The scalene muscles are located in the neck and originate on c3-c6 and insert on the first and second rib. These muscles act to laterally flex the neck, and assist in respiration by helping to elevate the ribs. Trigger points can form in this muscle from acute injuries such as whiplash, or from chronic injury such as poor posture or shallow nervous breathing. Trigger points in these muscles can refer pain in two finger like projections into the chest. Other common patterns are into the shoulder, scapula and down the lateral arm, and into the thumb and index finger. The scalene muscle can impinge on the brachial plexus, causing nerve pain or numbness down the arm. This is called thoracic outlet syndrome.