Which muscle/tendon dysfunction causes Superior Escape?

Superior Escape, also known as superior shoulder migration, typically occurs due to dysfunction of the rotator cuff muscles that play a critical role in the stabilization and movement of the humeral head within the glenoid cavity. The supraspinatus, being one of the important rotator cuff muscles, is particularly significant in this context because it helps maintain the position of the humeral head during arm elevation and shoulder activities.

When there is compromise or dysfunction of the supraspinatus tendon, it can lead to an inability to properly stabilize the humeral head. This instability allows the head of the humerus to migrate superiorly, hence the term "superior escape." The supraspinatus is instrumental in activating and initiating abduction and also provides important support during overhead motions.

In contrast, the other rotator cuff muscles, such as subscapularis, infraspinatus, and teres minor, serve different roles and while they contribute to overall shoulder stability and movement, they are not as directly involved in preventing superior migration as the supraspinatus. Dysfunction in these muscles leads to other types of shoulder problems, but for the specific phenomenon of superior escape, the supraspinatus is the most critical.