Veins of Pelvis 377 



of its artery. The external iliac vein joins the internal opposite the 

 ala of the sacrum to form the common iliac. 



Because of the general inclination of the veins towards the right, 

 the right external iliac vein in its ascent gradually sinks beneath the 

 corresponding artery ; whereas, on the left side, the vein keeps always 

 along the inner side. 



The external iliac vein receives two tributaries just above Poupart's 

 ligament, corresponding to the branches of the artery, namely, the 

 deep epigastric and the deep circumflex iliac veins. The latter branch, 

 having come from the region of the iliac crest, reaches the iliac vein 

 by passing over the external iliac artery. 



The internal iliac vein is formed by the confluence of the vense 

 comites of the branches of the internal iliac artery ; though, of course, 

 the single umbilical vein, which corresponds to the two hypogastric 

 arteries, has no concern therewith. These venae comites form a free 

 anastomosis about the vagina, uterus, rectum, bladder, and prostate ; 

 and the haemorrhoidal branches have an important communication 

 with the inferior mesenteric vein, that is, with the beginning of the 

 vena portas. 



*R& prostatic plexus of veins is placed between the capsule of the 

 gland and the investment of the recto-vesical fascia. It is in free 

 communication with the vesical and the lower haemorrhoidal veins, 

 and receives anteriorly the dorsal vein of the penis, which enters it 

 through the triangular ligament (p. 413). The vesico-prostatic veins 

 are often much dilated ; they are liable to imflammation after lithotomy, 

 and they sometimes contain calcareous concretions phleboliths. 



The common iliac veins are formed opposite the ala of the sacrum, 

 by the confluence of the external and internal iliac veins ; and, passing 

 upwards and to the right, they unite at the right side of the fifth 

 lumbar vertebra to form the inferior vena cava. 



The common iliac veins lie, at their commencement, to the inner, 

 the median, side of their respective arteries, and, to reach the right side 

 of the fifth lumbar vertebra, each must pass beneath the right common 

 iliac artery. Thus, in its ascent, the left vein is always on the inner 

 (right) side of the left artery, and it ultimately crosses the right artery 

 on a posterior plane, of course. (See Rule, p. 368.) The beginning 

 of the right vein is slightly to the inner side of the right common iliac 

 artery, and, to reach the right side of the fifth lumbar vertebra, it has 

 to cross the right common iliac artery on a posterior plane. In its 

 ascent, the right vein lies, for the most part, behind, and, ultimately, 

 as it swells out into the beginning of the vena cava, a little to the 

 outer side of its artery. 



The student will best understand the arrangement of the iliac 

 arteries and veins by making an outline sketch of the aorta, the com- 

 mon, external, and internal iliac arteries, placing a figure 4 at the 

 division of the aorta representing the fourth lumbar vertebra and a 



