Alright Ninja Nerds, in this video we are going to talk about the dorsal column medial limoniscal pathway. This pathway is super, super important because it controls a lot of our touch, our proprio reception, pressure, vibration, stretch. So we're going to go into this pathway in great detail, so let's go ahead and get started. So if we come over here, we're going to talk first off Again, what are we going to talk about? The main topic here is the dorsal column medial limoniscal pathway.
Okay? So that's what we're going to talk about in this video. That's one heck of a name.
Now the dorsal column medial limoniscal pathway. We said that it is going to be important for carrying what types of sensations? Okay, so the dorsal column medial and meniscal pathway is important for being able to pick what's called, pick up discriminative, discriminative touch.
So fine and discriminative touch. What does that mean? Sometimes you might even hear it as what's called two-point touch.
This is really important. So two-point touch or fine and discriminative touch. Imagine me taking my fingers and me poking different parts.
of my hand. My eyes are closed. Let's say that I close my eyes.
Either it could be my eyes closed or my eyes open and I'm touching my hand at two points and I can tell that there is two points of contact. That is what this system is really good at. So find the discriminative touch.
And we'll talk about what type of receptors pick that up. Another thing it's really good at is what's called picking up pressure and stretch of like the skin. So we'll be able to pick up pressure placed on the skin, stretch of the skin, and another thing that it can pick up is vibrations, and even vibrations.
Okay, there's some special receptors we'll talk about with this. But really, really, really important one is what's called proprioception. So another one that is extremely crucial here is called proprioception.
So we have to define what proprioception is. So proprioception is when you have a patient who has a problem with their is basically knowing one's position of their joints, their ligaments, their muscles in space. So me being able to know that my arm is over here, my finger is on my nose, is now on my eye, it's on my chin. I'm actually aware of that. Even though my eyes are closed, I'm consciously aware of where my hands are right now.
That is what proprioception is. And it's really important because our cerebellum and our central nervous system, cerebral cortex, has to be aware of that. these types of situations. Okay, so remember that. Now one more thing, this dorsal column medial meniscal pathway is what's called an ascending tract.
Okay, this is specifically it's an ascending tract because we're talking about ascending tracts. Now how would you talk, how would you define a tract? This is really important.
A tract is a bundle of axons in the central nervous system. Okay, So a tract is a bundle of axons in the central nervous system. Ascending means it's going up. So let me say here I draw a cross-section, not a cross-section, a sagittal section of the central nervous system. Right here is spinal cord, medulla, pons, midbrain, and then a cerebrum.
If we talk about a tract, a tract is going to be, let's say that here's this axon here and it's coming out with this peripheral process, picking up some type of stimulus. So there's a stimulus out here. Here's the stimulus and the stimulus is going to activate some receptor. The receptor is connected to some type of cell body, we'll talk about this. That gets projected into the actual spinal cord and then goes up.
And it goes up to specific parts of the central nervous system. Well you have many of these that are collectively, so imagine here, let's pretend that this is at the lumbar region. Let's pretend that this is at the thoracic region. This can get added on.
Let's pretend that this one is here at the cervical region. This one can get added on. So this bundle of axons here running through the central nervous system is what's called a tract. And because it's going up to the central nervous system, it's referred to as an ascending tract.
There's many of these. We're going to talk about the dorsal column medial limoniscal pathway. We'll talk about the anterolateral system or the spinothalamic tract. And we'll talk about the spinocerebellar tract and some other accessory ones.
But just remember what is a tract? It's a bundle of axons in the CNS. That's super important. Now, let's go ahead and talk about, so we know what this dorsal column is specifically responding to, the types of stimuli. But now we have to understand how do we pick up that stimulus.
Alright, so let's go ahead and talk about that. So let's come over here. So we know that the dorsal column is specifically responding to discriminative touch.
Okay, how does it do that? There's special receptors. So you know, there's receptors.
If you imagine here, pretend I take like a very crude diagram of the skin, all right? Here's your epidermis. You know the epidermis, you have these little peg-like projections right here? There's special receptors in here called Meissner's corpuscles, and these guys are actually going to be right here in the dermal papilla, and they pick up very fine and discriminative touch.
So what could you have over here? Let's pretend that this is actually the guy. Here it is.
Boom. There is our Meissner's corpuscles. Alright, so first one here is going to be your Meissner's corpuscles. Okay, what else? Another one that's really important is it's actually kind of situated.
