262 THE DIGESTIVE SYSTEM 



medial to the tip of the ninth costal cartilage of the right side. 

 The fundus can be mapped out on the surface in the angle 

 between the right costal margin and the linea semilunaris, which 

 corresponds to the lateral border of the rectus abdominis muscle. 



Inferiorly, the gall-bladder is in contact with the duodenum 

 and the commencement of the transverse colon, and it may 

 become adherent to the latter after attacks of cholecystitis. 

 Under these circumstances, gall-stones may rupture into the 

 colon and be discharged by the bowel (PI. II.). 



The neck of the gall-bladder narrows to form the cystic 

 duct, which enters the porta hepatis and unites with the 

 hepatic duct to form the bile duct. The mucous membrane 

 which lines the cystic duct is redundant and projects into the 

 lumen in the form of oblique folds. These folds may help to 

 prevent the passage of gall-stones from the gall-bladder into 

 the bile duct. 



The Bile Duct is formed by the union of the cystic with 

 the common hepatic duct at the porta hepatis. It descends 

 from the liver in the right free margin of the lesser omentum, 

 where it lies in front of the portal vein (Fig. 90). It then 

 passes behind the first part of the duodenum and, at the 

 upper border of the head of the pancreas, it diverges from the 

 portal vein, running downwards and laterally behind the 

 head of the pancreas to terminate in the second part of the 

 duodenum (Fig. 97). 



In the first, or supra-duodenal, part of its course the bile duct 

 may be compressed by tumours of the liver or by enlarged 

 lymph glands in the porta hepatis. As the duct is closely 

 related to the portal vein in this situation, pressure which 

 affects the duct is almost certain to affect the vein as well. 



In the retro-duodenal part of its course, the duct may be 

 obstructed by tumours of the pylorus, which also affect the 

 portal vein. In the terminal part of its course, the duct is not 

 so closely related to the vein, and tumours of the head of the 

 pancreas or chronic pancreatitis are less likely to exert pres- 

 sure on the vein. They commonly compress the duct 



