DISSECTION OF THE PELVIS. 355 



In the female the internal pndic terminates in hemorrhoidal, vulvar, 

 and bulbous branches ; and, instead of the vesico-prostatic, it gives off 

 the vaginal artery, which is expended in the bladder, vagina, and cervix 

 uteri, anastomosing with branches of the uterine artery. 



The Umbilical or Hypogastric Artery. In the adult (Plate 46) 

 this is a comparatively small vessel arising from the internal pudic 

 near its root. It is pervious only in the first few inches of its course, 

 giving off a few twigs to the bladder, and being then continued as 

 a solid cord at the free edge of the lateral ligament of the bladder. 

 In the foetus, however, it is of great size, and carries the foetal blood 

 to the placenta to be purified. 



The Internal Pudic Vein runs in company with the artery. It 

 receives branches corresponding to those of the artery, and terminates 

 in the internal iliac vein. 



The Pudic Nerve is derived from the 3rd sacral. Descending on the 

 inner surface of the sacro-sciatic ligament, it crosses the internal pudic 

 vessels superficially at the small sacro-sciatic foramen. Here it turns 

 slightly inwards, and disappears beneath the ischio-urethral muscle. 

 Having gained the lower face of the urethra, it turns round the ischial 

 arch, and is continued as the dorsal nerve of the penis. Before leaving 

 the pelvis it detaches a perinceo-anal branch, which gives twigs to the 

 muscles of the urethra and penis, and hsemorrhoidal branches that pass 

 upwards on the rectum to reach the anus, some of them appearing 

 to terminate in the sphincter. These latter branches are crossed by 

 descending branches from the haemorrhoidal nerve. 



The lower posterior gluteal nerve (Plate 16) gives fibres to both the 

 trunk of the pudic nerve and its perinaeo-anal branch, and in some 

 cases the latter derives the majority of its fibres from this source. 



In the female the pudic nerve terminates in branches to the labia, 

 clitoris, and constrictor muscles of the vulva. 



The Hemorrhoidal Nerve is derived mainly from the 4th sacral. 

 It descends on the inner face of the sacro-sciatic ligament and (for a 

 short distance) compressor coccygis muscle. It supplies a twig to 

 that muscle, and then penetrates it, or emerges between it and the 

 retractor ani. It then divides into branches for the retractor and 

 sphincter muscles of the anus, and for the skin of the perinseum. 



The Retractor Ani. This muscle is described with the perinseum 

 (page 284), but it is here exposed in the whole of its extent. 



The Compressor Coccygis (Fig. 48) arises from the inner surface of 

 the sacro-sciatic ligament, over the superior ischiatic spine. Passing 

 backwards and upwards, it is inserted into the last sacral and first 

 two coccygeal vertebrae. By its inner face it is related to the rectum, 

 except close to its insertion, where the edge of the depressor of the tail 

 intervenes. 



