COLON RECTUM. 503 



length, from one to five or six inches ; it is about equal in diameter 

 tff a goose-quill, and is connected with the posterior and left aspect 

 of the caecum near to the extremity of the ileum. It is usually more 

 or less coiled upon itself, and retained in that coil by a falciform 

 duplicature of peritoneum. Its canal is extremely small, and the 

 orifice by which it opens into the caecum not unfrequently provided 

 with an incomplete valve. Occasionally the peritoneum invests the 

 caecum .so completely as to constitute a meso-caecum, which per- 

 mits of an unusual degree of movement in this portion of the intes- 

 tine, and serves to explain the occurrence of hernia .of the caecum 

 upon the left side. The caecum is the most dilated portion of the 

 large intestine. 



The Colon is divided into ascending, transverse, and descending. 

 The ascending colon passes upwards from the right iliac fossa, 

 through the right lumbar region, to the under surface of the liver. 

 It then bends inwards, and crosses the upper part of the umbilical 

 region under the name of transverse colon, and on the left side de- 

 scends (descending colon) through the left lumbar region to the left 

 iliac fossa, where it makes a remarkable curve upon itself, which is 

 called the sigrnoid flexure. 



The ascending colon, the most dilated portion of the large intes- 

 tine, next to the caecum, is retained in its position in the abdomen 

 either by the peritoneum passing simply in front of it or by a narrow 

 meso-colon. It is in relation in front with the small intestine and 

 with the abdominal parietes ; behind with the quadratus lumborum 

 muscle and with the right kidney ; internally with the small intestine 

 and with the perpendicular portion of the duodenum ; and by its 

 upper extremity with the under surface of the liver and with the 

 gall-bladder. The transverse colon, the longest portion of the large 

 intestine, forms a curve across the cavity of the abdomen, the con- 

 vexity of which looks forwards and sometimes downwards. It is 

 in relation by its upper surface with the liver, the gall-bladder, the 

 stomach, and with the lower extremity of the spleen ; by its lower 

 surface with the small intestine ; by its anterior surface with the 

 anterior layers of the great omentum and with the abdominal pari- 

 etes ; and by its posterior surface with the transverse meso-colon. 

 The descending colon is smaller in calibre, and is situated more 

 deeply than the ascending colon. Its relations are precisely similar. 

 The sigmoid flexure is the narrowest part of the colon ; it curves in 

 the first place upwards and then downwards, and to one or the other 

 side, and is retained in its place by a meso-colon. It is in relation 

 in front with the small intestine and with the abdominal parietes ; 

 behind with the iliac fossa ; and on either side with the small intes- 

 tine. 



The Rectum is the termination of the large intestine. It has re- 

 ceived its name, not so much from the direction of its course, as 

 from the straightness of its form in comparison with the colon. It 

 descends from opposite the left sacro-iliac symphysis, in front of 

 the sacrum, forming a gentle curve to the right side, and then re- 



