386 DISSECTION OF THE PERINEUM. 



CHAPTER VII. 



DISSECTION OF THE PERINEUM. 



SECTION I. 



PERINEUM OF THE MALE. 



DIRECTIONS. The perinaeum may be allotted with greatest advantage 

 to the dissector of the abdomen ; and its examination should be made first, 

 as the distinctness of many of the parts is destroyed soon after death. 

 Before the body is placed in the position suited for the dissection, the 

 stud&pt may practise passing the catheter along the urethra. 



Position of the body. Whilst the body lies on the Back it is to be 

 drawn to\he end of the dissecting table, till the buttocks project slightly 

 over the edge ; and a moderately-sized block is to be placed beneath the 

 pelvis, to raise the perinaeum to a convenient height. The legs are to be 

 raised and kept out of the way by the following means : After the knees 

 have been bent, and the thighs bent upon the trunk, the limbs are to be 

 fastened with atord in their raised position. For this purpose make one 

 or two turns of the cord around one bent knee (say the right) ; carry the 

 cord beneath the table, and, encircling the opposite limb in the same man- 

 " ner, /fasten it finally round the right knee. When the position has been 

 arranged, let the student raise the scrotum, and place a small piece of 

 ^ cotton wool or tow within the anus, but let him avoid distending the 

 rectum. 



Superficial limits and marking. The perinatal space in the male is 

 limited, on the surface of the body, by the scrotum in front-, and by the 

 thighs and buttocks on the sides and behind. 



This region is of a dark color, and is covered with hairs. In the middle 

 line is the aperture of the anus, which is posterior to a line extended from 

 .the anterior part of the one ischial tuberosity to the other. In front of 

 the anus the surface is slightly convex over the urethra, and presents a 

 . longitudinal prominent line or raphe, which divides this part of the space 

 into two halves. Between the anus and the tuberosity of the hip bone the 

 surface is somewhat depressed over the hollow of the subjacent ischio-rectul 

 fossa, especially in emaciated bodies. 



The margin of the anal aperture possesses numerous converging folds, 

 but these are more or less obliterated by the position of the body and the 

 distension of the rectum ; and projecting oftentimes through and around 

 the opening are some dilated veins (haemorrhoids). 



Deep boundaries. The deep boundaries of the perinaeal space will be 

 ascertained, in the progress of the dissection, to correspond with the infe- 

 rior aperture or the outlet of the pelvis. The limits may be seen on a dry 



