What is pial?

Pia mater, or pia, is one of the three layers that make up the meninges, which is the protective covering of the brain and spinal cord. Pia is the innermost layer, lying directly on the surface of the brain and spinal cord. It is a thin, delicate layer made up of a layer of connective tissue, blood vessels, and small amounts of nervous tissue. Its main function is to provide a barrier between the brain and the skull, protecting the brain from external injury, and supplying the brain with nutrients and oxygen through the blood vessels. Pial cells are also important for regulating cerebrospinal fluid (CSF), which surrounds the brain and spine. Disorders affecting the pial layer include subdural hematoma, intracranial hemorrhage, meningitis, and encephalitis.