Anatomical characteristics of two cases of aberrant right subclavian artery.

An aberrant right subclavian artery is a branching variation of the aortic arch. We encountered two female cadavers with an aberrant right subclavian artery during routine student dissection at our school. In both cases, the right subclavian artery was not a branch of the brachiocephalic trunk but originated directly from the distal part of the aortic arch as the last branch and ran between the esophagus and vertebral column, traveling to the upper limb. The right recurrent laryngeal nerve was absent, but a non-recurrent inferior laryngeal nerve branching from the vagus and traveling directly toward the larynx was observed. In the first case, the right and left common carotid arteries originated solely from the aortic arch as the first and second branches, respectively, whereas the right and left common carotid arteries formed a bicarotid trunk at their origin in the second case. A Kommerell diverticulum was present at the base of the aberrant right subclavian artery in the second case, but not in the first case. We analyzed the anatomical differences between the two cases and discussed the developmental aspects and potential clinical risks.