THE INFERIOR VENA CAVA AND ITS TRIBUTARIES. S49 
the inferior phrenic arteries are formed by tributaries which issue from the sub- 
stance of the diaphragm. The right veim terminates in the upper part of the 
inferior vena cava. The left veins pass behind the cesophagus, and usually end in 
the left suprarenal vein. 
Suprarenal Veins.—A single suprarenal vein (v. suprarenalis) issues from the 
hilus on the anterior surface of each suprarenal body; the right vein terminates 
in the inferior vena cava; the left usually ends in the left renal vein, but sometimes 
also opens directly into the inferior vena cava. 
Renal Veins (vy. renales).—Kach renal vein is formed by the union of five or six 
tributaries which issue from the hilus of the kidney, where the -y lie in front of the 
corresponding arteries. 
The right renal vein is about one inch long; it passes behind the second part of 
the duodenwn, and terminates in the right side of the inferior vena caya. 
The left renal vein crosses in front of the left psoas, the left crus of the diaphragm, 
and the aorta immediately below the superior mesenteric artery. It lies behind 
the pancreas and the fourth part of the duodenum, and, running above the third 
part of the duodenum, terminates in the left side of the inferior vena cava. The 
left spermatic or ovarian vein, according to the sex, and almost invariably the left 
suprarenal vein, open into it. 
Lumbar Veins (vv. lumbales).— There are usually tour lumbar veins on 
each side, one with each lumbar artery; the vein with the subcostal artery is not 
included in this number. The lumbar veins are formed by the union of anterior 
and posterior trunks between the transverse processes of the vertebrae. ~The 
anterior tributaries commence in the lateral walls of the abdominal cavity, where 
they communicate with the superior and deep epigastric veins. The posterior 
tributaries issue from the muscles of the back in the lumbar region, and receive 
tributaries from the spinal plexuses. The main stems pass forwards on the bodies 
of the vertebrve; on each side they run under the psoas muscle, whilst those 
of the left side also pass behind the aorta. They terminate in the posterior 
part of the inferior vena cava. Not uncommonly the corresponding veins of 
opposite sides unite together to form a single trunk which enters the back of the 
inferior vena cava. All the lumbar veins of each side are united together by a 
longitudinal anastomosing vessel, the ascending lumbar vein, which passes upwards 
in front of the transverse processes of the lumbar vertebrae, and usually ends 
above in an azygos vein, whilst below it connects the lumbar veins with the ilio- 
lumbar and lateral sacral veins. 
Spermatic Veins (vv. spermatice).—The spermatic veims on each side issue 
from the testicle and epididymis and form a plexus, the pampiniform plexus. The 
plexus forms part of the spermatic cord, and consists of from eight to ten veins, 
most of which he in front of the vas deferens; it passes. upwards in the inguinal 
canal, and, near the internal abdominal ring, terminates in two main trunks which 
ascend with the corresponding spermatic artery for some distance, receiving 
tributaries from the ureter, and on the left side from the iliac and pelvi 1c colon: 
ultimately the two veins unite together and a single terminal vein is formed. The 
terminal spermatic vein on the right side opens into the inferior vena cava, that 
on the left side into the left renal vein. The left spermatic veins are longer than 
the right, the left testicle bemg lower than the right, and the termination in the 
left at vein being at a higher level than the termination of the right vein in the 
inferior vena cava. The spermatic veins on each side lie upon the psoas muscle 
and the ureter. They are covered by peritoneum, and they are crossed on the 
right side by the termination of the ileum and the third part of the duodenum, 
and on the left side by the ihae colon. They are provided with valves both 
in their course and at their terminations, but occasionally the valve at the orifice 
of the left spermatic vein is absent. 
The ovarian veins (vv. ovarice), on each side, issue from the hilus on the 
anterior border of the ovary. They pass between the layers of the broad ligament, 
where they anastomose freely and form the pampiniform plexus, which extends 
outwards towards the brim of the pelvis. From the plexus two veins are formed 
which accompany the corresponding ovarian artery ; they pass in front of the external 
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