508 



COLON RECTUM. 



Fig. 222.* appendix varies in length from one to five or six 



inches ; it is about equal in diameter to a goose- 

 quill, and is connected with the posterior and 

 left aspect of the caecum near 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 in- 

 complete valve. Occasionally the peritoneum in- 

 vests the caecum so completely as to constitute a 

 meso-caecum, which permits of an unusual degree 

 of movement in this portion of the intestine, and 

 serves to explain the occurrence of hernia of the 

 caecum upon the right side. The caecum is the 

 most dilated portion of the large intestine. 



The Colon is divided into ascending, trans- 

 verse, 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, descends (descending colon) through the left lumbar 

 region to the left iliac fossa, where it makes a remarkable curve upon 

 itself, which is called the sigmoid flexure. 



The ascending colon, the most dilated portion of the large intestine, 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 abdominal parietes ; behind 

 with the quadratus lumborum muscle and right kidney ; internally with the 

 small intestine and the perpendicular portion of the duodenum ; and by its 

 upper extremity with the under surface of the liver and gall-bladder. The 

 transverse colon, the longest portion of the large intestine, forms a curve 

 across the cavity of the abdomen, the convexity of which looks forwards 

 and sometimes downwards. It is in relation, by its upper surface, with the 

 liver, gall-bladder, stomach, and 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 the abdominal parietes ; 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 abdominal parietes ; 

 behind, with the iliac fossa, and, on either side, with the small intestine. 



The Rectum is the termination of the large intestine. It has received 

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

 ness of its form in comparison with the colon. It descends, from opposite 



* The caecum, showing its appendix, the entrance of the ileum, and the ileo-capcal 

 valve, t. The caecum. 2. The commencement of the colon. 3. The ileum. 4. The 

 aperture of entrance of the ileum into the csecum. 5. 5. The ileo-caecal valve. 6. The 

 aperture of the appendix vermiformis cseci. 7. The appendix vermiformis. 8,8. Sac- 

 culx of the colon, separated, by valvular septa. 9. The falciform frsenum of the appendix 

 Yeriniformis. 



