262 PRACTICAL ANATOMY. 



gluteal, sciatic, internal pudic, obturator, and other veins 

 which accompany the branches of the internal iliac 

 artery. It also drains the venous plexuses of the pelvis, 

 as the prostatic and haemorrhoidal. In the female it 

 drains the vesical, vaginal, uterine, and rectal plexuses. 

 The haemorrhoidal plexus is formed by the anastomoses 

 of the superior middle and inferior haBmorrhoidal veins. 

 This plexus is also drained by the inferior and superior 

 mesenteric veins, which terminate in the portal vein. 

 The dorsal vein of the penis consists of two branches 

 which drain the blood from the organ. These two 

 branches unite, form a single trunk, which pierces the 

 suspensory ligament of the penis and the triangular liga- 

 ment, and empties into the prostatic plexus. The pros- 

 tatic plexus surrounds the neck of the bladder. The 

 vaginal plexus, largely composed of erectile tissue, sur- 

 rounds the lower portion of the vagina. The uterine 

 plexuses are at the superior angles and sides of the 

 uterus ; they drain the uterine sinuses. 



The common iliac veins are formed by the union of 

 the external and internal iliacs, and unite to the right of 

 the fourth lumbar vertebra to form the ascending vena 

 cava. The vena cava ascendens passes upward along 

 the right side of the vertebral column, lies in the fissure 

 in the posterior border of the liver, passes through the 

 quadrate opening of the diaphragm, and enters the pos- 

 terior and inferior portion of the right auricle. Its 

 tributaries are the lumbar veins, the right spermatic, 

 renal, supra-renal, phrenic, and hepatic. The lumbar 

 consists of three or four pairs of veins that drain the 

 structures in the lumbar regions. The spermatic veins 

 arise in the spermatic or pampiniform plexus, at the pos- 

 terior part of the testicle ; they pass through the ingui- 

 nal canal ; the right empties into the ascending vena 



