A unique variation with five branches of the aortic arch.

Here, we present a unique case with 5 branches of the aortic arch (AA), namely the right common carotid artery, left common carotid artery, left thyrocervical trunk, left subclavian artery and right subclavian artery (RSA), from right to left. We found that the left thyrocervical trunk originated directly from the AA rather than the left subclavian artery. In addition, the RSA arose dorsally as the last branch of the AA and passed posteriorly to the oesophagus to supply the right upper limb. In addition, the right vertebral artery originated from the right common carotid artery instead of the RSA. Despite numerous studies on AA variations, to our knowledge, this is the first case of the left thyrocervical trunk originating directly from the AA and the RSA arising dorsally as the last branch of a 5-branch AA. Our case provides useful information to anatomists, radiologists and neck and thoracic surgeons.