ANATOMY AND ACTIONS OF THE TRAPEZIUS MUSCLE

Dissection studies revealed the fascicular anatomy of the trapezius. I ts occipital and nuchal fibres passed downwards but mainly transversel y to insert into the clavicle. Fibres from C-7 and T-1 passed transver sely to reach the acromion and spine of the scapula. Its thoracic fibr es converged to the deltoid tubercle of the scapula. Volumetric studie s demonstrated that the fibres from C-7, T-1, and the lower half of li gamentum nuchae were the largest. The essentially transverse orientati on of the upper and middle fibres of trapezius precludes any action as elevators of the scapula as commonly depicted. Rather the action of t hese fibres is to draw the scapula and clavicle backwards or to raise the scapula by rotating the clavicle about the sternoclavicular joint. By balancing moments the trapezius relieves the cervical spine of com pression loads.