Definition: the thoracic aorta is the continuation of the aortic arch.
Origin: it begins on the left side of the inferior border of the 4th thoracic vertebra.
Course: the descending thoracic aorta descends in the posterior mediastinum on the left side of T4, to T12. As it descends it approaches the median plane and displaces the esophagus to the right. It then terminates anterior to the vertebral column at the inferior border of T12 vertebra where it enters the abdomen through the aortic hiatus to become the abdominal aorta.
Anterior: root of the left lung, the pericardium and the esophagus.
posterior: fourth to twelfth thoracic vertebra
right: thoracic duct and azygos vein
1. Bronchial arteries
2. Esophageal branches
3. Pericardial branches
4. Mediastinal branches
5. Posterior intercostal arteries
6. Subcostal arteries
7. Superior phrenic arteries