<prompt> Great vein of Galen is formed byTwo internal cerebral veinsSuperficial middle cerebral vein deep middle cerebral veinAnterior cerebral vein basal veinInternal cerebral veins straight sinus  <response>: A Two internal cerebral veins GALENS VEINS: The internal cerebral veins; the great vein of Galen is formed by their union. Anterior cerebral vein also known as Galens vein. Great cerebral vein or Great vein of Galen is formed by union of two internal cerebral veins. It terminates in the straight sinus. 