350 ABDOMEN 



border. At the upper and lower ends of the vertical incision 

 make short transverse incisions, and turn aside the flaps, so 

 formed. Clean the interior of the duodenum with a sponge, 

 and then examine the mucous membrane. Note that the mucous 

 membrane of the descending part is thrown into numerous and 

 large plicae circulares, and that, as a rule, it is deeply stained by bile. 

 Look for a longitudinal fold of the mucous membrane, the plica 

 longitudinalis, which lies at the junction of the medial and 

 posterior walls, nearer the lower than the upper end. It serves 

 as a guide to the duodenal papilla, which frequently lies at its 

 upper extremity, usually concealed by one of the largest of the 

 plicae circulares (Fig. 159). Pass a small probe through the 



FIG. 161. Pars Descendens of the Duodenum, opened from the right side. 

 Showing the aperture for the passage of the bile and pancreatic juice 

 on the upper part of the posterior face of the plica longitudinalis. 

 There was no duodenal papilla. 



opening on the apex of the papilla into the ampulla. Make an 

 opening in the lower part of the bile-duct, and pass a small 

 probe along the duct into the ampulla ; perform the same opera- 

 tion on the main pancreatic duct ; then cut down through the 

 medial wall of the gut and open up the lumina of the ducts, the 

 cavity of the ampulla of Vater, and its orifice of communi- 

 cation with the interior of the duodenum. 



The dissector should note that whilst the duodenal papilla 

 usually lies at the upper end of the plica longitudinalis (Figs. 

 158, 159) it may be situated on the middle of the plica (Fig. 160), 

 and it may be absent. In the latter case the aperture through 

 which the bile and the pancreatic juice enter the duodenum lies 

 in a recess, at the side of the upper part of the plica longitudinalis 

 (Fig. 161). 



Vena Portse (Portal Vein). Blood is carried to the liver 

 both by the hepatic artery and by the portal vein. The 



