UPDATED: The [common bile duct] also known as the [ductus choledocus]. is part of the hepatobiliary tree, taking bile from the gallbladder and liver to the  second portion of the duodenum. The common bile duct begins at the junction of the common hepatic duct with the cystic duct, it continues inferiorly, usually to the right of the proper hepatic artery and anterior to the portal vein. It then  passes posterior to the first portion of the duodenum, is surrounded by pancreatic tissue and ends at the hepatopancreatic ampulla of (Vater).

The junction of the common bile duct with the hepatopancreatic ampulla of (Vater) is the narrowest portion of the hepatobiliary tree, The lodging of a gallstone at this junction can be the cause for choledocholitiasis and jaundice.