The inferior petrosal sinuses, within the human head, are beneath the brain and allow blood to drain from the center of the head.
They drain on either side inferiorly from the cavernous sinus (beneath the brain) and join with the sigmoid sinus to form the internal jugular vein, which continues inferiorly to drain blood from the base of the skull. See diagram (at right): labeled under the brain as "S. PETROS. INF." (for Latin: sinus petrosus inferior).