The arch of the aorta (aorticarch), the curved continuation of the ascending aorta, begins posterior to the 2nd right sternocostal
joint at the level of the sternal angle. It arches superiorly, posteriorly and
to the left, and then inferiorly. The arch ascends anterior to the right
pulmonary artery and the bifurcation of the trachea, reaching its apex at the
left side of the trachea and esophagus as it passes over the root of the left
lung. The arch descends posterior to the left root of the lung beside the T4 vertebra. The arch ends by becoming the thoracic (descending) aorta posterior
to the 2nd left sternocostal joint.