what's up ninja nerds in this video today we're going to be talking about stroke syndromes before we get started though please the most amazing way that you can continue to support us to make these awesome videos for you guys is to hit that like button comment down in the comment section and please subscribe also if you guys want to follow along with this comprehensive lecture on stroke syndromes we'll have a link go click on that check out the notes and the illustrations that we have available to you guys all right ninja nerds let's get into it alright so let's talk about stroke syndromes why do we need to know stroke syndromes well the basic thing is that when someone comes in with an ischemic stroke or a hemorrhagic stroke they're going to present with particular neurodeficits dependent upon that vascular territory that gets hit and so we need to know what vessel supplies pretty much what area of the brain or brain stem and if that is affected what types of clinical manifestations will be evident i think that's pretty much it so let's start off talking about the mca syndrome or middle cerebral artery syndrome so briefly we need to say middle cerebral artery what parts of the brain does it supply that'd be a nice little kind of get you know thing to start off with i think the best way to look at it is this tiny little diagram here in green the green is representative of the mca division so the mca division you have supplying the frontal lobe here you have it supplying part of the parietal lobe and you even have it supplying part of the temporal lobe okay so that's a really important thing to remember supplies good chunk of the brain frontal lobe parietal lobe temporal lobe another big thing to remember is it supplies more of the lateral side of the parietal lobe in the frontal lobe okay big thing to remember so let's talk about first some of the frontal lobe things so if we take a slice of the brain in a coronal section and we take that slice just in front of the central sulcus okay just in front of it we're going to be looking at the frontal lobe now in a coronal section so imagine there's our coronal section on one side i'm representing kind of the vascular territory so here's going to be the frontal lobe here this little bump there is a part of the temporal lobe the frontal lobe in the medial portion is supplied by the anterior cerebral artery this cold chunk here the lateral portion of the frontal lobe is the mca and even a little bit of the temporal lobe is mca and just that bottom portion there is the pca in blue when someone develops a middle cerebral artery stroke and they knock out a particular area in that frontal lobe if you guys look here in this side view here here this in black is the central sulcus in front of it here is your primary motor cortex that's where the voluntary movement of skeletal muscles occur if you knock out the mca and you don't supply blood flow to that primary motor cortex what happens well you can't move the opposite the contralateral side of the body so for example let's take for example here here's your right mca division and let's say that you knock out this portion here where these little red neurons are so if we follow these red neurons from the right primary motor cortex they'll come down corona radiata internal capsule through the crust cerebri through the pawns decasade at the pyramids go down to the spinal cord and supply the muscles on the left side you knock these out you develop weakness on the left side but here's where we've got to be really specific you guys really need to remember your frontal lobe anatomy and function what we take the slice there's they like to put that little man there called the homunculus right little motor homunculus it tells you what parts of the body this portion of the brain supplies if we take a look here i want it really basic face upper extremities lateral portion of that motor cortex lower extremities medial portion of that motor cortex so when you knock out the mca kind of match it up there i'm getting face and upper extremities way more than i'm going to get any lower extremity involvement boom contralateral hemiplegia so paralysis of the face upper extremity way more than the lower extremity boom roasted move on to the next thing let's take a slice let's take it imagine it's going to be the same drawing take a slice a little bit farther back now we're going to go behind the central sulcus we go behind the central sulcus here's that black line there's our central sulcus we have a blue strip here that's our sensory strip that's our primary somatosensory cortex imagine you knocked that bad boy out what's going to happen well it's going to lead to sensory loss on the contralateral side what kind of sensations all of them it could be touch pain temperature proprioception vibration all of them you lose those on the contralateral side let's make sense of it imagine here's some skin and that's where there's some touching occurring no no don't be weird about it this information comes up via either the dorsal column if it's kind of like your fine discriminative touch or if it's like your crew touch maybe via the spinothalamic system it'll come up cross over and go if it's coming from the left skin of the left side of the body it'll go to the brain on the right side okay now you develop an infarct within the mca or some type of lesion of the mca knocks out that portion you lose sensation to the contralateral side of the body again same thing sensory homunculus lower extremities supplied more particularly immediately by the aca and then laterally is going to be the mca that's your face and upper extremities so you get contralateral sensory loss involving what face upper extremities more than lower extremities really quickly here i mentioned that there's two divisions the superior division and there's an inferior division of the mca really really briefly if you kind of imagined here let's do it in a super bright color here pink when the mca kind of tucks underneath this lateral sulcus it kind of comes out from the lateral sulcus and gives a branch off here and gives a branch off there okay this branch here is called the inferior division this branch here is called your superior division the superior division of the mca is what supplies that primary motor cortex and primary somatosensory cortex so if you injure that vessel that superior division it affects these territories it wouldn't be affected if you hit the inferior division of the mca okay so remember that all right let's move on to the next thing contralateral weakness sensory loss boom face upper extremity more than lowers next thing is the frontal eye fields okay same thing take a side view of the brain here you have that black strip what is that called that's your central sulcus in front of it you have the motor strip primary motor we already talked about that one behind it you got the primary somatosensory already talked about that one then a little bit more interior what do you have a little pink dot there is called your frontal eye fields your frontal eye fields still fall within that green the territory of the mca if you want to be specific to what division it'd be the superior division right of the mca that's getting hit particularly leading to this lesion in the frontal line fields all right so we have an idea that the frontal eye fields is still supplied by the superior division of the mca we know that it's in the frontal lobe what happens though if it gets knocked out we have to briefly and i mean briefly talk about what the heck it does frontal eye fields let's say that we take a coronal section where the frontal eye fields would be and here we have that kind of view frontal eye fields let's say that we have the right side so let's say here's your right frontal eye field it'll send these axons down to a structure here in your pawns here an orange the left one called the pprf the left paramedian pontine reticular formation stimulates that guy that guy when he's stimulated he then tells this blue neuron called your six nerve nucleus hey buddy go ahead and fire and tell that lateral rectus muscle to contract and when it contracts it's gonna abduct the eye outwards okay oh cool i'll do that for you also why don't you tell the third nerve because you know you're connected to the other third nerve via what's called the medial longitudinal fasciculus so tell that right third nerve hey buddy go ahead and fire for me and when you fire tell that medial rectus to go ahead and pull your eyes that way as well so generally what should happen is when the right frontal eye field fires your eyes deviate to the left what do you think would happen though if you knock out that right frontal eye field do you think your eyes will be able to deviate to that left side or gaze to that left side no what happens is if this left side is working fine and properly and it's doing everything it needs to do it's good the left side is going to tell the eyes to be to the right normally there's nothing that's interfering with that so it'll be unopposed now by this damaged right frontal eye field and guess where the eyes will start to preferentially deviate naturally at rest to the right side the same side as where the lesion is so we call that ipsilateral gaze deviation okay sometimes they even call it a gaze preference so it's because you're knocking out that frontal eye field if it's on the right your eyes will deviate to the right boom roasted onto the next one the next area here is called your wernicke's area workies area is a really cool area so it helps us to comprehend understand language if you will so language can be written it can be spoken it can be non-verbal and so a lot of that stuff can be picked up from two particular sensations if i'm speaking to you and you guys are hearing my voice that's hitting your auditory cortex when it hits your auditory cortex it sends that information to