Most of the motion of the spine is present in the neck (cervical) and lower back (lumbar). The thoracic area of the spine is generally stiff as it is connected to the ribs that are stabilizing structures. There is an advantage to stiffness as the thoracic area rarely degenerates.

The bones of the neck (cervical spine) consist of two different areas. The higher (superior) area makes up the skull base, C1 (Atlas) and C2 (Dens). The shapes of the skull base, C1 and C2 are very different from every other level of the spine. Their function is different as well.

The lower area C3, C4, C5, C6, C7 is comprised of five bones (vertebrae) that are very uniform or similar in shape and function.

The motion of the neck is made up of rotating your neck around as if turning to see something on the side of your head, nodding your neck up and down as if gestering yes and no for English speakers (flexion/extension) and bending the neck by making the ear move towards the shoulder.

Half of the normal rotation and flexion takes place from the upper portion of the neck or from the skull base to C2.