Synergists - muscles working together

Ribs / Thorax

Elevation/Expansion

          Anterior scalene (bilaterally)
          Middle scalene (bilaterally)
          Posterior scalene (bilaterally)
          Sternocleidomastiod (assists)
          External inercostals (assists)
          Serratus posterior superior
          Pectoralis major (may assist if arm is fixed)
          Pectoralis minor (if scapula is fixed)
          Seratus anterior 9if scapula is fixed)
          Subclavius (first rib)

Depression/Collapse

          Inernal intercostals (assists)
          Serratus posterior inferior