warnicky's area right from your primary auditory cortex you also see me writing things down you see me drawing arrows and referring to things and giving you non-verbal cues right so that information from the occipital lobe from your visual cortex will also get sent to the wernicke's area the wernicke's area will then take that information about language analyze it recognize it and help us to comprehend what is being spoken or written if you develop a lesion within the mca but we got to be very very particular think about that that kind of blood flow again we'll do it in green since that was kind of what we were trying to indicate with the mca it sneaks up under the lateral sulcus or the sylvian fissure gives off this division and then gives off this one what division do you think it's going to get hit the inferior division so inferior division of the mca if it gets hit can lead to the wernicke's area becoming affected if it's affected can you comprehend language no so comprehension of language is gone the other thing that happens is that wernicke's area loves to communicate with this blue area in the frontal lobe called broca's area tells broca's area hey buddy i understand language can you tell them what you actually understand so then you would tell broca's area broca's area controls the muscles of the speech which allows for the production of language expression of language so in someone who's wernicke's aphasia they can express language properly and fluently but because they can't comprehend language it literally makes no sense it's nonsensical and so that is important to remember with wernicke's area leading to if there is an mca lesion wernicke's aphasia what we particularly like to call it though is receptive aphasia okay boom roasted move on to the next one broca's area you guys are probably already picking this up because you guys are so darn smart but again same thing mca kind of sneaks under right so you have that kind of like that m1 m2 segment that sneaks over here particularly m2 segment segment and then branches there there and then there if we have broca's area which is going to be this little blue little dude right here if we knock that out that falls within what division the superior division of the mca so if we hit the superior division of the mca that could lead to the damage to broca's area what does broca's area do we already kind of introduced that already receives information from the wernicke's area as well as other areas other motor areas and helps for the production of speech enables particular types of cranial nerves cranial nerves five cranial nerves uh seven cranial nerves uh ten and nine and all of these in twelve and helps for the production of speech in a particular way if broca's area is affected speech will no longer be fluent and it won't be able to be expressed properly even though you can comprehend language and understand what everybody's saying or what you're reading you just can't express it properly and so that's what happens with broca's area being damaged leading to what's called broca's aphasia next thing is the optic radiations okay so a little another little diagram here if you will so imagine here we have a little baby diagram and again you have that mca sneaking underneath the sylvian fissure and it gives off this one and then it gives off this one right well you have these things called optic radiations optic radiations kind of like to move through the parietal lobe and the temporal lobe okay and so what happens is when someone develops a mca lesion if you will that's knocking what part the inferior division of the mca it can affect the optic radiations that are moving through the temporal lobe and even a little bit through the parietal lobe so if that happens you can lead to a particular visual dysfunction because optic radiations you can already get from the word optic radiation that's something to do with the visual pathway we'll briefly explain this but if you knock out the inferior part of the mca it can lead to some visual pathway dysfunction let's briefly explain what the heck i mean so let's say here we have a portion of that like here's your optic radiations right here after the thalamus going back to the occipital lobe right here that's all optic radiations if someone develops an mca infarct or an mca lesion that leads to an infarct of this territory here where the optic radiations are running through whether that be through the temporal lobe whether that be through the parietal lobe whatever that inferior mca division is getting hit that knocks out these optic radiations let's follow the optic radiations backwards to the eyeball and see what type of visual information they're picking up so for example if we follow this blue one back here boom you hit on this part of the retina remember that this part of the retina picks up visual information from this visual field okay then if we follow the maroon one back the maroon one boom this is going to be this part of the retina kind of towards the nasal part of the retina again remember this picks up visual information from this part of the visual field okay so if we kind of recap here this is if we look at this let's say that this is the right side of the brain and this is the left half of the brain okay if you develop a lesion within the inferior division of the mca you knock out the optic radiations on the left side what happens to your visual field loss well you lose the visual fields on the contralateral side the right visual fields and so if i knock out my right visual fields that's the contralateral side of where the lesion is but they're kind of similar so we call that contralateral homonymous hemianopia so if you have a left-sided mca infarct on that inferior division you've not got those left optic radiations you won't be able to see the visual fields on your right side let's move on to the last part here which is the mca division particularly on the right side so i didn't preface this before so broca's area wernicke's area they're primarily on the dominant side okay and the dominant side of your brain is usually the left side since most people are right hand dominant so the left side of their brain is where the broca's area and wernicke's area reside so if i knock out the left mca i'm going to potentially see these two symptoms if i knock out the right mca it's unlikely that i'll see these two symptoms i'll actually see these particular symptoms present okay so what could i see if i knocked out that right mca okay for the non-dominant hemisphere primarily you see two particular things that i want you to remember apraxia and hemineglect apraxia is very interesting it's where you your motor system is intact so your muscles are fine there's no issue there you have the willingness to want to perform a motor movement but you just can't figure out how to do it so there's a difficulty in being able to actually act out that movement even though you are and willing to do it examples of these is idiomotory apraxia for example hey can you lift up your right arm instead of them lifting up their right arm they'll do something weird and maybe they'll just give like two fingers or if you tell them give me a thumbs up they'll give you two fingers they start mixing up their movements and kind of don't really know how to really perform the movements properly eye little practice is very common where you ask them hey open up your eyes there's nothing wrong with the levator palpable superiors it's working fine it can contract and elevate the eyelid and they want to do it they just don't know how to do it and then ideationally practice it give them a marker and say hey draw me something they'll look at this and they'll be like dang i know this is a marker and i want to draw something but i don't know how to use this dang thing and that's ideational apraxia so that's again recapping it motor functions intact willingness to do the function is is okay but they just don't know how to do it or kind of really go about performing that activity neglect is also very interesting so again you not got that right mca which is usually the non-dominant side you neglect the sensations on the contralateral side of the body just like you would if you knocked out your primary motor primary sensory cortex whatever the same concept for example knock out my right mca if i have hemi neglect you let's say that you have a patient you're going into the room you have three people in the room one here in front of them one here on the right of them and then one over here to the left of them and let's say that you ask you ask the patient hey how many people are in the room they will see the person in front of them they will see the person to the right of them but they will not be able to see the person in their left visual field because they're neglecting their left visual field so that's an example of one the other thing here is sensory if you take and have the patient close their eyes and then you say okay i want you to tell me which side of your body i'm touching and you touch both of the sides simultaneously they'll say oh you're only touching my right side you want to know why because they're neglecting all of the sensations on the left side of their body and so that's what can happen with right mca infarcts usually referring to it as the non-dominant hemisphere okay that tells us what we need to know about mca syndrome which is the most important one let's now talk about aca syndrome all right ninjas so let's talk about aca syndrome so aca syndrome anterior cerebral artery syndrome you knock out one of those acas so aca is going to supply pretty much what part of the brain so it supplies primarily the medial frontal lobe and the medial parietal lobe okay it even hits a little bit of basal ganglia as well parts of it so what i really want us to focus on is it's kind of similar to what we talked about with the mca in the beginning the primary