OF THE FERINE I'M. 



461 



Transversus perinaei ; so that by the contraction of these muscles, which extend in 

 opposite directions, it serves as a fixed point of support. 



The Transversus perinaei is a narrow muscular slip, which passes more or less 

 transversely across the back part of the perineal space. It arises by a small tendon 

 from the inner and fore part of the tuberosity of the ischium. and, passing inward, 

 is inserted into the central tendinous point of the perinaeum, joining in this situation 



FIG. 297. The perinaeum. The integument and superficial layer of superficial fascia reflected. 



with the muscle of the opposite side, the External sphincter ani behind, and the 

 Accelerator urinae in front. 



Nerve-supply. The perineal branch of the internal pudic. 



Actions. By their contraction they serve to fix the central tendinous point of 

 the perinaeum. 



The Accelerator urinae (Ejaculator seminis, or Bulbo-cavernosus) is placed in 

 the middle line of the perinaeum. immediately in front of the anus. It consists of 

 two symmetrical halves, united along the median line by a tendinous raphe. It 

 arises from the central tendon of the perinaeum. and from the median raphe in 

 front. From this point its fibres diverge like the plumes of a pen ; the most 

 posterior form a thin layer, which are lost on the anterior surface of the triangular 

 ligament ; the middle fibres encircle the bulb and adjacent parts of the corpus 

 spongiosum. and join with the fibres of the opposite side, on the upper part of the 

 corpus spongiosum. in a strong aponeurosis : the anterior fibres, the longest and 

 most distinct, spread out over the sides of the corpus cavernosum, to be inserted 

 partly into that body, anterior to the Erector penis, occasionally extending to the 

 os pubis ; partly terminating in a tendinous expansion, which covers the dorsal 

 vessels of the penis. The latter fibres are best seen by dividing the muscle 

 longitudinally, and dissecting it outward from the surface of the urethra. 



Action. This muscle serves to empty the canal of the urethra, after the 

 bladder has expelled its contents ; during the greater part of the act of micturition 

 its fibres are relaxed, and it only comes into action at the end of the process. The 

 middle fibres are supposed, by Krause. to assist in the erection of the corpus 



