Cranial Nerves Exam | Clinical Skills

what's up ninja nerds in this video today we're going to be talking about how to perform a cranial nerve exam before we get started make sure you guys go down in the description box we have links to our patreon on our patreon we'll have comprehensive notes on the physical exam that we're going to be doing on cue today going through all the cranial nerves in a sequential order so go check that out also if you guys like this video and benefit from it please hit that like button comment down in the comment section and please most importantly subscribe so let's go ahead and get into it so cute today i'm going to be performing a cranial nerve exam on you is that okay yeah it's great all right so what i'm going to do now is i'm just going to go over wash my hands make sure that we're being clean and so when we're doing a cranial nerve exam we're going to start it's first important to remember that we have total of 12 cranial nerves we're going to start from cranial nerve one and work our way down to cranial nerve 12. the first cranial nerve that we're going to evaluate is the olfactory nerve the function of the olfactory nerve is primarily for smell or olfaction so we need to know how do we evaluate that here on cue so the first thing i need to do is make sure that q's nasal passages are patent that there's no obstruction that could alter the reliability of my test so what i'm going to have you do is plug your right nose here for me and i'm going to take a breath in through your nose and out through your nose good and i'm going to do the same thing for the other one good and i hear complete patency of that nasal airway so i know that there's not going to be anything that's altering my actual test now that i know that what i'm going to have q do is i'm going to have you close your eyes and again cover include your right nostril and what i'm going to do is i'm going to present a particular smell to him and i want him to be able to identify what that particular smell is so cute can you tell me what you smell here it smells like coffee perfect so that is perfect intactness of that olfactory nerve we're going to do the other side keep your eyes closed and again q i'm going to present a smell to you can you tell me what you smell that's cinnamon perfect so the olfactory nerve is intact beautiful now here's something that we got to be thinking about if the olfactory nerve wasn't working properly and they weren't able to identify those smells that could be indicative of something called anosmia now a nozomi can have various causes it could be acquired and think about it if there was an infection of the nasal mucosa like in a rhino sinusitis like covid19 or there was damage to those nerves like in parkinson's disease or compression of that nerve like in a tumor like a meningioma or damage to the nerve from like a fracture of the ethmoid bone those could be potential causes of anosmia but it also could be congenital where you don't form that olfactory nerve in something called coleman syndrome now the olfactory nerve we don't commonly test this unless q came in today complaining of some decreased or loss of smell that covers cranial nerve one let's now move on to the second cranial nerve also known as the optic nerve the optic nerve is primarily responsible for vision and we can test this in many different ways the first way we're going to test this is by the visual acuity test using our good old snellen charts let's go ahead and do that all right so we're going to be assessing visual acuity on cue the best way to do that is just your good old snell and chart and on the bottom will tell you the distance that you generally want to be away from the patient to examine that it's about six feet so what i'm going to do is i'm going to go ahead and have q read some letters off for me so q what i want you to do is cover your right eye and q can you read these letters here all the way at the bottom from left to right yep e c t p n l beautiful so his left eye os 2020 good stuff we're going to cover the other eye so now we're going to be testing his right eye same thing cue at the bottom here can you read the letters from left to right e c t p n l beautiful so his right eye o d 2020 now we're going to test both eyes can you read the last line left to right here e c t p n l good so both eyes o u 2020 visual acuity is on point let's now move on to the next test which is going to be visual fields all right so we've tested q's visual acuity his was perfect 20 20 right eye left eye both eyes now if he did have those higher numbers it wasn't 20 20 maybe 20 70 2100 and one or both eyes then i'm thinking that there's something going on and there could be various reasons for this there could be some retinopathy maybe diabetic retinopathy hypertensive retinopathy if he was older which he's not i might be thinking about macular degeneration or maybe just a general astigmatism of some kind so that's what i would be thinking about if there was something going on with his visual acuity now if we're going to assess visual fields that's the next thing that we're going to test on him the best way to do that is by doing a finger counting method there's many different ways we're going to use the finger counting method on him so key what i'm going to have you do is kind of turn your kind of like uh yeah perfectly straight line with me and now what i'm going to do is i'm going to have you cover your right eye what i want