What is the main function of the myelin sheath?

The main function of the myelin sheath is to facilitate impulse conduction. Myelin is a fatty substance that surrounds and insulates nerve fibers, allowing electrical impulses to transmit more rapidly along the axon. This is achieved through a process known as saltatory conduction, where the action potentials jump from one Node of Ranvier (gaps in the myelin sheath) to the next. This increase in conduction speed is vital for efficient communication between neurons, particularly in the case of motor and sensory functions in the nervous system. The presence of the myelin sheath significantly improves the overall speed and efficiency of nerve signaling, which is crucial for normal physiological function.