<prompt> Not a normal variant of intracranial venous drainage:-Inferior sagittal sinusMedian prosencephalic veinOccipital sinusMarginal sinus  <response>: Abnormal variant: - Median prosencephalic vein: - Formation of vein of Galen got compromised. dt aerio-venous fistula Dural venous sinuses: - Internal cerebral vein draining blood around the brainstem joins with basal vein of Rosenthal to form the great vein of Galen. Great cerebral vein vein of Galen joins with inferior sagittal sinus to form straight sinus, which drain into confluence of sinus. Confluence of sinus - 3 incomings: Mnemonic - SOS draining into confluence anteriorly - straight sinus below - occipital sinus superiorly - superior sagittal sinus This confluence drains into Right left transverse venous sinuses Sigmoid sinuses IJV 