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BIOL 2301 Human Anatomy & Physiology I - BIOL2301_lecture24_1117
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00:02 All right, good morning. Was it hard getting here this
00:07 Like, yeah, I mean, every ounce of energy I was sitting
00:10 my office at 715 and I couldn't focus. My eyes were so blurry
00:15 because like, you're not supposed to here and, you know, I
00:21 just the way the schedule works. I could, I would have canceled
00:24 too. Right. I'm like I, I'd rather sleep in.
00:28 , but today, what we're gonna is we need to finish up.
00:30 have two more lectures to go. . We're gonna talk about uh motor
00:34 and then when we come back on , after we filled ourselves turkey,
00:39 get our special fall break right before . I mean, it's the stupidest
00:43 ever, right? I mean, Thanksgiving but having a break like the
00:48 being, um, what we'll do we'll do the nervous system and u
00:54 when we go through pathways, you're see a lot of really, really
00:57 names that are very, very But they'll be, we say we
01:01 a, we have a question, is it coming from and where is
01:04 going to and it should tell us we need to know about that
01:09 And so this is what we're talking motor pathways. And the good news
01:13 that they're not particularly, they're gonna like it, but they're not um
01:19 we have is we have things that polysynaptic poly means more than one.
01:24 there's gonna be more than uh uh two neurons. Well, it's gonna
01:29 two neurons, but there's usually going be more than one synapse. And
01:32 , it's polysynaptic because we're gonna be lots of different parts of the
01:36 Now, here's the good news in class. Remember this is what we
01:39 a freshman level course or a sophomore course. And we're not going to
01:43 there and say we need you to every step of every type of movement
01:46 you're ever gonna do. We're gonna some very generic overviews of the
01:51 All right. So that's kind of way that you should be looking at
01:54 is what does this look like All right. So that's kind of
01:59 descriptive descriptions. So, generically, motor pathways are going to begin in
02:04 or two places. It's gonna start here at the cortex or it's gonna
02:07 down here in the brain stem. right. So we already know that
02:11 gonna be two types, one that's , one that's brain stem, what
02:16 gonna do regardless of where you start you're gonna travel down the spinal cord
02:20 then what you're gonna do is you're terminate, start a second neuron and
02:24 that's gonna go on to the effector . The effector organ generically is gonna
02:29 a muscle or a gland. All . Now, the whole time we're
02:32 talk about this, we're just gonna talking about muscles, right? But
02:36 doesn't mean that glands are not included these mutter pathways. So like when
02:40 salivate, you're sending a signal to salivary glands to start squirting juice.
02:45 right. So that is, it , it's actually called salivary juice.
02:49 , right. So the idea here a motor pathway is something, sending
02:53 signal to make something happen cause whatever effect is. All right.
03:00 functionally, this is what we think skeletal muscles and we rarely think about
03:05 autonomic contractions. And so we're thinking movement, but also posture and balance
03:11 muscle tone. All right. So just sitting there, your motor pathways
03:16 incredibly active, making sure that you're up, right? And your head's
03:20 flopping around and you're not sliding out your chair. All right. With
03:26 in mind, we've already talked about they originate right? To get input
03:35 different parts of the brain. We're go back to that basal nuclei.
03:39 memorize a whole bunch of things and like, I don't know why I
03:42 to memorize this stuff today is the we come back to that. All
03:45 , we're gonna be looking at the nuclei again generically and we're gonna look
03:49 a couple parts of it and seeing it plays a role in this.
03:52 the other place is the cerebellum, said the cerebellum was a structure that
03:56 created that was kind of put off the side to do special processing for
04:01 , right, to do calculations. so in order to move, we're
04:05 have to use those calculations. So cerebellum is gonna play a role.
04:09 , the good news is that not do we have two simple systems,
04:13 we have two simple neurons in our . We have easy names for
04:18 One is called the upper neuron. is called the lower neuron that makes
04:22 easy, right? So the upper is going to be the one that
04:26 either in the cortex or in the stem and travels down the spinal cord
04:30 ends up in the spinal cord. lower neuron is the one to which
04:33 synapses. So it begins in the cord and goes out to the muscle
04:37 the gland. There is not a neuron. Yay, that makes it
04:44 . All rights are direct and All right, pause time out when
04:49 hear direct. What does that mean you straight too? What is
04:55 not straight. All right. So kind of gives you a sense of
04:59 what happened here is that they discovered pathway and they said, oh,
05:04 something all we have here. It here and it goes right down to
05:08 muscles. So I'm just gonna just it away here. So the directs
05:12 the ones gonna begin in the They're like, oh this is
05:14 It goes right down to, it direct to the muscles and then they
05:19 weight, not all movement begins in cortex, it begins someplace else.
