All of the following are pain insensitive structures except
Relatively few cranial structures are pain-producing; these include the scalp, meningeal aeries, dural sinuses, falx cerebri, and proximal segments of the large pial aeries. The ventricular ependyma, choroid plexus, pial veins, and much of the brain parenchyma are not pain-producing. Ref Harrison 20th edition page 85
Choroid plexus
Ventricular ependyma
Brain parenchyma
Falx cerebri
C.N.S