The Sense of Balance and the Inner Ear

In short: The sense of balance tells the brain how the head is positioned in space and whether it is turning or accelerating. Its sensory organ sits well protected in the inner ear, right next to the cochlea.

In more detail: The balance organ consists of three semicircular canals for rotations and two small sacs for gravity and straight-line acceleration. The brain combines these signals with information from the eyes and from muscles and joints.

In detail

• Location: The balance organ lies in both inner ears deep inside the temporal bone and, together with the cochlea, forms part of the so-called labyrinth (sinnesorgane-auge-ohr-nase).
• Semicircular canals: The three fluid-filled canals are set roughly at right angles to one another, so they can detect head rotations in any direction.
• Sensory cells: When the fluid in a canal moves, it bends tiny sensory hairs, and the sensory cells report this stimulus to the vestibular nerve.
• Otolith organs: In the two sacs, tiny calcium crystals rest on a jelly-like layer; thanks to their weight they register gravity, head tilt and straight-line acceleration, for example in a lift.
• Senses working together: Only by combining it with vision and with feedback from muscles, tendons and joints does the brain build a stable sense of the body’s position.
• A steady gaze: A fast reflex moves the eyes against every head movement so that the picture does not shake while you walk or run (reflexe-und-nervensystem).
• Dizziness after a roundabout ride: After spinning quickly, the fluid in the canals keeps moving for a moment, so the brain reports a rotation even though you are standing still.
• Motion sickness: When the signals from the eyes and the balance organ contradict each other, for example when reading in a car, nausea can result (reisekrankheit-kinetose-vorbeugen).
• Taking symptoms seriously: Frequent or sudden severe dizziness can have many different causes and should be checked by a doctor.