842 



SURGICAL ANATOMY OF THE PERINEUM. 



areolar tissue of the scrotum, penis, and anterior and lateral portions of the 

 abdomen; it rarely extends into the areolar tissue on the inner side of the 

 thighs, or backwards around the anus. This limitation of the extravasated 

 fluid to the parts above named is easy of explanation, when the attachments 



Fig. 456. The Perineum. The Integument and Superficial Layer of Superficial Fascia reflected. 



of the deep layer of the superficial fascia are considered. When this fascia is 

 removed, the muscles connected with the penis and urethra will be exposed; 

 these are, in the middle line, the Accelerator Urinae; on each side, the Erector 

 Penis, and behind, the Transversus Perinsei. 



The Accelerator Urinse is placed in the middle line of the perineum, immedi- 

 ately 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 

 perineum, 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 part 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; partly terminating in a tendinous expan- 

 sion, which covers the dorsal vessels of the penis. The latter fibres are best 

 seen by dividing the muscle longitudinally, and dissecting it outwards from the 

 surface of the urethra. 



Action. This muscle may serve to accelerate the flow of the urine or semen 

 along the canal of the urethra. The middle fibres are supposed, by Krause, to 

 assist in the erection of the corpus spongiosum, by compressing the erectile 

 tissue of the bulb. The anterior fibres, according to Tyrrel, also contribute to 

 the erection of the penis, as they are inserted into, and continuous with, the 

 fascia of the penis, compressing the dorsal vein during the contraction of the 

 muscle. 



