What is the main role of the coracobrachialis in shoulder movement?

The coracobrachialis primarily functions to assist in shoulder adduction, which is the movement of bringing the arm closer to the body along the frontal plane. Originating from the coracoid process of the scapula, it inserts onto the humerus. When the coracobrachialis contracts, it pulls the arm toward the midline, which is essential for actions such as reaching across the body.

Additionally, while the coracobrachialis may have a secondary role in flexing the shoulder due to its positioning, its primary contribution lies in adduction. This is particularly important during athletic movements, weightlifting, or various other physical activities where controlled movement of the arm toward the body is required. Understanding this function helps clarify the unique contributions of the muscles involved in shoulder mobility and stability.