During scapular upward rotation, what is the ratio of humeral movement to scapular movement?

During scapular upward rotation, what is the ratio of humeral movement to scapular movement?

• A. 3:2
• B. 2:1
• C. 1:1
• D. 4:1

Answer: (B)

The movement you see is driven by scapulohumeral rhythm, a coordinated pattern between the shoulder joint and the shoulder blade. In a typical overhead lift, the arm’s movement at the glenohumeral joint is about twice as large as the upward rotation of the scapula. Concretely, about 120 degrees of humeral motion combine with roughly 60 degrees of scapular upward rotation to achieve about 180 degrees of total arm elevation. So the ratio of humeral movement to scapular movement is two to one. (Note: early in elevation, most of the initial range comes from the humerus, with the scapula contributing more as you reach higher.)

The movement you see is driven by scapulohumeral rhythm, a coordinated pattern between the shoulder joint and the shoulder blade. In a typical overhead lift, the arm’s movement at the glenohumeral joint is about twice as large as the upward rotation of the scapula. Concretely, about 120 degrees of humeral motion combine with roughly 60 degrees of scapular upward rotation to achieve about 180 degrees of total arm elevation. So the ratio of humeral movement to scapular movement is two to one. (Note: early in elevation, most of the initial range comes from the humerus, with the scapula contributing more as you reach higher.)