The spine is composed of 33 individual bones, called vertebrae, that interlock with each other to form the spinal column. Each vertebra in your spine is perfectly spaced and cushioned by an intervertebral disc, preventing these bones from rubbing together. In today’s post we discuss how these bony structures and their softer, flexible counterparts contribute to a healthy spine.
Collectively, the vertebrae make up the bony, interlocking building blocks of the spine. The bones are stacked atop one another and securely attached with a spinal disc in between each one.
The vertebrae have three main functional components:
- The vertebral body is for load-bearing and supports about half of the weight of the body, with the other half of our body weight supported by the muscles.
- The vertebral arch protects the spinal cord and nerve roots.
- The transverse processes, small bony structures on the right and left side of each vertebrae, are where ligaments, muscles and ribs attach.
Anatomy of a Vertebra
Vertebral body – A cylinder-shaped section of bone at the front of the vertebra. It is the main weight-bearing section of the vertebra.
Vertebral canal – The channel through which the spinal cord travels.
Pedical bones – The bony structure that connects the vertebral body to the lamina.
Lamina – The lamina create the outer wall of the vertebral canal, covering and protecting the spinal cord.
Spinous & transverse processes – The structures that provides an attachment point for the muscles and ligaments that stabilize and move the vertebrae.
Articular Facets – The facets are the cartilage-covered joints where each vertebra connect with the vertebra above and below it.
In order to understand how the vertebrae and disc work together, we must also know how a spinal disc functions.
The Spinal Disc
The vertebral discs are the tough, elastic bodies between the vertebral bodies. The discs have three primary functions:
- They act as tough ligaments that hold the vertebrae of the spine together.
- They act as a shock absorbers in the spinal column, positioned between each bony vertebra.
- They are cartilaginous joints that allow for the flexibility of the spine.
Anatomy of a Vertebral Disc
Vertebral discs are composed of two parts: a tough outer section and a softer inner core, and the configuration has been compared to that of a jelly doughnut.
Annulus Fibrosus – The outer section of the disc. It is the tough circular exterior composed of concentric sheets of collagen fibers (lamellae) that surround the inner core.
Nucleus Pulposus – The inner core. It contains a loose network of fibers suspended in a mucoprotein gel.
The outer section and inner core of the spinal disc fit together like two cylinders. The outer section of the disc has cartilage end-plates that firmly attach the disc to the vertebrae above and below.
At birth, about 80 percent of the disc is composed of water. In order for the disc to function properly, it must be well hydrated. The nucleus pulposus is the major carrier of the body’s weight and relies on its water-based contents to maintain strength and pliability.
The Vertebrae and Disc Together
These two separate components of the spine — the vertebrae and the discs — fit together to allow for both strength and mobility. The body needs both to be able to hold its own weight and move without too much rigidity. Because there are so many components involved, injury or degenerative disc disease, can throw the whole system off and cause far-reaching symptoms and disorders, such as spondylolisthesis.
If you or a loved one may have a spinal condition or injury to your vertebrae and disc, please contact us today to schedule an appointment with a board certified, fellowship trained spine specialist.
This site is not designed to and does not provide medical advice, professional diagnosis, opinion, treatment or services to you or to any other individual. Through this site and links to other sites, DISC of Louisiana provides general information for educational purposes only. The information provided in this site, or through links to other sites, is not a substitute for medical or professional care. You should not use this information in place of a visit, call consultation or the advice of your physician or other healthcare provider. DISC of Louisiana is not liable or responsible for any advice, course of treatment, diagnosis or any other information, services or product you obtain through this site.