How does functional scapular instability affect the rotator cuff?

Functional scapular instability significantly affects the rotator cuff by leading to insufficient strength and control in the scapulothoracic muscles. When scapular instability is present, the muscles responsible for stabilizing the scapula, such as the trapezius, serratus anterior, and rhomboids, may become weak or dysfunctional. This weakness can hinder the ability of the scapula to maintain a stable and optimal position during shoulder movements.

A stable scapula is crucial for the rotator cuff to function effectively, as the rotator cuff muscles rely on the position of the scapula to generate proper force and movement around the glenohumeral joint. Weakness in the scapulothoracic muscles can disrupt the coordination and timing between the scapula and the rotator cuff, potentially leading to rotator cuff injuries or dysfunction. Consequently, the reduction in scapular stability directly affects the rotator cuff’s ability to maintain shoulder stability and perform effectively during upper extremity activities.