This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
Which of these is not a tributary of cavernous sinus - 
Select and explain. 
A. Sphenoparietal sinus, B. Superior petrosal sinus, C. Superficial middle cerebral vein, D. Inferior ophthalmic vein
B: Superior petrosal sinus
Answer: B: Superior petrosal sinus 
Explanation: 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)