You know, there's different stratum of the epidermis, like the stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and then the last one, which is right here on this edge, right above the dermal papilla, is the stratum basal. The stratum basale has specific types of receptors here that pick up very fine touch and very superficial pressure. What are these guys called? They're called Merkel's discs. So you're also going to have some other structures here, and these are going to be called your Merkel's discs.
They respond to very, very fine touch and also superficial pressure. All right, what else do we have? We have other ones here too. that are actually a little bit deeper.
They can be found in the dermis, the hypodermis. You can find them in your interosseous membranes. You can even find them in the actual mucous membranes of your GI, urinal, genital tract. They can be found in many different places. And these are called your proscenium corpuscles or your lamellated corpuscles.
So what's another one here that we could have? We could also have the proscenium corpuscles. So we can have what's called proscenium corpuscles.
Wow, there's so many of these darn things. So you have Meissner's corpuscles, Spassinian corpuscles, Merkel's discs. What else do we have?
I'm glad you asked. Let's pretend here is actually going to be a hair follicle. Right? So here's your hair follicle.
Around that hair follicle, to be able to pick up the bending and the movement of the hairs, you have special types of nerve fibers there. Right here around it, picking up different movements in the hair. That is going to be called the peritracheal.
Nerve endings. So what else do you have here? You also have what's called the peritracheal nerve endings. So many darn things.
Okay, another one. And this responds specifically to like the stretch of the skin. Okay, so it's responding to the stretch of the skin and vibrations.
Let's do this one in this. Orange color. Ooh, yeah. Let's do this one. So this last one here, it can be found in the dermis.
It can be found in the hypodermis. You can find it even in your joint capsules. And it's responding a lot to stretch of the skin and even vibration senses.
So these are called your ruffini corpuscles. Sometimes they even call them bulbous corpuscles. Okay? So you have your ruffini corpuscles, which respond to the actual. specifically vibrations and stretch of the skin, peritracheal nerve endings which are responding to the bending of the hair, and a little bit of touch, Pacinian corpuscles which are responding to deep pressure, and Merkel's discs which are responding to very fine touch and superficial pressure, and then Meissner's corpuscles which are actually going to be responding to fine and discriminative touch.
The Pacinian corpuscles, they respond a little bit more to vibrations than Ruffini does. Ruffini is mainly for stretch. But, pacinian, it can respond to a little bit of vibrations, but pacinian is mainly for the actual vibrations. Okay?
So, we got all these. That's for the discriminative touch. That's for the pressure. That's for the actual stretch and the vibrations. Now, we have one more that we have to pick up.
That's proprioception. This pathway is so unbelievable. It really is.
So, there's another one. In our muscles, you have, we'll talk about this more in other videos maybe, but when we talk about the muscles. right, our skeletal muscles.
We can break it down into two different components, right? So you have what's called extrafusal and then you have what's called intrafusal. Okay, muscle fibers.
We'll put intrafusal fibers though. So you have intrafusal fibers and extrafusal fibers. The extrafusal ones are the main ones that are contracting.
They're pretty much the bulk of the muscle. The intrafusal fibers have different types of, they're basically being able to detect stretch. Okay, there's actually two types here.
Okay. One is called nuclear chain fibers, and the other one is called nuclear bag fibers. And what these do is, is they respond to stretching of the muscle.
So whenever the muscle is stretched, it can activate these nuclear chain fibers and nuclear bag fibers. If you really want to be specific, nuclear chain responds to the actual onset of the stretch of the muscle. Nuclear bag responds to the progression, the progressive stretch of the muscle. Now, these guys are picking up stretch, alright, of the muscles. So let's actually represent these guys coming from here.
And what are these guys here? These ones are going to be the proprioceptive fibers, which are coming from the nuclear chain and the nuclear bag fibers, okay? So that's going to be important.
So these are going to be coming from the, we also give them another name, we also call them muscle spindles, but they have a name for this fiber type. They call this type 1a fibers. Okay, so they call them type 1a fibers.
Okay, and these are coming from your actual nuclear chain and nuclear bag fibers. Now, there's another thing. You know there's tendons, right? Tendons are connecting the muscles to the bone.
Well, in the tendon, you have a receptor that picks up the stretching of the tendon. So, whenever your muscles are contracting, let's pretend... For whatever reason I'm trying to curl some extremely heavy weight. So I'm getting my gains on and I'm just, yeah! So I'm trying to lift it.
