Spin in a circle a few times and suddenly you’re imbalanced and wobbly. Keep going and you might find yourself on the ground. But why? What actually causes this sensation? The credit for that goes to your ears.
Your ears play a major role in your balance. Each one has 3 semi-circle canals that sense the movement of your head along a different axis. These canals work together to orient you in 3D space. Each canal is filled with fluid that sloshes around as you move, bending tiny hairs that cover the lining of the canal. As a hair bends, a signal is sent to your brain with information on the direction of the movement.
When you begin spinning, inertia causes the liquid to resist the movement, which causes the hairs to bend against the direction you are spinning. Information is sent to your brain that you are spinning. However, as you continue to spin the fluid adjusts to the movement and reaches a point when it is spinning with you. At that time there is no resistance, so the hairs straighten back out. Because the tiny hairs are back to their normal position, your brain is informed that you are no longer spinning.
Then you stop.
Inertia now causes the liquid to continue to move inside of your ear, bending the hairs in the direction that you were just spinning. Although you are now standing still, your brain is now receiving the information that you are moving.
That feeling is what we call being dizzy.