384 HUMAN ANATOMY. 



The iscliio-rectal region contains the external and internal 

 sphincters, the corrugator cutis ani and the ischiorectal fossa. 

 The latter is a pyramidal cavity, its apex reaching to the junction 

 of the obturator and anal fascia, and its base formed by the 

 skin. It is bounded 



Behind, by the edge of the great sacro-sciatic ligament and 

 gluteus maximus and coccygeus muscles ; internally, by the leva- 

 tor ani, covered by the anal fascia, sphincter ani, and coccygeus 

 muscle ; externally, by the tuber ischii and obturator fascia. 



/Interior lay tr f 

 Ditf PtT * 



FIG. 169. 

 Male perineum, superficial dissection. (Lydston.) 



It contains: 



The internal pudic artery, nerve, and veins; 

 The inferior haemorrhoidal vessels and nerves; 

 The perineal and fourth sacral nerves; and 

 A mass of areolar tissue. 



PERINEUM. 



The perineum is the triangular space between the anus and 

 scrotum in the male, and between the anus and vulva in the 

 female. The skin is dark, thin, and supplied with sebaceous and 

 sudoriparous glands, and is marked by middle line or raphe. 



