What is a myelin sheath do?

Myelin sheath: Myelin is a electrically insulating material that forms a layer, the myelin sheath, usually around only in the part of the cella called the axon it is essential for the proper functioning of the nervous system. The main purpose of a myelin layer (or sheath) is to increase the speed at which impulses propagate between brain cells. Mulitple sclerosis is a disease that affects the myelin sheath.

Aids in conduction: Myelin sheath is a substance covering the peripheral nerves acting almost like the plastic you see covering a basic electrical wire. It offers not only protection to some degree but allows for a more rapid conduction of an impulse along the length of a nerve. The myelin also had tiny divits or nodes along its length that allow for the impulse to " jump" from node allowing for faster conduction.