COLON. 1219 



bounded in front by a small peritoneal process, the ileo-colic fold (Fig. 956, A), containing 

 the anterior csecal artery. 



The recessus ileocsecalis superior lies at the upper margin of the opening of the 

 ileum into the colon, and is bounded behind by the ileum, to the right by the 

 Ccecum. 



(d) Recessus Retrocaecalis. This is an occasional recess which passes upwards between 

 the ascending colon and the posterior abdominal wall. Its orifice looks downwards or to 

 the left, and lies in the fossa ctecalis behind the caecum. 



COLON. 



Colon Ascendens. The ascending colon begins about the level of the inter- 

 tubercular plane, opposite the ileo-caecal orifice, where it is continuous with the 

 caecum. From there it runs upwards and somewhat posteriorly, with a slight con- 

 cavity to the left, until it reaches the inferior surface of the liver, where it bends 

 forwards and to the left, and passes into the right flexure of the colon (Fig. 957). 

 In its course it lies in the angle between the quadratus lumborum, and the more 

 prominent psoas major medially (Fig. 957). 



It is situated chiefly in the right lumbar region, but it extends slightly into 

 the hypochondrium above ; and, although ifr usually begins about the level of the 

 intertubercular plane, still with a low position of the caecum it will extend further 

 down, and may occupy a considerable part of the iliac region. 



Its length is extremely variable, depending upon the extent to which the caecum 

 has descended from the position it occupied during development, viz., in contact 

 with the under surface of the liver. 



It is from 5 to 8 inches long, and it is wider and more prominent than the 

 descending colon. It generally presents several minor curves or flexures, and 

 it often has the appearance of being pushed into a space which is too short to 

 accommodate it. 



Relations. Anteriorly, it is usually in contact with the abdominal wall, but the 

 small intestine frequently intervenes, particularly above (Fig. 957). To its medial 

 side lie the coils of the small bowel and the psoas major ; to the lateral side is the 

 side wall of the abdomen. Its posterior surface, which is free from peritoneum 

 as a rule (Fig. 968), is connected by areolar tissue to the iliacus muscle as far up as 

 the crest of the ilium, to the quadratus lumborum above that, and finally to the 

 inferior part of the right kidney. 



In the great majority of cases only the two sides and the anterior surface are 

 covered with peritoneum, the posterior surface being destitute of a serous coat (Fig. 

 968). In a small proportion of bodies, however, the ascending colon is provided 

 with a complete peritoneal coat and a mesentery, but this latter is so short that it 

 admits of but a slight amount of movement in the gut. 



On the lateral aspect of the caecum and colon there are occasionally found 

 small peritoneal pockets termed recessus paracolici. 



Like the csecum, the ascending colon is frequently found distended with gas or faeces after 

 death, hence in part its large size and prominence as compared with the descending colon, which 

 is generally empty. 



Flexura Coli Dextra. The right (O.T. hepatic) flexure of the colon is the 



bent piece of the large intestine between the end of the ascending colon and the 

 beginning of the transverse colon (Figs. 947 and 957). 



When the ascending colon reaches the inferior surface of the liver, it bends 

 usually acutely, sometimes obtusely forwards and to the left on the anterior surface 

 of the right kidney, and on reaching the front of the descending portion of the 

 duodenum, passes into the transverse colon. 



The flexure is placed between the descending duodenum medially and the 

 anterior thin margin of the liver, or the side wall of the abdomen, laterally ; above, 

 it corresponds to the colic impression on the liver, and posteriorly it rests on the 

 kidney. Its peritoneal relations are similar to those of the ascending colon. 



Colon Transversum. This is the long and looped portion of the large intestine 



78 a 



