The sphincter between the stomach and duodenum is:
a. The pyloric sphincter
b. The gastroesophageal sphincter
c. The hepatopancreatic sphincter
d. The ileocecal valve

Verified step by step guidance

1. Step 1: Understand the anatomical locations involved. The stomach connects to the duodenum, which is the first part of the small intestine, so the sphincter in question controls the passage of stomach contents into the duodenum.
2. Step 2: Review the function and location of each option: (a) The pyloric sphincter regulates the passage from the stomach to the duodenum; (b) The gastroesophageal sphincter controls the passage between the esophagus and stomach; (c) The hepatopancreatic sphincter controls the flow of bile and pancreatic juice into the duodenum; (d) The ileocecal valve controls flow between the small intestine and large intestine.
3. Step 3: Identify which sphincter specifically lies between the stomach and duodenum by matching the anatomical connection and function.
4. Step 4: Confirm that the correct sphincter prevents backflow and regulates the release of stomach contents into the duodenum, which is characteristic of the pyloric sphincter.
5. Step 5: Conclude that the sphincter between the stomach and duodenum is the pyloric sphincter, corresponding to option (a).

Key Concepts

Pyloric Sphincter

The pyloric sphincter is a muscular valve located between the stomach and the duodenum. It regulates the passage of partially digested food (chyme) from the stomach into the small intestine, preventing backflow and controlling digestion speed.

Gastroesophageal Sphincter

The gastroesophageal sphincter, also known as the lower esophageal sphincter, is a ring of muscle at the junction of the esophagus and stomach. It prevents acidic stomach contents from refluxing back into the esophagus, protecting the esophageal lining.

Hepatopancreatic Sphincter and Ileocecal Valve

The hepatopancreatic sphincter controls the flow of bile and pancreatic juices into the duodenum, aiding digestion. The ileocecal valve is located between the small and large intestines, preventing backflow from the large intestine. Neither is located between the stomach and duodenum.