to do is i want to test q's peripheral field and his central visual field so he's covering his right eye i'm going to close my left eye to keep my visual fields similar to his and i'm going to have my arms about equally distant between me and him and i'm going to come up so i'm in kind of like a superior quadrant of his central peripheral fields and q what i'm going to do is i'm going to put some numbers up i want you to tell me what numbers you see okay yeah two good two good and i'm gonna come down to my inferior quadrants same thing q tell me how many fingers i'm pointing one good two good and so by doing that i'm testing the visual fields peripheral on the left central on the left i'm going to do the same thing with the other eye so i'm going to have you cover your left eye he's covering his left eye so i want my visual fields to be the same as his so i'm going to close my right eye same thing i'm going to get my arms about equally distant away i'm going to come up into about the superior quadrants same thing q can you i want you to tell me how many fingers i'm pointing up two good two good i'm going to come down to the inferior quadrants one two good and so both visual fields the peripheral and central on the right eye are beautifully intact and there's no field cuts what would i be worried about if i was doing this and q lost his vision his peripheral visual fields on both eyes i've been thinking about something called bi-temporal hemianopia and that's a very very common when there's a pituitary tumor sitting on that optic chiasma because it affects the fibers that are crossing if there was something where let's say he couldn't see the visual fields on his left peripheral and his right central then i'm thinking that he's losing his field cuts there's field cuts on the left visual fields and that's called left homonymous hemianopia which means that there could be a right optic tract lesion or a right occipital lobe lesion so these are things to be thinking about when you're assessing someone's visual fields one more thing to remember is when you're assessing visual fields we were doing the counting finger kind of method there is other ways to do it you can do the wiggling finger method which is a kinetic target and so those are easier to identify than something like static like just your fingers okay like counting so i would highly suggest do the counting fingers method and if there was a field cut then do the wiggle finger method afterwards but in this case q's visual fields are full on confrontation so the next thing that we'll assess for q is we're going to go ahead and assess his pupillary reflexes all right so when we're going to be examining q's pupil responses the first thing that we need to do before we even go and shine a light in those beautiful green eyes is we need to take and look at his pupils and so i just want to kind of notice really quickly just looking at them in an ambient light are they pretty much symmetrical so i want to make sure that one side is not bigger than the other if they're dilated okay the next thing i want to make sure that they're not pinpoint and i want to make sure that they're nice and round so by looking at them they look nice and equal they look round now i need to determine if they're reactive to light so this is where we test the pupil reflex it's important to know the pathway of the pupil reflex you shine a light into his eye it hits the optic nerve the optic nerve will send that information to your brainstem particularly the midbrain activating the third cranial nerve the third cranial nerve would then send out supply to his actual uh his muscles of the uh around the pupil and caused them to constrict so i should be able to examine a direct response and then a consensual response let me show you what that looks like so if i took a light here i'm shining it into his right eye as we come here i'm going to bring the light in look at that constriction right there when from me shining light into this eye that's called the direct response i'm going to shine the light into the right eye but look at his left eye it should constrict that is called the consensual response i'm going to do the same thing on the other eye because i want to notice that they're both it's reactive similarly on both eyes so i'll come over here shine the light into his left eye look for that direct response nice constriction and then again focus on his right eye and look for that nice constriction of the right eye that's the consensual response so that's going to tell me my pupil reflex now it's important to remember if there was an issue where the pupils didn't respond the way you wanted them to they didn't react in other words they didn't constrict or there was an unequal restrict a constriction you got to think about the prob the parts in that pathway is there something wrong with the optic nerve is there something wrong with the midbrain or is there something wrong with my oculomotor nerve the easy one to kind of just test really quickly while you already have your light here is what's called a relative afferent pupillary defect or an rapd this is testing to see if there's something wrong with his optic nerve sensing the light so what i would do is as i would shine a light and let's say he has a right optic nerve lesion so he's not going to be able to pick up the sensations as well when i shine that light into his right eye that's going to lead to decreased signals going to his midbrain decreased