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What Is the Vestibular System?

In humans, the sense of balance is mostly maintained by the vestibular system, the sensory system that detects acceleration or changes in movement.
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  • Last Modified Date: 17 August 2014
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Equilibrioception, or the sense of balance, is a sense by which animals and humans receive information about their external or internal environments. In humans, the sense of balance is mostly maintained by the vestibular system, the sensory system that detects acceleration or changes in movement. The basic function of this system is to help prevent people from falling over while walking or standing still.

A significant component of the vestibular system is the labyrinth of the inner ear, where equilibrioception is determined by levels of fluid, which is called endolymph. There are two components of this system in the inner ear: the otoliths and the semicircular canal system. The otoliths indicate linear acceleration, and the semicircular canal system indicates rotational movement. Based on input from these components, the vestibular system maintains balance by sending signals to the muscles that keep the body upright and to the muscles that control eye movement.

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The importance of the auditory system in the greater vestibular system is evident by the fact that auditory problems, such as inner ear infections, can result in balance problems. Other components of the vestibular system include vision, the hands and fingers, and the pressors on the soles of the feet — all of which provide feedback to the vestibular system regarding spatial orientation, postural positions, and the presence of horizontal or slanted surfaces, among others. Additionally, the trigeminal nerve, which lies along the surface of the face and eyes and functions by carrying sensations from the face to the brain, is part of the vestibular system.

Disturbances of the vestibular system usually cause dizziness and nausea. Some of the common causes of balance disruption include inner ear infections, bad head colds, and certain medications or medical conditions. The rapid and sudden movements that may be experienced during certain activities, such as riding a merry-go-round, may also cause temporary dizziness. Also, alcohol can cause dizziness due to changes that occur in the viscosity of the blood and the endolymph in the inner ear labyrinth with alcohol consumption.

Other causes of vestibular dysfunction include inner ear disorders that cause swelling and irritation, such as vestibular neuritis and labyrinthitis. Additionally, dislodged movement-sensing crystals in the otoliths cause the sudden onset of dizziness associated with changes in head position, which is known as benign paroxysmal positional vertigo (BPPV). Serious medical disorders, such as brain stem injuries and brain tumors, can also cause vertigo and other associated symptoms.

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Emilski
Post 5

@jmc88 - I may be wrong on this, and hopefully someone will correct me, but I seem to remember reading something a long time ago about there being small hairs in our ears that detect the fluid level of the labyrinth and send that information to our brain.

As for the fear of heights, since it can be classified as a phobia, I think that means it is considered an irrational fear. I'm not sure I completely agree with all phobias being irrational since they probably arise out of human instinct to avoid dangerous situations like with heights, snakes, and spiders.

That being said, though, I wonder if there is a physical reaction to the heights that involves the vestibular system or if our brain just overreacts even though everything else in our body is telling us not to.

jmc88
Post 4

How exactly does the fluid in the labyrinth send information to the brain? What are the receptors that transfer the information?

Also, does anyone know what causes dizziness in people who are afraid of heights? When I was younger I never had a problem with heights. As I have gotten older, I have started to get dizzy or nauseous in certain situations.

Usually crossing a large bridge or even looking out the window of a tall building doesn't bother me, but if I'm walking or driving next to a steep drop, I start to have problems. I think as long as there is a solid barrier between me and the ground I feel fine. It's when the barrier isn't there that I get dizzy. Does anyone know what causes this and how it would relate to the vestibular system?

JimmyT
Post 3

@TreeMan - It sounds like you are having the same problem I used to have a lot. I finally figured out that it is called postural hypotension if you want to read more about it.

Basically, what it is is a decrease in blood pressure to your head when you stand or sit up. In my case, I work outside and was noticing it happening when I was leaning over and stood up. There are a couple possible causes. In my case, it was because I wasn't drinking enough water when I was outside, so I was kind of dehydrated, so there was less fluid in my system to build up the necessary pressure. I think different medications can be the problem, too.

You can try to drink more water during the day if you think that might be the problem. If that doesn't seem to be it, I would go to your doctor and see what he thinks.

TreeMan
Post 2

Sometimes if I am laying on the couch and sit up quickly or if I'm crouching and stand up fast I will get dizzy and everything goes white for a few seconds. Does anyone have any idea what that might be? I have never really felt like I am going to faint or anything, but I am too dizzy to start walking or anything. It has only started happening the past few months.

John57
Post 1

I was experiencing some vertigo and feeling light headed. It seemed to be worse when I would lay down and could feel the room spinning around.

If I turned my head too quickly I would also get dizzy and feel out of balance. I found out that I had an inner ear infection that was causing all these symptoms. This inner ear infection was affecting my vestibular system.

Having a bad ear infection can affect your balance more than what many people realize. My doctor said that one of the first things she checks when someone complains of feeling dizzy is their ears.

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