The trapezius is an extrinsic muscle of the shoulder. It is a broad, flat and triangular shape – forming a trapezoid shape in combination with the contralateral side.
- Attachments: Originates from the skull, nuchal ligament and the spinous processes of C7-T12. The fibres attach to the clavicle, acromion, and the scapula spine.
- Actions: Abduction of the upper limb at the shoulder (by rotating the scapula). The upper fibres of trapezius also elevate the scapula, the middle fibres retract, and the lower fibres depress.
- Innervation: Accessory nerve
- Blood supply: Transverse cervical artery