05:24 these are not direct, they are , right? So the ones that
05:29 basically begin in the brain stem are indirect pathways. So that makes it
05:33 of simple. All right. we're gonna walk through them so that
05:37 understand them. All right. with regard to the lower motor
05:42 it was no, that was just pathways. All right, this is
05:46 seem much more confusing because as I this, I realized my language sucks
05:50 I wrote this down in the So I'm gonna try to walk through
05:54 . All right. So the cell is gonna be localized to the ventral
06:00 . All right. Why the ventral ? Well, because that's where we're
06:07 . Um It can also be found some cranial nuclei and that's when we're
06:11 be dealing with stuff in the head neck region. So for example,
06:14 glands, right, we're gonna leave spinal cord. This isn't new via
06:21 ventral root. So here you can I'm over in the ventral horn
06:24 I come and off. I go my skeletal muscle. Now,
06:29 always, always no other ex uh are no circumstances where this is not
06:34 . This is like the one place you could say here's an always lower
06:39 neurons are always excitatory. So if excite an lower motor neuron, I
06:44 a contraction. If I stop sending signal, it relaxes. All
06:50 So lower motor neurons are always they are never inhibitory. All
06:56 So if I'm trying to inhibit muscle , what would I be doing is
07:00 would be blocking excitatory neurons, So I'd be upstream of that,
07:06 . So the upper neurons can be or excitatory, but the lowers are
07:12 excitatory. Now, this is where gets kind of funky. So here
07:17 are, we're looking at a All right. And what we have
07:21 is we have two different types of neurons that are part of this lo
07:26 motor neuron. You can either be alpha or a gamma. All
07:31 These are both mo uh motor neurons send excitatory signals to cause a muscle
07:37 contract. All right. But the that a muscle works is you have
07:42 fibers that are responsible for the majority the contraction. And then you have
07:48 group of muscles that play a role detecting the degree of stretch in that
07:56 . All right. So the muscles the outside, the things that play
08:00 role in contraction are what we refer as the extrafusal muscle fibers. Then
08:07 the packed inside those extrafusal is kind this connective tissue structure where you have
08:12 intrafusal muscle fibers. So, extrafusal the outside, intrafusal, on the
08:18 , the inside part is wrapped in tissue. The alphas go to the
08:24 , the gammas go to the intrafusal together they will cause that whole unit
08:29 contract together. All right. Now intrafusal muscle fibers? Well, they
08:37 a group of muscles that act like this is where my English is
08:41 right? So I have a a here and it's like the question
08:45 what is this, this statement down ? So it's not the gammas that
08:49 as appropriate receptors. It's the skeletal . So this group of muscles serves
08:55 a proprioceptor for that muscle group. right. So how do you know
09:02 high to raise your hand? When someone waves, well, you
09:06 a contraction that your brain is sending to the extrafusal fibers and the
09:12 But the intrafusal fibers are the ones are being measured to look at the
09:16 of stretch. If the degree of is too much or too little,
09:19 make corrections. All right. So can see here there are sensory fibers
09:26 in with those intrafusal fibers So we're the degree of stretch of this whole
09:33 based on the amount of stretch going inside there. Does that make
09:40 Ok. If it doesn't make we're gonna come back to this like
09:44 very end of the lecture. All . But I want you to understand
09:47 the lower motor neurons are the ones are directly innervating and they are both
09:52 alphas and these gammas and they're working to make sure the muscles are,
09:57 contracting to the degree of contraction that want it to contract. All
10:04 so far, are you with Ok. Now your body, this
10:08 not new. This is something we've about multiple times. Your body demonstrates
10:14 organization to it. And so your cord is going to represent that
10:20 So this is what we refer to somatotopic. Um And so here is
10:25 example of your body. You can here is my head and I had
10:28 down my arm. And so if were to look in the gray matter
10:33 that ventral horn, I would find muscles that are being innervated are coming
10:38 lower motor neurons from the medial side the gray matter. And as I
10:42 laterally, I'm further and further Now, this is something that you
10:47 already familiar with. If you're driving the highway and lanes are emerging
10:51 you're being pushed further and further and to the left. Right.
10:56 The lanes are coming and as lanes , you're now moving further and further
11:01 the right without even having to change . Right. It's just, if
11:04 have three lane highway, it turns a four lane highway, I get
11:07 over a lane. Right. And kind of what's going on here is
11:11 the wires, your nerve fibers are coming in and they're pushing things over
11:17 over and over. And that's what somatotopic is. And so when we
11:22 at the spinal cord, generally we look at the brain, that
11:27 is going to be conserved. And part of the reason why your brain
11:30 where information is coming from because it that information. We've talked about motor
11:38 . I'm just throwing this in here that if you don't remember what a
11:40 unit is, you don't have to look it up in unit two.
11:44 right. So I'm just gonna That's like, all right, when
11:48 get to the upper motor units, again, don't be freaked out by
11:51 picture. I'm not making you memorize organization here. What we're talking about
11:56 we're looking at a special group of that are processing that information they're located
12:02 in layer five. And again, not gonna ask you which layer are
12:05 located in? Because it's not that . But I want you to just
12:09 demonstrate because we mentioned this before. that, hey, the cortex has
12:12 six layers and processing is done in six layers. And it's here that
12:17 cells are originating in the primary motor . And what they're gonna do is
12:22 going to Decca at some point before get down to the lower motor
12:27 And so what that means is is the right side of your brain is
12:31 affect the left side of your body the left side of brain affects the
12:33 side of your body where it decussate upon what type of fibers we're looking
12:38 . All right. So most of , when we're dealing with the direct
12:41 , it's gonna be primarily up in brain stem. So you're gonna see
12:45 crossing in the medulla where the pyramids located, but we're gonna see some
12:49 don't do that. They wait until get down to the very bottom.
12:53 you're in the spinal cord and that's they cross over. All right.
