OT430: scapulohumeral rhythm

Scapulohumeral rhythm is defined as ratio of movement between the scapula and humerus. This ratio is for every three degrees of movement the scapulothoracic joint accounts for one degree and the glenohumeral joint accounts for two degrees. It is important that this ratio be maintained for full 180 degrees of motion. It is important to consider this ratio when a client does not have full ROM in order to find out which joint may be responsible for the lack of movement. Improper function in either joint could result in a decrease in ROM, an impingement, or pain. A lack of full scapulohumeral rhythm can point to signs of defects or problems with muscles that move the scapula such as trapezius and serratus anterior or issues with the humeral head rotating laterally.