THE COMMON ILIAC VEINS. 983 



Venae Testiculares. The testicular veins, on each side, issue from the testis 

 and epididymis and form a plexus, the pampiniform plexus. The plexus is one 

 of the constituents of the spermatic cord, and consists of from eight to ten veins, 

 most of which lie anterior to the ductus deferens ; it passes upwards through the 

 scrotum and inguinal canal, and, near the abdominal inguinal ring, terminates in 

 two main trunks which ascend, with the corresponding testicular artery, for some 

 distance, receiving tributaries from the ureter; ultimately the two veins unite 

 together and a single terminal vein is formed. The terminal testicular vein on 

 the right side opens into the inferior vena cava, that on the left side into the left 

 renal vein. The left testicular vein is longer than the right, the left testis being 

 lower than the right, and the termination in the left renal vein being at a higher 

 level than the termination of the right vein in the inferior vena cava. The 

 testicular veins, on each side, lie anterior to the psoas major 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 iliac colon and the lower part of the pancreas. They are provided with 

 valves, one of which usually lies at the terminations of each vein, but, occasionally, 

 the valve at the orifice of the left testicular vein is absent. 



Vense Ovaricae. The ovarian veins, on each side, issue from the hilum in 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, 

 laterally, towards the upper margin of the pelvis minor. From the plexus two 

 veins issue which accompany the corresponding ovarian artery ; they pass anterior 

 to the external iliac artery, and then upwards, behind the peritoneum and anterior 

 to the psoas major muscle and ureter. The veins of the right side, like the corre- 

 sponding testicular veins, also pass behind the termination of the ileum and the 

 third part of the duodenum ; whilst the left veins, near the margin of the pelvis 

 minor, pass behind the commencement of the pelvic colon. 



The two veins on each side ultimately fuse together to form a single terminal 

 vein which ends, on the right side in the inferior vena cava, and on the left side in 

 the left renal vein. 



VEN.E ILIAC^E COMMUNES. 



The common iliac veins (Figs. 777 and 792), right and left, are formed by the 

 union of the corresponding external iliac and hypogastric veins. Each commences 

 at the superior aperture of the pelvis minor, immediately posterior to the upper 

 part of the hypogastric artery of its own side, and both vessels pass upwards to 

 the right side of the body of the fifth lumbar vertebra, at the upper part of 

 which, posterior and lateral to the right common iliac artery, they unite together 

 to form the inferior vena cava. 



The right common iliac vein is much shorter than the left ; it passes anterior 

 to the obturator nerve and the ilio-lumbar artery, and at first posterior and then 

 somewhat to the lateral side of the corresponding common iliac artery. 



The left common iliac vein is much longer than the right, and is also placed 

 more obliquely. It passes upwards and to the right, anterior to the body of the fifth 

 lumbar vertebra, and the middle sacral artery. For some distance it runs along 

 the medial side of the left common iliac artery, and then passes posterior to the 

 right common iliac artery. It also passes posterior to the mesentery of the pelvic 

 colon and the superior hsemorrhoidal vessels. 



Tributaries. Each common iliac vein receives the corresponding external iliac, 

 hypogastric and ilio-lumbar veins. The left common iliac vein receives, in addition, 

 the middle sacral vein. 



The ilio-lumbar veins receive tributaries from the iliac fossa, from the lower parts of 

 the vertebral muscles, and from the vertebral canal. There is a single vein on each side 

 which accompanies the corresponding artery. It passes posterior to the psoas major 

 muscle and terminates in the corresponding common iliac vein. 



Vena Sacralis Media. The venae comites of the middle sacral artery commence by 

 the union of tributaries which issue from the venous plexus in front of the sacrum, 



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