THE ABDOMEN 



MALE PERINEUM. 



Landmarks. — The tuber ischii can be felt on either side, as well as 

 the ischio-pubic ramus ; but the great sacro-sciatic ligament cannot 

 be felt, on account of the thickness of the lower border of the gluteus 

 maximus. The tip of the coccyx is very accessible to the finger. 



The perineum practically corresponds with the outlet of the pelvis, 

 and is somewhat lozenge-shaped, having the subpubic angle in 

 front, the tip of the coccyx behind, and the tuber ischii on either 

 side. It is conveniently divided into two parts by a line con- 

 necting the ischial tuberosities, each division being triangular. 

 The anterior represents the uro-genital or urethral division, this 

 being the perineum proper, and the posterior the ischio-recteil or 

 anal division. The skin of the mo-genital division presents an 

 antero-posterior median elevation, called the perineal raphe, which 

 extends over the posterior and anterior surfaces of the scrotum, and 

 along the under surface of the penis. The position of the deeply- 

 placed central tendinous point of the perineum is indicated by 

 taking a point in this raphe very nearly i inch in front of the anus. 



The anus is the external opening of the anal canal. It is situated 

 posterior to a line connecting the front parts of the ischial tuber- 

 osities, and about li inches from the tip of the coccj^. A delicate 

 white line surrounds the anus where the skin cind mucous mem- 

 brane meet, which indicates the separation between the external 

 and internal sphincter muscles (Hilton). The position of each 

 ischio-rectal fossa is indicated by a slight depression between the 

 anus and tuber ischii. 



Deep Boundaries of the Perineum — Anterior. — ^The subpubic 

 angle and subpubic ligament. Posterior. — ^The coccyx. Lateral. 

 — From behind forwards, the inferior border of the great sacro- 

 sciatic ligament, tuber ischii, and ischio-pubic ramus. 



Ischio-Rectal Division. 



Cutaneous Nerves. — These are (i) the hemorrhoidal or perineal 

 branch of the lower part of the anterior primary division of the 



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