The Trapezius: The Muscle That Moves Your Shoulders The trapezius muscle spans the neck, shoulders, and upper back, controlling posture, shoulder movement, and head stability. Key Functions of the Trapezius: Elevates the shoulders (shrugging motion). Retracts the shoulder blades for proper posture. Rotates and stabilizes the neck and head. Assists in arm movement by supporting the scapula. Anatomy Breakdown: Upper Trapezius – Lifts the shoulders and tilts the head. Middle Trapezius – Pulls the s