THE INTERNAL ILIAC ARTERY 



573 



ventralis) runs outward in the intertransverse space, passes between the transversus 

 and ol)Hquus internus abdominis, gives branches to these muscles, and ends in the 

 obUciuus externus, the pannicuhis, and the skin of the flank. 



THE INTERNAL ILIAC ARTERY 



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

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

 at an angle of al)out GO degrees, and each jiasses backward under the wing of the 



Perineal arlcrij 



Pcrimid nvrris 

 Internnl pitdic 



artery 

 Dorsal nerve of 



penis 



Si I rro-coceygeus inferior 

 lu rlo-coceygcus 



Sphincter ani externus 



Retractor ani 



Fig. -152. — Di- ■ . i. v of Perineum of Horse (Male). 



1, Bulbo-urethral (Cowper's) gland; 2, transversus perinei muscle (?); 3, isehio-urethral muscle; 4, retractor penis 



muscle; S, bulbo-cavernosus muscle. (After Schmaltz, Atlas d. Anat. d. Pferdes.) 



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

 divides a little above the psoas tubercle into iliaco-femoral and obturator arteries. 

 The chief branches are as follows: 



1. The last pair of lumbar arteries pass up through the foramina at the 

 junction of the last lumbar vertebra and the sacrum. 



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

 internal iliac. It passes Imckward and somewhat downw^ard, at first along the 

 iliac head of the obturator internus, then above the superior ischiatic spine on the 

 inner surface of the sacro-sciatic ligament, perforates the latter and runs for a 

 variable distance in its substance or on its external face. It then re-enters the 

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



