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Neurology | Pons Anatomy & Function — Transcript

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0:00All
0:14right, ninjers. In this video, we are
0:15going to talk about the neuroanatomy of
0:17the pond. So, let's go ahead and get
0:18started. All right, engineers. So, what
0:20we're going to do is we're going to look
0:21at the kind of internal structures of
0:23the ponds and then we'll go into their
0:24function in more detail as we kind of
0:26move towards the right of the
0:27whiteboard. First thing we need to know
0:29is we have to look at two sections or
0:31cross-sections or transverse sections of
0:33the pawns. Okay, one is going to be here
0:36on the left is going to be at the
0:37trigeminal nerve level. Okay,
0:39particularly at the level of the
0:40trigeminal motor nucleus. The one on the
0:43right is going to be at the level of the
0:45facial nerve or the abdusins nerve.
0:48Okay, let me give you guys a little
0:50orientation on that. So if I draw like a
0:53little mini diagram here, here's my
0:55cerebrum, right? midbrain pawns medulla
1:00and then I have my spinal cord here is
1:02going to be the cerebellum right the
1:05pawns you have a particular level here
1:09right at this level we're going to have
1:11right here is going to be at the level
1:13of the trigeminal motor nucleus okay so
1:15out out from this you'll have the
1:17trigeminal nerve the motor nerve and
1:20again you'll have a sensory nucleus
1:21there as well at the lower level just a
1:25little bit lower closer to that pawns
1:27medulla junction. So again, if I were to
1:29kind of draw like a line there, that's
1:31kind of right around the area between
1:32the pawns and the medulla just below it.
1:36Right around that level, we're going to
1:37have the level of the facial nerve,
1:40and we're going to have this at the
1:42level of the abduins nerve. Okay? So,
1:47we're going to take two sections. One is
1:49going to be here, and that's going to be
1:50on the left. That's the level of the
1:52trigeminal. and we're going to take
1:53another section and that's going to be
1:55at the level on the right which is gonna
1:56be at the level of the facial and
1:57abducence nerve. Okay, so let's go ahead
1:59and focus here at the level of the
2:00trigeminal nerve. All right, so let's go
2:03ahead and take a look here at this
2:04cross-section at the level of that
2:06trigeminal nucleus motor and sensory
2:08nucleus here. Okay, now what I want you
2:11to remember is that there's a vententral
2:13portion here. So when we're looking at
2:14this, giving you guys some orientation,
2:16this side here is the vententral. This
2:19side here is the dorsal. Okay? Or
2:21another way that we can say it is
2:22anterior and posterior. Okay. Now
2:26another thing is sometimes questions
2:28might come up where they might say okay
2:31what is the vententral portion of the
2:35pawns called? In other words here's your
2:37trapezoid body right? We'll get into all
2:39these structures in a second but this
2:40blue kind of like uh diamond thing here
2:43is going to be the trapezoid body.
2:45Anything that is anterior to the
2:47trapezoid body. So from here all the way
2:50till here this is the base or the basil
2:54part of the pawns. Okay. Anything from
2:58this part of the trapezoid body all the
3:01way back here to the back part most
3:03dorsal point is the tegmentum of the
3:07pawns. Okay. So again this part basler
3:10part of the pawns. This part all here
3:13tegmentum of the pawns. Okay. So let's
3:17talk about stuff in the vententral or
3:19basil part of the ponds first. Then
3:21we'll get into all the structures in
3:23this dorsal or tegmental part of the
3:25ponds next. Okay, first things first. We
3:28have all these little orange dots within
3:30the basil part of the ponds. What are
3:32these little uh these little orange
3:33dots? These little orange dots here that
3:36we're going to talk about. We're going
3:37to have like a key so that this diagram
3:39doesn't get too crazy here. These little
3:41orange dots are called your pontene
3:44nuclei. Okay, so these are called your
3:46pontene
3:49nuclei. And again, we'll talk about
3:50their function in a little bit, but one
3:53of the big things I want you guys to
3:55remember for this in kind of that
3:56one-word sentence is that the pontine
3:58nuclei, what happens is you have
3:59descending motor fibers coming from the
4:01cerebral cortex that some of them will
4:04synapse on these pontene nuclei. Then
4:08when they synapse on these cell bodies
4:11or these pontine nuclei, some of the
4:13fibers from the pontine nuclei on the
4:15left side of the pawns will cross over
4:19to the opposite or contraateral
4:21cerebellum. The ones on the right side
4:24will cross over and send their axons
4:27from the right side of this pawns to the
4:30contrlateral or left cerebellum. How do
4:32they do that? You see these black fibers
4:35here? If I were to kind of imagine here,
4:37here's going to be the syninnapse at
4:39this point. And from here, this guy is
4:41going to go this way. He's going to make
4:44his way across these. These are your
4:47panto cerebellar fibers, right? So, what
4:50are these fibers here called? These are
4:52your panto
4:55cereabellar
4:58fibers. And again they are going from
5:01one side of these pontine nuclei to the
5:03contrlateral cerebellum.
5:06When they go towards the contrlateral
5:08cerebellum, how do they communicate with
5:10the contrlateral cerebellum? Do you guys
5:12remember? They're going to make their
5:14way. So for example, it would come down
5:16here to this guy. He would cross over
5:18this way, continue to keep crossing,
5:22continue, and then move into this little
5:24black structure here. What is this
5:26called?
5:27These are called your middle
5:31cerebellar
5:34podunks.
5:38Okay, so you have middle cerebellar
5:39pedunals. And again, we already talked
5:41about these when we talked about the
5:42midbrain. Those are the superior
5:44cerebellar podunkles. If we're at the
5:46pond, it's the middle cerebellar
5:47podunks. And if we're at the level of
5:49the medulla, it's the inferior
5:50cerebellar pedunless. So again what I
5:52want you to remember in the basler part
5:54pontene nuclei receive their information
5:57coming from descending motor pathways
5:59from the cortex to the pontine nuclei.
6:02When they synapse on the pontine nuclei
6:05these pontine nuclei will send their
6:07axons to the contrlateral cerebellum via
6:10the pontto cereabellar fibers. These
6:14panto cerebellar fibers will then move
6:16into the middle cerebral podunks which
6:18will connect them to the contrlateral
6:20cerebellum. That's it. That should make
6:23perfect sense now. Okay. All right. We
6:25covered the basler part. We're almost
6:27home. Let's move on to the next part. If
6:30we covered the basler part, let's go
6:32into this tegmental part. What did we
6:33say the tegmental part has right here at
6:35this portion? What do we say that was
6:37before? That's the trapezoid body. Okay.
6:40So this is the
6:42trapezoid
6:45body and we'll talk about what that is
6:47in more detail later. What I want you to
6:49know and that one kind of line sentence
6:52is the trapezoid body is where the
6:56hearing the cclear fibers. Okay? So the
7:00fibers that are coming from the cclear
7:02nuclei they cross and they move up into
7:06what's called the lateral liiniscus. We
7:09talked about that in the midbrain. Okay.
7:11So the trapezoid body is going to be
7:13these kind of like crossing of the
7:16cclear fibers or we call them the
7:18acoustic stria. We'll get into more
7:20detail on that. I just want you to know
7:21that this is basically where the
7:22crossing of the auditory pathway is.
7:25Okay. Now let's go a little bit farther
7:28back. We go a little bit more dorsal
7:30into the tegmentum and we have these
7:32purple structures and we're going to
7:34cover them on one side but we're going
7:35to move from medial all the way out to
7:38lateral. Okay. So what are these
7:40structures as we go from medial all the
7:43way out to lateral. So this would be the
7:44most medial portion here
7:47and this will be the most lateral
7:49portion.
