The Pelvis. 283 



on the upper part of its anterior surface only, and from 

 this surface it is reflected on to the bladder in the male, 

 and to the vagina in the female. 



Relations. Behind, this portion of the rectum is in re- 

 lation with the sacrum and coccyx, being separated from 

 them by connective tissue, chiefly, while, in front, it is in 

 relation with, in the male, the triangular surface of the 

 bladder, bounded by the vesiculae seminales laterally, 

 and by the prostate gland in front. In the female, the 

 anterior surface is in relation with the vagina and with 

 the cervix uteri. This portion of the rectum follows the 

 curve of the sacrum, and is, therefore, directed down- 

 wards and forwards ; whereas, the second portion, which 

 extends from the tip of the coccyx to the anus, is about one 

 and a half inches in length and is directed downwards 

 and backwards. The second portion is surrounded by 

 the internal sphincter muscle and has the levator ani mus- 

 cle attached to it on either side. At its termination in the 

 anus the external sphincter encircles it. Bloodvessels. 

 The rectum is supplied by the superior hemorrhoidal from 

 the inferior mesenteric, by the middle hemorrhoidal from 

 the internal iliac, and by the inferior hemorrhoidal from 

 the internal pudic. The superior hemorrhoidal descends 

 in the sigmoid meso-colon and bifurcates, giving a branch 

 to either side of the bowel. These break up, about five 

 inches from the anus, into three or four branches, which 

 anastomose with branches of the middle hemorrhoidal, 

 and then send smaller vessels, which pierce the muscular 

 coat of the bowel, about two inches lower down, and run 

 downwards towards the anus, between that coat and the 

 mucous membrane, lying parallel to one another. The 

 veins pursue a course somewhat similar to the artery ; 

 some, especially those corresponding to the middle and 

 inferior hemorrhoidal arteries, going to the internal 