motor and primary somatosensory cortex this should actually be a very quick recap we shouldn't have to spend tons of time is that if we take a look here at the side view of the brain here's going to be our central sulcus right here and then in front of it is the primary motor cortex right if we draw here in pink what portion is actually aca it's kind of kind of be like this if you really want to think about it that's all going to be the aca and then if we had here before just to kind of like in a dashed line here what was this part here that was the mca right so when we're talking about the kind of the different territories here the aca is hitting more of that medial strip of the primary motor and primary somatosensory cortex whereas that mc is hitting more of the lateral portion so what do you guys think do we really even need to go too hard here let's briefly blow through it here if we take a coronal section in front of the central sulcus where the primary motor cortex would be upper motor neurons are going to come down be the corona radiata internal capsule cross cerebri through the pons decasate at the pyramids come down the lower motor rounds and go to the muscles on the contralateral side you develop a lesion in the aca particularly the medial territory you knock this out you develop weakness on the contralateral side but what does the hemoder homunculus tell you for mca it was face upper extremities as represented here in green for aca it's pink here which is lower chemist you're knocking out lowers more than the uppers and the face boom roasted what about the blue stuff here go back take another section imagine that this is another section and we're taking it behind the central sulcus where the primary somatosensory cortex is where sensations are basically involved we take these sensations coming from the skin coming up maybe dorsal column may be spinal thalamic tract and eventually going from the left side of the body to the right cerebral hemisphere if you develop a lesion in the aca you knock out the sensations coming from this portion contralateral sensory loss again remember your sensory homunculus for the face and upper extremities that was the mca territory but for lower extremities that was primarily aca territory represented in pink so you get contralateral sensory loss involving what lowers more than uppers and the face boom rose too we just did it right we blasted through that pretty quickly now move on to the next one so the next part is the paracentral lobule the paracentral lobule is a very interesting little thing imagine here for a second we were taking a look at the brain from the side right imagine i cut it in a sagittal section and i removed that right piece so now you're just looking at the left half of my brain from the medial side so here's that view here you see like your corpus callosum here and then above it in this pink kind of structure there is what's called the paracentral lobule the paracentral lobule is interesting because it kind of picks up sensory and motor information so there's kind of going to be like some sensory information here that comes to the paracentral lobule and there's also motor information that is involved and connected from the paracentral lobule to the urinary bladder in some parts of the bowels but big one to remember the urinary bladder if you knock out the paracentral lobule from an aca and fork because again you're falling within that kind of like medial strip of the aca this is all aca right here so if i were to kind of highlight here this is all aca if you knock out that paracentral lobule you no longer have proper sensory and motor function of the urinary bladder and but maybe somewhat of the bowels too so there is what's happening of urinary incontinence and fecal incontinence so you accidentally go pp or so that is the basic concept of the paracentral lobby so we got contralateral weakness contralateral sensory loss more particularly lowers than uppers and we got urinary fecal incontinence if you hit that paracentral lobule the other thing that we should remember here is again take another medial view of that cerebral hemisphere and we're looking at that left cerebral hemisphere it also can hit another portion here so if we kind of again and pink here all of this would get hit from a aca lesion okay what are these two areas that i want you guys to think about these are particularly more for behavior okay behavior decision making things like that so we have here in green the prefrontal cortex you guys know that prefrontal cortex is involved in tons of things emotions memories decision making personality behavior executive function all that stuff the anterior cingulate cortex is kind of involved with also aspects of memory but a part of our limbic system so whenever you knock out these two structures it leads to particular behavioral and decision-making abnormalities and we kind of classify these as a boolea and akinetic mutism so ebulia is basically they have a significant decrease in motivation willingness any desire to want to do anything purposeful like verbally or or motor example you come into the room you say hey miss jones can you please lift up your left arm there'll be a very significant delay and kind of a very decreased desire to want to lift up her arm if she even does hey can you tell me where you are what's your name there'll be a significant delay if even if she does respond to what's your name or where you are so because there's this decreased willingness desire and motivation to want to interact or perform verbal or motor activities that's a boolea if you knock out these two structures if you knock out both of them because you get a bilateral aca lesion you get even worse you get to the point where you don't talk and you don't move because you have no desire no willingness no willpower to want to interact verbally or motor via a kinetic no movement mutism no verbal communication all right so the next part here of the aca syndrome is if you hit like a in again we're adding this in just a real quick little thing is that there's this little red area remember i told you that the broca's area can receive information from wernicke's and it can receive it from another motor area particularly within the frontal lobe and so this little red area within the anterior superior frontal lobe communicates with the broca's area and it's involved in speech okay if you develop an aca lesion particularly in that dominant hemisphere that left side primarily usually right you're going to knock out this structure here and its connection to the broca's area and so what happens is is you develop again a some difficulty with speech production so because it's responsible for communicating with broca's area there is going to be some difficulty in telling the broca's area to be able to engage in speech engage in expression of speech so there will be some non-fluent or decreased speech ability but comprehension will be intact same like uh broca's area because why why should comprehension be intact for both of this red and this blue thing are you touching wernicke's area no so since wernicke's area isn't getting involved comprehension should be intact so asking them hey what's this called oh it's a marker oh uh what's if i pull out my phone what's this called oh it's a phone now here's where it can be a little bit different between broca's and blue and red for this transcortical motor aphasia if you say hey can you repeat after me no ifs ands or buts or today is a bright and sunny day and they can do that that is indicative of transcortical motor aphasia if they can't do that it's indicative of broca's aphasia so you can still get aphasia from aca syndrome but remember if it's transcortical motor aphasia you can differentiate it from broca's by asking them to repeat phrases if they can it's transcortical motor unlikely for it to be broca's okay that covers our aca syndrome what do i really want to do next before we go on to the next thing called the ica i want to talk about this thing called watershed zones we talk about this in acute ischemic strokes called watershed infarcts that can happen from global hypoperfusion you remember uh kind of like if you take a top look at the brain right take a top look at it and here we have the frontal lobe and you can represent that it's frontal lobe because here is anterior here's posterior here's your central sulcus okay in front of the central sulcus is going to be the frontal lobe behind the central sulcus is parietal lobe here remember what i told you the lateral portion of the frontal and parietal lobe is supplied by green which one mca right so this is all mca and then the medial portion of the frontal and parietal lobe is supplied by the aca where they meet here in red is called that watershed zone and those zones are really kind of susceptible to high to very low perfusion so if you drop their perfusion to these particular areas they're very susceptible and the neurons and brain tissue in that zone can become damaged what happens then is you start to kind of fall within that category remember here we have like lower extremities and then over here we have like face um and upper extremities and then somewhere here in between is kind of like your trunk and like the proximal extremities of the lower proximal lower extremities proximal upper extremities you're kind of going to be falling right within that part of the trunk at the proximal extremities upper and proximal lower extremities and so because of that when someone gets a infarct of that watershed zone in the mcaaca territory you knock out that proximal upper extremities and proximal lower extremities but again think about this if you hit frontal lobe where that primary motor strip is what would happen you develop weakness right and it can cause contralateral weakness or contralateral hemiplegia if you knock out the parietal part where the primary somatosensory