NORMAL ESOPHAGEAL PHYSIOLOGY



The esophagus serves a single function: con­veying solids and liquids from the mouth to the stomach while preventing aspiration and move­ment of gastric contents in the opposite direction (gastroesophageal reflux). Swallowing is a com­plex and well-coordinated motor activity that in­cludes (1) movement of a food bolus into the phar­ynx concomitant with protection of the airway,
(2) relaxation of the upper esophageal sphincter,(3) initiation and distal propagation of peristaltic contractions by the esophageal muscle, and (4) retaxation of the lower esophageal sphincter. After passage of the food bolus, the lower esophageal sphincter reestablishes a tonic contraction, thereby preventing regurgitation of gastric con­tents.