ANATOMY. 
92 
the eye above it? adductor, divides it 
into two branches. 
2. The communicating artery. — This, 
along with the deep branch of the verte- 
bral artery of the cerebrum, forms the 
circle of Vi illis. It proceeds straight 
backward and inward, near the infundi- 
bulum, where it reaches the artery al- 
ready mentioned, and there seems an 
obtuse-angled quadrangle. 
3. The anterior carotid artery, or ar- 
terial callosa. — The internal carotid at 
that place where the anterior lobe of the 
brain is separated from the posterior, di- 
vides into two branches of nearly equal 
size ; of which the anterior proceeds 
immediately inwards, and a little for- 
wards ; then bends above the corpus 
callosum, between the hemispheres, to 
the posterior lobes of the brain. 
4. The posterior carotid, or the artery 
of the fossa sylviana, enters the fossa 
sylvii, and gives to each numerous su- 
perficial and deep-seated branches to 
both lobes of the brain. 
Distribution of the subclavian artery and its 
branches. 
The division of the right and left subcla- 
vian artery differs only in this respect, that 
the right subclavian is much larger, passes 
obliquely over the trachea, and sends off the 
common carotid. Having left this branch at 
the side of the trachea, it is now more pro- 
perly the right subclavian ; and, still continu- 
ing larger than the left, proceeds nearly in a 
transverse direction. The left subclavian, on 
the other hand, while it gradually ascends 
from the inclining part of the arch, passes on 
to its place of destination with a more rapid 
and extensive curvature. 
These two arteries run in such a direction 
above the superior margin of the lirst rib, as 
to be concealed for some time by the clavi- 
cle. They then proceed with the brachial 
plexus, across that space lying between the 
first and second scalene muscles ; and being 
covered by the flattened extremity of the 
clavicle and pectoral muscle, bend to the 
axilla;, where they take the name of axillary 
arteries. The branches of the subclavian 
arteries, and their ramuli, present so many 
varieties, that no description, either as to 
their number or their direction, can in every 
respect correspond with nature. In general, 
however, the four lirst branches arise before 
the artery sinks under the scalenus, while the 
rest are sent off beyond the margin of this 
muscle. These are, 
1 . The internal mammary — going off from 
the lower and anterior part of the trunk 
at the highest part of the pleura, where 
ascending gradually, and again bending down- 
wards to the sternum, it reaches the mar- 
gin of the first rib, under which it passes; 
and running between the pleura and middle 
part of the cartilages of the ribs, descends be- 
tween the internal’ intercostal and their sterno- 
costal muscles, as far as the diaphragm. It 
then passes between the diaphragm and the 
ribs, and dividing into many twigs, it is lost 
under the rectus of the abdomen, from its 
origin to the third rib. It bends towards the 
Sternum, then gradually inclines outward. 
2. The inferior thyroid or anterior cervical 
artery, rising from the fore part of the trunk, 
near the mammary and vertebral arteries; 
and being covered by the sterno-mastoid, and 
bent a little upwards and outwards, immedi- 
ately divides into four principal branches ; 
the transverse scapular, the transverse cer- 
vical, the ascending thyroid, and tlxe thyroid 
branch of the thyroid. 
3. The superior intercostal artery rises 
more externally than the vertebral, from 
the upper and posterior surface of the 
trunk, then ascends with it to the hol- 
low, then it is formed by the anterior 
scalenus, the surface of the first rib, and 
bodies of the vertebra. It is there sud- 
denly reflected, and proceeds to the roots 
of the first and second ribs within the 
thorax. 
4. The vertebral artery, larger than 
the former, rises from the superior side 
of the subclavian ; and ascending a little 
backwards, covered by the ganglions of 
the intercostal and cellular membranes, 
reaches the perforations of the transverse 
processes of the cervical vertebra ; thro’ 
these it penetrates, and rising perpen- 
dicularly from the sixth or sometimes 
from the fifth or fourth opening, reaches 
the aperture of the atlas, where it bends 
a little outwards, and having passed 
through, undergoes another more ex- 
tensive llexion backwards and inwards, 
by which it is carried transversely in a 
groove between the occipital bone and 
the atlas, to the foramen magnum. 
Through this opening having at last en- 
tered the cranium, it proceeds upwards 
and forwards, and at the basilar apophy- 
sis, under the medulla oblongata, meets 
at an acute angle with the vertebral ar- 
tery of the opposite side, forming the 
basilar artery, to be distributed to the 
cerebrum and cerebellum. 
