34o ABDOMEN 



ABDOMEN. 



WHEN the body is brought into the dissecting-room, it is first 

 placed in the lithotomy position (Fig. 127), and is retained 

 in that posture for three days, during which time the dis- 

 sector of the abdomen is expected to dissect the perineum. 



MALE PERINEUM. 



Boundaries of the Perineum. The perineum may be 

 said to correspond to the inferior aperture or outlet of the 

 pelvis. It is necessary, then, that the student should renew 

 his acquaintance with this part of the skeleton before he 

 begins the dissection. Let him obtain a pelvis with the liga- 

 ments in situ. He will observe that he has to deal with a 

 diamond-shaped space, and that it has the following bound- 

 aries : anteriorly^ the symphysis pubis and the arcuate pubic 

 ligament (O.T. sub-pubic) ; posteriorly ', the coccyx ; and on each 

 side from before backwards, the rami of the pubis and ischium, 

 the tuberosity of the ischium, and the ligamentum sacro-tuber- 

 osum (O.T. great sciatic). If he now turn his attention to 

 the subject before him he can readily identify these limits. 

 The ligamentum sacro-tuberosum, however, is somewhat 

 obscured, from its being covered by the glutseus maximus 

 muscle, but it can be felt by pressing deeply in a line between 

 the ischial tuberosity and the coccyx (Figs. 127 and 128). 



In the undissected body the superficial area of the perineum 

 is very limited; indeed, when the limbs are extended and 

 approximated (as is the case when one stands erect), it merely 

 consists of a narrow groove running forwards between the 

 thighs from the coccyx towards the pubis. In this groove 

 are placed the anus or orifice of the anal canal and the roots 

 of the scrotum and penis, whilst in the middle line a cutaneous 

 ridge the median raphe may be seen. This raphe can 

 be traced from the anus forwards over the scrotum and along 

 the under surface of the penis. 



Subdivision of the Space. The perineal space has, there- 

 fore, a diamond-shaped form, and it is customary to subdivide 



