Week 1 Motor Cortices & Cerebellum Flashcards
What is coordination? Control of movement?
When we talk about movement control and movement coordination, or motor control and motor coordination, we’re talking about two very specific things. When we talk about (coordination of movement/control of movement), we’re talking about creating the plan, initiating the plan, and then executing the plan. So the idea of creating a movement. And in order for movement control to happen, we need to have a certain amount of (range of motion/speed). We need to have a certain amount of (force/velocity) generation. And we need to have the Servo’s within the brains in the body to be able to carry that out. So it really does involve the entire organism. When we start to talk about (movement control/coordination), coordination is a little bit different. Coordination, we’re starting to talk about a multi-system organism that has ankle, foot, mid foot, knee, hip, pelvis, and trunk that has to work together to be able to move forward. So coordination is putting together all of the individual pieces to be able to execute the movement that we are looking for.
control of movement; ROM; force; force; coordination;
The most basic of movements, is the initiation of a ____. There is some sensory stimuli, whether it is air onto the eyeball to create some sort of reflex locally, if it’s a cranial nerve all the way down to a flexor withdrawal crossed extensor reflex happening from sensory and nociceptive input, resulting in multi system contraction. While multi systems are involved, it’s (still/still not)coordination because there’s no thinking involved, there’s no executive processing. All of this is happening at a very simple reflex loop that’s happening at the (brain/cord), right?
reflex; still not; cord
So in order to create movement and control movement, we need an intact (motor/sensory) system. Without (motor/sensory) movement and control, coordination of movement does not occur from a control perspective. If we think about the elbow motion and we think about the force output that needs to occur. We need to have a sense of how much force we are generating, how much force needs to be generated, and where our joint is to be able to guide the movement. That is kinesthesia and proprioception coming from within the (coritcospinal/dorsal column-medial lemniscus). So the information traveling up from the dorsal column-medial lemniscus is critical. All of that goes to the (cerebrum/thalamus) and sent up to the cortical regions. Once that occurs. That same input is then driven into the motor cortices and then sent down into the (ascending/descending) pathways. The main descending pathway, the (anterior corticospinal tract/lateral corticospinal tract). We also discussed the presence of the anterior corticospinal tract, rubrospinal tract. We discussed the presence of the vestibular spinal tracks. And we’re going to go into the cerebellar tracks.
sensory; sensory; DCML; thalamus; descending; lateral corticospinal tract
So as we come to discuss how do we control and coordinate movement, we need to consider that ascending information has to exist. We need to have a way of getting that information down to the end organs, which is our (ascending/descending) information systems. And we need to make sure from a quality control perspective that the output that we are providing is the one that was intended. And it is the one that is appropriate. And it meets the environmental and contextual needs that the organism is behaving in.
descending;
So from an output adjustment perspective, it’s going to be the (cerebrum/cerebellum) that provides for that specific function. The cerebellum has a very interesting histological feature to it. And that cerebellum or little brain. If we break down the Latin roots, we’re looking at something that’s mass equivalent to about - percent of the cerebrum. So it’s a fraction of the size and weight of the cerebrum. But when we take a look at the amount of neurons that are located within the cerebellum. It has roughly (more/the same amount) of neurons as the cerebrum, the brain stem, and the spinal cord combined. So it is a incredibly (loosely/densely) packed structure because of so many things that have to happen. So much information that has to go through, so much information that has to be processed. And it has to be done in real time because we’re talking about milliseconds of correction that needs to happen. You’re going out and you start deviating off. That correction has to happen within a millisecond range. If it’s not, then you start to deviate and you’re off target. So that information has to be processed. It has to be received quickly, and it has to be sent back out quickly to the cortices or modulating within the tracks.
cerebellum; 8-10; the same amount; densely;
But from a gross big picture perspective, what we’re looking at is the (cerebrum/cerebellum) is the comparator. Am I doing what I intended to do? If not, what do I need to do to adjust?