And I'm stretching the muscle, right? But as I'm doing that, let's say that the tendon, the weight is just way, way, way too heavy. And it's really pulling and pulling on the tendon.
To the point to where it's getting ready to evolve from the bone. We have a protective response for the most part obviously. that can tell our body, hey, this is too much stretching on the tendon, that it's going to evolve pretty soon.
We need to protect that from happening. So there's special receptors located in that tendon that respond to the stretch of the tendon. And these guys, these receptors here called your Golgi tendon organs.
They're going to put GTO here. Okay, Golgi tendon organs. They respond to the stretch of the tendon.
And they're being carried down through what's called 1B fibers. Okay? And all of this information, look how much information is coming in here.
We're going to have information coming from the Meissner's corpuscles, coming from the Merkel's discs, the Pacinian corpuscles here. So many of these structures here. So what else do we have?
We have the Pacinian corpuscles. We have the peritracheal nerve endings. We even have the Ruffini corpuscles. All this stuff is going to be going into the central nervous system. It's unbelievable.
What else? Ruffini corpuscles. Okay guys, so I just brought all these guys together because all of these fibers are going to be going into the actual spinal cord.
Now, before we do that, right, so we know what the dorsal column is responding to, what stimuli. We know the receptors that are picking up those stimuli. Again, these guys being the proprioceptive aspect. But now I need to talk about one type of thing here. This pathway, this dorsal column median liminiscal pathway is extremely fast.
It's an extremely fast pathway and there's a reason why. Remember we talked about this a couple times before, but there's different types of nerve fibers, okay? Different types of nerve fibers.
There is what is called A, B, and C nerve fibers. Only thing that differentiates them is their degree of myelination. A being the most myelinated all the way till C being the least myelinated, where B is actually going to be moderately myelinated.
C is actually pretty much, sometimes we even say it's not myelinated. This being the slowest conducting fibers, medium conducting fibers, and the fastest conducting fibers. But here's the thing.
A can actually branch out into a couple different types. There's A alpha, there's A beta, and there's A delta. Delta is more for the fast pain, the prick pain, right?
And even for some crude touch and pressure. A alpha. is for the muscle spindles and the Golgi tendon organs.
So this is specifically going to be for the muscle spindles and for the Golgi tendon organs. organs. The A-beta is for all of these. The Meissner's corpuscles, the Merkel's discs, the Bissinian corpuscles, the peritracheal nerve endings, Ruffini corpuscles.
Now, what's the difference? The A-alpha is the fastest. So the fastest one is going to be the A-alpha. This thing can travel up to about 120 meters per second. That's insane.
This one being the slowest of. these A fibers, okay? Traveling up to about 30 meters per second.
The A beta is right in between, right? So A beta is for more of these actual pressure, touch, vibration, and discriminative touch sensations, all right? Now, now that we've done that, we have to take these fibers into the spinal cord, right?
So we make cross sections of the spinal cord here. So if we take these cross sections, there's two cross sections here. One over here, This is going to be, for the sake of simplicity, we're going to make this the cervical part of the spinal cord, and we're going to make this one over here the lumbar part of the spinal cord.
Okay? Now watch what happens here. When we talk about this, actually you know what we're going to do?
Make it even easier. We're going to kind of add on to this. Cervical, we're going to actually kind of refer to this because there's an important functional aspect here. We're going to say above T6.
And we're going to refer to this as below T6. And there's a reason why I'm talking about that sixth part. And the reason why is we're going to talk about two different types of fasciculi.
All right? Trust me for right now. We'll cover it. So now what I'm going to do is I'm going to take all these fibers here.
We're going to bundle them together. And these fibers here are going to be coming in to this first order neuron. And where is this first order neuron located? Remember. It's located in what's called the dorsal root ganglion, which is in the posterior root of the dorsal root.
And a ganglion, what's a ganglion? A ganglion is a group of cell bodies located within the peripheral nervous system. So this is our dorsal root ganglion with our pseudo-unipolar neuron there. He has his central processes projecting into the posterior or dorsal gray horn. From here.
These fibers will then funnel in without synapsing into this part right here. You see how we have this little separation here, this dorsal median sulcus here? We have this little dorsal median sulcus or fissure here in the posterior aspect. And closest to that fissure is going to be this fasciculus that we're going to talk about, which is going to be developing below T6.
This one right here, this fasciculus that we're going to talk about is called the fasciculus gracilis. We'll talk about this more. We're going to just bring this guy up for right now though.
