The are three half-circular, interconnected tubes located inside each
Ear that are the equivalent of three
Gyroscopes located in three planes perpendicular.
The vertical canals are positioned at an angle of about 100 degrees relative to one another, while the horizontal canal makes an angle of about 95 degrees with the posterior canal and an angle of about 110 degrees with the anterior canal. Deviations up to 10-15 degrees between individuals are normal. Because the angles between the canals are not perpendicular, movements of the head stimulate horizontal and vertical canals simultaneously.
The three canals are:
Each canal is filled with a fluid called
Endolymph and contains a motion sensor with little hairs (
Cilia ) whose ends are embedded in a gelatinous structure called the
Cupula . On top of the hairs are tiny particles of calcium carbonate called
Otoliths . The cupula and the hairs move as the fluid moves inside the canal in response to an
Angular Acceleration . During this movement, the hairs are bent by the action of gravity on the otoliths, and the brain decodes the degree and direction of bend of the hair cells.
The Semicircular canals are a component of the
Labyrinth .
