In this case it's the tricep. In this case it's the bicep. Now we have many other muscles involved in this motion and these muscles, these other muscles that help the bicep and the triceps are known as our synergist muscles. So we also have synergist muscles that are involved in aiding in aiding the agonist antagonist muscles. Now we can also refer to these muscles in a different way. We also have flexor muscles and extensor muscles.