arises early from the profunda and 
passes outward around the upper extremity of the femur, g-iv- 
ing* off two sets of branches, one ascending* to the g-luteal region 
and the other descending- to the outer aspect of the thig-h and 
knee-joint. These branches supply the muscles on the outer 
front aspect of the thigh, anastomosing- above with the g-luteal, 
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 perfo- 
rating- and obturator. In addition to supplying the muscles on 
the inner aspect of the thig-h, this vessel g-ives a branch to the 
hip-joint. 

The three perforating arteries. As the profunda femoris is 
descending- it g-ives 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 thig-h and supply the posterior femoral 
muscles. 

Anastomotica Magna. 

The anastomotica mag'na, 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- saph- 
enous 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 
branches of the popliteal and with the recurrent branch of the 
anterior tibial. 



348 DESCRIPTIVE ANATOMY. 

Besides the six foreg-oing- branches the femoral artery g-ives 
off muscular branches to the muscles in its course. 

The Popliteal Artery. 

The. poftliteal artery ho.gm's, 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 thigfh througfh the opening- 
in the adductor mag-nus muscle. Its course is downward and 
outward (the obliquity being- g-reatest at first) throug-h the 
popliteal space to the lower border of the popliteus muscle, in 
front of the tendinous arch of the soleus — a point which corre- 
sponds 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-stringf 
muscles, and hence enters below the upper ang-le of the space 
and on its inner wall. The biceps is to its outer side and 
diverg-es from the artery as the latter descends. The heads of 
the g-astrocnemius are distant external and internal relations 
in the middle of the vessel, but become closer and superficial 
relations towards its termination owing- to their converg-ence. 
The artery rests first on the lower third of the femur, then 
on the posterior lig-ament of the knee-joint and then on the 
fascia covering- the popliteus muscle. 

Relations to Cords. In the popliteal space are found the 
popliteal artery and vein and the internal popliteal nerve. The 
artery and vein enter the space tog-ether, on its inner side below 
the superior ang-le, with the vein behind and external to the 
artery and closely adherent to it. As the structures descend, 
the vein winds around the artery and, while remaining- behind, 
becomes also internal. The nerve enters the space at its apex 
and is, consequentl}^ external to the artery and vein as well 
as behind. As the artery is inclined outward and the nerve 
inward this relation chang-es so that the nerve becomes 
internal and behind. From behind forward, throug-hout the 



THE VASCULAR SYSTEM. 349 

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 hug-g-ing- the artery; in the middle third the 
vein and nerve are directly behind; in the lower third the vein 
and nerve are behind and internal. The g-reat sciatic nerve 
rarely divides at the apex of the popliteal space, so that it 
is more correct to say that the g-reat sciatic is the posteror- 
external relation for the upper third and the internal popliteal 
is the relation for the lower two-thirds. 

Branches. 

Muscular Inferior External Articular 

Superior Kxternal Articular Inferior Internal Articular 

Superior Internal Articular Azygfos Articular 

The muscular branches of the popliteal consist of two sets, 
superior and inferior. The superior are several small branches 
g-iven off to the ham-string* inuscles, while the inferior consist 
usually of tv^^o larg^e branches called the sural which are dis- 
tributed to the two heads of the gfastrocnemius 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 front of the 
femur, and a recurrent branch from the anterior tibial. The}'" 
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 mag-na, the inferior internal and external 
articular arteries. 

The superior internal articular, passing" beneath the 
tendon of the adductor mag*nus, winds around above the 
inner condyle of the femur, anastomosing* with the anastomot- 
ica mag*na, the superior external articular, and the inferior in- 
ternal articular. 



350 DESCRIPTIVE ANATOMY. 

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 
tuberosity of the tibia, anastomosing* with the superior internal, 
and inferior external articular arteries, and, across the patella, 
with the superior external articular. 

The azygos articular consists of one or two small branches, 
which, rising- opposite the posterior lig-ament 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. 

^\\^ -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 soleus and descends the back of the leg- with a 
steady inclination inward to the inner aspect of the os calcis 
w^here it divides midway between the internal malleolus and 
posterior tuberosity of the os calcis into the internal and ex- 
ternal 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 surperficial, having- emerg-ed 
to the inner side of the tendo Achilles, because of its ow^n 
inward inclination and because of the narrowing- of the triceps 
surae to a tendon. It lies on the tibialis posticus, the flexor 
iDigas digitoram, the tibia, ani 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 ankle joint from within outward, first is 
the tendon of the tibialis posticus, then the tendon of the flexor 
longus digitorum, these tendons lying in the same groove, 



THE VASCULAR SYSTEM. 351 

next comes the artery with a satellite vein on either side, then 
the posterior tibial nerve and about one-half an inch more ex- 
ternal is seen the tendon of the flexor long-us hallucis. 

Branches. 

Peroneal 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 g-ives off a recurrent branch which 
passes upward to the knee-joint. 

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 betw^een 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. 

Branches. 

Just above the posterior tuberosity of the os calcis the pero- 
neal and posterior tibial arteries are connected by a small 
transverse communicating branch. The peroneal gives mus- 
cular 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 mem- 
brane 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 calcanea)i. 



352 DESCRIPTIVE ANATOMY. 

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 
calcanean, internal malleolar and plantar arteries. 



The internal -plantar, much the smiller of the two terminal 
branches of the posterior tibial, beg^ins where that artery 
bifurcates midway between the posterior tuberosity of the os 
calcis and the internal malleolus and passes forward alonof the 
inner side of the sole to terminate on the inner side of the 
gfreat toe by inosculating- with the dig-ital branch to that toe, 
having" g-iven oflF muscular branches in its course. 

The External Plantar Artery. 
The external plantar, the larg-er and more important of the 
two terminal branches of the posterior tibial, beg-ins where 
that artery bifurcates midway between the posterior tuberosity 
of the OS calcis and the internal malleolus, and passes forw^ard 
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 third layer of the muscles to cross to the 
inner side of the sole and terminate there at the posterior ex- 
tremity of the first interosseous space by anastomosing" with 
a communicating branch from the dorsalis pedis artery. That 
portion of the artery which crosses the sole from the outer to 
the inner side is called the plantar arch. 

Branches. 

Besides muscular branches, the external plantar gives off 
the following- : digital and posterior perforating. 

The digital branches are four in number. They run for- 
ward 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 VASCULAR SYSTEM. 353 

T\iQ posterior pcr/oraii)2g , 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 beg-ins where the popliteal forks, 
at the lower border of the popliteus muscle, beneath the ten- 
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 interos- 
seous 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 lig-ament, by assuming- the name of 
dorsalis pedis. 

Relations. The anterior tibial is divided into three portions, 
upper, middle and low^er thirds. 

In its upper third it lies on the front of the interosseus 
membrane between the tibialis anticus internally and the 
extensor long-us dig-itorum 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 long-us dig-itorum ag-ain 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 ag-ain to the outer side. 

Branches. 

The branches of the anterior tibial artery are muscular, a 
recurrent branch, which ascends to the front of the knee 
throug-h the tibialis anticus muscle, and two malleolar 
branches, external and internal, which surround the tibia just 
above the ankle-joint and supply that joint. 

Des Anat— 23 



354 DESCRIPTIVE ANATOMY. 

The Dorsalis Pedis Artery. 

The dorsalis -pedis artery is the continuation of the anterior 
tibial. It beo"ins beneath the annular lig*ament, about the 
middle 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 the same 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 long-us digitorum, and near its termination it is 
crossed by the tendon of the extensor brevis dig-itorucn 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. 

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 for- 
ward three branches called interosseous, which after receiving* 
the anterior perforating branches of the plantar digital arte- 
ries, 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 second 
toe. 

The communicating passes through the first interosseous 
space to anastomose with the termination of the external plantar, 
giving oif a branch, 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. 



THE VASCULAR SYSTEM. 355 

Internal Iliac Artery. 

The Internal Iliac, 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 vertebra and the 
sacrum, and passes downward into the pelvis over the front 
of the sacro-iliac symphysis to the upper marg-in of the 
g-reat sacro-sciatic notch, where it divides into the anterior 
and posterior trunks. Its leng-th is variable, and is usually 
about two inches. It is a short and wide trunk. 

Relations. It lies behind the peritoneum, has the ureter upon 
its front, and rests behind upon the lumbo-sacral cord and the 
pvriformis muscle and internal iliac vein. On the leftside it 
has resting- upon it the end of the sig^moid 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 ar- 
tery of the foetus is a branch of the internal iliac. It is nearly 
obliterated 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. 

Hypog-astric Obturator 

Inferior Vesical Ischiatic 

Middle Hemorrhoidal Internal Pudic 

Hypogastric. 

The first of these branches, the obliterated hypog-astric, 
passes from the front of the anterior trunk to the posterior 
surface of the bladder. This artery conveys but a small 
amount of blood, which is transmitted to the bladder by two 
small vessels, known as the superior and middle vesical arte- 
ries. Thev are distributed to the apex and g-reater portion of 



356 DESCRIPTIVE ANATOMY. 

tHe body of the bladder, while a small twig- from one is 
generally g-iven to the vas deferens. 

Inferior Vesical. 

The inferior vesical, spring-ing- directly from the anterior 

trunk is distributed to the base of the bladder, and in the male 

subject, passes forward also to the prostate g-land and to the 

seminal vesicles. 

Middle Hemorrhoidal. 

The next branch, the middle hemorrhoidal, which frequently 
arises in common with the inferior vesical, pisses to the rectum, 
and supplies the middle portion of that g-ut, anastomosing- 
above with the superior hemorrhoidal and below with the infe- 
rior hemorrhoidal branches of the internal pudic. 

Obturator. 

The obturator is the larg-est of the way-side branches of the 
anterior trunk. It is very variable in its orig-in. Generally 
the product of the anterior trunk, it sometimes spring-s from the 
deep epig-astric 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 parieta 
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 pelvic 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, anastomo- 
sing there with the pudic branch of the deep epigastric. After 
emerging from the pelvic cavity, it divides into two branches, 
external and internal. 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 inter- 
nal circumflex, the artery supplying the muscles around the 



THE VASCULAR SYSTEM, 357 

tuberosity of the ischium in its course. The internal branch, 
skirting- the inner marg"in of the obturator foramen, supplies 
the muscles around that foramen and the abductor muscles, 
anastomosing- with the internal circumflex and with the 
external division of the obturator. The external branch also 
anastomoses with the ischiatic. 

After g-iving- off the preceding- branches, the anterior trunk 
divides into two terminal branches, the ischiatic, or sciatic, 
and the internal pudic. 

Ischiatic. 

The ischiatic arter}^ leaves the pelvis throug-h the g-reat 
sacro-sciatic foramen below the pyriformis muscle. It descends 
between the trochanter major and the tuberosity of the ischium, 
crossing- the external rotatersof the thig-h, and passing- down- 
ward on the inner side of the g-reat sciatic nerve. It inosculates 
with the internal circumflex and superior perforating- branch 
of the profunda, and g-ives off muscular branches to the mus- 
cles in its course. Besides these, it g-ives coccyg-eal branches 
within the pelvis, which pierce the g-reat sacro-sciatic lig-ament 
to supply the g-luteus maximus muscle; and a rather larg-e 
branch, called \)i\^ inferior gluteal, passing- to the deep surface 
of the same muscle; an articular branch to the hip joint, g-iven 
off external to the pelvis; cutaneous branches to the integ-ument 
of the g-luteal reg-ion; and a branch which accompanies the 
sciatic nerve, called the comes nervi ischiatici. 

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 down- 
ward over -the sacral plexus of nerves, parallel with that 
artery, to leave the pelvis throug-h the g-reater sacro- 
sciatic foramen below the pyriformis muscle. It then con- 
tinues 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 muscle, held 



358 DESCRIPTIVE ANATOMY. 

in position by a fold of the pelvis fascia, until it reaches a point 
opposite the transversus perinsei or near the central point of 
the perineum, where it divides into a superficial and a deep 
perineal branch. 

The su-perficial perineal passes forward through the perineum 
as far as the scrotum. At the upper border of the transversus 
perinsi it gives off a branch bearing- the same name as that 
muscle, which crosses on that muscle, supplies it and the 
adjacent 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 
muscles, anastomosing with the middle hemorrhoidal and with 
the vessels of the opposite side. 

The dee^ -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 inw^ard between the layers of the 
triangular ligament to plunge at once into the bulb of the penis. 

The artery of the corpus cavernosum, 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, 
continues upward between the two layers, lying in the sub- 
stance 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 anastomose 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 anas- 



THE VASCULAR SYSTEM. 359 

tomoses with the deep external pudic branch of the femoral, 
which has been knowm to tike its place. 

Branches of the Posterior Trunk. 

Ilio-Lumbar Lateral Sacral Gluteal 

Ilio-Ivumbar 

The ilio-lumbar is a short recurrent branch, which arising* 
from the postero-external part of the internal iliac, passes 
upward and outward beneath the common iliac artery. It 
passes between the lumbo-sacral cord and the obturator nerve, 
and then beneath the psoas mag-nus muscle ; and divides into 
two branches, iliac and lumbar. 

The iliac brcuich passes betw^een the iliacus internus mus- 
cle and the iliac fossa, is distributed to that muscle, and sends 
a nutrient artery to the bone. 

The lumbar branch, passing- beneath the psoas mag"nus, 
supplies that muscle and the quadratus lumborum, and sends 
a spinal branch into the foramen between the last lumbar 
vertebra and the sacrum. 

Lateral Sacral. 

The lateral sacral are a pair of small arteries, the superior 
of which enters the anterior sacral foramen, where it commu- 
nicates wnth branches of the lumbar arteries above, and with 
branches of the lower lateral sacral below. The inferior pass 
downward on the front of the sacrum, and send a branch into 
each anterior sacral foramen, over which they pass, these 
branches communicating" with one another, and also with the 
superior lateral sacral above. 

Gluteal. 

Th.t finical artery is a continuation of the posterior trunk 
of the internal iliac. It passes backward through the upper 
part of the g-reat sacro-sciatic foramen above the pyriformis 
muscle, usually piercing- the sacral plexus of nerves. After 
emerg-ing- from the pelvis, it divides into two branches, a 
superficial and a deep, the supe7'Jlcial p3iS9,\ug outward between 
the g-luteus maximus and the gluteus medius muscles to sup- 



360 DESCRIPTIVE ANATOMY. 

ply the former, and, perforatino- it, to be distributed to the 
integument. 

The dee^ branch, itself subdividing* into two, runs between 
the g^luteus medius and minimus, and g-ives branches to these 
two muscles. The superior division of the deep branch anas- 
tomoses with the circumflex iliac, and with the external cir- 
cumflex. 

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 beg-ins where that vessel 
terminates on the upper border of the thyroid cartilag-e oppo- 
site the transverse process of the fourth cervical vertebra, and 
passes upward on the frout of the transverse processes of the 
three upper cervical vertebrse to the carotid aperture on the 
basilar surface of the petrous portion of the temporal bone. 
Entering- at this foramen, it abruptly chang-es its course to 
pass inward and forward, with a slig^ht inclination downward, 
running- in the carotid canal, to an aperture of exit near the 
apex of the petrous portion of the temporal, where it ag-ain 
chang-es its direction, passes upward to enter the cavity of the 
cranium, turns forward, lying- in the cavernous g-roove by the 
side of the sella Turcica, and finally passes upward beside the 
anterior clinoid process, and divides into four terminal bran- 
ches. Anterior Cerebral, Middle Cerebral, Posterior Commu- 
nicating-, and Anterior Coroid. 

Relations . Its relations to muscles and structures throug-hout 
its course are as follows: Behind it are the anterior tubercles 
of the transverse process of the three upper cervicle vertebrse, 
separated from the artery by the orig-in of the rectus capitis 
anticus major. In front, it is at first superficial, being- covered 
by the skin, superficial and deep fascia, platysma, stylo-hyoid 
and dig-astric muscles, and at its commencement by the anterior 
border of the sterno-cleido-mastoid. As it ascends, however, 



THE VASCULAR SYSTEM. 361 

it passes beneath the parotid g-land, the stylo-g*lossus and 
st3'lo-pharyng-eus muscles and the stylo-hyoid lig-ament. 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 muscle and posterior belly of the dig-astric muscle, 
the internal passes behind the external and is thenceforward 
separated from it by the stylo-g-lossus and stylo-pharyng-eus 
muscles and stylo-hyoid lig-ament, and b}^ the oflosso-pharyn- 
^•eal nerve, and the pharyno-eal branch of the pneumog-astric. 
Through the greater portion of its course the internal jugular 
vein lies to its outer side, as does the pneumogastric nerve ; 
but near the carotid 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 apertures of entrance, and that the anterior condy- 
loid foramen is behind and internal to this. Hence the rela- 
tions 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 inter- 
nal. The ninth, tenth and twelfth quickly emerge between 
the artery and the vein, while the eleventh passes behind the 
vein. The relation, then, immediately after emergence from 
their respective foramina would be : the artery the most inter- 
nal of all the structures l3^ing against the wall of the phar^'nx, 
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 hypo-glossal, or twelfth, nerve now becomes an antero- 
external relation until it reaches the lower border of the stylo- 
hyoid and posterior belly of the digastric, when it crosses the 
artery directly in front to reach its point of distribution, while 
the pneumogastric, or tenth, continues downward as an ex- 
ternal relation, lying between the artery and the vein. Poste- 



362 DESCRIPTIVE ANATOMY. 

riorly the artery rests upon the cervical portion of the sympa- 
thetic, which separates it from the rectus capitis anticus 
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 throug-h that sinus. 

Branches. 
The first portio)i g"ives off no branches. Th.Q second portion 
produces one unimportant branch, the tympanic, which passes 
to the tympanum. The third portion g-ives origin to three 
branches. Two of these, the arteria receptacnli, are unim- 
portant and are distributed to the cavernous sinus and dura 
mater; the third is an important branch, the opthalmic artery. 

The Opthalmie Artery. 

The opthalmie ar^'erv spring's from the internal carotid about 
the termination of its third portion and passes forward into 
the orbit throug-h 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 to divide at the internal angle of the orbit into two 
branches, /ro«/«/ and nasal. 

Branches. 

The branches of the opthalmie 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 palpebral 
muscle and escaping to the forehead through the supraorbital 
foramen, is there distributed by a superficialand 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 fossae. 



THE VASCULAR SYSTEM. 363 

The -palpebral arteries, superior and inferior, arise from 
the opthalmic near its termination. The superior runs out- 
ward on the upper lid near its free edg-e, between the orbicu- 
laris palpebrarum 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. 

Frontal. 

The/>'6>;//(2/, one of the two terminal branches of the opthalmic 
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. 

Nasal. 

The nasal, the other terminal branch of the opthalmic 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 ce)itralis retince pierces the optic nerve and 
runs forward in it to reach the retina and be there distributed. 

The opthalmic gives off numerous muscular 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 ciliary arteries consist of three sets, viz : 

1st. Short ciliary branches, which are numerous small ar- 
teries which pierce the sclerotic around the optic nerve and 
supply the choroid. 

2nd. Long ciliary, which are two branches piercing the 
sclerotic on opposite sides and running forward between it 
and the choroid to be distributed to the iris. 

3d. Anterior ciliary h'CdLr\.z\\2.'^, which are the offspring of 
muscular branches and pierce the sclerotic near the front of 
the eye to reach the iris. 

The branches from the fourth or cerebral portion are four. 



364 DESCRIPTIVE ANATOMY. 

Anterior Cerebral Artery. 

The anterior cerebral artery, one of the terminal branches 
of the internal carotid, runs forward in the long-itudinal 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 distributed in the interior of the cerebrum. An important 
fact concerning these branches is that they do not anastomose 
with each other in the brain. 

Anterior Choroid Artery. 

The anterior choroid pierces the base of the brain to enter 
the descending cornu of the lateral ventricle and form the 
choroid plexus. 

Posterior Communicating Artery. 

The j^osterior communicati?i§ artery, the last of the four 
terminal branches of the internal carotid, passes backward to 
anastomose with the posterior cerebral of the basilar artery. 



THE VASCULAR SYSTEM. 365 

From this artery are g-iven off g-ang-lionic branches which pass 
throug-h 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. Beg-inning- in front we 
have the anterior communicating-, and, following- the arteries 
back on one side, they come in this order, anterior cerebral, 
internal carotid, posterior communicating-, posterior cerebral 
and the termination of the basilar artery. Following- them 
forward from the basilar artery they come in the reverse order. 



