The act of swallowing initiates a chain of events that results in transport of ingested material from the mouth to the stomach. The events constitute orderly contractions of muscles of the pharynx and esophagus and relaxation at the ends of the esophagus. The entrances to the esophagus at each end are closed at rest to prevent passage of material into the esophagus between swallows. Description of the events within the pharynx and esophagus during and between swallows will be found in other reviews,1-3 as well as in other articles of this symposium. The purpose of this report is to discuss some of the factors that may be responsible for the organization and control of peristalsis and sphincteric action.
ANATOMICAL CONSIDERATIONS Pharynx and Upper Esophageal Sphincter
Discrete muscle bundles can be identified in the pharynx and upper esophageal sphincter (UES). These bundles surround the pharynx and interlace and overlap to