The esophagus is a fixed fibromuscular tube that forms a part of the upper gastrointestinal tract. Aided by peristaltic contractions, it moves ingested food and liquids from the pharynx to the stomach. Therefore, the esophagus connects the pharynx with the stomach. It is about 10 inches (25 cm) long and approximately 1 inch (2 cm) wide.

The esophagus begins approximately at the level of the sixth cervical vertebra (C6) as the inferior continuation of the laryngopharynx. In the thorax, it travels through the superior and inferior mediastinum behind the trachea and heart. When reaching the diaphragm, the esophagus passes via the esophageal hiatus. It enters the abdominal cavity and ends, continuing as the cardia of the stomach at the level of the eleventh thoracic vertebra (T11).

Overall, the esophagus has three parts, several constrictions and two sphincters.

Parts

The esophagus can be subdivided into three parts based on its location:

Cervical part - extends from the esophageal opening at the level of the inferior border of the cricoid cartilage to the superior thoracic aperture at the level of the first thoracic vertebra (T1); it passes behind the trachea;
Thoracic part - extends from the superior thoracic aperture at the level of the first thoracic vertebra (T1) to the esophageal hiatus of the diaphragm at the level of the tenth thoracic vertebra (T10); this portion passes through the superior mediastinum and posterior mediastinum of the inferior mediastinum; it contains curves and constrictions;
Abdominal part - the final portion that extends between the esophageal hiatus of the diaphragm (T10) and the cardiac orifice of the stomach (T11); it is the shortest part; the peritoneum covers it.

Constrictions

The esophagus has four anatomical constrictions:

Pharyngoesophageal constriction - located at the level of the esophageal opening (C6 level); corresponds to the upper esophageal sphincter;
Aortic constriction - found at the site where the esophagus crosses the aortic arch (T4 level);
Bronchial constriction - located at the site where the esophagus crosses the left main bronchus (T5 level);
Diaphragmatic (phrenic) constriction - found at the site where the esophagus goes through the diaphragm (T10 level).

The anatomical constrictions mentioned above are present in live and dead people, but each person also has several physiological constrictions. They are present only in live people. The first physiological constriction is located below the anatomical bronchial constriction, while the second is situated at the T8 or T9 level, where the esophagus crosses the descending thoracic aorta. The first constriction develops when atrial dilatation occurs, while the second constriction is present in case atherosclerosis affects the aorta.

Sphincters

The esophagus has two sphincters that are found on both its endings. They prevent the backflow of gastric acid in the esophagus, as well as stop air passage to the stomach when digestion is not happening.

The upper sphincter is located between the pharynx and the esophagus. It is composed of striated skeletal muscle fibers. This sphincter is an anatomical sphincter.
The second is the lower sphincter. It is more of a physiological sphincter located between the stomach and the esophagus. The lower esophageal sphincter contains smooth muscle fibers.

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Esophagus