The pancreatic duct begins in the tail of the pancreas (Fig. 4.109). It passes to the right through the body of the pancreas and, after entering the head of the pancreas, turns inferiorly. In the lower part of the head of the pancreas, the pancreatic duct joins the bile duct. The joining of these two structures forms the hepatopancreatic ampulla (ampulla of Vater), which enters the descending (second) part of the duodenum at the major duodenal papilla. Surrounding the ampulla is the sphincter of ampulla (sphincter of Oddi), which is a collection of smooth muscles.