signals going through the oculomotor nerve and it's not going to be causing constriction of those pupils now if they don't constrict they may dilate a little bit and that's called a relative apd also sometimes referred to as a marcus gun pupil so if i were to do the swinging light test to look for a relative apd i'm just going to focus on one eye at a time i would shine a light look at the constriction in that pupil note it very very interestingly then come to the other one shine the light into that and what i'm looking for is i'm looking for that constriction to be the same amplitude in both eyes and i'm looking for them to constrict and not dilate okay if i shine the light into that right eye that was damaged what would happen then he would dilate both eyes would dilate because there's an issue with his optic nerve the afferent pathway if there was problems with the midbrain there could be a stroke if there's problem with the third nerve maybe there's a herniation that's compressing it or a communicating artery aneurysm the posterior cerebral communicating artery that's compressing it as well the last thing that i could test is after i've done the pupillary and the swinging light test is i could do what's called a blink to threat test this also tests the second cranial nerve as well as another nerve called the facial nerve so what i would do to test the blink to threat is i would take my hands i would have them look straightforward and i would come like i'm going to hit him i obviously wouldn't but i get close enough that it would trigger his optic nerve to sense that send that to his brain stem activate the facial nerve come out and the facial nerve will cause the orbicularis oculi to contract so do the same thing on that one and on that one and he has a blink to threat on both sides so it means that that is intact with respect to his optic and his facial after we have completed the pupils looking at it through the pupil reflex the swinging light and the blink to threat now what we can do is is we can do a fundoscopic exam all right so now what we're going to do is we're going to do what's called fundoscopy we're going to take a look at a bunch of different stuff in cues eye and so we're going to be looking at the retina we're going to be looking at the optic disc we're going to be looking at some of the blood vessels in that area and we're also going to be looking for something really really quick called a red reflex so what we're going to do is i'm going to take here my ophthalmoscope i'm going to kind of brace my hand over here on q's head and then i'm going to take my light here and i'm just going to kind of look through it to see if i find the red reflex and then once i find that i'm going to follow it in and take a look at his retina and what i'm noting here is i'm noting his optic disc i'm looking to see if it's pale if it's cupped if it's blurred margins around it i'm looking at the retina to see if there's any what's called jerusalem or microhemorrhages or cotton wool spots i'm looking at the blood vessels as well to see if there's any av nicking or if there is any copper wiring and just seeing if there's any signs of retinopathy there and then if i can i'll look a little bit towards the macula and see if i see any lesions there as well after i've done that on the right eye i'm going to do the same thing except i'm just going to come over here on this side again brace my hand here have my light kind of zooming in there and with my left eye find his red reflex and follow it all the way in noting all the things that we just talked about in his right eye after we've performed the fundoscopic exam and that would pretty much conclude our cranial nerve two things that i could be looking for that would be abnormal if you really get a good look at it is sometimes if the optic disc is really blurred and the margins are a little hard to see it could be indicative of what's called papilla edema which could be indicative of high intracranial pressure if the vessels look a little odd there's av nicking there's copper wiring that could be indicative of maybe some retinopathy same thing hypertensive or diabetic and again looking for any macular degeneration or any micro hemorrhages in the retina as well after we've performed the second cranial nerve exam we've pretty much finished everything in that we're going to move on to three cranial nerves in tandem the third cranial nerve which is known as the oculomotor the fourth which is known as the trochlear and the six which is known as the abducens nerve these are really really good at moving our muscles of the eye what's called the extra ocular muscles and there are so many of them easiest way that i find you guys to remember them is lr6 lateral rectus is supplied by the sixth cranial nerve abducens the superior oblique so4 is supplied by the trochlear nerve and all the rest of them superrectus inferior rectus inferior oblique medial rectus and even the levator palpable superioris is supplied by the third cranial nerve so when we're noting extraocular movements what i like to do before i even have him follow my finger and fixate and track is i just want him to kind of look at me you can have you kind of look straight at my nose here and i'm looking at his gaze this is very very important to note because i want to know if his gaze is midline meaning that all the muscles are working kind of nicely that not one's pulling or not one's weak and it's deviating anywhere i