12:58 , there are interneurons in here. said this is polysynaptic. All
13:03 And when we say polysynaptic, that more than one synapse. But if
13:06 have two chain or two neurons in chain, you only have one
13:09 right? So why is it Well, because there are other interneurons
13:16 . All right. So whenever we a contraction in an extensor, we're
13:20 to cause relaxation and a flexor, flip those around flexor extensor. All
13:26 . So that happens because there are synapses there. We are trying to
13:31 a simple model. So we understand to lower muscle, right? But
13:37 sort of movement is gonna be lots lots of neurons involved. It's a
13:41 complex process. And as I upper neurons can be excitatory or
13:50 So the lower motor neuron coming here going to excite and so the upper
13:56 neuron going to that lower motor neuron going to be excitatory. But I'm
13:59 send also an inhibitory signal here to that extensor from contracting or really the
14:08 on this side from contract. I the extensor to contract. All
14:12 So there's a certain degree of antagonism on at the level of the upper
14:18 neuron. Do you remember this The weird one, the mo the
14:25 motor homunculus. All right. And , I'm just throwing this up here
14:30 I want to remind you that this the origin of these upper motor
14:36 All right. So the signal to you wiggle your tongue originates here.
14:41 mean, the signal to tell that to to contract originates there down.
14:50 you think about wiggling your tongue, your thinking about wiggling your tongue originate
14:55 ? Where do you think it originates here? Right? Frontal lobe,
15:03 ? This is where all the thinking the planning takes place. So you
15:06 already see that this is not the where the thought of it begins.
15:12 where the signal to make the muscle begins. All right. So that
15:17 we're gonna have to send information to primary motor cortex to make it do
15:22 job. Ok. Put another way in your car, you want your
15:28 to go. How do you make car go press the gas? But
15:32 you ever opened up the front hood the car? Is there more to
15:36 car than just a gas pedal and gas tank? Oh, yes,
15:40 goodness. Yes. Right. There many, many other things that affect
15:45 go. Right. And that's kind what we're referring to here is that
15:50 understand how the information makes or how signal gets down to the muscle.
15:55 we're kind of looking at the stuff makes this happen. All right.
16:01 , we've already talked about all this . All right. So we have
16:03 map it, it exhibits of plasticity we have very specific areas due to
16:09 and this path, I mean, don't even talk about some of these
16:12 , but so here's your motor And what we're gonna be looking at
16:16 is we're looking at this thing called premotor cortex. You can see there's
16:20 supplementary motor cortex, there's association we have other areas that are involved
16:25 I'm just trying to keep this as as possible. All right. So
16:30 does this do? All right. has some upper motor neurons,
16:35 So it can't actually send signals, generally speaking, what it's doing is
16:39 working in association with the primary motor to get moving happen. All
16:46 Again, organization, soma atypic meaning going to follow the same sort of
16:53 . So what it's gonna do is going to initiate the signal first that
16:59 tells the primary motor primary motor cortex to do. All right, it
17:05 responsible for storing your motor memory. , motor memory is kind of a
17:11 term. All right. So for , if you were to dribble a
17:16 , right? That is not motor . All right. That is a
17:20 action that's actually stored in the All right, motor memory would be
17:25 like, oh what am I supposed do here? Like the example I
17:30 up here is like, what's a five versus a wave? Right?
17:36 mean, they both require the same lifting up your hands and then doing
17:41 with a wave. What do I with a high five? What do
17:44 do? Right. So it's knowing to do in context. That's the
17:50 memory, right? Walking and tap are very similar things, but they
17:57 not so similar that you would confuse for the other, right? That's
18:02 idea here. All right. The thing that it does, it plays
18:06 role in sorts of movements that are to visual or sound cues. Now
18:11 , this is not reflexive sound or movement. All right, that's going
18:16 be at the level of the vestibular or the level of the brain
18:20 But the idea would be, um example, um you know, I
18:25 , I'm not saying like turning your but you know, some sort of
18:28 cue you see uh a football come . That's the, the, the
18:33 is to protect myself, but you yourself to do what catch the
18:38 right? So that would be the cue. I'm watching, I'm
18:42 I'm grabbing the football. That would the idea here. All right.
18:47 they can send directly, but generally , it's motor cortex. So the
18:51 that you think of the premotor cortex it is talking to the motor cortex
18:56 the primary motor cortex. Notice I one, the we're not talking about
19:03 supplementary motor area. We're just, moving on to really, this is
19:08 day to do that kind of makes want to go to their office and
19:20 banging on stuff while they do it you do know it's windy, they're
19:27 gonna blow right back. At least getting paid. All right. So
19:35 areas, remember with association areas, take information and we put things together
19:39 make actions happen. All right. the uh the association areas we're interested
19:46 are the prefrontal association and the posterior . All right. So, with
19:51 prefrontal, what we're gonna do is going to talk to that premotor and
19:55 primary motor cortex and this is making that you understand what you're supposed to
20:01 doing. This is basically the thinking . All right. Oh, I
20:05 the ball coming to me. What I supposed to do? I'm supposed
20:10 , you know, catch the ball move to the ball or whatever it
20:14 . That is the idea of what frontal lobe is responsible for and what
20:18 association area is here. All the posterior parietal. Now, on
20:23 other hand, is taking information from somatosensory cortex and it is making sure
20:28 you're doing the precise muscle movements. other words, you are uh refining
20:35 in response to uh the sense of or even with regard to vision,
20:42 know. So remember we talked about occipital lobe being primarily vision, but
20:46 occipital information moves or that vision information upward. And so you're coordinating things
20:53 , right? So this information is taking input and then sending it
21:00 to help refine how your movement is gonna happen. So, associations are
21:06 are important for that reason. So down, all right, this is
21:14 the brain stem plays a role in information. There's two different areas of
