It is part of the shoulder girdle as it originates at the occipital lobe at the back of the skull and spans the neck, shoulders, and back. It spans the ligaments on either side of the seven cervical (neck) vertebrae (ligamentum nuchae), and the seventh cervical and all thoracic vertebrae.

It attaches at insertion to the posterior of the clavicle (collar bone) and on the spine of the scapula (shoulder blade) although the muscular fibers from C7 and T1 which pass transversely to reach the acromion and spine of the scapula help to elevate the scapula.

Its thoracic fibers converge to the Deltoid tubercle of the scapula. The action of these fibers is to act to elevate the scapula by drawing the scapula and clavicle backward, then to raise the scapula by rotating the clavicle about the sternoclavicular joint. By these balancing moments the Trapezius relieves the cervical spine of compression loads. It has a chief function which is to support the shoulders and the limbs and rotation of the scapula which is necessary to lift the arms above the shoulder level.

Functional regions of the Trapezius:

• the Superior Region (Descending)

• The Intermediate (Transverse)

• The Inferior (Ascending)

The superior descending part is what supports the weight of the arm. The intermediate transverse part is what helps retract the scapula on either side of the back, and the inferior ascending part is where the rotation and depression of the scapula takes place.