The vestibular system gets its raw information from the vestibular organs, which consist of three semicircular canals and the otolith organ. The three semicircular canals are oriented along the x, y, and z axes, and define motion on each of the three dimensions of space. When the head moves, hair cells (scilia) detect the motion of the fluids inside each canal. The brain uses this information to calculate changes in inertia, in much the same way that the inertial navigation system on an airliner senses changes in position and velocity. The otolith organ uses a pendulum-like appendage, the utricle, to orient the sense to the vertical force of gravity.

Because the vestibular system combines the inertial information from the three semi-circular canals with the gravitational orientation provided by the otolith organ, it is the basis of our inertial gravitational model of the world?that is, our model of the world as a three-dimensional space with a clear sense of up and down. As a child continues to develop in the womb, the other major brain systems (motor, tactile, auditory and visual) also develop, but they develop in relation to the vestibular system, or sense of balance.

Since the vestibular system plays such a key role in the foundation of perceptual abilities, balance problems can cause many, seemingly unrelated, problems in brain function.