242 



use on 

 rectum. 



Arteries of 

 the space. 



Pudic 

 artery: 



course ; 



posterior 

 part in 

 fossa ; 



depth and 

 relations. 



Branches : 



Inferior 

 hemorrhoi- 



dal. 



Muscular 

 offsets. 



Veins. 



Nerves of 

 the space. 



Pudic nerve 

 divides into 

 three parts : 



inferior 



haemorrhoi- 



dal; 



perineal ; 



DISSECTION OF THE PERINEUM. 



pelvic aspect of the muscle is the recto-vesical fascia. Along the 

 hinder border is placed the coccygeus. 



Action. It compresses the lower part of the rectum during the 

 act of defecation. 



This muscle will be more fully seen and examined in the dissection 

 of the pelvis (p. 382). 



ARTERIES (fig. 92). The pudic artery, with its inferior haemor- 

 rhoidal branch, and other small offsets of it, are now visible. 



The INTERNAL PUDIC ARTERY is derived from the internal iliac 

 in the pelvis, and in its course to the genital organs distributes 

 offsets to the perineum ; one portion will be laid bare in the 

 posterior, and the other in the anterior half of the perineum. 



As now seen, the vessel enters the hinder part of the ischio-rectal 

 fossa, and courses forwards along the outer wall at the depth of one 

 inch and a half at the back , but of only half an inch in front. It is 

 contained in an aponeurotic sheath formed by the obturator fascia. 

 The usual companion veins lie by its side ; and two nerves accom- 

 pany it, viz., the dorsal nerve of the penis, which is above it, and the 

 perineal branch of the pudic nerve which is nearer the surface. Its 

 offsets in this part of its course are the following : 



The inferior hcemorrhoidal branch arises as the artery enters the 

 ischio-rectal fossa, and is directed inwards across the space to the 

 anus, dividing into branches which supply the skin and fat, the 

 levator ani and sphincter muscles, and the lower end of the rectum. 

 On the gut it anastomoses with the other haemorrhoidal arteries. In 

 a well-injected body cutaneous branches may be seen to run forwards 

 to the anterior part of the perineum, and to communicate with the 

 superficial perineal artery. Other offsets turn upwards round the 

 edge of the gluteus maximus to the integument of the lower and 

 inner part of the buttock. 



Small muscular branches cross the front of the ischio-rectal fossa, 

 and supply the anterior part of the levator ani muscle. 



Veins accompany the arteries, and have a like course and ramifica- 

 tion : the pudic veins end in the internal iliac. 



NERVES (figs. 91 and 92). The nerves seen at this stage of the 

 dissection are the three divisions of the pudic trunk, a branch of the 

 fourth sacral nerve, and the perforating cutaneous offset of the sacral 

 plexus. 



The PUDIC NERVE is derived from the sacral plexus, and lies over 

 the small sacro-sciatic ligament with the artery in the buttock. 

 In the small sacro-sciatic foramen the nerve breaks up into the 

 three following branches, which enter the perineum : 



The inferior hcemorrhoidal branch crosses the ischio-rectal fossa, 

 and reaches the margin of the anus, where it terminates in offsets to 

 the integument and the sphincter muscle. Other cutaneous offsets 

 of the nerve run forwards over the fossa, and communicate with one 

 of the superficial perineal nerves, and with the inferior pudendal 

 (of the small sciatic) on the margin of the thigh. 



The perineal branch is the largest of the three divisions, and runs 