21:20 for us. All right. The is the vestibular nuclei uh in this
21:25 , it's not a great picture. you can't orient yourself. So here
21:28 can see cerebellum, this is brainstem down the green jelly beans here represent
21:35 vestibular nuclei. So the information is in and coming back to the
21:39 You can see that right information does down to the vestibular nuclei. Also
21:44 reticular formation, which is just this area uh through the middle of the
21:50 stem and remember what is the reticular for alertness? The idea of keeping
21:56 body awake, sending signals all over brain and vestibular. When you hear
22:00 , what should you think about Ok. So vestibular, remember we
22:07 learned about the inner ear, the apparatus. That's where all the equilibrium
22:14 is located. All right. So gonna come back to the vestibular
22:20 but information is going up and coming through those areas to help us kind
22:25 know our position in space, the nuclei we've talked about and we named
22:31 the a couple of these structures. again, we're not gonna go through
22:35 say, please identify which one does want. What I'm trying to do
22:38 I'm trying to paint a broader picture . All right. So what it
22:43 in a very generic sense is it antagonistic or unnecessary movement? All
22:48 And we've talked a little bit about . We did this previously and we
22:52 , hey, you know, when move, there is unnecessary movement that
22:56 blocked. So I don't actually visually what's going on. So for
23:01 if I go and grab a uh cup, I got one right
23:05 Thank you. You know, you see it happening, but my hand
23:10 overshoot and undershoot. So when I into it, I'm moving like so
23:14 because I'm doing it before the actual takes place, it smooths it out
23:18 so I can go and grab something straightforward. But in Parkinson's which affects
23:23 basal nuclei, you don't see that , you see the tremor because that
23:28 antagonistic movement does not get blocked. again, this is a review
23:36 So if you get lost, you to flip back and ask these questions
23:39 these structures are. So we're going be looking at the globus claus.
23:44 it's this region in here for the part. But other ones are going
23:47 be uh taking uh uh playing a as well. All right. So
23:52 , I'm not going to walk through . They're just there for you.
23:56 is the fun map. All Again, this is not a memorization
24:00 . This is a, let's try understand it map. First of two
24:11 , Gaba and glutamate closely related to other. Gaba is the inhibitor glutamate
24:17 the excitatory neurotransmitter. So Gaba is as a brake glutamate is acting as
24:24 gas pedal. So what you can is that the thalamus plays an important
24:30 in activating or exciting the motor That's what the green arrow represents.
24:36 I'm adding gas to make the motor work so that I can get a
24:40 contraction. The problem is, is thalamus is a little bit over
24:46 In other words, what it does when it sends signals, it just
24:49 all the signals right. So this where you get that antagonistic move,
24:53 hand is going this way. no, no. Go that
24:54 go this way, go that go this way, go that
24:56 And it's sending information too quickly in motor cortex. It's just sending the
25:00 and that's why you get this really . So what we need to do
25:03 we need to inhibit how often the sends the information. All right.
25:09 so this is the role of the nuclei, which is what all the
25:14 here represents. So you can see our little cartoon, right? We
25:18 this portion, the globus polatis, internal globus potus plays a role in
25:24 the thalamus acting as a break. right. So if I push on
25:28 break, that's going to inhibit the , ignore the colors of these two
25:33 , right? So if I inhibit thalamus, then it is no longer
25:37 the motor cortex and the motor cortex no longer sending a signal. Does
25:41 make sense? So I'm blocking All right. If I take away
25:48 blocking of ex citation. What do get? I have a negative and
25:53 positive if I take away the what do I get the positive?
25:56 get excitation? All right. So I'm doing is I'm regulating the
26:03 Ok. Now, when I regulate regulator, I can regulate in one
26:06 two ways I can positively regulate or regulate. All right. So I
26:11 inhibit or I can excite if I the negative regulator, what I'm doing
26:17 I'm pressing on the brake, So here I'm just trying to show
26:22 here if I stimulate the internal globus , what does that do? That
26:27 the release of the inhibitory neurotransmitter which the thalamus. If I block the
26:34 , I don't excite the motor Do you see how I'm doing this
26:37 ? Each step is doing so, let's do the opposite. If I
26:42 inhibiting the internal Globus palas, I'm longer inhibiting the thalamus. Does that
26:49 sense? Right. Two negatives make positive? Right. So if I
26:55 the inhibitor, I'm allowing the thalamus stimulate the motor cortex, which causes
27:00 muscle contraction. So do you see we're doing here is we're, we
27:05 have a system that is just gonna constantly on. And so what we're
27:09 is we're turning it on and on and off, on and
27:11 on and off, on and depending upon specific needs, right?
27:15 what's going on here. All So the internal, internal globs Palat
27:20 inhibit this activity. And so I directly uh uh interfere or directly activate
27:31 system. That's what they say. speaking, the basal nuclei acting on
27:35 own internal parts can either excite it inhibit it. And so if I
27:40 it, that means I block, means this stuff gets blocked or I
27:44 block this, which doesn't block which now allows this to go
27:49 That makes sense. Yeah, I that blank look. Yeah, you're
27:57 . Yeah, up there. OK. I mean, you woke
28:01 early today just to be here. could be driving home and eating turkey
28:06 . Well, really Thursday. But , sir, we're gonna get to
28:12 in a sec. All right. gonna be the indirect pathway. All
28:18 . Now, this is not the and the indirect pathway of the motor
28:22 . This is how do we influence basal nuclei directly or indirectly. So
28:29 this is saying is internally, the nuclei can act directly on the internal
28:34 palais and tell it what to All right. So that's like me
28:42 you what to do directly, If I were to do it
28:47 I could tell you to tell her tell her to tell her to tell
28:51 what to do. You're still getting message, but it's indirect,
28:58 So the direct pathway is acting on internal Globus Pettus to tell the thalamus
29:06 tell the cortex what to do. I can do this both excitatory or
29:12 way in the, in indirect What I'm gonna do is I'm going
29:17 take something like the th uh subthalamic . So this is not in the
29:22 , it's just sitting below and I activate this system. All right.
