What is Normal Muscle Control?

Overview of Muscles
To better understand what happens in muscles that are affected by spasticity, it is helpful to first understand some key facts about muscles and the nerves that control their movements.

More than 600 muscles, along with the bones, make up the musculoskeletal system.

• The bones provide the structure or support for the body, and the muscles provide the ability to move.
• Muscles are connected to bones by tough cords of tissue called tendons.
• Most muscles reach from one bone to another and usually cross a joint.
• The muscles cause the bones to move in relationship to each other.

Most muscles of the musculoskeletal system work in pairs – called agonists and antagonists. During a movement, the muscle responsible for moving the body part contracts or shortens; this muscle is called the agonist. The antagonist muscle acts against or in opposition to the agonist muscle, stretching when the agonist contracts. The antagonist muscle is responsible for moving the body part back to its original position.

A muscle acts as the agonist in one action and as an antagonist in the opposite action. For example, when bending the elbow and raising the hand toward the shoulder, the bicep muscle contracts and is the agonist; the tricep muscle stretches and is the antagonist. When the movement is reversed and the elbow is extended, the tricep muscle contracts (is the agonist) and the bicep muscle lengthens (is the antagonist).

Click here to learn more