7:51The most medial is the medial
7:56lemoniscus.
8:00As you go a little bit more out, then
8:03you have the trigeminal
8:08liiniscus.
8:11As you move a little bit more out, you
8:14have the spinal lemonus.
8:20And as you move all the way out to the
8:22lateral part, you have the lateral
8:25lemoniscus.
8:28Okay, we talked about these in great
8:30detail in the midbrain video. Super
8:34quick little thing. Medial liminiscus
8:36carries
8:38sensory information from the dorsal
8:40column. Propriate reception, fine
8:42discriminative touch, vibrations.
8:45The trigeminal liiniscus is carrying
8:47touch, pain, temperature, propriary
8:48reception, pressure sensations from the
8:51face.
8:52The spinal liiscus is carrying pain,
8:55temperature, pressure, crude touch from
8:58the upper the uh from the neck all the
9:01way down. Okay. And then the last one is
9:04the lateral li meniscus. And again, what
9:05do we say would happen from here? Just
9:07to kind of put this in perspective,
9:08there's a little bit of these fibers
9:10here. Remember the trapezoid body? Some
9:12of these fibers will cross over and move
9:14into the lateral laminiscus. And we'll
9:16talk about where they come from. This
9:17will make more sense, but they'll come
9:19here into the lateral laminiscus. that
9:21son of a gun that's carrying hearing,
9:24okay? Sensory information from the inner
9:27ear, okay? Particularly from the cookia.
9:30All right, so let's move a little bit
9:31more back, but again, let's hit these
9:33kind of blue structures here. Then we'll
9:34work our way back to the midline. Okay,
9:36so we already hit medial liiniscus, we
9:38hit the trigeminal, we hit spinal, we
9:40hit lateral miniscus. What's these blue
9:42structures here on the outer parts? This
9:45blue kind of like structures here are
9:46actually ascending fibers. And these
9:49ascending fibers are a part of your
9:52vententral
9:55spino cereabellar
9:59spino cereabellar tract and that is an
10:03ascending tract. Okay? So it's carrying
10:06kind of these proprioceptive information
10:09which is position sense from your
10:10muscles, your tendons, your joints,
10:13right? It's going to be sending that
10:15information to the cerebellum and it
10:18actually will ascend up. It actually
10:20comes up through the medulla. It comes
10:22up through the ponds and it comes up all
10:25the way up to the midbrain and moves in
10:27via the superior cerebellar podunks into
10:30the cerebellum. Okay, so that's the next
10:33one. Let's move now into the middle
10:36here. We have these kind of these red
10:38tracks. These red tracks here are
10:41actually is a descending tract.
10:43This is actually the rubspinal tract.
10:46Okay, this is the rubro
10:50spinal tract.
10:53Remember this is a descending motor
10:55pathway to what? Flexor muscles. Okay,
10:58particularly of the upper extremities.
11:00Next one, the blue guy here.
11:03This blue guy here is actually the
11:06tetospinal tract. You guys remember that
11:09one? The teto
11:11spinal tract. That's going to be sending
11:13descending
11:15information, motor information from the
11:18tectum, which is primarily the superior
11:21caliculus and inferior caliculus down to
11:24the motor neurons that are going to play
11:26a role within movements of the head, the
11:29neck, and even the eyes in response to
11:32either a visual stimulus from the
11:34superior caliculus or an auditory
11:36stimulus from the inferior caliculus.
11:38Okay. All right. All right, let's move a
11:40little bit dorsal in the tegmental part
11:41of the ponds, right? So, we hit rub
11:43spinal, we hit teacto spinal. What's
11:45this bad son of a gun? This guy right
11:47here is your medial longitudinal
11:49faciculus, right? So, what is this guy
11:51here? If we come down here, just use our
11:53key here. This is the medial
11:56longitudinal
12:00faciculus.
12:02You guys remember what that son of a gun
12:04connects?
12:06Remember this is basically coming from
12:09the sixth nerve the abdusen's nerve
12:12crossing over and connecting the third
12:16and fourth nerve ocular motor and tlear
12:18nerve right so it's basically an kind of
12:21an ascending tract that connects what
12:25three cranial nerves third fourth six
12:28cranial nerves and it helps with
12:30basically conjugating our eye movements
12:32making sure that they're coordinated
12:34okay So that's the medial longitudinal
12:37faciculus. Okay, this actually very
12:39common important thing to remember
12:41because this can get damaged in patients
12:42with multiple sclerosis. We'll talk
12:45about that when we talk about multiple
12:46sclerosis, but it can lead to what's
12:47called inter nuclear abdomlasia whenever
12:50this can be damaged. Okay,
12:52last thing here that we're going to talk
12:53about then we'll kind of talk about
12:54these couple last structures here. Okay,
12:57you got this this red nucleus here and
13:00this green nucleus. Again, what do we
13:02say? We're at the level of the
13:04trigeminal nucleus, right? The
13:06trigeminal motor nucleus and the
13:08trigeminal sensory nucleus. Okay. So
13:12again, this red structure here is the
13:14trigeminal motor nucleus. The green one
13:17there is the trigeminal sensory nucleus.
13:20So let's come down here right that get
13:21rid of our key here. Right? So the red
13:23one is the motor nucleus
13:27of the trigeminal nerve of cranial nerve
13:32five.
13:34If you guys watched our videos on each
13:36individual cranial nerve, we go into a
13:39lot more detail on the trigeminal nerve
13:42and how this is basically supplying the
13:45structures of the first frenial arch.
13:47Does that sound familiar? These are part
13:49of your special visceral eerant fibers,
13:52right? And that's supplying
13:55those muscles of mastication. We'll talk
13:57about those in more detail later. The
13:58medial terragoids, lateral tragoids,
14:00massitor, temporales, all those bad
14:02boys. So again, that's what his
14:04responsibility is for. Okay. The green
14:07guy is actually going to be the sensory
14:10nucleus. Now, we're at the level of the
14:13pawns, right? So because we're at the
14:16level of the pawns, this sensory nucleus
14:19is actually referred to as the central
14:22or principal pontene nucleus of the
14:25trigeminal nerve. So again technically
14:27the sensory nucleus since we're at the
14:29level of the pawns particularly right at
14:31the level of the trigeminal motor
14:33nucleus this is called the central
14:37or principal
14:43pontene
14:45nucleus
14:48of cranial nerve five or the trigeminal
14:52nerve. Okay.
14:54So again, sensory nucleus, what is it
14:57picking up information from? It's
14:59picking up information, and we'll talk
15:00about this in more detail later.
15:02Basically, sensations from the face.
15:05Okay? And we'll get into more detail on
15:07that. And if you guys want to know all
15:08about all these different fibers and
15:10nerves related to the trigeminal nerve,
15:13go watch our video. We have a specific
15:15video on the trigeminal nerve. Okay? All
15:17right. So, that covers all the internal
15:20structures at this point of the
15:21tegmentum. Let's go a little bit farther
15:23back.
15:24Okay. What do we have next?
15:27All right. You see this guy here? Big
15:29fluid fil cavity. You know what this big
15:32fluid fil cavity is called? This big
15:34fluid fil cavity here is called the
15:37fourth
15:38ventricle. And the fourth ventricle is a
15:41fluid fil cavity filled with cerebral
15:44spinal fluid. And it's basically going
15:47to receive this fluid from the above
15:50cerebral aqueduct. So in the midbrain
15:52you have the cerebra aqueduct fluid
15:54drains down into the fourth ventricle.
