THE HYPOGASTRIC VEIN 



679 



THE COMMON ILIAC VEINS 



The common iliac veins [vv. iliacse communes], (fig. 536) are formed opposite 

 the sacro-iliac articulation by the confluence of the external iliac and hypo- 

 gastric (internal iliac) veins. They converge as they ascend, and unite oppo- 

 site the upper border of the fifth lumbar vertebra and a little to the right of the 

 median line to form the vena cava inferior. 



Fig. 534. — The Superior Mesenteric Vein. 

 (The colon is turned up, and the small intestines are drawn over to the left side.) 



Middle colic 

 artery 

 Inferior pancre- 

 atico-duodena. 

 artery 



— Left colic artery 

 Superior mes- 

 enteric artery 

 and vein 



Jejunum 



Ileo-colic artery 



The right vein, shorter and more vertical in direction than the left, passes obliquely behind 

 the right common iliac artery to its lateral side, where it is joined by the left common iliac vein. 



The left vein lies to the medial side of the left common iliac artery, and, after crossing in 

 front of the promontory of the sacrum and the fifth lumbar vertebra below the bifurcation of 

 the aorta, passes beneath the right common iliac artery to join the right vein and form the 

 vena cava inferior. The left vein may contain an imperfect valve. 



Tributary. — -The ilio-lumbar veins may enter the lower part of the common 

 iliac, or open into the hypogastric vein. The left vein receives the middle sacral 

 vein. 



The middle sacral vein [v. sacralis media] opens usually as a single trunk 

 into the left common liiac vein. The venae comitantes which form it ascend on 

 either side of the middle sacral artery in front of the sacrum. They communicate 

 with the lateral sacral veins, forming the anterior sacral plexus [plexus sacralis 

 anterior] which receives the sacral intervertebral veins, and anastomoses freely 

 with the neighbouring lumbar and pelvic veins. Below, the middle sacral veins 

 communicate with the hsemorrhoidal veins. 



THE HYPOGASTRIC VEIN 



The hypogastric (internal iliac) vein [v. hypogastrica] (fig. 536) is formed by 

 the confluence of the veins (except the umbilical) corresponding to the branches 



