The esophagus is the muscular tube that is located between the pharynx and the stomach that aids in digestion during swallowing.
Formation and Orientation
The esophagus is composed of four separate layers; the mucosa, submucosa, muscularis externa and the adventitia.
The mucosa includes the stratified squamous epithelium, lamina propria and muscularis mucosae. The submucosa houses the esophageal glands and connective papillae. The muscularis externa is composed of three sublayers The upper third layer is purely striated muscle while the middle third is striated and smooth muscle, and the inferior third is mainly smooth muscle.
As most organs do, the esophagus has its limitations in its levels. Its first constriction is the esophageal inlet. Its second level is where its outer wall is crossed by the aortic arch and lastly where it meets the diaphragm.
The esophagus works as a tunnel used for transportation of food and liquid to the rest of the digestive tract.
Image Caption: Esophagus. Credit: Wikipedia