So we're going to bring him up and here he is coming up this way. Alright, so here's my fasciculus gracilis. So the fasciculus gracilis is picking up information from below T6. So it's picking up from the limbs, the legs, the lower body trunk. So what is this structure right here called?
This one is called the fasciculus gracilis. And again, the fasciculus gracilis is taking information from the lower limbs and the lower body trunk, or specifically we can say from below T6. Now, at the same time, we're going to have, let's bring different color just for the sake of making it look pretty here.
Let's say that these fibers, these... Merkel's disc, Meissner's corpuscles, Bissinian corpuscles, peritracheal nerve endings, Ruffini corpuscles, muscle spindles, Golgi tendon organs, all this stuff is coming at the cervical level or above T6. When that happens the information is going to get funneled into the dorsal gray horn and again what is this part here guys don't forget this is the dorsal root ganglion. From here the central processes are going to project in to the dorsal white column.
You know the dorsal white column is all this part here. This is the lateral white column, and this is the ventral or the anterior white column. So what it's going to do is it's going to funnel in, though, lateral to this.
It's going to funnel in lateral to this. So this structure right here, which is funneling in lateral, is going to be a different type of fasciculus. This fasciculus is called the fasciculus cuneatus.
Now here's how I like to remember it. The gracilis muscle is in your leg, right? So fasciculus gracilis is picking up information from the lower limbs. It's an easy way to remember it if you want.
fasciculus cuneatus as due to that left over you can say okay that's going to be coming from the upper limbs and the upper body trunk so now fasciculus cuneatus fasciculus gracilis these are going to be coming up through the spinal cord right specifically within the dorsal column now there's one more thing that i have to talk about because there's what's called a somatotopic arrangement here if you notice something let's actually come over to this diagram here let's modify this one a little bit though we're going to modify this diagram a little bit to explain the somatotopic organization. So let's say here I draw another section here. Okay, now let's say first we come from the lumbar, right? Here's the lumbar region. These fibers are going to come in towards the midline, okay?
So they're going to come in towards that midline portion and then go up. Then over here you'll have Thoracic. These are going to come towards the midline region and go up.
And then you're going to have cervical and that's going to come towards the midline region and go up. And if you want you can even say sacral. That's going to be all the way here. Why am I telling you this? There's a way of being able to determine how this information is going up through the dorsal lumeniscus, sorry the dorsal column, sorry.
What would be right here? What would be towards the medial aspect? The most lower aspect of the limb.
So what would you have here? Towards the medial, this would be where the sacral region is. So the fibers coming from the sacral part of the spinal cord.
What would be next to it? There'd be lumbar. So lumbar is going to be a little bit more lateral. What's going to be even more lateral to that? The thoracic.
What's going to be even more lateral to that? The cervical. So the somatotopic arrangement here is really, truly important. You have to remember that.
That feeding in here, most medial, is the lower limbs. And as you go up, They just keep feeding in lateral to that. Why is that important?
If there's a lesion right here, it could affect the sacral and lumbar region, but not the thoracic and the cervical region. Or if there's a lesion more outside, more laterally, it could affect the cervical and thoracic and not the lumbar and the sacral. That's why it's so important to understand the somatotopic arrangement. One more thing that's important. If you notice, when these fibers are going into the actual spinal cord, do they cross?
Do they go to the contralateral side? No, they go to the ipsilateral. So, they stay on the same side of the spinal cord.
So, if we kind of make a section right here down the middle, this side, that side, they stay on the ipsilateral or the same side. That's really important. So, this pathway is ipsilateral at level of spinal cord.
Okay, that is super, super. Important. And it's important for clinical situations.
Okay? So now, we have the fasciculus cuneatus, we have the fasciculus gracilis. So we know our first order neuron, first order neuron was this point right here where the dorsal root ganglion is. Okay, so this is our first order neuron. So, or order, this is our first order neuron.
Now, how does this work? The first-order neuron, if you remember, this was the cell body, right? The pseudo-unipolar neuron. It has peripheral process going out to where the receptor is, picking up that sensation. Central process is going into the spinal cord.
And this is the axons of the first-order neuron, going up either as the vesiculus gracilis, below T6, vesiculus cuneatus, above T6. Now, where do these guys go? They go to a second-order neuron. And these second-order neurons are located within the medulla.
Kind of in the... posterior part of the medulla. These guys here are actually going to be a group of cell bodies within the CNS.
