VASCULAR SYSTEM. 713 
The right ventricle is not so muscular as the left, 
which it partly surrounds. By its contraction the blood 
is driven into the pulmonary trunk, whose orifice is 
guarded by three semilunar valves. During contraction 
the tricuspid valves are pressed together, so that no 
regurgitation into the right auricle can take place. 
The pulmonary trunk - 
divides into two pulmonary a 
arteries, which branch | into 
capillaries on the walls of the 
lungs. There the red biood 
corpuscles gain oxygen, and 
the blood is freed from much 
Fic. 391.—Circulatory system of 
the rabbit. 
(a) Letters to right— 
e.c. External carotid. 
z.c. Internal carotid. 
ej. External jugular. 
scl.a, Subclavian artery. 
scl.y. Subclavian vein. 
g.a. Pulmonary artery (cut short). 
p.v. Pulmonary vein. 
L.A. Left auricle. 
L.V. Left ventricle. 
d.ao. Dorsal aorta. 
hv. Hepatic veins. 
c. Ceeliac artery. 
a.m, Anterior mesenteric, 
5.7.6. Suprarenal body. 
ir.a. Left renal artery. 
Zr.v. Left renal vein. 
&. Kidney. 
p.m. Posterior mesenteric artery 
(inadvertently shown as if 
paired). 
spm. Spermatic arteries and veins. 
c.zl.a. Common iliac artery. 
() Tetters to left— 
pf. and a,f. Posterior and anterior 
facial. 
ej. External jugular vein, 
z.j. Internal jugular. 
R.Sct. Right subclavian artery. 
S.V.C. Superior vena cava. 
R.A. Right auricle. : 
R.V. Right ventricle. 
J.V.C. Inferior vena cava, 
v.r.a. Right renal artery. 
yr.v. Right renal vein. 
s.7.6, Suprarenal body. 
sfm. Spermatic arteries and veins, 
2.2, Ilio-lumbar vein. 
fv. Femoral vein. 
1.21.v. Internal iliac veins, 
