The thoracic aorta is divided into 3 sections:
- Ascending aorta (Pars ascendens aortae)
- Aortic arch (Arcus aortae)
- Descending aorta (Pars descendens aortae)
1. The ascending aorta gives off the two coronary arteries (Aa. coronariae dextra et sinistra), which supply the heart.
2. From the aortic arch the right common carotid artery and the right subclavian artery arise from a short common trunk (truncus brachiocephalicus). These are followed by the left common carotid artery and the left subclavian artery. In about 10% of cases, an A. thyroidea ima to the thyroid gland arises from the aortic arch or truncus brachiocephalicus. There are several further anatomical variants, e.g. A. lusoria or truncus bovinus.
3. The descending aorta gives off parietal branches to the thorax and visceral branches to the viscera:
a) Parietal branches:
- Aa. intercostales posteriores, 9 arteries to the intercostal spaces (the first two arise from the truncus costocervicalis). After giving off a R. dorsalis with muscular and cutaneous branches (R. cutaneus medialis and lateralis) to the back and a R. spinalis for the spinal canal, they run between the vein and the intercostal nerve ("VAN") at the lower border of the rib within the sulcus costae, between the intercostal muscles. At the costal angle, the R. collateralis descends to the upper border of the next lower rib. After giving off the Rr. cutanei laterales with Rr. mammarii laterales, the intercostal arteries anastomose with the Rr. intercostales anteriores of the A. thoracica interna.
- A. subcostalis: The last of the intercostal arteries lies beneath the 12th rib.
- A. phrenica superior: small branches to the pars lumbalis of the diaphragm.
Usually one of the Aa. radiculares medullares is dominant, the so-called Adamkiewicz artery (usually Th 11-12).
b) Visceral branches:
- Rr. bronchiales to the bronchi: The right vessel often arises from the A. intercostalis III.
- Rr. oesophageales: 3–6 branches to the oesophagus
- Rr. mediastinales: small branches to the lymph nodes in the posterior mediastinum as well as to the pericardium (Rr. pericardiaci)