That's why they call them a nucleus. Now this one right here is the nucleus gracilis. And again over here on the right side is the nucleus gracilis. Over here this would be the nucleus cuneatus. And over here this would be the nucleus cuneatus.
So fasciculus cuneatus is gonna go where? It's gonna go here. And then what would you have over here?
You'd have the fasciculus gracilis synapsing where? On the nucleus gracilis and again on the same side. Now really fast here we go dorsal root ganglion here feeding in going up this is going to be coming up here more medial and where is this fasciculus gracilis here going to go?
It's going to go to the nucleus gracilis right? Same thing from the upper parts or above T6. What are you going to have? You're going to have the dorsal. Ganglion coming in here, funneling in where?
It's going to be funneling in a little bit more lateral. Moving up is the fasciculus cuneatus. Okay, so what do we have here collectively, guys?
We have the fasciculus cuneatus, which are the ones that are in red, and this is going to be the right fasciculus cuneatus. This is the left fasciculus cuneatus. Then what are these blue guys here called? These blue guys here are going to be called the fasciculus. gracilis, this is the right side, and this is the left fasciculus gracilis.
Okay? Now, as these guys synapse here on their second order neurons, so what are these guys here? These are the second order neurons, and again, where are they located?
At what part of the brainstem? This is the medulla oblongata, right? And this is the pons, and then midbrain here, and then you have your cerebral cortex up there, right? Now, from here something really interesting happens.
Remember I told you that it was ipsilateral at the entry of the spinal cord and as it's going up? Guess what? It changes now. As we get up here to the nucleus cuneatus and the nucleus gracilis, these guys form little connections. And what they do is, is they cross over to the opposite side.
So they kind of form like these little arc, right? So look at this, same thing here, same thing here. They're going to kind of cross over here to the opposite side.
What is this part here called where they cross and they go to the contralateral side? What are these called? That little crossing part there. That crossing part there is called the internal arcuate fibers. So this is called the internal arcuate fibers.
There's a reason why they call it internal. Because there is an external, and that's specifically for the cuneo-cerebellar tract, and we'll talk about that. Now, they cross over. Now, if they cross over, they cross in the dorsal part of the pons behind, actually, I'm sorry, they cross in the dorsal part of the medulla, just behind the pyramids, right?
And they move up through the medulla, through the pons, through the midbrain, as a special structure after they cross. What is this structure here called? This bundle here.
Well, It's called the medial leminiscus. And guess what? This is the left one. So what would this one be over here?
This would be the right one. So this one over here is going to be the right medial leminiscus. And this is going to move up through the brainstem.
As it moves up through the brainstem, it's going to converge on a specific nuclei located within the thalamus. Okay, so this is going to move upwards here as the medial lumeniscus, and it's going to synapse on a special nucleus located in the thalamus. What is this special nucleus here called? This nucleus is actually going to be called the ventral posterior lateral nucleus. Same thing over here, ventral posterior lateral nucleus.
There's another one called the ventral posterior medial, but... that's going to be picking up. There's actually another tract that kind of comes right with the medial limoniscus.
It's called the trigeminothalamic tract. It kind of comes upwards, but it goes to what's called the ventral posterior medial nucleus. We're not going to talk about that. But these medial limoniscus structures, they come upwards and they synapse on these third order neurons. Okay, so we're at third.
We hit second, which was the nucleus gracilis and cuneatus. We hit first, which was the dorsal reganglion. This is the next guy. So this is our third order neuron.
So this is our third. Order neuron, which is in the thalamus. It's the ventral posterior lateral nucleus of the thalamus.
From here, these fibers go to a specific part. They go here, you know this is the internal capsule, right here. And the internal capsule has like a posterior limb, and it has like this portion here called the genu, and then has the anterior limb. And then you have another structure if you want to know your neuroanatomy, you know that you have what's called the lentiform nucleus over here, which has the putamen, and then the globus pallidus internus externus.
and even have an external capsule and then you have what's called the colostrum right outside of that. What's really important here is this part here. You know we have the posterior limb. The posterior one-third right here of the internal capsule is where this nuclear, the ventral posterior lateral nucleus, has its axons move up through this, the posterior limb of the internal capsule. Now you're probably wondering, why is it that important to remember this?
There's a reason why it's important to remember this. There's arteries that supply... this structure here, the internal capsule.
And if at any situation there is an infarct in these arteries, you know there's what's called the lenticulostriate arteries, which are branches of the middle cerebral artery. The lenticulostriate arteries, if there's some type of infarction, it can affect the internal capsule. And that would affect the fibers that are going up through there, the sensory fibers.
