Anatomy

Origin

Lower part of ligamentum nuchae, spinous processes of seventh cervical vertebra (C7) and upper three or four thoracic vertebrae (T1–T4)

Insertion

Mastoid process of temporal bone and lateral part of superior nuchal line

Nerve

Lateral branches of dorsal primary divisions of middle and lower cervical nerves

Actions

Acting together, they extend, hyperextend head, neck; acting on one side, they laterally flex, rotate head, neck