cerebellum
From an anatomical perspective, we have a structure that is similar to the cortex, so the outer shell of the cerebellum. There’s an inner layer of the cerebellum and then there is essentially something that functions like the brainstem of the cerebellum. We’re looking at bottom up (pic to the left). So this is the bottom of the cerebellum. And there are two key structures that I want you to draw your eyes to. The first is this worm-like structure that sits on the bottom. We’ll see that this worm-like structure extends all the way through to the midline of the cerebellum. And that structure is called the ____, like vermicelli, which is also the root word for worm. So vermis comes from the Latin root for worm. It looks like a worm, so we named that vermis. And that is one structure. But that sits on the mid-line. Coming out from the midline, we see these two structures here, kinda like a mustache on the worm. And then these guys down here that are lumps, the mustache kinda that goes through. The vermis is something that we call the _____ lobe. The two areas that we see down here are the cerebellar tonsils. From a function perspective, what’s important is the vermis and the flocculonodular. Those were one of the first to start developing from an evolutionary perspective. And those are also the first to start forming in ______ of the embryo. The tonsils are important because we’re looking at bottom up. The tonsils are important because they sit very close to the foramen (ovale/magnum). So it has a potential pathological feature to it. In the very beginning of the term, last term, we talked about different types of hydrocephalus. And one of the things that can happen, is called a chiari malformation. And in those particular features, just because an overgrowth of the cerebellar tonsils, the cerebellar tonsils will herniate into the cerebellum, into the foramen magnum, creating a blockage within that central canal, which then starts to result in expansion of the lateral ventricles. Pretty sure we went over that. So cerebellar tonsils are not that unique from an individual function perspective. It’s of interest from a potential pathological perspective. We call this the chiari malformation.
vermis; floccular nodular; neurogenesis; magnum;
We’re looking from top down. We have removed the cortices. So here we have the brainstem. So this is the anterior aspect, and this is the posterior aspect. And what is of importance from this picture here is again the continuation of the vermis, the worm-like structure. And then the two cerebellar hemispheres - Just like we have left and right hemispheres of the cortex, we have left and right hemispheres of the cerebellum. There’s an (anterior/superior) lobe and a (posterior/inferior) lobe and functionally, they’re fairly similar. These are just anatomical divisions that I do want you to be mindful of.
anterior; posterior
4 Nuclei Deep Within The Cerebellum
Deep within the cerebellum, we have (two/four) nuclei. Nuclei are clusters of cells that have similar function and similar processes. The fastigial nucleus is responsible for taking in (somatosensory/vestibular) input and integrating that. So where am I in space, where’s my head in space, am I spinning, am i not spinning? The dentate nucleus is one of the (smallest/biggest) nuclei within the cerebellum, and it is responsible for a lot of different things. It plays a role in modifying (movement/senses) and execution of the (movement/senses). So am I deviating off the path? We need to modify it and this is how we’re going to do it. So that’s what I mean by modifying movement planning and execution of that corrected movement pattern, sending it out to the different pathways to be able to correct for it. There’s also good body of evidence suggesting that the cerebellum has an impact on cognition and affect. Just like its role in motor output. It might have an impact on behavioral output in that it is asking the same question. Am I behaving the way I should be? Am I behaving the way I want it to and do I need to correct for that? And then lastly we have the interposed nuclei. There are two of those, the anterior (emboliform/globus) nucleus and the posterior (emboliform/globus) nucleus. And grossly they are looking at, they are modulating and controlling for the precision of (speed of movement/limb movements). So these are deep within the cerebellum. This is where the processing is happening. And that is where a lot of the tracks are going to go through depending on what the tract is responsible for.
