Persistent proatlantal intersegmental artery and occipital artery originating from internal carotid artery.

A case of a combined anomaly of persistent hypoglossal and proatlantal intersegmental arteries, proved on arteriogram obtained by the insertion of a needle into the common trunk of both arteries, is presented. In addition, a case of anomalous occipital artery arising from the internal carotid artery associated with an intracranial aneurysm and arteriovenous malformation is presented. Based upon analysis of the persistent proatlantal intersegmental artery and the anomalous occipital artery, we conclude that both arteries have an identical embryological origin.