Anatomy

Origin

Medial third of superior nuchal line, external occipital protuberance, ligamentum nuchae, spinous processes and supraspinous ligaments of seventh cervical vertebra

Insertion

Posterior border of lateral third of clavicle

Nerve

Accessory (eleventh cranial), C3, C4

Actions

Elevates scapula, stabilizes scapula against downward rotation, as when weight is carried in the hand. Upper and lower parts together rotate scapula (important in elevating arm)