Aortic arch

Rajat Das Gupta

Source	ascending aorta
Branches	brachiocephalic artery, left common carotid artery, left subclavian artery
Precursor	fourth aortic arch

The arch of the aorta or the transverse aorta is the part of the aorta that begins at the level of the upper border of the second sternocostal articulation of the right side, and runs at first upward, backward, and to the left in front of the trachea; it is then directed backward on the left side of the trachea and finally passes downward on the left side of the body of the fourth thoracic vertebra, at the lower border of which it becomes continuous with the descending aorta.
It thus forms two curvatures: one with its convexity upward, the other with its convexity forward and to the left. Its upper border is usually about 2.5 cm. below the superior border to the manubrium sterni.
It lies within the mediastinum.

Related structures

The ligamentum arteriosum connects the commencement of the left pulmonary artery to the aortic arch. The blood bypasses the lungs through the ductus arteriosus during embryonic circulation. This becomes the ligamentum arteriosum postnatal as pulmonary circulation begins.
The aortic knob is the prominent shadow of the aortic arch on a frontal chest radiograph.

 Diagram showing the origins of the main branches of the carotid arteries.

Front view of heart and lungs.

Heart left lateral view