The upper esophageal sphincter is a muscular valve that is located at the upper portion of the esophagus. Unlike the lower esophageal sphincter
, which opens and closes without our conscious effort, the upper esophageal sphincter is under our conscious control. We can control when it opens. For example, we can open the upper esophageal sphincter by swallowing food or liquids.
During swallowing, the upper esophageal sphincter opens to allow food and liquids to pass into the esophagus. It can also reduce the back flow of food and liquids from the esophagus into the pharynx.
Carol Ann Rinzler, Ken DeVault, MD. Heartburn & Reflux for Dummies. Wiley Publishing, Inc., 2004.
Pronunciation: uhp-er ee-sof-uh-jee-uhl sfingk-ter
Also Known As: UES
If the upper esophageal sphincter doesn't function properly, acid that has flowed back into the esophagus is allowed into the throat.