What is the ratio of scapular upward rotation to humeral elevation from 30-90 degrees?

The correct response highlights an important principle in biomechanics regarding the relationship between the scapula and humerus during shoulder elevation. Specifically, for every 2 degrees of humeral elevation in the range from 30 to 90 degrees, there is 1 degree of upward scapular rotation.

This ratio is significant because it reflects how the scapula moves in coordination with the humerus to allow for a full range of motion at the shoulder joint. During this phase of arm elevation, upward rotation of the scapula is essential for maintaining the stability of the shoulder and ensuring that the glenoid cavity is oriented properly to accommodate the moving humeral head.

Understanding this relationship is crucial for rehabilitation and training, as it emphasizes the need for proper scapular mechanics alongside humeral movement to prevent injuries and improve function. The dynamics of this ratio also underscore the complexity of shoulder movements and the integrated role of the shoulder girdle in facilitating upper limb mobility.