four; vestibular; biggest; movement; movement; emboliform; globus; limb movements
Cerebellar Peduncles
Lastly, we have the cerebellar peduncles. Peduncle is a stem of a flowering plant. So essentially the, the cerebellum just looks like a big stock of broccoli, if you kinda look at it that way. And through the stocks we’re getting (afferent and efferent/superior and inferior) input in and out of the cerebellum, the peduncles. If we take a look at this picture here (pic all the way to the left) with the peduncles, structurally it cements the cerebellum onto the _____ as well as connecting it from an information pathway perspective. But grossly there’s a (anterior, middle, and posterior/superior, middle and inferior) cerebellar peduncle.
afferent and efferent; brain stem; superior, middle, and inferior
Out with the old, in with the new
Now the cerebellum itself and all of those different structures that we talked about are organized based on their function. There are three distinct functions of the cerebellum. And we’re going through a stage of name change in terms of what we used to call it and what we’re now calling it.
From an evolutionary perspective, the first thing that formed and continues to function together is the archicerebellar, which is also referred to as the (spinocerebellar/vestibulocerebellar). So the vestibular cerebellar, the components are the floccular nodular lobe which contains the _______ and the (rostral/caudal), or the bottom most part of the worm-like vermis. And the whole purpose of that vestibulo cerebellar unit is to maintain (balance/speed) through vestibular and reticular connections and take that information of which ways up, which ways down, where am I going? Where’s my head going? Because there’s nothing else we need to coordinate at this point. We’re not fully developed yet from an evolutionary perspective.
The next part to develop was the paleocerebellum which becomes the (vestibulocerebellar/spinocerebellar). And so as we started to develop that, what we started to develop from a cerebellar perspective was we made the vermis longer. So we went from the bottom view. We went to the top view. So we took that top view and we started to evolve the vermis a little bit further because now we need a little bit more trunk control to be able to do something with these limb buds that we have. So what developed next was the (lateral/medial) most aspect of the cerebellar hemispheres and the vermis. And the function of that is to coordinate trunk motion and (proximal/distal) limbs.
Now at this point, we’ve got elbows, we’ve got fingers. We need more things to be able to coordinate and control movement. So from an evolutionary perspective, the Neocerebellum developed which turned into the (spinocerebellar/cerebrocerebellar) (aka pontocerebellar) which is the creation of the (cerebral/cerebellar) hemispheres and coordination over the (proximal/distal) limbs.
vestibulocerebellar; floccular nodulis; caudal; balance; spinocerebellar; medial; proximal; cerebrocerebellar; cerebellar; distal
Out with the old, in with the new
From a function perspective. The cerebellum is (ipsilateral/contralateral). So its connection with the cortex is if you have a left sided cerebellar dysfunction, you’re going to have a (right/left) sided limb or trunk dysfunction. You’re going to have a left-sided vestibular dysfunction, similar on the right. So we don’t have to worry about things crossing over and all of that.
ipsilateral; left
So if we overlay Vitruvian Man onto the cerebellum, think of what you have. You’ve got the trunk along the midline, that’s the vermis. You’ve got the limbs on the hemispheres. And then, Ben Lindemann likes to say you’re standing on the flocculus because that’s what’s giving us our balance. So from a gross homuncular perspective and somatotopic organization, that’s what we’re looking at. So vermis, the top portion of the vermis is (trunk/proximal limbs), the middle portion is the (distal/proximal) limbs. And then the further laterally you go out within the cerebellar hemispheres you’re looking at (distal/proximal) limbs, and you’re standing on the floccular nodulus to drive your overall (speed/balance) and where you are in space.
trunk; proximal; distal; balance;
Gross Function of the cerebellum - In order for it to be the comparator, it has to take information. So it’s feedforward/feedback information, constant assessment, reassessment of the movement, correction of the movement as needed. Constant adjustment of movement to stay on target. Again, to emphasize again, in order for us to do that. *(Motor/Sensory) input is absolute. Effector control - The influence over motor output is necessary, but you can’t get any of that without (motor/sensory) input.
