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now let's take a look at each of these
lobes to appreciate more fully the
functions that are associated with them
as well as the various of subdivisions
of each lobe and we can also explore as
we move through each lobe what might
happen if there's a lesion within a
specific area of a lope so here we're
looking at the primary motor cortex this
is shown right in through here in green
the primary motor cortex is associated
with the gyrus that's immediately
anterior to the central sulcus and this
is the precentral gyrus we have the
famous homunculus associated with the
primary motor cortex and the little man
the homunculus demonstrates the density
of upper motor neurons that are going to
control the musculature of various
regions of the body so we see a large
area here mapped out for the face
because a large number of motor neurons
upper motor neurons are gonna control
the muscles of the face we also have a
large area here mapped out for the hand
and again a large number of motor
neurons are gonna control the fine
delicate movements that are associated
with this part of our anatomy this
homunculus does extend over the top of
the cerebral cortex over the top of s
precentral gyrus and continues on the
medial aspect will see that continuation
on the next slide an important aspect
about motor control is that of the motor
neurons on one side here we're looking
at the left precentral gyrus they're
going to control the contralateral
muscles those that lie then on the right
in this case what might happen if
there's a lesion within the precentral
gyrus that will cause contralateral
paralysis or paresis and because you are
damaging and destroying the upper motor
neurons you may very well see a Babinski
response depending on the location of
the lesion so if the lesion is in this
area specifically you would have
contralateral paralysis or paresis of
the other hand for example if we
continue our view here on the medial
aspect of the precentral gyrus and again
that's shown in green we can see the
buttocks lie here on the superior aspect
the precentral gyrus medially and then
you can start to see the lower
extremities continue distally so that
the feet are approaching the cingulate
gyrus that's along here and so if the
stroke is in this area and you have a
lesion in this area and you're unable to
have upper motor neuron control of the
distal extremity of the lower extremity
then that's when you can see a Babinski
response as well as the contralateral
paralysis or Police's of that associated
anatomy another area of interest that I
want you to understand is that in the
premotor cortex the premotor cortex lies
anterior to the primary motor cortex and
we see it's a small area here but it's
essential in the programming of motor
events and so this programming will then
cause these neurons that reside in this
territory to activate prior to the
primary motor neurons that are within
the precentral gyrus a lesion of the
premotor cortex is associated with
apraxia apraxia is a motor speech
disorder this can be associate
with other lesions in the frontal lobe
our next area the frontal lobe is that
of the Supplemental motor cortex we see
it identified again anterior to the
precentral gyrus and it's involved in
the planning of complex up motor
movements a lesion of this cortical area
can cause a prac SIA as well another
area within the frontal lobe is the
frontal visual field cortex this area
right in through here it's even a bit
more anterior to the other areas that we
were describing that I was describing
for you it's involved in the
coordination of voluntary movements a
lesion of this small area can result or
real result in paralysis of conjugate
gaze to the opposite side and this is
discussed in another presentation
what conjugate gaze is and how that
circuitry works another important area
within the frontal lobe is this area in
blue this is Broca's area shown right in
through here this is the area of the
frontal lobe that's involved in word
production or motor speech a lesion here
results in expressive aphasia or
nonfluent aphasia
lastly within the frontal lobe I want
you to understand the prefrontal cortex
and we see that area here this is the
area of the cerebrum that takes some
degree of maturation to become fully
functional this is involved in executive
functioning and one of the the functions
under this heading would be that or
problem solving it's also involved in
making day-to-day multiple judgments
many times we make very very good
judgments or decisions and these
judgments as we mature tend to make us
make the right choice or the right
decision and another aspect of executive
functioning is that this is the area
that allows us to plan it also drives
behavior and emotions it's not the only
area but behavior and emotions are
modulated by the prefrontal cortex and
then an area the prefrontal cortex is
involved in olfaction the olfactory
pathway
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