Prominent development of the inferolateral trunk of the internal carotid artery as a collateral pathway to the external carotid system.

The development of anastomosis between the inferolateral trunk of the internal carotid artery and the artery of the foramen rotundum of the internal maxillary artery is ascribed to a variety of embryologic vascular channels between the internal and external carotid systems [1] , which is thought to be phylogenetically compatible with the rete mirabile in other vertebrates [2]. We describe the angiographic features of such an anastomosis discovered incidentally 29 years after external carotid ligation.