- The thoracic aorta is a tubular structure that is divided into 5 segments (level 1–5):
Aortic root: from the aortic valve (AV) to the sinotubular junction (STJ)
Ascending aorta: STJ to innominate artery
Aortic arch: innominate artery to left subclavian artery (LSCA)
Descending thoracic aorta: LSCA to diaphragm
Abdominal aorta: below diaphragm
The ascending aorta has an average length of 7–11 cm, arch 2.2–3.6 cm, and the descending aorta 20–30 cm.
Normal aortic diameter varies with the measurement method (US, CT, MRI), age, sex, BSA, and the location, but typically it is up to 35 mm (±2 mm).
The aortic wall is 1–2 mm thick and comprises 3 layers: thin adventitia, elastic media, and a smooth intima (see p. 205).