What is the protective membrane system that covers the brain and spinal cord?

The protective membrane system that covers the brain and spinal cord is known as the meninges. This system consists of three distinct layers: the dura mater, the arachnoid mater, and the pia mater. Together, these layers provide structural support and protection for the central nervous system.

The dura mater is the outermost layer, known for its toughness and ability to protect the underlying structures. The arachnoid mater is the middle layer, which has a web-like structure and serves as a barrier against infection. The pia mater is the innermost layer, directly adhering to the surface of the brain and spinal cord, providing additional protection and containing the blood vessels that supply them.

While options like the pia mater refer specifically to one of the layers of the meninges, and cerebrospinal fluid plays a critical role in cushioning the brain and spinal cord, neither of these options represents the entire membrane system. The cerebral cortex, on the other hand, refers to the outer layer of the brain involved in many high-level functions, not a protective membrane. Thus, the meninges are the comprehensive system that embodies the protective layers surrounding these vital structures.