cortex is what do you get you get sensory loss of the contralateral side as well so again big thing to think about with watershed zone particularly mcaca if you knock that out you develop proximal upper extremity weakness and sensory loss proximal lower extremity weakness and sensory loss and we also call this man in a barrel syndrome okay so that covers mcaaca watershed zone as well as the mcaca syndromes let's move on to ica syndrome all right so we talked about aca we talked about mca we talked about the mcaca watershed zone let's talk about the ica and actually nicely this would be a good quick recap of the mca and aca because the ica is a very large vessel and what happens if you guys remember your circle of willis blood flow it comes up and branches into the aca and mca and also there's another little vessel that i'll talk about really quickly called the ophthalmic artery so if we kind of take a look here again coronal section looking at the brain here and again you got your let's just say here you have the the frontal lobe and then here you have your your temporal lobe here that in that circle there this circle is representing the ica this is coming up and feeding the circle wheels the anterior circulation of the circle oils and what happens is it gives off this one that's moving towards this actual portion here towards the medial portion and we'll supply the medial portion of the frontal prior lobe this is called your aca and then you're giving off this other portion here which is going to feed laterally through that lateral sulcus sylvian fissure come out and give off the superior inferior divisions that will supply the lateral portion of the frontal lobe parietal lobe and the temporal lobe what is that that's your mca if you develop an occlusion or injury or damage of the ica you could potentially lead to a decreased or no blood flow via the aca or decrease no blood flow via the mca so what could happen is you could present with an mca syndrome let's test your knowledge contralateral hemiplegia contralateral sensory loss where face uppers more than lowers frontal eye fields what happens you get ipsilateral gaze deviation you hit wernicke's you get warning keys aphasia you hit broca's you get broca's aphasia you hit the right non-dominant side you get apraxia hemi neglect and if you hit those optic radiations you get contralateral homonymous hemianopia aca you get contralateral hemiplegia contralateral sensory loss of what lowers more than the face in the uppers if you also hit the paracentral lobby you get urinary fecal incontinence if you also on top of that hit the prefrontal cortex of the anterior cingulate gyrus you get a boolean a kinetic mutasm and if you hit that motor connection between the broca's you get transcortical motor aphasia we just recap those now that's ica if you get a severe enough damage to it now one other thing the pca is primarily a posterior circulation vessel comes off that vertebra basilar system and five percent of patients they may have what's called a fetal pca variant so be aware of that sometimes you can actually have an orange here that pca come off of the internal carotid artery rather than it come off the vertebral basilar system so if someone also develops post hair circulation stroke like pca division which we'll talk about here and you think that they have a problem with their ica think about that fetal pca variant the last thing i want to talk about with ica is the ica also affects this vessel so here's your ica and it gives off a vessel called the ophthalmic artery which will help to feed the central retina artery some of the ciliary arteries that supplies the retina if you have a decreased blood flow to the ica okay and then into the the ophthalmic artery essential retinal arteries you can develop this transient type of mono-ocular vision loss so for example right ica right transient monoocular vision loss and that's called amaurosis fugax if it is not reversed or treated then what can happen this can become complete damage to the retina and complete monoocular vision loss so that's another thing to think about with ica if they develop mca syndrome aca syndrome plus or minus pca syndrome if they have that fetal pca variant and transient ipsilateral monoocular vision loss think about ica syndrome all right so we talked about the mca we talked about the aca we talked about the ica we even talked a little bit about the mcaca watershed zone so we haven't talked just yet about the pca we've kind of introduced it the posterior cerebral artery but there's another watershed zone that i want to talk about before we start going into the post-air circulation so that stroke syndromes so this is called your mca pca watershed zone just like the aca mca think about if you take a an actual axial cut okay so you're taking an axial cut of the brain and we're going to take it to where we get part of the like frontal lobe here maybe parietal lobe and then you get back here your occipital lobe well where we get to the point of where the mca and aca territory start to come together and kind of meet one another we'll represent that here in this red color that is going to be the mca pca watershed zone just as an example here right here would be your mca aca watershed zone where we get that mana to barrel syndrome if you knock out the mca pca watershed zone what you see with global hypoperfusion because this section where they meet is very very sensitive to low blood flow or low oxygen carrying capacities you can get these watershed infarcts and it leads to visual dysfunctions two of the types that you probably want to remember the most important one is prosopagnosia so prostopagnosia is actually relatively sad what happens is the person can visually see so the primary visual cortex is intact but when you start involving kind of the association areas which you get closer to that mca pca watershed zone it starts affecting the ability to analyze recognize and identify what those objects you're seeing are or people you're seeing are for example rob is filming me right now i know that there's an object there i analyzed him i know he's there and i know that it's rob for someone who has the potential this mca pca watershed zone infarct they'll know that there's an object there but they won't be able to make out who that person is it was relatively sad the other one that can happen here is balance syndrome relatively rare but balance syndrome is kind of a triad if you will of simultagnosia so you know those little things called the ishihara color plates where they have like you know red and green and blue and whatever and it's used to like form a number within that maybe like the let the number four is in there the individual will be able to see the different colors but won't be able to see how the colors make a image such as the number four so that's called simultagnosia the other thing they can get is what's called optic ataxia which is very different from cerebellar ataxia so when you do like the finger to nose test they'll have difficulty bringing their finger from their nose to the patients to the to the clinician's finger but they won't have a problem bringing it back to their nose so it could be something like this and back here something like this back here perfectly the last part of the triad is ocular motor apraxia where they just have again motor the all the ocular extraction muscles are moving functionally they're intact they have the willingness to move their eyes but they just can't execute the movement or they don't know how to be able to move their eyes in kind of a horizontal fashion so it's called ocular motor apraxia i think it gives us a good idea pretty much of kind of talking about our anterior circulation strokes as we start to transition into our posterior circulation stroke syndromes so let's briefly talk about these recapping anterior circulation stroke syndromes we talked about anterior cerebral middle cerebral internal carotid and we also talked about that mca aca watershed zone and we briefly started to get into that mca pca watershed zone anti-circulation strokes are by far the most common 70 of strokes poster circulation which we're going to talk about now is getting towards like the occipital and brain stem area this is covered by the posterior cerebral artery the basilar artery and the vertebrate and these account for the 30 of stroke syndromes that we're going to talk about now so let's go ahead and now focus on posterior circulation strokes starting with the pca territory all right so let's talk about the posterior circulation stroke syndrome so now we're getting into the pca the posterior cerebral artery so posterior cerebral artery really interesting one supplies a pretty decent chunk of the brain stem particularly the midbrain so we'll talk about some of the midbrain syndromes it also supplies the occipital lobe we already know that so we're going to talk about some visual defects and then it also supplies another structure called the thalamus which is very important as well all right so let's talk about the uh particularly the posterior artery so again a nice little view here i like to look at that side view just to give us a good idea here so when we look at the side view here we can see here in green is the mca territory hitting that lateral frontal parietal upper part of the temporal for the aca we're getting the medial frontal and parietal and then the pca you're getting that occipital lobe and then you're getting down here into the temporal lobe right so we know that here's where we got to talk a little bit about this first one which is if we start involving this kind of visual cortex area so you know you have what's called the primary visual cortex and the association cortex and these are responsible for taking in visual information from the optic radiations from the optic tracks all of that good stuff so if we take for example let's say