At the atlanto-occipital joint, the joint between the neck and the skull, the rectus capitis anterior muscle takes care of flexing the neck, allowing the head to nod downward. This takes place at a low region on the back the skull.
The muscle originates at the atlas bone of the cervical vertebrae (the topmost vertebra) and inserts into the skull's occipital bone. This is near the basilar part of the occipital bone, and near the foramen magnum, the hole in the skull through which the spinal cord and column pass.
The first cervical spinal nerve (C1) innervates (supplies nerves to) the muscle. This nerve extends from the atlas bone. During its course, it extends upwards, servicing more than just the rectus capitis anterior muscle. The nerve also innervates the geniohyoid, the rectus capitis posterior major, and other muscles.
Damage, strain, or tears to this muscle could alter the neck's range of motion. However, compared to the other rectus capitis muscles, the rectus capitis anterior is relatively short. Injury to this muscle is not as likely as it would be with other muscles in the neck.