The esophageal sphincter is a ring of muscle at the top and bottom of the esophagus that controls the passage / transit of food and liquid into the stomach and prevents stomach contents from flowing back into the esophagus.
The esophageal sphincter is a ring of muscle at the top and bottom of the esophagus that controls the passage / transit of food and liquid into the stomach and prevents stomach contents from flowing back into the esophagus.