Arch of aorta: continuation of the ascending aorta, arching over the root of the left lung, continuing as the descending thoracic aorta; lies in the superior mediastinum.
Course
Begins as a continuation of the ascending aorta at the level of the sternal angle, at the right second costal cartilage.
Runs upward, backward and to the left, in front of the tracheal bifurcation, to a summit at the middle of the manubrium sterni.
From the summit it turns backward and downward behind the left bronchus, ending at the lower border of the T4 vertebra, again at sternal angle level, as the descending thoracic aorta.
Ligamentum arteriosum (fibrous remnant of the ductus arteriosus) passes from the origin of the left pulmonary artery to the concavity of the arch.