62 THE PERINEUM OF THE MALE. 



THE PERINEUM OF THE MALE. 



The perineum is the region which is included within the outlet of the pelvis, and 

 which is traversed by the lower end of the rectum and by the urethra. It extends, 

 therefore, from the apex of the subpubic arch in front to the tip of the coccyx 

 behind, and from the ischial tuberosity of one side to that of the other. It is 

 bounded on each side, at the fore part, by the conjoined rami of the pubis 

 and ischium, and at the back part by the great sacro-sciatic ligament, together 

 with a portion of the lower border of the gluteus maximus muscle. Its form is 

 rather heart-shaped in consequence of the projection of the coccyx posteriorly ; it 

 measures about three and a half inches (9 cm.) from side to side, and about four 

 inches (10 cm.) over the curved surface (three and a quarter inches in a straight 

 line) from before back in the middle line. The perineal space is separated from 

 the pelvic cavity above by the recto-vesical fascia and the levatores ani muscles ; 

 its depth is considerable (from two to three inches) at the posterior and outer 

 part, much less (not exceeding an inch) at the fore part. 



The perineal space is conveniently divided into two parts by a line drawn across 

 from one ischial tuberosity to the other, and passing immediately in front of 

 the anus. The anterior division is termed the urethral part, and is often referred 

 to as the true perineum ; the posterior division is called the anal part, or the false 

 perineum. 



The several muscles and fasciae, vessels and nerves, which enter into the 

 formation of the perineum have been fully described in the second and third volumes 

 of this work, and it now only remains to give a short sketch of its superficial 

 and topographical anatomy, with which may be included also the relations of 

 the adjoining parts of the pelvic viscera. 



Superficial anatomy. The osseous portions of the boundaries of the 

 perineum can be felt more or less distinctly through the skin, but the anterior 

 portion of the subpubic arch is obscured by the presence of the penis, and the ischial 

 tuberosities are at some distance from the surface, being covered by a thick layer of 

 fat and, in the erect position, also by the great gluteal muscles. The sacro-sciatic 

 ligament is scarcely to be distinguished beneath the gluteus maximus, except in 

 very thin subjects. The lower part of the coccyx is very plainly felt. The anus is 

 placed directly between the ischial tuberosities, its centre being about one inch and 

 a half from the extremity of the coccyx. 



The skin of the perineum is thin and provided with more or less abundant 

 hairs ; it is gathered into puckered folds round the anus, to which a farther 

 irregularity is often given by swollen haemorrhoidal veins. In front of the anus is a 

 median ridge, the raphe, which runs forwards and is continued on to the scrotum 

 and penis. Beneath this, the bulb of the urethra forms a slight median elevation, 

 more perceptible in emaciated subjects. In such subjects, again, the fat in the 

 ischio-rectal fossa does not reach the level of the ischial tuberosities so as to form a 

 rounded surface sinking in towards the anus, as is the case in those who are well 

 nourished. A fine white line round the anus indicates the point of junction of the 

 skin and mucous membrane, and corresponds precisely to the division between the 

 external and internal sphincters (Hilton). 



One inch (2'5 cm.) in front of the anus is situated the central point of the 

 perineum, which corresponds to the centre of the free border of the triangular 

 ligament. Immediately in front of this, the bulb of the urethra commences, but 

 the membranous part perforates the triangular ligament about half an inch farther 

 forwards, and therefore one inch and a half (4 cm.) in front of the anus. 



Topographical anatomy. The superficial fascia of the perineum consists of 



