Scapulohumeral Rhythm
The scapula and humerus work together for you to be able to move your arms in full available range of motion (ROM) in different planes (1). The scapula rotates upward, downward, and side to side (protraction, retraction) along the back portion of the thoracic cavity. This area where movement occurs is called the scapulothoracic joint, however, it is not a true joint. The scapula is joined with the humerus at the glenohumeral joint. The scapulothoracic and glenohumeral joint movements work in junction with each other to allow ROM to reach above the head and promote a good length-tension relationship (2). This ratio of movement is called the scapulohumeral rhythm.
The scapulohumeral rhythm is clinically relevant to understand why a person may be limited in ROM in flexion, abduction, and the rotation of the humerus. The humerus moves 180 degrees at full ROM, the glenohumeral joint moves 120 degrees, and the scapulothoracic joint moves 60 degrees. The joints maintain this ratio when there is a limitation at either one. This means that if there is not adequate ROM at the scapulothoracic or glenohumeral joint, this will affect the ROM of the humerus as well (3).
Consider some occupations that you engage in daily, such as brushing your hair, reaching in the cabinet, removing a hanger from the rack, and closing the curtains. These activities require adequate ROM to complete. Limitations in the scapulohumeral rhythm can inhibit a person’s occupational performance and ability to complete these activities. An adequate ROM is also important in scapulohumeral rhythm to prevent injury (4) and reduce shearing forces (5). If there is a limitation in ROM, this can cause shoulder impingement of the subacromial space where the tendon of the long head of the bicep, bursa, and supraspinatus reside. This can cause shoulder pain and result in guarding the joint (Refusing to move the arm through different ROM).
The scapulohumeral rhythm is clinically relevant to understand why a person may be limited in ROM in flexion, abduction, and the rotation of the humerus. The humerus moves 180 degrees at full ROM, the glenohumeral joint moves 120 degrees, and the scapulothoracic joint moves 60 degrees. The joints maintain this ratio when there is a limitation at either one. This means that if there is not adequate ROM at the scapulothoracic or glenohumeral joint, this will affect the ROM of the humerus as well (3).
Consider some occupations that you engage in daily, such as brushing your hair, reaching in the cabinet, removing a hanger from the rack, and closing the curtains. These activities require adequate ROM to complete. Limitations in the scapulohumeral rhythm can inhibit a person’s occupational performance and ability to complete these activities. An adequate ROM is also important in scapulohumeral rhythm to prevent injury (4) and reduce shearing forces (5). If there is a limitation in ROM, this can cause shoulder impingement of the subacromial space where the tendon of the long head of the bicep, bursa, and supraspinatus reside. This can cause shoulder pain and result in guarding the joint (Refusing to move the arm through different ROM).
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