Which parts of the ear are responsible for:
Dynamic equilibrium?
Topic: Dynamic equilibrium
Answer
The SEMICIRCULAR CANALS.
DYNAMIC equilibrium is the balance of the body IN MOTION — during turning, spinning or any sudden change of direction.
The three semicircular canals lie in three planes at RIGHT ANGLES to one another, so movement in any direction disturbs the endolymph in at least one of them. Sensory cells in the swollen base of each canal (the ampulla) detect that movement of fluid and report it to the brain.
Because the canals lie in three planes, they register rotation in all three dimensions.
This also explains DIZZINESS after spinning: the fluid keeps moving for a moment after you stop, so the canals report a turn that the eyes contradict.
Note that the ear therefore does TWO unrelated jobs — HEARING (cochlea) and BALANCE (canals, utriculus, sacculus).