366 DESCRIPTIVE ANATOMY. 



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- mto that org^an by means 
of two main trunks, called the Superior and Inferior Venae 
Cavae, and by small vessels which carry the venous circulation 
of the heart itself. 

The veins are divided into two sets, the superficial and the 
deep. The superficial veins are found between the layers of 
snperficial fascia; and ultimately terminate by emptying into 
the deep veins. The deep veins are found accompanying- the 
arteries, and are arrang-ed in two forms : the smaller arteries 
are accompanied by satellite veins, one upon either side, while 
the larger vessels are accompanied by a sing-le 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 Lozuer Extremity consist of two sets, 
superficial 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 
surface, on both sides of the dorsalis pedis. 



THE VENOUS SYSTEM. 367 

The companion v^ins of the internal and ext(Trnal f>lantar 
arteries, commencing' respectively on the inner and outer side 
of the foot, unite where the posterior tibial artery terminates 
to form two companion veins for the posterior tibial. These 
veins ascend, lying- one upon either side of the posterior tibial 
artery, and recieve, about an inch below the begfinning 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 g-reat toe, receive the veins 
from 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 w^hich 
accompany the branches of the anterior tibial artery, and con- 
tinue 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. 

The Popliteal Vein then passes upward accompained 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 
beg-inning where the femoral artery terminates in the popliteal. 
It receives the accessory veins which accompany the five 
articular branches and the muscular branches given off by the 
popliteal artery, and becomes the femoral vein at the junction 
of the lower third with the upper two-thirds of the shaft of 
the femur. 

The Femoral Vein then accompanies the femoral arter3% 
receiving- 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 
directly behind it, and finally internal to it, so thatat 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 g-ives off its profunda femoris branch, which artery 
is accompanied by its own vein formed by the various satellite 



368 DESCRIPTIVE ANATOMY. 

veins accompanying- branches from the profunda femoris. At 
the orio-in 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 lig-ament terminates by becoming- the 
External Iliac Vein. Just before reaching- Poupart's lig-a- 
ment, the femoral vein, lying- then opposite the saphenous 
opening- of the fascia lata, receives the long- or internal, 
saphenous vein and the satellite veins w^hich accompany 
the superficial branches g-iven off from the femoral in this 
situation. 

After chang-ing- its name to become the External Iliac, 
the vein receives the companion branches of the deep circum- 
flex, and the deep epig-astric 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 lumbar vertebra and the sacrum. 

At this point it is joined by the internal iliac vein, which is 
made up of a larg-e number of satellite veins accompanying- the 
numerous branches of the internal iliac artery. The conflu- 
ence of these two veins forms the Common Iliac, which vein 
is found lying- first directly behind its artery, then external 
and on a plane posterior, 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 Yena Cava. 

This description applies only to the common iliac vein of the 
right side of the body. 0)1 the left side the external iliac vein 
is internal and abreast of its artery at Poupart's lig-ament, con- 
tinues internal, but on a plane posterior to it, up to the bifur- 
cation of the common iliac artery, passes here behind the 
internal iliac, and is joined by the vein accompanying- that 
artery, forming- the Common Iliac Vein of the left side, which 
vein is internal to the common iliac artery throug-hout its 
course; and finally passes behind the rig-ht common iliac artery 



THE VENOUS SYSTEM. 369 

to join with that vein opposite the fourth lumbar vertebra and 
form the inferior vena cava. 

Internal Iliac Vein. 

The i)iter)ial 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. 

The 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 verte- 
bra, 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 suprarenal veins, and con- 
tinuing 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 open- 
ings found in the diaphragm; and entering the base of the 
heart at the lower, inner, and back p«.rt of the venous auricle, 
pours its current into that organ. 

The Portal System. ' 

The l)lood 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 veins in which the capillaries of the hepatic artery termi- 

Des Anat— 24 



370 DESCRIPTIVE ANATOMY. 

nate, while a part of it is the product of the portal system of 
veins, which drain the circulation of a larg-e 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 receives a double blood supply, one portion bein^ 
that received from the hepatic artery, the ordinary arterial 
blood, which is intended for the nutrition of the liver tissue 
itself (parenchyma), the other derived 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 the 
necessary changes in the blood before it is conveyed to the 
circulation. 

This Portal System of Veins is formed in the following 
manner: the -portal vein commences at the upper border of the 
pancreas by the union of the splenic and the superior 7nesen - 
teric veins. The splenic vein, before uniting with the superior 
mesenteric, receives behind the pancreas the inferior mesenteric 
vein, this vein conveys the return circulation from the sig- 
moid flexure of the colon, and the descending colon. The 
superior mesenteric vein carries the return circulation from the 
transverse colon, descending colon, coecum, and small intes- 
tines. 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 g'as- 
iric veins, one of which accompanies the gastric artery and 
the other the arch formed by the inosculation of the gastro- 
epiploica dextra and sinistra, empty into the portal system, 
which also receives the small vein which accompanies the 
pancreatica magna artery and the pancreatico-duodenalis su- 
perior. The vein which accompanies the pancreatico-duode- 
nalis inferior empties into the inferior vena cava before that 
reaches the splenic vein. 



THE VENOUS SYSTEM. 371 

The Sflenic itself is formed by vessels which conve}^ the 
return circulation from the spleen; and also receives the small 
veins accompanying the various branches given to the pan- 
creas 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 edge of the lesser omentum. It lies behind the hepatic 
artery and common bile duct ; but opposite the interval be- 
tween these tvv^o 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 
surrounding 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 
Pa mp in if or 771 Plexus (L. Pa77ipi)ms, a tendril; /or77ia, like). 
They then pass upward with the other elements of the sper- 
matic cord. Entering at the superficial abdominal ring, the}^ 
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. 

0)1 the 7'ighi side, the vein passes across the external iliac 
artery, gets to the outer side of that vessel ; and passing upward 
with a steady inclination inward, terminates by entering at an 
acute angle into the inferior vena cava, the blood from the sper- 
matic vein going in the same direction as the blood from the 
vena cava. 



372 DESCRIPTIVE ANATOMY. 

On the left side, it crosses the termination of the internal 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 testicle and scrotum 
so frequently occurs, the surgical disease known as variocele 
arising from this cause. 

The Superficial Veins of the Lower Extremity. 

Returning to the lower extremity, we find that there are 
certain 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, 
extending entirely across the foot near the web of the toes. 

The Short Sa-phenous 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, accompan3'ing 
the nerve of the same name. As it passes upward, it gradually 
wnnds 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 terminates by emptying into the 
popliteal vein. 

The Long- Saphenous 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 cribriform fascia, and 
terminates by emptying into the femoral vein. Occasionally 



THE VENOUS SYSTEM. 373 

before emptying' into the femoral the long- saphenous 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 aper- 
tures which they make through the fascia covering- the saphe- 
nous opening" g-iving- it its cribriform appearance. 

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 larg"e and so 
numerous 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 
commence as the companion veins of the superficial palmar 
arch, orig-inating- in veins which accompany the dig-ital 
branches of that arch. This arch receives the interosseus 
veins ; and forms on either side the vena^ 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 satel- 
lite veins of the radial form the external satellite veins of the 
brachial, while the satellite veins of theulnar form the internal 
satellite veins 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 follows the course of 
the axillary artery, lying- to its inner front aspect throug-hout 
the course of that vessel, receiving- tributaries from the veins 
accompanying- branches of that vessel, the larg-est and most 
important of which are the companion veins of the sub-scapular 
artery, and terminates at the outer border of the first rib by 
becoming- the subclavian vein. This vein then continues its 
course to join the internal jug-ular, and form the innominate 
vein. 



374 DESCRIPTIVE ANATOMY. 

The Superficial Veins of the Upper Extremity. 

Anterior Ulnar Radial 

Posterior Ulnar Median 

Common Ulnar Basilic 

Cephalic Median Basilic 

Median Cephalic Subclavian 

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. 

The Common Ulnar. 

The Comvion Ulnar Fi?/;? ascends to the inner side of the front 

of the elbow to unite with the median basilic vein 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 con- 
tinues to ascend until it reaches a point about an inch below 
the elbow joint, where it unites with the median cephalic to 
form the cephalic vein. 

The Median Vein. 

The Median Vein is a small vessel which receives the blood 
from the middle of the palm of the hand. It is scarcely per- 



THE VENOUS SYSTEM. 3/D 

ceptible until just above the wrist joint, where the formation 
of the vein may be said to take place. It then passes directly 
upward, 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 respec- 
tiveh' the Median Basilic and the Median Cephalic. 

The Median Basilic. 

The MedicDi Basilic Vein unites with the common ulnar, 
the product of the anterior and posterior ulnar veins, to form 
the basilic. 

The Median Cephalic. 

The Media)i Cephalic Vein unites with the radial vein to 
form the cephalic vein. 

The Basilic Vein. 

The Basilic Veiii, formed below the elbow joint by the 
union of the common ulnar with the median basilic, passes 
upward and crosses over the bicipital slip of fascia g-iven off 
from the tendon of the biceps to the fascia of the inner side of the 
forearm. It then lies to the inner front aspect of the brachial 
artery to about the middle of the course of that vessel, sep- 
arated from it by the deep fascia, where its relation is chang-ed 
only to the extent of lying- beneath the investing- fascia. That 
is, up to the middle of the brachial artery the basilic vein is 
superficial to the investing- fascia ; but opposite the middle of 
that vessal it pierces this fascii, 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 termi- 
nates by uniting with the internal satellite vein of the brachial 
just before the latter unites with the external satellite to form 
the axillary vein. Some authorities describe the basilic as re- 
ceiving- the two satellite veins of the brachial and becoming- 
the axillary vein. 

The Cephalic Vein. 

The Cephalic Vein, formed below the middle of the elbow 
joint by the union of the radial and the median cephalic, 



376 DESCRIPTIVE ANATOMY. 

passes upward and outward until it reaches the interval be- 
tween the brachialis anticus and the supinator long-us and ex- 
tensor carpi radialis lonofior. It then passes upward in a 
g-roove found on the outer aspect of the arm, caused by the 
bulg-ing- 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 g-roove between these two muscles, it 
passes over the fibrous-covered interval between the muscles 
and empties into the axillary vein just before its termination 
in the subclavian. Before the cephalic vein enters the axil- 
lary it receives a communication from the external jug-ular 
vein of the neck. 

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 ax- 
illary artery throug-h the axillary space, receives the tributaries 
which accompany the branches of that vessel; and continually 
increases in size until it reaches the outer border of the first 
rib behind the junction of the outer third with the inner two- 
thirds of the shaft of the clavicle, where it terminates 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 anterior to 
the corresponding- artery, so that it is anantero-internal 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 suprascapular and transversa colli 
arteries. These veins usually unite before entering- the 
subclavian; but occasionally enter by separate opening-s. The 



THE VENOUS SYSTEM. 377 

external jug-ular 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, internal mammary, 
and vertebral arteries, and terminates behind the sterno- 
clavicular articulation by unitingf with the internal jug-ular to 
form one of the innominate veins. 

The Veins of the Head and Neck. 

The Veiiis of the Head consist of a set of channels found in 
the cranium, formed by divisions in the dura mater, and called 
"sinuses", while the veins of the neck are described under the 
name of "jug"ular" veins {Lt. Jug-nluni — diminutive of jiigum, 
the yoke — the throat), of which, however, there are three: the 
Internal, External, and Anterior Jug"ular. In addition to 
these jugular veins there are smaller veins, such as the thyroid 
and the vertebral, which durino- a portion of their course are 
found Ijnng- in the neck. Certain veins are also found upon 
the face, which aid in forming- the jug"ulars. 

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 which pass through 
foramina such as the mastoid and parietal. 

The Sinuses of the Dura Mater. 

Superior Longitudinal Inferior Longitudinal 

Straight Lateral 

Cavernous Occipital 

Superior Petrosal 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 
Diphe lying between the two tables of which the bones of the 
skull are composed, while the other set, the Cerebral veins, 



378 DESCRIPTIVE ANATOMY. 

are found ramifying- over the surface and in the interior of the 
encephalon. The Cerebral Veins consist of two sets, super- 
ficial 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 ventricu- 
lar veins, the Venae Galeni, which leave the interior of the 
brain throug-h the g-reat transverse fissure and terminate in 
the straig-ht sinus. 

The Snperior Longitudinal Sinus, 

The Superior Long-itudinal Siruis commences at the fora- 
men caecum, where it communicates with the small veins of 
the nasal fossa. The g-roove along which it rnns may be dis- 
covered on the dried bones as occupying- the mid-line of the 
frontal bone, and g-rooving- equally the upper border of the 
two parietal bones. Leaving these b^nes, it appears on the 
occipital, grooves it in the mid-line, and pisses backward to 
the torcular Herophili by the side of the anterior occipital 
protuberance, to diverg-e 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 spice between 
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 g-roove, this 
sinus receives the superficial cerebral veins. 

The Inferior Longitudinal Sinus. 

The Inferior Longitudinal Sinus is a small sinus, circular 
on cross-section (unlike the superior, which is triang-ular on 
cross-section). It commences near the anterior extremity of 
the falx major, follows the curvature of that subdivision of 
the dura miter, and passes backward to the junction of the 
falx major with the tentorium cerebelli, where it empties into 
the straig-ht sinus. 

The Straight Sinus. 

The Straight Sinus runs in the triang-ular interval between 
the falx major and the tentorium, to terminate in one of the 



THE VENOUS SYSTEM. 379 

lateral sinuses. Before receiving* the inferior 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 vein around the foramen magnum, 
and is situated in the attached marg-in of the falx cerebelli, 
communicating- 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 opthalmatic veins from the sphenoidal fissure. The 
opthalmic veins, following- the course of the opthalmic 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 
tog-ether 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 bor- 
der of the petrous portion of the temporal. Its inner extremity 
is connected with the cavernous sinus, while its outer is 
connected with the lateral sinus, just as that sinus reaches the 
inner face of the mastoid portion of the temporal, and receives 
the mastoid veins. 

The Inferior Petrosal Sinus. 

The Jnfcrior Petrosal Sinus occupies the groove between 



380 DESCRIPTIVE ANATOMY. 

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 Simtses commence at the torcular Herophili, 
where the long-itudinal 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 rig^ht. The blood from the 
superior long-itudinal sinus pours into the lateral sinus of the 
rio-ht side, while the current of blood from the occipital and 
straig"ht sinuses usually passes into the opposite lateral sinus. 

The lateral sinus of each side arches outward along the 
anterior face of the occipital bone; but leaves that bone to 
appear momentarily on the postero-inferior asg-le of the parietal. 
Leaving- 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 sigmoidea and finally at the posterior extremity of the 
jugular (the foramen lacerum posterius), it unites wnth the 
inferior 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 lougitudinal sinus, 
which, in its turn, receives the superficial cerebral veins, w^hile 
the left internal jugular conveys most of the blood carried by 
the venaj 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 
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 estab- 
lish an inflammation of the brain itself. 



THE VENOUS SYSTEM. 381 

The Internal Jugular. 

The Liternaljiignlar F^/;/, formed, as above described, by the 
union of the inferior petrosal with the lateral sinus, is a larg-ely 
dilated 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 ar- 
ter}^ with the twelfth, or hypo-glossal, nerve behind 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 relation of the internal carotid to the 
point at which that vessel is derived from the common carotid 
artery ; then becomes a 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 join- 
ing the subclavian vein to form the innominate vein of thatside. 
In its course down the neck, the glosso-pharyngeal and hypo- 
glossal nerves pass forward between the artery and the vein, 
to 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 internal relation of the internal jugular through- 
out the entire course of that vein. 

Its tributaries are the Facial, Lingual, Pharyngeal, Super- 
ior and Middle Thyroid Veins. 

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 unite, 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 corresponding side. 

The Veins of the Face. 

The Veijis of the /^«6'6' consist of numerous branches, which 
correspond to the arteries of the face. Of these, the Supra- 



382 DESCRIPTIVE ANATOMY. 

orbital commencing- 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 communi- 
cation from the tempero-maxillary vein, and empties into the 

internal jug-ular. 

The Temporal Veins. 

The Tenifioral Veins commence on the lateral aspect of the 
skull by numerous tributaries, pass downward in an interval 
between the internal auditory meatus and the tempero-maxil- 
lary articulation, run into the substance of the parotid g-land, 
and receive the internal maxillary vein, made up of tributa- 
ries accompanying" branches of the internal maxillary artery, 
and behind 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 jug-ular, while the other unites with the pos- 
terior auricular to become the external jug"ular vein. 

The External Jugular. 

The External Jug-ular Vein, commencing* in the substance 
of the parotid g-land, receiving- the g-reater portion of the blood 
from the exterior of the cranium and the deep parts of the face, 
runs down the neck in the direction of the fibres of the platysma 
myoides muscle, which covers it. It runs nearly parallel 
w^ith the posterior border of the sterno-cleido-mastoid muscle 
until it reaches a point just above the clavicle, where it 
chang-es its direction, and passing- downward and inward, 
empties into the subclavian 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 
described as formed behind the rig-ht sterno-clavicular articu- 



THE VENOUS SYSTEM. 383 

lation by the union of the subclavian and internal jugular veins. 
0)1 the left side the vein is formed in the same way ; but 
usually the internal jugular lies to the outer front aspect of 
the left subclavian arter}', 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 and anterior to the innominate artery, 
and a little to the right side of that vessel. On the left, the 
innominate 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 commencement of the transverse 
aorta the two innominate veins unite to form the Superior Vena 
Cava. 

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 front 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, accompanying the artery of 
the same name, pass likewise into the corresponding innominate 
veins. 

The Superior Intercostal Veins, returning the blood from 
the upper intercostal spaces, except the first, empty, the right 
one into the vena azygos major, the left usuall}" into the left 
innominate vein. 

The A2yfi'os Vei?is connect the superior and inferior venae 
cava,'. They are two in number, the right azygos, or vena 
azygos major, and the left azygos, or vena azygos minor. 

The Vena Azygos Major. 

^):\{t Azygos ^^/tt/V^r commences in the abdominal cavity oppo- 



384 DESCRIPTIVE ANATOMY. 

site the first or second lumbar vertebra, sometimes from the 
first lumbar vein, sometimes by a branch from the renal vein. 
It enters the thorax throug-h the aortic opening- of the diaph- 
ragm; and receiving- branches from the lower six intercostal 
spaces, finally terminates by crossing the vertebral column 
opposite the sixth dorsal vertebra behind the thoracic aorta, 
and empties into the superior vena cava just before that vessel 
passes into the heart. 

The Vena Azyg-os Minor. 

Just before the azygos major crosses the vertebral column 
it is joined by the Vejia Azyg-os Minor, which conveys the 
blood from the intercostal spaces between the superior azygos, 
already described as the Left Superior Intercostal, and the 
highest branches entering into the azygos minor. 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, 
however, the communication consists entirely of a brancH from 
the renal vein, w^hich in its turn empties into the inferior vena 
cava, and thus indirectly establishes this communication. 

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 meduUi-spinal are numerous veins ramifying beneath 
the arachnoid membrane of the spinal cord. 



THE VENOUS SYSTEM. 385 

The Cardiac Veins. 

The veins of the heart are two, as follows : 

The Great Cardiac Vein. 

The great cardiac vein ascends in the anterior ventricular 
g-roove, winds around the left auriculo-ventricular g-roove and 
opens into the rig-ht 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 g^reat cardiac vein. 

Des Anat — 25 



386 DESCRIPTIVE ANATOMY. 



THE LYMPHATIC SYSTEM. 

The lymphatic system consists of numerous small vessels 
ramifyinof in nearly every tissue of the body, and of small, 
reddish, pea-like bodies called h^mphatic g^lands, found at 
intervals 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 ; consequently the course of their circulation is from 
the circumference 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 benseth 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 g-reater 
portion of the lymphatics of the body converg-e to form one 
larg-e vessel, the thoracic duct, which empties into the venous 
current near the heart. 

Thoracic Duct. 

