204: SURGICAL ANATOMY OF 



portions of the crura. Lying somewhat obliquely to the 

 central tendon are' the transverse muscles of the perineum. 

 This central tendon is a white fibrous knot, and acts as 

 a point d'appui for the accelerators urinse and external 

 sphincter muscles ; it is situated in the median line be- 

 tween the urethra and the anus. Lying between and 

 upon the erectores penis and the acceleratores urinae, are 

 the trunks of the superficial perineal vessels and nerve, 

 and some inosculating branches of the inferior pudendal, 

 and on or below the posterior border of the transversus 

 perinei muscle lie the transverse perineal vessels and nerve. 

 The acceleratores urina? are separated from the deep 

 layer of superficial fascia by a thin aponeurotic layer. 

 This muscle, which compresses the bulb, and empties 

 the bulbous urethra, is generally described as consisting 

 of three portions, commencing from the median raphe, 

 an anterior, which passes round the penis to be inserted 

 on its upper aspect, sending an expansion which com- 

 presses the dorsal vein ; a middle, which incloses the in- 

 ferior portion of the urethra, and passes between it and 

 the body of the penis; and a posterior, which is attached 

 to the anterior surface of the triangular ligament. 



It will be observed that the perineal muscles of one 

 side form a triangular space, having the triangular liga- 

 ment as its floor, while from its outer angle emerge the 

 superficial perineal vessels, and the transverse perinei 

 vessels and nerves coming to the surface ; the relations 

 of the space are of importance, as in the lateral operation 

 of lithotomy the first incision traverses it. 



If the accelerator urinse muscle be now carefully de- 

 tached by making an incision along the raphe, the bulb 

 of the urethra is exposed, small in childhood, and large 