15:56Then from the fourth ventricle we'll
15:58talk a little bit later it can actually
15:59move out through the median or lateral
16:02apertures or the fammen lushka or the
16:04fammeni or it can go down through the
16:07central canal into the spinal cord.
16:09Okay. Now in the back part here in the
16:14back part of the fourth ventricle in the
16:15back part of the pawns you have this
16:16kind of like structure here and this is
16:19called the superior medularary vellum.
16:22Okay. So they call this the superior
16:26medularary
16:29vellum. Okay. So again we have the
16:33superior medularary vellum and then just
16:35anterior to that you have this fourth
16:36ventricle.
16:39Last thing is you have a tiny piece a
16:42tiny little piece of the superior
16:44cerebellar podunks and the dorsal part
16:46of the pawns. A tiny little piece of
16:48that. So again remember what do we have
16:50back here in this most dorsal part? A
16:52tiny little piece of the superior
16:56cerebellar podunks. Okay, you'll see
16:59this a lot in books where they'll have
17:00this. Again, I want you to remember that
17:02the main connection
17:04between the superior cerebellar podunks
17:06is between the cerebellum and the
17:07midbrain. Middle is between the
17:09cerebellum and the ponds and inferior is
17:11between the cerebellum and the medulla.
17:12But again for a sense of anatomy there
17:15is superior cerebellar podungals a tiny
17:17little piece of them and this dorsal
17:19part of the pawns tegmentum. Okay. All
17:22right. That covers the cross-section at
17:23the level of the trigeminal motor and
17:25sensory nucleus. Let's now move on to
17:27the level of the facial and abducins.
17:29All right. So now we're going to take a
17:30look at the cross-section of the pawns.
17:31Right. But this is going to be at the
17:32level of the abducins and facial nerve.
17:35Okay. Sometimes people will just even
17:38say this is the level of the facial
17:39caliculus and I'll explain what that
17:41means in just a second. Okay. So again
17:43giving you guys some anatomical
17:44orientation. This is the vententral.
17:46This is the p posterior or dorsal
17:48portion. So again vententral anterior
17:50posterior dorsal portion. Again giving
17:53you guys those terms. This part here
17:55anterior to the trapezoid body all the
17:58way to the most vententral portion. This
17:59is the base or the basil part of the
18:02pawns. Anything from the trapezoid body
18:05all the way back here. This is the
18:08tegmentum of the pawns. Okay, a lot of
18:12this should be review. Okay, so we'll
18:14annotate. We won't write everything
18:15down. What is these guys going to be
18:18here in the the actual basler part? This
18:20is your pontine nuclei. I'm just going
18:23to put PN here, right? So PN pontine
18:25nuclei. What are these guys that are
18:27going to move in the contraateral
18:29direction? So again if if descending
18:31fibers are coming down from the cortex
18:33to the pontine nuclei these pontine
18:35nuclei are going to send fibers in the
18:36contrlateral direction. What are these
18:38called? Panto cereabellar fibers. These
18:42panto cereabellar fibers will move in
18:45towards the direction of the
18:47contrlateral cerebellum via the middle
18:51cerebellar podunks. And again, same
18:53thing. If I had descending fibers coming
18:55to this ponte nuclei, it's going to send
18:57its information via these panto
18:59cereabellar fibers to the contraateral
19:03cerebellum via what structure? We
19:06already hit it. It's the middle
19:08cerebellar podunks. Okay. Pontine nuclei
19:10pontine cere ponto cerebellar fibers.
19:13Middle cerebellar podunks pretty much
19:15make up the basler part. Work our way
19:18backwards into the tegmentum. We already
19:20hit this before. So this is your
19:21trapezoid body. All right. Some of these
19:24structures here after we go from the
19:25trapezoid body, we work our way back.
19:27Some of these structures would be the
19:28same here, right? So this purple guy in
19:30the medial portion is the medial
19:32lemoniscus.
19:34Work our way out. You would think, oh,
19:36that's the trigeminal liniscus because
19:37that was the one before. Not really.
19:39We'll talk about why in a second. What's
19:42the next one as you go a little bit more
19:44laterally? That is the spinal lemonus.
19:47And you guys might be wondering, well,
19:49isn't there supposed to be a lateral
19:50liin miniscus? Not yet. Remember, we're
19:53at a lower level. We're at the facial
19:56caliculus level. The lateral luminiscus
19:57hasn't formed. But if you guys remember
20:02what forms the lateral liniscus,
20:04remember fibers from the cclear nuclei
20:06will cross via the trapezoid body and
20:09come up as the lateral liiniscus. Klear
20:13nuclei from this side will cross over
20:15and become the lateral liiniscus. Okay,
20:19so we haven't formed the lateral
20:20liiniscus yet, but we have the medial
20:22liin miniscus and the spinal laminiscus.
20:25Okay, work our way out a little bit
20:27more. What was after the lateral
20:29liiniscus? Do you guys remember that was
20:31your vententral spino cereabellar tract?
20:35Again, that was carrying that
20:36proprioceptive information from, you
20:39know, again, your muscle tendons, your
20:41joints, uh your your your capsule within
20:44the ligaments, right? All of those
20:46different things. And then these are
20:48going to be coming up to the superior
20:50cerebellar podunks. All right, let's now
20:53work our way a little bit more back.
20:56Okay, let's hit these guys. And we'll
20:58come back to these in just a second. So,
20:59we're going to come here to this kind of
21:01maroon colored guys here. These maroon
21:04color guys, there's two parts of it,
21:06right? The ones that looks like the
21:08nuclei. This is going to be the spinal
21:12nucleus of the trigeminal nerve. Let's
21:15write that down. So this nucleus part.
21:18Okay, this guy here, this is your spinal
21:23nucleus
21:26of cranial nerve five or the trigeminal
21:29nerve. And we'll explain this in a
21:32little bit. The spinal nucleus extends
21:34from the lower part of the pawns all the
21:35way down into the medulla even a little
21:37bit into the portion of the spinal cord.
21:39Okay.
21:40The other one is going to be the
21:44trigeminal phalamic tract or part of the
21:49trigeminal liiniscus. So we're going to
21:51put here part of the trigeminal
21:55liiniscus. It just it we're having some
21:58fibers coming off from this spinal
22:00nucleus that will move as the trigeminal
22:03tract or the trigeminal liniscus that
22:05will move up into the upper level of the
22:07ponzo which we had in the previous
22:08section. Okay.
22:11All right. We covered that bad boy. Now
22:14we're going to talk about what else this
22:15thing does in just a second because
22:17you'll see that this is connected to
22:19something else. There's this long axon
22:20coming off. I'll explain in a second.
22:22Let's now move into this next component
22:25here. Okay, I want to circle something
22:28here. Okay,
22:31I'm going to circle all of this. I'm
22:33going to put like kind of a dotted line
22:34here.
22:37All of these nuclei that are surrounded
22:40by this dotted line are a part of the
22:43facial nerve. Okay? They're all
22:47connected through multiple different
22:49sensory and motor systems. If you guys
22:51want more detail on this, go watch it in
22:53our video on the facial nerve. What I'm
22:56going to do for right now is give you a
22:57little bit explanation on this. So, what
23:00I'm going to explain here is you have
23:01the facial nerve. It has multiple
23:03different sensory and motor fibers.
