“[Breuer’s] basic premise was that the semicircular canals sense angular movement of the head by movement of the fluid (endolymph) within them. The endolymph moves relative to the walls of the canals because of its inertia. Because the three semicircular canals are approximately at right angles to each other, the canals sense movement on all possible planes” (Baloh, Vertigo... p. 31).