Vestibular System

The vestibular system in the brain does more than just allow us to stand upright, maintain balance and move through space.  It coordinates information from the vestibular organs in the inner ear, the eyes, muscles and joints, fingertips and palms of the hands, pressors on the soles of the feet, jaw, and gravity receptors on the skin and adjusts heart rate and blood pressure, muscle tone, limb position, immune responses, arousal and balance.

Dysfunctions in the vestibular system can cause anxiety or panic attacks, a need for self-stimulation, abnormalities in muscle tone, difficulty defacating, teeth grinding and chin tapping, hand flapping, academic problems, drooling, etc. Exercises that activate a wide range of inputs to the vestibular system have been found to be effective in reducing or eliminating vestibular problems.

Vision is an important component of the vestibular system. About twenty percent of visual neurons respond to vestibular stimulation (e.g. when spinning, head shaking, or rocking).   Adults who have suffered damage to the vestibular organs of the inner ear can learn to depend on visual information to maintain their balance.  However, If that visual information is removed or distorted (e.g. in the dark, or when there is conflicting visual information about the horizon, as when standing on a balcony), the individual will feel as if they are drifting or falling.

The auditory system is also highly involved in vestibular functions. The vestibular and auditory nerves join in the auditory canal and become the eighth cranial nerve of the brain.  Anything that disrupts auditory information can also affect vestibular functioning.   Blocked eustachian tubes in the inner ear, for example, create mild balance problems.

There are also other systems that provide sensory information to the vestibular system. The hands and fingers, for example, send information to the brain about the relationship between the body and stationary surfaces in the environment.  If the brain loses information from the vestibular organs of the inner ear (e.g. when there is fluid in the eustachian tubes) balance can be maintained by simply touching a vertical or horizontal surface with the fingertips.

The pressors on the soles of the feet provide important information to the vestibular areas of the brain about the texture of the ground.  This information is used to calculate weight and posture adjutments that will allow upright balance and movement.

The facial or trigeminal nerve (which lies along surface of the face and eyes) and the masseter muscle of the jaw also respond to vestibular information.  Chin tapping, for example, provides vestibular stimulation and vestibular stimulation innervates the masseter.