Monday, November 12, 2012

Weebles wobble, but they don't fall down...


Unlike weebles, we have very complex means for staying upright.  There are three main systems in the body that contribute to our ability to maintain balance.  They are vision, the vestibular system, and joint/muscle receptors.  Vision is obviously important for maintaining balance, but the other two systems have important roles as well.  The vestibular system, located in the inner ears, helps your body know which way is upright and, with vision and joint receptors, if your body is moving and how so (as in rocking on a boat).  Joint receptors, along with receptors in the muscles, tell your brain where the joint is in space and if and how your joint is moving.  Additionally, sensory input from the skin helps us feel the ground and adapt to uneven surfaces.  Processing, integration, and control from brain centers (for instance, the cerebellum, located under the base of the skull in back) play a major role in maintaining balance.  If something goes wrong in any of the systems, balance will be affected and you'll have to rely more on the other systems.

A few practical examples illustrate the contributions of the various systems.  A person who's had a knee replacement has lost joint receptors in the parts of the joint that were removed in surgery.  Sometimes the loss is significant enough that balance is affected because the person can't tell where the joint is in space very well.  People with diabetes often loose sensation in there feet due to nerve damage from the disease.  They are basically walking on two numb feet, which can be especially troublesome with walking on the lawn (which is uneven).  A person who had a blow to the head may find that they are terribly dizzy with changes in position.  This can be due a problem with the sensory apparatus in the inner ear, but is often treatable.

The balance system is really a combination of beautifully interworking systems in the body.  So, next time you take a step without falling down, be glad everything's in working order!
-Karen

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