Synergist Muscle

A synergist muscle assists the agonist muscle or “primary mover” for a specific action at a joint.

This muscle is not the main muscle involved in the action, but works in synergy with the primary muscle. These muscles help make movements more accurate and fluid.

For example, the brachioradialis muscle on the forearm assists the biceps brachii muscles when lifting a cup to take a sip!

A child uses two hands to bring a cup of milk to their mouth. Labels identify the biceps muscles (agonist) and brachioradialis muscle (synergist).