294 THE VASCULAR .SYSTEMS 



THE VEINS OF THE PELVIS 



The internal iliac vein accompanies the artery, lying behind 

 and to its inner side, to join the external at the base of the 

 sacrum, forming the common iliac. Its tributaries correspond 

 to the branches of the artery in a general way. Thus it receives 

 the following tributaries: 



The gluteal, sciatic, and the obturator; the lateral sacral, 

 which form a plexus on the sacrum and open into the internal 

 iliac at several points; the internal pudic, which receives branches 

 corresponding to the perineal branches of the artery and com- 

 mences as the vein of the corpus cavernosuni. 



The dorsal vein of the penis, at first two veins, these uniting 

 into one, which runs back between the two dorsal arteries 

 in a median groove, passes below the subpubic ligament and 

 divides into two veins, joining each side of the prostatic plexus, 

 and each division communicating with the obturator and 

 pudic veins of each side. 



The visceral veins are larger than the arteries, and communi- 

 cate freely with one another, so as to form a series of plexuses, 

 as follows: 



The prostatic plexus, continuous above with the vesical 

 plexus, is formed by the dorsal vein of the penis and branches 

 from the prostate and its vicinity. It communicates with the 

 radicles of the pudic vein. This plexus has its analogue in 

 the female around the urethra, which receives the dorsal vein 

 of the clitoris. 



The vesical plexus extends over the body and base of the 

 bladder, and communicates with the prostatic and hemorrhoidal 

 plexuses; vaginal in the female. 



The hemorrhoidal plexus, in the wall of the lower rectum, 

 beneath the mucous coat, sends out superior, middle, and 

 inferior hemorrhoidal veins, which follow the corresponding 

 arteries, and communicate freely with the other plexuses. 



The vaginal plexus surrounds the lower part of the vagina, 

 and communicates with the vesical and hemorrhoidal plexuses, 

 and the uterine plexus empties into the ovarian Vein. 



