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 stays 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).
eMedicineHealth Medical Reference from Healthwise
To learn more visit Healthwise.org
© 1995-2014 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.
- Personalized Tips for Managing Migraine
- Do You Take Good Care of Your Eyes?
- Tips for a Clean Home & Healthy Cat