. MALE PERINEUM 151 



through the skin quite easily, as far back as the central point 

 of the perineum, but no further. Now pass a finger' through 

 the anus into the anal canal and note that the staff, as it 

 lies in the membranous part of the urethra, is again quite 

 easily felt ; but, at a higher level, as it passes through the 

 prostatic part of the urethra, it is less distinctly felt because 

 it is covered by the posterior part of the prostate. 



After the staff has been successfully passed and its 

 surroundings have been investigated with the finger, stitch the 

 most dependent part of the scrotum to the prepuce of the 

 penis, then drag both penis and scrotum forwards on the staff 

 and tie them in position. Next tie the handle of the staff to 

 the cord which passes between the flexed knee-joints of the 

 subject. Lastly introduce a little tow, steeped in preservative 

 fluid, into the anal canal and stitch up the orifice of the anus. 



Dissection. Reflection of Skin. Two incisions are required 

 (Fig. 75) : (i) a transverse incision along the line which 

 separates the anal from the urogenital triangle i.e. in front 

 of the ischial tuberosities ; (2) an incision at right angles to the 

 first, in the line of the median raphe. The second incision should 

 begin well forwards on the scrotum and be continued back a 

 little beyond the point of the coccyx. The knife should be carried 

 round the anus so as to encircle it. 



The four triangular flaps which are marked out should now 

 be reflected. Commence the reflection of each flap at its apex. 

 Some difficulty will be experienced in raising the posterior flaps. 

 It is due to the presence of a number of fasciculi of involuntary 

 muscle which radiate outwards from the anus. They form 

 collectively the corrugator cutis ani. When the skin has been 

 reflected the superficial fascia and the external sphincter muscle 

 will be exposed. 



Panniculus Adiposus (Superficial Fascia). The dissectors 

 must examine the superficial fascia carefully. It shows great 

 differences in character and texture in different parts of the 

 perineal area. At the sides of the anal canal in the ischio- 

 rectal fossae, which lie between the anal canal and the 

 tuberosities of the ischia, it is remarkable for the large 

 quantity of fat it holds in its meshes. That fat is soft 

 and lobulated, and passes upwards upon each side of the 

 anal canal in the form of a pliable and elastic pad. Over 

 the ischial tuberosities the superficial fascia under- 

 goes a striking alteration. In those situations it becomes 

 tough and stringy; dense fibrous septa separate the. lobules 

 of fat from one another and connect the skin with the 

 subjacent bone, and it acts as cushions upon which the 

 nlO c 