want to make sure that they're midline and that there's no disc conjugate gaze not one wonky eyes looking out this way or looking in a different direction than it should be after i've noted that his gaze is midline then i'm going to assess his ability to fixate on my finger so cue what i want you to do is just look at my finger and i want you to only follow my finger with your eyes not your head okay and what i'm going to do is i'm going to make an h so i'm going to move this way towards the right as i move to the right think about what muscles i'm activating i'm activating the right lateral rectus and the left medial rectus i'm going up i'm testing his superior rectus in the inferior oblique coming down testing the inferior rectus and the superior oblique going back over this way testing his left lateral rectus right medial rectus coming up testing his superior rectus inferior oblique coming down testing his inferior rectus and superior oblique and again we can come back to midline all of those movements were beautiful there was no weakness or paresis towards one side he didn't have a preference they were moving nice and smooth other things that you'd want to ask is while he was doing that did you develop any double vision at all cue while i was moving my fingers around no so that's good as well the other thing that you want to look for is if you really can sometimes see it sometimes if you move your uh your finger in one direction it can trigger like a little beating of the eyes called a nystagmus and sometimes that's something that you'd want to further evaluate as well but in q's case extraocular movements were intact they were full nice pursuit smooth movements the next thing i would do is i would test something called saccodes and these are your nice reflexive eye movements these kind of are coordinated by your frontal eye fields and your frontal lobe and your pair medium pontine reticular formation in your brain stem and so what i like to do with this is i'm going to test his volitional saccades so q can you go ahead and look to the right and look back at me look to the left look back at me look up look back at me and i'm going to have you go ahead and look down and look back to me all those movements were really really quick they weren't slow there wasn't any nystagmus and they were nice and smooth so the sakad's this cicada eye movement was perfect and it's moving perfectly well the last thing that i would do for his extraocular move well his third fourth and sixth cranial nerves is i would look at his eyelids particularly the upper eyelids there's a muscle called the levator palpable superioris which helps to pull the eyelids up sometimes if there's injury to the third cranial nerve or is the sympathetic plexus that can droop and that can cause something called ptosis so i just want to take a look at his eyelids can you look straight at me cue and i don't notice any drooping of one eyelid or the other so that's perfect no ptosis is present so that's how we would test our third fourth and sixth cranial nerve the next cranial nerve that we would go and test is the trigeminal nerve which is the fifth cranial nerve the fifth cranial nerve is responsible for a couple different functions one is sensations of the face so how would i test sensations of the face well there's two types of sensations that i want to test one is light touch and the other one is more of like a pen prick type of sensation so what i'm going to do is i'm going to go over here and get my cotton swab and i'm going to get the a broken end of my cotton tip applicator and we're going to go ahead and test q's ability to identify light touch of the face so q what i want you to do is close your eyes and what we're going to do is we're going to test this top division here so key whenever you i want you to tell me if you feel this okay can you feel that cue yes good can you feel this yes good did they feel the same on both sides yes good so his first division v1 the ophthalmic division he picks up light touch sensations equally on both sides now i'm going to come down to the middle can you feel this cue yes can you feel this yes does it feel the same good and then that's the v2 division or the maxillary and i'll come down to the mandibular v3 can you feel this cue yes and can you feel this yes does it feel the same good and so that tells me that the light touch sensation of the trigeminal nerve is intact now we'll do is we'll test like a pin prick kind of a little bit more of a an intense stimulus like a pain stimulus and what i'm going to do is i'm going to take the end of a cotton tip applicator break it off and i have a nice little pointy end we'll be nice and gentle to cue here we won't be too mean so human have you close your eyes again and we're going to do the same thing can you feel this cue yes can you feel this yes does it feel the same can you feel this can you feel this yes does it feel the same yep and can you feel this yep can you feel this yep and does it feel the same yep another thing that we could do if we really want to determine if he could discriminate the differences is i could go back and forth and i could say can you tell me what this feels like is it a soft or cotton swab sensation or is it the pinprick sensation we're going to defer that at this point but that's the way that you could go about kind of determining the discrimination in this aspect but in this case right here v1 v2 v3 sensations of the trigeminal nerve are