Which meninges layer is the outermost, tough, vascularized and richly innervated?

• A. Pia mater
• B. Arachnoid mater
• C. Dura mater
• D. Parietal pleura

Answer: (C)

The outermost protective meningeal layer is the dura mater, a tough, dense fibrous membrane that is both well vascularized and richly innervated. This sturdiness helps safeguard the brain and spinal cord, while the abundant nerves explain why irritation of this layer can produce strong head and neck pain. The dura has two components: a periosteal layer that lines the inner skull and a meningeal layer that continues around the brain and down the spinal cord; they are usually fused except where they form dural venous sinuses to drain blood. By contrast, the arachnoid mater is the middle, web-like layer, and the pia mater is the delicate inner layer that closely adheres to the brain surface. The parietal pleura is a lining of the thoracic cavity and has no role in the meninges.