Synergists - muscles working together

Elbow - humeroulnar and humeroradial joints

Flexion

          Biceps brachii
          Brachialis
          Brachioradialis
          Flexor carpi radialis
          Flexor carpi ulnaris
          Palmaris longus
          Pronator teres 
          Extensor carpi radialis longus
          Extensor cari radialis brevis

Extension 

          Triceps brachii
          Anconeus