How does the sense of balance differentiate between head and body tilting?

From my limited understand of balance, a large part of it comes from an organ in the ear which detects the movement of fluid in differently oriented canals. The fluids move depending on gravity and acceleration, and the brain gets information that it uses to keep it’s balance.

How does the sense make out the difference between tilting your whole body and tilting only your head? Wouldn’t those have a similar effect on the ear fluid system? If I tilt my body to the right and my head to the left, the fluids in my ear would be the same as if I was just standing upright. Is that information combined with signals from the muscles to get a clear idea of the situation or does the information come from somewhere else?

There are a few things your brain uses to keep your balance. The fluids in your inner ear are only part of it and they themselves can’t distinguish between your head tilting or your whole body tilting. Proprioception, the ability of your body to sense where its bits and pieces are in relation to itself is also a big part of balance. It is what enables you to touch your finger to your nose with your eyes closed and in the example you give of just your head tilting, it is how your body knows to take into account your head position into the whole balance picture.

Basically, this is it. In addition to this, proprioception in the body itself probably allows the body to perceive gravity to a certain extent, although it will be less accurate than the inner ear.

By the way, the canals are not sensitive to gravity: they detect rotations. It is another part of the inner ear, the otoliths, which detect gravity.

My bits and pieces are always in the same place relative to the rest of my body…

I am convinced that another major pair of balance organs are . . .

( . . . wait for it! . . . )

. . . your ankles!

Especially when standing up, you can really feel it in your ankles if you start to lean a little in any direction. If you ever get contradictory messages from your ears and your ankles, you will definitely notice the confusion.

(I tend to notice this most clearly when I am standing in the shower, with my hair full of shampoo and my eyes closed.)

And the toes!