here is going to be right here is going to be left this is going to be a nice quick recap of the mca here let's say that we have a infarct or a lesion of the pca that knocks out this left visual field area particularly the left visual cortex so because of that if you kind of track all of that stuff back like we did before from that side you're going to lose the visual field here on the opposite side and you're going to lose this visual field if you track all of these back so this is the left particularly like occipital lobe lesion so what's going to happen is you're going to lose your visual fields on the right side of the contralateral side so we call that contralateral homonymous hemianopia okay so that's what you would see with a lesion particularly involving the kind of your visual cortex and association cortex all right ninjas let's move on to the next part here which is the midbrain part of the pca territory right so we talked about the pca supplied the cortical part of the occipital lobe a little bit of the temporal lobe we talked about the thalamic involvement now let's talk about its extension into the brainstem particularly the midbrain there's three midbrain syndromes that i really want you to know there's actually another one too but this is the these are the three main ones i want you to take away from this if you knock out the pca so here the midbrain you got the ventral part of the midbrain so this is the anterior part here if i were to kind of denote this this is anterior part of the midbrain posterior part of the membrane okay if you knock out the midbrain there's different syndromes that can develop the first one that can happen here is if you knock out the third nerve as well as the corticospinal tract okay so if you've not got the third nerve in the cortical spinal tract that leads to what's called weber syndrome knock out the third nerve you get ipsilateral third nerve palsy because the third nerve doesn't cross the other thing is you get contralateral hemiplegia this may be somewhat confusing you're hitting your left corticospinal tract which is in the left crust cerebri you guys know what happens right uh whenever we have the corticospinal tracts starts from the cortex comes down to the corona radiata internal capsule moves through the midbrain imagine for a second here that we come down the ponds come down to the medulla what does it do when it gets to the medulla at the pyramids crosses and goes to the muscles on the contralateral side so if you knock out that left cross cerebri where again the corticospinal tracts are running you get weakness on that contralateral side and then same thing the third nerve is what supplies particularly a bunch of different muscles but one of the big things to remember here is that it's going to lead to what's called a down and kind of out movement of the eye and if you hit those parasympathetic fibers it may even cause some dilation as well all right so we got weber syndrome down third nerve palsy ipsilateral contralateral hemiplegia weber syndrome next one is claude syndrome claude syndrome as you're going at the level of the red nucleus now so here we were at a particular level we want to go for clawed syndrome go to the level of where the red nucleus is in the midbrain when you go to the level of the red nucleus you still have that third nerve there but whenever someone has clawed syndrome due to a pca lesion you knock out two particular structures one is the third nerve again if you have third nerve that's injured in this claude syndrome it's going to cause a down and out movement of the eye right it also could cause dilation if you hit the parasympathetic fibers but you're also going to hit this thing called the red nucleus what does the red nucleus do the red nucleus is a part of your rubric spinal tract right so it involves kind of like distal flexion but it also loves to communicate with your cerebellum loves to communicate with the contralateral cerebellum so if you knock out the red nucleus you knock out the communication with the contralateral cerebellum so for example if you not got that left red nucleus in this case for example this is going to be right this is going to be left if you knock out that left red nucleus you're altering the connection between that right cerebellum and the left red nucleus that's going to lead to ataxia on that side of where the cerebellum was communicating with the red nucleus so for example if it's the right cerebellum communicating with the left red nucleus you would develop ataxia on the contralateral side of the red nucleus but the same side of the cerebellum okay so we call that contralateral ataxia so again recap brief recap for claude is you hit third nerve so ipsilateral third nerve palsy you hit the red nucleus leading to contralateral ataxia because you communicate with the contralateral cerebellum okay next one is benedict syndrome benedict is basically weber and claude that's all you need to remember is weber and claude so you're knocking out the red nucleus you're knocking out the third nerve and you're knocking out those corticospinal tracts so what do you get if you've not got third nerve you get ipsilateral third nerve palsy down out movement you hit the parasympathetic dilation you hit the corticospinal tracts crosses again later at the pyramids you get contralateral hemiplegia and if you hit the red nucleus again that communicates with the contralateral cerebellum you'll get contralateral ataxia boom roasted we just hit pca syndromes let's move on to the next thing which is your basilar artery syndrome all right nigerians let's move on to the next thing which is the basilar artery syndromes so basilar artery is a beast all right so this supplies a good chunk of the brainstem particularly the pons and the cerebellum okay so we're talking about the superior anterior and inferior part of the cerebellum so again if you want to recap it what does the basilar artery supply it supplies the pawns it supplies the superior anterior and inferior part of the cerebellum and we're going to make sense of all this it's actually relatively easy so let's take a look at the quick little blood flow supply here so we have particular numbers that i want you guys to know we'll briefly recap though kind of the circulation right so here we're going to have your vertebral arteries right those come off of your what so you remember how you have your uh your brachiocephalic and that goes in for example let's say brachiocephalic goes into the uh subclavian and then it goes into the internal carotid so the common carotid so off of that kind of subclavian you can have those vessels called the vertebrals that can pop off so you have the vertebral arteries that are going to be here they'll give off a branch that we'll talk about later in the vertebral artery stroke syndromes which is called your pica eventually the vertebral arteries will come together fuse and make this big mama here this is number one number one that i want you to remember is the basilar artery it's basically from this whole chunk right here to this whole part right here is going to be our basilar artery so basilar artery supplies a very good chunk of the ponds but what i want you to really really remember is that the basilar artery gives off lots of branches the basilar artery branches that actually are going to be little branches that penetrate into the ponds the pair median branches supply primarily the medial pawn so when you guys think basilar artery its branches the immediate branches off of it is going to be the paramedium branches those supply the medial pawns another thing that happens is as the basilar artery tracks tracks track tracks up so we actually should say that the basal already comes up about here it gives off a branch here called the pca that's number two so pca is the number two branch off of the in this case the basilar artery and that's the part that we already talked about gives way to the midbrain supplies the occipital lobes temporal lobe even hits that thalamus right the other one is we move our way down so number one number two we got pca number three off the basilar artery here is this guy called the superior cerebellar artery superior cerebellar artery what do you think is implies the superior cerebellum move on to the next one so we got again vertebral's coming up basilar basilar goes all the way up gives off pca then it gives off sca then if we come down a little bit the other branch that it gives off here number four is the anterior inferior cerebellar artery that supplies the lateral portion of the pons and it supplies the anterior and inferior portion of the cerebellum thus its name quick recap again vertebrals come up fuse make basler basilar extends all the way from the ponds upwards up here branch it gives up at the top is the pca the one that it gives off underneath that is the sca and the one that it gives off underneath that is the aica or the anterior inferior cerebellar artery got it now that we know that and we know that the basilar its immediate branches give off medial ponds ica gives off lateral pons anterior inferior cerebellum sca supplies the superior cerebellum we know the big big vessels that we need to know now for the basilar artery let's talk about these now so the first thing i want you guys to remember is the basilar artery gives off a little pair of medium branches that supply the medial pons if you knock out the little paramedium branches of the basilar artery you don't give blood supply to the medial ponds you lead to neuro deficits from the destruction of all the structures in the medial pond so we need to know what in the heck is in the medial pons let's do that let's do it from dorsal to ventral from the dorsal part here kind of in the midline you have a particular nucleus and this is the sixth nerve nucleus sixth nerve nucleus is also known as the abducens nerve so abducen's nerve if you hit