<P> CSF returns to the vascular system by entering the dural venous sinuses via arachnoid granulations . These are outpouchings of the arachnoid mater into the venous sinuses around the brain , with valves to ensure one - way drainage . This occurs because of a pressure difference between the arachnoid mater and venous sinuses . CSF has also been seen to drain into lymphatic vessels , particularly those surrounding the nose via drainage along the olfactory nerve through the cribriform plate . The pathway and extent are currently not known , but may involve CSF flow along some cranial nerves and be more prominent in the neonate . CSF turns over at a rate of three to four times a day . CSF has also been seen to be reabsorbed through the sheathes of cranial and spinal nerve sheathes , and through the ependyma . </P>
the csf returns to the bloodstream by way of
the dural venous sinuses via arachnoid granulations