The esophagus is a muscular tube connecting the throat (pharynx) with the stomach. The upper esophageal sphincter (UES) are muscles used when breathing,
eating, belching, and vomiting. They keep food and secretions from going down the windpipe. The lower esophageal sphincter (LES) are muscles
at the low end of the esophagus that meet the stomach. These muscles prevent acid and stomach contents from traveling backward from the stomach.
Disorders that occur when the upper and lower esophageal sprinters are not correctly functioning include, but not limited to:
Acid Reflex/Gastroesophageal Reflux Disease (GERD)