Sensory; sensory
So what we have is an individual who’s throwing darts at a target. And she is throwing darts at a target with prism glasses and without prism glasses. The whole purpose of the prism glass - you might see some individuals who have retinal damage, who have prism glasses, if you have retinal damage, one eye isn’t focused and one is, and you start to see double vision. You’ll see people with prism glasses because one eye, the lens shifts where the light’s coming in to reduce the double vision. But essentially what the prism glass does is it shifts what you’re actually seeing. So you might be thinking the target is straight out in front of you, but the targets actually to the left. So what we start to see here is this individual starts to throw darts without the prism glasses on. And she’s fairly on target. You put the prism glass on her and initially, she deviates. So you see that reflection coming down, but there’s a correction that occurs and she starts to come back more to the midline, getting the target. When you take the prism glasses off her.. She was really used to throwing to the right so there’s still an overshoot, but again, she’s able to correct, and re-adjust all within about 50 throws. So that’s what’s happening with somebody that has a cerebellum that’s intact.
Pic to the right:
We have an individual that has either some sort of damage within the cerebellum or some sort of damage to the connections within the cerebellum. No prism glasses, little bit all over the place, but yeah, they’re kinda on target. The prism glasses on and that individual deflects. But if you take a look at what’s happening, There’s no correction back to the midline. It stays deflected until you take the glasses off. The other thing is, once you take the glasses off and they’re on target again, you don’t see this input which was coming from the cerebellum to say, correct, right, correct, right, correct right. You take the prism glasses off, there’s a little bit of a delay because the cerebellum is still kind of saying correct right correct right. You start to see that you’re off target. That information is going back to the cerebellum, adds up, come back left, come back left. We’re not getting that within this individual here. No prism glasses - On target > prism glasses - off target > no prism glasses - on target again.
Got it
So we’ll go into detail on the vestibular cerebellar module first, the oldest, and the component that takes into consideration, where’s my head in space? Where’s my body in space? So that’s the vestibular cerebellar module. We talked about the two components, the (rostral/caudal) vermis and the ______ lobe. Just like anything that processes information, we have afferents and efferents and we’ll go over afferents first. The afferents that are coming in are the ipsilateral CN (VII/VIII) – vestibular portion and the (somatosensory/vestibular) nucleus. It provides information related to a head and body position in space. And this is where things start to get really funky. If we think about what’s happening at this point in the brainstem where the cerebellum sits. We have various descending tracts that may or may not have crossed over yet. We have several ascending tracks that may or may not have crossed over yet. If we’re dealing with the anterolateral system, It (has/hasn’t) already crossed over. If we’re dealing with the dorsal column-medial lemniscus system, it’s not crossing over until it gets to the (pons/medulla). There are other sensory tracts that we haven’t discussed yet, which we were not going to go into the actual anatomical layout of those. But there’s different areas that these ascending information and descending information crosses over. So because of that, what we have is within the circuitry and all I want you to respect about this process is there’s a lot of crisscrossing fibers that occur in order to keep that (ipsilateral/contralateral) cerebellum and (ipsilateral/contralateral) cortical input working. So this goes into Nicole’s question about the crossover. It needs the crossover because some things have crossed over, some things haven’t all of this crossing over and decussations. And we’re not, don’t worry about the details, just understand. There’s a lot of crisscrossing networks that are happening to try to pull in the information. If I’m the right cerebellum and the information’s on the left side, I gotta cross over on that left side, pick it up and bring it back. If it’s already on the right side, I’m just going to stay on the right side and bring it back up. So all of that kind of highway network is just to keep everything on the same side. What we do want to keep in mind though, is just like we had with the anterolateral system where there’s crossovers happening. If the damage is on the left side, you’re going to have (right/left)-sided deficits. If we have damage on the midline, we’re going to have (unilateral/bilateral) deficits. Why? Because all the crossovers getting impacted in some way, shape, or form. So as long as you have that in mind, we’re good. Alright?