The thoracic duct beg-ins on the front of the body of the 
second lumbar vertebra by a considerable dilatation called 
receptaculum chyli, which, narro\ving- to a tube the size of a 
g-oose quill, ascends the front of the vertebral column behind 
the descending- aorta, passes throug-h the aortic opening- of 
the diaphrag-m and continues upward as hig-h as the fourth 
dorsal vertebra, w^here it inclines to the left and continues 
thence an oblique ascent behind 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 commence- 
ment of the left vena innominata. Opening into the commence- 
ment of the rig-ht vena innominata is another and much smaller 
lymphatic duct (ductus lymphaticus dexter) which conveys 
lymph furnished it by the right upper extremity and rig-ht 
side of the head and neck. 



THE LYMPHATIC SYSTEM. 387 



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 lig-- 
ament, they then pass throug-h a set of lymphatic g-lands. 
The deep lymphatic vessels accompany the deep veins upward 
to the g-roin, where they are connected with a set of g-lands, 
lying- beneath the fascia lata and superficial muscles, called 
the deep lymphatic g-lands of the g-roin. Along- the course of 
these vessels are found a few g-lands, some in the popliteal 
space and one on the front of the interosseous membrane of 
the leg-. The lymphatic vessels from the external organs of 
g-eneration and from the abdominal parietes can be traced to 
a third set of g-lands, which form a chain along- Poupart's 
ligament, lying- superficial and above the g-lands around the 
saphenous opening-. 

All these vessels pass beneath Poupart's lig-ament 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 lig-ament are lymphatic g-lands. The 
lumbar lymphatics ascend along- the aorta, constantly increas- 
ing in size by accessions from the abdominal viscera, and 
having- passed throug-h numerous g-lands, and lessened in 
number as they increased 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 dig-estion, 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 



388 DESCRIPTIVE ANATOMY. 

accompany the deep veins, both converg-ing- to the arm pit 
where there are some twelve or fifteen lymphatic glands. 
Besides the vessels from the upper extremity these g-lands also 
receive those from the chest wall and mammary g-land. A few 
g-lands 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 g-lands the vessels proceed along- the course 
of the subclavian vein, opening on the left side into the termi- 
nation 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 jug-ular veins, no lymphatics, however, being- found 
in the substance of the brain. 

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 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-, some portion 
of the thoracic parietes, diaphrag-m and even some 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 lung-s pass through a 
set of glands situated around the bifurcation of the trachea 
called the bronchial glands. 



THE CENTRAL NERVOUS SYSTEM. 389 



THE CENTRAL NERVOUS SYSTEM. 

Cerebro- Spinal Centres. 

The chain of nervous centres known as the Cerebrospinal 
axis is divided into two portions, one contained in the spinal 
canal, and called the spinal cord, or Medulla Spinalis (L. Me- 
dins, middle), the other contained in the cranium and called 
the Brain, or Encephalon, the latter name including the brain 
and its membranes. 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. 

Delicate mother), lying next to the brain ; and the Arachnoid 

between the two. 

The Dura Mater. 

The Dura Mater is a grayish white, strong, fibrous mem- 
brane which lines the inner surface of the cranial wall, adher- 
ing closely to the bone, and supplying the place of an internal 
periosteum. Its internal surface is glistening and smooth 
because lined by the arachnoid, which performs the functions 
of a serous membrane. Besides lining the interior of the cra- 
nial 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 interior of the cavity. These processes 
are three in number : the Falx Major, or Falx Cerebri, the 
Tentorium Cerebelli, and the Falx Minor, or Falx Cerebelli. 
The Falx Major (L. Falx,^ 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 pro- 
tuberance, and is attached to the superior surface of the 
tentorium along its middle line. Along its attachment to the 



390 DESCRIPTIVE ANATOMY. 

cranium, the Falx major divides into two layers, which are 
attached to the marg-ins of the g-roove found on the frontal, 
parietal, and occipital bones. Between these two layers is a 
triangular space, which lodg^es one of the important sinuses, 
the siifierior long-itudiiial sinus. The concave lower margin 
is hollowed out into a small canal, circular 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 
posterior occipital protuberance, and passing- transversely 
forward, extends into the g-reat transverse fissure of Bichat 
separating- the cerebrum from the cerebellum, serving- to sup- 
port the posterior lobes of the cerebrum and at the same time 
to bind the cerebellum in the cerebellar fosss. 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 marg-in 
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 appearance, 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. Between these attach- 
ments is left an opening- through which is transmitted the 
mid-brain. 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 
temporal is another sinus, the superior petrosal ; and where 
the falx major is attached on the superior surface of the ten- 
torium is found a third sinus, the straig-Jit sinus passing back- 
ward to the torcular Herophili. 

The Falx Cerehelli is a small narrow process of the dura, 
which extends from the margin of the foramen magnum 



THE CENTRAL NERVOUS SYSTEM. 391 

Upward to the under surface of the tentorium to the posterior 
part of which it is attached, at the anterior occipital protuber- 
ance. It projects between the two lobes of the cerebellum, 
and serves to separate them from one another. 

The Arachnoid. 

The Arachnoid^ like all serous membranes, presents a 
closed sac, one of its layers lining- the inner surface of the 
dura, and being- called the parietal layer, while the other 
invests the brain, from which it is separated by the pia, and 
is called the visceral layer. It does not dip into the sulci of 
the brain ; but leaps from convolution to convolution, so that 
a space is interposed at various portions of the brain between 
the arachnoid and the pia mater. This space has received the 
hybrid name of Sub-Arach)ioidean. It-can be easily demon- 
strated 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 ag-ain in the 
great transverse fissure of Bichat the space can be easily made 
apparent. 

The Pia Mater. 

The P/« J/«/6'r is an extremely thin and very vascular mem- 
brane, consisting almost entirely of small interlacing- bloodves- 
sels, held tog-ether 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 throug-h the g-reat transverse fissure of Bichat, covering- 
not only the cerebellum and the under surface of the cerebrum; 
but continuing- through this fissure, it passes even into the 
interior of the brain itself, so that prolong-ations of the pia are 
found in the ventricles, in the interior of the hemispheres, 
and connecting with the blood vessels which perforate from 
the base of the brain and supply the structures in the interior 
of each hemisphere. 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 frec^uent elevations and depressions forming- 



392 DESCRIPTIVE ANATOMY. 

the convolutions and sulci would show that if this membrane 
were stripped off, its area would be enormously g-reater than 
the apparent area of the brain itself. E^very sulcus into which 
the membrane dips forms a corresponding- fold, so that it bears 
a close resemblance in its folds to a dress or other garment 
which has been taken out of a trunk. 

The Brain. 

The Ence-phalon is divided into four parts: the Cerebrum, 
the Cerebellum, the Pons Varolii, and the Medulla Oblongata, 
the Pons and its appendages being frequently described as 
the iJiid-brain. 

The zveight 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 w^eight 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 intellectuality varies more with the variety 
and number of the convolutions, and consequently with the 
amount of "gray matter," 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 depres- 
sions which separate these convolutions from one another, 
from the fact that they appear at an early stage of foetal life, 
are called "primary fissures," and from these primary fissures 
we get the great subdivisions of the cerebrum. These pri- 
mary fissures are the Great Long-itiidiiial Fissure^ the Great 
Transverse Fissure of Bichat, the Fissure of Sylviiis, the 
Fissure of Rolando, and the Parieto-occipital Fissure. The 



THE CENTRAL NERVOUS SYSTEM. 393 

_g-)-eat lo)i§iti(di)ial Jissitrc serves to separate the two lobes of 
the cerebrum ; the trcDisvcrsc /iissi(7'c of Bichat to separate 
the cerebrum from the cerebellum ; the^'^^^rr^^ of Sylvius to 
separate the frontal from the tempero-sphenoldal, and by its 
horizontal limb, the parietal from the tempero-sphenoidal ; 
the fissure of Rolando to separate the frontal from the parie- 
tal ; 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 beg-in 
with the five principal, or primary, fissures. 

The Great Lo)igitudinal 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 
cerebrum 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 
there than in front. 

The Fissure of Sylvius. Commencing- on the base of the 
brain near the g-reat long-itudinal 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 tempero-sphenoidal lobes. On leaving- 
the base of the brain to appear on the outer surface of the 
hemisphere, chang-es its direction and passes upward and 
backward, forming- what is called the horizontal limb of the 
fissure of Sylvius, which separates the tempero-sphenoidal 
below from the parietal above. The liorizoiital li))ib of the 
fissure of Silvius extends backward as far as the commence- 
ment 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 hemisphere, 
the vertical limb is g-iven off, which ascends in the convolutions 
of the frontal lobe, forming- in this situation an overhang-ing- 
appearance, which is described as the Operculum {L. Operire, 
to cover.) 



394 DESCRIPTIVE ANATOMY. 

The Fissure of Rolando is situated about the middle of the 
outer surface of either hemisphere. It beg-ins near the lono-i- 
tudinal fissure and runs first downward and forward about 
one-half 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 horizontal and its 
vertical limbs. 

The Parieto- occipital Fissure is but slig^htly seen on the 
outer surface of the hemisphere, the main portion of the fissure 
lying- on the inner face. It commences beneath the g"yrus 
fornicatus opposite the splenium of the corpus callosum ; and 
passes upward and forw-ard to emerge on the outer surface of 
the hemisphere, just in the g-reat longitudinal fissure. 

By these primary fissures the hemisphere is divided into five 
lobes, frontal, parietal, occipital, tempero-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 g-reat long-itudinal fissure, on the outer surface, 
behind, by the fissure of Rolando, on the lower surface, behind, 
by the main portion of the fissure of Sylvius. It should be 
noted that the inner face of the various lobes of each hemi- 
sphere 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 throug-hout the entire leng-th of the hemisphere. 

The Parietal Lobe is bounded above by the great longitudi- 
nal fissure, in front by the fissure of Rolando, below by the 
horizontal limb of the fissure of Sylvius, and a line connecting 
this with the lower end of the superior occipital sulcus, and 
behind by the parieto-occipital fissure and a line drawn in 
continuation of that sulcus. This fissure lies mainly on the 
inner face of the hemisphere, 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 Pari- 
eto-occipital fissure from the parietal lobe, this fissure being- 
its anterior boundary. Above it is bounded by the longitudi- 



THE CENTRAL NERVOUS SYSTEM. 395 

nal fissure, while below its convolutions run into the convolu- 
tions of the parietal and tempero-sphenoidal lobes, there being- 
no fissure to form a separation. 

The Temi)oro-sj)henoidal Lobe is that portion which lies in 
the middle fossa of the skull. On the inferior surface of the 
base of the brain it is bounded in front by the fissure of Syl- 
vius ; externally, it is bounded above by the horizontal portion 
of the fissure of Sylvius ; while posteriorly it blends around 
this horizontal limb of the fissure of Sylvius with the occipital 
and parietal lobes. 

The Island of Rcil is a cluster of five or six convolutions, 
situated 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. 

The Convolutions and Sulci of the /^r<9;z/rt/Zo<^^ are usually 
described as consisting^ of two sets, those found on the exter- 
nal surface, and those on the inferior surface, which is fre- 
quently described 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 fissure of Rolando, and running- 
parallel with it, is a sulcus of the same character, but of less 
depth. This is called the prccoitral sulcus. It commences 
near the bifurcation of the fissure of Sylvius and passes 
upward nearly to the g-reat long-itudinal 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. Two small sulci extend 
forward from near the precentral sulcus. Sometimes 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 -^l^ first, seco/id, and third fron- 
tal convolutions, or occasionally as superior middle, and 
inferior frontal convolutions. If these convolutions be traced 
around to the inferior surface of the frontal lobe, it will be 
seen that here also are three convolutions, sometimes described 
as they/r67, second, and third orbital co}ivolutions, numbered 



396 DESCRIPTIVE ANATOMY. 

from within outward and backward ; but in reality the con- 
tinuation of the first, second, and third frontal convolutions. 
On the orbital surface, close to the g-reat longitudinal fissure, 
is a narrow but deep sulcus, which lodg-es the olfactory nerve. 
External to this is another sulcus, less well-marked, which is 
the external boundary of the first orbital convolution, the con- 
tinuation of the first frontal. The second sulcus, marking off 
the second and third orbital convolutions, or middle and infe- 
rior frontal convolutions, runs transversely, and is usually 
divided into two or more limbs, so that the second orbital con- 
volution lies in front of the third. 

The ascending- frontal convolution begins below near the 
bifurcation 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 con- 
volutions are nearly always united around the upper end of 
the Rolandic fissure. 

The first, or superior, frontal convolution is limited above 
by the longitudinal fissure and below by the first frontal sul- 
cus. It passes directly forward from the precentral sulcus, 
around the upper end of which it is connected with the ascend- 
ing frontal convolution, and, winding around the anterior 
extremity of the frontal lobe, becomes continuous with the 
so called first orbital convolution. On its orbital surface this 
convolution is marked by a deep antero-posterior sulcus — the 
olfactory. 

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 orbi- 
tal 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 



THE CENTRAL NERVOUS SYSTEM. 397 

posterior extremity of that sulcus, with that convolution. It 
is very short and does not reach the anterior extremity of the 
hemisphere, but winds around its outer aspect to become con- 
tinuous with the third or posterior orbital convolution. 

The Convolutions of the Pai'ietal Lobe are the Ascending" 
Parietal, the Superior Parietal, and the Inferior Parietal. 

The Ascending- Parietal 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 tog-ether. Commencing" above the fissure 
of Sylvius, it passes upward and backward parallel with and 
behind the fissure of Rolando to near the g-reat 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 whole is called the Intraparietal 
Sulcus. This may consist of three separate and distinct sulci, 
or any two of these may be united, and the third one exist as 
a separate sulcus. 

That portion of the lobe which is bounded in front b}^ the 
fissure of Rolando, and behind by the ascending" portion of the 
post-central sulcus is called the ascending parietal convolution. 
That portion between the g"reat long"itudinal fissure above, the 
horizontal portion of the post-central sulcus below, and the 
external portion of the parieto-occipital fissure behind, is called 
the superior parietal convolution. That part which lies be- 
tween the horizontal limb of the fissure of Sylvius below, and 
the intra-parietal sulcus above and in front, is called the inferior 
parietal convolutioji. This inferior parietal convolution is 
frequently divided by a small secondary sulcus into two por- 
tions, an anterior lying" above the fissure 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 convolution. 

It will be seen that the fissure of Rolando reaches neither 
the g-reat longitudinal fissure nor the fissure of Sylvius, hence 



398 DESCRIPTIVE ANATOMY. 

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 frontal convolution communicates with theascend- 
ing 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 Convohitions of the Occipital Lobe are three in number, 
superior, middle, and inferior. These convolutions are separa- 
ted by tw^o sulci, called the superior and middle occipital 
sulci. 

These sulci are indistinct and poorly marked, each extend- 
ing backward on the occipital lobe, the convolutions being 
named from above downward. First, Second, and Third, or 
Superior, Middle, and Inferior. The superior occipital con- 
volution is connected with the parietal lobe ; the middle and 
inferior with the temporo-sphenoidal lobe. 

The Convolutions of the Temporo-Sphejioidal Lobe. This 
lobe is divided by three sulci into five convolutions, though 
two of these convolutions are found on the inner surface of the 
hemisphere. The two sulci found on the outer surface are 
the superior, or parallel sulcus and the middle, or second tem- 
poral, 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. 

Ti\lq. first temporo-sphenoidal convolution 'v^ bounded above 
by the horizontal limb of the fissure of Sylvius, and below by 
the parallel sulcus. At its posterior extremity it is continuous 
vs'ith the ang'ular gyrus of the parietal lobe. The second 
teniporo-sphenoidal convolution lies between the parallel sul- 
cus and the second temporal sulcus, and is continuous poste- 
riorly with the angular gyrus of the parietal and the second 
occipital convolution. 

The third temporo-sphenoidal, lying below^ the second tern- 



THE CENTRAL NERVOUS SYSTEM. 399 

poral sulcus, is continuous posteriorly with the third occipital 
convolutton. 

The Island of Rcil. On reaching;- the operculum a o-roup 
of five or six convolutions (thouo-h as few as three have been 
observed)are found lyincr in the interval between the diverg-ing- 
limbs of the fissure of Sylvius. These convolutions constitute 
the island of Reil. The sulci are only slig-ht depressions, and 
the convolutions slig-ht elevations. They all run in the same 
direction, upward, backward, and inward. 

Sulci and Convolutions on the Internal Face of the ^ 
Hemisphere. 

The Calloso-mar^inal 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 jgenu, thence backward, parallel 
with the body of the corpus callosum, until it reaches the 
posterior third of the brain, when it abruptly turns upward 
and passes to the g-reat long-itudinal fissure. 

The Parieto-occipital, the second sulcus found on the inner 
face, begfins at the splenium of the corpus callosum, and passes 
upward and backward to terminate on the external face of the 
hemisphere. 

The Calcarine Fissure, or Sulcus, 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 for- 
ward, with a slight inclination downward ; and joins the 
parieto-occipital sulcus at an acute ang-le. 

The Collateral Sulcus. The fourth is a long- sulcus which 
extends across the inner face of the temporo-sphenoidal lobe, 
separating- the fourth and fifth temporo-sphenoidal convolu- 
tions. It is called the Collateral Sulcus. 

The Dentate Sulcus, the last one, passes beneath the splen- 
ium 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, 



400 DESCRIPTIVE ANATOMY. 

or Calcar Auis (L. A bird's spur), in the posterior horn of the 
lateral ventricle. The collateral sulcus forms the eniinentia 
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 con- 
volution, the g"yrus fornicatus, the quadrate lobe, the cuneate, 
the uncinate g-yrus, and the fourth and fifth temporo-sphenoidal 
lobes. 

The Marg-inal Convolution is the inner face of the frontal 
lobe. It commences at the anterior parf orated space, follows 
the winding's of the calloso-marg-inal sulcus, then runs forward 
beneath the rostrum of the corpus callosum, winds upward 
around the g^enu, and passes backward until the calloso-mar- 
ginal sulcus turns upward to the g-reat longitudinal fissure, 
where the convolution terminates, and is separated from the 
parietal lobe by the end of this sulcus. It will be seen that 
this convolution corresponds to the inner face of the first orbi- 
tal, the first frontal, the ascending frontal and ascending 
parietal convolutions. 

The Gyrus Fornicatus . Below the marginal convolution 
and between the calloso-mirginal sulcus and the corpus cal- 
losum is the Gyrus Fornicatus , or convolution of the corpus 
callosum. It follows the same course as the preceding sulcus 
until it reaches the posterior extremity of the corpus callosum, 
where it blends with the quadrate lobe, winding around the 
splenium of the corpus callosum. Here it changes its name 
to become the uncinate, or hypocampal, convolution. 

The .Quadrate Lobe 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 longitudi- 
nal fissure ; 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 occipi- 
tal convolutions. 



THE CENTRAL NERVOUS SYSTEM. 401 

The Hippocanipal, or Uiicinate, Lobe (L. Unciiius, hooked) 
is a continuation downward and forward of the gyrus foruica- 
tus. It is bounded above by the dentate fissure, and below by 
the collateral fissure. It extends as far forward as the com- 
mencement of the fissure of Sylvius; and innerwards to the point 
where the g'yrus fornicatus commences. Here it turns back- 
ward upon itself, forrainof the hook-shaped appearance which 
g-ives the convolution its name. It is the fifth temporo-sphe- 
noidal convolution, the fourth temporo-sphenoidal lying- beneath 
the collateral sulcus. 

In addition to these convolutions, when the hemispheres are 
separated by cutting' throug-h 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 irreg-ular 
in outline, because it is fitted into the fossae of the skull. 
A^teriorl^^ on either side, is seen the orbital face of the frontal 
lobe which is somewhat triang-ular with the base backward 
and apex forward. Behind, and prolong-ed downward to fit 
in the middle fossa, is the temporo-sphenoidal lobe, and, behind 
this, the occipital, also triang-ular with its base forward, flat- 
tened by pressure on the tentorium. The numerous appear- 
ances 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 
sing-leand occupy the mid-line. 

Beginning- on the mid-line in front and passing- backward, 
we find the following- appearances, viz : The g-reat long-itudinal 
fissure, with the rostrum of the corpus callosum seen at its 
bottom; the opticchiasm; the pituitary body, infundibulum and 
tuber cinerium leading- the one to the other; the posterior 
perforated space ; the transverse fibres of the pons ; the slig-ht 
median depression on the pons; the fissure between pons and 
medulla, and the anterior median fissure of the medulla. 

