Sitting in deep within your skull, alongside your snail-shaped hearing organs, are your inner-ear balance organs, also called your vestibular system.
To begin to understand what your vestibular system does, perform this simple experiment: Hold your finger out in front of your face at arm’s length. Now shake your head back and forth while looking at your finger. You can keep the finger in fairly good focus, can’t you? Now hold your head still and move your finger very quickly. You will see that it is much, much harder to keep a good focus on your finger. The clear focus that you are able to keep on your finger during the first part of this experiment demonstrates the incredible efficiency of your vestibular system.
Your vestibular organs sense the position and motion of your head. They are hooked up to a reflex arc in your brainstem that controls the position of your eyes. As you move your head, your brainstem automatically moves your eye muscles to keep them on your finger. We believe that the “purpose” of this arrangement is to stabilize gaze and allow us to keep things in focus while we are moving.