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SPEAKER: All right, ninja nerds.
So we've already covered the brain in another video.
Our intention in this video is just
to be able to give you guys another view
of the brain and some of the internal structures.
So let's go ahead and dive right into this.
So first off, if you remember from before,
we had this central sulcus here on the side.
And it's just this little groove right here,
running right there.
This guy right there is actually called the central sulcus.
So again, the central sulcus is this little groove
right here running all the way up right there.
And what's the purpose of it?
The central sulcus separates the frontal lobe
from the parietal lobe.
So if I come up the central sulcus
one more time, if I go right in front of this sulcus
to this gyrus right there-- because remember,
sulcus is this little divot.
And then a gyrus is this big, fat, lumpy thing right there,
right?
This gyrus in front of the central sulcus
is called the precentral gyrus.
It's also where the primary motor cortex is.
And if I follow the central sulcus because back up again
and I go to this fat gyrus that's right behind it,
that guy right there is called the postcentral gyrus.
And that's where the primary somatosensory cortex is.
All right?
And then if I were to go in front
of the primary motor here, which is where the precentral gyrus
is, I'd hit the premotor.
And then you come in front of that,
and you hit what's called the prefrontal cortex and so
on and so forth.
There's even called the eyelids, stuff like that.
But again, basic important thing right here
is central sulcus, precentral gyrus, postcentral gyrus.
The precentral gyrus is functionally
called the primary motor cortex.
The postcentral gyrus is functionally
called the primary somatosensory cortex.
OK?
Then if I were to continue to work my way back
to see where else does the parietal lobe--
where does that terminate, and where does it
go to another lobe?
So if I come over here, I'm going
to take this brain and kind of, like, open it up here.
Turn it around.
So if we look here, you'll see another sulcus right there.
That sulcus right there is actually
called the parietal occipital sulcus.
And the parietal occipital sulcus
is what separates the parietal lobe from the occipital lobe.
So back here is the occipital lobe.
I'll give you guys another view here in a second.
Just let me repeat that one more time again.
This is the parietal occipital sulcus.
And the parietal occipital sulcus
is what separates the parietal lobe, which
begins right after the central sulcus,
all the way up to this sulcus.
And it separates the parietal lobe, again,
from the occipital lobe.
All right, guys, so if we look back here,
we have the occipital lobe back there.
Again, and what separates the occipital lobe
from the parietal lobe is the parietal occipital sulcus.
Again, this is the occipital lobe.
In the occipital lobe, there is a specific cortex
that's actually called the primary visual cortex.
And so that's where, you know, the actual signal
transduction that comes from our retina that portrays basically
light, we can actually have the perception
of that light in this area to be able to perceive what we see--
you know, certain types of objects and shapes and colors
and so on and so forth.
So again, primary visual cortex is located
within the occipital lobe.
And then if I turn this to the right side,
our lateral side over here, we can see another sulcus.
And this sulcus is right here.
Actually, let me move rubber band, guys,
so we can see a little better.
If I move that rubber band right there and I move my finger
right-- or this little pointer here--
right through this area, right through that sulcus,
that sulcus right there is called the lateral sulcus.
Now, the lateral sulcus is the sulcus
that separates the temporal lobe, again,
from the parietal lobe and even a little bit
from the frontal lobe.
But this lateral sulcus runs right down here,
and it separates the temporal lobe
from the parietal lobe and even a little bit
from the frontal lobe.
So again, what is this lobe right here then?
I already said, this is the temporal lobe.
And the temporal lobe has a specific cortex in it,
which is called the primary auditory cortex.
And the primary auditory cortex is
going to be where we take specifically sound
and hearing from the cochlea in our inner ear
and we bring it to this area to be able to perceive and put
together different types of memories
to understand what we're hearing,
and we're able to perceive that hearing, right?
All right, so that's where the primary auditory cortex is.
Again, that's the temporal lobe.
There is another lobe we can't see.
And it's going to be deep to the temporal lobe,
and that's called the insula All right, so let's go ahead
and show you two more other areas that
are kind of important here.
And what I'm going to do is it's only
on the left side of the frontal lobe.
It's called the Broca's area.
So the Broca's area is just going
to be this little area over here on the left side
of the frontal lobe.
Again, it controls the muscles of speech production,
so being able to change the shape of our mouth
and other types of muscles that are basically assisting
with pronunciation and production of consonants
and so on and so forth.
