During the dissection of the neck region of a 56 year old female cadaver an artery was found branching from the thyrocervical trunk as a fourth branch and entering the aortic arch on its superior posterior aspect between the brachiocephalic trunk and the left common carotid artery. Selective angiography revealed that this artery branched into several arterioles at its junction on the superior aspect of the aortic arch between the brachiocephalic trunk and the left common carotid artery. No similar structure could be found in the literature. Evaluation of this phenomenon according to our knowledge of the development of human arterial networks, it was concluded that the artery might be a persistent intersegmental artery, or an enlarged nutrient artery (vas vasorum) to the aortic arch. © 1995, Gustav Fischer Verlag Jena GmbH. All rights reserved.