The Pons and Cerebellum
The Pons
• The pons is a section of the brain
stem that lies between the
midbrain and the medulla
oblongata
• Visually it looks like an enlarged
section of the medulla oblongata
• It’s the “butt” of the brain stem
• However the actual structure of
the pons and its function are
quite different
The Pons
• The cerebellum lies dorsal to the
pons
• The pons links the cerebellum
with the midbrain,
diencephalon, cerebrum,
medulla and spinal cord
The Pons
• The pons serves as the gateway
between sections of the brain
• It also has several other important
functions
• These include sensory visceral and
somatic organ control, motor
visceral and somatic organ control
and coordination of signals during
sleep
• The pons is directly responsible for
the stage of sleep called REM sleep
Video
• https://www.youtube.com/watc
h?v=mNdRoeVthVM
• https://itunes.apple.com/us/app
/sleep-cycle-alarmclock/id320606217?mt=8
• Interesting App…
Components of the Pons
• The pons contains four different
types of components
• 1) Sensory and motor nuclei of
control nerves
• These enervate the jaw, the
anterior surface of the face, one
of the eye muscles and sense
organs of the internal ear
Components of the Pons
• 2) Nuclei involved with the
control of respiration
• On each side of the pons, the
reticular formation continues
from the medulla
• The section in the pons has
control centers that help the
section of the medulla that
controls respiration
Components of the Pons
• 3) Nuclei and tracts that process
and relay information sent to or
from the cerebellum
• This is the section of the pons
that we talked about earlier
• It links the pons to the brain
stem, cerebrum and spinal cord
• This is how it relays information
to higher sections of the brain
Components of the Pons
• 4) Ascending, descending and
transverse tracts
• These are sections of nerves that
connect the pons to the
cerebellum
• These nerves connect the nuclei
of the pons to the cerebellar
nerves
The Cerebellum
• The cerebellum is the autonomic
processing center of the brain
• It is also the site of processing
for voluntary movement
• This means it coordinates
activities such as staying
balanced with activities such as
running
The Cerebellum
• The cerebellum is the most
identifiable part of the brain due
to its highly folded structure
• Folia are complex folds that
cover the cerebellum surface
• These are used to create a
higher surface area and allow for
a larger number of nerves in the
cerebellum
The Cerebellum
• The cerebellum is divided into
two lobes, the anterior and the
posterior lobes
• These lobes are identified by
their position in the cerebellum
• The lobes are separated by the
primary fissure
The Cerebellum
• The cerebellum is also divided
into two separate hemispheres
• These hemispheres are termed
the right hemisphere of the
cerebellum and the left
hemisphere of the cerebellum
• They are divided by a ridge
called the vermis
The Cerebellum
• The cerebellum has a large
number of specific nerve cells
• These Purkinje cells have
extensive dendrites that can
connect to up to 200,000
synapses
• This means that they can
coordinate large amounts of
information very quickly
Jobs of the Cerebellum
• The cerebellum coordinates
functions of balance and fine
muscle control
• Generally these jobs work together
• A good example would be a person
that has to jump to catch a fly ball
• They have to be able to use fine
motor control to be able to catch
the ball and their balance to land
safely
Jobs of the Cerebellum
• To do this the cerebellum must
communicate between the
spinal cord and the higher levels
of the brain to cause somatic,
visceral and higher level changes
• The information that is sent to
the cerebellum is often
coordinated or routed through
the pons before it makes it to
the Purkinje cells
Jobs of the Cerebellum
• It is possible for someone to
damage their cerebellum
• A damaged cerebellum happens
most often when there is trauma
to the back of the head, from blood
loss or from interference by drugs
• People who are drunk tend to have
trouble coordinating their motor
control
• This is because alcohol blocks
messages being sent it the
cerebellum
Video
• https://www.youtube.com/watc
h?v=Ny-tbJPsQgU
• Yup…
Jobs of the Cerebellum
• Ataxia is the result when the
cerebellum is not functioning
correctly
• It can be temporary (in the case of
alcohol) or permanent (in the case
of a stroke)
• Ataxia levels can range from having
alight abilities to balance and loss
of fine motor control
• Severe ataxia can cause the
inability to balance and use any
motor control
Video
• https://www.youtube.com/watc
h?v=mrt0Gq0zS4g
• Cerebellum Dissection