The aorta distributes oxygenated blood to all parts of the body through the systemic circulation.

[6]: 18 The ascending aorta begins at the opening of the aortic valve in the left ventricle of the heart.

In addition to these blood vessels, the aortic arch crosses the left main bronchus.

The left vagus nerve, which passes anterior to the aortic arch, gives off a major branch, the recurrent laryngeal nerve, which loops under the aortic arch just lateral to the ligamentum arteriosum.

The aortic arch ends, and the descending aorta begins at the level of the intervertebral disc between the fourth and fifth thoracic vertebrae.

[9]: 195 The abdominal aorta begins at the aortic hiatus of the diaphragm at the level of the twelfth thoracic vertebra.

[9]: 331 The ascending aorta develops from the outflow tract, which initially starts as a single tube connecting the heart with the aortic arches (which will form the great arteries) in early development but is then separated into the aorta and the pulmonary trunk.

A failure of the aorticopulmonary septum to divide the great vessels results in persistent truncus arteriosus.

Within the tunica media, smooth muscle and the extracellular matrix are quantitatively the largest components, these are arranged concentrically as musculoelastic layers (the elastic lamella) in mammals.

The smooth muscle component, while contractile, does not substantially alter the diameter of the aorta,[15] but rather serves to increase the stiffness and viscoelasticity of the aortic wall when activated.

The contraction of the heart during systole is responsible for ejection and creates a (pulse) wave that is propagated down the aorta, into the arterial tree.

The stiffness of the aorta is associated with a number of diseases and pathologies, and noninvasive measures of the pulse wave velocity are an independent indicator of hypertension.

Measuring the pulse wave velocity (invasively and non-invasively) is a means of determining arterial stiffness.

This stretching gives the potential energy that will help maintain blood pressure during diastole, as during this time the aorta contracts passively.

[19][20][21] All amniotes have a broadly similar arrangement to that of humans, albeit with a number of individual variations.

[26] The function of the aorta is documented in the Talmud, where it is noted as one of three major vessels entering or leaving the heart, and where perforation is linked to death.