Esophagus
The esophagus commonly called the food pipe is a muscular tube that connects the throat or the pharynx with that of the stomach. The average esophagus is about 8 inches long, and is lined mucosa which is a moist pink tissue. The esophagus lies just behind the windpipe or the trachea and the heart, and also lies in front of the spine. Just prior to entering the stomach, the esophagus cross pass through the diaphragm. The upper esophageal sphincter lies under the conscious control, that is used during the processes of breathing, eating, belching, and vomiting. They are responsible for keeping the food and secretions from going down the windpipe. The lower esophageal sphincter (LES) prevents the acid and the stomach contents from retreating backwards from the stomach. The muscles of the LES are not under the voluntary control of a human being, they are controlled by the nervous system.