Common (CCA) and Internal (ICA) Carotid Artery

Early in the embryogenesis, both primitive proximal external carotid artery (ECA) and internal carotid artery (ICA) arise separately from the third aortic arch: the ECA from its proximal ventral part, and the ICA from the dorsal part. The involution of the third aortic arch involving its segment distal to the origin of the ICA (ductus caroticus) on both left and right sides results in the formation of a common trunk from which develops on each side the common carotid artery (CCA) continuing cranially in the ICA and ECA. In the further evolution, the left CCA is annexed by the developed left fourth aortic arch, and the right CCA becomes a branch of the brachiocephalic trunk (innominate artery) proximal remnant of the distally regressed right fourth aortic arch (Haughton and Rosenbaum 1974).