23:05We're going to go from the purple one
23:06and work our way and again talk about
23:08this uh maroon colored one last. Okay.
23:11So, the first thing that we have to talk
23:12about here, we have this purple guy.
23:16This purple nucleus,
23:18this purple nucleus with its axons that
23:21are going to be coming around, this is a
23:22part of the facial nerve. But this is
23:25going to be the motor nucleus
23:30of
23:31cranial nerve 7 or the facial nerve.
23:35Give you guys a little bit information
23:36about that. Remember the facial nerve,
23:38the motor nucleus, it supplies the
23:40muscles of facial expression. And again,
23:42if you guys remember had all those
23:44branches, right? So you have the uh
23:47temporal branch, you have the zygomatic
23:49branch, you have the buckle branch, you
23:51have the marginal mandibular branch, you
23:52have the cervical branch. It's supplying
23:54all those muscles of facial expression
23:56and even a little bit of the platisma.
23:58So if you guys want more detail on that,
24:00you guys go watch that. But again, this
24:01is the muscles that are going to be
24:03supplied by the facial nerve.
24:06Okay. Now because these muscles are
24:10actually a part of your fingial arch,
24:13these are actually going to be muscles
24:15that are coming from the second fingial
24:17arch. So these fibers we actually call
24:21special visceral eerant fibers just like
24:24those motor fibers coming from the
24:26trigeminal nerve. Those are supplying
24:28the first fangial arch. So those are
24:30going to be special visceral eerant
24:32fibers. Okay,
24:35the green one. Okay, the green nucleus
24:38is actually going to be a very special
24:40nucleus. This guy here is called the
24:43superior
24:46salvatory
24:49nucleus
24:52and this is going to be connected to the
24:54facial nerve as well. Now the superior
24:56salivatory nucleus this is going to have
24:59its axons its fibers and these are going
25:02to be parasympathetic fibers.
25:05parasympathetic fibers going to the
25:07lacrial glands, going to your paline
25:10glands, going to your salivary glands.
25:12So they play a role in lacrimmation,
25:14nasal secretions, and salivation.
25:17So these are parasympathetic
25:20nervous system fibers, but they're
25:22actually called general visceral eerant
25:26fibers of that facial nerve. Okay, go.
25:30Next one. The black nucleus here with
25:32its axons here. This is actually going
25:35to be a very special nucleus called the
25:38nucleus
25:41of tractus
25:44solitarius.
25:46Right? Is it cool to say that one? The
25:47nucleus of tractus solitarius. This guy
25:51here is actually going to be picking up
25:54sensory information from the anterior
25:57twothirds of the tongue. Taste. So that
26:01is actually a special kind of sensory
26:03system. Right? So these fibers are
26:05coming from the tongue anterior
26:07two-thirds of the tongue and they're
26:08picking up taste or gustation and
26:10they're coming back to the ponds. So
26:14these are special visceral aerant
26:18fibers. Okay. So so far we have muscles,
26:22we have salivation, lacrimmation and
26:23nasal secretions. We have taste of the
26:26anterior twothirds of the tongue. Guess
26:28what else we have? One more. Remember I
26:30showed you that the spinal nucleus of
26:32the trigeminal nerve was connected.
26:35There was a connection to the facial
26:36nerve. I'll show it again in just a
26:37second. The reason why is do you guys
26:40remember what I told you? What pretty
26:42much the nuclei of the trigeminal nerve
26:44are responsible for? They're receiving
26:47information, sensory information from
26:50the face. What kind of sensations?
26:53Pain, temperature, touch sensations.
26:57Well, you know, another area that's
26:59actually really important that the
27:00facial nerve supplies, it supplies the
27:03middle and external ear and even the
27:05tempanic membrane. So, some of those
27:07sensations that you have within the
27:08tempanic membrane, the external ear and
27:11the uh uh the middle ear are actually
27:14picked up on sensory fibers of the
27:16facial nerve. Okay? And sent to the the
27:22spinal nucleus of the trigeminal nerve.
27:25Okay? So again this kind of maroon
27:27colored fibers I want you to remember
27:30that these are general sematic aerant
27:34fibers but these are fibers that are
27:37basically taking sensations okay they're
27:39going to be taking sensations from the
27:42uh external ear the middle ear and the
27:44tempanic membrane but these are going to
27:46be I just want you to remember these are
27:47sensory fibers and these sensory fibers
27:51are going to be sending this information
27:52to who to that spinal final
27:56nucleus
27:58of cranial nerve 5. Let me give you just
28:02a tiny explanation of that. So if you
28:05look here, let's just say that we take
28:06this part of the diagram. Let's say here
28:08is going to be picking up the sensations
28:09from the external ear, your tempanic
28:12membrane. These sensations will be
28:14picked up via the sensory fibers of the
28:16facial nerve. What kind of fibers?
28:18General sematic aerant fibers. They'll
28:20be traveling down this nerve.
28:24And as they travel towards what portion
28:29where are they going
28:31to that spinal nucleus of the trigeminal
28:33nerve okay so again that's what I want
28:35you to remember they're picking up the
28:38spinal nucleus of the trigeminal nerve
28:39is receiving sensations obviously pain
28:41temperature uh touch pressure even a
28:44teensy bit appropriate reception from
28:46the face but also from that external ear
28:48tyanic membrane and a little bit of the
28:50middle ear. All right, sweet deal. Let's
28:52move on to the next part part. Okay, so
28:56we covered the facial nerve. Okay,
28:58what's this guy here that it's wrapping
29:00around and we'll talk about what that
29:02little wrap around is called here
29:03because it produces a little depression
29:05in the back of the fourth ventricle. But
29:06let's talk about this nerve first. So,
29:08we already covered the facial nerve and
29:10how it wraps around this nerve. What is
29:12that guy called? That's called your
29:14abducins nerve. So, again, what is this
29:16son of a gun called here? This baby blue
29:19guy here that we talked about. This is
29:21your abdusen's nerve and thank the Lord
29:25the abdusen's nerve only has one fiber.
29:29Okay, so again this is your cranial
29:31nerve six and it only contains motor
29:35fibers. Okay, or those general sematic
29:38eerant fibers. So if you guys really
29:40want to remember that's your general
29:41sematic eerant fibers and these go to
29:44your lateral rectus. How do you remember
29:46that? LR6
29:48lateral rectus is supplied by the six
29:50nerve. So it plays a role with abduction
29:52of the eyes. Beautiful. We're done with
29:55that one. Thank goodness. Let's move on
29:57to the next structure.
29:59So we covered the abducins. We covered
30:01all the facial nuclei and their fibers.
30:04Okay. If we move out a little bit more,
30:06we got this guy here. Okay. You see
30:08these red structures here? What are
30:10these? Okay.
30:12This red structure here is actually a
30:14part of your vestibular nuclear complex.
30:16So again, what is it called? It's called
30:18your vestibular nuclear complex. So
30:21again, this is your vestibular
30:27nuclear
30:29complex.
