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How the Inner Ear Balance System Works - Labyrinth Semicircular Canals

Deep within each ear there is a balanced system called the labyrinth

composed of three semicircular canals. These semicircular canals are also

connected to the cochlea which is the organ that allows for hearing. Each

semicircular canal is responsible for sensing a particular head direction. Each

semicircular canal is filled with fluid and when displacement of this fluid

occurs within the canal, nerve signals are sent to the brain informing which

direction the head just turned. The posterior semicircular canal shown here

detects when the head tilts down towards the shoulder. The superior

semicircular canal detects when the head nods up and down in a yes motion.

The lateral semicircular canal detects when the head shakes side to side in a no

motion.

When a person is dizzy, one of the main tests performed to determine whether the

inner ear is the source of the dizziness is the Dix Hallpike maneuver shown here.

The head is turned 45 degrees and the body laid back such that the head is

extended about 20 to 30 degrees. If the right inner ear is causing a person's

dizziness, eye twitching called nystagmus will occur; a condition called BPPV.

Depending on how the eye twitches, specific head maneuvers can be performed

to potentially cure a patient of their dizziness.