The primary function of the esophagus is to transport food and liquids from the mouth to the stomach. It is a muscular tube, about 10 inches long in adults, that connects the throat (pharynx) to the stomach. Food is pushed down the esophagus by a series of coordinated muscle contractions known as peristalsis. These contractions occur in a wave-like motion that propels the swallowed material further down. Additionally, the esophagus contains a sphincter at each end— the upper esophageal sphincter to prevent air from entering the digestive tract and the lower esophageal sphincter to control food passage into the stomach.