DISSECTION OF THE PERINEUM IN THE MALE. 27'i 



and it passes transversely inwards to terminate on the middle line ovei 

 the urethra, being confounded with its fellow of the opposite side, anc 

 with the first fibres of the accelerator urinse. 



Action. — To dilate the bulbous part of the urethra. 



The Accelerator Uein^. These muscles (right and left) cover th( 

 sides and lower face of the urethra from the ischial arch to the free 

 extremity of the penis. Along the inferior median line of that tube th( 

 right and left muscles are joined by an intermediate fibrous raphe 

 From this raphe the fibres pass round the urethra on each side, with i 

 slightly forward inclination, and are lost on the upper aspect o: 

 the tube, but without reaching the middle line. Beneath the anus th( 

 first fibres of the muscle seem to arise from the retractor penis muscle 

 but elsewhere the retractor is superficial to the intermediate raphe o: 

 the right and left muscles. 



Action. — The muscles of opposite sides always act together ; and wher 

 they do so, they diminish the calibre of the urethra and expel its con 

 tents. In this way they are instrumental in the ejaculation of semen 

 In micturition the muscles ordinarily do not come into play until th< 

 close of the act, when they empty the urethra from behind to before 

 The necessity for this action exists because the expelling power of th( 

 bladder is lost as soon as its own cavity is emptied. 



The Erector Penis. This is a thick, dark-red muscle covering th( 

 crus penis. Its fibres arise from the inferior ischiatic spine (of th( 

 tuber), and they terminate on the crus. 



Action. — To aid in erecting the penis by compressing the crus anc 

 thus retarding the return of blood from the cavernous body of th< 

 penis. 



THE scrotum (plate 37). 



Position. — Let the subject remain in the dorsal position, but unfastei 

 the rope from one of the hind limbs, and allow the trunk to incline t( 

 the same side. The loose limb should be fastened backwards out of th< 

 way. 



Directions. — Grasp the neck of the scrotum close to the wall of thi 

 abdomen, so as to tighten the skin over the testicle, and then tie a piece 

 of soft cord round the constricted neck of the scrotum. This will facili 

 tate the dissection of the different layers of the pouch. 



The scrotum is the bag, or pouch, in which the testicles are sus 

 pended. It is laminated, arid comprises the following layers : — 



1. The Scrotal Integument. This is continuous with the surround 

 ing skin, of which it is a modified portion. It is thin, with short fint 

 hairs, and numerous sebaceous glands, whose secretion renders it moist 

 It is traversed mesially by a raphe, continuous posteriorly with th< 

 median raphe of the perinteum. The scrotal integutoent forms a singl* 

 bag for the two testicles. \j 



