The toughest, outermost layer of the meninges is the:

• A. Arachnoid mater
• B. Dura mater
• C. Pia mater
• D. Subdural space

Answer: (B)

The outermost protective layer around the brain is the dura mater. It is a thick, tough, fibrous membrane that sits just inside the skull and acts as the main safeguard of the brain and spinal cord. The dura often has two sublayers—one attaching to the inner skull surface and another folding inward to form partitions that help stabilize and support brain structures.

Beneath the dura is the arachnoid mater, a much thinner, web-like layer, followed by the pia mater, which is a delicate membrane that closely follows every contour of the brain. The space between the dura and arachnoid is a potential gap called the subdural space, not a true protective layer. Because of its toughness and location, the dura mater is the outermost, most protective layer.