This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.N.S, Subject name: Medicine
Pain insensitive structure 
Select and explain. 
A. Middle cerebral aery, B. Choroid plexus, C. Dural sheath, D. Falx cerebri
B: Choroid plexus
Answer: B: Choroid plexus 
Explanation: The cranium, brain parenchyma, ependymal lining of the ventricles, and choroid plexus are all pain insensitive Ref Harrison20th edition pg 2345