Post-mortem anatomical study on the "Tentorial sinus", in 23 skulls, using a retrograde veinous injection of a mixture of Rhodopas and lead tetroxide. Present in more than half the cases, this sinus actually constitutes a true sinus, principally draining the superior and inferior hemispheric veins of the cerebellum, traversing the posterior section of the tentorium cerebelli and opening into the lateral or straight sinus.