The principle of levers is well established in physics and the body uses them everywhere. From arms to legs and neck.
A lever is a rigid object that is used with an appropriate fulcrum or pivot point to multiply the mechanical force that can be applied.
Most of the muscles in the human body use bones as the levers against which they work for example, the Biceps and Brachialis muscles in the arm use the forearm bones in order to apply force and move our lower arms.
The body employs 1st class levers as one of the ways of assisting movement.
Finding 2nd class levers in the human body is tricky but we do use them.
The human body uses 3rd class levers to move the long bones in your body.
Without these vital anchor points, movement would be impossible.