So you might lose sensations, right? And that could be very, very bad. So again, what's gonna happen here? Metroposterior lateral nucleus moves up through the posterior limb. Again, what is this here?
Posterior, one-third limb of internal capsule, which is a projection fiber. And then it comes up through what's called the coronaradiata, and that is a radiating crown that's going to different parts of the cerebral cortex. But it's going to specifically one really important area.
Two important areas. You know, look, we have this diagram here. Let's pretend for a second I make this the central sulcus right here. There's a special gyrus which is located just posterior to the central sulcus. It's called the post-central gyrus, also called the primary somatosensory cortex.
There's another small one right behind it, which is called the secondary somatosensory cortex. We also kind of refer to this as, since this is primary somatosensory cortex, we call it S1. And since this is the secondary somatosensory cortex, we call it S2. It's mainly going to these areas.
But there's an importance to this. So again, it's going mainly to these areas out here. Now let's assume that this is the primary somatosensory cortex and the secondary somatosensory cortex. Same thing over here. Ventral posterior lateral nucleus goes to the internal capsule.
Posterior limb of it, posterior one-third. and this gets sent out through coronaradiata to different parts of the cerebral cortex. There's an important thing for this. We need to talk about this.
Let me come over here real quick. Let me draw a small little diagram. It doesn't have to be anything important, but I just want us to get this part here. So what I'm doing here is I'm just drawing kind of a small section here of the actual parietal lobe. Okay, small section, nothing crazy here.
Let's just imagine there's a small section of the parietal lobe. Our parietal lobe is arranged in such a way, in such a way, that certain sensations go to specific areas of the actual primary and secondary somatosensory cortex. Primarily the primary though.
And how does it work? For example, let's say here, right here, right? Where we're talking about that, where the central sulcus is, or you have this point right here.
Let's say this is a longitudinal fissure. Right here you have what's called your external genitalia. Any sensations from the external genitalia can be sensed right here at that point. Right there at that point right there.
If we go up, maybe we have the foot. The foot can be felt at that point right there. Go up even more. Maybe the leg. Then the hip.
Then the trunk of the body. Then maybe the neck. Then as you keep going, maybe you actually have what else?
You have the arm. You have the hand. The thumb. And as you keep going, you have your face. You might even have the tongue, the pharynx, and even intra-abdominal.
There's a specific somatotopy. Okay, so this is the somatotopic organization. Sometimes you might see this in textbooks as like a little man.
You know, little man is actually referred to as a homunculus. So this is our sensory homunculus. So when information is going up, imagine right here is where the thalamus is, right here.
Imagine right here is where the thalamus is. Okay? From here, any fibers that are coming up and going to specific parts of the cerebral cortex are going to a specific area that is associated with sensations to that specific location of the body.
So, if someone kicks you in the nuts, It's going to be going right here to this part of the primary somatosensory cortex. If someone steps on your foot, it'll go here. You get the point that there's a somatotopic organization of the actual postcentral gyrus. All right, so we covered this in pretty good detail. Now, one last thing I wanted to talk about.
This internal capsule, you know it's a specific type of fibers? This internal capsule is actually referred to as what's called a projection fiber. Okay, and projection fibers are important because they allow for information to kind of go up and down. So that's what's really important.
This internal capsule and another structure called the coronaradiata are projection fibers. They're a bundle of white matter. So in a way, they're kind of like a tract, but they're different.
Again, they're actually going to be taking this information upwards, and they can take information downwards via through motor pathways, the corticospinal tracts, which we'll talk about in another video. So that's really important. Last thing is you also have other structures here like commissural. And commissural fibers are important, like for example the corpus callosum. They allow for information to go from right cerebral hemisphere to left cerebral hemisphere, right?
And that's an example of the corpus callosum. Another one is called association fibers. And association fibers are important because they allow for information to go front, so let's say anterior, to posterior, right? Or posterior to anterior, either way. And these are like an example of this one is like the arcuate fasciculus which connects the Wernicke's to the Broca's.
So there's different types of structures, different white matter fibers, which are going to be in the central nervous system that are super, super important. And I just want to, I thought I'd take a little bit of time to mention that real quick. All right, NinjaNerds, so I hope all of this made sense. I really hope that you guys did enjoy it. If you guys did like the video, please hit that like button, comment down in the comment section, and please subscribe.
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