Trapezius
Latin: M. trapezius sinistra
Location: Back
Paired structure: one on the left and one on the right side of the body.
View the trapezius in 3DOrigin
External occipital protuberance, superior nuchal line, ligamentum nuchae, spinous processes of C7–T12.
Insertion
Lateral third of the clavicle, acromion and spine of the scapula.
Action
Upper fibres elevate and upwardly rotate the scapula; middle fibres retract it; lower fibres depress it and rotate it upward. Working with serratus anterior it abducts the arm overhead.
Nerve supply
Spinal accessory nerve (CN XI) motor; C3–C4 proprioceptive.
Blood supply
Transverse cervical artery and dorsal scapular artery.
Clinical relevance
Trapezius palsy (accessory nerve injury in neck surgery) drops the shoulder and weakens overhead reach; chronic tension-type neck pain centres on its upper fibres — the classic desk-work knot.
Educational anatomy reference, not medical advice. About this content.