MALE PERINEUM 355 



of the inferior ramus of the ischium close to the tuber- 

 osity. It passes medially and unites with the corresponding 

 muscle of the opposite side in the central point of the 

 perineum. 



The central point of the perineum is a tendinous septum, 

 situated in the middle line of the body, close to the posterior 

 end of the bulb and a short distance in front of the anus. 

 Towards this point a number of the perineal muscles converge 

 to obtain attachment. On each side, it gives attachment to 

 the superficial transverse perineal muscles ; posteriorly, to the 

 sphincter ani ; anteriorly, to the posterior fibres of the bulbo- 

 cavernosus ; whilst superiorly, the anterior fibres of the levator 

 ani descend to reach it. 



Musculus Bulbo-cavernosus (O.T. Hjaculator Urinse). This 

 muscle is spread over the bulb and posterior part of the corpus 

 cavernosum urethrae. It is composed of two symmetrical 

 halves, and its fibres take origin from the central point of 

 the perineum and from a fibrous median raphe which is 

 prolonged forwards between the two halves of the muscle. 

 The insertion differs according to the point at which the 

 muscle is examined. The posterior fibres are simply attached 

 to the superficial aspect of the inferior fascia of the urogenital 

 diaphragm ; the middle fibres, constituting the greater part of 

 the muscle, sweep around the corpus cavernosum urethrae, so 

 as to invest it completely, and are inserted into a common 

 aponeurosis upon the superior surface of this portion of the 

 penis ; lastly, the anterior fibres form two long narrow muscular 

 bands which diverge from each other like the limbs of the 

 letter V, and, passing forwards over the sides of the corpus 

 cavernosum penis, are inserted into an aponeurosis on the 

 dorsum of the penis. Thus the posterior fibres partially 

 embrace the bulb ; the middle fibres embrace the corpus 

 cavernosum urethrae ; whilst the anterior fibres embrace the 

 body of the penis. The bulbo-cavernosus supports the 

 urethra during micturition, and by its contraction it ejects 

 the last drops of urine or semen from the passage. 



Musculus Ischio-cavernosus (O.T. Erector Penis). The 

 ischio-cavernosus lies upon the crus penis. It arises by 

 fleshy fibres from the medial aspect of the tuber ischiadicum, 

 and is inserted by an aponeurotic expansion into the lower 

 and lateral surface of the anterior portion of the crus. 



Perineal Nerve. This is one of the two terminal branches 



