qo6 



HUMAN ANATOMY. 



2. The Lateral Sacral Veins. — The lateral sacral veins (y\. sacrales laterales) 

 are usually double, and pass upward with their arteries upon the anterior surface 

 of the sacrum just medial to the anterior sacral foramina, and open above either 

 directly into the internal iliacs or into the gluteal \eins. As they pass each sacral 

 foramen they receive tributaries from the internal spinal plexuses, and opposite each 

 sacral vertebra are connected by transverse branches with the middle sacral veins, 

 these anastomoses forming the anterior sacral plexus. 



2, The Ilio-Lumbar Vein. — The ilio-lumbar vein (v. iliolunibalis) follows 

 the course of the corresponding artery and its branches and is richly supplied with 



Fig. 767. 



Aorta 



Vena cava inferior 



Genito-crural ner\'e 



Inter!;al iliac veiu 



Anterior superi*ir 



spine of ilium 



Obturator nerie 

 External iliac 



artery and veiu 

 Superior gluteal veiu 



Right and left common iliac arteries 

 Left common iliac vein 



Internal iliac vein 



Lateral sacral vein 



Sup. and deep layers of 

 triangular ligament 



Ischio-cavemosus muscle, 

 cut edge- 



Cowper's gland 



Bulbo-cavemosus 



muscle, cut edge 



Superior 



hemorrhoidal vein 



Lateral sacral vein 



Sciatic vein 



Internal pudic vein 



Vesical veins converg- 

 ing to a single tributary 

 of internal iliac vein 



Tributaries of internal 

 iliac from vesical 

 plexus 



Middle hemorrhoidal vein 



\'esico-prostatic plexus 



I'rostate 



Superficial anal sphincter. «ith 

 ^ enous plexus tributary to 

 inferior hemorrhoidal veins 



Anus 



Transverse perineal muscle 



Bulb of corpus spongiosum 



Veins of pelvis, viewed from left side. 



valves. Its lumbar tributarv receives some of the lower intervertebral veins and 

 occasionally the list lumbar, and anastomoses with the lower portion of the ascending 

 lumbar vein. The iliac tributary, which begins over the crest of the ilium and in 

 the substance of the iliacus muscle, makes anastomoses with tributaries of the deep 

 circumflex iliac vein and thus establishes an important collateral venous path between 

 the external, and internal iliacs. 



The main stem of the vein is a single trunk which, opens into the internal iliac 

 or occasionally into the common iliac. 



4. The Sciatic Vein.— The sciatic vein (v. glutaca inferior) of either side of the 

 body has essentially the same course as the corresponding artery. Its extrapelvic 



