THE DEEP VEINS OF THE LOWER EXTREMITY 



747 



the artery; they enter the pelvis through the great sacrosciatic foramen, above 

 the Pyriformis, and frequently unite before ending in the internal iliac vein. 



2. The sciatic veins (vv. glutaeae inferior es), or venae comites of the sciatic 

 artery, begin on the upper part of the back of the thigh, where they anastomose 

 with the internal circumflex and first perforating veins. They enter the pelvis 

 through the lower part of the sacrosciatic foramen and join to form a single stem 

 which opens into the lower part of the internal iliac vein. 



3. The internal pudic veins (vv. pudendae internae) are the venae comites of the 

 internal pudic artery. They commence in the veins which issue from the corpus 

 cavernosum, accompany the internal pudic artery, and unite to form a single 

 vessel, which ends in the internal iliac vein. They receive the veins from the 

 bulb of the urethra, the superficial perineal, and the inferior hemorrhoidal veins 

 (vv. hemorrhoidales inferiores). The deep dorsal vein of the penis communicates 

 with the internal pudic veins, but ends mainly in the vesicoprostatic venous plexus. 



CIRCUMFLEX 

 ILIAC 



DEEP 

 EPIGASTRIC 



LATERAL 

 SACRAL 



Ml DO' 

 SACRAL 



FIG. 522. The iliac veins. (Poirier and Charpy.) 



4. The obturator vein (v. obturatoria) begins in the upper portion of the adductor 

 ?gion of the thigh and enters the pelvis through the anterior part of the obturator 



toramen. It runs backward and upward on the lateral wall of the pelvis below 

 the obturator artery, and then passes between the ureter and the internal iliac 

 irtery, to end in the internal iliac vein. 



5. The lateral sacral veins (vv. sacrales laterales) accompany the lateral sacral 

 arteries on the anterior surface of the sacrum and terminate in the internal iliac 

 vein. 



6. The middle hemorrhoidal vein (v. hemorrhoidalis media} takes origin in the 

 hemorrhoidal plexus and receives tributaries from the bladder, prostate gland, 

 and seminal vesicle; it runs outward on the pelvic surface of the Levator ani to 

 end in the internal iliac vein. 



