Balance is an internal sense and relies on sensory
receptors that monitor the position of the head and body. Whether we are still
or moving, balance is essential for maintaining our posture and stopping us
falling over. The vestibule and semicircular canals of the inner ear provide
information on the position and movements of the head. Combined with signals
from the eyes, this helps us balance.
BALANCE APPARATUS OF INNER EAR
Turning movements of the head are picked up by sensory hair cells
embedded in structures called cupulae in the semicircular canals. Tilting
movements of the head, and its position, are monitored by hair cells within
structures in the vestibule.
These tiny crystals, called otoliths, are attached to sensory hair
cells in the vestibule. When the head tilts, the otoliths move, causing the
hair cells to bend and nerve signals to be sent to the brain.
