Which is the delicate innermost membrane enveloping the brain and spinal cord?

• A. Pia Mater
• B. Arachnoid
• C. Dura Mater
• D. Meninges

Answer: (A)

The brain and spinal cord are protected by three membranes called the meninges. The delicate innermost layer that directly covers the neural tissue, following every contour of the brain and spinal cord, is the pia mater. It is thin and vascular, supplying blood to the underlying tissue. Outside it sits the arachnoid mater, which forms the subarachnoid space containing cerebrospinal fluid, and outermost is the dura mater, a tough protective layer. The term meninges refers to all three membranes together, not just the innermost. So the membrane that is both delicate and innermost is the pia mater.