Which is the thick, outermost layer of the meninges surrounding and protecting the brain and spinal cord?

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

Answer: (B)

The outermost protective covering is the dura mater, a thick, tough membrane that enfolds the brain and spinal cord. It’s the strongest of the three meninges, providing substantial protection and support. In the skull it has an outer layer that adheres to the bone and an inner layer that helps form partitions to support the brain and house venous sinuses. Beneath the dura mater lie the arachnoid and the pia mater, which are progressively thinner and more delicate, with the arachnoid just under the dura and the pia mater closely following the contours of the brain and spinal cord. Since the question asks for the thick outermost layer, dura mater is the correct choice.