What is the function of the myelin sheath in the nervous system?

The function of the myelin sheath in the nervous system is primarily to insulate axons and enhance the speed of electrical impulse transmission. Myelin is a fatty substance that wraps around the axons of neurons, forming a protective layer. This insulation prevents the electrical signals from dissipating into the surrounding area, allowing the signals to travel more efficiently along the nerve fiber.

The myelin sheath facilitates a process called saltatory conduction, wherein action potentials jump from one node of Ranvier (gaps in the myelin sheath) to the next. This jump increases the speed of transmission compared to unmyelinated axons, where the electrical impulses must travel along the entire length of the axon continuously. This rapid transmission is crucial for the efficient functioning of the nervous system, allowing for quick responses and communication between neurons.

The other options do not accurately describe the role of the myelin sheath. It does not provide physical protection to the brain from injury, nor does it have a direct role in nourishing neurons or storing neurotransmitters. Instead, its primary function revolves around ensuring effective and rapid communication within the nervous system.