But again, just controls the muscles of speech production.
There's another area back here.
It's kind of an overlapping area right around here.
That's called the word Wernicke's area.
Basically he just helps us to be able to understand what we're
hearing and put those words together
in a appropriate manner that when we speak it,
it makes sense.
OK?
So he does help with being able to play a role also
in speech production but also understanding speech.
All right, so that's the Wernicke's area.
Now what I'm going to do is we're actually
going to kind of take this guy here and turn it
forward here so I can show you another structure.
This whole thing up here is the cerebrum.
And the cerebrum-- and it's actually
derived from what's called the telencephalon, OK?
That's its scientific name.
But what I'm going to do is I'm going
to kind of separate these two cerebral hemispheres right
there.
And what happens is there's a fissure that
runs right between these two--
right between these two.
And that's called the longitudinal fissure.
Called the longitudinal fissure.
Why I mentioned that is there's what's
called dural sinuses that are veins
that run through this area, and we have to protect them.
So there's these things called dural septum, which are just
little septal partitions of dural matter
that dip down into this longitudinal fissure
and protect the dural sinuses.
And that dural septa that comes in here in the longitudinal
fissure is called the falx, F-A-L-X, cerebri.
So falx cerebri.
And again, it's right here in the longitudinal fissure.
All right, now I'm going to go ahead and turn this guy around
so we can tell you guys about another one.
So I'm going to come back here, back
where the occipital lobe was.
And if you remember, this was the occipital lobe, right?
Well, how do we know-- we know where the parietal lobe is.
You remember, it starts at the central sulcus,
and then it ends at the parietal occipital sulcus.
And that's where the occipital lobe begins,
at the parietal occipital sulcus.
Where does it end?
It ends right back here where there's
this little space in here right between the occipital lobe
and the cerebellum right there.
So in between here is what's called the transverse fissure.
And the transverse fissure is important
because there's another dural septa that
actually dips in that area.
And that right there is called the tentorium cerebelli.
Cerebelli, OK?
Tentorium cerebelli.
And it's just a dural matter partition or septa
that dips in that area.
OK?
Now what we're going to do is we're
going to go ahead deeper into the structures of the cerebrum
and take a look at that, OK?
All right, guys, so now what I'm going to do
is I'm going to show some other structures
underneath the cerebrum.
So deep in the cerebrum--
I just want to show you guys.
If you see all this white right here, this is all white matter.
And what white matter is, is it's just myelinated axons.
So it's myelinated axons.
And myelinated axons just means it
has this thing called myelin, which
is made up of fat and proteins.
It helps with basically nerve conduction,
the speed of nerve conduction.
But anyway, myelinated axons right here
is going to be the white matter.
All this pink stuff around the edges or the outsides of it,
this is all part of what's called our cerebral cortex.
And that's made of gray matter.
And gray matter is actually unmyelinated cell body.
So there's no myelin around the cell bodies.
OK?
So unmyelinated cell bodies is our gray matter, which
makes up the cerebral cortex.
You can think of that like as the thinking tissue.
So that's the part where they're the biomechanical centers,
and they basically--
they're the ones that control a lot of the thinking
or conscious thought.
This white matter, you could think of that
as like transmission tissue.
It's basically responsible for being able to transmit impulses
to and from certain areas.
OK?
So again, that shows you the cerebral cortex
and, again, shows you the white matter right there.
Now what we're going to do is we're
going to take a look at some other structures, which
is in the diencephalon and the ventricles.
All right, guys, I have the left cerebral hemisphere right now.
What I'm going to do is I'm going
to take this top piece off so we can take a deeper look
at some structures inside here.
All right, so if we take a look in here,
right now we're kind of in the lateral ventricle.
And ventricles are just basically cavities
within the actual brain and also within the brain stem.
And it contains what's called cerebral spinal fluid.
And we'll talk about that more in the neurophysiology stuff.
But if you look right here, sitting
in the bottom of the lateral ventricle down here,
this is actually-- if you remember from the other video,
it's called the hippocampus.
And the hippocampus is a limbic nuclei.
So it plays a role with memory and emotions
and so on and so forth.
So it does play a very, very important role
within, basically, memory.
If you look here, that's 190.
And if I come up here and I follow these white fibers
like 186--
if I follow it all the way from here,
all the way back, and then I come back up this way--
so again, all the way up here, following this guy,
and all the way back this way.
