Which meninges layer is closest to the brain surface?

• A. Pia mater
• B. Dura mater
• C. Arachnoid mater
• D. Choroid plexus

Answer: (A)

The meninges are three protective coverings that envelope the brain, arranged from outermost to innermost as dura mater, arachnoid mater, and pia mater. The closest layer to the brain surface is the pia mater—a very thin, delicate membrane that tightly adheres to the brain, following every contour of the gyri and sulci. It sits just inside the subarachnoid space, which contains cerebrospinal fluid and small blood vessels that nourish brain tissue. The arachnoid mater lies outside this layer, forming the middle meninx, while the dura mater is the tough outer layer. The choroid plexus isn’t a meningeal layer at all; it’s tissue within the ventricles that makes CSF.