The thoracic oesophagus within the posterior mediasinum descends from the level of the T4 vertebra to the oesophageal aperture within the diaphragm. During this course, it passes to the median plane by the level of T5 but passes slightly to the left at T7. In its inferior portion, it curves ventrally to traverse the diaphragm at the level of T10.
Its relations during its descent are, sequentially from superior to inferior:
- anterior:
- trachea then tracheal bifurcation and left principal bronchus; tracheobronchial lymph nodes
- right pulmonary artery
- inferior to level of lung roots, left vagus nerve contributes to oesophageal plexus on its surface
- pericardium posterior to right atrium
- posterior:
- vertebral column with longus colli laterally
- right intercostal arteries
- azygous vein and its tributaries from the azygous system; right pleura may be interposed
- inferior to level of lung roots, the right vagus nerve forms a plexus on oesophageal surface
- thoracic duct, inferiorly on the right posterior surface but then ascending to the left at T5
- finally, due to the curve ventrally of the inferior oesophagus, the inferior part of the thoracic aorta comes to lie posteriorly; strong connective tissue connects oesophagus and trachea
- left side:
- left recurrent laryngeal nerve
- thoracic aorta gradually becoming more posterior to the oesophagus during passage inferiorly
- left pleura
- right side: mediastinal pleura in contact but not adherent