THE VESTIBULAR SYSTEM
The vestibular system involves various organs:
- The organ of balance – this registers the movements of the head and its position when moving the body
- The eyes – eye movements stabilise the eyesight when moving the head. Thanks to this, the ‘movement’ of the surroundings is slowed down when moving, keeping you from falling over by dizziness.
- The muscle spindles in the muscles of the body – the muscles of the neck and the back contract in order to stabilise the head and the torso in the axis of the body. This axis functions as a reference to control the movements of our legs and arms. The touch, the pressure on the skin, the tension in the muscles, tendons and joints all provide information about our balance.
The entire balance system integrates all information about movements and positions coming from various parts of the body. The system makes it possible to react to every disturbance of our balance, whether voluntary or involuntary. Recovery of balance after a wrong step or of the eyes when turning around.
THE ORGAN OF BALANCE
‘Ear stones’ that lie on top of the hair cells
The organ of balance is found in the inner ear behind the petrous bone and consists of two parts:
- the three semi–circular canals.
- the two otolith organs.
The three semi–circular canals are perpendicular to each other: the front canal, the rear canal and the horizontal canal.
These canals contain liquid and hair cells.
Attached to these semi–circular canals are the otolith organs: utriculus and sacculus.
These are two small bags filled with liquid and hairs, just like the semi–circular canals. However, here a sort of stones are lying on top of the hair cells. These stones are called the statoconia.
The organ of balance sends information to the brains to help maintaining balance when standing still and while moving.
When you move your head, the liquid in the three semi–circular canals starts to move. The movement of the liquid also makes the small hair cells move. This movement of the hair cells in the organ of balance gives the brains information about our rotary movements, for example how you move your head in relation to your body.
The two bags or otolith organs on which the statoconia are lying, register pressure. The pressure on the statoconia while moving provides information about our linear movements. For example, when you are standing in a lift you ‘feel’ that you are going up or down.
All information is sent to the brains through the equilibrium nerve. There the information can be processed and be used to maintain your balance.