The appearances occurring- in pairs and described on one side 
only, are: The orbital face of the frontal lobe with its two sulci 

Des Anat— 26 



402 DESCRIPTIVE ANATOMY. 

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 beginninof 
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 albi- 
ans; and, from this point backward, the roots of the cranial 
nerves. 

The long'itudinal fissure and the corpus callosum are else- 
where 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 hypo- 
physis cerebri, is situated in the sella Trucica, 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, communicating with the third ventricle through 
the infundibulum. The infundibuluin is a small tube of grey 
matter attached above to the lamina cineria and below to the 
infundibulum. It always communicates with the third ventri- 
cle. The laviina cineria, or tuber cinerium, is a small mass 
of g"rey 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 carpora albicantia. 

^yx^s^ posterior perforated space is in the triang-le formed by 
the crura on either side and the pons behind. It is made by 
a number of small vessels which here pass into the optic tha- 
lami. The remaining- appearances require no further descrip- 
tion. 

The olfactory bulb (usually 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 S34vius 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 



THE CENTRAL NERVOUS SYSTEM. 403 

nerve; internally, by the optic chiasm, 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 optic tract will be described with the cranial 
nerves. The cms cerabri is a round cord which serves to 
connect the pons with the cerebrum. It is about three fourths 
of an inch in leng-th and is composed of two sets of long-itudi- 
nal white fibres, superficial and deep (or anterior and poste- 
rior; and an intermediate bundle of gray matter called locus 
)iigcr. 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 lono-itudinal 
fibres, or tegmentum, pass from the olivar}^ 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 inter-peduncular space. 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 
alljicantia or niamilluria 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 reversing their course which forms the 
corpora albicantia. This space contains the pituitary body, 
infundibulum, lamina, or tuber, cinerium, corpora albicantia, 
or mamillaria, 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 



404 DESCRIPTIVE ANATOMY. 

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 majus. 

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 
backw^ard along the middle line, called the raphe; bordering 
each side of the raphe is a slight ridge produced by a bundle 
of longitudinal fibres, the two ridges being- called the nerves 
of Lancisi. E^xternal to these are seen a few other longitudi- 
nal fibres, producing slight ridges which are called the lateral 
longitudinal strise. When the corpus callosum is bisected 
longitudinally it is seen to be about four inches long and to 
bend vertically downw^ard both in front and behind. The 
bent, rounded, posterior extremity is called the splenium, or 
pad, or bulb, the central portion 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 called peduncles, which 
pass downward and backward to the base of the brain to 
terminate at the anterior perforated space. Contained in the 
substance of the brain, between its base and the corpus callo- 
sum, 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 ventricular 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 ventri- 
cles, and third and fourth ventricles, these cavities all com- 
municating with one another by means of small foramina. 



THE CENTRAL NERVOUS SYSTEM. 405 

The g-eneral ventricular 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 oblong-ata below. The lateral 
ventricles exist in the two hemispheres of the cerebrum, sepa- 
rated from one another 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, occupy- 
ing- a position on the medulla and the pons. 

The Lateral Ventricles. 

The rig-ht 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 re- 
moval, the floor, formed of various objects, is brougfht into view. 
Bach 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 cor- 
pus callosum, and in part by the frontal, parietal, occipital, 
and tempero-sphenoidal lobes. The inner zuall is formed in 
part by a portion of brain tissue called the Seftiun Liicidum 
(L. Transparent Septum). The outer zuall is the point of 
junction of the corpus callosum with the fibresof the cerebrum, 
while the floor is composed of a larg-e 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 cerebrum. The floor 
from before backward is made up of the corpus striatum, the 
tenia semicircularis, or horny bind of Tarinus, the optic 
thalamus, the choroid plexus, and the fornix. E)ach of 
these requires a separate description. 

The Corpus Slriatinn{\^. .S7m///^6-,g-rooved or furrowed) is an 
oblong-, or pear-shaped, g-ravish mass, with its larg-e end in 
front. It is divided into two portions, called the ititra- and 



406 DESCRIPTIVE ANATOMY. 

extra- ventricular -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 inte7-nal capsule. External 
to this comes the extra- ventricular portion, the nucleus lenticu- 
laris (Iv. lense-shaped) ; and on the outer face of this ag-ain is a 
mass of white matter, called iho, etxer7ial capsule. The white 
matter which descends 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 oblong-ata, and throug-h that to the spinal cord. 

The Tenia Semicircularis is a rounded cord, which lies in 
the groove between the corpus striatum and the optic thalamus • 
It may be traced into the descending- horn of the lateral ventri- 
cle, where it joins with the anterior pillar of the fornix ; and 
thence backward into the roof of the descending* horn, where 
it terminates in a projection of gray matter, the Corpus 
Amyg-dalce. 

The Optic Thalamus \% amass of gray matter which projects 
into the floor of the body of the lateral ventricle, and forms the 
lateral walls of the third ventricle. It will be described in 
connection with that ventricle. 

The Fornix (L. Fornix, an arch, or vault) is a long"itudinal 
band of white matter lying- beneath the corpus callosum; and 
blended with its fellow of the opposite side behind, but separate 
in front. Behind it thins out into a broad, flattened band, the 
outer edg-e of which is called the corpus fimbriatum (L. Fim- 
bria., an edg-e, or border). It descends into the floor of the 
descending- horn, covering- the projection in that space known 
as the hippocampus major. Between the two posterior pillars 
of the fornix transverse fibres are stretched, which from their 
supposed resemblance to a harp have g-iven the name of lyra to 
this portion of the fornix. These posterior fibres blend with 
the white matter forming- the hippocampus major. Anteriorly 
the two pillars descend to the base of the brain, not connected 
by transverse fibres, and pass downward to the corpora 
mamillaria, where they reverse their course and turn upward, 



THE CENTRAL NERVOUS SYSTEM. 407 

to be lost in the optic thalamus of the corresponding" side. 
The anterior pillars of the fornix are connected with the pe- 
duncles of the pineal g-latid, and receive fibres from the septum 
lucidum. 

The Choroid Plexus passes along- the edg"e of the most in- 
ternal object in the ventricle, the fornix. It is a mass of blood 
vessels arrang-ed 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 throug-h the body of the ventricle, and continue their 
course into the descending horn, at the bottom of which other 
small vessels unite with them. The choroid plexus of each 
side passes beneath the bod}- of the fornix, unites with the 
choroid plexus of the opposite side, and forms the true roof of 
the third ventricle. Prom 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 matral covering of 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 
cockspur, extends backward into the occipital lobe ; and pre- 
sents 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 Descendin<r Horn pursues a tortuous course. It winds 
around the optic thalamus, passing first outward and back- 
ward, then downward and forward; and then, again changing 
its direction, it passes downward forward and inward, to ter- 
minate near the extremity of the temporo-sphenoidal lobe. 
This horn of the ventricle is found first in the parietal lobe; 
l)ut the major portion of it is in the temporo-sphenoidal lobe. 



408 DESCRIPTIVE ANATOMY. 

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 cor7iu ammonis , (L. a ram's horn), or hip-pocam-pus major, 
and terminates in the irregular projections, marked by inter- 
vening 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 dentate 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. 

It will be noticed that the descending horn of the lateral 
ventricle follows the course of the optic thalamus, and hence 
that that body forms the roof of the descending horn through- 
out 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 /?oor slopes from behind down- 
ward and forward ; and is made up of the structures which are 
included in the interpeduncular space. The lateral zvalls are 
formed by the optic thalami. Instead of a posterior wall there 
is an openeng, the acqueduct of Sylvius, or the iter a tertio ad 
qiiartum ventriculnm. The anterior voall is formed by a 
small bundle of gray matter, which is ciUed the anterior com- 
missure of the brain (L. committere, to join). This anterior 
commissure is found at the point where the two frontal lobes are 



THE CENTRAL XERVO'US SYSTEM. 409 

nearly in contact, and consists of an interchange of fibres be- 
tween the frontal lobes. It lies just in front of the anterior 
pillars of the fornix. Stretching- across from the optic thala- 
mus of one side to the same body of the opposite side is a second 
commissure, which is called the middle, or soft, commissure 
of tho. brain. This consists of the interchangfe of fibres be- 
tween the optic thalami, and is gfenerally broken in the removal 
of the brain. The posterior commissure, or third set of 
communicating" fibres found in the third ventricle, extends be- 
tween the posterior extremities of the two optic thalami, and 
consists of white fibres, the central one bsing- g"ray, these 
fibres forming- one of the boundaries of the acqueduct of 
Sylvius. Above the acqueduct of Sylvius is a small reddish- 
gray body, the Pineal Gland (L. Pinea, a pine cone), from 
which proceed two processes of g-ray matter, called the pedun- 
cles of the pineal g-land. These peduncles pass forward on 
the upper inner face of each optic thalamus to terminate by 
blending- with these bodies. The two unite behind in the com- 
missure of the peduncles of the pineal g-land. 

An examination of the third ventricle will show that there 
cirQ four openings communicating- with other cavities of the 
brain. Two are found upon its antero-lateral wall, the fora- 
mina of Munro ; one in its posterior wall, the acqueduct of 
Sylvius ; and the fourth in the floor, the Infundibulum. It 
will be remembered that at the base of the brain, occupying- 
the anterior portion of the interpeduncular space was seen the 
pituitary body, the infundibulum, the tuber cinereum, and the 
lamina cineria. Throug-h the last three pass the small open- 
ing- which leads from the floor of the third ventricle down- 
ward to the pituitary body. 

'Y\\^ foramina of Munro are bounded above and behind by 
the anterior pillars of the fornix, in front by the anterior com- 
missure. Throug-h these two opening-s the choroid plexus of 
the lateral ventricles descends into the third. They present a 
somewhat Y-shax)ed appearance, the tail of the Y being- repre- 
sented by the union of the choroid plexuses, while the two arms 
are represented by the foramina of Munro. Thus while the 
two lateral ventricles communicate with one another, the 



410 DESCRIPTIVE ANATOMY. 

communication 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 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 Acqiieduct of Sylvius, the opening- in the posterior 
wall, passes downward and backward, running- beneath the 
four projections of brain substance, called the corpora quad- 
rigeniina i^. fourfold bodies), and pisses 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 
intervention of the third and the foramina of Munro, the third 
in its turn communicating through the acqueduct of Sylvius 
with the fourth, and the fourth again by the foramen of 
Arantius communicating w^ith the ventricular cavity found in 
the spinal cord. 

The Fifth Ventricle. 

The Fifth Ventricle is described in the brain as consist- 
ing 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 ; 
but that the brain being developed from two separate centres, 
one on either side of the body, unites in the septum lucidum 
to form the division between the two lateral ventricles. The 
space between the two layers of which this septum is com- 
posed is spoken of as the fifth ventricle ; and it therefore bears 
no resemblance to the general ventricular cavity. 

'^\\Q fourth ventricle, rising behind the pons and the medulla 
will be described in connection with these portions of the brain. 

The Medulla Oblongata. 

Extending from the foramen magnum, or upper border of the 
atlas to the posterior border of the pons Varolii, is found the 
medulla oblongata, thus establishing connection between the 
spinal marrow and the brain. It is conical in shape, with the 
larger end above and forw^ard, and is about one and one-fourth 
inches in length. Passing down its centre in front is the ante- 



THE CENTRAL NERVOUS SYSTEM. 411 

rior median fissure, and similarly marking* it behind is the 
posterior median fissure ; these thoug-h not entirely bisecting- 
it, serve to indicate its division into lateral symmetrical halves. 
Kach half is subdivided into four portions by three long-itudi- 
nal g-rooves. Lying- beside the anterior median fissure, and 
separated by it from its fellow, is the portion called the corpus 
pyramidale ; just behind this, slig^htly more bulg-ing- and sepa- 
rated from it by a fissure, is a second portion called the corpus 
olivare, being- visible for about half an inch only. Behind 
this a third portion called the corpus restiforme, separated by 
a g-roove from the corpus olivare in front and by another 
slig-ht g-roove from the fourth portion, the posterior pyramid, 
wihch lies behind the corpus restiforme, beside the posterior 
median fissure by which it is separated from its fellow. The 
two posterior pyramids are small below, but as they are fol- 
lowed up they suddenly dilate into a bulbous enlarg-ement, 
and ag-ain as suddenly decreasing-, separate as they ascend and 
leave between them an ang-ular interval called the calamus 
scriptorius — writer's pen. When the medulla oblong-ata 
reaches the pons Varolii it seems, on superficial veiw, to stop 
short, but if the surface fibres of the pons, which are trans- 
verse in direction, are peeled off, it is seen that the pons, in 
its centre, consists of vertical, or long-itudinal fibres, which 
are continuous with the fibres of the medulla oblong-ata below, 
and, being- g-athered into two bands, emerge from its anterior 
border as the two crura cerebri. 

The Fourth Ventricle. 

The Fourth Ventricle is diamond-shaped, having- a superior 
and an inferior ang-le 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 



412 DESCRIPTIVE ANATOMY. 

acqueduct 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 
v^hich is called the superior medullary velum, or more fre- 
quently, the Valve of Vieusscns. 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 /foor is formed by the posterior 
surface of the poas, and the lower one-half by the posterior 
surface of the medulla oblongata. Along the mid-line is seen 
a fissure, the continuation of the posterior median fissure of 
the spinal cord. Opposite each of the lateral angles is found 
a depression, called th^ fovea anterior; and parallel with the 
median fissure are two rounded lobes of gray matter, called 
the fasciculi teretes. Near the central portion of the ventricle 
is sometimes seen a violet-colored streak, consisting of gray 
matter, lying just bsneath a thin covering of white (which 
gives the singular CDlor); and called the Toenia Violacea (L. 
Violet-colored band).. On the floor of this ventricle may be 
seen the origin of several of the cranial nerves. A few trans- 
verse fibres are seen extending across the ventricle, those 
above the origin of the eighth nerve called the Auditory Striai, 
and those below the Ivineae Transversae. 

Corpora Q,uadrigeniina. 

The Corpora ^uadrigeiiiina are situated above the acqueduct 
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, the posterior the testes. On the posterior 
extremity, or pulvinar, of the optic thalamus are found two 
minute projections, called the corpora geniculata, internal and 
external. From the nates there proceed two small white bands, 
which pass forward to join the internal geniculate body of 
either side , while from the testes two more prominent bands 
pass between the internal and external geniculate bodies. 
These rounded cords are known as the anterior and -posterior 



THE CENTRAL NERVOUS SYSTEM. 413 

brachia. From the testes two bundles of fibres proceed down 
ward, outward, and backward to join the cerebellum. These 
are the siipeyior -peduncles of the cerebellum^ or upper lateral 
boundaries of the fourth ventricle — processus e cerebello ad 
testes. 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 g-land to the optic thalami, 
while the other two have been noticed in the third ventricle as 
passing- forward alongf 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 
interpeduncular 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 oblonf>-ala, 
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 por- 
tion of it ; and presents for examination anterior and posterior 
surfaces, superior and inferior extremities. Many writers 



414 DESCRIPTIVE AXATOMY. 

describe it as having- lateral surfaces in addition to the 
anterior and posterior ; but as the lower portion of the med- 
ulla is almost completely circular, it is unnecessary to g-ive 
it more than two surfaces. 

The anterior surface, which looks downward as well as 
forward, rests upon the basilar process of the occipital bone ; 
while the posterior surface, a part of which is flattened and 
looks upward as well as backward, lies beneath the cerebellum. 

Just where the medulla joins the pons there is a deep con- 
striction, or g-roove, 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 nearU' to the arrangement of the 
cord itself, consequently we find pillars in the medulla corre- 
sponding- in a g-reat measure to the same pillars found in the 
cord. They are however, not so numerous, nor are they 
arranged in preciseU^ the same w^ay. 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 the direct continuation upw^ard of the anterior 
pyramid of the cord, but also receives fibres belonging to the 
crossed pyramidal tract 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 ex- 
tremity of the medulla, is an oblong projection, called the 
olivary body. This olivary body is concealed in the lower 
portion of the cord, where the fibres are deepl}^ seated and 
are covered b}" other portions of the medulla, and above it is 
made prominent h^ the divergence of the anterior pyramid and 
the fibres forming the restiform bod3^ Behind the olivary 
body is a large and prominent body, the restiform (Iv. Restis, 
a rope ; forma, shape) -which carries the direct cerebellar tract 
of the cord, and terminates by forming the inferior peduncles 
of the cerebellum. 



THE CENTRAL NERVOUS SYSTEM. 415 

Next to the rest'form body is the fourth and last portion of 
the medulla, \h.^ posterior pyramid, this portion of the medulla 
carrying- the fibres which in the cord are known as the columns 
of Goll and Burdach. The posterior pyramid, as it passes 
upward, blends with the restiform body; and the two pass to- 
ofether into the cerebellum to form its inferior peduncles. The 
anterior pyramids passing- throug-h the pons Varolii, enter into 
the formation of the crura cerebri. The olivar}- fibres disap- 
pear at the upper extremity- of the medulla, sinking- deeply into 
the pons, and probably aid in forming- the commissural fibres 
which exist betw^een the two lobes of the cerebellum as the 
superficial fibres of the pons. 

The appearances on the posterior face of the medulla have 
already been described in connection with the fourth ventricle 
of the brain. 

The Cerebellum. 

The Cerebellum, or Little Brai)i, is divided into two hemi- 
spheres by a deep fissure found on its inferior aspect and a 
projection found on the superior face. In the adult its relation 
in weig-ht to the cerebrum is variously stated as one to thirteen 
and one to twenty, Cruveilhier g-iving- 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", and the two lateral the "hemispheres". The hemi- 
spheres and the worm present a superior and an inferior 
surface. 

When viewed from above, the entire cerebellum seems 
undivided, the hemispheres being- directly continuous throug-h 
the middle of the worm. They slope from before downward, 
backward and outward. 

On the inferior surface the appearance is entirely different. 
Here a deep groove separates the two hemispheres; but the 
g-roove itself is partially filled by the lower aspect of the worm, 
which in its turn is subdivided by fissures into three portions. 
The g-rfjove in which the worm lies terminates anteriorly and 
posteriorly in notches, the incisura cercbelli, a)ilcrior and 
posterior. The anterior is the wider, and is not so deep as the 



416 DESCRIPTIVE ANATOMY. 

posterior. The worm extends into these notches, but does not 
completely fill them. The upper aspect of the worm is 
g-enerally called the superior vermiform process, and the 
lower the inferior vermiform process. Its sides are attached 
directly to the hemispheres of the cerebellum; and probably 
act as commissural fibres. On the upper face the worm has 
no subdivisions; but when viewed from below it is seen to be 
divided into a flattened mass of gray matter, the Posterior 
Medullary Velum, behind that a projection called the Uvula 
(L. Diminutive of Uva, a gfrape), and behind that the Pyramid. 

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 
appearance, the fissures, or sulci, beino- deep and narrow, 
while the laminae overlap one another throug-hout the entire 
area of each hemisphere. Certain of these sulci, however, are 
deeper and more distinctly marked than others, so that it 
becomes possible to divide the cerebellum into lobes which are 
less distinctly bounded than "the lobes of the cerebrum. 
There names are fanciful; and derived in the main from a sup- 
posed resemblance to other portions of the body. 

On the lozoer surface of each hemisphere, close to the 
median fissure, is a small projection of the cerebellum cut 
off by a deep fissure, called the Tonsils from their supposed 
resemblance to a gland in the throat. Beyond the tonsils, 
and cut off by the second inferior cerebellar fissure, is a 
curved lobe, which is called the Digastic. Next to this, and 
between the second and third cerebellar sulci, is a long 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 slendar lobe, and 
occupying-the posterior extremity of the cerebellum, is another 
long and slender lobe, which borders the slender lobe, extendinof 
from the posterior extremity of the median fissure around to 
the front of the flocculus. This is known as the -postero- 
infer'ior Lobe. 



THE CENTRAL NERVOUS SYSTEM. 417 

On the upper surface the lobes are very indistinct, and can 
scarcely be described as separate lobes. There are really but 
two lobes on the superior surface, the f>ostero- superior and 
the anterior, or square, lobe. It will be noticed that the infe- 
rior 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 Spinal Cord. 

