Welcome to this presentation on the cerebellum. First, what I want you to understand is the functions
that relate to the cerebellum. We see the cerebellum in the image right in through here.
One of the primary functions of the cerebellum is to modify motor output to ensure that it is smooth
and moving in the right direction. It’s also involved in the maintenance of our balance and posture.
It helps to coordinate our voluntary movements. It’s involved also in motor learning or motor skill learning.
How to ride a bicycle, how to tie shoes are simple examples of motor learning. It’s also involved in
cognitive functions. Next, I want you to understand the fact that the cerebellum is divided into lobes.
We have a colored view of three lobes of the cerebellum. This is a sagittal view. The first lobe to identify
is the anterior lobe. It’s identified by the number one in the light green area. The posterior lobe is
the larger of the three lobes in this view and you can see it in the pinkish-red area. Then the third is much
smaller in contrast to the larger anterior and posterior lobes. That’s identified here in the orange area.
This is referred to as the flocculonodular lobe. Here is another view. This is an anterior view of the lobes.
Here is the anterior lobe in through here and on the opposite side. The flocculonodular lobes are these
extensions that we see here where it’s labeled. This is the opposite flocculonodular lobe over here.
The large posterior lobes are shown here and over here. Then a division between the lobes in the midline
is this structure referred to as the vermis and that extends here as well. The cerebellum can also be
divided into hemispheres. We’re going to use that same anterior view to identify the various
hemispheres of the cerebellum. There are three. The first is the vermis which is located right in through here.
This is involved in controlling the axial and proximal limb musculature. If there’s a lesion in this area,
it can result in ataxia of the trunk, those axial musculature. Patients will sway with their eyes open
due to the proximal limb musculature inhibition. A primary cause here of damage to the vermis is in
chronic alcoholics. They develop a nutritional deficiency of thiamine. As a result, there can be degeneration
of the superior aspect of the vermis. As a result of that degeneration, you’re losing your motor output
because you lose your Purkinje cell population or density here. The intermediate hemisphere is just lateral
to the vermal hemisphere. This is also termed the paravermis. It’s going to control distal musculature.
If there’s a lesion of this area, then you’ll have an inhibition of your distal musculature control.
The largest hemisphere is the lateral hemisphere. We see it running between these two green lines.
This is involved in motor planning. Symptoms of lesions usually include a lesion to the intermediate
hemisphere as well. This could be a stroke, loss of blood supply, or it could be a tumor impacting these areas
or hemispheres of the cerebellum. But the symptoms of a lesion would include ataxia of the extremities.
These individuals would exhibit an intention tremor. So as they move their upper limb, for example,
there can be tremor associated with that intentional movement. Nystagmus is another symptom;
dysmetria, an inability to judge the distance between your hand and the object that you want to pick up,
for example; decreased muscle tone, hypotonia; and lastly, deep tendon reflexes are weak.