The trapezius is a large, roughly diamond-shaped muscle of the upper back, responsible for rotation of the neck, as well as elevation, adduction, and rotation of the scapula. Anatomically, the trapezius is a single muscle. Functionally, it is often treated regionally, with a variety of shrugs, rows, and other trapezius exercises employed to individually train the upper, middle, and lower fibers of the muscle.
Upper fibers of the trapezius originate at the base of the skull and attach to the clavicle. This region of the trapezius controls movement of the neck and shrugging of the shoulders. Upper trapezius fibers are commonly tight and strained among office workers and professional drivers due to extended periods of work-related tension in the muscle. Training and stretching of the upper trapezius can often reduce the severity of neck pain and stiffness particular to those professions.
Barbell and dumbbell shrugs are popular trapezius exercises for working the upper fibers. Upright rows and lateral raises will also target the area. Less well known, a medieval-looking device known as a head harness allows weighted resistance training for the neck itself. Alternatively, pressing the head against a resistance — the palm of the hand, for example — will work the same muscles as the head harness on a lighter scale. To stretch the upper trapezius, the simplest method is often to angle the head forward or to the side until a stretch is felt.
Middle trapezius fibers originate at the spinous processes at the middle of the upper back, and attach to the scapula, or shoulder blade. Trapezius exercises targeting these fibers involve the elevation, adduction, and upward rotation of the scapula. Rowing exercises work this area well, as do lateral raises in either the upright or bent-over position. Appropriate stretches for the middle trapezius include the fixed bar back stretch and, in yoga, the child's pose.
Lower trapezius fibers function in the adduction and depression of the scapula, movements that are also associated with the latissimus dorsi. Chin-ups, lat pull-downs, and seated rows can all function as trapezius exercises to target the lower fibers. Stretching this portion of the muscle is usually accomplished using similar positions as middle trapezius stretches, as well as any general back-of-body stretch.
Performing the heavy pulling movements used during many trapezius exercises can potentially induce back injury, and should be attempted with caution. Many heavy lifters employ the use of a weight belt to add support to the core region, or careful posture controls for the same purpose. In either case, the goal is to prevent rounding of the back, a habit that can result in serious injuries such as muscle tears and herniated discs.