today we're going to talk about the gross anatomy of the nervous system specifically the central
nervous system and the gross anatomy is the things are the things that you can just see
with your naked eye and so the central nervous system consists of the brain and the spinal cord
and there are some subdivisions within the brain itself we have our brainstem and our
cerebellum by convention the dorsal aspect of the central nervous system in the spinal cord
is the back think of yourself as a dolphin if you had a dorsal fin it would be coming out of
your back and that's the dorsal side and so the opposite of dorsal is ventral and that's your
tummy side and so that is the convention that we think about when we're thinking about the
central nervous system especially the spinal cord this is a section of a brain this well
actually this is a whole brain and this is the anterior or frontal Pole of the brain this is
the posterior or caudal pole caudal meaning tail and so if your brain had a tail it'd be on this
end and again the brain as you'll note maybe it's obvious from this this is the brainstem
leading into the spinal cord and you can see how this is at an almost a right angle with the rest
of the brain so what was dorsal here in the spinal cord is now up and what was ventral is now down so
the dorsal part of the brain is the is the top towards the crown of your head and the ventral
part of your brain is the part more towards the base of your skull so important landmarks that
you can see within the brain just right on the side really grossly things that were described
very early on are things like the lateral fissure which runs right here let me draw that in for you
lateral fissure the lateral fissure separates your frontal lobe from your temporal lobe
another important landmark that we can see here is called the central sulcus and it runs here
this is hard to do but I'm working on it there we go there's the central sulcus just anterior or in
front of the central sulcus is the pre central gyrus and just behind it or posterior to it is
the post central gyrus these two gyri are very important when we're talking about your primary
motor systems and your primary sensory systems in neurons that actually control movement live
right in this gyrus and the neurons that are responsible for your body map on your brain so
knowing exactly where that's mosquito bits you live right here in this post central gyrus the
other areas of the brain that you can see are the parietal lobe here and pull our most cuddly is the
occipital lobe okay there's not a real clear landmark between parietal and occipital on the
lateral side of the brain but there's a very clear landmark on the medial surface and I'll
show you that in a minute we can also still see our cerebellum and our brainstem as you'll note
on this lateral surface of the brain it's thrown into a bunch of folds the bumps are called gyri
and the folds in between them are called sulci the reason your brain has this appearance is
basically your brain is too big for your head and the only way we can fit your brain inside
your head was to fold it up and so this gives us this appearance of all of these folds and bumps
again we have this central sulcus here well here and our lateral fissure here we also have another
landmark that you can see here which is called the pre occipital notch and this is a boundary
between our temporal and our occipital lobes so the lateral fissure central sulcus pre occipital
knotch are all important landmarks on the lateral surface of the brain so as you know your brain
has two hemispheres a right and a left they're separated by a structure right down the middle
called the superior longitudinal sulcus also known as the longitudinal fissure and it runs right here
sorry that's a little bit off that you get the idea it's right in this zone and this
is the division then between your left and your right hemispheres your brain is divided into six
functional lobes the frontal lobe the temporal lobe and then just posterior to that central
sulcus is our parietal lobe and all the way in the back is our occipital lobe we have another
lobe that's buried if you look here at the lateral sulcus or lateral fissure if we pride that open
and removed some of this brain you'd see that there's even more brain deep to this structure
this buried lobe or Island lobe is referred to as the insula if we cut the brain in half and
look at the medial surface so this is the medial surface of the left hemisphere again we can see
our frontal lobe in our parietal lobe we can see our occipital lobe here's the cerebellum
here's the brain stem and just peeking out from underneath from the opposite side is our temporal
lobe right here the paracentral lobule is this section of brain up here where our pre and post
central gyrus come over from over the lateral surface onto the medial aspect of the brain the
parietal occipital sulcus here this very deep groove here is that clear landmark I referred
to earlier that separates our parietal and our occipital lobes some other important instructions
we can see is this big fiber tract here this is the corpus callosum and this large white
matter fiber tract is literally how your right ken knows what your left hand is doing this fiber band
connects all of the neurons from one hemisphere to the other another important part of the brain is
the diencephalon and when we talk about autonomic sand when we talk about sensory systems so it's
just kind of lump here in the middle this is gray matter that's deep within the brain it's old it's
very old it's so old that it doesn't have any layers and it's not part of the cortex but it's
kind of continuous with your brainstem you can also see the brainstem here and the cerebellum so
again the lobes that you can see from the medial surface of the brain are the frontal the parietal
and the occipital one other lobe is a lobe that is more functional than structural in the sense
that it crosses the boundaries of our frontal parietal and temporal lobes in this section
of the brain we've removed the diencephalon we've removed the brainstem in the cerebellum
and what we can see here is the cingulate gyrus which runs right around the top of the corpus
callosum it's set off from the the rest of the cortex by this cingulate sulcus which I'll try
to trace here so it kind of goes around that way so this is the cingulate sulcus and then this is
the cingulate gyrus it continues the limbic lobe continues into the temporal lobe and we follow our
collateral sulcus around underneath the temporal lobe and it the the internal boundary of that is
our parahippocampal gyrus so the parahippocampal gyrus combined with the cingulate gyrus forms your
limbic lobe and as you can see this kind of makes a half circle almost a complete circle which in
Latin is a limbus hence we call it the limbic lobe so the functions of your lobes so we have
six lobes and they all have slightly different functions your frontal lobe is mainly concerned
with the executive functions it's where your personality is where your decision-making takes
place the parietal lobe precentral or the post central gyrus is your primary sensory
cortex and there's a lot of Association cortex in the parietal lobe as well the temporal lobe
is your primary auditory cortex that is quite literally where you hear you may have all kinds
of vibrations coming into the ear but you don't really hear them until those signals breached
your temporal cortex the same for the occipital cortex it's your primary visual cortex and you
may have perfectly working eyes but if somebody comes along and scoops out your occipital lobe
you can't see so primary visual cortex is in the occipital lobe the insula we pretty sure it has a
lot to do with pain processing and it receives a lot of input from the sensations associated
with your viscera ie your hollow organs and your intestines and your heart and things like that
the limbic system has a lot to do with emotion arousal just meaning like you're paying attention
to your environment you're aroused interested motivation your what motivates you to get up
and go and conduct the business of every day is part of your limbic system and memory the
hippocampus is just deep to that parahippocampal gyrus and it has a primary function in memory
in summary what I really want you to remember from this particular lecture
are how many lobes and what are their names what are the landmarks the gyri or the salsa
or what other landmarks did I mention that separate these lobes so you can tell where
one starts and the other stops and then what are the functions associated with each of these lobes
if you understand all of the answers to these questions and you'll do very well on the quiz