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Lower esophageal sphincter (LES)

Lower esophageal sphincter (LES)

The lower esophageal sphincter (LES) is a ring of muscle that forms a valve at the lower end of the esophagus, where it joins the stomach.

The LES remains closed except during swallowing, when it allows food to pass from the esophagus into the stomach. When the LES is closed, it prevents the backflow (reflux) of stomach acid into the esophagus. If the LES does not close tightly enough, stomach acid backs up into the esophagus, causing heartburn. A weak lower esophageal sphincter is a major cause of gastroesophageal reflux disease (GERD).

Credits

AuthorJeannette Curtis
AuthorCaroline Rea, RN, BS, MS
EditorKathleen M. Ariss, MS
EditorSusan Van Houten, RN, BSN, MBA
Associate EditorTracy Landauer
Associate EditorPat Truman, MATC
Primary Medical ReviewerPatrice Burgess, MD - Family Medicine
Primary Medical ReviewerAdam Husney, MD - Family Medicine
Primary Medical ReviewerKathleen Romito, MD - Family Medicine
Last UpdatedMay 25, 2007

Author: Jeannette Curtis
Caroline Rea, RN, BS, MS
Last Updated: May 25, 2007
Medical Review: Patrice Burgess, MD - Family Medicine
Adam Husney, MD - Family Medicine
Kathleen Romito, MD - Family Medicine

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