440 



TJie Perineum 



dangerous. Sometimes the swelling is about the size of a filbert, and 

 it may feel almost as hard as one. The surgeon waits neither for 

 fluctuation nor redness, but deeply incises the perineum along the 

 middle line. A perineal fistula results, but this gets well as the stric- 

 ture, which was the original cause of the abscess, is dilated. 



Right superficial, left 



deep dissection : 

 a, anus. 

 6, bulb. 



c, coccyx. 



d, ischium. 



<*, superficial fascia. 

 ./, fat in ischio-rectal 



fossa. 

 g, glutens maximus. 



1, transverse muscle. 



2, erector penis. 



3, trans, artery. 



4, int. pudic artery, 

 and 5, its haemor- 

 rhoidal branches. 



6, first layer of triang. 

 ligament removed to 

 show artery of bulb 

 and Cowper's gland. 



Beneath the deep layer of the superficial fascia, on either side, is a 

 muscular triangle, the base of which is formed by the tritiisvcrsi/s 

 pcrinci, which runs from the ischial tuberosity to the central tendon ; 

 at the outer side is the erector penis, which passes from the tuberosity 

 to the side of the corpus cavernosum, whilst in the middle line is the 

 accelerator urincc, surrounding the bulb, and sending its most posterior 

 fibres into the triangular ligament ; its most anterior fibres encircle the 

 corpus cavernosum, to blend with those of the opposite side over the 



