n :  either of two venous sinuses on each side of the base of the brain:  a  :  a small superior sinus that connects the cavernous and transverse sinuses of the same side - called also superior petrosal sinus   b  :  a larger inferior sinus that is situated in a sulcus on each side formed by the junction of the petrous portion of the temporal bone and the basilar portion of the occipital bone and that extends from the posterior inferior end of the cavernous sinus through the jugular foramen to join the internal jugular vein of the same side - called also inferior petrosal sinus  .
 
 
 
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