MALE PERINEUM 155 



nozzle of the bellows, or injection pipe, through the incision and 

 compress the margins of the opening round it, then force air into 

 the pouch. The air which is introduced first will fill one side of 

 the pouch, then it will pass forwards to the scrotum, where the 

 septum is incomplete, and will force its way across the median 

 plane to the opposite side. Afterwards, as more air is forced in, 

 it will pass forwards to the abdomen. The pouch is thus rendered 

 prominent and the attachments of the fascia of Colles become 

 evident. The air cannot pass into the anal triangle owing to the 

 union of the fascia of Colles with the base of the fascia of the 

 urogenital diaphragm ; it cannot pass down the medial aspect of 

 the thighs, on account of the attachment of the fasciae to the sides 

 of the pubic arch ; it can only force its way forwards under the 

 superficial fascia and dartos muscle of the scrotum, and thence 

 on to the penis and the anterior aspect of the abdomen. By the 

 means suggested the dissector will obtain a very striking view 

 of the course which would be taken by urine escaping from a 

 rupture in the urethra below the urogenital diaphragm. 



The attachments of the fascia of Colles are so important that 

 the student should test them by dissection also. To do that it 

 is necessary to make two incisions through the superficial fascia. 

 Enter the knife in the middle line at the root of the scrotum, and 

 carry it backwards and laterally to the tuber ischii on each side 

 of the body. A central A. -shaped flap and two collateral flaps 

 of fascia are thus marked out. When the central portion is 

 raised and turned backwards, the septum of the pouch is brought 

 into view, and the attachment of the fascia to the base of the 

 urogenital diaphragm is demonstrated. When the collateral 

 flaps are turned aside each will be seen to be firmly fixed to the 

 border of the pubic arch. As this dissection is made the utmost 

 care is demanded on the part of the dissector. In the areolar 

 tissue immediately subjacent to the superficial fascia are the 

 superficial perimal vessels and scrotal nerves, which are certain 

 to be injured, or perhaps even reflected with the fascia, unless 

 the greatest caution is exercised. 



ANAL TRIANGLE. 



The dissection of the anal portion of the perineal space 

 will disclose the following parts : 



1. The external sphincter ani muscle. 



2. The anal canal, covered by the levator ani muscle and the inferior 



fascia of the pelvic diaphragm. 



3. The obturator fascia. 



4. The lower border of the glutaeus maximus muscle and the ligamentum 



sacro-tuberosum (O.T. great sacro- sciatic). 



5. The ano-coccygeal body. 



6. The inferior hgemorrhoidal vessels and nerve. 



7. The perineal artery. 



8. The perineal branch of the fourth sacral nerve. 



9. The perineal nerve and its branches. 



10. The perforating cutaneous branch of the second and third sacral nerves. 