beautifully intact the next thing that we would do is we would test the motor function okay which he that the trigeminal controls the mastication muscles the muscles that are involved with chewing three primary muscles that we'll examine the first one that we'll examine is the temporalis muscles the second one is our masseter muscle and then the other one's really deep called the pterygoids so the first thing that we'll do is is i'm just going to go ahead and take a look at cue and i'm going to notice any asymmetry if maybe one muscle is a little bit more hypertrophy and thicker than the other and i don't notice anything obvious on this kind of examination then what i'll do is i'll have him clench his jaw okay when he clinches he's going to activate two muscles temporalis and the masseter i just want to go ahead and palpate and see if i feel those muscles kind of like contracting and the same thing oh yeah these are he's got a jaw of steel so when you're feeling those you're feeling for the tone and the other thing you could ask is did it feel tender when i palpated around that area there no good so that means that the trigeminal nerve which is supplying the masseter and the temporalis is working well next thing we'll do is the pterygoid so with the pterygoids i'm gonna have you open up your mouth and don't let me push it close and that's nice and strong good strength against the resistance and so the pterygoids are working well too the next thing that we could do is there's the reflexes so we could test reflexes and one of the really really big ones to test especially in a a comatose patient or an altered patient is what's called the corneal reflex this is one of the first reflexes or first types of things on the trigeminal nerve if it's damaged to go and so the corneal reflex it's important to know the sensory afferent efferent pathway afferent is going to be the trigeminal nerve it supplies the cornea goes into the brain stem and activates what nerve in this case it would activate the facial nerve which would come and cause the orbicularis oculi to contract so what i would do is i would have cue i'd have you kind of look like straight here and what i would do is i would just come here and tap over that cornea area and it should trigger a blink sorry cue i'm going to do this one more time and again triggers that blink type of effect so that would tell me that the corner reflex is beautifully intact there's nothing going on with the facial afferent nothing i'm sorry nothing going on with the trigeminal via the afferent and nothing going on with the facial efferent pathway the last thing i could test if you really want to go the extra mile as a ninja nerd is you could test what's called the jaw jerk reflex this could be in something that is really important in what's called an upper motor neuron lesion upper motor neural lesions usually produce what's called hyperactive reflexes and so what i could do is i could have cue could you open up your jaw a little bit here for me i'm going to go ahead and place my finger over kind of the chin mental region here and i'm just going to go ahead and tap my finger with my reflex hammer and what i'm looking for is if someone had an upper motor neuron lesion their jaw jerk reflex would be very pronounced very hyperactive and so that's something that you'd want to look for and think about if they have some type of upper motor neuron lesion that you're investigating or you're aware of so that's how we would assess the trigeminal nerve so we've so far we've covered one two three four five and six the next one that we're going to cover is the facial nerve or cranial nerve seven this one is primarily having a motor function particularly for the muscles of facial expression so how do we test this the first thing it's really easy you actually just would tell cue you'd look at him first before you have him do anything just take a look at his face look for any asymmetry at rest do i see that maybe one eyelid is pulled like his forehead is a little bit less wrinkled on one side do i see a flattening of his nasolabial fold on one side things like that in this case his face is symmetrical just at rest now what i'm going to do is i'm going to trigger some movements so cue can you go ahead and raise your eyebrows and look to see if it's symmetrical on both sides which it is okay next thing i do is i have him close his eyes really tight and don't let me open them beautiful beautiful so him closing those eyes and keeping them close is a good sign as well next thing i would do is i would have him smile showing teeth okay look at that smile so what we're noticing is that it's symmetrical it's not kind of drooping not pulling more on one side and i'm looking at those nasolabial folds to see if there's any flattening of one side as well the last thing that i would test is i would have q puff out his cheeks and i would try to push on those and see if they collapse really easily or if he couldn't actually puff his cheeks out at all and again all the motor functions which are controlled by the facial nerve in cues situation are completely intact normal strength in all of those situations there's one more function particularly that you could examine for the facial nerve and that is taste in this case we're going to defer it but the facial nerve it has taste sensation it picks up taste within the anterior two-thirds of the tongue you should remember your tastes is sweet sour salty bitter and technically