Ascending Tracts | Spinocerebellar Tract

Alright Ninja Nerds, in this video we're going to talk about the Spinoserebellar Tracts. So again, if you guys haven't already, please go watch the dorsal column, medial and meniscal pathway first. Then after that, go watch the spinothalamic pathway. After that, watch the pain modulation video. Now the last one we're going to talk about is the Spinoserebellar Tracts. So let's go ahead and get started on that. So Spinoserebellar Tracts, as they say, they're going from whatever receptor, which we'll talk about, into the spinal cord. up to the cerebellum and most pretty much all of them are ipsilateral. Okay so now what are some of these spinocerebellar tracts? Okay so let's talk about these ones. So the first one we're going to talk about is going to be what's called the dorsal spino. cerebellar tract. We're actually going to kind of write this down you might see me write it as DST dorsal spinal cerebellar tract. Another one is going to be called the ventral spinal cerebellar tract and again you might see me be a little lazy bugger and write that as VST. And we'll talk about one more, okay, which is really important. And this guy is called the cuneocerebellar tract, okay? And just because I'm lazy, I'm going to put CT. All right, so these guys are really important, okay? And we're going to talk about these in pretty good detail and talk about their stimulus. We'll talk about their receptor. We'll talk about where they're going to in the spinal cord and where they ascend to and where they terminate. So let's go ahead and start off with the dorsal spinocerebellar tract first. And we'll also just to throw this one in there at the end, we'll do one last tract and that is actually going to be called the spino olivary tract. We'll throw this one in there at the end because it's related to the cerebellum. Okay, it goes to the olives first, the inferior olives, and then it goes to the cerebellum. So we'll discuss this one last. Okay? Alright, so let's go ahead and get started on the dorsal spinocerebellar tract. So again, we know that these tracts, what is a tract? It's a bundle of white matter, axons basically, that are moving in the central nervous system. And these are ascending tracts. Okay? So because they're going from the spinal cord to the cerebellum. Now... What is the actual stimulus for these tracts? Pretty much all of these tracts, to make it easy on yourself, pretty much all of the spinocerebellar tracts respond to proprioception. Okay? So pretty much all of these tracts respond to proprioception. So what is this proprioception? Proprioception, we've talked about this in the dorsal column pathway, but proprioception is really important. It's basically... The sensation, in this case since it's the cerebellum, it's the unconscious awareness of one's position of their limbs or their trunk in space. So in other words, how do I describe that? I know where my arm is, right, in space. I know where my finger is. I know it's touching my nose. I know it's touching my eyes. In another way, these proprioceptors, not only are they going up through the dorsal column, right, that tract. But some of them are actually terminating in the cerebellum. So now, this information is going to go to the cerebellum. Now, the cerebellum is important, right? Because the cerebellum controls posture, it controls balance, it controls muscle tone and coordination of muscle movements. Now, how does it do that, though? How does it maintain our posture? How does it coordinate these muscle movements? Help us to have very precise muscle movements. How? Well, the way it does that, it has to be able to get incoming sensations from our periphery. It also has to consult with our cerebral cortex. And so by doing that, it can allow for it to really calculate an accurate movement. That's why the cerebellum is so important that it needs to constantly be getting information from our proprioceptors. That is the primary important one. But it can receive some other sensations from exteroreceptors like touch and pressure receptors. But I want you to remember the main stimulus is proprioception. And where is that proprioception? interception coming from. Remember we have those muscle spindles, right? So we have those muscle, muscle spindles. Remember the muscle spindles, you have the two parts, you have the nuclear bag fibers and nuclear chain fibers, right? And the nuclear chain fibers were responding to specifically what they were responding to. The beginning of stretch nuclear bag was responding to the progression of stretch. Then we also had some other structures here, which was the Golgi tendon organ. And these are responding to the stretch of the tendons. Now, I did say that you can also not only respond to proprioception, but also touch and pressure. Okay? So this is important. It's not as significant as the proprioception, but it can have some unconscious sensations that it can pick up, like touch and pressure. So it can pick up information from like your Meissner's corpuscles. Okay, it can pick it up from the Pacinian corpuscles, maybe from the Ruffinian corpuscles. All right, so different types of receptors, different types of touch and pressure receptors. Now, as this information comes together, so we'll have touch and pressure receptors, we'll have this proprioception. All this information is going to go into the spinal cord. So let's come