Nearly every flexible or movable level of the spine (with the exception of the very top vertebra) is comprised of the same elements, including:

• Vertebral body, the bony building blocks of the spine
• Facet joint, small stabilizing joints located between and behind adjacent vertebrae
• Intervertebral disc, which provides a cushion between each of the vertebral bodies and binds them together

Other than supporting the organs of the entire body, the axial (midline) skeleton’s discs allow rhythmic motions required by humans to walk, run, swim, and perform other regular movements. Additionally, the spine (so named from the bony plates that extend backwards from the vertebrae) provides a bony protection for the spinal cord and emerging nerves.

Facet Joints and Flexibility

To prevent excessive motion, over-twisting, or toppling over, the segments of the spine are stabilized by a number of structures that nonetheless preserve the flexibility needed to turn, look around and get around.

The facet joints, or joints with “small faces” are found at every spinal level (except at the top level) and provide about 20% of the torsional (twisting) stability in the neck and low back. The vertebrae of the chest area are normally far less mobile and permit a small amount of forward/backward and some side bending, and very little twisting.