Myofascial pain patterns of the scalene muscles (1)

Essential (solid red) and spillover (stippled red) referred pain projects to the pectoral, medial scapular border, and lateral arm, often extending down the radial aspect of the forearm to the thumb and index finger. Entrapment of the lower trunk of the brachial plexus causes ulnar distribution pain and paresthesias, and the unexpected dropping of objects from the hand, whereas subclavian vein compression causes edema of the fingers and dorsum of the hand. (From Travell JG, Simon DG. Myofascial pain and dysfunction, scalene muscles, the trigger point manual. Volume 1. Baltimore: Williams & Wilkins, 1983:345, with permission.)