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Definition

Meninges (singular is meninx) is the collective term for the three membranes covering the brain and spinal cord. The meninges are composed of the dura mater (outer), the arachnoid (middle), and the pia mater (inner). In common usage, the membranes are often referred to as simply the dura, pia, and arachnoid.

Description

Dura is the Latin word for hard, while pia in Latin means soft. The dura mater was so-named because of its tough, fibrous consistency. The pia mater is thinner and more delicate than the dura mater, and is in direct contact with the neural tissue of the brain and spinal cord. Along with the arachnoid layer and the cerebrospinal fluid (CSF), the dura and pia membranes help cushion, protect, and nourish the brain and spinal cord.

Mater is Latin for mother, and thus refers to the membranes' protective and nourishing functions. Each of the meninges can also be classified as to the...