262 



MUSCLES OF THE PERIX^EUM. 



The superficial or external sphincter is a thin lay'er of fibres placed 

 Immediately beneath the skin surrounding the margin of the anus. It 

 is elliptical in form, about half an inch in breadth on each side of the 

 anus, and is attached posteriorly by slight tendon to the tip and back of 

 the coccyx ; passing forwards on each side of the anus, it becomes blended 

 anteriorly with the transverse and the bulbo-cavernosus muscles at the 

 central point of the perinceum, a name given to the depressed spot situated 

 in the male between the anus and the bulb of the urethra, and in the female 

 between the anus and vulva. 



Fig. 202. SUPERFICIAL VIEW OP 

 THE MUSCLES OF THE PERINEUM 

 IN THE MALE (modified from 

 Bourgery). \ 



a, crest of the pxabis ; the penis 

 cut short at this place ; &, coccyx ; 

 c, placed on the tuberosity of the 

 ischium, points by the line to the 

 greater sacro-sciatic ligament ; x , 

 placed within the anus ; 1, placed 

 on the spongy body of the urethra, 

 in front of the bulbo-cavernosus 

 muscles ; 2, placed on the central 

 point or tendon of the perinseum, 

 marks the posterior extremity of the 

 same muscles ; 3, ischio-cavernosus ; 

 4, transversus perinaei ; 5, levator 

 ani ; from 2 to 6, elliptical sphincter 

 of the anus ; surrounding x , the 

 circular sphincter is indicated ; 6, 

 coccygeus muscle ; 7, adductor lon- 

 gus ; 8, gracilis ; 9, adductor mag- 

 nus ; 10, semitendinosus and biceps ; 

 11, on the left side, the gluteus raaxi- 

 mus entire ; 11', the same cut on the 

 right side, so as to expose a part of the coccygeus muscle. 



The levatores ani and coccygei are two expanded muscles continuous one 

 with the other, which together form a floor of support for the pelvic viscera, 

 and close in a great measure the lower orifice of the pelvis. 



The levator ani arises in front from the posterior surface of the pubes, 

 near the symphysis and midway between its upper and lower borders ; 

 behind from the spine of the ischium, and between those points from the 

 pelvic fascia along the line of attachment of the obturator fascia. Some of 

 its fibres are also traceable upwards in the substance of the pelvic fascia 

 above the level of the obturator. 



From this extensive origin the fibres of the levator proceed downwards 

 and inwards towards the middle line of the floor of the pelvis. Its posterior 

 fasciculi are inserted upon the side of the lower end of the coccyx ; the 

 bundles immediately in front of the coccyx unite in a median raphe with 

 those of the opposite sides as far forward as the margin of the anus ; the 

 middle and larger portion of the muscle is prolonged upon the lower part of 

 the rectum, where it is connected with the fibres of the external sphincter, 

 and slightly with those of the internal ; and lastly, the anterior muscular 

 bundles pass between the rectum and the genito-urinary passages, and, 

 descending upon the side of the prostate, unite beneath the neck of the 



