Introduction: the aortic arc is the part of the aorta that is located in the superior mediastinum. It’s the continuation of the ascending aorta which begins posterior to the second right sternocostal joint at the level of the sternal angle of Luis (T4)
Relations: the aortic arch is crossed on the left side by the phrenic and vagus nerves. The left superior intercostal  vein passes forward across the aortic arch superficial to the vagus, deep to the phrenic nerves, to empty into the left brachiocephalic vein.
The left recurrent laryngeal nerve hooks around the ligamentum arteriosum to pass upward to the right side of the aorta in the groove between the trachea and oesophagus. On the right side lie the trachea and oesophagus.
The aortic arch ends by becoming the descending thoracic aorta posterior to the second left sternocostal joint
1. Branchiocephalic trunk
2. The left common carotid artery
3. The left subcalvian artery.
Clinical correlates: in arterial disease associated with aneurysm of the aortic arch pressure may be exerted on the trachea and oesophagus which lie on the right side causing difficulty in swallowing.