The Sphial Cord is the great connecting link between the 
brain and the various members of the body. It seems to 
correspond partially to a mass of insulated wires, a large por- 
tion of its work being the transmission of impulses to and 
from the brain ; but it contains nerve centres which in them- 
selves originate impulses, hence it is not merely a bundle of 
transmitting fibres. It is markedly similar to the brain in 
the arrangement of its membranes, and to some extent in its 
functions ; but is dissimilar in the arrangement of the mass of 
gray and white matter. 

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. 

The Dura Mater of the spinal cord is, hov^^ever, unlike that 
of the brain, much too large for the cord which it envelopes. 
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. 

The Arachnoid, forms here, as in the brain, a serous mem- 
brane, covers the entire surface of the cord, and lines the inner 
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 

Des Anat— 27 



418 DESCRIPTIVE ANATOMY. 

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. 

The Pia Mater covers the cord nearly as it does the brain, 
but with some slig-ht differences. It sends prolong-atious to 
accompany the nerves which leave the spinal cord, it conveys 
the blood-vessels as in the brain; but it also gives lig-amentous 
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 wedg-e extends outward to blend 
with the dura. These prolong-ations form the Ligamentum 
Denticulatum, and serve the purpose of retaining- the cord 
steadily in position, and of preventing its movement in the 
large chamber furnished for it by the dura. 

The Cor^ itself is nearly, though not quite, cylindrical, be- 
ing slightly flattened in the antero-posterior direction. It is 
seventeen 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 tw^o-thirds of the spinal 
canal in the adult, though it is longer comparatively in the 
foetus, extending here to the bottom of the sacral canal ; but 
apparently the vertetwae grow more rapidly than the cord and 
hence the cord is carried upward in the canal until it reaches 
about the level of the second or third lumbar vertebra. The 
cord presents an enlargement in the cervical region, where 
the branches are given off which supply the upper extremity ; 
and a similar enlargement in the lower lumbar region, where 
'he branches are given off which supply the lower extremity. 
Of course, in the living being, its curvature corresponds 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 

Posterior. 

z' The anterior is very wide, but shallow; w^hile the, ^posterior 

s very deep and narrow. In addition to these two fissures. 



THE CENTRAL NERVOUS SYSTEM. 419 

the spinal nerves, rising- by two bundles of roots, called the 
anterior and posterior, make an incomplete and irreg-ular fissure, 
which extends throug-h the length of the cord, and serves 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 
pathalog-ical than by anatomical examination. 

It will be seen that the cord, unlike the brain, is arranged 
with all of its g'ray matter in the centre, and the white matter 
surrounding it; and on section oE the cord in living- animals 
deg-eneration takes place in two directions. Those fibres which 
convey impulses to the brain deg-enerate upward, while those 
which convey impulses from the brain deg-enerate 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 fis- 
sures, 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 trans- 
mission from the cord to the brain. Commencing at the ante- 
rior median fissure the first tract is called the Anterior Pyramid ., 
or Anterior Pyramidal Tract, ■a.nA next to this is found the 
Anterior Ground Zone, or Anterior Root Zone, being that 
portion of the cord in front of the anterior roots of the spinal 



420 DESCRIPTIVE ANATOMY. 

nerves. Then comes behind the spinal nerves a second ground 
zone, which is, however, called the Lateral bujidle, and external 
to both of these and superficial to them is the Antero-lateral 
tract, v^^hich conveys both ascending- and descending fibres to 
the cerebrum. Behind this tract, also on the superficial sur- 
face of the cord, is the Direct Cerebellar tract which extends 
as far as the posterior root zone; and between the direct cere- 
bellar and the gray matter in the interior of the cord is the 
Crossed Pyramidal Tract. Behind the posterior root zone 
are tw^o tracts, the one next to the roots of the nerves being 
Burdacli 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 GoU and the column of Bur- 
dach unite to form iho. ^posterior column of the 'medulla^ or, as 
it is frequently called, funiculus cuneatus (Iv. Dim. of funis, 
a cord ; cuneatus, wedge-shaped) ; that the direct cerebellar 
tract passes into the restiform body ; that the crossed pyram- 
idal 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 pos- 
terior 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 ante- 
rior horns are bluntly pointed. These masses of gray matter 
contain the fibres furnishing the various centres in the spinal 
cord. 

It will of course be seen that the branches which proceed 
from the spinal cord are collectively enormously larger than 



THE CENTRAL NERVOUS SYSTEM. 421 

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 spi- 
nal canal through the intervertebral foramina, and are distrib- 
uted 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 sensory functions, the spinal nerves are composed 
of bundles, performing 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, Lum- 
bar, and Sacral. Interposed between the brachial and the 
the lumbar are a set of spinal nerves, the Dorsal, which do 
not unite to form plexuses, but are distributed individually 



422 DESCRIPTIVE ANATOMY. 

like the cranial nerves. Some writers mention a coccygfeal 
set ; but these in reality belong- to the sacral plexus. 

E)ach spinal nerve as itemerg-es 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 interver- 
tebral foramen. From this point it becomes continuous with 
the ordinary 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 emerg^ence an 
enlargement; and as every nerve arises by an anterior and a 
posterior root, this enlargement, or ganglion, is confined to one 
of these roots. 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 degenera- 
tion downward 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 
cannot be demonstrated anatomically. 

E^ach spinal nerve immediately after it emerges from the 
spinal canal divides into an anterior and a posterior branch. 
The posterior branches are small in size and comparatively 
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 plexus is formed by the intercommunication of the ante- 



THE CENTRAL NERVOUS SYSTEM. 423 

rior 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 integfument 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 forming- what is known as the 
Great Occipital Nerve {^Occipitalis Major), 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 g-iving- oif its 
posterior branch, sends a communication 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 formation of the brachial plexus. Prom this loosely 
formed cervical plexus branches are g-iven off which are dis- 
tributed 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 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 Snperfi- 
cialis Colli, Auricularis Mag'nus, and Occipitalis Minor. 

Superficial Branches. 

Superficialis Colli Auricularis Mag-nus Occipitalis Minor 
The Superficialis Colli. 

The Superficialis Colli, the first branch, is the product of 
the sccotzd and third cervical nerves ; and like all the superfi- 
cial branches from this plexus, it winds around the posterior 
border of the sterno-cleido-mastoid muscle, about at its middle, 
and becomes superficial in that situation. It then passes up- 
ward and forward, crosses the sterno-cleido-mastoid, runs to 
the lower border of the inferior maxilla, 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 face. 



424 DESCRIPTIVE ANATOMY. 



The Auricularis Magnus. 

The Auricularis Magnus is the product of the second and 
third cervical nerves. After emerg-ing- from the posterior bor- 
der of the sterno-cleido-mastoid, it crosses that muscle, and 
divides into two branches, mastoid and auricular. 

The mastoid branch ascends to the mastoid process of the 
temporal bone and is distributed to the skin in that reg"ion after 
communicating" with the seventh nerve. 

The auricular branch divides into several twig^s, which are 
distributed to the skin on the back of the pinna. 

The 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 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 larg-est, 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. 

The Descending Superficial Branches. 

The unnamed Descending- Superficial Branches are produced 
by the third -dM^^ fourth cervical nerves. They emerg-e from 
beneath the sterno-cleido-mastoid muscle, like the preceding 
branches, about opposite the middle of its posterior border- 
They are irregular in size and number. One set passes down- 
ward and inward toward the mid-line of the body, crossing 
the clavicle near its inner extremity and ending in the integu- 
ment 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 integ-ument covering the 
pectoral muscles, while the third set, called sometimes the 
acromial, or deltoid, passes outzvard, and is distributed to the 
skin in the neig-hborhood of the shoulder. 



THE CENTRAL NERVOUS SYSTEM. 425 



Deep Branches. 

Muscular Phrenic 

Communicans Noni 

The Muscular Branches. 

The muscular branches are distributed to all of the muscles 
of the front of the neck with the exception of the depressors 
of the hyoid bone. They consist of a branch to the sterno- 
cleido-mastoid muscle, which arises from the second cervical 
and communicates with the eleventh cranial in the substance 
of the sterno-raastoid muscle ; a branch to the scalenus medius, 
coming- from the third ^nA fourth nerves ; one to the levator 
anguli scapulas ; 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 rec- 
tus capitis anticus minor, and the long-us colli. 

The Communicans Noni. 

The most important communicating branch is the Commu- 
nicans Noni. This nerve is the product of the second and 
third cervical nerves. It passes downward, forward, and 
inward, and unites with the descending- branch of the hypo- 
g-lossal 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 
depressors of the hyoid bone, with the exception of the thyro- 
hyoid, which is supplied by a branch from the hypog-lossal 

nerve itself. 

The Phrenic. 

The last and most important branch of the plexus is the 
l^hrenic Nerve. It is formed by contributions from the third 
and fourth cervical nerves, reinforced by a small filament from 
the fifth. The course of the nerve on the two sides of the 
hody differs. 



426 DESCRIPTIVE ANATOMY. 

On the rig-ht 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, thoug-h occasionally it remains on the scalenus 
anticus 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 dia- 
phragm, and is distributed to that muscle from its under 
surface. 

The left nerve, formed in the same way, passes on the scalenus 
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. Then 
it crosses the end of the transverse aorta, passes downward on 
the left side of the pericardium, lying next to the left pleura, 
and then, like its fellow of the opposite side, enters the dia- 
phragm 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 lozuer cervical nerves and 
a portion of the first dorsal nerve. The manner of its forma- 
tion differs indifferent individuals; but it is usually formed ia 
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 cersiical 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 



THE CENTRAL NERVOUS SYSTEM. 427 

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. 

The plexus is triang-ular in outline, with its base directed to- 
wards the spinal column and its apex extending- downw^ard. back- 
ward and outward towards the axillary space. It passes between 
the scaleni muscles ; and comes into relationship with the sub- 
clavian 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 forward 
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 lying behind the axillary artery. Just at the 
termination of the second portion the inner and the outer cord 
each give 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 downward 
and inward to the lower part of the third intercostal space, it 
will be seen that the axillary artery is completely surrounded 
by the cords of the plexns. 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 np into their terminal 
h) ranches. 

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 oflf way-side 
branches, some muscular and some cutaneous, which are dis- 



428 



DESCRIPTIVE AX ATOMY 



tributed to the lateral aspect of the chest, as well as to the 
muscles of the scapular group and the skin covering* them. 



Wayside Branches. 



Above the 
Clavicle 



f Suprascapular 
Rhomboid 
Posterior Tho- 
racic 
Communicating- 
Subclavian 
Scaleni 
lyong-us Colli 



Below the 

Clavicle 



Anterior Tho- 
racic, internal. 

Anterior Tho- 
racic, external. 

SubscaDular 



The Suprascapular. 

The Siiprasca^idar hrancJi is derived from the fifth and 
sixth cervical nerves. It passes downward and outward par- 
allel with the posterior belly of the omo-hyoid muscle. Reach- 
ing" the upper border of the scapular it passes throug-h the 
suprascapular notch beneath the transverse lig-ament. and 
consequently below the corresponding- artery, enters the 
supraspinatus 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. 

The Rhomboid. 

The branch to the Rhomboideus is a product of the nftli 
cervical nerve. It passes throug-h the fibres of the scalenus 
medius, and is then distributed to the rhomboid muscle, or 
muscles. 

The 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 axillar\^ and is distributed to the serratus mag-nus 
muscle. 

Communicating. 

The communication with the cervicle plexus is by means of 
the fifth cervical, which joins with the phrenic nerve. 



THE CENTRAL NERVOUS SYSTEM. 429 

The Subclavian. 

The nerve to the Subclaviiis jiiuscle 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. 

The Branches g-iven below the clavicle, besides the terminal 
ones, are the external and internal anterior thoracic and the 
subscapular nerves. 

The External Anterior Thoracic. 

The Exteriial Anterior Thoracic, derived from the outer 
cord of the plexus, is distributed to the pectoralis major muscle. 

The 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 re- 
ceiving- a communication from the external anterior thoracic, 
is distributed to the pectoralis major. /or^ 

The Subscapular. 

The Subscapular nerves are three in number ; and the}'' are 
derived from the posterior cord. They are known as the 
upper, middle, and lower. The upper is distributed to the 
subscapularis muscle alone, the middle accompanies the sub- 
scapular artery, and terminates near the latissimus dorsi ; 
while the /oz.'cr is distributed to the teres major, furnishing" 
some twig-s to the subscapularis. 

Terminal Branches. 

Musculo-cutaneous Internal Cutaneous 

Median Lesser Internal Cutaneous 

Ulnar Musculo-Spiral 

Circumflex 

The terminal branches of the Brachial Plexus orig-inate from 
the cords of the plexus as follows : The internal cord produces 
the internal cutaneous, the lesser internal cutaneous, the ulnar, 



430 DESCRIPTIVE ANATOMY. 

and one head of the median. The externcd cord divides into 
two branches : one forms the outer head of the median, while 
the other is the musculo-cutaneous. The -posterior cord di- 
vides into the circumflex and the musculo-spiral. 

The division of the plexus takes place on the beg-inniag- of the 
third portion of the axillary artery, which is here completely 
surrounded by the cords of the plexus; but immediatelvaf ter 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 cuta- 
neous and ulnar nerves to the inner side, musculo-spiral be- 
hind, 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. 

The 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. E^merging 
from the coraco-brachialis, it passes between the brachialis 
anticus and the biceps, runs into the interval between the brachi- 
alis anticus and the supinator longus, where it becomes superfi- 
cial 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 on 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 nerve in its course gives off muscular branches to the 
coraco-brachialis, the biceps, and the inner portion of the 
brachialis anticus. 



THE CENTRAL NERVOUS SYSTEM. 431 



The Internal Cutaneous. 

The Internal Cutaneous Nerve is the product of the inner 
cord of the plexus ; and is probably derived from the eiofhth 
cervical and first dorsal. It is an internal relation of the third 
portion of the axillary arter}^ to the termination of that vessel ; 
and then becomes an antero-internal relation to the brachial 
artery, lying- in close companionship to the basilic vein. 
At the middle of the brachial artery the nerve, with the basi- 
lic vein, pierces the investing- fascia ; and still remaining* an 
antero-internal relation of the brachial artery to its termina- 
tion, is, for its lower half, separated from that vessel by the 
deep fascia of the forearm. 

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 down- 
ward, being divided into an anterior and a posterior set. the 
anterior supplying the integ-ument of the inner front aspect of 
the forearm as far as the wrist, while the ^o^/'t'r/or supply the 
integument on the postero-internal aspect of the forearm down 
to the wrist. 

The Lesser Internal Cutaneous. 

The Lesser Inter)ial Cutaneous^ or Nerve of Wrisberg, aris- 
ing from the internal cord, receives its branches from the 
eighth cervical and first dorsal. It is very irregular in its 
origin, and ma}' be the product of the lateral cutaneous branch 
of the second intercostal nerve ; but, as a rule, it simply re- 
ceives a communication from that nerve. At first it is an 
internal relation 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 
thj postero-internal aspect of the arm, and near the elbow 
turns backward to be distributed to the integ-ument on the 
1 jwer third of the arm and in the neig-hborhood of the olecra- 
non process. 



432 DESCRIPTIVE ANATOMY. 

The Ulnar. 

The Ulnar Nerve is the last branch of the internal cord of 
tHe plexus; and like the preceding- branches, contains fibres 
from the eigfhth cervicle 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 ulnar, forming'^^ 
what is g-enerally 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 profundus 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 liga- 
ment, 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 an- 
terior 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 
condyle 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 ulnar artery to 
its outer side for the lower two-thirds of its course. 

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 digfi- 
torum. About three inches above the wrist joint it g-ives off a 



THE CENTRAL NERVOUS SYSTEM. 433 

cutaneous branch, the dorsal cutaneous branch of the Ulnar, 
which will be described later ; and then a superficial branch 
which enters the palm of the hand. A few small twig's are 
given olT to the elbow joint. 

Superficial Branch. After entering- the palm, the super- 
ficial branch supplies the palmaris brevis, and the skin cover- 
ing the hypothenar eminence, a twig to the inner side of the 
little finger, and a branch which bifurcates to supply the ad- 
jacent sides of the little and ring fingers, and lastly a commu- 
nicating 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 sup- 
plies the little finger and the inner side of the ring finger. 

Deep Branch. The Deep Branch of the Ulnar passes be- 
tween the flexor minimi digiti and the abductor minimi digiti, 
runs along the palm of the hand accompanying the deep palmar 
arch, supplies the two inner lumbrical muscles, the two outer 
interosseous muscles, the muscles of the hypothenar eminence, 
with the exception of the palmaris brevis, and in the thenar 
group, supplies one muscle and a half, viz., the adductor poUi- 
cis, and the deep head of the flexor brevis pollicis, the remaining 
portion of the hand being supplied by the median nerve. 

The Dorsal Ciilancoiis 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 ulnar 
to the back of the hand. Here it divides into cutaneous 
branches, the most internal 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 /jranch communicates with a branch from the 
radial nerve, passes to the cleft between the ring and middle 

Des Anat— 28 



434 DESCRIPTIVE ANATOMY. 

fing"ers, and divides to supply the adjacent sides of these two 
fing-ers. These dorsal collateral digfital branches communicate 
in the matrix of the nail with the palmar branches already 
noticed. 

The 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 maintains that relation to the termination of that 
vessel, a fing-er's breadth below the middle of the front of the 
elbow joint. It should here be noted that in cases of hig-h 
bifurcation of the brachial, the median nerve almost invariably 
passes between the two branches, the branch in front usually 
corresponding- to the radial artery, and the branch 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 
drawn from the inner to the outer condyle of the humerus, th 
external boundary being- the supinator long-us and the innei 
boundary the pronator radii teres. The nerve exactly bisects 
this space, passes between the two heads of the pronator radi' 
teres muscle, the deep head of which alone separates it from 
the ulnar artery. Crossing- over the ulnar artery, and sep- 
arated from it by the deep head of this muscle, it then passes 
down the middle of the front of the forearm, covered by the 



THE CENTRAL NERVOUS SYSTEM. 435 

superficial head of the pronator radii teres and overlapped by 
the flexor carpi radialis on its outer side and the flexor sublimis 
dig"itorura on its inner side, and lying- nearly directly behind 
the palmaris long-us. It then passes to the front of the wrist 
joint, crosses beneath the anterior annular lig-ament into the 
palm of the hand, and breaks up into its terminal branches. 

Like the ulnar nerve it g-ives 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 g*ives off a large branch, called 
the anterior interosseous. 

The Anterior Interosseous Nerve arises opposite the bicipi- 
tal tubercle of the radius, runs downward on the interosseous 
membrane, 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. 

Immediately below the elbow joint the median gives off 
branches to all of the muscles on the front of the forearm with 
the exception of the flexor carpi ulnaris and the inner half of 
the flexor profundus digitorum. In other words, it supplies 
muscular twig-s to six and one-half out of eig-ht of the muscles 
of the forearm ; viz., the pronator radii teres, flexor carpi radi- 
alis, palmaris long-us, flexor sublimis digitorum, flexor long-us 
pollicis, pronator quadratus, and outer one-half of the flexor 
profundus digitorum. 

Just before reaching- the anterior annular ligament it gives 
off cutaneous branches, which are distributed to the integument 
covering- the thenar eminence of muscles, and which commu- 
nicate with the superficial branch of the ulnar nerve, distrib- 
uted 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 anterior annular lig-ament, the remaining- muscles of the 
group being supplied by the ulnar nerve. The other set 



436 DESCRIPTIVE ANATOMY. 

divides into palmar collateral branches, of which thejii'st tvjo 
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, w^hich will be described 
later. The third hi'anch passes to the radial side of the index 
finger ; Va'^ fourth to the cleft between the index and middle 
fingers : and the fifths after receiving a communication from 
the ulnar, passes to the cleft between the middle and ring 
fingers, and supplies the adjacent sides of those fingers, all 
of these branches communicating with one another and also 
with the dorsal nerves. 

The Musculo-Spiral. 

