THE ABDOMINAL CAVITY 317 



can be obtained by bringing out a tube in the right loin through 

 the lumbar triangle (of Petit), lateral to the right kidney, and the 

 displaced viscera may then be returned to thejr original positions. 



When a stone is impacted in the ampulla of Vater, a more 

 direct approach is obtained by the trans-duodenal route. A 

 vertical incision is made in the supra-colic portion of the second 

 part of the duodenum, and the stone can then be felt under the 

 mucous coat of the postero-medial wall. The orifice of the 

 duodenal papilla lies under cover of one of the plicae circulares 

 (valvulse conniventes), and may sometimes be located by 

 expressing some bile from it. 



The exit from the ampulla of Vater is then enlarged by 

 slitting it in an upward direction until it permits of the extraction 

 of the stone. 



The bile-duct may be exposed to considerable pressure from 

 the head of the pancreas in malignant disease or in chronic 

 pancreatitis, on account of the intimate relation of the two 

 structures. In the former, the steadily increasing obstruction 

 is accompanied by the gradual onset of jaundice, which slowly 

 but surely increases in intensity ; in chronic pancreatitis the 

 colour changes are more irregular. It sometimes happens that 

 a calculus ulcerates from the duct into the gland and constitutes 

 a foreign body in the head of the pancreas, which can only be 

 removed by incising the gland. 



The Pancreas is an elongated gland, which crosses the 

 posterior abdominal wall from right to left with an upward 

 inclination. It consists of a head, a neck, a body and a tail, 

 and, with the exception of the tail, which usually lies between 

 the two layers of the lieno-renal ligament, it is entirely retro- 

 peritoneal. 



The head lies in the concavity of the duodenum and is 

 covered anteriorly by the pylorus, above, and the transverse 

 colon, below. Posteriorly, it rests upon the inferior vena cava and 

 the right renal vessels, and is grooved by the bile-duct (p. 315). 



The neck passes upwards and to the left to become continuous 

 with the body. It is covered anteriorly by the peritoneum on 

 the posterior wall of the omental bursa and supports the pyloric 

 end of the stomach. Behind it the superior mesenteric and 

 splenic veins unite to form the portal vein. 



The body of the pancreas crosses the middle line at or a 

 little below the transpyloric plane. It is somewhat triangular 

 on section and consequently possesses three surfaces. The 