30:31And this vestibular nuclear complex has
30:34a couple different portions. It has a
30:36superior nucleus, a medial comp portion,
30:40a lateral portion, and an inferior
30:43portion. What I want you to remember is
30:45that the superior, middle, medial, and
30:48lateral portion are situated at this
30:50level of the pawns. The inferior is
30:53situated in the upper part of the
30:55medulla. Okay? So, you won't be able to
30:57see it. Okay? So, again, superior,
30:59medial, and lateral at the level of this
31:01portion of the ponds. Inferior won't be
31:03able to see it. We'll talk about more
31:05detail what this guy does. He plays so
31:07many roles. If you guys want to know
31:08more about this in more detail, watch
31:11our video on the vestibular cclear
31:12nerve. Okay, sweet deal. Let's go into
31:15the next one. You see these green guys
31:18here? These green nuclei here and then
31:21in the center of it is another big
31:23structure. Okay, we're going to talk
31:25about those now. These guy guys are your
31:29coclear nuclei. Okay, so you have your
31:33coclear nuclei and if you guys want more
31:35detail on this, watch our video on the
31:36coclear pathway, the vstibular cclear
31:38nerve. But again, the cclear nuclei
31:41which are situated posterior to this
31:43brown structure or dorsal to this brown
31:45structure is called your dorsal cclear
31:47nuclei. So what are these called? Your
31:49dorsal
31:52cclear
31:55nuclei.
31:57Sweet. The structure, this green
31:59structure that's located anterior to
32:01this kind of brown structure is called
32:03your anterior or vententral cclear
32:06nuclei. So these are called your
32:08vententral
32:10cclear
32:13nuclei.
32:15Sweet.
32:17The next thing you have to answer is
32:18okay what the heck is this dud brown
32:20structure that's between these clear
32:22nuclei? This duty brown structure is
32:24actually the inferior cerebellar
32:26podunks. There's a tiny little piece of
32:28the inferior cerebellar preduns at this
32:31level of the pawns. Okay. So again, what
32:33is this tiny little structure here? It's
32:35called the inferior
32:37cereabellar
32:40podunks. We're just going to put
32:42podunks.
32:44Okay. So the inferior cerebellar
32:46podunkcle is separating posteriorly the
32:50dorsal cclear nuclei ventrally the
32:51vententralar nuclei. Now what I want you
32:54guys to know about this is
32:57the coclear nuclei are receiving
32:59information from the cclear branch of
33:01the vestibular cclear nerve. We'll get
33:03into more detail on that. But again if
33:05you have to remember these I want you to
33:07remember that these guys are receiving
33:09information from the
33:12vestibular branch of the vestibular
33:14cclear nerve. And guess what they do?
33:16They send their information down into
33:20the trapezoid body which will come out
33:22via the
33:25contrlateral lateral eminiscus. So again
33:27you'll have fibers coming in through
33:28this guy. The ventricle nuclei will send
33:31these fibers down through the trapezoid
33:34body. These that's basically what makes
33:35the trapezoid body is the crossing of
33:37the axons coming from the vententralar
33:40nuclei or what we call the vententral
33:42acoustic stri. Okay. It'll cross over
33:46and go to the opposite side and make the
33:48contrlateral li later lateral lin
33:50meniscus. Beautiful, right? Okay. Sweet.
33:55Next thing I want to talk about here, we
33:57have these green structures here. These
34:00green structures here are also very
34:03important. Again, we'll talk about them
34:04in a little bit more detail when we go
34:05over this kind of trapezoid body and the
34:08colear nuclei more detail. But what
34:10happens is some of these fibers from the
34:13trapezoid body that vententral acoustic
34:15stria basically will ascend upwards
34:18right and some of those fibers as they
34:20go upwards will synapse on these
34:22structures and they play a role with
34:24being able to play determine the
34:26intensity as well as kind of the
34:28relative velocity of auditory
34:31sensations. What are these guys called?
34:34These green guys here which we're going
34:35to kind of annotate here. These are
34:37called your superior olivary complex or
34:40nucleus. So this is called the superior
34:45olivo
34:47nucleus.
34:49Okay. So they play a role with the
34:50relative intensity, timing, velocity of
34:54auditory sensations and they're a very
34:56important component of that auditory
34:59pathway. We'll get into more detail on
35:00that a little bit. What else do we have?
35:04We have these guys. Remember these rubro
35:06spinal tract descending motor pathway to
35:08the flexors. Tetospinal tract helps with
35:11reflexive movements of the head and the
35:13eyes. And the medial longitudinal
35:15faciculus which is the connection
35:17between the sixth, the third and the
35:18fourth cranial nerves. Move a little bit
35:21back.
35:22Remember I told you that there was a
35:24thing called the facial caliculus. And
35:26basically what that is is whenever the
35:28facial nerve where we have it here, it
35:30kind of rolls around the six nerve. It
35:33puts a little depression into this
35:36portion of the fourth ventricle. So what
35:38is this structure here? Again, we still
35:40have the fourth ventricle,
35:46but there's a little depression on both
35:48sides here. What are those little those
35:49little divots called? This is called
35:52your facial
35:55caliculus.
35:58Let me let me give you guys a little bit
36:00better review of this to so you
36:01completely understand. Here I'm going to
36:03draw a sagittal section here. Okay. So
36:06here's your midbrain, here's your pawns,
36:08here's your medulla, and here's your
36:09spinal cord, right? And then here's your
36:11cerebellum. And then what we'll do here
36:13is we'll draw a little thing there for
36:16the fourth ventricle. Again, to explain
36:20it like this, here's your sixth nerve,
36:23your abducins.
36:25We'll put here in black here. This is
36:28your facial nerve nucleus. And again,
36:31all of those fibers that are coming from
36:32the multiple nuclei, they wrap around.
36:35And when they wrap around, they put a
36:36little divot into this little fourth
36:39ventricle, that little divot, which is
36:41formed by the turning of those facial
36:44nerve fibers, is called the facial
36:46caliculus. Okay? So that covers all the
36:50components within this section of the
36:53pawns.
36:54All right, guys. So now that we've
36:56covered pretty much the cross-sections,
36:58covered pretty much all the internal
36:59structures, things that are coming in
37:01and out of the ponds at the trigeminal
37:03level and at the facial nerve abdusins
37:06level. I kind of want to give just a
37:08general overview with different kind of
37:10like sections and uh so that we
37:12completely understand all of these
37:13structures. Just a general overview of
37:16what these structures are that are
37:17moving up, that are moving down, that
37:19are moving all over the place in these
37:21levels of the ponds. Okay, they're going
37:22to be very general. They're not going to
37:24be super detailed. I just want us to get
37:26the overall concept.
37:28First thing I want us to understand is
37:30that C the level FD corticopontto
37:33cerebellar fibers. Okay. So again, if
37:36you guys remember, we have these
37:37descending motor fibers. So here's your
37:40upper motor neurons, right? They're
37:41coming from the cerebral cortex. They're
37:44coming down.
37:46And as they come down, remember what
37:49happens? They move through the crust
37:51cerebri. And some of the fibers will
37:53scatter around the pontine nuclei and
37:56some will actually syninnapse on these
37:59pontene nuclei.
38:02When again some of these come together
38:04they move down to the level of the
38:05medulla at the pyramids cross over
38:08right. So some of these will reccome
38:09together cross at the level of the
38:10pyramids and come over here. Okay. What
38:15I want you to remember is that some of
38:16these fibers that are coming down here
38:18that stop at the pontine nuclei, they'll
38:20synapse on these pontene nuclei, right?
38:24These pontene nuclei, what did I say?
38:26They'll send their fibers, their
38:29pantoereabbellar fibers to the
38:31contraateral
38:33cerebellum via the middle cerebellar
38:36podunkcle. So the middle cerebellar
38:37podunks are basically these structures
38:39here that are connecting the cerebellum
38:42to the ponds. Right? So again cortex
38:45coming down to the pontine nuclei
38:46syninnapse on some of those pontine
38:48nuclei. The pontine nuclei will send
38:50their fibers via the panto cerebellar
38:53fibers via the middle cerebellar podunks
38:57to the contraateral cerebellum. What is
39:00the purpose of this?
