As shown in the diagram above, Otoconia crystals "ear rocks" break away from the Utricle in the inner ear and can become displaced in one of the semi-circular canals. The canal that is normally effected by the Otoconia is the Posterior semi-circular canal as shown in the diagram above. When someone changes their head position, the fluid in the semi-circular canals called Endolyph, flows through the canals and excites hair cells located at the end of the canals called the Cupula, which sends signals to your brain indicating your head is moving and your body is in motion.

When someone has Otoconia disrupting the flow of the endolyph fluid, your brain gets confused as to the degree of motion you are moving, because one side of your ear system Endolyph fluid is flowing at a different rate then the other side becasue of the Otoconia changing the saturation of the fluid. Your brain thinks your head is in constant motion because the the disequilibrium, which creates the motion sickness like symptoms and sometimes vertigo.