By definition, peristalsis is the waves of contraction seen in tubelike organs; propels substances along the tract. Though peristalsis is confined only to the esophagus, it is necessary to understand the beginnings of food, before it enters the esophagus. After mastication occurs, food enters the pharynx. The Pharynx is the passageway through which many tubes run from the mouth and the nose to the upper body. Some of these tubes are the nasopharynx, which runs oxygen to the lungs, and the oropharynx, which also runs oxygen to the lungs. Masticated food is not passed to the longs by the actions of the epiglottis. The epiglottis is a membrane, which covers the entrance to the nasopharynx. By covering the entrance to the nasopharynx, food is forced to enter the esophagus.

After food passes through the pharynx, it enters the esophagus. The esophagus, also known as the gullet, runs from the pharynx to the diaphragm, to the top of the stomach. The Esophagus is about 25 cm (10 inches). The esophagus is really a large muscle, which pushes food down to the stomach. The walls of the esophagus are lined with four layers of thin tissue. These membranes are the mucosa, the submucosa, the muscularis externa, and the serosa.

The mucosa is the inner most layer. It is a moist membrane that lines the cavity of the esophagus. The mucosa consists of a small amount of connective tissue as well as the surface epithelium. The mucosa is also lined with a very thin layer of smooth muscle tissue. After the esophagus ends, the mucosa continues, but is extended by a friction resisting membrane of stratified squamos epithelium layer.

The submucosa is the second layer of tissue, which lies within the esophagus. The submucosa is a soft connective tissue layer. The submucosa contains lymph nodules, nerve endings, lymphatic vessels, and blood vessels.

The muscularis externa lies within both the submucosa as well as the mucosa. The muscularis externa is mainly constituted of two different types of smooth muscle cells. The muscularis externa is made of the longitudinal layer of smooth muscle cell as well as the circular layer of smooth muscle cell.

The final layer of tissue within the esophagus is the serosa. The serosa is the innermost layer of tissue within the esophagus. The serosa is made up of a single flat layer of serous fluid producing cells. There are two serous fluid producing cells types, the visceral peritoneum as well as the parietal peritoneum.