Scapulohumeral Rhythm

Scapulohumeral rhythm describes coordination between shoulder joint motion and scapular movement. During shoulder abduction, the scapula must move rather than remain fixed. The scapula must upwardly rotate and position itself to allow the humerus to continue moving without compensations. The article uses an approximate two-to-one humeral-to-scapular motion ratio as a practical model, not an exact rule for every person or range. An apparent shoulder problem may originate from scapular movement or the thoracic surface under the scapula.