Which layer of the central nervous system is involved in Meningitis?

Meningitis is an inflammatory condition that primarily affects the protective membranes, known as the meninges, surrounding the brain and spinal cord. The meninges consist of three layers: the dura mater, arachnoid mater, and pia mater. In cases of meningitis, the inflammation typically involves both the pia mater and the arachnoid mater, collectively referred to as the leptomeninges.

The pia mater is the innermost layer, closely adhering to the surface of the brain and spinal cord, while the arachnoid mater is the middle layer, situated between the pia mater and the outer dura mater. When pathogens such as bacteria or viruses invade the cerebrospinal fluid (CSF) or the subarachnoid space, they can lead to inflammation in these two layers. This is why the correct answer highlights the involvement of both the pia mater and the arachnoid in the context of meningitis, as their inflammation is central to the pathophysiology of the disease.

The dura mater, being the outermost layer, typically does not become inflamed in cases of meningitis, which is a crucial point that supports the choice highlighting the other two layers.