These fibers are very important.
They're called association fibers.
And association fibers are what allow
for the movement of impulses to go from front,
from in front of the cerebrum to the back of the cerebrum
or vice versa.
OK?
So again, these are association fibers,
and this is the hippocampus.
And then this whole cavity right here--
so like, for example, this is the inferior horn.
This is the posterior horn.
And then we'll see the anterior horn in a second.
That's all the lateral ventricle.
OK?
And again, you can see the white matter.
And then you can see the gray matter out there.
So the last structure here is going to be number 206,
and this is actually called the internal capsule.
And the internal capsule is actually specific fiber.
It's called a projection fiber.
And projection fibers are important for being
able to bring sensory information up
to the cerebral cortex, OK?
So they bring information up, all right?
But they do-- they can allow for information to go down also.
So they just basically offer movement to go up and down.
So association is back and forth, so back and front,
back and front.
And projection is up and down, up and down.
And we'll look at another one in a second called
the commissural fibers.
All right?
Now we're going to go ahead and turn it around and look
at some other structures, guys.
All right, so I just turned it around, guys.
So again, we're looking here at kind of like the other view.
I was on the back side.
Now we're looking over here on the front side.
So if you look right here, there's a nuclei right here.
It's a basal nuclei.
And basal nuclei just are important for being
able to dampen or smooth out certain motor movements.
He's one of them.
He's called the caudate nucleus.
So that's the caudate nucleus right there.
But this whole-- remember I told you there was another anterior
horn of that lateral ventricle.
So there's a little cavity here.
And this whole cavity right here is the lateral ventricle.
And if you look right here, this structure right there
is actually called the-- it's a choroid plexus, because there
is a choroid plexus, which is basically
made up of ependymal cells and pia mater.
And you're also going to have your capillaries in there,
and it's what helps to be able to make the cerebrospinal fluid
and circulate it.
So again, this is going to be the lateral ventricle,
this cavity here.
Imagine it, like, bathing this nucleus here.
Imagine it bathing this caudate nucleus.
And imagine this whole cavity filled
with cerebrospinal fluid, and that's
made by this thing called the choroid plexus.
And then you can see this fiber right there.
There's another white matter fiber,
and this is actually called the fornix.
And the fornix is a white fiber that actually-- it's
a tract, which is a bundle of axons
in the central nervous system that
connects multiple limbic nuclei together.
So again, this structure right here,
all the way from here, all the way from here,
this is called the fornix.
And the fornix is basically what helps
to be able to connect multiple limbic nuclei together.
So again, last time, lateral ventricle,
caudate nucleus, choroid plexus of the lateral ventricle,
and the fornix.
All right, so now we're going to go ahead and look
at some of these other structures in the diencephalon.
All right, guys, so this is right
here is the corpus callosum.
And the corpus callosum number 145 here,
this is actually going to be made up of what's
called commissural fibers.
And commissural fibers are just, again,
myelinated axons that allow for transmission of impulses
from left cerebral hemisphere to right
or from right cerebral hemisphere
to left cerebral hemisphere.
So it's very important for that connection.
It's also an area that's commonly
damaged during concussions.
And it's actually been found that women
have more commissural fibers than men do,
which allows for them to be able to have a little bit better--
be better at multitasking and stuff like that.
And it also plays a role in epilepsy and stuff like that,
but we're not going to get into that.
So again, corpus callosum there.
If you look here, there's a membrane 146.
So this thin membrane here is called the septum pellucidum.
And underneath the septum pellucidum
is that lateral ventricle that I was showing you guys before.
So underneath this septum pellucidum
is the lateral ventricle.
OK?
So it's just a thin membrane that separates the two
lateral ventricles.
Because, again, we have a lateral ventricle
in one cerebral hemisphere.
Let's say the right one.
And we'll also have a lateral ventricle
in the left cerebral hemisphere.
And the structure separating them, this membrane,
is the septum pellucidum.
If you guys look at the ventricle model we have,
you'll also see a better way of looking at that also.
All right, let's come back here again.
148 here, this is the fornix.
And again, that was that fiber tract
that connects a lot of the limbic nuclei together.
If I imagine I draw a whole circle--
say I do a whole circle all the way around here
or you imagine like an egg.
An egg is kind of like oval-shaped, right?
So this whole thing right here is the thalamus.
So this whole egg structure here with a whole bunch of nuclei
is the thalamus.
