Final answer:
The pia mater is the meningeal layer that follows the surface contours of the brain and spinal cord. It is a thin fibrous membrane which penetrates into the grooves and indentations of the central nervous system, providing a protective layer.
Step-by-step explanation:
The meningeal layer that follows the surface contours of the brain and spinal cord is the pia mater. The meninges, a series of protective tissue layers, envelop the central nervous system (CNS), including the brain and spinal cord. Among these layers, the dura mater, the arachnoid mater, and the pia mater are major constituents.
Dura mater, the outer layer, is a thick and robust sheath covering the entire CNS. The middle layer, known as arachnoid mater, forms a loose sac and is characterized by web-like threads termed arachnoid trabeculae, thus deriving its name. The layer immediate to the CNS surface is pia mater, a fine membrane that closely follows the convolutions of the cerebral cortex, fitting into grooves and indentations.
The term 'pia mater' originates from Latin, meaning 'tender mother.' The pia mater penetrates into the intricate depressions of the CNS, covering the cerebral and cerebellar cortex's inner surfaces, indicating its integral function in covering and protecting the brain's surface contours and spinal cord.
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