MALE PERINEUM 167 



which arises from the medial aspect of the ramus of the 

 ischium close to the tuberosity. 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 it a number of the perineal muscles converge 

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

 a superficial transverse perineal muscle ; 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. 



M. Bulbo-cavernosus (O.T. Ejaculator Urinae). The bulbo- 

 cavernosus 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 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 an 

 aponeurosis upon the superior surface of that 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. They pass forwards, over the sides of the corpus 

 cavernosum penis, and 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. 



M. Ischio-cavernosus (O.T. Erector Penis). The ischio- 

 cavernosus lies upon the crus penisr^ It arises by fleshy 

 fibres from the medial aspect of the ramus of the ischium 

 close to the tuberosity, and is inserted, by an aponeurotic 

 expansion, into the lower and lateral surface of the anterior 

 portion of the crus. 

 ii lie 