And the thalamus is actually the relay station
for a lot of sensory information going up into the cerebrum,
because he has tons of nuclei that regulate that activity.
Then if you look there, that little brown structure right
there, that's called the intermediate mass.
And it basically is like an interthalamic adhesion
between the two thalami, because you
have a thalamus in your right cerebral hemisphere,
and you have a thalamus in your left cerebral hemisphere.
So you have two of them.
If you actually imagine here--
imagine this being an eye, like a bird's eye.
OK?
So if you can imagine it, you can imagine the bird's eye,
which is kind of like the white of the eye
is like the thalamus.
And then the pupil right there is
where the intermediate mass is.
And if you imagine the bird's beak right there,
this right there, that bird's beak
is actually the hypothalamus.
So they can kind of say look at the bird's eye and a bird's
beak.
And again, the bird's eye is made up
of the thalamus and intermediate mass.
And the bird's beak is the hypothalamus.
If you look back here, you have what's
called the pineal gland, which is a part of the epithalamus.
Then you're also going to notice this little--
the hypothalamus has this little stalk
here on this side that connects to the pituitary gland that
would sit right underneath the optic chiasma.
Actually, this is-- if you look at 170 there, that's--
where the optic nerves cross, there's actually
called the optic chiasma.
So for example, this is the right cerebrum,
so this would be the right optic nerve here.
And it's getting ready-- some of its fibers
will cross over to the left side.
OK?
So that's kind of like the optic chiasma there.
And then this part right there is the infundibulum.
But if you look right there, that little,
like, ball there, that right there is
called the mammillary bodies.
And the mammillary bodies are also
important because they play a role within certain types
of olfactory pathways.
So they play a role in smell.
That's the mammillary bodies, and they're limbic nuclei.
So they play a role in recollective memory,
stuff like that.
OK, if you come over here, we're going
to see some other structures.
Now we're getting ready to start moving into the brainstem.
So as we get ready to move over here,
let's actually hit our brainstem.
So if you look right here, all this part right here,
this is all called the midbrain.
And they also call it the mesencephalon.
So it was derived from mesencephalon.
All this right here is our pons.
This is all our pons.
And the pons-- and this right here is the cerebellum.
They were actually derived from what's
called the metencephalon.
And then if we look here, all the way over here,
this is the medulla oblongata.
And the medulla oblongata was derived from what's
called the myelencephalon.
So again, I'll hit it one more time.
Mesencephalon.
And then you got your metencephalon, which is made up
of pons, and the cerebellum.
And then you have your myelencephalon,
which is the medulla oblongata.
All right?
OK.
Another thing here is-- oh, I also mentioned it a little bit
before.
I had mentioned that all this area right here
is the diencephalon.
The diencephalon is mainly made up
of three things, which we said thalamus, hypothalamus,
and then technically the epithalamus, which
consists of the pineal gland.
There's this little cavity right here
that also contains cerebrospinal fluid,
and this is called the third ventricle.
So the third ventricle would be a cavity right
in this vicinity right here.
So it actually gets drained from the lateral ventricle.
So here's our third ventricle.
The third ventricle actually drains
some of that actual fluid from the lateral ventricle.
Then there's another little tube right here running right here
through the midbrain.
So see that little tube right there?
That's actually called the cerebral aqueduct.
So the cerebral aqueduct drains the third ventricle,
and the third ventricle drains the lateral ventricle
via what's called the interventricular foramen.
So again, third ventricle here and then cerebral aqueduct
here.
Then the cerebral aqueduct moves into what's
called the fourth ventricle.
And then from the fourth ventricle,
the cerebrospinal fluid can go two ways.
It can go down through the central canal.
It will eventually go through the central canal
of the spinal cord or it can go out
through these two little holes called the foramen Luschka
and the foramen Magendie.
Or you can say foramen Magendie is the median apertures,
and the foramen Luschka is the lateral apertures.
OK?
So that's that part there.
OK.
Now, if we look here in the back of the midbrain,
we see these two little, like, balls there.
All right?
This top one right there is called the superior colliculi.
And basically what he helps you to do is being able to move--
it's like a reflexive movement of your head in response
to some type of visual stimulus.
For example, if I see Kate Upton walking by,
my head is going to move with response
to that visual stimulus.
Mm-mmm!
And then down here is the inferior colliculi.
