Descending thoracic aorta

The descending thoracic aorta (Latin: aorta thoracica, pars thoracica aortae) is the portion of the descending aorta located within the thorax. It is the continuation of the aortic arch, travels through the posterior mediastinum and becomes the abdominal aorta, when it enters the abdomen. The descending thoracic aorta gives off branches to the pericardium, lungs, diaphragm and other important structures, mainly within the thorax.

Course of descending thoracic aorta

The thoracic part of the descending aorta begins at the lower edge of the 4th thoracic vertebra (T4) as the continuation of the aortic arch. The thoracic aorta descends through the posterior mediastinum. It ends anterior to the lower edge of the 12th thoracic vertebra (T12), where it enters the abdomen via the aortic hiatus of the diaphragm. After entering the abdominal cavity, it continues downward as the abdominal aorta.

Superiorly, the descending thoracic aorta is situated to the left of the spine. As the aorta descends, it approaches the midline, and its inferior portion then lies directly anterior to the lower thoracic vertebral bodies.

Branches of descending thoracic aorta

On its course, the descending thoracic aorta gives off a number of branches, which may be grouped into two categories: visceral branches - to the internal thoracic organs, and parietal branches that supply the thoracic muscles. The main visceral branches of the descending thoracic aorta are as follows:

• Pericardial branches - supply the dorsal portion of the pericardium;
• Bronchial branches (or bronchial arteries) - supply the lungs;
• Esophageal branches - supply the esophagus;
• Mediastinal branches - supply lymph nodes and other tissue in the posterior mediastinum.

The parietal branches of the descending thoracic aorta include the following blood vessels:

• Posterior intercostal arteries - supply the intercostal spaces;
• Subcostal artery - mainly supplies the flat muscles of the abdominal wall;
• Superior phrenic arteries - supply the diaphragm and adrenal glands.