caudal; flocculonodular; VIII; vestibular; has; medulla; ipsilateral; ipsilateral; left; bilateral
So from an afferent perspective we are dealing with the vestibular nuclei. And then input onto the (dentate/fastigial) nucleus. From there, information is processed within the fastigial nucleus and it is sent to these aspects - _____ and ______ lobe. So here again, we’re looking at the bottommost parts of this which is the caudal vermis. So information is sent to the caudal vermis and the flocculonodular lobe. Once this has all been processed within the fastigial nucleus - This is the vestibular input > Am I staying on track? Nope, I’m not staying on track. These are the corrections that we need to make. We’ve processed that. Now. We’re going to send it out to the caudal vermis in the floccular nodulus. And then from there, it’s going to be sent out to the (anterior vestibulospinal tract and the posterior vestibulospinal tract/lateral vestibulospinal tract and the medial vestibulospinal tract). We went into those a little bit when we went over tracks, but we’ll review those again in a little bit more detail.
fastigial; vermis; flocculonodular; lateral vestibulospinal tract and the medial vestibulospinal tract
From a peduncle perspective the vestibular information is being carried through. So all of the input that’s crossing over is traveling through the (superior/inferior) cerebellar peduncle on its way to the nucleus to be processed, to be sent out to the _____ and _____, and then eventually out to the vestibular spinal.
inferior; vermis; flocculonodular;
Vestibulocerebellar Module
From an efferent perspective, the efferent output is going through a couple of different places. The (spinal cord/cortex) to the motor outputs to be able to impact that in case there’s any cortical adjustments that need to be made. (Visual/Vestibular) nuclei, specifically, the vestibular nuclei that are interacting with (motor/sensory) nuclei that are associated with ocular motor control. Because it doesn’t matter what you’re doing with the head and body. If you aren’t looking the right way, you still don’t know what you’re doing. So yes, we need to make motor adjustments to the head and body to be able to correct for improper movement. But we still need to be able to see which way we are going and we need to keep an eye on the targets. So cranial nerves (3, 4, and 6/ 3, 4, and 5) are going to be involved in terms of efferents, to be able to pull the correct information and produce the appropriate response for us to stay on track. And then also the reticulospinal tract from the (reticular/somatosensory) nuclei. We talked about the reticular formation and its impact on several different functions like arousal, alertness, and sleep. Understand and respect that those proximal limbs to some degree, but mostly the trunk musculature has to be pulled in to be able to control for movement. Why do we have the reticulospinal tract and the reticular nuclei coming in, as well as the cortex? If we think about the information that’s being adjusted at the track, that processing happens quickly. So it is a (speed/precision) thing. Cortical function takes a little bit of time. So you’re on the edge and you’re about to fall. You want that to be done quick, right? So where is that information going to go? Let’s go into the tracks. That needs to happen right away. You have some time to think about it and process it. It’s not urgent. And it might need more skill, correct? That information is going to go to the cortex. So that’s why we have these different divisions coming into play. Because some of these things might have that happen quickly. Some of these things we might need a little bit more skill in a little bit more time. So that’s where the division comes from. And just remember, standing on the ________.
cortex; Vestibular; motor; 3,4, and 6; reticular; speed; flocculonodular
Vestibulocerebellar Module
If we go back to the section of the spinal cord, anything that’s posture and control related, sit on the (midline/lateral edge) from a descending tract perspective rank. So we have this same picture that we went over a great deal. We left out a couple of parts. We’ve got the lateral vestibular fibers in blue, and the medial vestibulospinal fibers in red. The medial vestibulospinal fibers going to come down the midline and they’re going to be responsible for controlling (head and neck/limbs and trunk) musculature, control my head and space and secondly to stay on track - turn my head to the left or right as I need to so I can keep my focus on the target if there is a target I need to keep in mind. And then the lateral vestibulospinal fibers is going to continue down into the lumbar segments to be able to control the (head and trunk/limbs and the trunk musculature and the pelvic musculature) to be able to control for gait and balance. So those are all the individual components that we see from a vestibular cerebellar module perspective.
