Surgical Anatomy of the Perineum and 

 Ischio-Rectal Region. 



Dissection, The student should select a well-developed muscular subject, free from fat ; and 

 the dissection should be commenced early, in order that the parts may be examined in as 

 recent a state as possible. A staff having been introduced into the bladder, and the subject 

 placed in the position shown in fig. 389, the scrotum should be raised upwards, and retained in 

 that position, and the rectum moderately distended with tow. 



The space which is now exposed, corresponds to the inferior aperture or outlet 

 of the pelvis. Its deep boundaries are, in front, the pubic arch and sub-pubic 

 ligament ; behind, the tip of the coccyx ; and on each side, the ramus of the pubes 

 and ischium, the tuberosity of the ischium, and great sacro-sciatic ligament. The 

 space included by these boundaries is somewhat lozenge-shaped, and is limited on 

 the surface of the body by the scrotum in front, by the buttocks behind, and on 

 each side by the inner side of the thighs. It measures, from before backwards, 

 about four inches, and about three in the broadest part of its transverse diameter, 

 between the ischial tuberosities. A line drawn transversely between the anterior 

 part of the tuberosity of the ischium, on either side, in front of the anus, sub- 

 divides this space into two portions. The anterior portion contains the penis and 

 urethra, and is called the perineum. The posterior portion contains the termina- 

 tion of the rectum, and is called the ischio-rectal region. 



ISCHIO-EECTAL KEGIOJST. 



The Ischio-rectal region corresponds to the portion of the outlet of the pelvis 

 situated immediately behind the perineum : it contains the termination of the 

 rectum. A deep fossa, filled with fat, is seen on either side of the intestine, 

 between it and the tuberosity of the ischium: this is called the ischiol-rectal 

 fossa. 



The ischio-rectal region presents, in the middle line, the aperture of the anus : 

 around this orifice the integument is thrown into numerous folds, which are 

 obliterated on distension of the intestine. The integument is of a dark color, 

 continuous with the mucous membrane of the rectum, and provided with numerous 

 follicles, which occasionally inflame and suppurate, and may be mistaken for 

 fistulas. The veins around the margin of the anus are occasionally much dilated, 

 forming a number of hard, pendent masses, of a dark bluish color, covered partly 

 by mucous membrane, and partly by the integument. These tumors constitute 

 the disease called external piles. 



Dissection. Make an incision through the integument, along the median line, from the base 

 of the scrotum to the anterior extremity of the anus ; carry it round the margins of this aperture 

 to its posterior extremity, and continue it backwards about an inch behind the tip of the coccyx. 

 A transverse incision should now be carried across the base of the scrotum, joining the anterior 

 extremity of the preceding ; a second, carried in the same direction, should be made in front of 

 the anus ; and a third, at the posterior extremity of the gut. These incisions should be sufficiently 

 extensive to enable the dissector to raise the integument from the inner side of the thighs. The 

 flaps of skin corresponding to the ischio-rectal region (figs. 389 392) should now be removed. In 

 dissecting the integument from this region, great care is required, otherwise the External sphincter 

 will be removed, as it is intimately adherent to the skin. 



The superficial fascia is exposed on the removal of the skin ; it is very thick, 

 areolar in texture, and contains much fat in its meshes. In it are found ramifying 



