trapezius /trəpē″zē·əs/ [Gk, trapezion, small table] , a large, flat, triangular superficial muscle of the shoulder and upper back. It arises from the occipital bone, the ligamentum nuchae, and the spinous processes of the seventh cervical and all the thoracic vertebrae. It acts to rotate the scapula upward; adduct, raise, or lower the shoulder; and retract the shoulder.
