COLON. 



1221 



The phrenico-colic ligament is formed in the fcetus from the left margin of the greater 

 lentum (Jonnesco). 

 The peritoneal covering o.f the left colic flexure is similar to that of the descending colon. 



Colon Descendens. The descending colon is much narrower and less obtrusive 

 than the ascending colon : indeed in a large number of cases it is found firmly 

 contracted. It begins in the left hypochondrium at the left flexure, passes down 

 on the left side of the abdomen, and ends in the lumbar region, opposite the crest 

 of the ilium, by passing into the iliac colon. Its course is not quite straight, for it 

 first curves downwards and medially along the lateral border of the left kidney, 

 and then descends almost vertically to the iliac crest (Fig. 957). 



Its length is usually from 4 to 6 inches (10 to 15 cm.), and its width, which is 

 less than that of the ascending colon, about 1J inches (37 mm.). 



6th costal cartilas 



7th costal cartilage 

 Lig. teres 



8th costal cartilage 



Gall-bladder 



9th costal cartilage 



Liver 



10th costal cartilage 



Duodenum 

 light flexure of colon 

 Kidney 



Caecum 

 Ileum* 



Vermiform process 



. 



Xiphoid process 

 th costal cartilage 



7th costal cartilage % 



Stomach 



8th costal cartilage 

 Transverse colon 

 9th costal cartilage 



10th costal cartilage 



Duodeno-jejunal 



flexure 



~ Kidney 



Descending colon 

 Mesentery, cut 



Bifurcation of abdominal 

 aorta 



...- Iliac colon 

 .- Pelvic colon 



- Urinary bladder 



. 957. THE ABDOMINAL VISCERA AFTER THE REMOVAL OF THE JEJUNUM AND ILEUM (from a photograph 

 of the same body as depicted in Fig. 942). The transverse colon is much more regular than usual. - 



Relations. The descending colon first lies in contact with the lateral border of 

 the left kidney; below that it is placed, like the colon of the opposite side, in the angle 

 between the psoas and quadratus lumborum muscles. Posteriorly, it rests upon the 

 lower part of the diaphragm above, and on the quadratus lumborum below. 

 Anteriorly (and somewhat laterally also, except when the bowel is distended) 

 are placed numerous coils of small intestine, which hide the colon completely from 

 view, and compress it against the posterior abdominal wall. To its medial side lies 

 the inferior part of the kidney above, the psoas major below. 



In the great majority of bodies only the front and sides of the descending 

 colon are covered with peritoneum (Fig. 968) ; the posterior surface, being destitute 

 of a serous coat, is connected to the posterior wall of the abdomen by areolar 

 tissue. In a small proportion of cases, on the other hand, the serous coat is com- 

 plete, and the colon is furnished with a short mesentery. 



Up to the fourth or fifth month of foetal life the descending colon has a complete investment 

 of peritoneum and a long mesentery. After the fifth month the mesentery adheres to, and soon 



78 I 



