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How do the meninges and cerebrospinal fluid protect the central nervous system?

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Diagram comparing action potential conduction in myelinated and unmyelinated axons, showing a neuron with labeled cell body, myelin sheath, nodes of Ranvier, and the flow of electrical signals along each type of axon. — nervous system In a myelinated axon, the myelin sheath prevents the local current (small black arrows) from flowing across the membrane. This forces the current to travel down the nerve fibre to the unmyelinated nodes of Ranvier, which have a high concentration of ion channels. Upon stimulation, these ion channels propagate the action potential (large green arrows) to the next node. Thus, the action potential jumps along the fibre as it is regenerated at each node, a process called saltatory conduction. In an unmyelinated axon, the action potential is propagated along the entire membrane, fading as it diffuses back through the membrane to the original depolarized region.

The meninges and cerebrospinal fluid (CSF) work together to provide essential protection for the central nervous system.

The Role of the Meninges

The meninges consist of three protective membranes that envelop the brain and spinal cord:
* Dura mater: The outermost, strong, and dense layer that supports the brain, partitions it into sections, and acts as a periosteum for the skull.1
* Arachnoid: A thin, transparent membrane that forms a loosely fitting sac around the brain.1
* Pia mater: The innermost membrane that adheres firmly to the surface of the brain and spinal cord.1

The Role of Cerebrospinal Fluid

CSF fills the ventricles of the brain and the subarachnoid space between the pia mater and the arachnoid. Its protective functions include:12
* Mechanical Cushioning: It acts as a shock absorber, dulling the force of impacts to the head by distributing the energy.3
* Support and Lubrication: It supports the brain and provides lubrication between the brain, spinal cord, and surrounding bones.3
* Pressure Regulation: It maintains constant intracranial pressure by adjusting its volume in response to changes in blood or brain tissue volume.3
* Waste Removal: It transports metabolic waste, antibodies, and other chemicals away from neural tissue into the bloodstream.3