Petrobasal Vein: A Previously Unrecognized Vein Directly Connecting the Superior Petrosal Sinus with the Emissary Vein of the Foramen Ovale.

The petrobasal vein, an unknown vein directly connecting the superior petrosal sinus and the emissary veins of the foramen ovale and draining into the pterygoid plexus, can occasionally be identified on cerebral angiography as a variant drainage route from the cerebellum and brainstem veins and/or from the superficial middle cerebral vein. The petrobasal vein is thought to be a remnant of the primitive tentorial sinus.