ABDOMINAL VISCERA IN MAN. 287 



The Descending Colon. — There is not much to be added to the 

 current descriptions of the descending colon. The upper portion 

 of the descending colon, together with the lowest part of the 

 splenic flexure, is, as a rule, the least distended part of the large 

 intestine, and presents many sacculations and is firmly fixed. 



The descending colon, passing downwards along the outer 

 border of the lower segment of the left kidney, presents in many 

 cases a well-marked bend inwards immediately below the lower 

 pole of the kidney. This bend is seen in varying degrees in 

 cases 7, 8, 26, 14, 6, 15, 16, 18, 19, 27, 33, and 34. The dis- 

 placement of the bend downwards in the case of a low position 

 of the left kidney is well shown in case 14. 



The descending colon in three cases (Nos. 9, 13, and 18) 

 passed downwards into a pocket beneath the outer border of the 

 psoas muscle, and was firmly fixed there by the peritoneum, and 

 required to take a sharp curve upwards and outwards around the 

 outer border of the muscle before passing downwards as the 

 sigmoid flexure. 



Surface Marking. — The descending colon commences, as a rule, 

 2-5 cm. below KF., with its outer border 10-6 cm. from the 

 middle hue. It continues downwards at this distance from the 

 middle line to about half-way between E.F. and CD. (to 6-2 cm. 

 below E.F.), where, opposite the lower pole of the left kidney, it 

 presents the bend inwards of nearly 2 cm., and the inner border 

 of the bowel almost reaches the lateral line. At the level of the 

 iliac crest it again bends outwards until its outer border in the 

 plane of CD. is 9*5 cm. from the middle line, and at I'l cm. 

 below CD. it begins to be attached over the psoas muscle and 

 passes into the sigmoid flexure. 



Sigmoid Flexure. — The sigmoid flexure usually continues down- 

 wards more or less firmly bound to the psoas, in a curve with its 

 convexity outwards, passing about 3 cm. interval to the anterior 

 superior iliac spine, until it reaches the brim of the pelvis about 

 the level of the anterior superior iliac spine, where it becomes 

 possessed of a well-marked mesentery of variable length, and 

 acquires a considerable degree of mobility. The lower border 

 of the sigmoid flexure as it passes over the pelvic brim is situ- 

 ated in the average 2"4 cm. below the anterior superior iliac 

 spine 5-6 cm. from the middle line ; but for practical purposes a 