The basilar artery, being formed as above, 
occupies the depression in the middle of the 
tuber annular, and at its anterior part divides 
into four parallel branches, proceeding from 
the trunk at right angles. Of these the poste- 
rior go to the cerebellum, and the two ante- 
rior, ramified on the cerebrum, unite with 
communicating arteries of the carotid, and 
form the great circle of Willis. 
5. The deep or posterior cervical ar- 
tery, irregular in its origin, size, and ex- 
tent, and like the superficial cervical or 
transverse scapula of the thyroid, spreads 
sometimes more and sometimes less ex- 
tensively with its branches. We have some- 
times observed it the smallest of all, and- 
proceeding from the superior intercostal, 
it generally issues from the subclavian, 
beyond the margin of the scalenus, though 
sometimes sooner under this muscle. It 
■ then winds upwards and backwards be- 
tween the deep muscles of the back and 
the sixth vertebra ; and is at least so dis- 
persed among the muscles as to bestow 
its ultimate branches on the complexus 
near the occiput. 
6. The superficial cervical rises about 
half an inch or an inch from the lirst sca- 
lenus at tiie upper and anterior side of 
the subclavian, where it begins to bend 
downwards, and immediately hides itself 
among the brachial nerves ; and spread- 
ing out afterwards toward the superior 
costa scapula, divides into many irregu- 
lar branches. 
Distribution of the axillary artery. 
The subclavian artery, as it bends from it's 
first situation between the breast and scapula, 
to the humerus, assumes the name of axillary. 
Passing out under the arch of the clavicle, it 
is surrounded by the nerves of the brachial 
plexus, the veins, glands, and a quantity of fat; 
lies in the hollow of the axilla, between the 
subscapuiar and serratus major ; and protect- 
ed externally by the pectoral muscles, it soon 
approaches forwards to the arm and interior 
margin of the biceps. At last, proceeding 
from the axilla to the inferior border of the 
tendon of the latissimus dorsi, it takes the 
name of the humeral artery. It sends off, 
1. The thoracics. 
2. The inferior scapular, or infrasca- 
pular, or subscapular, rising in the infe- 
rior margin of the subscapular muscle, 
divided into conspicuous branches, which 
run in various directions. 
3. The posterior circumflex artery, 
issuing between the subscapular and ! 
teres major ; it sinks between them, 
winds round the neck of the humerus, 
under the long extensor, and afterwards j 
bends transversely under the deltoid, 
backwards and outwards from the inner 
side of the arm. It sometimes gives rise 
to the anterior circumflex, and the deep 
branch of the humerus or humeral pro- 
funda. 
4. The anterior circumflex artery, of 
smaller size, sent out near the former, 
above the teres major, proceeds round 
the humerus, under the biceps and co- 
raco-brachial to the outer part of the 
arm, where it either disappears under 
the deltoid, or enters this muscle. 
Distributionofthe brachial or humeral artery. 
The axillary artery is first known by the 
name of the humeral or brachial, where it 
proceeds from, the axilla to the internal side] 
of the arm. Having left the cavity of the- 
axilla, and passed to the internal surface of 
the tendon of the feres major, it continues its 
course above the internal brachial to the in- 
ner side of the biceps, and gradually runs 
along the middle of the arm to the anterior 
surface of its- extremity ; where at last, con- 
cealed under the aponeurosis of the biceps, 
it divides near the bend of the fore arm into 
the ulnar and radial arteries. 
1. The deep branch of the humerus,-, 
the large collateral, or large humeral 
profunda, sometimes double, rising from'- 
the inner side of the trunk, at the infe- 
rior margin of the teres major ; but- 
sometimes sooner, from the inferior sca- 
pular, or posterior circumflex. 
It proceeds backward with a gentle curve 
and, accompanying the extensor, runs to the - 
cavity between the anconei muscles, where,! 
in the passage of the spiral nerve, it divides 
into two branches, at the upper junction of 
the external anconeus and internal brachial. 
2. The large anastomotic, rising some- 
times double from the internal side of 
the trunk, a few inches above the joint ; 
but immediately dividing, it passes in a 
transverse course upon the surface of the- 5 
internal brachial to the flexor condyles, : 
where, perforating the intermuscular li- 
gament, it runs upward to the cavity, 
between the condyle and olecranon, co- 
vered by the tendon of the biceps and 
the ulnar flexor of the carpus. 
The ulnar artery. — The humeral artery 
