Page 22 - The Miracle of Electricity in the Body

20 THE MIRACLE OF ELECTRICITY IN THE BODY

Motor cortex
Motor neuron
Purple: The cortex of
the brain sends mes-
sages for the muscles
to go into action.
Blue: The sensory cells Main nerve
that direct movement in nodes (re-
the muscle send sig- sponsible for
nals to the cerebellum. complex
movements)
Red: The cerebellum
sends signals to the White matter
cortex, by way of the
thalamus, in order for Thalamus
the movement to take Gray matter
place. Cerebellum
Green: The cerebellum
sends messages direct- Brain stem
ly to the muscles by
way of the spinal cord.

One reason why you can use your
hands to do things is that your ner-
vous system has a flawless struc-
ture. Even picking up a marble is ac-
tually a very complex movement.
Delicate adjustments are required,
such as how far the fingers need to
be opened and how much force
should be applied. If the nerves did
not reach your hand, or if there were
no link between the nerves and the
brain, your hand would be a mere
assemblage of flesh and bone.