Two cases of accessory middle cerebral artery, including one with an aneurysm at its origin

Two cases of accessory middle cerebral artery arising from the internal carotid artery are described, both being demonstrated by carotid angiography. In one case there was an aneurysm at the origin of the anomalous vessel. Only four previous angiographic demonstrations of the anomaly could be found in the literature, although there is a reported post-mortem incidence of 3 per cent.