THE ARTERIES. 301 
also sends branches onto the dorsum of the hand at the sides 
of the fourth metacarpal. Branches pass from these proximad 
to the wrist. 
B. AORTA ABDOMINALIS. THE ABDOMINAL AORTA.— 
The abdominal aorta emerges into the abdomen from between 
the crura of the diaphragm, at about the 
level of the second lumbar vertebra. It 
passes caudad along the dorsal middle 
line, lying to the left of the inferior vena 
cava. It gives off parietal branches to 
the body wall, and visceral branches to 
the viscera, and ventrad of the first sacral 
vertebra it gives off two large branches on 
each side, the external iliac (Fig. 126, R) 
and the hypogastric (Fig. 126, /)—a very 
small median vessel, the sacralis media 
(Fig. 126, 0), continuing the course of the pup parmar ARcH AND 
aorta and passing into the tail. ifs BRANCHES IN THE 
Z PALM OF THE HAND. 
The aorta gives off the following 
: 7 The interosseous mus- 
branches: A. celiaca; A. mesenterica cles have been removed, 
‘ t t the t 
superior; Aa. adrenolumbales; Aa. re- and fourth digits, ey M 
nales; A. mesenterica inferior; Aa. ilio- oer a gel ee 
. , m. interossel 0: are 
lumbales; Aa. lumbales (seven pairs); oy fear digits; 4, M. 
Aa. iliace externe ; Aa. hypogastrice. adductor pollicis; 5, M. 
‘ 4 : flexor brevis pollicis. a, 
A. A. celiaca (Fig. 125).—The coeliac termination of radial artery; 
: ‘ : : 6, palmar arch; ¢, A. prin- 
artery is a large branch which is given off cans pallicly al iediatee dt 
from the aorta one centimeter or less Aa. interosse; ¢, muscu- 
‘i 2 , lar branches of th ; 
caudad of the opening in the diaphragm. + Kodiiate aecrpe 
It passes directly ventrad about three or mar branch of ulnar nerve. 
four centimeters, then divides, usually at once, into three 
branches. The most cranial of these is the hepatic (d), the 
next is the gastrica sinistra (¢), while the third and largest, 
seeming to form a continuation of the cceliac, is the splenic (/) 
(A. lienalis). The cceliac artery may give rise also, before its 
division, to the two phrenic arteries (which, however, usually 
arise from the adrenolumbales), and either before or at the point 
of division to one or two small Aa. ventriculi dorsales, which, 
however, frequently arise from the gastrica sinistra. 
