ANATOMY, 
sometimes undergoes the division already 
mentioned at the middle of the humerus, or 
even higher. This, however, is the largest 
artery which arises from the trunk at the 
bend of the arm. Scarcely has it arisen, when 
it sinks deep into the cavity that is occupied 
by the tendon of the biceps, the nerve, blood- 
vessels, and fat. It then bends near the in- 
terstice of the bones, under the pronator teres, 
radial flexor, palmaris longus, and sublimis, 
to the lunar side of the fore arm, proceeding 
gradually with many deflections between the 
sublimis, the profundis, and ulnar flexor, to 
the wrist. Passing over the wrist, it forms 
the superficial arch of the hand, which gives 
beautiful arteries to the lingers, affd'Tihally 
inosculates at the palm with the radial. The 
chief branch is, 
1. The common interosseal, rising at 
the higher extremity of the profundus, 
running on the interosseous ligament, 
between the flexor pollicis and profun- 
dus, toward the pronator quadratus. 
The radial artery, the smallest of the two 
branches which proceed from the division of 
the humeral. It runs down in a straight line 
upon the surface of the pronator, and gradu- 
ally inclines towards the radius, between the 
long supinator and radial flexus, resting on 
the flexor of the thumb. At the lower ex- 
tremity of the radius, where it is easily felt 
between the styliform process and the trape- 
zium, on the back of the hand, it bends under 
the abductor and extensor of the thumb, near 
tire first radial extensor; then penetrating the 
abductor, or semi-interosseus of the fore- 
finger, between the metacarpal hone of the 
fore-finger and thumb, bends, while there 
concealed, to the palm between the fibres of 
the adductor pollicis, and forms, in the hol- 
low of the hand, under the flexors, and above 
the interosseous muscles, the deep volar arch, 
in which it terminates. 
SECOND SUBDIVISION. 
Branches from the descending aorta. 
It appears, from the general description of 
the aorta, that, after the formation of the 
arch, it bends gradually behind the lungs to 
the left side of the vertebral column ; and ly- 
ing close upon this column, penetrates, in a 
straight line, behind the pleura, through the 
cavity or the thorax, to the muscular crura 
of the diaphragm, directing its course in the 
abdomen to the inferior lumbar vertebra 1 . 
Anatomists have therefore properly divided 
the descending aorta into the thoracic and 
ventral, whose limits are defined by the dia- 
phragm, which allows, by the separation of 
its crura, a convenient passage for the de- 
scending trunk. 
Distribution of the thoracic aorta. 
Through its whole descent, the thoracic 
aorta inclines to the left; though near the 
lesser or inferior diaphragm it. seems gradu- 
ally to approach the middle of the vertebra 1 . 
The numerous branches which it sends out, 
though not large, are yet worthy of notice. 
These are, the pericardiac, bronchial, oeso- 
phageal, and aorta, or inferior intercostal 
arteries. 
Distribution of the ventral aorta. 
The ventral or abdominal aorta, is the low- 
est part of the common trunk. It passes from 
the thorax, through the inferior muscle of the 
I diaphragm, to the right side of the oesophagus, 
| in a straight direction, inclining rather to the 
left, and proceeds gradually through the ab- 
domen upon the surface of the vertebral co- 
lumn to the fifth lumber vertebra, and to the 
thick ligament connecting the fourth and 
fifth. r i he inner or long crura of the dia- 
phragm, variously interwoven behind the 
oesophagus, separate anteriorly on the aorta, 
allowing a passage through which it descends, 
resting posteriorly on the vertebral column. 
This passage is considerably larger than the 
trunk, loose cellular substances, connecting 
the pleura and peritoneum, being interposed. 
The aorta at this place is separated from the 
vena cava by the left lobe of the liver, a part 
of the diaphragm, and a large quantity of cel- 
lular substance; but in the space between the 
kidneys and the liver, these two vessels ap- 
proach so near, that the margin of the artery 
is partly covered by the vein that afterwards 
sends some of its branches anteriorly across. 
The ventral aorta is divided at the verte- 
bra mentioned above, into two branches of 
equal size, forming an acute angle as they run 
forwards to the brim of the pelvis. These 
anatomists have called ilia communes, or 
common iliacs. The branches of the ventral 
aorta are best described in the order in which- 
they occur. 
1. The phrenic artery, right and left, 
very irregular in origin and division. 
Sometimes- a single trunk arising above 
the codiac, divides into the right and 
left phrenic: sometimes, again, and 
indeed most frequently,' the right rises 
from the coeliac, and the left irom the 
aorta ; while, at other times, they have 
been observed rising together, both from 
the cudiac, or both from the aorta. 