The inferior colliculi actually controls reflexive head
movements or responds to auditory stimulus.
So for example, if Kate Upton's boyfriend yelled at me, hey,
what you doing looking at her, my head
would move that way too.
So that's an example of that right there.
OK, so superior colliculi, inferior colliculi there.
All right, so if I look here, guys,
there's another structure I want to show you.
It's 182 right there.
That structure right there is called the cerebral peduncles.
So it's like this stalk.
And again, these are projection fibers actually.
So if you remember, the cerebral peduncles,
these are projection fibers.
They're right around the midbrain.
And they carry sensory information up
into the cerebrum, OK?
So again, that's the cerebral peduncles right there.
All right, guys, so if we look here, I have 183 right there.
This is the pyramids.
This is the pyramids of the medulla oblongata.
That's where the descending motor fibers actually
decusse, or cross, right there.
OK?
So the pyramids is due to the decussation, or just crossing,
of the descending motor pathways.
All right, guys, so if we look over here
on the side of the medulla oblongata,
like, on this side of this, all this pink gummy
stuff, that's all the olives.
And the olives are actually broken up into two nuclei.
You've got their superior olivary nuclei
and inferior olivary nuclei.
And the superior, basically, they
play a role in basically the auditory pathways.
And the inferior olivary nuclei play
a role within proprioception and cerebellum motor function
and learning and stuff like that.
OK?
So again, olives play a role in proprioception,
and they play a role basically in hearing also.
All right?
So that's your olives.
Now what we're going to do, guys,
is we're going to basically go over the cerebellum now.
All right, guys, so if you look here, you can see all of this,
like, tree-like structure right there,
all this white, like, tree-like-looking thing.
All this white matter here is called the arbor vitae.
And the arbor vitae is just basically the white matter
of the cerebellum.
arbor vitae actually stands for, like, tree of life.
So again, all this white matter here is the arbor vitae.
And the outer gray matter on the actual edges
where you'll find, like, your Purkinje cells
and certain stuff like that, all the outer side
is the gray matter of the cerebellar cortex.
And again, that's just unmyelinated cell bodies.
Again, if you look here, in the back of the cerebellum
here, if you see all these little divots there,
it's actually called folia.
So the folia are basically like the folds of the cerebellum.
OK, so all these little lines right there
that you see forming these little folds,
that's called the folia.
All right, guys, if you look right here, right in
between the actual cerebellum, there's
actually this little worm-like structure between them.
It's actually called the vermis.
And in between the vermis, there's an actual dural septa,
like I said before, that actually runs in between there.
And that dural septa is actually called the falx cerebelli.
The falx cerebelli.
OK, again, so this structure right there between the two
cerebellum is the actual vermis.
And the dural septa that goes between the two
is actually called the falx cerebelli.
All right, so that pretty much covers the cerebellum.
Now what we're going to do is we're
going to move on to the cranial nerves.
So if we look right here, we're going to see cranial nerve one.
That's the olfactory nerve.
And again, remember that the olfactory nerve originates
in the nasal cavity through the olfactory epithelium,
and that actually picks up certain types of sensations
like smell from odorants in different types of chemicals
and carries that up through the cribriform
plate of the ethmoid bone and then up into--
specifically up into this olfactory bulb here
where there's glomeruli and mitral cells.
OK, so he's a sensory nerve.
Then right here, you're going to notice two optic nerves right
there.
So there's your left optic nerve.
There's your right optic nerve.
And then the point in which they cross
is called the optic chiasma.
OK?
And so the optic nerve is--
basically picks up sensations of vision.
So he picks up the vision stimulus
and then takes that into the actual cerebrum,
specifically to that primary visual cortex.
Then we're going to have to go and separate this guy
so we can look at some other structures here,
so we look at the midbrain a little bit deeper.
All right, guys, so if we look here,
we can see cranial nerve 3.
It actually comes out in between the interpeduncular fossa
right there at the midbrain.
That's called the oculomotor nerve, cranial nerve 3.
The oculomotor nerve actually runs
through the superior orbital fissure
and supplies a lot of the extraocular eye muscles.
I also didn't mention the hole that the optic nerve runs
through, but you can imagine it's the optic canal.
So again, oculomotor nerve runs through the superior orbital
fissure and supplies a lot of extraocular eye muscles.
Then if we come down here, we can see this little--
you see this little white thing right there, guys?
The little white piece of thing popping down there?