down to the bottom part of the spinal cord. Okay, now from here, what do you have here? You have the dorsal root ganglion, right? So you have the dorsal root ganglion here. This is where the first order neuron is. So again, dorsal root ganglion is where the first order neuron of this pathway is, the dorsal spinocerebellar tract. From here, the peripheral process is picking up the proprioception, the touch, and the pressure, transmitting it down to the pseudounipolar neuron. and into the central process. Where does it go from here? Now there's a specific nucleus that this is gonna stop on. Okay, it's a very specific one. So this is again, we're talking about the dorsal spinocerebellar tract. So this right here, that nucleus is a very specific nucleus. Okay, and we're gonna talk about that now because we have to understand this first. Okay, so let's let's let me explain how this works, this dorsal spinocerebellar tract, because it's important. So imagine here, I take a part of the spinal cord here, right? And let's say that this is like the midline region, okay? And then this is right side, this is left side. There's a set of nuclei located within the actual posterior grey horn, a certain length of segments in the spinal cord. So you're going to find these nuclei. They're actually located within the Rex Lamina 7, if you want to know. And these nuclei extend from C8 all the way to L2, maybe even L3. So because of that, these nucleus, they make a column, if you will, right? So what is this column? They call this Clark's column. And it extends from C8 all the way down to about L3. And that is that second order neuron for the dorsal spinocerebellar tract. So that's really important. So what is this nucleus right there? That nucleus is Clark's nucleus. It's a part of Clark's column. Where does it go from here? Okay, so now from here, from this Clark's nucleus, which is extending from C8 all the way down to L2, L3, it's going to come over here into the lateral white column. So over here, all this area right here is lateral white column. It's going to go more in the posterior or dorsal part of the actual lateral Y column. And then guess what? It's going to ascend. So now we're going to have this sucker moving upwards here. So now we should understand here how this works. First order neuron is within the dorsal root ganglion. Second order neuron extends from C8. to L2, L3 and that is going to be Clark's nucleus which is actually going to be here within lamina, rex lamina if you will, rex lamina 7 and then again from here it's going to it's actually going to move ipsilateral within the posterior or dorsal part of the lateral white column and then ascend upwards. Now from here where is it going to go? You know there's a special type of white matter. Fiber right here, and this is medulla, pons, midbrain, cerebellum. What happens is... There's an actual white matter structure here where these fibers can actually pass through and then go and supply the cerebro cortex. I'm sorry, not cerebro cortex, cerebellar cortex. This structure right here that it's actually moving through is called the inferior cerebellar peduncles. Okay. So again, what is this tract right here called? This tract is called the dorsal spinocerebellar tract. Okay? It's our DST we're calling it here. All right. We got that sucker down. Okay. Now, let me bring him a little bit more posterior since we said he was posterior. So that's a little better. I like that now. Alright, cool. So we got the dorsal spinal cerebellar tract, which again is extending from C3, I'm sorry, C8 all the way down to L3. And what type of sensations is it picking up? Touch, pressure, proprioception. Sweet deal. The third order neuron is going to be the cerebellar cortex. So again, you'll have some nuclei out here that it can actually go to. And again, that is going to be the cerebellar cortex. That's its final termination site. Okay, so we covered the dorsal. Spinoserebellar tract. Well now we need to do the next one, which is the ventral spinoserebellar tract. This one's kind of a tricky one. So this one's picking up information from below L3. So any structures that are coming from below L3, so from L3, L2, L3, all the way down to the coccygeal, to the coccygeal one, right? All this part down here, is going to be carried by the ventral spinocerebellar tract. So again, from L2, L3 below is going to be carried by the ventral spinocerebellar tract. Okay, so let's go ahead and zoom in on that one now. So, since this one's a tricky one, I want to show you guys this one. It's very interesting. Let me actually get this out of the way here. Let me put this right here. This is our dorsal spinocerebellar tract. Okay, this one's very cool. I like this one a lot. Let's say we come from here, same thing. It's also going to be carrying information of proprioception. It's going to be carrying touch and pressure, but it's going to be carrying it from information below L2, L3. This guy, again, he'll go to what's called the dorsal root ganglion, right? In the dorsal root ganglion, you're going to have this pseudo unipolar neuron. That is going to be the first Order, enter on. From here, he's going to come into the actual dorsal gray horn and synapse on cell bodies within the dorsal gray horn. From here, here's where it gets tricky. He crosses over to the opposite side, to the contralateral side, and then ascends upward. So what do we have