Alar ligaments

The alar ligaments, or check ligaments, are thick fibrous cords that attach the dens (odontoid process) of the axis (second cervical vertebra) to the occipital condyles of the skull.  They limit (or “check”) side to side movement of the head relative to the neck.  The figure below is a posterior view of the vertebral canal with the spinal cord removed.  The dens is covered by the cruciate ligament, and the alar ligaments can be seen just anterior to the cruciate ligament.