Spine and Back Anatomy: Understanding How the Back Works


Understanding How Your Back Works

The back (spine) is made up of the bones (vertebrae), spinal cord, nerves, muscles, ligaments, and the system that carries blood (blood vessels).  The vertebrae of the back protect the spinal cord. 

  • The top seven vertebrae make up the neck (cervical spine) and begin at the base of the head.
  • There are twelve vertebrae making up the upper and middle back (thoracic spine). 
  • The bottom five vertebrae of the spine make up the lower back (lumbar spine). The sacrum bone and tailbone (coccyx) are at the very bottom of the back.

In the healthy back, there is a disc filled with fluid between each vertebra. The disc helps to cushion the vertebrae from moving together under the weight of the body.  Some of the discs also allows the vertebrae to turn and move front-to-back, side-to-side and left-to-right.

The discs between the vertebrae have a strong outer ring (annulus fibrosis). The outer ring helps keep the disc’s soft center (nucleus pulposus) in place. 


The Unique Job of the Neck (Cervical Spine)

The bones and the discs in the neck help support the weight of the head and allow a healthy cervical spine to:

  • Bend side-to-side (lateral bend) (Figure A).
  • Bend forward-to-back (flexion and extension) (Figure B).
  • Turn left-to-right (rotation) (Figure C).

The Unique Job of the Mid Back (Thoracic Spine)

Each thoracic bone (vertebra) connects with a rib to provide stability and protect the organs, like the heart and kidneys.  The mid back has very limited movement.


The Unique Job of the Lower Back (Lumbar Spine)

The lower back carries the weight of the upper body and helps absorb the forces caused by movement.  The healthy lower back allows forward-to-back bending and some rotation.

Results are not necessarily typical, indicative, or representative of all recipient patients.  Results will vary due to health, weight, activity and other variables.  Not all patients are candidates for every product or procedure.  Only a medical professional can determine the treatment appropriate for your specific condition.   Appropriate post-operative activities will vary from patient to patient.  Talk to your surgeon about whether surgery is right for you and the risks of the procedure, including the risks of infection, implant wear, loosening, breakage, or failure.  For additional information or to find a surgeon near you visit www.zimmerbiomet.com
All content herein is protected by copyright, trademarks and other intellectual property rights, as applicable, owned or licensed to Zimmer Biomet or its affiliate unless otherwise indicated, and must not be redistributed, duplicated or disclosed, in whole or in part, without the express written consent of Zimmer Biomet.