29:26 this is acting externally to that. how do I regulate that?
29:31 I can have structures that regulate which that would be indirect. All
29:35 what else do I have up I had another structure I was looking
29:39 earlier. No, I guess I thought I did, I thought
29:45 saw something earlier. Maybe it's over . Oh yeah, here it
29:49 You know, I had a slide said this. So this is just
29:51 example. Remember, do you remember the substantia nigra is located?
29:57 but you remember what it is? the black substance, right? It's
30:01 a region in the brain stem. right. And its job is
30:05 it kind of acts as a a system to release all sorts of
30:09 to excite and to inhibit all sorts systems in the brain. So the
30:14 Nigra, for example, can activate direct pathway. So it sends a
30:19 to the basal nuclei which then goes here directly there or what it could
30:23 is it could be someplace out here activates this, which or which inhibits
30:29 , which inhibits or which activates so and so forth. So, the
30:32 here is I can go through and this basal nuclei in different ways.
30:41 not just the basal nuclei acting on motor cortex to tell you how to
30:51 . I'm gonna jump forward a couple here just for a second. We're
30:54 come back. Please do not memorize slide. This is just a visualization
31:01 show you all the different parts of brain that are involved in movement.
31:05 this isn't the complete thing. It's trying to show you. Remember if
31:09 is where um movement is being signaled your muscles. Look at all the
31:15 things that are involved. Occipital lobe through the association cortex. A on
31:20 primary frontal lobe is acting on mo cortex. We have the supplementary motor
31:25 . We have the premotor cortex, have the basal nuclei and everything is
31:31 information to all sorts of different places they're talking to each other and motor
31:36 becomes incredibly. So, do you you have to know the pathway?
31:45 do you think? Good answer. . But did you know that the
31:50 cortex is affected by the basal nuclei a direct and an indirect fashion?
31:56 . Can we say that maybe we to know some other structures involved is
32:00 thalamus involved in motor movement? What about the cere or the
32:06 Yeah. Right. Remember what are trying to do with the cerebellum?
32:10 cerebellum plays an important role to make that you're doing the right sorts of
32:15 . Like, oh, I wanna a ball. Hey, uh,
32:19 , how do I catch a Well, you need to contract
32:22 ABC D and inhibit muscles. Ef G. Ok, that's what we're
32:28 do. Oh, wait, the has changed position since I last calculated
32:32 that is. What am I supposed do? Cerebellum? Oh,
32:35 now stop doing, start doing a bit. OK. The balls moved
32:41 in the last mill since I What do I do? And that's
32:45 the cerebellum is doing. It's constantly and recalculating the kind of movements you
32:50 to be making and it's sending that up, which is what it's
32:53 it's acting and sending it through the and the thalamus is exciting the motor
32:58 and this is what you need to the motor cortex because information is constantly
33:06 . All right, I'd like to this to writing a program, you
33:11 , a computer program, but most you guys probably don't know how to
33:14 that. I don't know how to it. So I'm not gonna pretend
33:18 I know, but I've seen and . All right. Now I've looked
33:23 a computer and there's a lot of I don't know what they do and
33:25 afraid I'm gonna break everything. Now there again, the cerebellum has
33:30 organization to it. Um We have types of cells. Uh for
33:35 pini cells, these are the ones actually send information down deep. So
33:39 processing can take place within the cerebellar . Remember nuclei is where the cell
33:45 is located. And then we have fibers and here moss fibers is how
33:48 receiving information into the cerebellum so that can then send it onward. All
33:53 . So it's getting information from all of the body. All right,
33:59 get information from my muscles, What are you doing? Where are
34:03 located? I need to make calculations on what I know about you.
34:08 Spinal cord, send me information, , send me information, cerebrum,
34:14 me information. So we're processing all stuff and then what they're gonna do
34:18 they're gonna send information in different So it's gonna send it to the
34:21 nuclei. What was vestibular nuclei responsible equilibrium imbalance? We're gonna send a
34:27 nucleus. If you don't remember we're gonna get to that in just
34:29 second. All right. And we're gonna send information up to the
34:33 cortex. So the re bellum is . So structures involved so far in
34:39 include the cerebrum. We have the motor cortex, we have the premotor
34:45 , we have the association areas. have some other stuff that we haven't
34:49 . The thalamus plays a role the nuclei play a role. The brainstem
34:56 a role. The cerebellum plays a . Oh my goodness, movement is
35:03 . OK? But what we're interested is not so much. How are
35:08 working together? Just that movement involves different things? All right, so
35:14 you guys with me. OK. you can stare at this for a
35:20 . So let's get down to What are the direct and the indirect
35:24 ? This is nomenclature time. This anatomy. The direct pathways are sometimes
35:33 to as the pyramidal tracts because they originated the pyramidal cells and then they're
35:37 go down to the brain stem or the spinal cord. Now without knowing
35:41 else, why would I just want stop here in the brain stem?
