THE INTERNAL ILIAC ARTERY 



669 



and obliquus internus abdominis, gives branches to tiiesc muscles, and ends in the 

 obliquus externus, the cutaneus, and the skin of the flanli. 



THE INTERNAL ILIAC ARTERY 

 The internal iliac or hypogastric arteries (Aa. hypogastrics) result from the 

 bifurcation of the aorta under the fifth or sixth lumbar vertebra. They diverge 

 at an angle of about 60 degrees, and each passes backward under the wing of the 

 sacrum, then inclines downward on the pelvic surface of the shaft of the ilium, 

 along the ventral border of the iliac head of the obturator internus, and divides a 



Coccygcus muscle 

 Annl hjinph glands 

 liranih of posterior gluteal 



mil I II 

 l'ii--l(ii 



liwmorrhoidal 



iiirm 



Vuhar branch of 



/iiiilic nerve 



I iilrriud pudic 

 artery 



Branch of pu- 

 dic nerve to 

 clitoris 



Obturator artery 



Fig. 578. — Dissection of Pehineum of Mare. 

 1, Sacro-coccygeus dorsalis; i?, sacro-coccygeus lateralis: 3, intertransversales; 4> sacro-coccygeus ventralis; J, 

 recto-coccygeus; 6, sphincter ani externus; 6', branch connecting sphincter ani with constrictor vulv£e; 7, vestibular 

 bulb; 5, tuber ischii; 6*, sacro-sciatic ligament. (After Schmaltz, Atlas d. Anat. d. Pferdes.) 



little (ca. 2 cm.) above the psoas tubercle into iliaco-femoral and obturator arteries. 

 The chief branches are as follows: 



1. The last pair of Ixunbar arteries pass up through the foramina at the junc- 

 tion of the last lumbar vertebra and the sacrum and are distributed as already 

 described. 



2. The internal pudic artery (A. pudenda interna) arises near the origin of the 

 internal iliac. It passes backward and somewhat downward, at first along the 

 ventral border of the iliac head of the obturator internus, then above the superior 

 ischiatic spine on the deep surface of the sacro-sciatic ligament, perforates the latter 

 and runs for a variable distance in its substance or on its lateral face. It then re- 

 enters the pelvic cavity, passes backward on the retractor ani to the ischial arch, 

 and divides into the perineal artery and the artery of the bulb in the male, perineal 

 and artery of the clitoris in the female. It is accompanied posteriorly by the 

 pudic nerve. Its chief branches are as follows: 



