Sphincter mechanisms at the esophago-gastric junction

Abstract

Understanding of the sphincter mechanism at the esophago-gastric junction (EGJ) is crucial to the understanding of esophageal motor disorders and gastroesophageal reflux disease. Smooth muscles of the lower end of esophagus (LES) and skeletal muscles of crural diaphragm are the key components of sphincter mechanism at the EGJ. Basal LES tone/contraction is partly myogenic and party neurogenic. LES relaxation is mediated via the vagus nerve, which activates inhibitory motor neurons located in the esophageal wall. Longitudinal muscle contraction of the esophagus appears to play a critical role in the LES relaxation. LES and crural diaphragm relax together during transient LES relaxation (TLESR), which is the major mechanism of gastroesophageal reflux. TLESR is also important during belching, vomiting, and rumination. A large number of pharmacological agents decrease the TLESR frequency and could be potentially useful in the treatment of reflux disease. High-resolution and high-definition manometry has and will continue to improve our understanding of the complex functioning of EGJ.