It passes obliquely upward, forward, and to the right, in the direction of the heart's axis, as high as the upper border of the second right costal cartilage, describing a slight curve in its course, and being situated, about 6 centimetres (2.4 in) behind the posterior surface of the sternum.

The upper limit of standard reference range of the ascending aorta may be up to 4.3 cm among large, elderly individuals.

[5] At the union of the ascending aorta with the aortic arch the caliber of the vessel is increased, owing to a bulging of its right wall.

The ascending aorta is covered at its commencement by the trunk of the pulmonary artery and the right auricula, and, higher up, is separated from the sternum by the pericardium, the right pleura, the anterior margin of the right lung, some loose areolar tissue, and the remains of the thymus; posteriorly, it rests upon the left atrium and right pulmonary artery.

[7] Diagnostic methods such as echocardiography, magnetic resonance imaging (MRI) and computed tomography (CT) scans, often with contrast enhancement, are used in the detection of pathology and evaluation of ascending aorta.