THE VESTIBULAR SYSTEM estimates body position and motion through the inner ear, body sensation, and visual systems. It detects motion of the head in space and in turn generates reflexes that are crucial for our daily activities, such as stabilizing the visual axis (gaze) and maintaining head and body posture.
The vestibular system is comprised of 2 types of sensors:
- Otolith Organs (the saccule and utricle) which sense linear acceleration
- 3 semicircular canals, which sense angular acceleration in 3 planes of gravity
There are 3 central reflexes called the vestibulo-ocular reflex (VOR), the vestibulocollic reflex (VCR), and the vestibulospinal reflex (VSR). The VOR generates eye movements while the head is in motion, if your world is blurry while you are moving around but clear while you are still you could have a problem with this reflex. The VCR acts on the neck musculature to stabilize the head, this is a compensatory response to what the vestibular system senses. The VSR generates compensatory body movement to maintain head and postural stability, this helps prevent falls. The vestibular system processes all of this information from our vestibular input, visual system, and proprioception (position sensation). The receptors send information along the vestibular nerve to the brain where that information is processed. After it is interpreted, it controls eye movement, posture, and balance.
This all happens in a split second and most of the time we do not even realize all of this is taking place. When these things work well together we have a sense of balance and stability and often times take that for granted. But, when a vestibular system isn't working properly we quickly become aware of what it does.