386 



DISSECTION OF THE PELVIS. 



Rectum ; 

 extent and 

 length ; 



course and 

 supports ; 



Covered by 

 peritoneum ; 



with care the remains of the sheath of the vesicula seminalis, 

 defining at the same time the vas deferens internal to the latter. 



The RECTUM, or last part of the great intestine (h'gs. 144 and 

 145, &), extends from the third piece of the sacrum at the termina- 

 tion of the pelvic colon to a little more than an inch in front of 

 the tip of the coccyx where it bends downwards and backwards as 

 the anal canal. It is about five inches in length. The bowel 

 follows the curve of the sacrum and the coccyx, and is supported 

 mainly by the peritoneum, the recto-vesical fascia, and the perineal 

 muscles. 



It lies behind the bladder, and is covered by peritoneum in front 



FIG. 145. SIDE VIEW OF THE DISSECTED MALE PELVIS. 



a. Urinary bladder partly filled. 



b. Prostate. 



c. Membranous part of the urethra. 



d. Spongy part of the urethra. 



e. Crus penis, divided. 

 /. Vas deferens. 



g. Vesicula semiualis. 



h. Ureter. 



'. Recto-vesical fascia. 



k. Rectum. 



I. Levator ani, cut. 



for about the upper two-thirds of its extent, and on the sides for 

 its upper third only (p. 376). Immediately below this it pierces 

 the recto-vesical fascia, and receives its sheath from that membrane, 

 relations.- Resting on it is the triangular base of the bladder, with the vesiculae 

 seminales and vasa deferentia ; and beneath it are the sacrum and 

 coccyx. On each side is the coccygeus muscle. 



Part not After the peritoneum leaves it, the rectum is directed down- 



perftoifeum ; wards and forwards from the end of the coccyx, through the hinder 



part of the perineum, for a distance of about one inch and a half, 



