Sense of balance
We use our sense of balance to orient ourselves in the world.
made with this sense let you know what is up and down, left and right,
front and behind, above and below. The sense of balance perceives the
smallest changes in your vertical position.
Your body has a dynamic equilibrium. You maintain your balance by
very small adjustments in muscle tension in muscles all over your body.
Every time you stand up you have to rediscover your balance, by using
Your organ of balance is not the only organ that you use to maintain
your balance. Your eyes are at
least as important to orient yourself in your surroundings. Your eyes
see vertical and horizontal objects
which confirm the information given by your organ of balance. Try
walking in a room where everything is
at odd angles. Your balance could be so distorted, that the surface of
the water in a bucket (which is in
fact always horizontal) would appear to be sloping downhill.
The organs for
balance and hearing
The organ of balance is situated in the petrosal bone and is made up of
three semi-circular canals which
are perpendicular to each other, and the sacculus and utriculus. The
three semi-circular canals
are filled with a fluid that moves with every movement of your head,
thus registering changes in direction.
Because they are at right angles to each other, they can perceive
movement in every direction.
The sacculus and utriculus perceive the linear position and linear
displacement. In the sacculus, a gel-like
substance with a calcule made of calcium-carbonate crystals rests on a
horizontal layer of sensory cells.
During vertical acceleration or deceleration, such as in a lift, the
sensory cells detect a change in pressure
from the calcule. At constant speed, the pressure on the sensory cells
is constant, so you do not notice it.
The utriculus also has a calcule, but it is situated against a vertical
layer of sensory cells. These cells
detect changes in horizontal acceleration, such as when a car
accelerates or pulls over. Again, constant
speed is not detected.
Together, the three-dimensional planes in the organ of balance cover
all the degrees of movement in the joints. Ankle,
knee, elbows, shoulder and jaws are in the same plane as the organ of
When you observe other objects, you are using your organ of balance
in different ways. First, to determine the position of the object in
surroundings, taking the horizon as your orientation. Secondly, to
observe whether something is standing straight up, or leaning, and
whether something is actually horizontal or only seems to be. You can
detect how far something is out of true. Finally, using your organ of
balance you can detect whether something is out of proportion, e.g.
whether length is in proportion with height.
The organ of
balance and the joints
Spin someone around a few times while holding him, and observe his eye
movements. Keep holding
him after you stop spinning him. What is his balance like after having
been spun around? What
observations can you make, and what observations did the subject make
during and after spinning?
How does he perceive his surroundings?
Do this exercise again with another subject, but this time let the
subject go after spinning. What
observations can you make now?
Blindfold yourself and then try to balance while standing on one leg.
Then do it without a blindfold.
What is the difference?
Find some trees whose trunks rise almost straight up, but not quite.
Observe these trees, and
determine what would be the ideal position or angle of the tree-trunk.
Repeat this exercise with
observations of branches. An excellent tree for this exercise is a
mature beech whose branches bend
down low to the ground.
Record the length, height and girth of various mammals. How do these
measurements relate to each
other? Can you make any statements about the harmony of these