Muscular tube that conveys food by peristalsis from the pharynx to the stomach .
Both ends are closed off by sphincters (muscular constrictions), which relax to let food through and close to keep it from backing up. Disorders include ulceration and bleeding, heartburn from stomach acid, achalasia (failure of one or both sphincters to open), and muscle spasms. Scleroderma may involve the esophagus.