566 



ABDOMEN 



Dissection. The dissector must carefully define the anterior borders of 

 the levatores ani muscles, and then he must cut boldly through the centre 

 of the perineum between the bulb and the anal orifice until he reaches the 

 fascial interval between the posterior surface of the prostate and the front 

 of the lower, part of the rectum. When the interval is reached the knife 

 may be discarded and the forefinger introduced into the space and carried 

 from side to side. In this way it will be possible to demonstrate that the 

 visceral layer of the pelvic fascia, as it descends on the levator ani, divides 

 into a lower layer which passes behind the rectum, and a layer which 

 passes between the rectum and the prostate. (Fig. 220, p. 567.) 



The right levator must now be divided, from before backwards, about 

 midway between its origin from the parietal fascia and its insertion into 

 the wall of the anal passage, care being taken to avoid injury to the fascia 

 on its upper surface. The lower part of the muscle should be followed to 



Anal canal 



Obturator interims. 



Levator ani clothed on 



medial side by rectal 



fascia and on outer side 



by lower fascia of pelvic 



diaphragm 



Alcock's canal, con- ---' 

 taining pudendal 

 vessels and nerve 



FIG. 219. Diagram of the Endo-pelvic Fascia. The pelvis is divided in a 

 coronal plane and the pelvic fascia is represented in red. 



its insertion into the wall of the anal canal, and the mode of insertion 

 between the internal and the external sphincters noted. The upper part 

 should be turned laterally and the fingers of the left hand passed along 

 its upper surface till its origin from the fascia is reached. When this has 

 been done the dissector will find that the only structure which separates 

 his fingers from the cavity of the pelvis is the upper layer of the fascia of 

 the pelvic diaphragm (visceral layer of the pelvic fascia), which extends from 

 the parietal fascia, at the level of the origin of the levator ani, and passes 

 medially to the walls of the viscera, which it ensheathes. If the dissector 

 will now place the fingers of one hand on the upper surface of the visceral 

 fascia and those of the other hand on the lower surface, and then carry 

 both hands medially, he will find that the one hand passes on to the 

 upper surface of the bladder and the other behind the rectum. He will 

 thus demonstrate that as the visceral fascia crosses the pelvis from side 

 to side it separates into an upper or vesical layer and a lower or rectal 

 layer. The third or recto-vesical layer, which covers the posterior surface 

 of the prostate, and separates the gland from the rectum, has already 