The Musculo- S;piral,ih.& largest branch of the brachial plexus, 
arises from the posterior cord ; and is said by some authorities 
to get fibres from all of the cords of the brachial plexus, 
though others deny that it receives any from the fifth cervical 
nerve. It passes downward as a posterior relation of the third 
portion of the axillary artery. At the termination of that 
vessel it passes between the internal head of the triceps muscle 
and the shaft of the humerus ; and at the junction of the 
lower third with the upper two thirds of the shaft of the 
humerus, pierces the external intermuscular septum, and 
appears opposite the interval between the brachialis anticus 
and the supinator longus. At the elbow joint, while still ly- 
ing between these two muscles, it divides into its two terminal 
branches, the radial and the ^posterior iyiterosseus. Before 
its division it gives off both cutaneous aud muscular branches. 

Branches of the Musculo-Spiral. 



Way- 
Side 



( Internal | Radial 

Cutaneous K Upper Kxternal Terminal ■( Posterior 

( Lower E^xternal ( Interosse 
Muscular 

The Internal Cutaneous B7'anch is distributed to the skin 
covering the middle of the back of the arm ; and extends 
as far as the distribution of the nerve of Wrisberg, with which 
it communicates. 

The Upper External Cutaneous pierces the external inter- 



THE CENTRAL NERVOUS SYSTEM. 437 

muscular septum ; and is distributed to the skin covering" the 
outer portion of the biceps muscle. 

The Lo'.ver External Cutaneous Branch pierces the exter- 
nal intermuscular septum ; and is distributed to the skin cov- 
ering- 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 
continuation of the triceps, to the brachialis anticus, supinator 
longus, and extensor carpi radialis long-ior, that is, to all of 
the muscles which take their orig-in above the external con- 
dyle of the humerus. 

The Radial. 

Of the two terminal branches of the median, the Radial is 
purely a nerve of common sensation. It commences in the 
interval between the supinator long-us, externally, and the 
brachialis 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 re- 
lation 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. Emerg-ing from beneath this tendon, 
it becomes superficial, g-ives 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 fingfer, a third, 
which divides to supply the adjacent sides of the middle and 
index fing-ers, and a fourth, which after receiving a communi- 
cation from the dorsal cutaneous branch of the ulnar, divides 
to supply the adjacent sides of the middle and ring fingers. 

The Posterior Interosseous. 

The Posterior hiterosseous Nerve, the second terminal 
branch of the musculo-spiral, commencing while the latter 
nerve lies between the supinator longus and brachialis anticus, 
passes across the elbow joint to the supinator brevis muscle, 
and runs directly through the substance of that muscle. It 
passes through the supinator brevis to the back of the 



438 DESCRIPTIVE ANATOMY. 

forearm ; and runs downward on the posterior face of the 
interosseous membrane to reach the back of the wrist, where 
it has a small g-ang-liform 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 long-ior. The muscles 
supplied are the extensor carpi radialis brevior, the supinator 
brevis, the extensor communis dig-itorum, the extensor minimi 
digiti, the extensor carpi ulnaris, the extensor ossis metacarpi 
pollicis, the extensor primi internodi pollicis, extensor secundi 
internodi 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 inter- 
osseous nerve ;" and the radial should be described as a way- 
side branch of the nerve, as it really is. The above description 
is g-iven in conformity with custom. 

The Circumflex Nerve. 

The Circumflex Nerve is the last of the terminal branches 
of the Brachial plexus. Arising- from the posterior cord, in 
common with the musculo-spiral, it passes downward 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- throug-h 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 accompany the 
posterior circumflex vessels, winding- around the surg-ical 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. 



THE CENTRAL NERVOUS SXSTEM. 439 

Dorsal Spinal Nerves. 

The dorsal spinal nerves are izuelve pairs, the posterior 
branches of which are distributed to the structures of the back, 
while the anterior cords form the intercostal nerves, and, un- 
like other spinal nerves, do not form a plexus but are distrib- 
uted separately. 

The 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 bra- 
chial plexus, and the tzcelfth 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 
integ-umenton the front and sides of the thorax and abdomen. 
Each intercostal nerve runs forward in the intercostal space 
between the intercostal muscles to near the edg-e of the sternum 
where it turns forward and becomes superficial, being- called 
the anterior cutaneous. It is then distributed to the integ-ument 
of the front of the chest and abdomen, most of the filaments 
passing- outward in a recurrent course. The six upper nerves 
appear as the anterior cutaneous throug-h 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 extremities of the intercostal 
spaces these last nerves pass on between the broad muscles of 
the abdomen, and the last one, thoug-h 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 g-ives off a branch called lateral cutaneous y 
which divides into two, one branch passing- forward and the 
other backward, both being- distributed to the integ-ument on 
the side of the chest or abdomen. The first intercostal nervCy 
owing- to the fact that most of the cords from which it is de-' 
rived g-o to the brachial plexus, gives off no lateral branch, 
and, to compensate for this delinquency, the lateral cutaneous 
branch of the second nerve is remarkably larg-e, and not only 
fulfils the office of the lateral cutaneous branches for itself 



440 DESCRIPIVE ANATOMY. 

and the first, but under the name of intercosto-humeral , passes 
into the axilla, where it communicates 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 
integ-ument of the gluteal region. 

The 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 Lumbar Plexus. 

The manner of formation of the Lumbar Plexus is g-enerally 
as follows: The tzuel/th (for^a/ ^zeri'e 'g-ives a branch which 
descends in the substance of the psoas mag-nus muscle to unite 
with the fi7'st lumbar. The cord thus formed g-ives off the 
ilio-hypog^astric and ilio-lumbar nerves, and a branch which 
descends to unite with the second lumbar. The second lum bar, 
after receiving- this branch, g-ives off a branch of distribution, 
the g-enito-crural, and a communicating- branch, which descends 
to unite with the third lumbar, so that the g-enito-crural is the 
product of the first and second lumbar. The cord formed by 
the union of the branch from the second and third lumbar 
nerves g-ives off an external cutaneous branch and a branch 
which unites with the fourtli 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 remain- 
ing- 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 
mag-nus muscle ; and its branches, with the exception of the 
g-enito-crural, pass outward beneath the posterior surface of 
that muscle, the g-enito-crural perforating- the muscle and 
appearing- upon its anterior surface. 



THE CENTRAL NERVOUS SYSTEM. 441 

Branches of the Lumbar Plexus. 

Ilio-Hypog-astric Ilio-Ing-uinal 

External Cutaneous Genito- Crural 

Anterior Crural Obturator 

Muscular Communicating- 

The Branches of the Lumbar plexus, named in the order in 
which they arise from above downward are the ilio-hypog"astric, 
ilio ing-uinal, external cutaneous, g-enito-crural, anterior crural, 
and obturator. Some authorities mention the accessory obtu- 
rator, which is an infrequent branch. In addition to these the 
plexus also gives muscular branches, which supply the psoas 
magfnusandquadratus lumborum muscles, and arise irregularly 
from the plexus. 

Ilio-Hypogastric. 

The Ilio-Hypog-astric, 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 and 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 brancli, piercing- successively the internal and ex- 
ternal oblique muscles, passes downward on the thigh toward 
the trochanter major, to be distributed to the integument 
behind the lateral cutaneous branch of the last dorsal nerve. 

The hypogastric branch continues the direction of the main 
trunk, at first lying between the internal oblique and the 
transversalis, and then between the internal and external 
oblique muscles, finally piercing the aponeurosis of the exter- 
nal 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 
common with the ilio-hypogastric, and passes downward and 
outward, parallel with and below that nerve, across the quad- 
ratus lumborum muscle. After crossing the iliacus internus, 
it pierces the transversalis muscle ; and between that muscle 



442 DESCRIPTIVE ANATOMY. 

and the internal oblique, communicates with the hypog-astric 
branch of the ilio-hypog-astric. It then becomes more super- 
ficial near the superficial abdominal ring-, and leaving- the 
abdominal cavity throug-h that aperture, passes to the thigh, 
where it is distributed to the skin covering- the inner, upper 
front aspect of the thig-h, and to the scrotum in the male and 
to the labium in the female. 

Genito- Crural. 

The Genito- Crural is the product of the first and second 
lumbar nerves. It passes first directly forward throug-h the 
fibres of the psoas magnus muscle, and descends upon that 
muscle to just above Poupart's lig-ament, where it divides into 
a g-enital and a crural branch. 

The g-enital 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 thig-h, to be distributed to the integ-ument of 
its inner front aspect as far as the middle. It is an anterior 
relation of the femoral artery. 

The External Cutaneous. 

The External Cutaneous Nerve is the product of the second 
and third Lumbar nerve. It passes downward and outward 
across the iliacus internus muscle behind the peritoneum, and 
reaches the notch found below the anterior superior spinous 
process 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 thig-h, its distribution lying- in the interval between the 
iliac branch of the ilio-ing-uinal and the middle cutaneous branch 
of the anterior crural. Fibres from this nerve descend as far 
as the knee joint. 



THE CENTRAL NERVOUS SYSTEM. 443 

The Obturator. 

The Ohtiirator 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 pecti- 
neus, and has a cutaneous branch which passes to the skin of 
the inner side of the thigh. The posterior branch also drops 
a twng to the hip joint, and supplies the obturator externus 
and adductor magnus muscles. 

The Anterior Crural. 

The Anterior Crural 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 be- 
tween 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 suferficial, or cutq,neoiis, 
branches, and deep^ or muscular branches. 
Superficial Branches. 
Middle Cutaneous Internal Saphenous 

Internal Cutaneous 
The Middle Cutaneous. 

The Middle Ciitaneoiis Jjranch passes forward superficial to 
the femoral artery ; and is distributed to the integument which 
covers the front of the thigh, lying between the internal cuta- 
neous 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 sar- 
torius muscle, and in doing so, gives off branches which sup- 
ply that muscle. 

The Internal Cutaneous. 

The Internal Cuta^icoiis is smaller than the middle. It passes 



444 DESCRIPTIVE ANATOMY. 

inward over the femoral arter}^ ; and dividing" into an anterior 
and a posterior branch, passes to the inner side of the thigh. 
The anterior branch communicates with the middle cutane- 
ous while the -posterior branch suns along the edge of the 
sartorius muscle, pierces the fascia lata, and is distributed to 
the integ-ument 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. 

The 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 
exactl}^ the same relation to the femoral artery, with the 
saphenous slightly in front. At Hunter's canal the nerve 
sometimes passes across that fibrous structure, and is 
separated by it from the front of the femoral artery ; but 
usually lies on the femoral arter}^ in Hunter's canal, but not 
in the femoral sheath. At the lower extremity of Hunter's 
canal the nerve passes beneath the tendons of the sartorius 
muscle ; and accompanies that muscle downward to its inser- 
tion, where it pierces the insertion between the sartorius and 
the gracilis to become superficial just below" the knee. It 
now comes into relationship with the internal saphenous vein ; 
and accompanies that vessel 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 g"ives off throug-hout its course cutaneous branches, 
which are distributed throug"hout the course of the nerve. At 
the knee joint it g-ives one large branch, 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 a nerve to the iliacus 
internus, given off while the anterior crural is in the abdomi- 



THE ce:stral nervous system. 445 

nal cavity ; branches to the pectineus (usually two in number, 
thoug-h sometimes but one) which pass beneath the femoral 
vessels ; a separate branch occasionally to the sartorius, thougfh 
that muscle is usually supplied by the middle cutaneous ; and 
a long- branch, already mentioned, the nerve to the vastus in- 
ternus, which is in close relationship to the femoral artery and 
the internal saphenous nerve, enters the vastus internus just 
above Hunter's canal, and there orives branches to the 
vastus externus and to the rectus, each of these entering- 
the corresponding- muscle from its deep surface. 

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 thig-h, the 
sartorius ; 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 thig^h, the tensor vag-ina^ 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 Lumho-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 Sacral Plexus. 

The Sacral Plexus itself is the product of the lumbo-sacral 
cord, with Wio. first, second, third, ■a.nA /ml/ oi the /'oicrt/i sn.craX 
nerves. The fibres entering- into this plexus are more inti- 
mately united than in any other nervous plexus of the body. 
It is triangular in outline, the base of the triang-le extending- 
to the anterior sacral foramina, the apex being- directed down- 
ward and outward to the g-reat sacro-sciatic foramen. 

The Lumho-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 



446 DESCRIPTIVE ANATOMY. 

cord, there being' no such communication, followed by subdi- 
vision, 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 g-reat sciatic 
foramen, 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 second portion of the rectum (more correctly, 
the first portion of the rectum) resting- upon the cords as the}^ 
emerge from the sacral foramina. On the left side, though 
separated 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. 

Way-side Terminal 

Muscular Visceral Gluteal Internal Pudic 

Lesser Sciatic Great Sciatic 
Besides its terminal branches, this plexus also gives off 
certain zvayside, 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 
pyriformis, obturator internus, the gemelli and the quadratus 
femoris. 

The Terminal Branches are the Gluteal, Internal Pudic, 
Lesser Sciatic, and Great Sciatic Nerves. 

The 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 
minimus muscles, where it divides into two branches, superior 
and inferior. The su-perior 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 min- 



THE CENTRAL NERVOUS SYSTEM. 447 

mus, its terminal branch ending- in the tensor vaginas femoris. 
Inferior Gluteal. The lumbo-sacral cord and the first and 
second sacral nerves g"ive oriofin to the second sacral nerve, 
which frequently arising in common with the one above men- 
tioned, is sometimes distinguished as the inferior g-luteal. It 
also passes above the pyriformis muscle through the greater 
sacro-sciatic foramen, and enters the deep face of the gluteus 
minimus muscle, being- distributed to it by a number of small 
branches. 

The Internal Pudic. 

The Internal Pudic Nerve arises from the lower part of the 
sacral plexus, leaves the pelvic cavity throug-h the g-reater 
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 inferior branch, called the Perineal. 

Prior to this division the internal pudic nerve g-ives off an 
Inferior Hemorrhoidal Branch, corresponding- to the artery 
of the same name, which is distributed to the sphincter ani 
muscle and to the integ-ument around the anus. 

Terminal Branches of The Internal Pudic. 

Dorsalis Penis Perineal 

The 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 pubes, accompanying the artery of the same name, 
pierces the suspensory lig-amentof the penis, and runs forward 
upon that org-an to be distributed to the integument that cov- 
ers it and to the corpus cavernosum, while its terminal branches 
end in the g-lans psnis. In its course along- the back of the 
penis it g-ives off lateral cutaneous branches, which are distri- 
buted to the skin upon the sides of the org-an. 



448 DESCRIPTIVE ANATOMY. 

The Perineal. 

The Perineal Nerve, the second branch of the internal pudic» 
divides into two sets of bra.nches, superficial and deep, or cu- 
taneous and muscular. 

The cutaneous branches are two, anterior and posterior, 
and pass upward and forward, to be distributed to the scro- 
tum, perineum, and under surface of the penis, in which latter 
situation 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 majora, the analog-ue of the scrotum 
in the male. 

The muscular branches are distributed to the muscles of 
the perineum ; that is, the transversus perinei, erector penis, ^ 
accelerator urinae and compressor urethrae, these names being" 
g-iven to the muscles in the m.ale subject, each having- its ana- 
log"ue in the female. That branch which passes to the trans- 
versus perinei corresponds to the transverse perineal artery. 
Some deeper branches of this nerve also enter the corpus, 
spongiosum, and supply that body, with its attached muscles. 

The Lesser Sciatic. 

The Lesser Sciatic Nerve usually arises by two roots. It 
passes from the pelvic cavity throug-h the g-reater 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 g-luteus maximus 
muscle. It emerg-es from the lower border of this muscle : 
and pursuing" its course down the back of the thig-h, beneath 
the fascia lata reaches the superior ang-le of the popliteal space, 
where it breaks up into its terminal branches, which after 
being- distributed to the skin covering- the popliteal space, 
anastomose with the cutaneous branch from the g-reat 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 g-luteus maximus muscle, 
that muscle receiving- its nerve supply entirely from the sacral 
plexus, thoug-h some of the fibres pass to it from the inferior 



THE CENTRAL NERVOUS SYSTEM. 449 

g-luteal while the remaining- branches come from the lesser 
sciatic. The latter branches emerg-e 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 thig-h as far down as the popliteal space. One 
branch of larg^e 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 labia in 
the female, communicating- with the superficial perineal and 
the terminal branch of the inferior hemorrhoidal. 

The Great Sciatic. 

The Great Sciatic is the long-est and~ larg-est nerve in the 
body. It appears to be, and in reality is, a continuation of the 
sacral plexus. Triang-ular at its commencement, it soon becomes 
circular in form. It emerg-es from the pelvic cavity below the 
pyriformis muscle throug-h the g-reater sacro- sciatic foramen, 
being- the last of the numerous structures which emerg-e 
from this foramen. These structures are seven in number. 
Two of them pass above the pyriformis, and the remaining- 
five below that muscle. Those which pass above the pyri- 
formis are the g-luteal nerve and artery; those passing- below it 
are the internal pudic, the lesser sciatic and g-reat sciatic nerves, 
the internal pudic and ischiatic, or sciatic, arteries. This does 
not complete the total number of structures which pass 
throug-h this foramen, because in addition should be mentioned 
the pyriformis muscle itself and the companion veins of the 
arteries named. 

After escaping- from the pelvis, the g-reat sciatic nerve 
passesdown the middle of the back of the thig-h, resting- on the 
adductor mag-nus muscle, and covered by the muscles which 
arise from the tuberosity of the ischium. Two of these mus- 
cles, the semi-tendinosus and semi-membranosus, quickly pass 
to its inner side, while the biceps covers the nerve for some 
distance down the thig-h. At the upper ang-le of the popliteal 
space (formed externally by the biceps and internally by the 

Des Anat— 29 



450 DESCRIPTIVE ANATOMY. 

semi-tendiuosus and semi-membranosus muscles) the nerve 
appears between these muscles, called the "ham-string*" mus- 
cles. It then passes into the> popliteal space, and divides into 
its two terminal branches, the Internal and External Popliteal 
Nerve. 

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 
cases at the middle of the popliteal space. As the nerves are 
bound tog-'ether simply by connective tissue, the dissector may 
split them up to any point between the popliteal space and the 
orig"in of the two nerves from the sacral plexus. 

The point of termination usually g^iven for the g"reat sciatic 
is the superior angfle of the popliteal space ; but it rarely di- 
vides before reaching- a lower point, so that the gfreat sciatic 
itself, instead of its internal popliteal branch, becomes a rela- 
tion of the popliteal artery. 

Before dividing- into terminal branches, the great sciatic 
g-ives off muscular branches to supply the posterior femoral 
group, cutaneous branches which communicate with the lesser 
sciatic nerve, and a branch to the adductor magfnus. 

Branches of the Great Sciatic. 

Internal Popliteal Ij^xternal Popliteal 

The Internal Popliteal. 

The Internal Popliteal Nerve, the larg-erof the two terminal 
branches of the g-reat sciatic, commences below the upper 
angle of the popliteal space, to pass throug-h that space, and 
terminate by becoming-theposterior 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 



THE CENTRAL NERVOUS SYSTEM. 451 

Space, opposite the posterior lig-ament of the knee joint, the 
nerve is found directly behind the artery, with the vein inter- 
posed between itself and the artery, while at the termination 
of the popliteal space both nerve and vein have become inter- 
nal 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 corresponds 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 changfino- its name to the Poste- 
rior Tibial. 

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 gas- 
trocnemius below, while to its outer side are, above, the biceps, 
and below, the outer head of the g-astrocnemius and the plan- 
taris 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 distributed in the same way. They anastomose 
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 s^^no- 
vial 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 distributed to the two heads of the gastrocnemius 
and to 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 bor- 



452 DESCRIPTIVE ANATOMY. 

der 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 Branchy the External Saphenous, or 
Communica7is Poplitei, passes downward in the interval be- 
tw^een the two heads of the g-astrocnemius muscle, lies in the 
g-roove upon the posterior surface of the belly of that muscle, 
accompanied by the external saphenous vein ; and, about the 
middle of the calf of the leg-, receives a branch of communica- 
tion from the external popliteal nerve, this branch being- called 
the Conimunicayis Peronei. After receiving- this branch it 
continues downward, with a slig-ht inclination out^yard, passes 
behind the external malleolus, and reaching- the dorsum of the 
foot, is distributed to the integ-ument 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 commumicates with a 
branch of the musculo-cutaneous nerve. 

