Major duodenal papilla

The major duodenal papilla is a small conical mucosal elevation or mucosal crater located on the posteromedial wall of the second (descending) part of the duodenum, approximately 8-10 cm distal to the pylorus. It is situated at the inferior end of the longitudinal fold of the duodenum and marks the site where the hepatopancreatic ampulla (ampulla of Vater) opens into the duodenal lumen.

The hepatopancreatic ampulla is usually formed by the union of the common bile duct and the main pancreatic duct (duct of Wirsung) before they pierce the wall of the duodenum. Through the major duodenal papilla, bile and pancreatic secretions are delivered into the duodenum to aid digestion. The flow of these secretions is regulated by the sphincter of Oddi, a smooth muscle sphincter surrounding the terminal parts of the ducts and the ampulla.

Blood supply, lymphatics, and innervation

The blood supply of the region is derived from the superior and inferior pancreaticoduodenal arteries, while venous drainage follows corresponding veins into the portal venous system. Lymphatic drainage is to the pancreaticoduodenal and superior mesenteric lymph nodes. Innervation is provided by autonomic fibres from the coeliac and superior mesenteric plexuses.

Clinical correlates

The major duodenal papilla is an important landmark during endoscopic retrograde cholangiopancreatography (ERCP), where it is cannulated to access the biliary and pancreatic duct systems. Obstruction of the papilla by gallstones, inflammation, scarring, or periampullary tumours can impede the drainage of bile and pancreatic secretions, leading to obstructive jaundice, ascending cholangitis, or acute pancreatitis.