Facet Joints and Nerves
Most of the bones of the spine have four joints, or places where they rub directly against other bones. These joints are called facet joints. Located on the extensions of bone off the back side of the vertebrae, these surfaces come in contact with those of the vertebrae directly above and below. Their purpose is to safely guide and restrict the movement of your spinal bones.
To get an idea of how the facet joints function, think of a door and doorstop. When a door opens so far that it hits against the stop, no further movement in that direction is allowed. In your spine, the bones move as far as the facet joints will allow them to before one bone forces another to stop. For example, when you stand and put your hands on your hips, bending as far backward as you can, it is the facet joints that help stop your backward movement. The same thing goes when you rotate your neck or back to the left or right as far as you can.
Located on the bony extensions of the vertebrae, the surfaces
of the facet joints fit together like a three-dimensional puzzle.
Without intervention, this condition can become chronic; bone spurs may even develop. Bone spurs are the bones' way of trying to grow together, or fuse, rather than remaining separate and moving freely. This condition can be extremely painful and may require surgery. However, it doesn't take such a serious condition to make these joints painful. If you've been standing on your feet too long, the facet joints end up getting compressed by the effects of gravity and the strain of supporting your upper-body weight, causing low-back pain even in healthy backs.
In the spaces between vertebrae run
the nerve roots—exits off the
spinal cord's information highway.
The nerves actually begin in the brain, your body's command center, and branch out through the spinal cord, which runs through the bones in your spine. The spinal cord is the main information highway in your body; all of the brain's signals to the body are carried through the spinal cord. Where the nerves branch off and leave the spinal cord, they are called nerve roots. Beyond this point, they are simply known as nerves.
The brain is always monitoring what is happening throughout the body and sending messages -- tiny amounts of electricity -- through the nerves. The various parts of the body can, in turn, send signals back to the brain regarding their condition. The feedback to the brain includes important sensations such as pressure, heat, cold, movement, and the big one, pain. If damage occurs to the nerves, communication breaks down, and many problems can arise with the organs that require instructions or that need to report sensations.
Clearly, the spinal cord is vital to the functioning of your entire body. All of the sensations and all of the organs from your neck to your toes rely on that one telephone line. The other structures of the back (bones, muscles, and ligaments) can protect this pathway if they are properly maintained, but poor posture and bad habits can weaken your back's protective ability. Indeed, sometimes injury or strain to a muscle or disk can even affect the nerve root or cord itself, actually causing a nerve injury. And damaged nerves are not only bothersome -- they hurt!
Putting It All Together
All of these spinal structures and tissues work together to allow you to bend, move, or do essentially anything. It is a complex system with complex functions. Not only does your back have to support a good deal of your body's weight and carry vital nerve signals to all of the parts of the body, but we ask it to bend and twist at the same time. It is an engineering marvel.
Even though your back is very versatile, it does like certain positions better than others; that is, it can tolerate some postures or poses better. Specifically, the back is most comfortable while lying down with its natural curves aligned. In general, for sitting or standing, the more you can keep your curves properly aligned, the better it is for your total spine.
Moving, bending, and twisting in limited ranges is healthy for all parts of the back. Limit the forward bending of your back to about 30 degrees; this is a fairly safe range. A similar range exists for twisting of the back; you should try to minimize twisting motions to each side. Remember also that staying for extended periods of time in bent, twisted, or any awkward positions dramatically increases the physical stress placed on the spine. Certainly, the worst thing you can do to your back is combine all of these single factors by repeatedly bending over with straight legs and a rounded twisted back, then picking up something heavy at arm's reach, and then staying in this position for an extended period of time.
Your spine and the related structures do benefit from movements that place acceptable levels of stress on them. Proper exercises can thicken, stretch, lubricate, and build the endurance of your back and strengthen its ability to withstand the forces of gravity in all of your movements. The most benefits are derived when these healthy movements are performed regularly. On the other hand, some people have problems with their backs because they have overdone it. They have performed the same movements too many times, and overuse has fatigued or injured certain spinal tissues.
However, no matter how many precautions you take, we all injure our backs now and again. If you have just injured your back -- maybe by lifting something that is too heavy -- our next page will give you some tips for dealing with the pain immediately after the incident.
This information is solely for informational purposes. IT IS NOT INTENDED TO PROVIDE MEDICAL ADVICE. Neither the Editors of Consumer Guide (R), Publications International, Ltd., the author nor publisher take responsibility for any possible consequences from any treatment, procedure, exercise, dietary modification, action or application of medication which results from reading or following the information contained in this information. The publication of this information does not constitute the practice of medicine, and this information does not replace the advice of your physician or other health care provider. Before undertaking any course of treatment, the reader must seek the advice of their physician or other health care provider.