3 o6 THE ABDOMEN AND PELVIS 



duodenum is fixed in position. In retro-peritoneal exploration 

 of the lower end of the bile-duct (p. 316) it must be rendered 

 movable so that it can be turned downwards, forwards, and to 

 the left. This can be effected by incising the peritoneum over 

 the right kidney along the lateral border of the upper end of 

 the second part of the duodenum (Kocher). 



If necessary, this incision may be extended downwards 

 along the lateral margin of the right colic flexure and the 

 ascending colon. The duodenum and the ascending colon can 

 then be lifted off the right kidney and turned to the left (Fig. 

 96). In freeing the duodenum, the right renal vessels are 

 exposed as they lie in close relation to its posterior surface 

 (see also p. 316). 



The Horizontal or Third Part of the duodenum runs 

 transversely to the left in front of the ureter, the inferior vena 

 cava, and the aorta to end at the left side of the third lumbar 

 vertebra. It lies behind the peritoneum in the right infra-colic 

 compartment, but at its termination it is crossed by the root 

 of the mesentery. The superior mesenteric vessels and accom- 

 panying nerves run downwards over its anterior surface and 

 enter the root of the mesentery (Fig. 88). This relationship 

 is of great importance in the condition of enteroptosis. The 

 weight of the small intestine, hanging down into the pelvis, 

 stretches the superior mesenteric artery tightly across the third 

 part of the duodenum, producing obstruction which may lead 

 to acute dilatation of the stomach. 



The head of the pancreas lies in contact with the upper 

 border of this part of the duodenum ; in the groove between 

 these two structures the inferior pancreatico-duodenal artery 

 (p. 323) runs towards the right. 



The Ascending or Fourth Part of the duodenum runs 

 upwards, and slightly to the left, to the duodeno-jejunal flexure. 

 Its left side is covered by the peritoneum on the posterior wall 

 of the left infra-colic compartment, while its right side is in 

 contact with the pancreas and the aorta. 



At the left side of the second lumbar vertebra the fourth part 

 of the duodenum bends sharply forwards, downwards, and to 

 the left to form the Duodeno-Jejunal Flexure. This bend lies 

 in contact with the inferior surface of the pancreas immediately 

 below the root of the transverse meso-colon. It can be found 

 by passing the hand backwards behind the greater omentum to 

 the posterior abdominal wall, and then carrying it upwards along 



