MALE PERINEUM 345 



How to verify these facts. The student can verify these facts in two 

 ways, viz. (i) by inflating the pouch with air, and (2) by dissection. 

 Make a longitudinal incision, large enough to admit the nozzle of the 

 bellows (or better still an injection pipe fitted to a bicycle- pump), into the 

 superficial fascia towards the back part of the pouch and a little to one side 

 of the middle line. This cut must be carried through the fascia until the 

 fibres of the superficial perineal muscles are exposed. In using the pump 

 the margins of the opening into the pouch must be held tightly around the 

 nozzle of the pipe. The air which is introduced passes forwards, and is 

 first confined to one side of the pouch. Reaching the scrotum, however, 

 where the septum is incomplete, it forces its way across the middle line, 

 and inflates the opposite side of the pouch. The pouch is now rendered 

 prominent, and the attachments of the fascia become very evident. The 

 air cannot pass into the rectal 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 fascia 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 from this 

 on to the penis and along the spermatic cords to the anterior aspect of the 

 abdomen. By this means the dissector obtains 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 also test them by dissection. To do this 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 posteriorly and laterally to the 

 tuber ischii on each side of the body. A central /^-shaped flap and two 

 lateral flaps of fascia are thus marked out. By raising and turning back- 

 wards the central portion, 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 lateral flaps are turned aside each will be seen to 

 be firmly fixed to the border of the pubic arch. In effecting this dissection 

 the utmost care is demanded on the part of the student. In the areolar 

 tissue immediately subjacent to the superficial fascia are the superficial 

 perineal vessels and scrotal nerves, which are certain to be injured, or perhaps 

 even reflected with the fascia, unless the greatest caution be exercised. 



ANAL TRIANGLE. 



The dissection of this 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 anal fascia. 



3. The parietal or obturator layer of pelvic fascia. 



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



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



5. The coccygeus muscle. 



6. The inferior hsemorrhoidal 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, 



