Organ
Sphincter of Oddi
A muscular valve system at the duct outlets
High-yield
This is a complex with biliary, pancreatic and ampullary components, rather than one uniform circular band.
Overview
At the duodenal entry of the biliary and pancreatic ducts, specialized smooth muscle controls resistance to secretion outflow. Components surround the terminal ducts and, when present, their common ampulla. The arrangement varies with the way the ducts join.
Reference facts
- Location
- Within the medial wall of the descending duodenum, surrounding terminal biliary and pancreatic passages.
- Parts
- Traditionally described as choledochal, pancreatic and ampullary muscle components; ductal and muscular configurations vary.
- Blood supply
- Small branches of the pancreaticoduodenal arterial network.
- Innervation
- Enteric and autonomic pathways regulate muscle activity. Meal-related signals, including the hormone cholecystokinin, coordinate reduced outlet resistance with gallbladder emptying.
- Relations
- Deep to the mucosa near the major duodenal papilla and continuous with the terminal duct region.
- Function
- Regulates secretion entry, limits duodenal reflux and contributes to diversion of bile toward the gallbladder between meals.
Clinical correlation
Endoscopic sphincterotomy alters this outlet during selected biliary interventions. Pain after gallbladder removal does not by itself establish a sphincter disorder: the EPISOD trial found no benefit from sphincterotomy for otherwise unexplained postcholecystectomy pain without significant obstructive findings.
Frequently asked questions
Where is the sphincter of Oddi located?
Within the medial wall of the descending duodenum, surrounding terminal biliary and pancreatic passages.
What does the sphincter of Oddi do?
Regulates secretion entry, limits duodenal reflux and contributes to diversion of bile toward the gallbladder between meals.
What are the parts of the sphincter of Oddi?
Traditionally described as choledochal, pancreatic and ampullary muscle components; ductal and muscular configurations vary.
What is the blood supply of the sphincter of Oddi?
The sphincter of Oddi is supplied by the small branches of the pancreaticoduodenal arterial network.