What anatomical feature prevents bile reflux from the duodenum?

The sphincter of Oddi plays a crucial role in regulating the flow of bile and pancreatic juice into the duodenum and preventing bile reflux. This sphincter is located at the junction of the common bile duct and the duodenum, specifically at the ampulla of Vater. When functioning properly, it opens to allow bile to flow from the gallbladder through the common bile duct into the duodenum during digestion, particularly after the ingestion of fats.

When the digestive processes are not in play, the sphincter of Oddi remains closed, which prevents the backflow of bile from the duodenum into the biliary system. This regulation is essential for maintaining the proper digestive environment and preventing complications, such as bile reflux, which could lead to duodenitis or other gastrointestinal issues.

The other anatomical features mentioned do not serve this specific function. The pyloric sphincter controls the passage of food from the stomach to the duodenum but is not responsible for regulating bile flow. The cardiac sphincter is located at the esophagus and prevents gastroesophageal reflux, while the internal anal sphincter is involved in the control of bowel movements. Each of these sphincters has its unique role but does not directly