|Latin m. sphincter ampullae|
The sphincter of Oddi (also hepatopancreatic sphincter or Glisson's sphincter), abbreviated as SO, is a muscular valve that controls the flow of digestive juices (bile and pancreatic juice) through the ampulla of Vater into the second part of the duodenum. It is named after Ruggero Oddi. The sphincter of Oddi is relaxed by the hormone cholecystokinin via vasoactive intestinal peptide.
Opiates can cause spasms of the sphincter of Oddi, leading to increased serum amylase levels.
In many mammals (including mice, guinea pigs, dogs and opossums), the smooth muscle around the ampulla of Vater does not form a sphincter.
The sphincter was described for the first time by Ruggero Oddi when he was a young student in 1887. This followed extensive research on the physiology of dogs and had made detailed histological examinations of humans, and many other species.