this so let's say here again this is kind of this blue is marking the territory you see all this blue here this is all basilar artery the paramedian branches of the basilar artery so that's all kind of encompassing this part here if you guys can imagine that if we knock out the pair medium branches we don't give blood supply to the six nerve nucleus what does the sixth nerve do it abducts the eye the same eye so if it's left abducen's nerve it's going to abduct the left eye if you knock that out you develop ipsilateral six nerve palsy can't abduct that left eye what's the next one go here to this little maroon colored one that maroon color guy is called the mlf medial longitudinal fasciculus what does it do it connects it's a midline structure that connects the third nerve at the top fourth nerve and the sixth nerve all i want you to remember is it helps to conjugate eye movement so if you want to move your eyes to the right you have to have your left medial rectus contract and you also have to have your right lateral rectus contract so that mlf helps to coordinate and conjugate movements properly with those extraocular muscles okay between what structures you're connecting three four and six if you knock that out it's going to lead to what's called internuclear abdominal plays your eyes going to be all wonky because you're not going to be able to coordinate the eye movements conjugately properly because you knocked that structure out move to the next thing as we go a little bit more anterior we got this blue structure here called the pprf the paramedium pontine reticular formation this also is involved in kind of conjugating eye movements as well so if you knock out that you develop a loss of gaze to that same side of where that pair medium pontine reticular formation is so you won't be able to gaze in this case to the left side and so because of that the actual preference or deviation will occur towards the contralateral side in this case the right side okay so again quickly recapping pprf you knock that out your conjugate gaze is affected you can't gaze properly to the same side if you can't gaze to that left side now what happens is your eyes start to deviate to the contralateral side next one move again medial here but again going anterior as we're working from back to anterior here we got this green structure called the medial meniscus if you knock out the medial elimination what does it do it takes sensory information what kind of sensory information fine discriminative touch proprioception vibration all that stuff takes it up from the body up to the central nervous system if you knock that out and in this case it's on the left side if you hit the left medial meniscus you're going to lose sensation such as fine discriminative touch proprioception vibration on what side the right side in this case okay so we the contralateral side so that's where you get contralateral loss of sensations move again anterior and you've got this big old red thing here called the corticospinal tracts that are running through the pawns you even have cortical bulbar tracks which control muscles of the head and the neck as well but either way you knock that thing out it hasn't crossed yet right so if it's on the left side that you're knocking out that corticospinal tract it hasn't crossed yet at the pyramids but eventually it will it'll come down to the pyramids and cross and go to the other side so you're going to get contralateral hemiplegia of what the entire side of that body in this case if it's the left corticospinal tract you'll develop right-sided weakness of the face the upper extremity lower extremity trunk boom roasted we just hit the medial pons but what do i want you to remember what artery is primarily occluded it's the pair medium branches of the basilar artery there that we're knocking out come down to the next one what did i tell you comes off of the uh the basilar artery okay it was number four comes off of it and supplies the anterior inferior cerebellum and supplies the lateral pons that was the icah so look at this diagram here here we have the basilar which was supposed to be this territory right here kind of kind of like make it like that so it fits but that was our basil artery territory is that getting hit right now from those pair medium branches no what structures would be getting hit if you're over here ooh baby we hitting that icah we hitting that aika so the ica is going to involve more of that lateral pons which we told you when we talked about that above and it's also going to hit the anterior inferior cerebellum so let's talk about what it does though if the ica is affected you don't get blood supply to the structures in the lateral pons so let's know what's in the lateral pons and if we damage that what would happen let's work our way out from the most lateral part of the pons and let's kind of work our way laterally medially and anteriorly okay so we're going to work from here and we're going to go this way so first thing here is you got these structures here most laterally in maroon called the middle cerebellar peduncles so those are a communication system they're a highway system between the pawns and the cerebellum allowing for a nice communication there between them now remember what it does is it takes sensory information from your spinal cerebellar pathways and takes that and puts that into the cerebellum so that the cerebellum can say hey i'm receiving all this proprioceptive information all of this kinesthetic information and i'm knowing where the position of the body is in three-dimensional space if you knock out that middle cerebellar peduncle on this case the left side all of that proprioceptive and kinesthetic information coming up via the spinal cerebellar pathways on the left side is going to get knocked out and you're going to not be able to coordinate where your position of your body is in a three-dimensional space and so this can lead to ipsilateral ataxia because you're hitting that middle cerebellar peduncle and everything from cerebellum is always ipsilateral okay so that's what happens there knock out the middle cerebellar peduncle ipsilateral ataxia because that's where the spinal cerebellar pathways are going into the pons move our way again we're going to go kind of medially and work our way anteriorly so we're going to hit this purple structure here this purple structure is your vestibular nuclei and a little bit of the cochlear nuclei so your vestibular nuclei are responsible for what a lot of your your equilibrium right so your dynamic equilibrium your static equilibrium and so what happens is if you affect these things you can lead to a loss of that equilibrium and that kind of presents sometimes as vertigo and vertigo also is not too great because what happens is whenever someone's really really dizzy and they have a lot of this abnormalities in their equilibrium it loves to stimulate what's called the chemo trigger zone and that chemo trigger zone will induce nausea and vomiting from that kind of like really significant vertigo so they can develop vertigo nausea vomiting also the vestibular cochlear system also does have a communication with what's called your vestibular ocular reflexes and so because of that they can also develop these beating of movements of the eyes called nystagmus if you hit the cochlear nuclei what does the cochlear nuclei do they're responsible for receiving information from that spinal organ of cordy right literally sound amplitude pitch all of that stuff for hearing for sound stimulus so if you lose that you can obviously develop deafness and sometimes a very high pitched sounds called tinnitus so we got ipsilateral ataxia we got definite vertigo nausea vomiting and nystagmus now we go to the green structure here the green structure here is called just descending sympathetic fibers those are coming from your hypothalamus remember hypothalamus has the descending sympathetic fibers that run down through the spinal cord if we knock these out you knock out the sympathetic fiber supply particularly to like the face and the eyelid and the eye the actual muscles of the eye particularly the the ciliaris muscles okay so what happens here so what happens is if you knock out the sympathetic tracks well is what's called horner's syndrome on that that same side so ipsy ladder so if you knock that left sympathetic tracks you develop left-sided horner's syndrome so what does that consist of well you knock out the muscles uh the tarsal plate muscles and so what happens is you can develop ptosis of the upper eyelid you can cause anhydrosis so again sympathetic supply supply sweat glands so you'll have anhidrosis of that side and sympathetic supply also goes to the pupillary muscles so normally your sympathetic wants to dilate the pupils but if you knock out the sympathetic system what happens they'll actually constrict and that's called meiosis of the pupils okay boom roasted move on okay now we go again we're going to move this way we'll come back to this little bugger a little bit later okay we're going to move on to this red one here the red one there is called your spine so this is actually part of your uh your trigeminal nuclear system so you remember your trigeminal nucleus you have the different parts in the midbrain the mesoncephalic part you have the central pontine part or principle pontine and then underneath that you have the spinal trigeminal nucleus we have that nucleus and then you have the tract when you knock out the nucleus particularly where the motor nuclei are the motor nuclei of the fifth nerve i'm sorry the fifth cranial nerve which is the trigeminal nerve you affect the muscles that they supply which is the mastication muscles and so if you knock out that left side you'll affect the muscles on the left side leading to decreased effectiveness of the mastication muscles on that left side the other thing is all of the sensations