Which structure is NOT a part of the meninges?

The medulla is not part of the meninges because it refers to a specific region of the brainstem involved in various autonomic functions, such as regulating heart rate and breathing. The meninges, on the other hand, are a set of three protective membranes that envelop the brain and spinal cord, providing structural support and serving as a barrier against infection.

The three layers that make up the meninges are the dura mater, arachnoid mater, and pia mater. The dura mater is the tough outer layer that provides the most protection. The middle layer, the arachnoid mater, has a web-like structure and is situated between the dura mater and pia mater, which is the innermost layer that closely adheres to the surface of the brain and spinal cord. Each of these layers plays a critical role in housing cerebrospinal fluid and providing a protective cushion for the central nervous system.