Papilla of Vater

The main papilla of Vater (named after an Italian) is a small nipple-like structure on the wall of the duodenum, in its "second part." The duodenum is the upper part of the small intestine, into which food flows from the stomach. The papilla forms the main exit hole for the bile and pancreatic juices which flow down the bile duct and pancreatic duct. Rarely there are two separate holes close together within the same papillary nipple. The papilla remains closed at rest, because of the activity of a muscular valve (sphincter) The sphincter (of Oddi, another Italian) surrounds the exit of the bile duct and pancreatic duct. It opens by reflex action when foods enter the stomach, so that juices can be released to help in their digestion. In most people there is a second smaller (minor, or accessory) papilla, situated about 2 cm (3/4 inch) above the main papilla, and slightly to its right. This is the exit hole for Santorini's duct. The minor papilla acts as a useful safety valve when the main papilla is not able to function correctly, but becomes the main site of drainage for pancreatic juices in the rare congential disease of pancreas divisum.