Scapulohumeral Rhythm

The scapulohumeral rhythm is relevant because it allows for full ROM for arm movements. It provides for good muscle length tension of shoulder muscles to allow for a strong amount of force during movements. It is also important because it improves the congruency and synchronicity of the scapula and humerus. This congruency is important for therapists to note in order to ensure that the correct alignment is kept and that injury is not caused to the GH joint during manipulation. It tells us that for every 1° of movement at the scapulothoracic joint there will be 2° of movement at the glenohumeral joint which will in total add up to 3° of movement at the shoulder. This ratio is important for when we are testing ROM because then we can know the degrees of movement at the ST joint and the degrees of movement at the GH joint. Additionally, if there is an injury and the ROM is not within normal limits then this could cause problems to the subacromial space and injure the contents which include the supraspinatus tendon, subacromial bursa, long head of biceps, and joint capsule.