How Your Balance System Works
Wednesday, June 1, 2011
Your sense of balance comes from many different systems working together to maintain the stability of your body and your vision. Good balance depends on correct information from several systems within your body, proper use of that information by your brain, and the right response from your muscles.
Where Does the Brain Get the Information It Needs?
Sensory information comes to your brain from your visual, somatosensory, and vestibular systems:
- Visual system: Your vision provides important information to the brain about your environment, such as where your body is in relation to the horizon while you're still or moving.
- Somatosensory system: You have special sensors sensitive to stretch, pressure, vibration, and touch in your muscles, tendons, joints, and skin that help your brain to know how your body is positioned.
- Vestibular system: Balance organs in your inner ear tell the brain about the movements and position of your head. This system senses your head movement and keeps your eyes focused. It also can tell the brain when your head is moving in a straight line (like when you're riding in a car or going up or down in an elevator) and also can sense the position of your head (upright or tilted) even when it is perfectly still.
The Brain's Role
Information from all of these systems travels to the brain stem. The brain stem also gets information from other parts of the brain, mostly about previous experiences that affect your sense of balance. Your brain can control balance by using the information that is most important for a particular situation. For instance:
- In the dark, when the information from your eyes is reduced or might not be accurate, your brain will use more information from your legs and your inner ear.
- If you are walking on a sandy beach during the day, the information coming from your legs and feet will be less reliable, and your brain will use information from your visual and vestibular systems more.
Once your brain stem sorts out all of this information, it sends messages to the eyes and other parts of your body to move in a way that will help you keep your balance and have clear vision while you are moving.
Acknowledgments: Shannon L.G. Hoffman, PT, DPT, and APTA's Neurology Section