here for the ventral spinal cerebellar tract? So again, this one right here is the ventral spinal cerebellar tract. First order neuron is actually going to be in the dorsal root ganglion. Second order neuron is going to be within the posterior or dorsal gray horn. Then it crosses, so it goes across the midline via the anterior white commissure and crosses over to the contralateral side of the spinal cord and ascends upward. Now, as it goes upwards, It goes all the way up here. So now this tract, it goes in to where the midbrain is and goes through this white matter structure. Now what is this sucker called? Well let's look. This was the inferior cerebellar peduncles connecting the medulla to the cerebellum. This is the middle cerebellar peduncles connecting the pons to the cerebellum. So this one's got to be the superior. So this one right here is called the superior cerebellar peduncles. Now, Now, from this, here's why I told you, it's a tricky track, right? Look what it does. This guy is really sneaky. He moves behind. So you know there's the two cerebellum, right? This guy moves from one side of the cerebellum. So let's say that this, in this case, this is the left cerebellum. This is the right cerebellum. He moves behind this structure into the opposite side. So look here, I'll draw like kind of like a dash line here. It's going behind. and it's going to the other cerebellum, so it crosses twice. And then from here, it synapses on the third-order neurons of the cerebellar cortex. So that's what's really important. So the ventral spinal cerebellar tract, the only difference is from the dorsal, because if they both carry proprioception, touch, and some pressure. The only difference is that the dorsal comes in, crosses over ipsilateral to the lateral white column, and ascends upward. And then it goes to the inferior cerebellar peduncles, to the actual cerebellum. The ventral is actually going to come in, cross, ascend, go in, and cross again. Now, why did I say, now if you look here, let's pretend for a second I have this guy come right here. So I just want you to understand why they say that this is dorsal, the pink pathway here. Comes in, synapses, and then look where it goes. It goes here and comes up. Okay? So this is going to be the posterior part of the lateral white column. This is the anterior part of the lateral white column. Or, to say it a different way, this is the dorsal part of the lateral white column. This is the ventral part of the lateral white column. So that's why they call this tract going upwards, the blue tract, the ventral spinocerebellar tract. That's why they call this pink one because it's more dorsal to it. That's why they call it the dorsal spinocerebellar tract. Okay, so I just wanted to make sure that we're clear on that. Okay, sweet deal. So we've done the ventral spinocerebellar tract. We've done the dorsal spinocerebellar tract. Now it's time to do the cuneocerebellar tract. Well, it's so easy since we set this establishment down. For the dorsal spinocerebellar, that from C8 to L2, L3 is the dorsal spinocerebellar tract. Below L2, L3 is the ventral spinocerebellar tract. What do you think is above the cuneocerebellar tract? So now it's not so hard to understand that anything above C8 up to C1 should now be the cuneocerebellar tract. So this is mainly picking up proprioception, touch and pressure from the upper limbs and the actual head and neck structures. So that should make sense. So now how does that work? Okay, let's actually show this guy now. Let's do that here. We'll come at this level. Actually no, we'll come up, yeah, we'll come up at this level. So here we're gonna have this guy coming in here. Actually, there's more room here. Let's do it here. So here is going to be this guy, right? Again, this is going to be the peripheral process. It's going to be picking up touch, pressure, proprioception from like the head, the neck, the upper limb structures. And then what? It's going to send its central process in. From here, when it goes into the central process, it goes into the posterior gray horn, right? It goes into the posterior gray horn. And then it actually moves upwards, ipsilaterally, right? So it moves upwards, and as it moves upwards, it comes to a special nucleus, okay? It comes to a special nucleus here that is actually located within the medulla. This nucleus is really interesting because it's going to sound familiar. It's going to sound very, very familiar. This... Nucleus is called the accessory cuneate nucleus. You're probably like, wait a second, I've heard of that before. Nucleus cuneatus. Well, that was for the dorsal column medial liminiscal pathway. Here's the thing. With the cuneocerebellar tract, they're not sure yet if it actually moves up with the fasciculus cuneatus or not. But they know that it actually ascends and moves ipsilaterally. and picks up sensations from anything above C8, the head and the neck and the upper limbs. They just know that it ascends upwards and it synapses on this structure here located within the medulla called the accessory or the external cuneate nucleus. Then where does it go? Remember here, just for simplicity's sake here, you had the nucleus cuneatus, nucleus gracilis, nucleus gracilis, and then nucleus cuneatus, right? They got... synapses from the dorsal column and then they crossed over, right? And when they crossed over, we called that cross the internal