midline; head and neck; limbs and the trunk musculature and the pelvic musculature
If we’re dealing with the vestibulocerebellar module, if there’s a dysfunction within that module, these are the more common deficits that we’re going to see. Deficit in pursuit (nose/eye) movements and (stroke/vertigo). So the vestibular systems off, the input from vestibular system to the eyes are odd. So there’s going to be some function there that inhibits or interferes with proper eye movement. The other aspect then is something that we call (funcal/truncal) ataxia, used to be called drunken sailor syndrome. A generally (narrow/wide) base stance of ambulation is what we are looking and it is a wide based stance of ambulation because you’re trying to bring your center of mass under your base of support. But if you don’t really know where your center of mass is going to be, what do you do? You widen your base of support. So you’ll see individuals walking with a wide base stance and an ataxic gait, which is kind of like an uncoordinated type of a gait pattern.
With truncal ataxia there is a tendency to fall (to the side of/ away from) the lesion
eye; vertigo; truncal; wide; to the side of
From a spinal cerebellar module perspective. The afferent information that’s coming in, the sensory information coming in comes from these two tracks. So it comes from a couple of different places, but I highlight these two tracks because these are tracks that we haven’t gone over yet. So (posterior/lateral) spinocerebellar tract and the (anterior/medial) spinal cerebellar tract, sitting on the (medial/lateral) aspect of the cord, is going to contribute information directly from the spinal cord to the cerebellum.
posterior; anterior; lateral;
The efferents that the spinal cerebellar module is going to send information out to, is going to be the (cortex/basal ganglia), (visual /vestibular) nuclei, and (extensor/reticular) nuclei, which is similar to what we had before, with the caveat being the red nucleus. The red nucleus comes into play if you go back to week three or week four to the (spinovestibular/rubrospinal) tract and there were inhibition and excitation of (proximal/distal) limb musculature that was happening from the rubrospinal tract. So again, this has to happen quickly. If it has to happen quickly, we’re going out to the (cortex/spinal cord tracks). If it’s quick and it’s gross and it doesn’t need a lot of skill, and it’s just stepping back so I don’t fall, let’s bring it down to the tracks and let’s let it happen quickly. If it’s something that needs a little bit more skill, let’s make sure we send this information to the (cortex/spinal cord tracks).
cortex; vestibular; reticular; rubrospinal; proximal; spinal cord tracks; cortex
So function of the spinal cerebellar is to modulate control of (axial/appendicular) musculature and (distal/proximal) limbs. And that’s where the vestibular nuclei again comes into play. Because we need to have (vestibular/visual) information to help with axial trunk musculature control.
axial; proximal; vestibular
Spinocerebellar Module
From a pathway perspective, we’re dealing with the middle cerebellar peduncle. So the mid cerebellar peduncle is going to connect the cerebellum to the (pons/medulla). It’s a little bit (thicker /thinner) than the inferior cerebellar peduncle because the inferior cerebellar peduncle has predominantly (afferent/afferent and efferent), while the middle cerebellar peduncle is going to have a combination of (afferent/afferent and efferent) cerebellum information to and from the cord.
