Physiologically, bile duct is any tube-like structure that carries bile. However, in anatomic descriptions, the term bile duct actually refers to the “Common Bile Duct”.
Origin of common bile duct:
Common bile duct is about 3 inches long and is formed by the union of cystic duct and common hepatic duct.
Course of common bile duct:
In the first part of its course, it lies in the right free margin of the lesser omentum in front of the epiploic foramen. At this location, it lies in front of the portal vein and to the right of the hepatic artery.
In the second part of its course, it is situated behind the first part of duodenum, to the right of gastroduodenal artery.
In the third part of its course, it lies in a groove on the posterior surface of the head of pancreas. This is the location where the common bile duct joins the main pancreatic duct.
Termination of common bile duct:
The bile duct ends by entering the wall of second part of the duodenum. Usually, it is joined by the main pancreatic duct and together they open into a small ampulla in the wall of duodenum. This ampulla is commonly known as hepatopancreatic ampulla (ampulla of Vater). It opens into the lumen of the duodenum through a small papilla, known as the major duodenal papilla.
The terminal part of both the common hepatic and the main pancreatic ducts as well as the ampulla are surrounded by circular muscle known as the sphincter of the hepatopancreatic ampulla (sphincter of Oddi).
In contrast to the most common arrangement described above, occasionally, the bile and pancreatic ducts open separately into the duodenum.