Questions came up while discussing the auditory system the other day about parts of the ear (specifically, the otoliths, of which we have two on each side). I felt confident that these are a part of the vestibular system (along with the more familiar semicircular canals of which we have three on each side) and that they must not have anything to do with hearing because I had never heard of them. Since that time I've done a little reading on what makes up the vestibular system and I'm sharing info with you now. Just follow the links to any of the hot words in this ramble to learn more. This is the kind of thing that happens when you have a cognitive psychologist that knows a lot about memory talking about sensation. The main problem is that the term "inner ear" is very generic and refers to an area that contains parts of both the auditory and vestibular systems.
Figure 1 Human Labyrinth, from the left ear. It contains i) the cochlea (yellow), which is the peripheral organ of our auditory system; ii) the semicircular canals (brown), which transduce rotational movements; and iii) the otoliths (in the blue/purple pouches), which transducer linear accelerations. The light blue pouch is the endolymphatic sac, and contains only fluid.
If you want to learn more read the Vestibular System Primer!