The myelin sheath is a protective covering that surrounds the axons of many neurons in the nervous system. It is made up of fatty substances and helps to insulate the axon, allowing electrical signals to transmit more quickly and efficiently. This insulation is crucial for proper communication between nerve cells. Myelin is produced by two types of cells: oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system. Damage to the myelin sheath can lead to neurological disorders, such as multiple sclerosis, where the communication between the brain and body is disrupted.