n. 1. the thin layer of mesoderm that surrounds the brain of the embryo. It gives rise to most of the skull and the membranes that surround the brain. See also chondrocranium. 2. see meninges.
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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