Variations in the drainage of the basal vein.
D002560:Cerebrovascular Circulation; D003392:Cranial Sinuses / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000196:embryology; D004388:Dura Mater / Q000098:blood supply; D006801:Humans; D008636:Mesencephalon / Q000098:blood supply; D010690:Phlebography; D013687:Telencephalon / Q000098:blood supply