39:02What will happen is you have a motor
39:05plan. Motor plan's coming down to go to
39:07the muscles. You perform a movement.
39:09Your cerebellum is also going to be
39:10receiving sensory information from a
39:12bunch of different propritors from those
39:14muscles that are firing. Your cerebellum
39:17receives that information from all these
39:19sensory pathways.
39:21It also receives the previous motor plan
39:24that came down from the cortex. It takes
39:26all that information, sifts through it,
39:28and then guess what it'll do? It'll send
39:31that information
39:34back up to the cerebral cortex and say,
39:36"Hey, I took into consideration the
39:38movement that you had planned. I
39:40received all the sensory information
39:41from the muscles, the tendons, the joint
39:43capsules. I put it all together. Put
39:45came up with the next perfect motor
39:46plan. Here's what you need to do." Isn't
39:49that cool? So again, that's the thing I
39:51want you guys to understand with those
39:53pontine nuclei, the pontto cerebellar
39:55fibers, and again the middle cerebellar
39:57podunks. Okay. Next thing, again, we've
40:01talked about these fibers in so many
40:03videos. We're going to make this very
40:05general. We're going to go over some of
40:06those susciniscus
40:12and we'll kind of work our way outward.
40:14So, we'll do medial liniscus here in
40:15purple here. Right. So, medial
40:17luminiscus, what does it do? It receives
40:19sensory information from proprio
40:21receptors for frying and discriminative
40:23touch for vibrations. And what does it
40:26do? It sends that information inwards,
40:29comes into the dorsal grey horn and
40:32moves into the dorsal grey horn and
40:34ascends upwards on the epips epsilateral
40:35side comes to the medulla where it has
40:38nuclei like the nucleus cuniatus and the
40:41nucleus graasilus right synapses on
40:44these nuclei in the medulla and then
40:46what happens these guys will form those
40:48that aruate fibers the internal arcuate
40:50fibers which will cross and ascend
40:52upwards and as it ascends upwards it
40:55eventually goes goes to the phalamus.
40:58Where is these medial luminiscous
41:00fibers? Remember they were at the ponds
41:02at both levels. So that's again picking
41:05up sensory information from
41:07propriception, touch and vibrations.
41:11What else do we have? Let's do the
41:14maroon as the trigeminal. Again the
41:16trigeminal nerve remember you have the
41:19spinal nucleus here.
41:22You have the central uh principal ponte
41:25nucleus and the misen syphalic nucleus,
41:28right? And these guys are receiving
41:31information from the the trigeminal
41:34nerve, all those sensory fibers. And
41:37from these nuclei, they basically send
41:40up
41:43their axons as the
41:46trigeminal liiniscus. So again, you're
41:48going to have the what is this here? The
41:50misinphalic nucleus. the central or
41:52principal ponte nucleus and the spinal
41:54nucleus. They're going to be receiving
41:56information, pain, temperature, touch,
41:59uh, vibration, all of those things from
42:02the face and sending it to these
42:04individual nuclei. And these individual
42:07nuclei will send up their axons
42:10as the trigeminal luminiscus. Okay? So
42:14again, purple here is medialiniscus.
42:18The maroon here is the trigeminal
42:21liiniscus. What else do we have? Let's
42:24do the next one in uh this kind of like
42:26duda green color. This is your spinal
42:27liniscus. Do you guys remember what
42:29happens with a spinal liniscus?
42:31Spinal laminiscus. You're picking up
42:33pain, temperature, crude touch, and even
42:36some pressure. That sensory information
42:39is coming in. It's synapsing on that
42:41dorsal gray horn. If it's pain and
42:43temperature, where is that going?
42:45Lateral. If it's going to be crude touch
42:48and pressure, where will those fibers
42:49go? Vententral. Either way, they'll
42:52eventually ascend upwards
42:55and come together.
42:57And when those fibers come together from
42:59the vententral spinal tract and the
43:02lateral spinal tract, they'll ascend
43:05upwards as the
43:07spinal lemonus. Okay. So again medial
43:12liin miniscus is carrying that
43:14propriception
43:16fine discriminative touch and uh some of
43:18the vibrations. Trigeminal liiniscus
43:20carrying all those sensations from the
43:22face spinal liniscus carrying pain
43:24temperature crew touch pressure from the
43:27basically from the neck down. Okay
43:31that covers those. And if you guys
43:32really want to remember here remember we
43:34said that there was also another
43:35ascending pathway that vententral spinal
43:37cerebellar tract. If you guys really
43:40want to remember that one, it's also
43:42kind of doing the same thing here as
43:44this pathway here. It's picking up
43:47sensations. What kind of sensations?
43:49It's picking up sensations from proprice
43:51from muscle, tendons, joints from L2, L3
43:55level down to the coxix. Okay? And it
43:58sends that information into the dorsal
44:00grey horn, crosses over to the lateral
44:02white column, and ascends upwards. And
44:05what do we say it does? it goes into the
44:08superior cerebellar podunks to the
44:11contrlateral cerebellum. Okay.
44:15Okay, that covers that one. And again,
44:17if you guys really want to remember what
44:19happens here, once it goes through the
44:21superior cerebellar podunks, it actually
44:22will go into this part of the cerebellum
44:25and actually move behind and go to the
44:29opposite cerebellum. So again, just a
44:31little tiny piece of information there.
44:32Technically the vententral spinal
44:34cerebellar tract will take propriception
44:36from the same side to the same
44:38cerebellum. It just goes up through the
44:40superior cerebell cerebellopunals of the
44:42contrlateral cerebellum and then moves
44:44around the midbrain to the other
44:46cerebellum. Pretty crazy. But again this
44:49covers a lot of those tracks that we
44:51talked about and puts a name and a kind
44:53of an idea behind all of those
44:55structures. Okay, now that we covered
44:58some of those sensory pathways, let's
44:59cover another one which is basically
45:01that vestibular nuclear complex.
45:04Okay,
45:05so if you guys remember we have your
45:08vestibular cclear nerve. Remember the
45:10vestibular cclear nerve is going to be
45:12receiving information from your your
45:15ears, right? Particularly from the inner
45:17ear. So it's going to be coming from
45:19that christ ampularis and the vestibule,
45:22right? And what happens is that
45:24information will come in and when it
45:27comes in, it'll actually move over here
45:30and synapse on these vestibular nuclear
45:34complex. So again, this is coming from
45:35your inner ear. Okay? Picking up your
45:38dynamic and kind of static equilibrium.
45:41Okay? So movements of your head, up and
45:43down movements, all that stuff from the
45:46ears, it'll send it to your vestibular
45:47nuclear complex. Do you guys remember
45:49what your vestibular nuclear complex
45:51does? It actually can send information
45:55downwards
45:58and go down to your muscles. Okay? So,
46:01it actually will go down to your muscles
46:03and it'll actually cause stimulation of
46:06the muscles that are going to be
46:10going to
46:12extensor. So, it's going to actually
46:13stimulate your extensor muscles. Okay?
46:16And that's called your vestibular spinal
46:19tract. And I just want you to remember
46:21that's going to your extensor muscles.
46:23Okay, your anti-gravity muscles. That's
46:25one thing. So it helps you to kind of
46:27keep your balance and your posture
46:28whenever there is this movement. Okay.
