Rectus capitis posterior major

The rectus capitis posterior major is a triangular-shaped short suboccipital muscle that connects the second cervical vertebra (axis; C2) with the occipital bone of the skull. Overall, it provides postural support for the head and acts at the atlanto-occipital and atlanto-axial joints. Moreover, it forms the superomedial border of the suboccipital triangle.

Check it out