35:49 , from two neurons. So why I stop here? Is there any
35:55 of movement that I would be doing this level? I don't know.
36:15 , you got it. See if rest of you get it. Facial
36:26 . Are those skeletal muscles? Do want to sit him down and then
36:30 back up again? No. So stopping here so we can control
36:39 Anyone here able to move your wiggle ears. I can't do
36:46 I know there are people here that . So just looking around.
36:49 no one's no one's gonna, that's a special skill. That's something you
36:53 on your resume can wiggle ears. . OK. All right. We
36:59 down to the spinal cord because we're dealing with the rest of the
37:02 We have two tracks, corticospinal. do you think that one's going to
37:10 and then cortical bulbar? All Now, I told you we have
37:13 different things. Brain stem or So, what do you think bulb
37:17 projecting to brain stem? Yeah, that simple. All right. It's
37:22 bulbar regions of the brain is I don't know why they call it
37:25 . All right. So we're gonna first at the cortical spinal tract.
37:30 when you look at this, you all these jelly beans and it gets
37:32 , really scary. But the only beans we're interested in are the jelly
37:36 that are listed underneath the pyramidal Oops, sorry, let's do this
37:42 . It's these two right there. is called the lateral one is called
37:46 ventral cortical spinal tract. So it tells you where it's located. The
37:53 giant pink jelly bean is the latter . The little tiny green jelly bean
37:57 the ventral one. It's located in lateral funiculus if you're lateral or you're
38:02 the ventral funiculus, if you're So, so far nomenclature is pretty
38:08 . All right. Now, here's thing. These are the ones that
38:11 responsible for your movement, your skeletal . All right. So corticospinal is
38:19 really, really straightforward. Now, we're gonna do is we're gonna go
38:23 the motor cortex and we are going Decca State. So this is where
38:29 starting and we're coming here and we're Decca State and then we're going to
38:32 down like, so, and then gonna come in and exit out.
38:36 right. So that would be the when you're dealing with the uh the
38:45 VRS. What you're gonna do is gonna come down, I'm just gonna
38:49 one that we're pointing to. So gonna originate up here in the uh
38:53 cells of the cortex. You're gonna down and then what you do is
38:58 decussate in the spinal cord. So in the lateral, I'm Decca in
39:04 medulla in the ventral, I'm Decca in the spinal cord itself. And
39:09 that's when you'd come out like, that makes sense. OK. So
39:14 they cross is different, what am dealing with lateral deals with appendicular skeletal
39:20 ? Where's your appendicular skeletal muscles? and legs? Great. And then
39:26 axial skeletal muscles are ventral. So pretty straightforward, just compare
39:40 Here's that cortical bulder. All So again, upper motor, we're
39:46 be in the motor homunculus. So gonna be premotor cortex. We're coming
39:50 through, we're going through and exiting via the cranial nerves, jaw,
39:57 , pharynx, tongue, all So facial muscles, swallowing, wiggling
40:07 time, that sort of thing. there's what it's responsible for. So
40:12 are all direct. So it should pretty straightforward, so far. So
40:18 . All right, me, so . So good. That leads us
40:27 the indirect pathways also called the extra . They originate in the brain
40:33 So we already mentioned that. All . And they're going down to the
40:36 cord and they have these four different . So these are the jelly beans
40:40 here. 1234. OK. They names. All right. The names
40:46 gonna tell us exactly where they originate the brain stem and where they
40:52 All right. So we're just going look at the first one. Where
40:54 you think the vestibular spinal tract originates nuclei? Now it's gonna be brain
41:00 , but it is right. So gonna be from the vestibular nuclei.
41:04 right. What about the reticulospinal Anything have reticular reticular reticular formation?
41:14 . All right. Rubber is gonna a little bit more difficult because you
41:17 to do a little translation here. how about tectospinal? Is there a
41:21 ? Remember that? Sound like tch ? So it begins in the
41:28 So way back when I said, gotta remember I learn these structures because
41:32 gonna come back to them here. are. All right. That was
41:35 only reason I wanted you to learn so that you wouldn't be going
41:38 I don't know what these things All right. They're named for where
41:41 begin in the spinal cord or in the brain stem. All
41:44 So what do they do? with regard to the vestibular spinal
41:49 there is a lateral one and a one. All right. So
41:53 where are we beginning? Well, generically, what do they do?
41:56 play a role in balance and All right. So it tells you
42:00 the name, but they're beginning in vestibular nuclei. All right, what
42:05 gonna do is they're gonna take that from the inner ear and the cerebellum
42:09 they're gonna go down and play a in innervating your postural skeletal muscles.
42:15 right. Now, again, this just about sitting upright, it's maintaining
42:21 posture, depend upon activity and what trying to accomplish. Right?
42:27 if you feel yourself tipping over, acting in a way where you don't
42:32 to think about, oh, I'm over. I'm going to bring myself
42:34 up. They're naturally moving your body the position that your brain wants it
42:40 be in. Ok. So it's automatic response. It's a subconscious
42:46 but it requires skeletal muscle to do . All right. I mean,
42:53 now, can you feel yourself how sitting in the chair now?