pons; thicker; afferent; afferent and efferent
Spinocerebellar Module
Picture gets a little bit more complex, but again, don’t worry about each individual output circuitry. Keep the big picture in mind and focus on the circle and the boxes. Alright? So if we take a look at where the olivary nucleus sits (pic to the right), we’ve got these two things running anterior to posterior, and that’s the medial lemniscus, and what’s being carried there? So we’ve got the (cortex/dorsal column-medial lemniscus) carrying information for fine touch and proprioception and that is a budding right next to the olivary nucleus. What do we have sitting here? These two structures are the pyramids sitting along the (medulla/pons) (bottom structure on pic to the right). What’s coming across the pyramids within the medulla? The (anterior and lateral/superior and inferior) corticospinal tract. What’s being carried within the anterior and lateral corticospinal tract? The (ascending/descending) input from the cortex down to our lens. The anterior corticospinal tract carries the (trunk/limb) information and the lateral corticospinal tract carries the (trunk/limb) information. Remember that the spinocerebellar module modulates control of axial musculature and proximal limbs. So what is happening here? If we take a look at this picture here, we have just a ton of (motor/sensory) information that’s coming in just because it sits right next to the medial lemniscus. We’ve got sensory information that’s coming in from the medial lemniscus into its neighbor – the (grape/olivary) nucleus. And then from this olivary nucleus, it’s taking all of that sensory input and sending it to the two (anterior and posterior/superior and inferior) interposed nuclei (Anterior emboliform nucleus and Posterior Globose nucleus). Information is going to be processed. They’re going to figure out what needs to happen, if anything needs to happen, and if anything needs to happen. The next relay circuit is information is going to be sent down to (spinovestibular/rubrospinal) tract and the (anterior/lateral) corticospinal tract and this is all sitting within very close proximity of each other. That’s it for this tract.
DCML; medulla; anterior and lateral ; descending; trunk; limb; sensory; olivary; anterior and posterior; rubrospinal; lateral;
Cerebrocerebellar Module
The cerebrocerebellar/ pontocereballar module is more complex because it is responsible for the (proximal/distal) limbs. So if we think about everything that is involved in the distal limbs and all of the musculature in the distal limbs… If we go back to homunculus representation from a sensory and motor perspective, what gets the larger homunculus presentation? The things that need the (gross/fine) motor control. So there’s a large representation within the motor homunculus. And we also have a large representation within the cerebellum just because of all the things that need to be corrected and all the things that we need to do correctly with our end organs, depending on what it is that we need to do. So from an afferent perspective there is a structure that we refer to as the pontine nuclei. And all I’m really going to say about the pontine nuclei is it’s an area that sits in the (medulla/pons) and it gets a lot of (motor/sensory) input. At this point in the game from a physical therapist anatomical perspective that’s all we really need to know. The pontine nuclei is going to be collecting a good amount of the sensory information. It’s also going to be taking input from the thalamus. Because where’s all the sensory information going once it leaves the spinal cord? Regardless of if it’s dorsal column or anterior lateral, it’s all going to the (spinal cord/thalamus). So you have a common collection point. So from that common collection point within the thalamus, we’re going to send that input to the cerebrocerebellar module. The red nucleus and the spinal cord are just collecting different types of (motor/sensory) input in terms of what the body’s doing. And then we have the primary (auditory/visual) cortex. The primary visual cortex has a large representation within the cerebellar module especially because vision is so important. If it’s intact it is one of the most important sensory systems that we have in terms of guiding movement. So these are all the inputs that are coming into the cerebrocerebellar module.
distal; fine; pons; sensory; thalamus; sensory; visual;
Cerebrocerebellar Module
Information is going to come in via this structure here, the (inferior/superior) cerebellar peduncle. It makes sense if it’s the (inferior/superior) because the information that it’s taking from sits higher than the cerebrum.
superior; superior;
Cerebrocerebellar Module
So from an efferent perspective, it’s all the things that are going to be sending information to the limbs. The rubrospinal tract is going to send information to the (cerebellum/thalamus) so it can get to the (cerebellum/cortex). And then from there we’re going to have much more (gross/fine) motor coordination. And so the whole purpose of this cerebrocerebellar/pontocerebellar module is to impact the planning, the control, and the timing of (precise/velocity) movement of the extremities. So these are the things that we’re looking at. It is going to have a much bigger representation within the (primary/premotor and supplementary) motor areas. Because the (primary/premotor and supplementary) motor area is just execution and how much force we need to produce that motion. All that planning and all that correction happens within the PMA and the SMA with M1 - this is what we’re going to do and this is the amount of force that we need to produce.
