Trapezius - Podcast Version 0:00 / 0:00 1x 0.25x 0.5x 0.75x 1x 1.25x 1.5x 1.75x 2x 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 By TeachMeSeries Ltd (2026) Fig 1The superficial muscles of the back Pro Feature - 3D Model You've Discovered a Pro Feature Access our 3D Model Library Explore, cut, dissect, annotate and manipulate our 3D models to visualise anatomy in a dynamic, interactive way. Learn More Pro Feature - Dissection Atlas The superficial and intermediate muscles of the back The superficial and intermediate muscles of the back You've Discovered a Pro Feature Access our Dissection Image Library Enhance your understanding with high-resolution dissection images showcasing real-life anatomy. Learn More Frequent questions What is the trapezius muscle and its shape? The trapezius is an extrinsic muscle of the shoulder, characterised by its broad, flat, and triangular shape, resembling a trapezoid when combined with the opposite side. Where does the trapezius muscle originate? The trapezius muscle originates from the skull, the nuchal ligament, and the spinous processes of the cervical and thoracic vertebrae, specifically from C7 to T12. What are the main actions of the trapezius muscle? The trapezius muscle facilitates the abduction of the upper limb at the shoulder by rotating the scapula, while its upper fibres elevate the scapula, middle fibres retract it, and lower fibres depress it. How is the trapezius muscle innervated? The trapezius muscle is innervated by the accessory nerve, which is essential for its motor function. What is the blood supply to the trapezius muscle? The blood supply to the trapezius muscle comes from the transverse cervical artery, ensuring adequate oxygen and nutrients for its function. Rate This Article