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.

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