The upper trapezius is one of three divisions of the trapezius muscle in the upper back. A large muscle stretching from the back of the neck outward to the shoulders and midway down the back, the trapezius performs a number of functions in the upper body, depending on which section of the muscle is being activated. The upper or superior section is responsible for the elevation or shrugging of the shoulders and for carrying the weight of the arms.
Although it is one continuous muscle, the trapezius has three distinct sections: the lower, middle, and upper trapezius. It has a quadrilateral or diamond shape, with the inverted triangle of the lower trapezius, which runs from the middle-to-lower thoracic vertebrae upward and outward to the bottom inside edges of the shoulder blades, pointing downward from the shoulder blades toward the mid-back. The middle trapezius points outward, extending horizontally between the upper thoracic vertebra and the top outer edges of the shoulder blades. Above that is the triangle of the upper trapezius, attaching at its topmost point to the occipital bone at the base of the skull and spreading downward and outward to insert along the outer third of the back of the clavicle bone.
Because its fibers run obliquely, originating on the occipital bone and extending diagonally to the top of the shoulder girdle, the upper trapezius is positioned to pull upward on the shoulders and, in turn, the arms. The clavicle attaches via the acromioclavicular joint to the acromion process of the scapula, the large bony prominence felt at the peak of the shoulder above the glenohumeral or shoulder joint. Therefore, any upward pull on the clavicle also elevates the shoulders, moving the arms upward relative to the body.
The upper trapezius also works in opposition to the lower trapezius, which is the division of the muscle whose job is to depress or pull down the shoulder blades. Particularly in individuals who work in front of a computer, the upper fibers are often overdeveloped, so strengthening the lower fibers of this muscle while stretching the upper fibers is a recommended strategy for getting the tight upper trapezius to relax. Strengthening exercises like shoulder shrugs may still be included in an exercise routine but should be performed in conjunction with lower trapezius exercises to correct or avoid any trapezius muscle imbalances.
To stretch the upper trapezius, one should sit upright in a chair with the chin slightly tucked and right arm behind the back. Grasping the right hand in the left hand, gently pull the right arm down and to the left behind the back while slowly tilting the head to the left. Hold this stretch for 20 to 30 seconds and repeat on the other side. It is recommended that this stretch be performed twice daily, especially while seated at work in front of the computer, for optimum benefit.