The ampulla of Vater is surrounded by which structure?

The ampulla of Vater, also known as the hepatopancreatic ampulla, is a critical anatomical structure where the bile duct and the main pancreatic duct converge and empty their contents into the duodenum. Surrounding the ampulla of Vater is the Sphincter of Oddi, which is a smooth muscle valve regulating the flow of bile and pancreatic juice into the small intestine.

The Sphincter of Oddi plays a vital role in digestion; when it is contracted, it prevents bile and pancreatic juice from entering the intestine, allowing for the storage of these fluids within the gallbladder and pancreas. When the sphincter relaxes, it facilitates the release of these digestive juices into the duodenum to aid in the digestion of fats and other nutrients.

The other mentioned structures, while related to different parts of the digestive system, do not surround the ampulla of Vater. The pyloric sphincter controls the passage of food from the stomach to the duodenum, the cardiac sphincter (also called the lower esophageal sphincter) regulates the entry of food into the stomach from the esophagus, and the lower esophageal sphincter prevents the backflow of stomach contents into the esophagus.