46:32The other thing it does, it sends
46:34information from the vestibular nuclear
46:36complex via the inferior cerebellar
46:38podunks to your cerebellum. Do you guys
46:41remember that nucleus in the cerebellum?
46:43This was called that vestigial nucleus,
46:46right? or that juxar rest form body that
46:48you have the connection between. This
46:50helps us to maintain again a dynamic
46:52equilibrium. Again cerebellum wants to
46:54receive all kinds of sensations because
46:56it is important for posture, for
46:58balance, for coordination.
47:00Vestibular nuclear complex also does
47:02what else? It sends a stimulus to the
47:05contrlateral six nerve. Then that
47:09contraateral six nerve, guess what he
47:11does? He'll Let's do this in a different
47:14color. Let's do it in green.
47:16This sixth nerve will send information
47:19upwards
47:21to the contraateral third nerve and
47:25fourth nerve. So again, you're going to
47:27have 346.
47:30You're going to have vestibular nuclear
47:32complex stimulates the contrlateral
47:33sixth nerve. The contrlateral six nerve
47:36will then move over and stimulate the
47:38contrlateral third and fourth nerve
47:41nucleus. Guess what this structure is
47:44called? the medial longitudinal
47:46faciculus and we saw that at both
47:48sections. Okay, so we've already covered
47:51the vestibular nucleus, we covered the
47:53medial longitudinal faciculus and we
47:55already talked about the abdusen's
47:56nerve. Okay, that covers some of that
47:59structure. Now let's move on to the next
48:01thing here which is coming down here to
48:04talk about the cclear pathway. All
48:06right, so we talked about the vestibular
48:07nuclear complex. We reviewed the medial
48:09longitudinal faciculus. Let's now talk
48:11about these cclear nuclei. Okay. And the
48:14superior olivary nucleus which we said
48:16we talked about remember coming from the
48:18cookia again the vestibular cclear uh
48:21complex is connecting between the
48:23vestibule right the cristampularis so
48:26your inner ear playing a role with
48:27dynamic and static equilibrium. The
48:30cookia on the other hand is taking
48:32information for auditory sensation
48:34hearing. Okay nothing to do with
48:35equilibrium.
48:38These cclear fibers that are part of the
48:40vestibular cclear nerve will actually
48:43syninnapse okay on these cclear nuclei
48:47which we already talked about right and
48:48again you have the cclear nuclei which
48:50is the dorsal cclear nuclei here in the
48:52back and the ventrical cclear nuclei
48:54here in the front and again what
48:55separates those is the inferior
48:57cerebellar podunks right
49:00these cclear nuclei what did we say
49:03happens some of these guys will actually
49:05go upwards and form formed like that
49:08dorsal acoustic and intermediate
49:09acoustic stria. But a lot of them from
49:12the vententral cclear nucleus will cross
49:15over
49:17and when it crosses over it'll synapse
49:20on that superior olives right that
49:23superior olivary nucleus. So again some
49:25of these fibers will just cross right
49:27over won't go to the olives and then
49:29some of the vententral acoustic stria
49:31fibers will cross over and then stop at
49:34those superior olives. Either way, all
49:37of that crossing that you have here, all
49:39of this
49:41is that trapezoid body. That's where all
49:43those fibers from the cclear nuclei
49:46which are moving to the contrlateral
49:48side whenever they're crossing. That's
49:49what's forming that trapezoid body. Then
49:53some of these fibers will syninnapse on
49:54the superior olivary nucleus and the
49:57superior olivary nucleus will also give
49:59off some fibers that'll move with some
50:02of these other fibers coming from the
50:04clear nuclei that didn't synapse. These
50:07guys will come up and whenever they come
50:09up this structure here that we formed
50:12after the trapezoid body this right here
50:15is your lateral lemoniscus. Okay? And
50:19again, if you guys remember, the lateral
50:20li meniscus will come up. It's taking
50:22auditory information. So, it'll actually
50:24go all the way to this structure here
50:28called the
50:30inferior caliculus. And from the
50:33inferior caliculus, the brachium of the
50:34inferior caliculus will connect to the
50:37phalamus. And then from the phalamus
50:39this will send that information
50:41to the primary auditory cortex or the
50:45remember the superior temporal gyus or
50:47the transverse gyrus of hessel that's
50:49that auditory information but again I
50:51wanted to kind of give you an idea what
50:52is the trapezoid body it's the crossing
50:55of the fibers coming from the cclear
50:57nuclei and the lateral lmeniscus is
50:59basically taking up it's the ascending
51:02fibers of that auditory pathway moving
51:05up through the pawns through the
51:06midbrain terminating at the inferior
51:09caliculus. And again, some of these
51:11fibers that are crossing after the
51:12trapezoid body, some of them do synapse
51:15on those superior olives to give a roll
51:18with relative intensity, relative
51:20timing, and velocity of sound. Sweet
51:23deal. Next thing I want you guys to
51:25remember here is going back to that
51:27tetospinal and that rubro spinal. Again,
51:29we're not going to go into crazy detail
51:31because we've already talked about this,
51:32but I just want to give you guys an
51:33understanding. Remember what the tectum
51:35is? The tectum is going to be the
51:37superior caliculus and the inferior
51:38caliculus, right? That dorsal part of
51:40the midbrain. That tetospinal tract is
51:43going to be descending motor fibers that
51:46are giving off connections to your
51:49cranial nerve nuclei that play a role
51:51within movement of the eyes. So third,
51:54fourth, six and down to the lower motor
51:58neurons in your spinal cord that'll go
52:00to the muscles of the head and the neck
52:02to move the eyes. Right? So again
52:04tetospinal tract is the motor fibers
52:07going to muscles of the eye and muscles
52:10of the head and the neck for movement.
52:12If the stimulus is coming from the
52:14superior caliculus that's visual
52:16stimulus.
52:18If it's going to be inferior caliculus
52:20that's auditory stimulus.
52:23Okay simple example again you're seeing
52:26somebody that's walking you're moving
52:28your head and your eyes towards that
52:30direction. You hear someone yell your
52:32name over here. When you hear them yell
52:34your name, you look towards that
52:35direction. You fix your eyes, your neck,
52:37and your gaze towards that area. If
52:39you're tracking, superior caliculus, if
52:40you're moving in response to an auditory
52:42stimulus, inferior caliculus. Simple as
52:44that.
52:46The other one, this red guy in the level
52:48of the midbrain. Here we have the red
52:50nucleus. And the red nucleus is sending
52:53down these descending motor fibers that
52:56are going to be going to muscles that
52:58play a role with flexion primarily the
53:00upper extremity distal flexors. Okay,
53:04this tract is the rubropppinal tract. So
53:08again putting an idea or concept behind
53:10the tetospinal and the rubospinal tract.
53:13What are their functions? We already
53:15know. Okay, sweet. Let's move on to the
53:18next thing. The next thing that we have
53:20to talk about here is going to be
53:22looking at that ventricular system.
53:24Again, I just wanted to give a different
53:25view. Okay? So, if you look at a
53:27sagittal view here, we have this kind of
53:29like horn structure here. This is our
53:32lateral ventricle. So, we're just going
53:33to kind of like abbreviate this lateral
53:35ventricle. Then, connecting the lateral
53:37ventricle to this third ventricle. Okay?
53:41So, this is the third ventricle
53:43is this little connection here called
53:45the interventricular fammen or the
53:47fammen of Monroe. Then the third
53:50ventricle drains down via the cerebral
53:53aqueduct. And then from the cerebral
53:55aqueduct at the level of the pawns and
53:57the medulla we get the fourth ventricle.
