Bile duct

Recommended video: Liver in situ [18:21]

Liver in situ seen from an anterior view of the abdomen with the liver retracted.

The bile duct is a small channel (tube) through which bile from the liver is delivered into the duodenum.

Bile is a digestive product made by the liver. It acts to emulsify fats, breaking large fat globules into smaller ones. Bile leaves the liver via biliary ducts continuously and is stored in the gall bladder until needed. The biliary ducts combine to form the left and right hepatic ducts, which in turn combine to form the common hepatic duct. During digestion, bile is released by the gallbladder into the cystic duct. The cystic duct joins with the common hepatic duct to form the bile duct. Bile then travels through the bile duct towards the duodenum of the small intestine.

The bile duct joins the pancreatic duct at the hepatopancreatic ampulla, these two ducts then empty their products (bile and pancreatic juice, respectively) together into the duodenum via the major duodenal papilla. Both the bile duct and the pancreatic duct have sphincters which control the emptying of these liquids into the dilated hepatopancreatic ampulla. These sphincters are named the sphincter of bile duct and sphincter of pancreatic duct. As it descends, the bile duct passes posterior to the duodenum then posterior to the head of the pancreas, lying in a fissure (groove) in the pancreatic head.

The portal triad is the name given to three vessels that travel together within the hepatoduodenal ligament of the liver. The three vessels are the hepatic artery, hepatic portal vein and bile duct. The bile duct receives blood supply from four different arteries. The cystic artery supplies the proximal part, the right hepatic artery supplies the middle part, and the posterior superior pancreaticoduodenal artery and gastroduodenal artery supplies the distal part.