Inferior petrosal sinus
The inferior petrosal sinuses drain on either side inferiorly from the cavernous sinus and join with the sigmoid sinus to form the internal jugular vein, which continues inferiorly.
The inferior petrosal sinus is situated in the inferior petrosal sulcus, formed by the junction of the petrous part of the temporal bone with the basilar part of the occipital bone.
It begins in the postero-inferior part of the cavernous sinus and, passing through the anterior part of the jugular foramen, ends in the superior bulb of the internal jugular vein.
The inferior petrosal sinus receives the internal auditory veins and also veins from the medulla oblongata, pons, and under surface of the cerebellum.
The inferior petrosal sinus is where the pituitary gland drains.
see inferior petrosal sinus sampling