Final answer:
The pia mater is a thin, vascularized fibrous membrane that tightly adheres to the brain and spinal cord, forming part of the meninges. It supports blood vessels that nourish the CNS and contributes to the blood-brain barrier.
Step-by-step explanation:
The pia mater is a delicate and highly vascular layer that closely adheres to the surface of the brain and spinal cord as part of the meninges, the protective coverings of the central nervous system (CNS). It is made of a thin fibrous membrane and is thought to form a fluid-impermeable layer around the CNS. Complemented by the other meningeal layers such as the dura mater and arachnoid mater, the pia mater plays a critical role in protecting the brain, providing a supportive framework for adjacent blood vessels, and containing cerebrospinal fluid (CSF) that helps cushion the brain and maintain a stable environment.
Functions of the Pia Mater
The pia mater extends into every convolution of the CNS, lining the sulci in the cerebral and cerebellar cortices. It fits into various grooves and indentations, highlighting its intimate relationship with the CNS tissue. The pia mater supports and contains the blood vessels that nourish the central nervous tissue. The CSF-filled subarachnoid space lies between the pia mater and the arachnoid layer.
In addition to its protective role, the pia mater also contributes to the formation of the blood-brain barrier, which restricts the transfer of materials from the blood to the brain, ensuring a stable environment for neural functioning.