The earliest human known to have the capability of walking erect on two legs is Sahelanphropus, who lived 6 million years ago. The ability to stand erect led to required extensive changes in the human skeleton, including significant changes in the cervical spine. In modern humans, the cervical spine holds the head upright and gives it great mobility. The combination of great mobility in this spinal segment combined with the requirement that it carry significant weight makes the cervical spine susceptible to a wide variety of pathologies. The cervical spine not only supports the head upright,...