MALE PERINEUM 163 



cavernosus muscles, to the scrotum, to the dartos muscle 

 and integument of which it is distributed in the form of 

 numerous long, slender branches, called the posterior scrotal 

 arteries. Before it reaches the scrotum, it supplies twigs to 

 the superficial perineal muscles. It is accompanied by the 

 posterior scrotal branches of the perineal nerve. 



The transverse perineal artery is a small vessel which usually 

 springs from the preceding. It pierces the base of the fascia 

 of Colles, and, gaining the surface of the superficial trans- 

 verse perineal muscle, proceeds medially to the interval 

 between the rectum and the bulb of. the urethra, where it 

 ends by supplying the parts in that locality, and by ana- 

 stomosing with the corresponding vessel of the opposite side. 



The posterior scrotal nerves are branches of the perineal 

 division of the pudendal nerve. They appear in the anterior 

 part of the ischio-rectal fossa after piercing the obturator 

 fascia. Then they pierce the base of the fascia of Colles 

 and pass forwards in the superficial pouch to the scrotum. 



The long perineal branch of the posterior cutaneous nerve of 

 the thigh (O.T. long pudendal nerve) pierces the deep fascia of 

 the thigh a short distance in Iront of the ischial tuberosity, 

 and about an inch and a half to the lateral side of the 

 margin of the pubic arch. As it proceeds forwards it inclines 

 medially, and, piercing the attachment of Colles' fascia to 

 the margin of the pubic arch, it accompanies the other 

 vessels and nerves to the scrotum, the lateral and anterior 

 part of which it supplies. 



After the superficial vessels and nerves, which lie in the 

 perineal pouch on each side, have been examined, the dis- 

 sector must proceed to display the other contents of the 

 superficial pouch, viz. the three parts of the root of the penis; 

 they are the bulb of the urethra, which lies in the median 

 plane, and the right and left crura of the penis, which are 

 attached to the corresponding borders of the pubic arch ; the 

 bulbo-cavernosus muscle which covers the bulb of the urethra, 

 the ischio-cavernosus muscles which cover the crura of the 

 penis, and the superficial transverse muscles of the perineum 

 which lie parallel with the base of the superficial pouch. 

 When those structures have been studied he must seek, on 

 each side, the dorsal nerve of the penis, the terminations of 

 the deep branch of the perineal nerve, and three branches 

 of the internal pudendal artery, viz., the artery of the bulb, 

 ii 11 a 



