[A rare variation in the zone of the carotid artery]

An extremely rare variation in the angioarchitecture of the carotid arteries consists in the complete missing of the right common carotid artery. The brachiocephalic trunc (innominate artery), forming a bulbus-like extension, branches out into three major stems: internal carotid artery, external carotid artery and the right subclavian artery. The variation is embryologically explainable: The aortic arches III and IV arise together (without ventral aortic root between them) from the persisting initial segment of the right ventral aorta.