Myelin sheath – insulation for axons

This is best thought of as insulation for axons. It’s a fatty white sheath around the axons which provides electrical insulation and protection, and actually helps increase the speed of impulses.

The myelin sheath insulates impulses in axons and helps to speed them up

My violin (myelin) had to be played in a well-insulated room.

Image showing the myelin sheath containing the axon

The myelin sheath is wrapped around the axon in a spiral fashion. It’s like a rubber coating on a copper wire, protecting the axon as well as speeding up impulses.

Graphic showing that not all axons are protected and only time critical axons are protected

Cross-sectional view of myelin surrounding axons, as seen under an electron microscope.

NOTE:

Not all axons are myelin-coated (or myelinated). Some shorter axons, and some that send messages that are not particularly time-critical, do not have myelin sheaths.