218 CIRCULATORY SYSTEM. 



2. The circumjlex vein of tlie ileum, after ramifying with its ar- 

 tery, 3. At their point of junction, the middle sacral vein, an 

 azygos vessel of small size, corresponding to the artery bearing 

 the same name. 



The Internal Iliac Vein 



Is extremely short — in fact, it is nothing more than the root 

 common to the two venous trunks by which it is said to be formed, 

 \\z. the iscliiatic,^nd lateral sacral veins. Its situation is at the 

 brim of the pelvis, a little outwardly to the sacro-iliac symphysis. 



The iscHiATic vein, lying against the side of the pelvic 

 cavity, midway between the external iliac and lateral sacral veins, 

 consists of a short but bulky trunk, and of a collection of large 

 branches uniting to form it, at the upper 0])ening of the great 

 sacro-sciatic notch. These branches may be distinguished into an 

 internal and an external set. The internal comprise veins com- 

 ing from the bladder, anus, perineum, and, in the male, from the 

 bulb and prostates — in the female, from the vulva and corpora 

 cavernosa vagince. The external consist of veins coming princi- 

 pally from the gluteal and obturator muscles. 



The lateral sacral vein originally comes from the tail, 

 springing there from the combination of two or three slender coc- 

 cygeal veins: it runs forward along the side of the sacrum, re- 

 ceiving other veins in its course, viz. 1. Perineal veins, a collection 

 of small branches coming from the posterior parts of the thigh, 

 gluteal muscles, perineum, and anus. 2. Sacrospinal branches, 

 small veins issuing from the spinal canal, through the internal 

 sacral foramina. 



The External Iliac Vein 



Is found running along the inner and upper side of the extei^ 

 nal iliac artery, taking all the way precisely the same course as 

 the artery. It extends from its junction with the posterior vena 

 cava to the place where it leaves, in company with tiie artery, the 

 brim of the pelvis; the vein after that hecom\ug femoral. As it 

 depaits from the cavity of the belly, this vessel receives the 



Inguinal VEIN, one of rather large size coming from the 

 groin, which owes its (brmation to a considerable branch emerg- 

 ing from the muscles of the thigh, and a superficial or cutaneous 

 abdominal vein ; which latter runs in a serpentine manner along 

 the abdomen, after taking its rise as far forward as the cartilages 

 of the ribs, where its branches form communications with the cu- 

 taneous veins of the thorax : it is a very conspicuous vessel in 

 milch cows, and is vulgarly denominated the milk vein. 