arcuate fibers, right? They call that cross of the internal arcuate fibers. Well, guess what? This accessory cuneate nucleus gives off fibers that move through the inferior cerebellar peduncles. They call these fibers that are coming from the accessory cuneate nucleus the external arcuate fibers. So beautiful. So this is called the external arcuate fibers. Now from here, where will it go? It'll go through the inferior cerebellar peduncles, and it'll go and supply parts of the cerebellar cortex. So again, just remember that this cuneocerebellar tract, let's actually put this a little bit more over here. They're not sure if it moves up, but they think that it might move up through the fasciculus cuneatus. But instead of it actually synapsing at the nucleus cuneatus, It actually synapses at a different portion here, and that is called the accessory or the external cuneate nucleus. And then from there, fibers will come to the cerebellum through the inferior cerebellar peduncles. And these fibers that are going to go into the inferior cerebellar peduncles is called the external arcuate fibers. Okay, so that covers that, guys. Now, last part. I said that we were going to do a little tidbit on the spinal olivary tract. This one is important too. There's special nuclei located within the medulla. And these nuclei here are called the inferior olivary nuclei. So these are called your inferior olivary nuclei. These guys right here. This system is a little bit odd. It's another little tricky tract. Okay, how does this one work? Okay, let's actually do this one in green, since we have this in green. So this tract is a little interesting. So it's going to be picking up a bunch of different proprioception, a bunch of different touch, a bunch of different pressure. How does this tract work? Okay, so let's say here we have this guy coming in. Again, this is going to be the peripheral process picking up touch, pressure, proprioception, and then this is going to be the central process, which is going to be going into the dorsal. I'm going to come down a little bit farther here. In the dorsal rugangula, it's going to synapse on a second-order neuron. So here's our second-order neuron. From here, it's going to cross over. It's going to cross over to the contralateral side through the anterior white commissure and then move upwards. Now, as this tract moves upwards, it comes and it synapses. on this nucleus right here, this inferior olivary nucleus. Now, from the inferior olivary nucleus, something tricky happens. So again, what happens here, these fibers are coming in, dorsal root ganglion, into the posterior grey horn, synapsing on the cell bodies there, crossing to the contralateral side, ascending upwards as the spinal olivary tract. As it goes upwards, it synapses on the inferior olivary nucleus. From the inferior olivary nucleus, these fibers cross the midline. So they cross the midline and go over to the other side and then enter into the actual cerebellum through what's called the inferior cerebellar peduncles. Okay, so same thing if we were having it come up here. They're on the opposite side. What would it do? It would cross over here. and then move into the inferior cerebellar peduncles and then supply the cerebellar cortex. There's a reason why we should mention these. Any fibers that are coming from the inferior olivary nucleus going into the cerebellum have a specific type of name. These fibers, these green fibers, if they're coming from the inferior olivary nucleus, they call these climbing fibers. They call them climbing fibers. Any other fiber, any other fiber which is coming from the ventral spinal cerebellar tract, the dorsal spinal cerebellar tract, the cuneo cerebellar tract, any of that information that's going into the cerebellum besides the inferior olivary nucleus, for example, this pink fiber here. This pink fiber was coming from the dorsal spinal cerebellar tract. Any fibers. other than the climbing fibers which are coming from the inferior olivary nucleus are referred to as mossy fibers, okay? They're called mossy fibers. So there's two different types of fibers, climbing fibers which are coming from the inferior olivary nucleus and mossy fibers which are coming from anywhere, any other fibers, okay? Whether it be dorsal spinocerebellar, ventral spinocerebellar, or cuneo spinocerebellar, I'm sorry, cuneo cerebellar tract, okay? And where was the cuneo cerebellar just so we can have that here? So we can have it all marked down. It was this guy right here. So this guy right here was our cuneo cerebellar tract. And then the last one was this green one here. And this green one was the spino olivary tract. Alright Ningeners, so that pretty much covers everything that you guys would need to know about the Spino Cerebellar Tracks. I hope it all made sense. I really, truly do, guys. I hope you guys enjoyed it. If you guys did, please hit that like button. Comment down in the comments section. Please subscribe, guys. Also, if you guys have the time, please go check out our Facebook account or Instagram. Maybe leave some comments, like some pictures there. Also, if you do have the opportunity, maybe even check our Patreon out. If you guys have the opportunity to donate, we'd truly appreciate it. It would make the difference in helping us to make the most high quality videos for you guys' enjoyment. Alright, Ningeners, as always, until next time.

