Which muscle helps in external rotation of the shoulder?

The muscle responsible for external rotation of the shoulder is the infraspinatus. This muscle is one of the four rotator cuff muscles and is located on the posterior aspect of the scapula. It originates from the infraspinous fossa and inserts on the greater tubercle of the humerus. When it contracts, it pulls the humerus in a way that rotates it outward, or externally. This action is essential for various overhead movements and stabilizing the shoulder joint during activities that involve arm elevation or rotation. The infraspinatus plays a crucial role in maintaining shoulder integrity and preventing injuries, making it a key muscle for athletes and anyone engaging in activities that require shoulder mobility and strength.

The other muscles listed do not primarily facilitate external rotation: the subscapularis is involved in internal rotation, teres major assists in internal rotation and adduction, and coracobrachialis contributes to arm flexion and adduction rather than rotation.