54:01And then the fourth ventricle can
54:03continue downwards as the central canal.
54:07Okay? Or it can come out and go into the
54:09subraacttoid space via the median and
54:11lateral apertures.
54:13to give another view. This is going to
54:15be looking at that ventricular system
54:17from the posterior portion. Okay? All
54:20right. So again, here you're going to
54:22have
54:24midbrain.
54:25Here you're going to have pawns.
54:28Here you're going to have the medulla.
54:31If we look here, this obviously is the
54:33cerebra aqueduct. And then this whole
54:35thing here is the fourth ventricle.
54:37Sometimes they might ask questions in
54:40regards to the external structure. So
54:42really quickly, what is this line here?
54:44Right down the middle. This is called
54:47the median sulcus. We're not going to
54:48write down. Just want you to remember
54:50it. Okay, that purple, that pink line is
54:52the median sulcus. The next thing
54:56sometimes they'll ask what is this
54:57structure here? These kind of like black
54:59kind of structure here on the sides of
55:02that median sulcus. And that black
55:04structure there on the side of the
55:05median sulcus is called the median
55:08eminence. Okay. At the bottom of the
55:12median eminence, there's a little divot
55:14here. Let's do this one in green.
55:17This little divot here in the on the
55:19bottom of the median eminence is
55:20actually called your facial caliculus.
55:24Okay, that's that little depression in
55:26the back of the pawns formed by when the
55:28facial nerve turns around. Okay, so
55:31again, pink line, median sulcus, black
55:33structure on the side of it is the
55:36median eminence. The bottom of the
55:37median eminence is going to be the
55:39facial caliculus.
55:41The last thing is on the outer parts
55:43here. Let's do this in red. On just
55:45outside of the median eminence
55:49is called your sulcus limits. Okay. So
55:52sometimes they might ask you this. What
55:54is the median line structure? It is
55:56called the median sulcus. On the sides
55:58the median eminence at the bottom is the
56:00facial caliculus and all the way lateral
56:02is the sulcus limitance. Last thing I
56:04need to tell you is there's a kind of a
56:06horizontal line here coming from this
56:09portion here to this portion here. This
56:12here this brown structure is called the
56:14stria medularis. The stryularis
56:18is important because above the
56:21striularis that portion of the fourth
56:23ventricle is actually going to be formed
56:26by the back of the pawns. below the
56:29stria medularis that portion of the
56:31fourth ventricle is actually going to be
56:32formed by the back of the medulla. So
56:35sometimes they might ask you that
56:36question as well. Okay, last things that
56:40we got to talk about here. We got to
56:42talk about the abducins nerve. Okay, and
56:44again this is very general. We're not
56:46going to go into tons of detail here. We
56:47already talked about these in great
56:49detail in these individual videos. But
56:51if you guys remember the abdusen's
56:53nerve, what extra ocular muscle does
56:57this bad boy supply? It supplies the
57:00lateral
57:03rectus. And again, what does the lateral
57:04rectus do? He plays a role in abduction
57:08of the eyes. Okay, done.
57:11Facial nerve. Again, we'll go into more.
57:14You can go and watch our video. We go
57:15over this in way more detail, but I want
57:17you guys to get the basic concept here.
57:18What does it do? If you have those
57:21fibers that special visceral eer fibers
57:23the second fingial arch is supplying all
57:25the muscles of facial expression. So it
57:28supplies muscles
57:31of
57:33facial
57:35expression.
57:37Okay sweet salvatory nucleus. What does
57:40that guy do? He's taking the actual
57:42sensations from where? He's actually
57:44sending visceral eerant information to
57:46where? to the lacrial glands to the
57:48nasal glands and to your salivary
57:50glands. Okay, so it's also going to play
57:53a role in lacrimmation
57:58and salivation.
58:01Okay, sweet.
58:03What else? We're also going to have that
58:05nucleus of tractus solitarius. What is
58:07that guy doing? It's taking sensory
58:09information of taste from the anterior
58:11twothirds of the tongue. So, it's also
58:13going to play a role in gustation. What
58:16is gustation? Gustation is taste. Okay.
58:19And again, we'll put here 2/3 anterior
58:23two/irds of the tongue.
58:25The last thing is it's also going to be
58:27taking up from that uh spinal nucleus of
58:30the trigeminal nerve. You guys remember
58:31what that picks up? The general sematic
58:33eerance, which is the pain, the touch,
58:35the temperature sensations coming from
58:36the external ear and the tempanic
58:38membrane and a little bit of the middle
58:39ear. So, it's also going to pick up
58:43uh sensations
58:46from
58:47ear. Okay. And again, just remember
58:51external ear, middle ear, and tempanic
58:53membrane.
58:55Okay. The last sucker that we got to
58:57talk about here is the trigeminal nerve.
59:00And again, we already covered this in
59:01great detail in the trigeminal nerve
59:03video. Just to do a very basic overview,
59:05trigeminal nerve, we have those special
59:08visceral eerant fibers supplying the
59:10first fingial arch. That's going to be
59:12the muscles of mastication. Okay? So,
59:15it's supplying the muscles
59:19of mastication. And again, what nucleus
59:21is that going to be coming from? That's
59:23going to be coming from that motor
59:25nucleus of the trigeminal nerve.
59:28What was the other nucleus of the
59:29trigeminal nerve? I'm glad you guys
59:30asked because we got a bunch of those
59:32right at this level at the midbrain.
59:34Right. So, we have the midbrain here.
59:36We'll have like a kind of line here to
59:38separate each portion. We have this
59:40portion here midbrain is above that.
59:43Here
59:45we have the pawns and then here we have
59:47the medulla. Okay. At the midbrain level
59:50what is this nucleus here called? The
59:52misen syphalic nucleus.
59:58Okay. What is this one called? That
1:00:00principal or central pontene nucleus.
1:00:04And this one here which is actually a
1:00:06little bit in the lower part of the
1:00:07pawns and the medulla is the spinal
1:00:12nucleus of the trigeminal nerve. What
1:00:15are all of these guys receiving?
1:00:17This one's primarily receiving
1:00:19propriioceptive information from the
1:00:21muscles of the jaw. The principal is
1:00:24primarily receiving fine and
1:00:25discriminative touch from the face. A
1:00:27little bit of propriception. And the
1:00:29spinal nucleus is receiving pain,
1:00:31temperature, touch, pressure, and a
1:00:33teensy bit of propriio reception from
1:00:35the face. Easier way to say that is all
1:00:38the sensations of the face. Okay,
1:00:42so sensations
1:00:45of face. And again, if you guys want
1:00:48more detail on all of those different
1:00:49areas of the face, go watch our video on
1:00:51the trigeminal nerve. Okay, but that
1:00:53covers all these different parts here.
1:00:54All right, engineers. So, in this video,
1:00:56we talked a lot about the pawns. I hope
1:00:58it made sense. I hope you guys did enjoy
1:01:00it. If you guys did, please smash that
1:01:02like button, comment down the comment
1:01:04section, and please subscribe. Guys,
1:01:06thank you if you guys stuck in
1:01:07throughout this entire video. I
1:01:09appreciate it. I hope this helped you
1:01:11guys. Also, if you guys want to get in
1:01:13contact with a little bit more, we have
1:01:14down in the description box links to our
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1:01:23for everything you do, ninja ners. And
1:01:24as always, until next time.
1:01:31[Music]

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