Synergists - muscles working together

Mandible - temporomandibular joint

Elevation

          Masseter
          Temporalis
          Medial pterygoid

Depression

          Geniohyoid
          Mylohyoid
          Stylohyoid
          Digastic (with hyoid bone fixed)
          Platysma (assists)

Protraction

          Lateral pterygoid (bilaterally)
          Media pterygoid (bilaterally)

Retraction

          Temporalis
          Digastric