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Esophagus

Esophagus is a muscular about 10 inches long. It is continuous above with the laryngeal part of the pharynx and below with the stomach. It begins at the level of sixth cervical vertebra and ends at the level of tenth thoracic vertebra.

For descriptive purposes, the esophagus is divided into three regions as explained below.

Esophagus in the region of neck:

In the neck, the esophagus lies in from of the vertebral column and is related to the lobes of thyroid gland laterally. Anterior to it lies the trachea, with which it is in contact. The recurrent laryngeal nerves also lie anterior to it.

Esophagus in the region of thorax:

In the thorax, the esophagus passes downward and to the left the superior and then the posterior mediastinum. At the level of the sternal angle, the arch of aorta pushes the esophagus to the midline. It is related to the following structures in the region of thorax.

Anterior relations:

  • Trachea
  • Left recurrent laryngeal nerve
  • Left principal bronchus (which constricts the esophagus)
  • Pericardium (which separates the esophagus from the left atrium)

Posterior relations:

  • Bodies of thoracic vertebrae
  • Thoracic duct
  • Azygous vein
  • Right posterior intercostal arteries
  • Descending thoracic aorta (at the lower end of esophagus)

Right side:

  • Mediastinal pleura
  • Terminal part of azygous vein

Left side:

  • Left subclavian artery
  • Aortic arch
  • Thoracic duct
  • Mediastinal pleura

Esophagus in the region of abdomen:

The esophagus enters the abdomen through an opening in the right crus of the diaphragm. After traveling for about half inch in the abdomen, it enters the stomach on its right side. In this region, the esophagus is related anteriorly to the posterior surface of left lobe of liver and posteriorly to the left crus of diaphragm.  The left and right vagi lie on its anterior and posterior surfaces respectively.

Blood supply of esophagus:

Arteries:

The upper third of the esophagus, which lies in the region of the neck, is supplied by the inferior thyroid artery. The middle third, which lies in the thorax, is supplies by the branches from the descending thoracic aorta.  And the lower third, which lies in the abdomen, is supplies by the left gastric artery.

Veins:

The veins from the upper third portion join the inferior thyroid veins, from the middle third join the azygous vein and from the lower third join the left gastric vein (tributary of the portal vein).

Lymph drainage of esophagus:

As is the case with the blood supply, the lymph drainage is also different for the three parts of esophagus. The lymphatics from the upper third of esophagus drain into the deep cervical nodes. Those from the middle third drain into the superior and posterior Mediastinal nodes and the lymphatics from the lower third drain into the celiac nodes.

Nerve supply to esophagus:

The esophagus receives nerve fibers from both sympathetic and parasympathetic nervous systems. The parasympathetic fibers are supplied via the right and left vagus nerves. The sympathetic fibers (both efferent and afferent) are supplied through the sympathetic trunks.

Functions of esophagus:

Esophagus is a mere tube that connects the larynx with the stomach. It is acts as a passage between the two structures, so that the food can reach the stomach. The lower end of esophagus has well developed circular muscle fibers, which act as a physiologic sphincter to prevent the regurgitation of food from the stomach.