Synergists - muscles working together

Thumb - First carpometacarpal and metacarpophalangeal joints

Flexion

          Flexor pollicis longus
          Flexor pollicis brevis
          Adductor pollicis
          Palmar interosseri 1st

Opposition

          Opponens pollicis
          Flexor pollicis brevis
          Abductor pollicis brevis

Extension

          Extensor pollicis longus
          Extensor pollicis brevis
          Abductor policis longus
          Palmar interossei 1st