The 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 orig-in of that vessel, crosses it superficially opposite 
the orig-in of the peroneal branch, and lies for a short distance 
in the interval between the peroneal and posterior tibial arte- 
ries. It then descends to the outer side of the posterior tibial, 
and remains a continuous external relation of that vessel to its 
termination, 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 exter- 
nal plantar branches. 

Branches— Way-Side. 

The Branches of the Posterior Tibial Nerve are muscular 
branches, which supply the tibialis posticus, flexor long-us pol- 
licis, and the flexor long-us dig-itorum. At the ankle joint, 
however, itg-ives off calcanean branches, which, accompanying- 



THE CENTRAL NERVOUS SYSTEM. 453 

the corresponding- arteries, are distributed to the skin on the 

inner aspect of the heel, and an articular branch which supplies 

the ankle joint. 

Terminal or Plantar. 

Internal Plantar External Plantar 

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, aud has a less extended dis- 
tribution, the internal plantar nerve is largfer than the exter- 
nal. The internal plantar nerve corresponds in in its distri- 
bution 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 fing-ers of the median ; while the ex- 
ternal plantar supplies one toe and a half, the equivalent of 
the ulnar of the hand. 

The Internal Plantar. 

The Internal Plantar Nerve passes forward as the companion 
of the internal plantar artery, supplies the inner half of the 
flexor brevis dig-itorura, then continuing- its course it g-ives a 
branch to the abductor pollicis and to the two internal 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 g-reat toe, the second 
to the cleft between the second and g-reat toes, where it divides 
into branches for the inner side of these two toes, the third to 
the cleft between the second and third, and the fourth, after 
giving- off a brauch of communication to the external plantar, 
runs to the cleft between the third and fourth toes and supplies 
the adjacent sides of these toes. 

The External Plantar. 

The Exter7ial Plantar Nerve ^ccom\idimQ^ the external plan- 
tar artery, passes beneath the orig-in of the flexor brevis 
digitorum, and lies between that muscle and the Abductor 



454 DESCRIPTIVE ANATOMY. 

minimi digiti. It then runs forward as far as the posterior 
extremity of the fifth metatarsal bone. It then plunges be- 
neath the second layer of muscles on the sole of the foot, and 
accompanies the arch formed by the external plantar artery. 
In this course it supplies the abductor minimi dig-iti, the outer 
half of the flexor brevis minimi dig-iti, the second layer of 
muscles on the foot, then the flexor accessorious, and the two 
outer lumbricals, and g-ives branches to the interosseous mus- 
cles occupying- the third and fourth interosseous spaces. As it 
passes between the second and third layers of the foot it supplies 
all the muscles of the third layer of the sole. Its digital 
branches are, one to the outer side of the little toe, and one, 
which after communicating- with the internal plantar, divides 
at the cleft between the fourth and fifth toes and supplies the 
adjacent sides of these toes. 

The External Popliteal. 

The External Popliteal nerve beg-ins as a branch of the 
great sciatic, near the upper ang-le 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 fibula, and plung-ing- into the substance 
of the peroneus long-us 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 
mentioned, only momentary, except in those cases in which 
the nerve is so closely bound to the internal popliteal as to di- 
verg-e from that nerve at the middle of the popliteal space. 

Branches. 

Way- j Articular Termi- j Anterior Tibial 

Side \ Communicans Peronei nal ( Musculo-Cutaneous 

In all cases the external popliteal nerve gives oJ0P tzvo articu- 
lar branches corresponding- to the superior external and infe- 
rior external articular arteries, these branches accompanying* 
the arteries and being- distributed in the same way. A recur- 
rent articular branch is also g-iven off which accompanies the 
anterior tibial artery and supplies the front of the knee. 



THE CENTRAL NERVOUS SYSTEM. 455 



The Communicans Peronei. 

Below the knee joint the external popliteal g-ives off the 
Communicans Peronei, which unites with the communicans 
poplitei 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- throug-h the fibres of the pero- 
neus long-US, lies between that muscle and the extensor longus 
dig-itorum. It then passes to the front of the interosseous 
membrane, having- passed obliquely beneath the extensor lon- 
g-us dig-itorum, and becomes a relation of the anterior tibial 
artery, having- the same muscular relations with that vessel ; 
viz., for the upper third to its outer side is the extensor long-us 
dig-itorum, to its inner side the tibialis anticus : in the middle 
third the extensor proprius pollicis to the outer side and the 
tibialis anticus still to the inner side. In the lower third it 
has the extensor long-us dig-itorum 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 interosse- 
ous membrane, 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 joint. 

At the front of the ankle joint the nerve passes beneath the 
anterior annular lig-ament, but does not chang-e 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 
g-reat 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 



456 DESCRIPTIVE ANATOMY. 

crural nerve on the inner side of the great toe, its outer branch 
communicating with the musculo-cutaneous. 

Branches. 

The Anterior Tibial Nerve in its course over the leg supplies 
branches to the tibialis anticus, extensor long-us digitorum, and 
extensor proprius poUicis, while on the outer side it has a 
gangliform enlargement which corresponds to that on the 
posterior interosseous of the forearm from which are given off 
branches to supply the flexor brevis digitorum muscle and the 
tarsal and metatarsal articulations. 

The Musculo-Cutaneous. 

The Musculo-Cutaneous Nerve, after being formed bv 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 tvi/^o perouei muscles and the extensor longus digitorum. 
Running across on the front of the external malleolus, it passes 
on to the dorsum of the foot, where it breaks up into cutane- 
ous branches to supply the toes between the outer face of the 
second toe and 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 
supply the peroneal muscles. As it passes across the external 
malleolus it gives a branch w^hich corresponds to the external 
calcanean branches of the anterior tibial artery; and these 
branches are distributed to the skin on the outer aspect of the 
heel. 

The distribution of the nerve on the dorsum of the foot is 
very irregular. The most frequent arrangement is that it 
communicates on the outer side of the little toe with the exter- 
nal saphenous nerve, then gives a branch which passes to the 
cleft between the little 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 



THE CENTRAL NERVOUS SYSTEM. 457 

nerve, — and a branch to the inner side of the great toe which 
communicates 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 irreg- 
ular as the distribution of the arteries in the same situation. 
In some instances the anterior tibial nerve has been seen to 
suppl}' 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 
oe, or the external saphenous to the extremity of the little toe. 



458 DESCRIPTIVE ANATOMY. 



THE CHANIAL NERVES. 

The crauial 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 throug-h 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 real origin of many of the nerves is still a 
matter of dispute. 

The cranial nerves are named numerically, in pairs, from 
before 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). 
E^ighth Pair, Auditory, (Portio Mollis). 
Ninth Pair, Glosso- Pharyngeal. 
Tenth Pair, Pneumogastric, Par Vagum, Vagus. 
Eleventh Pair, Spinal Accessory. 
Twelfth Pair, Hypoglossal. 

These twelve pairs were formerly considered as only nine 
from the fact that, as will be seen, thej^ 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, 



THE CRANIAL NERVES. 459 

consisted of the seventh and eighth, while the eig-hth consisted 
of the glosso-pharyng-eal, pneumog*astric 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 back- 
ward is WiQ first pair. The first nerve lies on the under sur- 
face 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 perfo- 
rated space. Near the anterior extremity of the anterior cere- 
bral lobe it enlarges into an oval-shaped mass which lies upon 
the cribriform plate of the ethmoid bone and sends its branches 
of distribution 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 com- 
missure from which the two optic nerves diverge forward to 
enter the orbit 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. 

Th.Q/ourth nerve has its apparent orign external to the third, 
on the optic side of the crus cerebri, and also has its exit 
through the anterior lacerated foramen. 

Th.Q 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, 
opthalmic, superior and inferior maxillary, which require three 
apertures of exit from the cranium. 

The opthalmic leaves through the anterior lacerated fora- 
men, the superior maxillary through the foramen rotundum, 
the inferior maxillary through the foramen ovale. 

The sixth nerve takes its apparent origin behind that of the 
fifth from the upper constricted portion of the medulla oblon- 



460 DESCRIPTIVE ANATOMY. 

gata, just behind the pons Varolii, and passes forward to 
gain eg'ress throug-h 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 opthalmic 
branch of the fifth. 

The seventh^ eig'hth, ninth, tenth and eleventh all arise in 
the order named, from above downward, in the g'roove between 
the corpora olivare and restiformia of the medulla oblong-ata. 
The seventh and eig'hth leave the cranium through the same 
opening-, the internal auditory meatus, while the ninth, tenth 
and eleventh all g-ain exit through the posterior lacerated for- 
amen. 

The tzvelfth has its apparent orig-in 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 emerg-es 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 consistsof white fibres and may be traced along the fissure 
of Sylvius into the middle lobe of the cerebrum; the middle 
root is of g"ray 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 forward, 
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 an 
oblong- g-rayish enlargement, called the hnlbiis olfactorius, 
which lies beside the crista g-alli on the cribriform plate of the 
ethmoid bone. From the under surface of the olfactory bulb 
are g-iven off some twenty filaments, which descend into the 
nose throug-h the foramina of the cribriform plate to be distri- 
buted to the mucous membrane of the nose as far down as the 
middle turbinated bone. These filaments are arrang-ed in 



THE CRANIAIv NERVES 461 

three sets, viz: those to the septum, those to the external wall 
and those to the roof of the nose. 

Second Nerve. 

The second ov optic nerve has its apparent orig-in just exter- 
nal 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 cerebra, 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 portion extending- from 
the orig-in to the optic chiasm is called the optic tract. From 
the optic chiasm the two optic nerves diverg-e anteriorly to 
enter the orbit through the optic foramina, each piercing" the 
sclerotic and choroid coats of the eye-ball to expand 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, throug-h 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; and the innermost 
fibres of one nerve pass through the chiasm and become the 
innermost fibres of the opposite nerve, thus accounting for all 
the filaments. 

The Third Nerve. 

The third nerve, or motor ocidi, leaves the brain just to the 
outer side of the crus, near the front of the pons. The deep 
origin can be traced to the locus niger and tegmentum. 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 opthalmic di- 
vision of the fifth below and external to it, and the sixth in- 
ternal 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 



462 DESCRIPTIVE ANATOMY. 

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 g-iven off, the nerve 
supplyingf all the muscles of the ocular g-roup except the ex- 
ternal rectus and the superior oblique. The upper division, 
which passes above the optic nerve, supplies the superior rec- 
tus 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 
g-ang-lion. The branches to the muscles enter on their deep 
or ocular surface. 

The Fourth Nerve. 

The fourth, ox fatheticus, appears just external to the ap- 
parent orig-in of the third on the outer surface of the crus 
cerebri. Its deep orig-in is a nucleus on the floor of the aque- 
duct of Sylvius. After winding- around the crus cerebri the 
fourth pierces the dura below the posterior clinoid process 
and runs forward in the sinus with the third above and the 
opthalmic division of the fifth below it. On reaching- the 
sphenoidal fissure the fourth passes throug-h that fissure at 
its hig-hest and most internal point. On reaching- the orbit it 
crosses over the orig-in of the levator palpebrae and enters the 
superior oblique on the ocular surface of that muscle. It 
communicates with the cavernous portion of the sympathetic 
and g-ives off a small and unimportant branch to the tentorium. 

The Fifth Nerve. 

Theyf/?/^, or trifacial nerve, appears just behind the fourth, 
emerg-ing- from the side of the pons. It has its superficial, or 
apparent origin, by two roots which spring from the lateral as- 



THE CRANIAL NERVES . 463 

pect of the pons, the anterior, consisting- of two or three bun- 
dles, beintr the motor, and the posterior the sensory, root. 
The deep origin is from the floor of the fourth ventricle. 

The two roots pass throug-h the dura just above the internal 
auditory meatus and continue forward to the apex of the pet- 
rous portion of the temporal bone, where a g-angliform enlarg-e- 
ment, called the Gctsserian ganglion, is formed on the posterior 
or sensory root. The motor root passes beneath the g^anglion 
of Gasser without being- connected with it. 

The g"anglion divides into three branches, opthalmic, supe- 
rior maxillary and inferior maxillary. The latter 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 terminal branches the ganglion gives off branches 
to the dura and middle fossa of the skull and receives a com- 
munication from the cavernous plexus. 

The Opthalmic Nerve. 

The opthalmic 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 l^nng below and external 
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 

The Lachrymal branch of the opthalmic pisses 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 fila- 
ments which pierce the palpebral ligament and are distributed 
to the skin of the upper eyelid and communicates with the 
facial nerve. 



464 DESCRIPTIVE ANATOMY. 

The Frontal is tHe largest branch of the opthalmic division. 
It enters the orbit through the sphenoidal fissure, lying- be- 
tween the lachrymal, externally, and the fourth, internally. 
It then runs forward on the levator palpebrae and divides into 
the supra- trochlear ?indi. siipra-orhital. 

The supra-orhital 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 palpebraum, it communicates 
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 fore- 
head. It gives a communicating branch to the infra-trochlear 
branch of the nasal. 

The Nasal Nerve enters the orbit between the heads of the 
external rectus, lies beneath the superior oblique and the levator 
palpebr^ crosses the optic nerve, advances along the inner 
wall of the orbit, re-enters the cranium through the anterior 
ethmoidal foramen and is there found lying in the slit beside 
the crista galli, whence it sinks into the cavity of the nose and 
divides into a branch for the mucuous 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 for- 
ward to emerge at the inner angle of the orbit below the fovea 
trochlearis and supply the lachrymal sac and inner angle of the 
eye. Besides the infra-trochlear it gives off in the orbit three 
other branches; one to the opthalmic g-anglion of the sympa- 
thetic 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 division of the fifth nerve, like the 
opthalmic, has a forward course. It gains egress through the 



THE CRANIAL NERVES. 465 

foramen rotundum, continues its forward direction across the 
spheno-maxillary fossa, along- a g-roove on the floor of the orbits 
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 
maxillary are the following-, emitted in the order g*iven: 

The orbital or tem^oro-iualar .hr-a^woh. enters the orbit throug-h 
the spheno-maxillary fissure and divides into two branches, 
temporal and malar. The temporal branch enters the tempo- 
ral fossa through the outer wall of the orbit, while the malar 
branch continues along- the outer wall of the orbit to emerg-e 
on the cheek at the outer angle. 

The sfiheno-palatine are two branches of communication 
which descend to Meckel's g-ang-lion of the sympathetic in the 
spheno-maxillary fossa. 

The chief distribution of the superior maxillary is to the 
teeth and g-ums of the upper jaw and this is effected by two 
branches, anterior and -posterior dental. The -posterior dental 
is first emitted and supplies the molar and bicuspid teeth. 

The anterior dental leaves the main trunk just as it is about 
to emerge on the face and supplies the two incisors, the canine 
and the front bicuspid. The anterior and posterior dental 
nerves anastomose in the bone and supply each tooth with as 
many filaments as the tooth has fangs, besides g-iving- twigs 
to the g-ums. 

Inferior Maxillary Nerve. 

The inferior maxillary division of the fifth nerve consists 
of a branch from the gang-lion of Gasser and the small motor 
root of tiie fi fth nerve, which unite and pass downward throug-h 
the foramen ovale, immediately after emerg-ing from which 
the nerve divides into an anterior and ^.posterior 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 

Des Anat— 30 



466 DESCRIPTIVE ANATOMY. 

the muscle to which it -is distributed and conveying' motor 
influence. 

The masseteric branch runs out above the external ptery- 
goid muscle, crosses throug'h the sig^moid notch and is dis- 
tributed to the deep face of the masseter. 

The deef temporal branches anterior and -posterior, are 
distributed to the deep face of the temporal muscles. 

The buccal branch pierces the external pteryg"oid, some- 
times lying- beneath the coronoid process and sometimes run- 
ning- through the temporal muscle, to be distributed 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 p>osterior trunk divides into three branches, inferior 
dental, gustatory and auriculo-temporal. 

Inferior Dental. 

The inferior dental branch curves forward and downward 
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 ?7iylo-hyoidean, which de- 
scends along the groove on the inner surface of the inferior 
maxilla and is distributed to the mylo-hyoid muscle and the 
anterior belly of the digastric. 

Gustatory Branch. 

The gustatory nerve passes downward and forward, first 
behind the external pterygoid muscle, 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 



THE CRANIAL NERVES. 467 

oro-an. While between the two pter^^gfoid muscles it receives 
at an acute angle the chorda tympani a branch of the seventh 
nerve, which it transmits to the submaxillary g-ang-lion of the 
sympathetic. Beneath the tono-ue the gustatory gives off a 
branch of communication to the twelfth. 

It distributes branches to the filiform and fungiform papillae, 
the mucous membrane of the tongue, mouth, and gums. 

Auriculo-Temporal. 

The auriculo-temporal branch arises by two roots. 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 paro- 
tid 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 pons, 
while its deep origin can be traced to a mass of gray matter 
lying in the floor of the fourth ventricle. The nerve, after 
piercing the dura over the sphenoid, runs through an opening 
in the dura just below the posterior clinoid process and 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 opthalmic vein, runs 
between the two heads of the external rectus and is distributed 
to that muscle from its deep surface. 

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 restiformia. Its deep 
origin is from the floor of the fourth ventricle, where it com- 
municates with the sixth nerve. Just beneath it, in the same 



468 DESCRIPTIVE ANATOMY. 

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 spring-ing- 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 Pallopius, which conducts it first outward, 
then backward and then downward to the stylo-mastoid fora- 
men, emerg-ing- from which it passes forward through the 
parotid g-land, over the external carotid artery, and divides 
into numerous branches which are distributed to all the mus- 
cles of the face except those of mastication, and of these the 
buccinator g-ets a branch. 

Branches. 

Ivike 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 audi- 
tory nerve. In the aqueductus Fallopii the larg-e su-perficial 
petrosal is sent to Meckel's g-ang-lion, the small -petrosal to 
the otic g^ang-lion and the external petrosal to the sympathetic 
on the middle meing-eal artery. After the nerve emerg-es 
from the stylo-mastoid foramen, communications are estab- 
lished with the ninth and tenth cranial nerves, with the caro- 
tid 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. 

The branches of distribution the tympanic and chorda tym- 
■pani, arising" within the aqueductus Fallopii ; the posterior 
auricular, stylo-hyoid and dig-astric arising- outside the stylo- 
hyoid foramen, and two terminal branches, the temporo-facial 
and cervico-i?i.QA'al. 

The tympanic, which arises from the facial while it is in 
the aqueduct of Fallopius and is distributed to a muscle of the 
tympanic cavity. 

The chorda tympani, which is emitted from the facial just 



THE CRANIAL NERVES. 469 

above the stylo-mastoid foramen and first ascends throug"h 
the petrous bone and enters the tympanum at the base of the 
pyramid on its posterior wall, then crosses on the inner surface 
of the membrana tympani and leaves throug"h the fissure of 
Glaser, having- emerged from which it joins the gustatory 
branch between the two pteryg-oid muscles and continues with 
it to the submaxillary g-ang-lion. 

The stylo-hyoid which supplies the stylo-hyoid muscle. 

The digastric, which is distributed to the posterior belly of 
the dig-astric muscle. 

The posterior auricular, which ascends behind the ear and 
after communicating" with the auricular branch of the pneumo- 
gastric is distributed by an anterior branch to the auricle and 
by a posterior to the back of the head. 

The temporo-facial \^ the larg-er of the two terminal branches 
of the seventh. It passes throug-h 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 
orbicularis palpebraum muscles; the second the orbicularis and 
corrug-ator supercillii, while the last, the largest branch, sup- 
plies the pyramidalis nasi, levator labii superioris and levator 
anguli oris. 

The cervico-facial d\v'\'^\ovL passes downward in the substance 
of the parotid gland, which separates it from the external 
carotid. It communicates with the auricularis magnus and 
divides into <^2^cc«/ 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 eig-Jith 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 



470 DESCRIPTIVE ANATOMY. 

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 g-losso-fharyngeal, is the third nerve 
arising" in the g-roove between the corpora olivare and 
restiforme. Its deep orig-in is from the floor of the fourth 
ventricle between the eig^hth and tenth. It escapes from the 
cranium, along- with the tenth and eleventh, throug"h the pos- 
terior foramen lacerum, lying- behind the internal carotid 
artery ; it then passes forward between the artery and the in- 
ternal jug-ular vein to the outer side of the artery, then crosses 
the artery in front 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 poste- 
rior part of the tong-ue. 

