PLATE LVIII. 



THE ISCHIO-RECTAL FOSSA, AND SUPERFICIAL VIEW 

 OF THE PERINEUM. 



In this dissection the skin and superficial fascia have been removed, and the fossa 

 ni))iied of its fat. On the right side, the fasciie bounding it deeply have been left 

 inuict ; while on the left side the anal fascia has been removed to expose the levator ani, 

 and the obturator fascia cut into to show Alcock's canal, which contains the internal 

 pudic vessels and nerve. 



The deep layer of the superficial perineal fascia (Colles's fascia) has been left to 

 show how it covers the superficial perineal muscles, turning round the trans- 

 versus porinoi to form the anterior boundary of the ischio-rectal fossa, and to join the 

 anterior layer of the triangular ligament. Late- 

 rally it is attached to the lower border of the pubic 

 and ischial rami as far as the tuber, and in front 

 passes into the dartoid tissue of the scrotum, 



niiig continuous with the fascia of Scarpa. 

 In the middle line a vertical septum descends to the 

 'null), completely dividing the space into two be- 

 hind, but incomplete in front : hence in rupture 

 of the urethra the urine must pass forwards 

 upwards the scrotum in order to gain the opposite 

 .side ; it cannot pass back into the ischio-rectal 

 fossa because the fascia of Colles joins the an- 

 terior layer of the triangular ligament. If the 

 internal surface of the rami of the ischium and 

 pubes be examined, it will be seen that the inner 

 of their lower border turns somewhat in- 

 wurd, forming the inner margin of the tuber 

 ischii ; this is joined by another faint line whicli 

 runs along the inner surface of the bone from the 

 bottom of the symphysis pubis. The fascia of 

 Colles (E) is attached to the former, while the 

 latter receives the attachment of the anterior 

 layer of the triangular ligament (F), the space 

 between giving attachment to the crus (A), erector 

 penis (B), and transversus perinei (c). 



The ischio-rectal fossa is bounded : 



In front. By Colles's fascia turning over the transversus perinei to join tho anterior 

 layer of the triangular ligament. 



Behind. By the tip of the coccyx. 



Externally. By the tuber ischii and obturator fascia covering the obturator 

 internus, edge of gluteus maximus, and great sacro-sciatic ligament. 



Internally. By the anal fascia covering the levator ani, and the external sphincter. 



Contents. Inferior hiemorrhoidal vessels and nerve which cross the space, super- 

 ficial perineal vessels and nerve, the perineal branch of the fourth sacral, and the 

 padding of fat. 



The internal pudic vessels and nerve can be felt in the outer wall of the fossa 

 running in tbe obturator fascia. 



IXNEB VIEW OP PcnEs AND ISCHFCM. 



A, Crus penis ; B, Erector penis ; c, Trans- 

 vcrsus perinei; i>, Compressor uretlini'; 

 E, Fascia of Colles ; F, Anterior layer of 

 triangular ligament. Tbe dotted line 

 shows about the position of the posterior 

 layer of the triangular ligament. 



