The ear as a whole is sometimes called the vestibulocochlear organ because it not only enables the animal to hear but also gives it a sense of balance.

The mechanical stimuli produced by sound waves are transformed into nerve impulses in the cochlea, and the movement of fluid and the action of gravity on receptors within the vestibular apparatus provide the animal with a sense of the position and movement of the head. Both functions are performed in the internal ear, the most medial of the three subdivisions of the ear as a whole, the other subdivisions being the middle ear and the external ear. Only the external ear is visible in the intact animal; the other two are hidden within the temporal bone (Fig. 9.24/24).