The function of the myelin sheath is to "protect and increase the speed of action potential down the axon".
Explanation:
The 'myelin sheath' is the insulating layer around our nerve cells. It is produced by a method called myelination. Some special cells called 'Schwann cells' are responsible for creating and storing large amounts of myelin. They get covered around the axon of the nerve cells. They appear white, that's why are called white matter. It is composed of lipids and proteins and has water absorption capacity. Its main function, however, is not just to provide protection to the nerves from other electrical impulses but also to speed up the time taken by a nerve to transverse an axon.