of the face come from the trigeminal nerve and that all gets taken into that trigeminal system so the trigeminal tracts also are going to get hit and so you're going to get ipsilateral loss of pain temperature some of the touch and proprioceptive sensations from the face that's where you get ipsilateral sensory loss ipsilateral weakness of the mastication muscles boom roasted what's the next let's go into this little blue dude the blue dude is actually going to be your spinal thalamic tracts so these are taking particularly pain temperature some of the crude touch pressure sensations not from the face but from the body so from your upper extremity your trunk and your lower extremities so for example if you knock out that spinal thalamic tract on the left side you're going to develop what remember what happens when you have sensations coming in via the spinal thermic tract they come into the spinal cord and they immediately cross at that level of the spinal cord usually maybe depending upon that maybe one to two levels detractable sore but again the whole point is it crosses the level of spinal cord and then ascends so if it's already crossed and we're at that point here at the the pons that means that if you knock out this structure the spinal thalamic tract the sensations are going to be on the right side so you'll develop contralateral loss of pain temperature maybe even some crude touch and pressure sensations okay so that's what you'll get there and then the last but not least is this dude here sitting in the middle is just their facial nerve nucleus so the facial nerve nucleus you actually know that it kind of wraps around the sixth nerve and then goes out right but if you hit the facial nerve okay what happens if you hit the left side it's ipsy lateral so you can develop ipsilateral facial weakness usually though it's the it's the lower kind of like third part of the face okay so it's the lower third part of the third part of the face okay but again you're going to develop ipsilateral facial weakness usually the lower part of the face that covers the lateral pons which again is supplied by what part aika medial pons the pair medium branches of the basilar alright let's finish off talking about again the other branches that we didn't really completely discuss we really talked about the medial ponds and lateral pawns but we didn't talk about the cerebellum because remember the basal artery does supply not just the pons but the superior anterior inferior part of the cerebellum through what vessels though well the superior cerebellar artery supplies the superior cerebellum that comes off kind of the top part of that basilar and then a little bit underneath that is going to be the ica that supplies the anterior inferior part of the cerebellum either way you occlude these vessels you damage those vessels you don't get blood supply to the cerebellum cerebellum is involved in so many things like posture tone coordination a lot of different things like that so if you knock that out you can develop things like ataxia so obviously kind of like loss of the coordination you can develop dysmetria so difficulty being able to kind of like track uh particular spaces like for when you're trying to move your finger to nose so finger to my nose to the to the actual clinician's finger they may overshoot it or they may undershoot it and they may have problems bringing it back to their nose as well this dido kinesis they have difficulty with kind of like those rapid alternating movements they might have like an irregularity in there and not be able to do it as quick and so things like that can kind of come up as well so again when we talk about basilar artery syndromes think about all of these things coming up but think about what vessel supplies the medial ponds paramedia branches of the basilar lateral pawns is ica and then for the cerebellum we're talking about superior cerebellar and ica i think we nailed that home let's move on to the last part which is the vertebral artery syndromes all right ninjas we are at the end i promise i know that this has been tough but let's stick through it together we got this ninja nurse we can do this so we're going to finish up with vertebral artery syndromes now vertebral arteries i want you to remember supplies the last part of the brain stem so we know pca hits the midbrain right we know the basilar hits our pawns superior cerebellum anterior inferior cerebellum vertebral is going to hit the medulla and the posterior inferior part of the cerebellum right so let's talk about that before we do that though let's briefly talk about the blood supply recapping it again so again what do we have these structures here coming up off of the subclavians your vertebrals that's number one right so vertebrals your right and left vertebral arteries what do we say that they need to remember what do these supply they give off their little branches and particularly they give off their branches through what's called the branch in the middle here you see this thing right here number two that's called the anterior spinal artery so it happens vertebrals come up as they come up and approach one another become the basilar they give off this little branch here called the anterior spinal artery so the anterior spinal artery is particularly the branch that supplies the medial medulla but we can still say the vertebrals also supply the medial medulla so when i say what gives you blood supply to medial medulla you should say your vertebrals and your anterior spinal artery okay good we got that we come up as we come up we recap this as we come up we fuse together make the masler what comes off the top of the basilar pcas what comes off underneath that superior cerebellar artery what comes off underneath that aika the last thing i need to talk about is as we come up before the vertebrals fuse and form the basilar not only do they give off anterior spinal artery but they give off this thing here what's that bad boy number three number three is your pica which is the posterior inferior cerebellar artery what does that supply what do we have left remember i told you vertebrals should give off a bunch of branches at the end of it though you should supply medulla you should supply what else the posterior inferior cerebellum well we got vertebral's getting the medial medulla we got anterior spinal hitting the medial medulla what's left lateral medulla pica and posterior inferior cerebellum pica so that's what i want you to remember vertebral's anterior spinal give you medium medulla pica gives you lateral medulla posterior inferior cerebellum boom roasted let's move on to that stuff then similar to the basilar we take a look at the medulla we take a cross section through the medulla we have here in organization posterior part of the medulla anterior part of the medulla when we look at this we see our vascular territories here in that cross section and blue as you see here through the midline is what the vertebral arteries and the anterior spinal artery that's supplying the structures in the medial strip of the medulla now we need to know what are the structures in the medial strip of the medulla if we damage them what are the clinical features we're so good ninja nerds aren't we we know this stuff boom smack dab here in the middle you have what's called the 12th cranial nerve the hypoglossal nerve the hypoglossal nerve is obviously responsible for tongue movement right so protrusion of the tongue moving it left moving it right moving it up moving it down curling it all that good stuff so if you knock out for example in this case the left twelfth nerve you won't be able to allow for there'll be weakness on that left side okay so there's going to be weakness on the left side of the tongue what will happen is is that the right half of the tongue from that normal right twelfth nerve will overpower and deviate the tongue to the weak side which in this case is our left side because the left twelfth nerve's injured so because of that you injure the left twelfth nerve the weakness on that left side right side overpowers and the tongue deviates to the same side as where the lesion is present which is the left side so you get ipsilateral deviation of the tongue all right so we got the 12th nerve nucleus the next thing is this green structure here in the middle and this may sound familiar to what we already talked about within the medial pons medial meniscus is responsible for what picking up fine touch proprioceptive discriminative touch vibrations all that stuff and bringing it up from one side of the body up through the brain stem into the other side of the brain if you knock out that left medial meniscus you're going to knock out sensations to the contralateral side of the body as long as it's after because medial meniscus comes after the nucleus gracilis the nucleus cuneis was just kind of the bottom part of the medulla so if you knock out that medial a meniscus you knock out contralateral proprioception fine touch discriminative touch and all of those things to the contralateral side so right side in this case so that's what you get here when you knock out that medial meniscus left corticospinal tract remember we're at the pyramids but we haven't gotten to the bottom and we as you go down the pyramids the decussation of the corticospinal tracts occur at the bottom of the pyramid so if we were at the decussation point then yeah we could potentially have ipsilateral weakness but we're at the point where we haven't decided yet within the medulla and so because of that you get no crossing yet eventually it will cross so you're going to get contralateral hemiplegia so if it's on the left side of the module that you're hitting you're going to develop right-sided weakness or right-sided hemiplegia okay or paralysis that covers the medial medulla which is supplied by what strip here vertebral and anterior spinal artery so again to