42:57 You kind of relaxed in the chair I told you to sit up,
43:02 ? Some of you will do it ? Because you've been trained by a
43:06 or an evil teacher who made you that, right? OK. Medial
43:14 going to be dealing with controlling the muscles so that your head sits still
43:20 that when you move and you're sitting , your head is not just flopping
43:26 . All right, it just holds head in upright position based upon
43:29 So when you're moving around, notice you don't walk like a pigeon,
43:33 seen how pigeons walk, right? don't walk like that, do
43:38 Right? And the reason is because hold your head up and your head
43:42 basically your brain is saying this is my vision is supposed to be
43:46 Oh OK. And I'm keeping my in the right position. You're not
43:49 around. All right. So that be balance and posture, Vullo spinal
43:56 . So the lower one uh lateral the b uh more or less
44:01 This is more or less head, head and it kind of matches
44:06 So at that, we discussed, right, reticular spinal tract. So
44:12 is a reticular formation. So this gonna play a role again in
44:17 but primarily locomotion and reflexive movement. right. Um In terms of what
44:23 want you to know here is that are primarily muscles of that are extensors
44:31 you're innervating here. All right. we have the medial, one lateral
44:36 they originate in different areas. One poke, one is medullary, but
44:40 just referred to them as medial and now. And so what we're dealing
44:45 is this is a, um, for the most part. So let's
44:50 put that excitatory and then the lateral mostly inhibitory and I have it there
44:57 I can just success. So, Tori Tori there, I'll spell it
45:01 . Uh, handwriting is awful. be a little bit cleaner.
45:19 So aols ponds laterals, medulla, , inhibitory reflect the best move.
45:26 , if I am dealing with should I still with flex ex,
45:30 , deal with flexors as well? do you think? Yeah. And
45:34 that's what the rubrospinal tract is. , they originate in the red
45:42 Rub means red or ruddy. So referring to that region. All
45:50 So here we're dealing with flexion. again, red nucleus, we're going
45:55 Decca immediately and then go on down then down to the ventral and then
46:00 to those flexor muscles. OK. the last one tectospinal tract,
46:12 we went through this stuff quick Now, you're all regretting getting up
46:18 early. Me too. All So with regard to the tech
46:24 it's going to be in the that's where it originates. So here
46:29 see tectum and what we're gonna do we are uh gonna be primarily dealing
46:36 moving heads in response to visual All right. So visual stimuli would
46:43 I see something and so I'm going move my head as I follow
46:47 Just think tennis court, right? ever go to a tennis match.
46:55 . Follow the ball. I had friend who was a pro at uh
47:05 Oaks. He always let me go the clay court games. Got me
47:09 all the time. Tennis is much fun to play than to watch.
47:14 , anyway, so that's primarily what doing is, is moving your head
47:18 regarding the visual stimuli. All Um The last little bit here
47:24 is I think just some stuff I to wrap up. We have things
47:28 cpgscpgs are central pattern generators. A pattern generator is that thing which is
47:35 to combine both uh reflexive activity as as somatic activity. And so when
47:41 walk, for example, that would creating a reflexive pattern, but it
47:47 actually some voluntary motor movement, So it takes initiation, but once
47:53 begin the process, it happens, ? It's just a repeated action.
47:58 is another example. Um Have you once you start chewing? Do I
48:01 gum? Yeah. Yeah, that's this is in high school, you
48:05 chew all the gum you want you can come with a big old
48:07 of gum, right? But the is like once you start chewing,
48:11 like, hm hm hm hm I just keep chewing. That's why
48:15 gum is so awesome. All you're basically mashing something based on the
48:19 in your mouth, but you'll just that process going because the gum kind
48:24 serves as like a, an oral and it's basically AC PG that's,
48:29 causing that reflexive response. Breathing is reflexive response as well. Basically,
48:35 you're gonna do is breathe in and you, you create that pattern of
48:40 action and then exhale and then you repeat it over and over again.
48:45 don't have to sit there and it's an automatic response but it is
48:49 muscle blinking, right? Is a reflect is, is a automatic
48:56 It's AC PG as well. All . So really what this is
49:00 I don't know if I even show the picture, but basically, it's
49:03 cyclical pattern and it's basically a timing . And so what you'd have is
49:07 have a network of say uh innovation the sensors and flex. And so
49:12 you're doing is you're exciting one and the other and then once uh the
49:18 gets strong enough, it actually flips around so that you could keep moving
49:22 the two points. And so here have a picture of a cat.
49:26 you ever watch a cat walk, always struts. Right. Exactly.
49:30 And so what you can see here you watch, you'd see,
49:33 I'm basically flipping the response between the and flexors over and over and over
49:40 and you do the same thing, . That's what walking is. All
49:45 . So where do these cpgs It's primarily in the brain stem and
49:49 also there's some in the higher cortex now we're gonna get back to that
49:56 thing. I haven't talked about the tendon reflex or the muscle spindle
50:02 Have I? Cause I used to it in unit two or unit
50:08 But I wanna make sure I haven't about it before. Right? I
50:11 back and looked at my notes. didn't see it in there. I
50:13 to actually te teach it twice. right. So what we're gonna do
50:17 we're going to deal with this stretch and what is called the Golgi tin
50:21 reflex? All right. So here are, we're looking at that motor
50:26 , right? You see the two neurons going down, there's the alpha
50:29 the gammas, there's your extrafusal. can see where the connective tissue
50:33 You can see the intrafusal on the . What we're doing is we are
50:37 the inter fusil fiber. And what asking is, is, are we
50:41 the muscle in the right place? . Now, what I used to
50:45 um in here is I would bring my big £12 book cause I have
50:50 big old £12 book and I'd have come up here and stand and I'd
50:53 them hold it out here like right. And I'd say imagine holding
50:57 £12 book. Usually I'd find the guy in the class cause the,
51:01 the f fun ones to tease. . So, imagine holding that £12
51:04 . Would your arm get tired holding out? You know. Right.
