The inner ear also contains three fluid-filled loops, called semicircular canals, set at-right angles to one another. Any movement of the head affects the fluid in one or more of them.
The ends of the canals contain receptor cells that register movements of the fluid and pass the information to the brain.
The whole system of canals and cavities in the inner ear is called the labyrinth.
Disease or injury that causes malfunction of the labyrinth will cause vertigo, a sensation that the individual or the environment is spinning.
Another area of the inner ear, the saccule and utricle, contains sensitive cells with fine hairs that include small “stones” (otoliths) of calcium carbonate.
When the head is held upright, the otoliths press on certain receptors. If the head is moved, the otoliths press on other receptors. In this way, receptors register any position of the head and pass this information to the brain.
The sense of balance comes from a combination of movement and position of the head.