Esophagus

The manuscript aims to include gross anatomical and histological structure of the esophagus. The esophagus is one of the important portions of the digestive system. Definition of the esophagus is, a muscular tube which is extended from the pharynx floor until the stomach. Its function is to transport the food particles from the oropharynx by swallowing operation on way esophageal opening during pharynx to the stomach. Morphology, the esophagus is a long cylindrical structure, which is divided into three segments, the upper portion is called cervical, either intermediate is the thoracic part, and the lower segment is named abdominal, which is attached with the stomach. Muscles of the esophagus are skeletal or striated muscles in the upper segment toward the pharynx, striated and smooth in the middle, either latest segment of the esophagus consists of smooth muscles only. The esophageal structure is different from other types of animals. These differences depend on the nature of food consumption. Histology, the esophagus contains four layers called tunics. First tunics is called the mucosa (epithelia have stratified squamous non-keratin, lamina properia, and muscularis), the next tunics is sub mucosa (connective tissue) with spread to find esophageal glands, either the other two layers are tunica muscularis (outer layer included longitudinal orientation and inner muscles is circular orientations), circular muscle orientation is not clearly circular in each part of the esophagus, but these fibers become more actually at lower parts of the esophagus. Either the muscularis and adventitia (loose connective tissue) without being covered by mesothelium.