How does the scapulohumeral rhythm change from 90-180 degrees of humeral elevation?

• A. The scapula moves more than the humerus
• B. 1 degree of scapular upward rotation for every 1 degree of humeral elevation
• C. No scapular motion occurs
• D. Scapular rotation decreases

Answer: (B)

In the context of scapulohumeral rhythm during humeral elevation, the correct understanding of the relationship between scapular movement and humeral movement is crucial. When the arm is elevated from 90 to 180 degrees, there is a specific pattern of movement between the scapula and the humerus that maintains optimal shoulder function and stability.

During this phase of elevation, the ratio of scapular upward rotation to humeral elevation changes to a favorable alignment for further range and efficiency. For every degree of humeral elevation above 90 degrees, there is approximately 1 degree of scapular upward rotation. This coordinated motion allows for greater shoulder elevation while keeping the shoulder joint stable and decreasing the risk of impingement.

Understanding this rhythm is essential for athletic training, rehabilitation, and performance, as it emphasizes the importance of both scapular and humeral movements working together harmoniously as arm elevation progresses. The ratios of movement help prevent unnecessary strain on the shoulder and promote functional athletic performance.