What is the fibrous covering on the surface of bone that is involved in thickening of the bone called?

The fibrous covering on the surface of bone that is involved in thickening of the bone is called periosteum.

This covering layers over every bone in our body, except for surfaces of the joints, which need to be more flexible and movable than the rest of the bones. It is a very thin membrane and protects your bones and your entire body from any type of injury as much as it can.