After that, watch the pain modulation video. Now the last one we're going to talk about is the Spinoserebellar Tracts. So let's go ahead and get started on that.

So Spinoserebellar Tracts, as they say, they're going from whatever receptor, which we'll talk about, into the spinal cord. up to the cerebellum and most pretty much all of them are ipsilateral. Okay so now what are some of these spinocerebellar tracts? Okay so let's talk about these ones.

So the first one we're going to talk about is going to be what's called the dorsal spino. cerebellar tract. We're actually going to kind of write this down you might see me write it as DST dorsal spinal cerebellar tract.

Another one is going to be called the ventral spinal cerebellar tract and again you might see me be a little lazy bugger and write that as VST. And we'll talk about one more, okay, which is really important. And this guy is called the cuneocerebellar tract, okay?

And just because I'm lazy, I'm going to put CT. All right, so these guys are really important, okay? And we're going to talk about these in pretty good detail and talk about their stimulus.

We'll talk about their receptor. We'll talk about where they're going to in the spinal cord and where they ascend to and where they terminate. So let's go ahead and start off with the dorsal spinocerebellar tract first.

And we'll also just to throw this one in there at the end, we'll do one last tract and that is actually going to be called the spino olivary tract. We'll throw this one in there at the end because it's related to the cerebellum. Okay, it goes to the olives first, the inferior olives, and then it goes to the cerebellum.

So we'll discuss this one last. Okay? Alright, so let's go ahead and get started on the dorsal spinocerebellar tract.

So again, we know that these tracts, what is a tract? It's a bundle of white matter, axons basically, that are moving in the central nervous system. And these are ascending tracts.

Okay? So because they're going from the spinal cord to the cerebellum. Now...

What is the actual stimulus for these tracts? Pretty much all of these tracts, to make it easy on yourself, pretty much all of the spinocerebellar tracts respond to proprioception. Okay?

So pretty much all of these tracts respond to proprioception. So what is this proprioception? Proprioception, we've talked about this in the dorsal column pathway, but proprioception is really important.

It's basically... The sensation, in this case since it's the cerebellum, it's the unconscious awareness of one's position of their limbs or their trunk in space. So in other words, how do I describe that? I know where my arm is, right, in space.

I know where my finger is. I know it's touching my nose. I know it's touching my eyes. In another way, these proprioceptors, not only are they going up through the dorsal column, right, that tract.

But some of them are actually terminating in the cerebellum. So now, this information is going to go to the cerebellum. Now, the cerebellum is important, right? Because the cerebellum controls posture, it controls balance, it controls muscle tone and coordination of muscle movements.

Now, how does it do that, though? How does it maintain our posture? How does it coordinate these muscle movements? Help us to have very precise muscle movements.

How? Well, the way it does that, it has to be able to get incoming sensations from our periphery. It also has to consult with our cerebral cortex. And so by doing that, it can allow for it to really calculate an accurate movement. That's why the cerebellum is so important that it needs to constantly be getting information from our proprioceptors.

That is the primary important one. But it can receive some other sensations from exteroreceptors like touch and pressure receptors. But I want you to remember the main stimulus is proprioception.

And where is that proprioception? interception coming from. Remember we have those muscle spindles, right?

So we have those muscle, muscle spindles. Remember the muscle spindles, you have the two parts, you have the nuclear bag fibers and nuclear chain fibers, right? And the nuclear chain fibers were responding to specifically what they were responding to.

The beginning of stretch nuclear bag was responding to the progression of stretch. Then we also had some other structures here, which was the Golgi tendon organ. And these are responding to the stretch of the tendons. Now, I did say that you can also not only respond to proprioception, but also touch and pressure.

Okay? So this is important. It's not as significant as the proprioception, but it can have some unconscious sensations that it can pick up, like touch and pressure.

So it can pick up information from like your Meissner's corpuscles. Okay, it can pick it up from the Pacinian corpuscles, maybe from the Ruffinian corpuscles. All right, so different types of receptors, different types of touch and pressure receptors. Now, as this information comes together, so we'll have touch and pressure receptors, we'll have this proprioception. All this information is going to go into the spinal cord.

So let's come down to the bottom part of the spinal cord. Okay, now from here, what do you have here? You have the dorsal root ganglion, right? So you have the dorsal root ganglion here.

