What muscle group is involved in the stability of the shoulder aside from the rotator cuff?

The deltoids play a significant role in shoulder stability, in addition to the rotator cuff muscles. They encase the shoulder joint and help to stabilize it during movements. The deltoid muscle is responsible for the abduction, flexion, and extension of the arm, contributing to the overall functional stability of the shoulder.

This muscle works synergistically with the rotator cuff to maintain the position of the head of the humerus in the glenoid cavity, thereby preventing dislocations and allowing for a wide range of shoulder motions. The deltoids are essential for dynamic stabilization, particularly during activities that involve lifting or throwing.

In contrast, the other options, such as the pectorals, trapezius, and biceps, certainly play roles in shoulder movement and support but do not contribute as directly to the stabilization of the shoulder joint as the deltoids do. The pectorals primarily aid in flexing and adducting the arm, the trapezius is vital for various movements of the scapula, and the biceps are more known for their role in elbow flexion rather than shoulder stability.