Scapulohumeral Rhythm

Scapulohumeral Rhythm is the ratio of movement between the scapula and the humerus. This movement is important in order to achieve full ROM. For every 3° of shoulder movement there is 1° of movement at the scapulothoracic joint and 2° of movement at the glenohumeral joint. As the scapula upwardly rotates, the glenoid fossa is also rotating to maintain connection with the head of the humerus. This movement must be synchronous to allow full ROM. This rhythm is clinical relevant, because it is needed for efficient arm movement and shoulder abduction. It is important that these joints work with each other to allow good length-tension relationship for shoulder abduction. For full ROM, the humeral head must rotate laterally. Full ROM of the shoulder is 180° with 60° from the scapulothoracic joint and 120° from the glenohumeral joint. If there is not adequate upward scapular rotation an impingement can occur in the subacromial space which causes pain and prevents full ROM. Full ROM of the shoulder is needed in order to complete ADLs such as getting dressed and brushing your hair.