First Time User? Enroll now.
COVID-19: Vaccine information and additional resources | Medicaid: The program is changing and you must take steps to keep your UNC Health providers
Home > Health Library > 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).
Current as of: February 10, 2021
Author: Healthwise Staff
Medical Review:Adam Husney MD - Family Medicine & Peter J. Kahrilas MD - Gastroenterology
To learn more about Healthwise, visit Healthwise.org.
© 1995-2021 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.
300 Ashville Ave.
Cary, NC 27518
3100 Duraleigh Road
Raleigh, NC 27612
4207 Lake Boone Trail
Raleigh, NC 27607
10208 Cerny St.
Raleigh, NC 27617
1505 SW Cary Parkway
REX Healthcare of Cary, Suite 302
Cary, NC 27511