The muscles used to move bones and the muscles in the face are voluntary muscles. Voluntary muscles are the muscles a person chooses to move, unlike involuntary muscles, which are the muscles that are not consciously controlled.
Each voluntary muscle helps a person move around. Most are connected to the bones by tendons, and the muscle runs along the length of the entire bone and is attached to another bone on the other side of the joint. The muscle moves the bone at the insertion. Voluntary muscles cannot extend on their own, so muscles must work in opposing pairs. The extensor is the contracting muscle, and the flexor is the expanding muscle.