The esophagus is approximately 25 cm in length and begins at the level of the C6 vertebra. The external landmark is the cricoid cartilage. It terminates 2–3 cm below the diaphragmatic hiatus, which corresponds to the T11 vertebra.

The esophagus is divided into three parts: cervical, thoracic, and intra-abdominal. The cervical esophagus begins approximately 15 cm from the upper incisors and is approximately 6 cm long. The thoracic esophagus begins approximately 23 cm from the incisors and is approximately 15 cm in length. The intra-abdominal esophagus begins approximately 38 cm from the incisors at the diaphragmatic hiatus and extends for 2–3 cm distally before becoming the gastric cardia.

The thoracic esophagus rests on the thoracic spine and the longus colli muscles. It passes posterior to the trachea, the tracheal bifurcation, the left main stem bronchus, and the left atrium. It descends to the right of the thoracic aorta and moves anterior to the aorta, just above the diaphragm (Figures 18.1a and 18.1b).

The azygos vein lies in front of the bodies of the lower thoracic vertebrae and to the right of the esophagus. At the level of the bifurcation of the trachea, it arches anteriorly to drain into the superior vena cava, just before it enters the pericardium.

The hemiazygos vein passes from the left side of the spine to the right, after crossing the spine and travelling behind the aorta, esophagus, and thoracic duct, to drain into the azygos vein.

The thoracic duct lies between the esophagus, the aorta, and the azygos vein before crossing over, just below the level of the tracheal bifurcation, to the left hemithorax, where it drains into the left subclavian vein.

The esophagus does not have a serosal layer. This increases the risk of anastomotic leaks.

The arterial and venous blood supply and drainage of the esophagus are segmental. The cervical esophagus is supplied by branches of the inferior thyroid artery. The upper thoracic esophagus is supplied by the inferior thyroid artery and an anterior esophagotracheal branch directly from the aorta. The middle and lower esophagus receives its arterial supply directly from the aorta via a bronchoesophageal branch. The lower esophagus and intra-abdominal esophagus portions are supplied by small branches from the left gastric artery and the left inferior phrenic artery.

The parasympathetic innervation of the esophagus is through the vagal nerves. The right and left recurrent laryngeal nerves ascend in the tracheoesophageal groove, giving off branches to both the trachea and the cervical and upper esophagus. The vagal nerves join with the fibers of the sympathetic chain to form the esophageal plexus. Together with the esophagus, the vagi pass through the diaphragm and continue along the lesser curvature of the stomach.

The sympathetic innervation comes from the cervical and thoracic sympathetic chains.