This is where the first order neuron is. So again, dorsal root ganglion is where the first order neuron of this pathway is, the dorsal spinocerebellar tract. From here, the peripheral process is picking up the proprioception, the touch, and the pressure, transmitting it down to the pseudounipolar neuron. and into the central process.

Where does it go from here? Now there's a specific nucleus that this is gonna stop on. Okay, it's a very specific one. So this is again, we're talking about the dorsal spinocerebellar tract. So this right here, that nucleus is a very specific nucleus.

Okay, and we're gonna talk about that now because we have to understand this first. Okay, so let's let's let me explain how this works, this dorsal spinocerebellar tract, because it's important. So imagine here, I take a part of the spinal cord here, right? And let's say that this is like the midline region, okay? And then this is right side, this is left side.

There's a set of nuclei located within the actual posterior grey horn, a certain length of segments in the spinal cord. So you're going to find these nuclei. They're actually located within the Rex Lamina 7, if you want to know. And these nuclei extend from C8 all the way to L2, maybe even L3.

So because of that, these nucleus, they make a column, if you will, right? So what is this column? They call this Clark's column. And it extends from C8 all the way down to about L3. And that is that second order neuron for the dorsal spinocerebellar tract.

So that's really important. So what is this nucleus right there? That nucleus is Clark's nucleus. It's a part of Clark's column.

Where does it go from here? Okay, so now from here, from this Clark's nucleus, which is extending from C8 all the way down to L2, L3, it's going to come over here into the lateral white column. So over here, all this area right here is lateral white column.

It's going to go more in the posterior or dorsal part of the actual lateral Y column. And then guess what? It's going to ascend.

So now we're going to have this sucker moving upwards here. So now we should understand here how this works. First order neuron is within the dorsal root ganglion.

Second order neuron extends from C8. to L2, L3 and that is going to be Clark's nucleus which is actually going to be here within lamina, rex lamina if you will, rex lamina 7 and then again from here it's going to it's actually going to move ipsilateral within the posterior or dorsal part of the lateral white column and then ascend upwards. Now from here where is it going to go?

You know there's a special type of white matter. Fiber right here, and this is medulla, pons, midbrain, cerebellum. What happens is... There's an actual white matter structure here where these fibers can actually pass through and then go and supply the cerebro cortex.

I'm sorry, not cerebro cortex, cerebellar cortex. This structure right here that it's actually moving through is called the inferior cerebellar peduncles. Okay.

So again, what is this tract right here called? This tract is called the dorsal spinocerebellar tract. Okay?

It's our DST we're calling it here. All right. We got that sucker down.

Okay. Now, let me bring him a little bit more posterior since we said he was posterior. So that's a little better.

I like that now. Alright, cool. So we got the dorsal spinal cerebellar tract, which again is extending from C3, I'm sorry, C8 all the way down to L3. And what type of sensations is it picking up?

Touch, pressure, proprioception. Sweet deal. The third order neuron is going to be the cerebellar cortex. So again, you'll have some nuclei out here that it can actually go to.

And again, that is going to be the cerebellar cortex. That's its final termination site. Okay, so we covered the dorsal. Spinoserebellar tract. Well now we need to do the next one, which is the ventral spinoserebellar tract.

This one's kind of a tricky one. So this one's picking up information from below L3. So any structures that are coming from below L3, so from L3, L2, L3, all the way down to the coccygeal, to the coccygeal one, right?

All this part down here, is going to be carried by the ventral spinocerebellar tract. So again, from L2, L3 below is going to be carried by the ventral spinocerebellar tract. Okay, so let's go ahead and zoom in on that one now.

So, since this one's a tricky one, I want to show you guys this one. It's very interesting. Let me actually get this out of the way here.

Let me put this right here. This is our dorsal spinocerebellar tract. Okay, this one's very cool.

I like this one a lot. Let's say we come from here, same thing. It's also going to be carrying information of proprioception. It's going to be carrying touch and pressure, but it's going to be carrying it from information below L2, L3.

This guy, again, he'll go to what's called the dorsal root ganglion, right? In the dorsal root ganglion, you're going to have this pseudo unipolar neuron. That is going to be the first Order, enter on.

From here, he's going to come into the actual dorsal gray horn and synapse on cell bodies within the dorsal gray horn. From here, here's where it gets tricky. He crosses over to the opposite side, to the contralateral side, and then ascends upward. So what do we have here for the ventral spinal cerebellar tract?

