Final answer:
The entrance to the omental bursa is the hepatopancreatic ampulla (ampulla of Vater) located in the duodenal wall. The hepatopancreatic sphincter regulates the flow of bile and pancreatic juice from the ampulla into the duodenum.
Step-by-step explanation:
The entrance to the omental bursa is the hepatopancreatic ampulla, also known as the ampulla of Vater. This structure is located in the duodenal wall where the main pancreatic duct and the bile duct join. The hepatopancreatic sphincter, or sphincter of Oddi, regulates the flow of bile and pancreatic juice from the ampulla into the duodenum.
The entrance to the omental bursa is known as the epiploic foramen (also called the foramen of Winslow). This is a passage that connects the greater sac of the peritoneal cavity and the lesser sac, or omental bursa. The omental bursa lies behind the stomach and the lesser omentum, extending from the lesser curvature of the stomach to the posterior abdominal wall. It's important to note that the omental bursa is separate from the hepatopancreatic ampulla, which is involved in the secretion of bile and pancreatic juice into the duodenum.