The esophagus, also known as the esophagus, is located in the middle part of the neck in front of and between the trachea and the spine, and parallel to both. The esophagus is not palpable on the surface of the body. The esophagus, as a part of the human digestive system, is located in the thoracic cavity and is connected to the pharynx at the top, with a total length of about 25 cm. It extends along the thoracic vertebrae all the way down, and the middle and lower part of the esophagus passes through the diaphragm and enters the abdominal cavity and connects with the pancreatic valve. The esophagus is connected to the pharynx at the level of the lower edge of the 6th cervical vertebra, and to the gastric cardia at the left side of the 11th thoracic vertebra. There are three physiologic strictures of the esophagus. The first physiologic stricture is located at the beginning of the esophagus at the level of the inferior border of the 6th cervical vertebra; the second physiologic stricture is located at approximately the level between the 4th and 5th thoracic vertebrae and is formed by the esophagus crossing the posterior aspect of the left main bronchus; and the third physiologic stricture is located at the level of the 10th thoracic vertebrae and is formed by the esophagus crossing the esophageal cleft of the diaphragm.