373 THE LAEGE INTESTINE. 



the other at the lower end of the bowel, forming a shorter turn in the 

 opposite direction. 



Unlike the rest of the large intestine, the rectum is not sacculated, 

 but is smooth and cylindrical ; and it has no separate longitudinal 

 bands upon it. It is about eight inches in length, and at its 

 upper end is rather narrower than the sigmoid flexure, but becomes 

 dih^ted into a large ampulla or reservoir immediately above the 

 anus. 



The upper part of the rectum, covered by peritoneum, is in contact 

 in front with the bade of the bladder (or uterus in the female), unless 

 some convolutions of the small intestine hoppen to descend between 

 them. The ureter and branches of the internal iliac artery are in 

 contact with it on the left side. It is attached behind to the sacrum 

 by a duplicature of peritoneum named the mcso-redum. Lower down 

 the peritoneum covers the intestine in front and at the sides, and at last 

 in front only ; still lower, it quits the intestine altogether, and is re- 

 flected forwards to ascend in the male upon the back of the bladder, in 

 the female on the back of the upper part of the vagina and the uterus. 

 In passing from the rectum to the bladder, the peritoneum forms a cul- 

 de-sac, the recto-vesical pouch, which extends downwards between the 

 intestine and the bladder to within an inch or more from the base of 

 the prostate, and is bounded above at each side by a lunated fold of the 

 serous membrane, of which the left is almost always the larger (pos- 

 terior ligaments of the bladder). 



Below the }}oint where the peritoneum ceases to cover it, the rectum 

 is connected to surrounding parts by areolar tissue, which is mostly 

 loaded with fat. In this way it is attached behind to the front of the 

 sacrum and the coccyx, and at the sides to the coccygei and levatores 

 ani muscles. In front, it is in immediate connection with a trian- 

 gular portion of the base of the bladder (fig. 272, v'); on each side of 

 this, with the vesiculas seminales ; and farther forwards, with the under 

 surface of the prostate (^j). Below the prostate, where the rectum turns 

 downwards to reach the anus, it becomes invested by the fibres of 

 the internal sphincter, and embraced by the levatores ani muscles, by 

 which, as well as by the triangular ligament of the urethra, it is sup- 

 ported. Lastly, at its termination it is surrounded by the external 

 sphincter ani muscle. 



In the lemale, the lower portion of the rectum is firmly connected 

 with the back of the vagina. 



For convenience of description the rectum is sometimes divided ar]:)itrarily into 

 three parts ; the first or uppennost, about o^ inches long, extending- to the centre 

 of the 3rd sacral vertebra : the middle part (o inches) from this point to the tip 

 of the coccyx ; whilst the lowennost, about an inch and a half long, ciu'ves baclc 

 to the anus. 



Structure of the rectum. — The rectum differs in some respects 

 from the rest of the large intestine, in the structure of both its muscular 

 and its mucous coats. 



The mi/scular coat is very thick : the external or longitudinal fibres 

 form a uniform layer around it, and cease near the lower end of the 

 intestine; the internal or circular fibres, on the contrary, become more 

 numerous in that situation, where they form what is named the internal 

 sphincter muscle. The longitudinal fibres are paler than the circular 



