inner ear illustration showing semicircular canal, hair cells, ampulla, cupula, vestibular nerve, & fluid

The semicircular canals are three half-circular, interconnected tubes located inside each ear that are the equivalent of three gyroscopes located in three planes perpendicular (at right angles) to each other. An illustration of the semicircular canal and associated structures. ... An illustration of the semicircular canal and associated structures. ...

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. The cupula and the hairs move as the fluid moves inside the canal in response to an angular acceleration. Endolymph is the fluid contained in the membranous labyrinth of the inner ear. ...