Sometimes the single trunk or common 
phrenic, being larger than usual, consti- 
tutes the fourth br..nch of the coeliac ; 
and then forms the superior coronary 
branch of the stomach. There aresome- 
tiuiesthree or four phrenic arteries, which, 
as soon as they arise, tend obliquely out- 
wards belore the crura of the diaphragm 
to die inferior margin of its tendinous 
ala. 1 ; and, while they here wind tortu- 
ously under the fleshy fibres, distribute 
various twigs, upwards, outwards, in- 
wards, and downwards. Bending at last 
to the external margin of the tendon, 
and passing between the muscular layers, 
they run forwards, and inosculate, upon 
the costal muscles, with the thoracic ves- 
sels and the artery of the opposite side. 
At the bend of the artery, however, they 
send a large branch to the posterior and 
interior portion of the diaphragm, as it 
rises from the ribs. 
II. The c uTtac artery, short, but of large 
diameter, rising between the aorta of the dia- 
phragm, above the eleventh dorsal vertebra, 
from the anterior part of the aorta, and at the 
superior margin of the pancreas, between the 
papillary lobule, or lobule of Spigelitis, and 
the left side of the lesser arch of the stomach. 
It then descends in a tortuous manner for- 
wards, and to the right, and running about 
the third of an inch, ultimately separates into 
three branches in such a manner, that the 
two on the right seem to arise from the com- 
mon base ; while the left is more distinct at 
its origin. These are, 
1. The superior coronary, or great left 
gastric,, or superior or left gastro-hepatic, 
03 
fe 
smaller than the other branches, if re- 
flected only to the stomach ; but almost 
equal in size to the splenic, it, as some- 
times happens, it sends a branch also to 
the liver. It appears sometimes to issue 
from the splenic, ascends to the left, and 
forwards to the cardia and lesser arch of 
the stomach; then bending downwards 
and to the right, reaches the margin of 
the stomach, where it distributes exten- 
sively its circuitous branches, forming a 
corona to both sides of the stomach. 
2. The hepatic. — This artery, which 
in adults is smaller than the splenic, but 
in children larger, rises from the right 
side of the coeliac, or, as sometimes hap- 
pens, from the superior mesenteric, when, 
turning upwards near the outer point of 
the lobule of Spigelius, it is concealed 
by the pancreas; then proceeding for- 
wards, upwards, and to the right, behind 
the right extremity of the stomach and 
duodenum, it observes the same obliquity 
as the lesser arch ; and after running an 
inch or an inch and a half, divides below 
the neck of the gall-bladder into the right 
transverse and left ascending hepatics ; 
entering at last, with the other hepatic 
vessels, the transverse fissure or fossa of 
the liver. Inclosed in the capsule of Glis- 
son, it occupies a middle space between 
the biliary ducts and the vend porta. 
3. The splenic.— While this artery 
runs along the upper surface of the pan- 
creas, and passes transversely to the de- 
pression of the spleen, it exhibits large 
and repeated Ilex ions upwards and down - 
wards, bending in a circular or spiral 
form. Approaching the substance of the 
spleen, it divides into many branches, 
which are equally tortuous ; and of those 
that sink into the spleen, some smaller 
ones return through the substance of the 
diaphragm or stomach. 
III. The superior mesenteric, the, largest 
of the abdominal or ventral branches, ■ rising 
between the crura ot the diaphragm, three or 
four lines below the cudiac, Irom the anterior 
part ot the aorta, and under the lower edge 
of the pancreas, proceeds between the gland 
and the inferior transverse flexion of the duo- 
denum. Passing over this portion of the in- 
testine, it bends to the right under the meso- 
colon, where, received near the vertebra into 
the folds of the mesentery, it first inclines to 
the lett and then to the right, where the whole 
artery, advancing to the right ilium, assumes 
the form of the Roman S, with the concave- 
side of its large curvature looking to tire right. 
After giving oft’ smaller branches, the trunk 
sends from its right side only two branches to 
the large intestines ; but from the left it gives 
a greater number of branches to the smaller 
intestines. 
These, from twelve to twenty, rise close to 
one another from the lett convex side of the 
superior mesenteric, distributing ramuli to the 
ileum and jejunum. Of these the superior 
are short and slender, the middle long and 
thick, the inferior shortest, and the last branch 
of all, as observed above, inosculates with the 
ileo-colic. Running near and parallel to each > 
other, they first proceed transversely ; then, 
rising between the layers of the mesentery, 
divide into smaller branches, which so. diverge, 
that in whatever direction they go, they are 
soon alter divided into two. These branches, 
as they meet, form various arches, from whose • 
