pl. n. (sing. meninx) the three connective tissue membranes that line the skull and vertebral canal and enclose the brain and spinal cord (see illustration). The outermost layer – the *dura mater (pachymeninx) – is inelastic, tough, and thicker than the middle layer (the *arachnoid mater) and the innermost layer (the *pia mater). The inner two membranes are together called the leptomeninges; between them circulates the *cerebrospinal fluid.... meninges
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