<prompt> Which of these is not a tributary of cavernous sinus -Sphenoparietal sinusSuperior petrosal sinusSuperficial middle cerebral veinInferior ophthalmic vein  <response>: Superior petrosal sinus is a draining channel not a tributary of the cavernous sinus. Tributaries incoming channels of the cavernous sinusSuperior ophthalmic veinA branch of an inferior ophthalmic vein or sometimes vein itselfCentral vein of the retina it may also drain into a superior ophthalmic veinSuperficial middle cerebral veinInferior cerebral veinSphenoparietal sinusFrontal trunk of middle meningeal vein it may also drain into pterygoid plexus or into sphenoparietal sinus 