Esophagus, << ee SOF uh guhs, >> also called gullet, is the muscular tube that carries food from the mouth to the stomach. The muscles in the walls of the esophagus contract in a wavelike manner, moving the food down to the stomach. Glands in the walls of the esophagus secrete mucus that helps the movement of food by providing lubrication.
A muscular ring called the lower esophageal sphincter surrounds the opening between the esophagus and the stomach. The sphincter normally keeps the stomach contents from flowing back into the esophagus. The stomach produces a digestive juice that contains a strong acid called hydrochloric acid. If the sphincter fails to function properly, stomach acid may rise back into the esophagus, causing a painful burning sensation called heartburn. The acid may damage the esophagus, leaving open sores in its lining.
The human esophagus is about 10 inches (25 centimeters) long. The length varies greatly in different animals. The esophagus of fish is short, while that of giraffes is extremely long. Many birds have a saclike part of the esophagus called the crop for the temporary storage of food.
