618 



THE BLOOD-VASCULAR SYSTEM OF THE OX 



The posterior mesenteric artery arises from the aorta near its termination. It 

 is small and su]i]ili('S branches to the terminal part of the colon and to the rectum. 



The renal arteries arise from the aorta close together. The right one passes 

 outward and forward across the dorsal face of the posterior vena cava to the hilus 

 of the kidney. The left one runs backward, but necessarily varies in direction in 

 conformity with the position of the kidney {q. v.). 



The spermatic arteries resemble those of the horse. 



The utero-ovarian arteries are small. 



The five pairs of lumbar arteries derived from the aorta are distributed much 

 as in the horse. The sixth usually comes from the internal iliac artery. 



The middle sacral artery is a vessel about 5 mm. in diameter which continues 



Fig. 475. — Pelvic Arteries of Cow. 

 Part of the right wall of the uteiu.s and vagina is removed and the cervix uteri is shown in sagittal section. 

 <i, .\orta; h, utero-ovarian artery; 6', ovarian, and 6", uterine branch of h; c, external iliac artery; d, right internal 

 iliac artery; e, common trunk of umbilical artery (e') and middle uterine artery (/); g, ilio-lumbar artery; h, 

 anterior gluteal arteries; (', middle hiemorrhoidal artery; k. posterior uterine artery; /, perineal artery; 7>i, posterior 

 gluteal artery; n, obturator arteries; o, artery of clitoris; ;>, jjosterior mesenteric artery; r, anterior ha>mor- 

 rhoidal artery; s, middle .sacral artery; /, ovary; 2, ajjjjarent body of uterus, really apposed horns; 2', cornu; 

 S, vagina; 4, cervix uteri; 4', vaginal part of uterus (os uteri); 6, 6' , broad ligaments, large part of right one re- 

 moved; 6, urinary bladder; 7 , rectum; 8, sacrum; 9, symjihysis pelvis. (After Zieger.) 



the aorta. It arises from the dorsal face of the aorta at the angle of divergence of 

 the internal iliacs, runs backward on the pelvic surface of the sacrum a little to the 

 left of the median line, and is continued as the middle coccygeal artery. It gives 

 off small collateral branches to the spinal cord and the muscles of the tail and the 

 lateral coccygeal arteries. The latter may have a common trunk of origin, and 

 each divides into dorsal and ventral branches. The middle coccygeal artery runs 

 through the ventral (luemal) arches of tiie coccygeal vertebra'. The coccygeal 

 arteries are connected at i)retty regular intervals by segmental anastomoses. 



The internal iliac arteries are much longer than in the horse. Each passes 

 backward on the sacro-sciatic ligament and divides about the middle of the pelvic 

 wall into posterior gluteal and internal pudic branches. The chief differences in 

 its distribution are : (1) A large trunk gives origin to the umbilical and middle 



