Thoracic aorta is the descending aorta in the posterior mediastinum that supplies the thorax and abdomen.
The thoracic aorta is the portion of the descending aorta located within the thoracic cavity. It begins at the level of the T4 vertebra, where it continues from the aortic arch, and descends through the posterior mediastinum on the left side of the vertebral column. It terminates at the aortic hiatus of the diaphragm at the level of T12, where it continues as the abdominal aorta. The thoracic aorta serves as a major arterial trunk delivering oxygenated blood to the thoracic wall, lungs, esophagus, and upper abdominal structures.
The thoracic aorta lies within the posterior mediastinum and follows a descending path:
Initially, it lies on the left side of the vertebral column but gradually shifts medially to lie directly anterior to the vertebrae by the time it reaches the diaphragm.
The thoracic aorta gives rise to both paired and unpaired branches that supply thoracic organs, the body wall, and diaphragm. The major branches are:
There are typically nine pairs (from T3 to T11). Each artery runs laterally into an intercostal space, located between the innermost and internal intercostal muscles. They supply the thoracic wall and associated musculature. The first two intercostal spaces are supplied by branches of the costocervical trunk, not the aorta.
These are the terminal branches of the thoracic aorta located below the 12th rib, supplying the abdominal wall in the subcostal region.
Typically, there are one right and two left bronchial arteries. These vessels supply the bronchial tree and connective tissue of the lungs, independent of the pulmonary arteries.
Several small branches (usually 4–5) arise from the thoracic aorta to supply the middle third of the esophagus. These arteries anastomose superiorly with esophageal branches of the inferior thyroid artery and inferiorly with branches from the left gastric artery.
Small vessels that supply the posterior aspect of the pericardium.
These arise from the lower portion of the thoracic aorta and supply the superior surface of the diaphragm. They may anastomose with branches from the musculophrenic and pericardiacophrenic arteries.
At the level of T12, the thoracic aorta passes through the aortic hiatus in the diaphragm and becomes the abdominal aorta. The aortic hiatus also transmits the thoracic duct and the azygos vein (sometimes).