Definition of pia mater in US English:

pia mater


  • The delicate innermost membrane enveloping the brain and spinal cord.

    See also meninges, pia
    • ‘The lining consists of three layers - dura, arachnoid and pia.’
    • ‘The innermost layer is the pia mater, a delicate vascular layer adherent to the surface of the brain and spinal cord.’
    • ‘These veins are found in the maternal part of the placenta, the spinal cord pia mater, retina, sinuses of the dura mater, most cerebral veins, trabecular veins of the spleen, and veins of the nail bed.’
    • ‘Arachnoid and pia are also called leptomeninges (thin membranes).’
    • ‘The pia mater has received little attention regarding its function in the deformation of the spinal cord under compression.’


Late 19th century: from medieval Latin, in full literally ‘tender mother’, translating Arabic al-'umm ar-raḳīḳa.