What are Prime movers, Means when we exercise which muscle move first and which muscle help them to do his job done. Interesting! When we exercise in the gym there is variety of roles that our body muscle play during a movement. Variety of roles that our body muscle plays during a movement. So we discuss about those movements and muscle involve in it today:

Prime movers/agonist or Main movers:This is our large muscle when we train in gym for example doing biceps curl our biceps brachii means in general biceps Main Muscle is prime mover.
Antagonist:You know these opposite muscle oppose the action of prime movers means they are opposite side of main muscle they are relax and stretch, for example while doing biceps curl triceps are antagonist means opposite muscle.
Synergist means assisted muscle:These muscles help the prime movers in movement, they are small In size as well for example while doing biceps curl assisted smaller muscle are brachialis and brachioradialis these both are part of biceps muscle.4. Fixators: Means stabilizers these muscles help to hold the body whiles other part of body is moving for example doing biceps curl deltoids and abdominal are fixators.
I hope this will gain your knowledge.

Thanks