Rachna is an expert gymnast on the balance beam. She has been vigorously practising for the Olympic Games. Lately, she has been experiencing dizziness and losing her balance during the practice sessions.
Which part of the membranous labyrinth is responsible for maintaining the body balance on the beam?
Topic: Semicircular canals
Answer
The SEMICIRCULAR CANALS.
The three semicircular canals lie in three planes at right angles to one another, so that movement of the head in ANY direction disturbs the endolymph in at least one of them. The sensory cells in their swollen bases (the ampullae) detect that movement and signal it to the brain.
Because they lie in three planes, they can register rotation in all three dimensions — which is exactly what a gymnast on a beam depends on.
Note that the ear therefore has TWO quite separate functions: HEARING (cochlea) and BALANCE (semicircular canals, utriculus and sacculus). Questions often test whether you know the second.