The esophagus is the muscular tube that conveys food from the back of the throat to the stomach. It is located in the chest behind the sternum and the trachea, the main breathing tube leading to the lungs. The esophagus joins the stomach at the diaphragm, which is the breathing muscle separating the chest and lungs from the abdomen. The connection of the esophagus to the stomach at the diaphragm is called the gastro-esophageal junction. The gastro-esophageal junction serves as a one-way valve to keep stomach contents from being refluxed or regurgitated back into the esophagus.