51:07 so your arm would begin slipping, . But what if I told you
51:11 you're holding that book out that I kill you. If you drop that
51:14 or lower your arm right? you have an incentive to keep it
51:18 there. Right. And so you imagine a gun to your head,
51:22 to hold the book out. All . Now, how do I know
51:25 my arm, if my arm is the right place? Well, it's
51:29 the response of this stretch reflex. right. So when I move my
51:33 out, I am contracting the muscles a specific uh degree of tension.
51:39 I, and that tension is there make sure that the arm is in
51:42 right position, right? But as get tired, the amount of tension
51:47 I'm going to produce is gonna right? Would you agree with
51:51 And so how do I know that tension has changed? Well, if
51:54 extrafusal muscle fibers are primarily responsible for the tension, even though the intrafusal
52:01 involved, it's the intrafusal muscles that innervated and they're detecting the degree of
52:08 in that. Ok. So both them are stretching and contracting to create
52:14 degree of tension, but I'm only inside the intrafusal. All right.
52:18 that's what this is trying to show is that innervation? Now, if
52:23 flip the slide over here. All . So if I detect by those
52:30 , that afer neuron that there is in the amount of stretch. In
52:35 words, that book is getting too for me and my arm begins to
52:40 . I'm gonna feel or I'm gonna that intrafusal fiber stretching more than it
52:47 that where I set it. And signal is then going to travel up
52:53 that spinal nerve through the dorsal horn then it's going to terminate on to
52:59 alpha fibers. And it's gonna hey, you're being overstretched, you
53:06 to produce more tension. You see we're doing here. So as my
53:11 begins to fall, I detect it the intrafusal fibers and IC cause a
53:17 . That's a reflex in the This is your stretch reflex.
53:23 you can see this, right? again, if I had you hold
53:26 book out here, that's not a thing, right? If I say
53:30 , I'm not gonna put a gun your head this time and I give
53:32 a book and I put that book top and you're like, OK,
53:35 not a problem. But I take book right? And make sure your
53:38 books out and put another book on . What's gonna happen to your
53:42 It's gonna go down and then what you do? You bring it right
53:45 up, right. So that is reflex that you're seeing in action and
53:49 can keep stacking books, stacking stacking books, and each time you
53:52 another book you'd see the kind of it dip down and then I'd bring
53:56 right back up again. That would the stretch reflex. All right.
54:00 , what it's doing is it's ensuring my muscles are being positioned as I
54:05 planned. So the reflex is taking at the level of the spinal
54:09 but the plan of contraction is taking where a pot right cortex. The
54:20 type of reflex that deals with movement the Golgi tendon reflex. We talked
54:26 muscles, muscles have at their We have tendons. OK. Now
54:34 , imagine here I am holding these and I started stacking those books on
54:38 , stacking the books on top. I'm gonna get to a point where
54:41 book or the books weigh more than can hold, right. And so
54:47 when a muscle contracts, what is doing? It's pulling on that
54:51 And so it causes the tendon to first a little bit to give and
54:55 it pulls on the bone, And so if I keep pulling and
55:00 on that tendon, and I keep more and more tension on that
55:05 right? And there there's greater weight the bone. So the bone is
55:08 the other way and the muscle is this way what's happening in that
55:13 It's stretching more and more and there's be a point where I put too
55:16 tension on what's gonna happen. It's tear or rip. Right. Is
55:21 ever happened to anybody here? you, you, you have
55:26 Yeah, it's a lot of isn't it? Yeah. High school
55:30 weights thought I was so cool right in the pack. Yeah, it
55:36 so much fun. All right. protects against that. So what it
55:43 is it's measuring the degree of stretch the tendon. All right. And
55:49 , notice it's not telling the you know, the muscle to contract
55:55 . It's just saying, ok, building up, I'm building up tension
55:57 when the tension becomes too high, says I need to protect the
56:03 And so it sends an inhibitory signal that muscle and says, stop
56:09 So here I am holding my keep stacking the books, stacking the
56:12 , the weight gets too much. do I do? The muscle
56:16 I drop the books. I protect muscle. Ok. So it's an
56:24 reflex to ensure that the muscle gets doesn't get harmed. All right.
56:33 , not too bad. We're done . This is uh the motor
56:37 So just to, before we go out of here you go and get
56:41 coffee for the morning, I want kind of give you the big overview
56:44 what we looked at so far, in this unit, we've looked at
56:48 coming in that sensory information, So that's how we, we looked
56:53 the sensory pathways, we looked at special senses. And then now we're
56:58 at that information as it comes that's what the motor pathways are.
57:02 it's really easy to remember those two just sent versus motor. OK.
57:07 last thing we're gonna do when we back after Thanksgiving, we remember we
57:10 a lecture on Tuesday again. because this is just how the schedule
57:16 . And then we have a Our last test. Nothing else on
57:21 Thursday. Ok. So I want to go home. I want you
57:26 enjoy your Thanksgiving. All right. , that's your job. That's,
57:32 don't expect you to study. I even the homework for, for today
57:36 close until Sunday, right? So the idea is you can get it
57:41 tomorrow if you want to, but have until Sunday to get it
57:45 But when we come back, it's class. Last exam we're done.
57:53 ? And we're gonna talk about the nervous system. I've been talking about
57:56 or mentioning it over and over and again all semester. Finally get into
58:00 . Have a great day and a Thanksgiving. Eat lots of turkey for
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