Which of these is not a tributary of cavernous sinus -

Superior petrosal sinus is a draining channel (not a tributary) of the cavernous sinus. Tributaries (incoming channels) of the cavernous sinus Superior ophthalmic vein A branch of an inferior ophthalmic vein or sometimes vein itself Central vein of the retina (it may also drain into a superior ophthalmic vein) Superficial middle cerebral vein Inferior cerebral vein Sphenoparietal sinus Frontal trunk of middle meningeal vein (it may also drain into pterygoid plexus or into sphenoparietal sinus)