An aberrant right subclavian artery is the most common of the aortic arch anomalies, and is asymptomatic. Instead of being the first branch (with right common carotid as the brachiocephalic artery) it arises on its own as the fourth branch, after the left subclavian artery. It then hooks back to reach the right side. Its relationship to the oesophagus is variable:
– 80% behind
– 15% between oesophagus and trachea
– 5% anterior to the trachea

As can be expected from embryology, the right recurrent laryngeal nerve is often absent.

Reference: Weisleder. Primer of Diagnostic Imaging
Image courtesy of Dr. Behrang Amini,
Credit: Dr Frank Gaillard