thalamus; cortex; fine; precise; premotor and supplementary; primary;
Ben says we need to know this > From an architecture perspective the cerebrocerebellar module is the only one that (single/double) crosses. So we go back to the question about the decussation. There’s just a few more crossovers. And there’s more crossovers because the regions that this cerebral cerebellar module is communicating with are all over the place. Again. Think big picture. The whole reason for the double crossing is because it’s trying to keep the left side of the cerebellum working with the (right/left) side of the cortex. That will probably be on the exam because Ben says it’s important.
double; left
Cerebellar Blood Supply
We have three main arteries that we are dealing with. The first main artery comes off the vertebral artery, and that is pica - posterior inferior cerebellar artery. The name describes the region of the cerebellum that it profuses - (anterior and inferior/posterior and inferior). Off the basilar artery, we’ve got the anterior inferior cerebellar artery, which profuses the (anterior and inferior/posterior and inferior) cerebellum. And then we have the superior cerebellar arteries, which profuses the (inferior/superior) aspect of the cerebellum. So profusion is a little bit easier with the cerebellum. Just understand what comes off the vertebral artery and what comes off the basilar artery.
posterior and inferior; anterior and inferior; superior;
From a cerebrocerebellar module dysfunction you might see some of these, you might not see any of them. As you have a hard time identifying how much force you need to produce there will be disturbance to their visual pursuit because of the impact from the oculomotor perspective. Unsteady gait. There’s a tendency to fall (towards/away from) the side of the lesion. So if there’s a right-sided cerebellar dysfunction, you’re going to fall towards the (left/right) side. Dysmetria, which is past pointing. So if, if I’m thinking of dysmetria, if I want to point towards that TV over there, I’m going to try to point to it, but my targets off, I’m going to go off to the left and then I’m going to come back. So you skip the target and then you’re able to come back to it. And then dysarthria- I think dysarthria. It has gotta be one of the most frustrating things for a patient. Just because dysarthria impacts your ability to produce (speech/vision). So you’re trying to talk and your tongue twists left to right. You know exactly what you want to say, but your tongue twisting. So the sound that’s being produced is not right or you’re trying to talk, but your mouth deflects left and right and you’ve got no control over it, right? So the words that are being produced do not sound clear.
towards; right; speech;
The other thing that we’ll see with the cerebrocerebellar module dysfunction is something called this dysdiadokinesia. So for us to do this, taking both hands, flip them left, flip them right, we are able to do that. Somebody with this dysdiadodyskinesia just (can’t do that/does it rapidly) motion and they just kind of sit there. And so it’s an inability to perform (rapid alternating/slow non alternating) movements under control. Intention tremor - That’s going to be different from something that we call resting tremor, which is going to be involved in a different motor system that we’re going to go over with an intention tremor. So i’m sitting here. I’m fine. And then I start to move. And as I start to move, there’s a little bit of tremor because the (fine motor/gross sensory) coordination has been impacted a little bit. So instead of making small adjustments to my movement, the adjustments are (smaller/larger) just because of the amplitude control. So can you point to your nose? Fine, but you might have a little shaking going on. And that’s intention tremor.
can’t do that; rapid alternating; fine motor; larger;
So to summarize it all, the big picture that I do want you guys to keep in mind. Don’t worry about all of these individual pieces right now. Understand where the pieces are coming from, where the afferents are, what the efferents are, and just understand that all the crossovers are to keep things (ipsilateral/contralateral). If we have laterality in the injury, there’s a left sided injury or right-sided injury. It’s going to impact that side of the body. If we have an issue that is midline, then it’s going to impact (one side/both sides). Good on that. All right. That’s it.
ipsilateral; both sides
