Complex anomalies of the human aortic arch system: unique case with both vertebral arteries as additional branches of the aortic arch.

We describe a case of an aortic arch with five primary branches arising in a sequence that has previously never been reported. From right to left, the brachiocephalic trunk and left common carotid, left vertebral, and subclavian arteries originated from the convexity of the aortic arch. The last branch was the right vertebral artery that arose from the dorsal aspect of the aortic arch opposite the ligamentum arteriosum. Presenting a dilatation at its commencement, the right vertebral ran to the right behind the esophagus and entered the foramen transversarium of the seventh cervical vertebra, whereas the left vertebral passed to the foramen transversarium of the fifth cervical vertebra. The left vertebral artery gave off the left thyroid artery; a thyrocervical trunk was absent on the left side. A thyroidea ima arose from the brachiocephalic trunk. The embryology of this complex anomaly as well as its potential clinical significance are discussed.