So again, this one right here is the ventral spinal cerebellar tract. First order neuron is actually going to be in the dorsal root ganglion. Second order neuron is going to be within the posterior or dorsal gray horn. Then it crosses, so it goes across the midline via the anterior white commissure and crosses over to the contralateral side of the spinal cord and ascends upward.

Now, as it goes upwards, It goes all the way up here. So now this tract, it goes in to where the midbrain is and goes through this white matter structure. Now what is this sucker called? Well let's look. This was the inferior cerebellar peduncles connecting the medulla to the cerebellum.

This is the middle cerebellar peduncles connecting the pons to the cerebellum. So this one's got to be the superior. So this one right here is called the superior cerebellar peduncles.

Now, Now, from this, here's why I told you, it's a tricky track, right? Look what it does. This guy is really sneaky.

He moves behind. So you know there's the two cerebellum, right? This guy moves from one side of the cerebellum. So let's say that this, in this case, this is the left cerebellum. This is the right cerebellum.

He moves behind this structure into the opposite side. So look here, I'll draw like kind of like a dash line here. It's going behind. and it's going to the other cerebellum, so it crosses twice.

And then from here, it synapses on the third-order neurons of the cerebellar cortex. So that's what's really important. So the ventral spinal cerebellar tract, the only difference is from the dorsal, because if they both carry proprioception, touch, and some pressure. The only difference is that the dorsal comes in, crosses over ipsilateral to the lateral white column, and ascends upward.

And then it goes to the inferior cerebellar peduncles, to the actual cerebellum. The ventral is actually going to come in, cross, ascend, go in, and cross again. Now, why did I say, now if you look here, let's pretend for a second I have this guy come right here. So I just want you to understand why they say that this is dorsal, the pink pathway here. Comes in, synapses, and then look where it goes.

It goes here and comes up. Okay? So this is going to be the posterior part of the lateral white column.

This is the anterior part of the lateral white column. Or, to say it a different way, this is the dorsal part of the lateral white column. This is the ventral part of the lateral white column.

So that's why they call this tract going upwards, the blue tract, the ventral spinocerebellar tract. That's why they call this pink one because it's more dorsal to it. That's why they call it the dorsal spinocerebellar tract. Okay, so I just wanted to make sure that we're clear on that. Okay, sweet deal.

So we've done the ventral spinocerebellar tract. We've done the dorsal spinocerebellar tract. Now it's time to do the cuneocerebellar tract.

Well, it's so easy since we set this establishment down. For the dorsal spinocerebellar, that from C8 to L2, L3 is the dorsal spinocerebellar tract. Below L2, L3 is the ventral spinocerebellar tract.

What do you think is above the cuneocerebellar tract? So now it's not so hard to understand that anything above C8 up to C1 should now be the cuneocerebellar tract. So this is mainly picking up proprioception, touch and pressure from the upper limbs and the actual head and neck structures.

So that should make sense. So now how does that work? Okay, let's actually show this guy now. Let's do that here.

We'll come at this level. Actually no, we'll come up, yeah, we'll come up at this level. So here we're gonna have this guy coming in here. Actually, there's more room here. Let's do it here.

So here is going to be this guy, right? Again, this is going to be the peripheral process. It's going to be picking up touch, pressure, proprioception from like the head, the neck, the upper limb structures. And then what? It's going to send its central process in.

From here, when it goes into the central process, it goes into the posterior gray horn, right? It goes into the posterior gray horn. And then it actually moves upwards, ipsilaterally, right?

So it moves upwards, and as it moves upwards, it comes to a special nucleus, okay? It comes to a special nucleus here that is actually located within the medulla. This nucleus is really interesting because it's going to sound familiar.

It's going to sound very, very familiar. This... Nucleus is called the accessory cuneate nucleus.

You're probably like, wait a second, I've heard of that before. Nucleus cuneatus. Well, that was for the dorsal column medial liminiscal pathway. Here's the thing. With the cuneocerebellar tract, they're not sure yet if it actually moves up with the fasciculus cuneatus or not.

But they know that it actually ascends and moves ipsilaterally. and picks up sensations from anything above C8, the head and the neck and the upper limbs. They just know that it ascends upwards and it synapses on this structure here located within the medulla called the accessory or the external cuneate nucleus.

