PIA
n. uncountablen. Stands for pia mater. The thin, delicate layer that covers the brain and spinal cord. It is the innermost of the three layers that protect your central nervous system.
n. Abbreviation for pia mater. The delicate, vascularized innermost layer of the meninges that directly envelopes the brain and spinal cord. It follows the contours of the brain's surface, dipping into the sulci and fissures.
The pia is the layer closest to the brain.
During the surgery, the doctor carefully avoided damaging the pia to protect the underlying neural tissue.
The meninges consist of three distinct membranes—the dura mater, the arachnoid mater, and the pia mater—which collectively serve to protect the central nervous system from mechanical injury.
Often referred to by its full Latin name, 'pia mater'.