Which term describes the muscle that contracts to produce movement?

Which term describes the muscle that contracts to produce movement?

• A. agonist
• B. antagonist
• C. stabilizer
• D. fixator

Answer: (A)

When a movement happens, the muscle that contracts to produce the action is the agonist. It actively shortens to pull on the bone and drive the joint through the range of movement. The opposing muscle, which relaxes to let that movement occur, is the antagonist. Other muscles can help by stabilizing the joint so the movement is precise and controlled; these are stabilizers. Some muscles act to hold a body part steady, fixing it in place so the main movement can occur efficiently; these are fixators. For example, during elbow bending to lift something, the biceps brachii acts as the agonist, contracting to flex the elbow, while the triceps brachii serves as the antagonist, relaxing to allow the bend. At the same time, stabilizers around the shoulder and trunk help keep the body steady for smooth, controlled movement.

When a movement happens, the muscle that contracts to produce the action is the agonist. It actively shortens to pull on the bone and drive the joint through the range of movement. The opposing muscle, which relaxes to let that movement occur, is the antagonist. Other muscles can help by stabilizing the joint so the movement is precise and controlled; these are stabilizers. Some muscles act to hold a body part steady, fixing it in place so the main movement can occur efficiently; these are fixators. For example, during elbow bending to lift something, the biceps brachii acts as the agonist, contracting to flex the elbow, while the triceps brachii serves as the antagonist, relaxing to allow the bend. At the same time, stabilizers around the shoulder and trunk help keep the body steady for smooth, controlled movement.