This nerve presents two g-ang-liform enlargements called 
superior, or jug'ular, and inferior, ov petrous. The superior 
which is very small, is situated in the jug-ular foramen and 
does not involve all the fibres of the nerve. The inferior 
g-ang-lion is situated in a depression on the posterior border of 
the petrous portion of the temporal bone and g-ives off branches 
of cummunication to the pneumog-astric and sympathetic. 

Branches. 

Besides its terminal branches the ninth nerve g-ives off four 
branches of distribution. 

The tympanic branch, Jacohson s nerve, passes to the tym- 
panum throug-h a canal which opens on the ridg-e of bone be- 
tween the carotid and jug-ular foramina. After reaching- the 
tympanum it is distributed by six branches, as follows: 

{(i) One to the lining- membrane of the tympanum and E^usta- 
chian tube. 

(^) One to the fenestra rotunda. 

{c) One to the fenestra ovalis. 

{d) One to the carotid plexus of the sympathetic. 

{e) One to the g-reat superficial petrosal nerve. 
(_/) One to the lesser superficial petrosal nerve. 



THE CRANIAIv NERVES. 471 

A muscular branch which supplies the stylo-pharyngeus. 

The ■pharyngeal branches, which are found on the poste- 
rior part of the pharynx aiding- to form a plexus called the 
pharyngeal from which the pharynx is supplied. The other 
nerves antering- into the formation of this plexus are the phary- 
geal 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 gangflion of the tenth nerve. 

One to the superior cervical ganglion of the sympathetic. 

One to the seventh nerve. 

Carotid filaments which descend with the carotid artery. 

Tenth Nerve. 

The tenth nerve, or pneiunog'astric, or par vag'um, is the 
fourth nerve arising from the g-roove 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 left to rig-ht along 
the lesser curvature of the stomach. In the neck the course 
and relations of the nerve are the same on both sides, /. <?., 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 rig-ht nerve at the root of the neck crosses the first portion 
of the subclavian artery, enters the chest, reaches the posterior 
aspect of the root of the right lung; descends thence along the 
posterior aspect of the (esophagus 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 portion 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 
alonL*" its lesser curvature and is distributed to its anterior face. 



472 DESCRIPTIVE ANATOMY. 

While in the jug-ular foramen the nerve presents a gang-liform 
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 commiinicating and branches 
of distribution. The communicating are mainly connected 
with the two ganglia on the nerve. The gang-lion of the root 
receives branches from the accessory portion of the spinal ac- 
cessory, the petrous ganglion of the ninth, the auricular branch 
of the facial and from the superior cervical of the sympathetic. 

The g-ang-lion 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 Thoracic Cardiac 

Pharyngeal Anterior Pulmonary 

Superior Laryngeal Posterior Pulmonary 

Recurrent Laryngeal (Ksophageal 

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 auricular, 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 
portionof the temporal, where it communicates with the facial, 
leaves the temporal through the auricular fissure and is dis- 
tributed 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 
ni ith, superior laryngeal and the sympathetic to form the 
pharyngeal plexus. 



THE CRANIAL NERVES. 473 

The superior laryngeal branch arises from the g-ang-liou of 
the trunk and descending- pierces the thyro-hyoid membrane 
and is distributed to the mucous membrane of the larynx, g-iving- 
a filament to the arytenoid muscle. Just below the thyro- 
hyoid membrane it g-ives off a branch called the external 
laryngeal, which is distributed to the thyroid g-land and crico- 
thyroid muscle and furnishes some filaments to the pharyng-eal 
plexus. 

This nerve receives a communication from the eleventh and 
afterward communicates with the recurrent laryng-eal and with 
the pharyng-eal plexus. In its course down the neck it lies 
bv the side of the pharynx and crosses behind the internal 
carotid artery. 

The recurrent or inferior laryng-eal branch arises at a differ- 
ent point on each side; on the left it arises as the pneumog-as- 
tric is crossing- the aorta and winds backward around the 
aorta; on the rig-ht it arises as the nerve is crossing the first 
portion 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 
oesophagus, giving- filaments to those parts, and is distributed 
to all the 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 infe- 
rior constrictor. 

The cervical cardiac branches are divided into superior and 
inferior. The superior usually join 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 come entirely from the right 
nerve (all the left thoracic coming from the recurrent laryngeal) 
and 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. 



474 DESCRIPTIVE ANATOMY. 

The anterior -pulmonary branches form a smaller plexus 
on the front of the root of the lung-. 

The oesophageal branches are filaments furnished the 
oesophag-us before the nerves are in relation with it. 

The two nerves communicate frequently around the tube, 
surrounding- it with numerous anastomoses, thus forming- the 
oesophag-eal plexus. 

The g-astric, or ter^nmal, branches are distributed to both 
faces of the stomach, the rig-ht nerve g'oing- to the back, and 
the left to the front, of that org-an. The two communicate 
with each other and with the caeliac, splenic, and hepatic 
plexuses. 

Eleventh Merve. 

The eleventh nerve, or spinal accessory, is the fifth nerve 
arising- in the g-roove between the corpora olivare and resti- 
forme and escapes from the cranium throug-h the posterior 
foramen lacerum along- with the ninth and tenth nerves. The 
nerve consists of two portions: 1st, a cranial or accessory por- 
tion which arises from the g-roove mentioned and, after com- 
municating- with the cervical portion, g-oes to the pneumog-as- 
tric ; 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 throug-h the foramen mag-num and after 
communicating- with the accessory portion emerg-es through 
the jug-ular foramen, passes downward and outward, pierces 
the sterno-cleido-mastoid muscle and reaches the trapezius to 
which it is distributed, g-iving-, 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, or hypoglossal, arises from the g-roove 
between the corpora olivare and pyramidale by ten or twelve 
filaments which are g-athered into two bundles : these pass 
outward and, just as they are leaving- the cranium throug-h 



THE CRANIAL NERVES 475 

the anterior condyloid foramen, unite to form the trunk of the 
nerve. The nerve then descends between the internal jugu- 
lar vein and internal carotid artery and, w^hen it reaches a 
point on a level with the jaw, curves forward in front of both 
internal and external carotid arteries, and after communica- 
ting- with the gustatory nerve is distributed to the muscles 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 
crossing 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 
descending in the sheath. About the middle of the neck it 
anastomoses with filaments from the second and third cer- 
vical nerves, the communicans noni, forming what is called 
the arch of Scarpa, which lies in front of the sheath of the com- 
mon 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 termination 
of the hypoglossal nerve to supply the thyro-hyoid muscle. 



476 DESCRIPTIVE ANATOMY. 



THE SYMPATHETIC NERVES. 

The sympathetic nervous system consists of a vertebral and 
a cranial portion. 

The Vertebral Portion. 

The vertebral -portion of the sympathetic consists of two 
similar series of gfang-lia, lyinof one on each side of the verte- 
bral column, extending- from the skull to the coccyx, and the 
nerves which are connected with these g^anglia. Of these 
gang-lia 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. I)ach gang-lion is provided with four sets o f 
branches: 1st, ascending to connect it with the ganglion above; 
2d, descending to connect it with the ganglion below; 3rd, 
external to connect it with the contiguous spinal nerve; 4th, 
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 filaments, 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 regions; 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 prevertebral sympathetic. As a rule each gang- 
lion is connected with but one spinal nerve, but to this there 
are exceptions, which will be found in the cervical portion. 

Cervical Portion. 

The cervical -portion of the sympathetic is that part of the 
chain or trunk which is found in the cervical region. Although 



THE SYMPATHETIC NERVES. 477 

there are eig-ht cervical spinal nerves, there are only three 
sympathetic g^anglia, 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 seg^mented so as to 
correspond to the four upper cervical vertebrae. It receives 
communications, by means of its external branches, from the 
first, second, third, and fourth cervical nerves, and also smaller 
branches from the g-losso-pharyngeal, pneumogfastric, and 
hypo-gflossal nerves. This trang*lion 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 g-anglion passes 
downward behind the common carotid artery, resting upon 
the prevertebral g-roup 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 gfang-lion. 

Its branches of distribution are three in number, viz., the 
pharyng-eal, which unite with branches of the g-losso-pharyn- 
g-eal 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- 
vessels, and glands of that organ. The laryngeal brandies 
unite with the superior laryng-eal branch of the pneumog-astric, 
and form a plexus distributed to the larynx. The last branch 
is given to the heart, and is called the superior cardiac, to 
distinguish it from smaller branches derived from the middle 
and inferior cervical g-anglia. This is a long-, slender nerve, 
which passes down the neck behind the common carotid artery, 
crossing- on the rig-ht side, sometimes behind, sometimes in 
front of the first portion of the subclavian artery, while on 



478 DESCRIPTIVE ANATOMY. 

the left side it passes behind the thoracic portion of the sub- 
clavian. 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 g-reat superficial cardiac 

plexus. 

The Middle Cervical Ganglion. 

The Middle Cervical Gang-lion is situated opposite the 
fiftn cervical vertebra, is very small in size, and is frequently 
entirely absent. 

Its superior branch communicates with the upper cervical 
gangiion, 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 
middle 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 commumicating with the superior car- 
diac and a branch of the recurrent and external laryngeal 
nerves, it 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 trachea, and, after receiving filaments from the recurrent 
laryngeal nerve, joins the great deep cardiac plexus. On the 
left side it enters the chest between the left common carotid 
and the subclavian arteries, and joins the deep cardiac plexus. 

The Inferior Cervical Ganglion. 

The Inferior Ganglion is situated between the base of the 
transverse processes of the last cervical and the first dorsal 
vertebrse. It is probably the product of the last two cervical 
nerves, the two ganglia having coalesoed 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 gang- 
lion, when that ganglion fails to coalesce with the last cervical. 



THE SYMPATHETIC NERVES. 479 

Its exteriml fibres are derived from the last two cervical 
nerves, the seventh and eigfhth, while its internal brunch is 
the last of the three cardiac nerves. It communicates with 
the recurrent laryng-eal and middle cardiac nerve; and then 
passing- into the thoracic cavity, unites with the deep cardiac 
plexus. 

The Cardiac Nerves. 

It vt^ill be seen that there are two larg"e plexuses connected 
with the heart and supplying- the muscular fibres of that org-an. 
These are known as the ^;'e«/ deep cardiac plexus and the 
superficial cardiac plexus. 

The Superficial Portion is found lying- on the ductus arte- 
riosus, and is the product of the superior cardiac nerve of the 
left side and the inferior cervical cardiac branch of the pneu- 
mogastric. 

The Deep Plexus, situated in the bifurcation of the trachea, 
is formed by the three cardiac nerves of the rig-ht 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- 
g-astric; while the deep cardiac plexus is formed by the three 
rig-ht cardiac branches from the sympathetic, the left, middle 
and lower sympathetic, and the cardiac branches of the rig-ht 
pneumog-astric. 

From these two plexuses branches proceed, which following 
the course of the coronary arteries, are distributed along- these 
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 
g-ang-lia on either side of the body, corresponding- to the number 
and position of the dorsal vertebrae. These g-ang-lia are uni- 
fcjrmly arrang-ed, and consist, like other sympathetic g-ang-lia, 
of ascending- branches communicating- with the g-ang-lion above, 
descending- branches communicating- with the g-anglion below, 
external, which are usually two branches and communicate 



480 DESCRIPTIVE ANATOMY. 

with the corresponding- dorsal nerves, and internal which are 
branches of distribution. 

The Branches of Distribution, coming- from the dorsal 
sympethetic are almost entirely confined to the abdominal 
cavity. They form three nerves, known as \)a^ greater, lesser, 
and least S-planchnic. 

The internal branches of the g-angflia are divided into two 
sets : the upper and small ones are distributed along- the 
branches of the thoracic aorta ; w^hile of the lower ones, those 
between the sixth and tenth g-ang-lia unite to form the great 
sflanclmic nerve, the tenth and eleventh gfanglia form the 
lesser splanchnic, and the leasj:, 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 corre- 
sponding- crus of the diaphrag-m, and enters into the semi-lunar 
g-ang-lion of its side. 

The Lesser Splanchnic Nerve, the product of the tenth and 
eleventh g-ang-lia, also pierces the crus of the diaphrag-m. and 
joins with the coeliac plexus ; while the smallest, or least 
Splanchnic terminates in the renal plexus. 

The SeTni-lunar Ganglia, found on either side of the coeliac 
axis, is apparently an enlarg-cment of the g-reater splanchnic 
nerve. Each g-ang-lion g-ives off branches which communicate 
with the g-ang-lion of the opposite side, forming- a complete 
net-work surrounding- the lateral and anterior aspects of the 
abdominal aorta, and completely enveloping- the coeliac axis. 
These numerous branches are collectively known as the Solar 
Plexus of Nerves. 

From this solar plexus larg-e branches follow the three 
arteries into which the coeliac axis divides ; and, formings 
plexuses along- the course of these vessels, known as the Gas- 
tric, Hepatic, and Splenic Plexuses, are distributed to the 
org-aus which these vessels supply and to the coats of the 
vessels themselves. 

The Lesser Splanchnic, after piercing- the diaphrag-m, enters 
into the coeliac plexus; and some of its branches accompany 
the ramifications of the arteries mentioned above, while other 



THE SYMPATHETIC NERVES. 481 

■filaments descend to the renal plexus, where that communicates 
with the least splanchnic nerve. 

The Least Splcaic/niic, after piercing- the diaphrag-m, 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 distributedalong 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 Inipar, or terminal ganglion of the sympathetic 
system. 

The Lumbar Portion of the Sympathetic. 

The Lumbar Portion of the Sympathetic System is contin- 
uous above with the dorsal by means of the branch which 
passes from the last dorsal sympathetic g^ang-lion beneath the 
ligamentum arcuatum to the first lumbar. The lumbar 
ganglia vary in number, being from three to five. 

They receive their branches of communication from the 
lumbar spinal nerves, a descetiding branch of communication 
from the ganglion above, and give a communicating- bra)/ch to 
the ganglion below. These ganglia lie along the inner side 
of the psoas magnus muscle, where they receive communicating- 
branches from the lumbar nerves. 

Of the internal brandies 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 
communication 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- 

Des An at — 31 



482 DESCRIPTIVE ANATOMY. 

ferior mesenteric and the spermatic arteries and to the inferior 
vena cava. 

The lower internal brmiches 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 wath 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, corre- 
sponding to the arteries which pass to them, the branches 
being the Inferior Hemorrhoidal, Vesical, and Prostatic in the 
male, and Vaginal -aM^ Uterine in the fem^de, finally terminates 
by uniting over the mid-line of the body to form the Ganglion. 
Impar, or termination of the sacral plexus of 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. E)ach 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 branch- 
es form the roots of the ganglion. The four cranial ganglia 
are the opthalmic, the spheno-palatine, the otic and the 
submaxillar3^ 

Opthalmic Ganglion, or Ciliary Ganglion. 

The opthalmic 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 opthalmic artery. It is small and reddish gray 
in color and receives three roots, or branches of communication. 

Its sensitive root is furnished by the nasal nerve ; its 
motor root by the branch of the third nerve sent to the infe- 



THE SYMPATHETIC NERVES. 483 

rior oblique muscle ; its synifiathetic root by the cavernous 
plexus. The sympathetic root frequently blended with the 
long- or sensory root. 

Its brcniclies of distribiitioii^ 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 sphe)io-palati)ie, or MeckeV s gang'lion, is the larg-est 
of the cranial g-ang-lia and is found lying- in the spheno-max- 
illary fossa just beneath the superior maxillary division of the 
fifth nerve, and close to the spheno-palatine foramen. 

Its sensitive roo/ consists of two filaments from the superior 
maxillary nerve: its motor root is derived from the facial nerve 
throug-h the Vidian ; its sympathetic root is from the carotid 
plexus. The last two roots reach the g^ang-lion tog^ether, 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 g-reat superficial petrosal 
nerve, g-oing- to tne facial throug-h the hiatus Fallopii. The 
branches of distribution of this g-angflion are four, palatine 
pharyng-eal, superior nasal and naso-palatine. 

The three palatine branches, anterior, middle, "ajvA posterior, 
descend to supply the roof of the mouth, soft palate and ton- 
sils. The anterior palatine passes downward throug-h the 
posterior palatine canal, emerg-es 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 g-iven oif to the nose, the inferior 
nasal, which supplies 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, ofteu absent, g-ives branches to the 
tonsils, uvula and solt palate. 

The posterior palati)ie passes throug-h an accessory palatine 
canal to supply the levator palati and azyg-os uvulai. 



484 DESCRIPTIVE ANATOMY. 

The su-perior 7iasal are four or five branches which enter 
the nose through the spheno-palatine foramen and are distri- 
buted 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- branchesr 
to it, enters the palate through the naso-palatine canal. 

The pharyngeal branches, or -pteryg-o-palatine, passes 
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 Pallopii 
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 Gang-lion, 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 
pterygoideus internus; 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 petrosus superficialis 7ninor, which first enters 
the cranium through a canal between the foramen ovale and 
foramen 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 SYMPATHETIC NERVES. 485 

The Submaxillary Ganglion. 

The submaxillary g-ang-lioii is a minute speck situated near 
the posterior border of the mylo-hyoid muscle. It receives 
filaments 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 
submaxillary g-land. 



486 DESCRIPTIVE ANATOMY. 



THE OUILET 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 sur- 
rounded 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 pubesand backward 
from it the greater sacro-sciatic lig-ament or, in the recent sub- 
ject, the lower border of the g"luteus maximus muscle. In the 
recent subject the outlet of the pelvis is divided into two por- 
tions by a transverse line passing- between the anterior edg-es 
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 portion lying- in front of this line is called th.Q perineum 
and that lying- behind it the ischio-rectal region. 

Ischio-Rectal Region. 

The ischio-rectal region is bounded in front by the transverse 
line, behind by the apex of the coccyx, laterally by the g-reat 
sacro-sciatic lig-ament or the lower edg-e of the g-luteus maximus 
muscle and the tuberosity of the ischium. It contains three 
parts to be examined, the anal orifice with its sphincter mus- 
cle and, on each side of this, a subdivision known as the ischior 
rectal fossa. 

Anus. 

The anus is the termination of the rectum, and is kept 
habitually closed by the tonic contraction of muscles called 
sphincters, internal 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 muscular 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 



THE OUTLET OF THE PELVIS. 487 

Sphincter ani externus. It arises from and around the tip of 
the coccyx and passes forward just beneath and closely adher- 
ent 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 
without, 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 
side is the obturator internus muscle. The levator ani mus- 
cle is thin and flat and has a most peculiar origin, to undestand 
which some preliminary remarks are necessary. The trans- 
versalis fascia, which lies between the transversalis abdomi- 
nis muscle and the parietal layer of the peritoneum, when it 
reaches the iliac fossa, where it covers the iliacus internus 
muscle, takes the name of 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 
commencement of the obturator foramen, divides into tw^o 
layers, one of which, the external, passes over the inner face 
of the obturator internus, as the obturator fascia ; while the 
other passes to the base of the bladder and the side of the rec- 
tum as the recto-vesical fascia. Now just in the interval left 
by the splitting of the pelvic fascia the levator ani rises, hav- 
ing internal to it the recto-vesical fascia and external, with a 
widening interval between them, the obturator fascia. Besides 
this origin from the fascia, it arises posteriorl}'^ 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 absorption of which, in long-continued, 
debiliating desease, is the cause of the sunken appc.irmce 
seen there. 



488 DESCRIPTIVE ANATOMY. 



Perineum — In the Male. 

The perineum is that sub-division of the outlet of the pelvis 
which lies in front of the transverse line. Its limits are as 
follows : In front the public arch, behind the transverse line, 
on each side the rami of the pubes and ischium. Crossing- 
along- its centre from behind forward, and continued on to the 
scrotum, is a ridg-e of the integ-ument called the raphe. 

Upon careful dissection the perineum is found to be formed 
of the following- constituents from the surface upward, viz : 

1st. Integument. 

2d. Several layers of superficial fascia which in no wise 
differ from the g-eneral superficial fascia found beneath the 
integ-ument everywhere. 

3d. A layer of fascia called the superficial permealia.sci3.,since 
it is peculiar to the perineum, being- attached to the rami of the 
ischium and the p