in this demonstration I'd like to give you the opportunity to see a whole brain in
three dimensions in the lectures your see images of the brain but then this one in
this demonstration I hope to kind of rotate it around so you can see it's three dimensionality
so this is a whole plastinated brain this is the anterior Pole the posterior Pole and
then one of the main reasons you know that is because you can see the cerebellum back
here in the back some of the landmarks that we've talked about in the lecture include
the precentral gyrus which is here and the post central gyrus which is here you know the being
the main to visit the the main thing that divides the two gyri is this central sulcus
the central sulcus is a major landmark and it's really important because this
demonstrates the effective half of your brain the part where you think and plan and the sensory have
our preceptive part of your brain which is the posterior half so the central sulcus starts at the
top here along the superior longitudinal fissure or superior sagittal sinus you'll hear both names
and it goes all the way down to the lateral sulcus which is here and the lateral sulcus separates
your temporal lobe from your frontal lobe and your parietal lobe now the central the central
sulcus also separates then your frontal lobe from your parietal lobe so these are the three
lobes that you can see very easily on the lateral surface of the brain frontal parietal and temporal
you can also see your occipital lobe which is way back here in the back and we don't have a
real solid landmark for distinguishing a border between the parietal lobe and the occipital lobe
we kind of draw an imaginary line that kind of leads from the extension of the lateral fissure
kind of down toward this region in here there's a very clear landmark on the medial surface of
the brain that I'll show you in a minute so here's the lateral surface frontal parietal
occipital temporal lateral fissure and central sulcus precentral gyrus post central gyrus the
other two things I want you to remember from the lecture that are important about that precentral
gyrus is as your primary motor cortex so you think about moving up here you actually start
moving here these are the neurons that talk to the ones in your brainstem and spinal cord which
initiate voluntary movement this post central gyrus is your primary somatosensory cortex
and that is where any kind of sensation from your periphery so where that mosquito bit you you know
exactly where it is because that those neurons project to this sulcus or this gyrus here okay
so looking at the brain we can rotate it here you see it from the front this side does not
have any arachnoid remaining it's all been peeled away so you can just see the reason it's nice and
smooth is because the pia is still attached on this side on the right hemisphere we still have
the arachnoid attached to this side of the brain and that's why it looks kinda more opaque there
looks like there's a kind of a filmy layer on top and that's the result of the arachnoid being
collapsed and kind of a thicker layer over the surface of the brain so the the landmarks are a
little harder to see on this side you can still see the lateral fissure but it's really hard to
distinguish that central sulcus but you still know that this is going to be the frontal lobe
parietal lobe occipital lobe and temporal lobe from the back you can clearly see the cerebellum
the cerebellum means little brain and you've got a ton of neurons back here we'll talk about that
in the cerebellum and motor systems lecture but they're almost as many neurons in here as there
are in the whole rest of the brain underneath let me flip so that you're looking at it kind of right
the touch side up so here again is our frontal lobe and here our temporal lobes and here's our
brainstem you can clearly see the pons and the medulla and you can then also the part of the
cerebellum you can see also we have one big blood vessel here this is going to be the basal basilar
artery and part of the vertebral it's just one of those horrible facts of life that on plastinated
brains the vasculature doesn't survive very long it's a kind of fragile and it often will fall off
from years of years of students using the brains but we still have a basilar and a vertebral you
can also see our optic nerves here and here coming together to form the optic chiasm and
you can see just a little bit of the olfactory nerves the olfactory bulb is missing on this
side you can see part of it here and I'll have better examples of this in future demos I just
basically wanted you to get familiar with the the underside of the brain this is the the side of the
brain that fits on the skull base and of course the top is what is seated in the cranial vault
two more lobes that I want to talk about that you can't really see from a whole intact brain
so I'm going to set this to the side and pull up this way so just deep to the lateral fissure
let's see let's get the right side so lateral fissure is here if you open that up you would
see just deep - it is our insular lobe and that's this grey matter here this is another example
of the fact that your brain is too big for your body for your head um that's clear because it's
thrown into all of these folds the gyri are the big lumps and the sulci are the folds and it's
folded because your brains too big for your head so you have to fold it up to fit it in there and
this is further evidence of that that you've even fold the folds so that you have the insula buried
underneath the rest of the cortex on the medial surface of the brain if you cut the brain in half
if you just whack right through there with a big knife it's called a brain knife you end up with
this view okay and again you can see the frontal lobe here and the parietal lobe and here's that
big landmark I wanted to point out the occipital parietal occipital sulcus which is right here and
that's clearly separates the parietal lobe I'm sorry the parietal lobe here from the occipital
lobe here you can see your brainstem you can see the cerebellum and you can see this also this big
band of fibers here which is really important this is your corpus callosum we'll talk more about this
in the lecture about the white matter that in the in the cortex but the bottom line is that
the corpus callosum attaches your hemispheres together it is literally how your right hand
knows what your left hand is doing okay this area is a very special area of the brain called the
diencephalon and the diencephalon includes the thalamus and the hypothalamus and those are very
important areas for the thalamus is a sensory gap gateway all of your sensations come through
the thalamus before they go up to the cortex before they go up to that post central gyrus
and the diencephalon sorry the hypothalamus is a very important regulatory center when it comes to
metabolism and the chronology and basic drives survival drives like to get a drink of water or
to eat again we can see our brainstem this is the pons this is the midbrain which you can't
see from the underneath but you can see it here and our medulla you can see just the edge of the
temporal lobe here so the other lobe I wanted to show you I showed you the insula can't see
it on this one got to go back to this one so oh I know what I wanted to say you can see into the
lateral ventricles we're going to talk about the ventricles in another demo but you can see that
you do have holes in your brain so and that's not important right now we'll talk more about
that in the next demo so corpus color so back to the other brain where we saw our insula if we
also look on the midline there's another structure called the limbic lobe and the limbic lobe crosses
the borders of the frontal and the parietal and the occipital almost the occipital not quite the
frontal and the parietal and the temporal and it it's not as anatomically lobe although it is it
does have some anatomical features it's more of a functional lobe and it follows this gyrus which is
called the cingulate gyrus and it goes right above it's right up on top of the corpus callosum which
is here so this cingulate gyrus comes all the way around so from the frontal lobe into the parietal
lobe and then it dips down and we also include this region which is called the parahippocampal
gyrus to here so we can it forms this semicircle or limbus limbus is I don't know Greek or Latin
for circle and so if this limbic lobe here is defined by the paris impaired hippocampal gyrus
the collateral sulcus the cingulate gyrus here those are the major landmarks that you can see
on most brains they're going to vary a little bit from brain to brain but in general they're
pretty consistent here's the lateral sulcus again here's our central sulcus or our lateral fissure
central sulcus on this one again here's our lateral fissure and it's really hard to see
the central sulcus on this brain alright I would hazard a guess and say it's probably this one
but you can see that this one's not as clear as some of the others so as you move forward in your
neuroanatomical education you have to realize that there's going to be variability and that
concludes my demonstration of all of the things you can see grossly on the outside of the brain