That's called the trochlear nerve.
So that's called trochlear nerve, or cranial nerve 4.
And the cranial nerve 4, or the trochlear nerve,
actually runs also through the superior orbital fissure
and supplies the--
it's called the superior oblique muscle.
It's just another extraocular eye muscle.
OK, so he plays a role in motor functioning.
All right, so here's the trochlear nerve again, right?
So that's cranial nerve 4.
And then if you look down here, we have these two nerves,
because they're paired, guys.
So we're going to see the trigeminal nerve here,
which is cranial nerve 5.
And you'll see the trigeminal nerve here,
which is, again, cranial nerve 5.
So the trigeminal nerve is a really big one,
and it actually splits into three branches.
And it actually runs through three holes.
It can run through the superior orbital fissure.
It can run through the foramen ovale and the foramen rotondum.
And the trigeminal nerve supplies the muscles
of mastication, and he also supplies
certain areas of the skin of the face to pick up sensations.
So he plays a role in muscle action, which is mastication,
chewing.
And he also picks up sensations on the face.
Interestingly, this is actually--
if this has what's called neuralgia,
trigeminal neuralgia, where there's
some certain type of nerve pain, this
can cause one of the most severe nerve pains actually known
to man.
It's actually called trigeminal neuralgia.
And it's extremely, extremely painful.
They actually call it the suicide . disease.
All right, then if we come down here to this structure
right there and that structure right there,
these are actually your cranial nerve 6, or the abducens nerve.
And he also runs through the superior orbital fissure.
And he supplies the lateral rectus.
And again, that's another extraocular eye muscle.
Then if we move out laterally over here,
we're going to have these two guys-- see this one right
there and this one over here.
That's actually called the facial nerve.
So that's cranial nerve 7.
So this one right there and this one right there, OK?
And the facial nerve has five branches.
But he can run through the stylomastoid, foramen.
And he also can run through the internal acoustic meatus.
But basically he supplies the muscles of facial expression,
a lot of glands within the-- like the lacrimal gland
and nasal glands and stuff like that.
So he plays a role in both--
and he also picks up sensations again from the face as well.
So he's actually a motor nerve and a sensory nerve.
OK?
So that's the facial nerve.
Then if we go over here to the edge,
that one right there over there and this one right there
on that edge, that is actually called the vestibulocochlear
nerve.
And the vestibulocochlear nerve, he also
runs through the internal acoustic meatus.
And he basically carries dynamic and static equilibrium and just
general sound and hearing.
And that's that guy.
Then if we come down here, there's
this little chunk right there, which
is the same chunk right there.
That's called the glossopharyngeal nerve,
which is cranial nerve 9.
And he actually runs through the jugular foramen,
and he supplies the tongue.
He supplies certain muscles of the pharynx.
He also can act as-- he can pick up sensations
from the baroreceptors.
So he plays a lot of roles in different sensory and motor
functions as well.
OK?
Below him is the vagus nerve.
So this one right there and this one right there.
That's cranial nerve 10.
So again, vagus nerve right there and right there.
He is the main parasympathetic nerve, OK?
He carries about 90% of the parasympathetic flow.
And he also runs through the jugular foramen,
and he supplies many, many different organs
from the heart to the lungs to the GI tract
to the urogenital tract, so on and so forth.
So again, that's your vagus nerve.
So if you look down here, guys, you'll
see this nerve right here and over here.
It's cranial nerve 11, which is called the accessory nerve.
Now, the accessory nerve has two parts.
One of them actually is on the cervical part
of the spinal cord and one on this medulla
here, like the medullary branch.
And what happens is the cervical branch of the accessory nerve
comes up through the foramen magnum
and merges with this branch off the medulla.
And as a collection, they run through the jugular foramen.
And they go and supply the trapezius muscle
and the sternocleidomastoid, which
are, again, those somatic muscles or skeletal muscle.
All right, so that's the accessory nerve.
So he's mainly a motor nerve.
And then the last one right here is this guy right there,
which is the same as this guy right there.
And that's cranial nerve 12, which is the hypoglossal nerve.
And the hypoglossal nerve actually
runs through what's called the hypoglossal canal
and supplies some of the extrinsic muscles
of the tongue.
OK?
So he's mainly a motor nerve.
All right, guys, so that pretty much
covers all the cranial nerves.
I hope this video helped, guys.
And see you, ninja nerds.