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What is Which of these is not a tributary of cavernous sinus - and explain in detail?
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)