The esophagus is a muscular tube, usually between 10 and 13 inches long, that runs through the neck and upper chest connecting the mouth to the stomach. Through a process called peristalsis (involuntary wave-like muscular contractions), the esophagus moves food and liquids from the mouth to the stomach, where they are digested and broken down before passing into the intestines.
The esophagus is lined with a special mucous membrane that protects it from the constant passage of food. This membrane is made up of flat, thin cells, known as squamous cells.
At the bottom of the esophagus, the lower esophageal sphincter – a ring-like muscle that serves as a one-way valve – allows food to pass into the stomach while preventing chyme (a mixture of food, stomach acid, and digestive enzymes) from traveling back up the esophagus.
When the sphincter becomes weak or fails completely, acidic chyme is no longer prevented from entering the esophagus, which can cause a painful and potentially dangerous condition known as gastroesophageal reflux disease (GERD). Over time, GERD can lead to a pre-cancerous condition called Barrett’s Esophagus.