The Esophagus for the Nonesophagologist

The esophagus is a muscular tube (striated muscle at the top end, smooth muscle in the middle and lower portion) connecting the pharynx and the stomach. It is closed at both the top and bottom ends by specialized muscular sphincters. Deglutition begins as a programmed act, mediated by nerve fibers from the brain stem, and spreads aborally with a wave of inhibition preceding a moving-ring contraction that obliterates the lumen of the esophagus. Fluids fall by gravity in the upright position or are pushed down by the moving ring contraction when the subject is horizontal. There are several factors that prevent constant regurgitation of gastric contents back into the esophagus. Reflux of both gas and liquid does occur as a normal event. The esophagus usually performs its job description of transferring material from the pharynx to the stomach and venting the stomach when necessary with a minimum of fuss.