What is the main function of the myelin sheath?

The myelin sheath plays a critical role in the nervous system by insulating axons, which are the long projections of neurons that carry electrical impulses away from the cell body. This insulation is essential as it results in a significant increase in the speed at which nerve impulses, or action potentials, propagate along the axon.

In myelinated axons, the electrical signal jumps between gaps in the myelin sheath called nodes of Ranvier, a process known as saltatory conduction. This allows for much faster transmission of signals compared to unmyelinated axons, where the impulse must travel along the entire length of the membrane. Thus, the primary function of the myelin sheath is to facilitate rapid communication between neurons, enabling efficient functioning of the nervous system.

While support for neuron growth, neurotransmitter release, and synaptic connections are important for overall neural function and communication, they do not directly pertain to the specific and primary role of myelin, which is focused entirely on the insulation and speed of impulse transmission.