and the last layer?
It is the outermost of the three layers of membrane called the meninges that protect the central nervous system.
Dura mater
 It is the outermost of the three layers of membrane called the meninges that protect the central nervous system. 
which layer of meninges is affected in meningitis The three membranes - pia mater, arachnoid mater and dura mater can you tell me something about the first one mentioned above? It is the delicate innermost layer of the meninges, the membranes surrounding the brain and spinal cord. can you tell me something about the second layer mentioned? It is a derivative of the neural crest mesectoderm in the embryo.
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Dura mater [SEP] Introduction
Dura mater is a thick membrane made of dense irregular connective tissue that surrounds the brain and spinal cord. It is the outermost of the three layers of membrane called the meninges that protect the central nervous system. The other two meningeal layers are the arachnoid mater and the pia mater. The dura surrounds the brain and the spinal cord. It envelops the arachnoid mater, which is responsible for keeping in the cerebrospinal fluid. It is derived primarily from the neural crest cell population, with postnatal contributions of the paraxial mesoderm.