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Cerebellum
The Cerebellum is a peach-sized structure
situated at the base of the brain. It is
highly-folded and has been called the brain with the brain -
indeed the very name comes from the Latin for "little brain".
See this diagram:
 The cerebellum is responsible for
coordinating movement, planning, motor activities, learning and remembering of
physical skills and for some cognitive abilities. Interestingly, the size of
this brain region within any mammal species is a good indicator of its the
physical capability.
The cerebellum controls
movement by collecting sensory nerve inputs, such as limb position, balance
information and vision, and synthesising them together to control movement by
sending nerve transmissions down motor nerve outputs. The learning of physical
tasks is done by trial and error and then stored into cerebellar memory. This is
the reason that we never forget certain skills such as riding a bike. There is
some evidence that mental activities are also co-ordinated in the cerebellum
which could explain why
cognitive
dysfunction is sometimes associated with damage to the cerebellum.
The cerebellum is divided
into two hemispheres by the central "vermis". The surface of each hemisphere is
made up of grey matter
surrounding a large mass of white matter (nerve
cells with axon). The whole
structure is connected to the rest of the central
nervous system by three very broad tracts of white matter called the
cerebellar peduncles. These are the brachium pontis which connects to the
pons, the restiform body
which connects to the
medulla and the brachium conjunctivum which connects to the mesencephalon.
Damage to the cerebellum or
the cerebellar peduncles is very common in multiple
sclerosis. This is not surprising given the large amount of white matter in
these structures.
Some of symptoms associated
with damage to the cerebellum or the nervous tracts leading to it are:
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Dysdiadokokinesia (difficulty in performing rapid alternating movements)
-
ataxia (difficulty in
coordinating movements)
-
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loss of balance and
vertigo
-
muscle weakness
-
dysarthria (loss
of coordination of the muscles controlling speech)
-
loss of postural tone.
Cerebellum links:
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