Which rotator cuff muscle is most frequently injured?

The supraspinatus muscle is the most frequently injured rotator cuff muscle due to its anatomical position and role in shoulder movement. It is primarily responsible for the abduction of the arm, especially in the initial stages of lifting the arm away from the body. This muscle is located at the top of the shoulder and is prone to injury from repetitive overhead activities, which can lead to tendonitis or tears.

In addition, the supraspinatus tendon passes under the acromion, making it susceptible to impingement when the arm is raised or during certain movements. This impingement can occur especially in individuals who engage in sports or occupations that require repetitive overhead motions. The high incidence of injuries involving this muscle highlights its importance in shoulder stability and function.

In contrast, while the other muscles of the rotator cuff also play crucial roles in shoulder mechanics, they are less frequently involved in injuries compared to the supraspinatus. The infraspinatus and teres minor primarily aid in external rotation, and the subscapularis is responsible for internal rotation. Though these muscles can be injured, their locations and roles in movement mean they typically do not suffer from the same frequency of injuries as the supraspinatus.