recap it ipsilateral third twelfth nerve palsy medial meniscus so loss of contralateral sensations uh all the sensations we discussed and corticospinal tract contralateral hemiplegia so we talked about the medial medulla let's now talk about the lateral medulla so we know again medial medulla was supplied by the vertebral artery anterior spinal artery we can see that by that like territory that we colored here in blue now imagine if we kind of go out laterally do you see the vertebral arteries and anterior spinal arteries hitting that territory no that's within the realm of the pica right so if we knock out the pica we knock out the structures that are supplied within the lateral medulla so what are the structures in the lateral medulla and what happens if those things are damaged let's start here laterally work our way kind of like medially and then anteriorly because again this is the same section as compared here so this is still like the posterior portion this is the anterior portion that's lateral lateral medial so first thing here at the lateral part of this left part of the medulla here is going to be the inferior cerebellar peduncles it's the same thing that we talked about with pons it's just instead of it being middle it's inferior the spinal cerebellar pathways or any kind of proprioceptive pathways are coming up into the cerebellum and then it's going to be moving into the cerebellum from the medulla via these inferior cerebellar peduncles if you knock out that connection you knock out the ability to be coordinating our proprioceptive sensations which is involved in coordination so if you knock out that left inferior cerebellar peduncle you knock out the sensory proprioceptive information going to the left cerebellum and so that's going to lead to ipsilateral ataxia because again everything with a cerebellum produces ipsilateral symptoms and compared to the cortex which is contralateral so again knock out the inferior cerebral peduncle you knock out the communication of proprioceptive sensation to the left cerebellum you need the ipsilateral ataxia move immediately to this blue structure here called the nucleus ambiguous this is the big big big big big one that i want you guys to remember a lot of this stuff is pretty much the same what we talked about with lateral pontine pontine involvement it's the same this is the really big difference here when you talk about lateral medulla involvement as you're involving the nucleus ambiguous the nucleus ambiguous is the nucleus that gives way to particular nerves motor nerves for cranial nerves nine glossopharyngeal granule nurse 10 vagus and a teensy little bit of this accessory nerve cranial nerve 11. these go and supply particular muscles involved in speech and swallowing okay and so what are some of those muscles it's muscles of the soft palate muscles of the uvula muscles of the pharynx muscles of the larynx all of those things are involved and particularly stimulated by the nerves coming from the nucleus ambiguous if you develop a lesion in the pica and you knock out that nucleus ambiguous you knock out motor supply to all of the larynx pharynx softbowl and uvula and this can produce what's called a bulbar palsy ipsilaterals you're affecting the same side so what can that look like one thing is you affect the ability to swallow because you're hitting those pharynx muscles that can cause dysphagia you're affecting the speech production because you're hitting the larynx muscles that's causing dysphonia you're affecting your reflexes you know whenever you take like a tongue depressor and tap on someone's pharynx or tonsillar walls it triggers a gag reflex or if you take an endotracheal tube and you go down and deeply suction or aspirate things from their corine or trachea that causes a cough reflex which is elicited by your vagus nerve if you damage that you then have a decrease or absent cough gag reflex and the last thing is again remember that cranial nerve 10 supplies the uvula there's two halves of the uvula supplied by cranial nerve 10. if you so if there's actually a decreased supply or injury to in this case the left vagus nerve that left side of the uvula isn't going to be able to contract and so what happens is it starts to deviate to the opposite side because the other side is working properly and yanking it to the other side and so you do have a kind of what's called a contralateral uvular deviation so big things to remember this is the huge huge huge one to remember when there's lateral medulla involvement because of the pike lesion you know another name for the lateral medulla kind of lesion is or syndrome we call it wallenberg syndrome so remember that sometimes that can show up on your board exams all right so we got inferior cerebral peduncle we got nucleus ambiguous with the bulbar palsies the next one that we have here is this purple one called the vestibular nuclei now vestibular nuclei are involved with static equilibrium dynamic equilibrium and so what happens is they they help to be involved in a couple things one in maintaining balance the other one is they help to allow for the proper movement of our eyes whenever we're like shifting our head from side to side or up and down and whenever there is involvement of a lot of issues with the vestibular nuclei that can communicate with what's called our chemo trigger zone which is involved in nausea and vomiting if you injure the vestibular nuclei you then alter your ability to maintain static and dynamic equilibrium which leads to vertigo you alter the the connection to the chemo trigger zone and now there's more stimulation of it that it causes nausea and vomiting and you alter the vestibulo ocular reflex which is causing nystagmus now move out a little bit here to this green structure called the sympathetic tracts the descending sympathetic fibers that come from the hypothalamus you hit those you cause ipsilateral horner syndrome which we already talked about with the pons which leads to decreased sweating anhydrosis you cause ptosis of that upper eyelid and then you cause the pupil to not be able to dilate instead it constricts which is called meiosis next thing is this blue structure here called the trigeminal nucleus now the trigeminal nucleus in the pons there was the central pontine nucleus but there was the motor component of it as well that controlled mastication muscles and this part here in the medulla of the lateral medulla it's called the spinal trigeminal nucleus but there's no motor component of that trigeminal nerve there it's just sensory involvement there and the tract the the spinal thalamic sorry the trigeminal tract is also there as well so the spinal trigeminal nucleus and the associated tract there only picking up sensory information like pain temperature touch proprioception from that same side of the face you whack that left spinal trigeminal nucleus and tract you lose sensations such as pain temperature touch proprioception from that left side of the face thus ipsilateral loss of sensations of the face last thing here is that spinal thalamic tract spinal thalamic tracts you have the anterior and lateral they carry crude touch temperature pressure right if you knock this thing out on that left side remember spinal thermic tracts cross at the level of the spinal cord whenever they're coming into the spinal cord so if you knock that out you're going to be affecting sensations on the contralateral side so for example you knock out that left spinal thalamic tract here in the lateral medulla you cause loss of sensations on the right side contralateral side which is going to be in this case pain temperature crew touch and pressure and that would cover all of the things that could become present when there's lateral medullary involvement wallenberg syndrome due to what kind of vessel damage the pica okay whereas if it's medial medulla that's going to be vertebral artery and more particularly the anterior spinal artery let's move on to the last part so we know that the vertebrals again we already kind of concluded this at the beginning they supply medulla and they supply posterior inferior aspect of the cerebellum so let's quickly recap that blood supply to the cerebellum so again we have vertebral artery here so we'll kind of mark this here as a vertebra we only see one half of it in the sagittal view here's your vertebral artery gives off this branch here called the pica pico supplies the posterior inferior aspect of the cerebellum then you come up here to this part here called the basilar artery and the basilar artery will give off respectively the ica supplying the anterior inferior cerebellum and then it'll give off the superior cerebellar artery which will apply the superior cerebellum the one that we have to focus on with respect to the vertebral arteries is you knocking out the pica if you knock out the pica you affect the blood supply to the posterior inferior aspect of the cerebellum if there is a involvement of the cerebellum this is important because it leads to alter abnormalities within coordination posture balance things of that nature which can present as ataxia if you injure the right cerebellum you cause a taxi on the right side if you injure the left cerebellum you cause a taxi on the left side so how will this present in this case they can have ipsilateral ataxia and this can also present with what's called dysmetria whenever they're trying to do the finger to nose test we already talked about that or this diatokinesis with rapid alternating movements and this would cover vertebral artery stroke syndromes as well as all of the stroke syndromes ninja nerds you guys got through it all right ninja nerds in this monster of a video we talk about stroke syndromes i really hope that it helps i truly hope that it makes sense and if you guys did enjoy it continue to support us ninja nerds we love you we thank you and as always until next time [Music] you