Then where does it go? Remember here, just for simplicity's sake here, you had the nucleus cuneatus, nucleus gracilis, nucleus gracilis, and then nucleus cuneatus, right? They got...

synapses from the dorsal column and then they crossed over, right? And when they crossed over, we called that cross the internal arcuate fibers, right? They call that cross of the internal arcuate fibers.

Well, guess what? This accessory cuneate nucleus gives off fibers that move through the inferior cerebellar peduncles. They call these fibers that are coming from the accessory cuneate nucleus the external arcuate fibers. So beautiful.

So this is called the external arcuate fibers. Now from here, where will it go? It'll go through the inferior cerebellar peduncles, and it'll go and supply parts of the cerebellar cortex. So again, just remember that this cuneocerebellar tract, let's actually put this a little bit more over here.

They're not sure if it moves up, but they think that it might move up through the fasciculus cuneatus. But instead of it actually synapsing at the nucleus cuneatus, It actually synapses at a different portion here, and that is called the accessory or the external cuneate nucleus. And then from there, fibers will come to the cerebellum through the inferior cerebellar peduncles.

And these fibers that are going to go into the inferior cerebellar peduncles is called the external arcuate fibers. Okay, so that covers that, guys. Now, last part. I said that we were going to do a little tidbit on the spinal olivary tract.

This one is important too. There's special nuclei located within the medulla. And these nuclei here are called the inferior olivary nuclei. So these are called your inferior olivary nuclei.

These guys right here. This system is a little bit odd. It's another little tricky tract. Okay, how does this one work?

Okay, let's actually do this one in green, since we have this in green. So this tract is a little interesting. So it's going to be picking up a bunch of different proprioception, a bunch of different touch, a bunch of different pressure.

How does this tract work? Okay, so let's say here we have this guy coming in. Again, this is going to be the peripheral process picking up touch, pressure, proprioception, and then this is going to be the central process, which is going to be going into the dorsal.

I'm going to come down a little bit farther here. In the dorsal rugangula, it's going to synapse on a second-order neuron. So here's our second-order neuron.

From here, it's going to cross over. It's going to cross over to the contralateral side through the anterior white commissure and then move upwards. Now, as this tract moves upwards, it comes and it synapses. on this nucleus right here, this inferior olivary nucleus. Now, from the inferior olivary nucleus, something tricky happens.

So again, what happens here, these fibers are coming in, dorsal root ganglion, into the posterior grey horn, synapsing on the cell bodies there, crossing to the contralateral side, ascending upwards as the spinal olivary tract. As it goes upwards, it synapses on the inferior olivary nucleus. From the inferior olivary nucleus, these fibers cross the midline.

So they cross the midline and go over to the other side and then enter into the actual cerebellum through what's called the inferior cerebellar peduncles. Okay, so same thing if we were having it come up here. They're on the opposite side.

What would it do? It would cross over here. and then move into the inferior cerebellar peduncles and then supply the cerebellar cortex.

There's a reason why we should mention these. Any fibers that are coming from the inferior olivary nucleus going into the cerebellum have a specific type of name. These fibers, these green fibers, if they're coming from the inferior olivary nucleus, they call these climbing fibers.

They call them climbing fibers. Any other fiber, any other fiber which is coming from the ventral spinal cerebellar tract, the dorsal spinal cerebellar tract, the cuneo cerebellar tract, any of that information that's going into the cerebellum besides the inferior olivary nucleus, for example, this pink fiber here. This pink fiber was coming from the dorsal spinal cerebellar tract. Any fibers.

other than the climbing fibers which are coming from the inferior olivary nucleus are referred to as mossy fibers, okay? They're called mossy fibers. So there's two different types of fibers, climbing fibers which are coming from the inferior olivary nucleus and mossy fibers which are coming from anywhere, any other fibers, okay?

Whether it be dorsal spinocerebellar, ventral spinocerebellar, or cuneo spinocerebellar, I'm sorry, cuneo cerebellar tract, okay? And where was the cuneo cerebellar just so we can have that here? So we can have it all marked down.

It was this guy right here. So this guy right here was our cuneo cerebellar tract. And then the last one was this green one here. And this green one was the spino olivary tract. Alright Ningeners, so that pretty much covers everything that you guys would need to know about the Spino Cerebellar Tracks.

I hope it all made sense. I really, truly do, guys. I hope you guys enjoyed it.

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Transcript for:Ascending Tracts | Spinocerebellar Tract

Transcript for:
Ascending Tracts | Spinocerebellar Tract