even umami so what i would do is if i were to explain how i would do this i would have cue close his eyes stick his tongue out i would take a particular taste and place it on the anterior two-third of the tongue and say q what did that taste like and he would say it tasted like sweet sour salty or bitter if there was any loss of sensation there that would make me think that there may be potentially something wrong with the facial nerve alright so before we move on to the next cranial nerve it's important to remember one last thing remember that if there is an issue where the muscles of facial expression which are controlled by the facial nerve are altered in such a way it's important to perform those functions evaluating him raising his eyebrows closing his eyes smiling and puffing out his cheeks because it can help us to differentiate an upper motor in our lesion like a stroke versus a lower motor neuron lesion something like bell's palsy okay so that covers our facial nerve the next thing that we're going to do is move on to the next cranial nerve which is called the vestibulocochlear nerve or also the cranial nerve eight now there's two portions that we're going to test the cochlear portion which is for hearing and the vestibular portion which is more for your balance and coordination aspects so when we test the cochlear portion we're just testing hearing and the best way to do this is testing what's called auditory acuity so what i'll have you do is i'll have you occlude your right ear cover your right ear and i'm going to kind of just rub my fingers together and present it next to his left ear and ask him if he can hear it can you hear that cue yes and what i'm going to do is i'm going to move far away until then tell me when you can't hear the sound can't hear it good so he could hear it right next to his ear and he could hear at a pretty decent distance away so that means that that left ear is hearing everything properly there's no signs of deafness or decreased auditory acuity on that side we're gonna do the same thing cover the left ear and again can you hear this cue yes tell me when you can't can't hear good so again same thing could hear it right next to the ear and can hear a pretty decent distance away so again that right ear is also picking up everything auditory acuity is attacked on that side now let's pretend for a second and that q is saying hey either came and complaining i'm having some problem hearing out of this right ear or when i do this test maybe he can't even hear my fingers right next to his right ear that would lead me to do another test to evaluate what's going on with this is there some type of deafness like a conductive deafness or a sensory neural deafness and that's when we would do something called the weber and renee test so the first test we're going to do is we're going to do what's called the weber test so i'm going to use my tuning fork and what i'm gonna do is i'm gonna give a nice little bang to it and i'm gonna place this on his forehead and i'm gonna and i'm gonna ask you hey q can you hear this equally on both sides or do you hear it more on one side than the other it's equal equal so there's no lateralization of the sound and that's good because generally if someone has conductive deafness it'll lateralize to the ear that they're having problems hearing out of and if it's sensory neural deafness it'll lateralize to the good ear the one that they're not having any issues with so since you could hear it equally on both sides i could stop right there but if we're going to be a little bit more thorough the next thing we could do is let's say that he lateralized he heard it a little bit more louder on the right side then i would do something called the renee test i'll do the same thing give a nice little bang to my tuning fork and what i'm going to do is i'm going to place this on his mastoid process and i'm going to ask him cue can you hear this yes tell me when you can't hear it i can't hear it so then what i would do is i would bring this next to his ear and ask him can you hear this still cue yes good and so since he could hear the actual sounds when i put it on his mastoid and next to his ear canal that's a that means that air conduction is greater than bone conduction which means that it's most likely normal but there could be signs of sensorineural deafness you would just have to do further testing like audiometry testing so again big thing to do with these is auditory acuity if there is an issue you can follow it up with a weber to look for lateralization and then renee to determine if the air conduction is greater than the bone conduction which would be normal but also could be indicative of a sensory nerve deafness or if i did the same test where i put it behind his mastoid process he says he could hear it then i move it next to his ear and he can't hear it that means that the bone conduction is greater than the air conduction and that could be indicative of something like a conductive deafness so now what we're going to do is we're going to test the vestibular portion of the vestibular cochlear nerve and this involves a test called the past pointing test and so what i'm going to have q do is i'm going to have him kind of extend his arms outwards two fingers and i'm going to put my two fingers kind of just underneath it and then q what i want you to do is raise them above your head and bring them back down and touch my fingers okay now what i'm going to do is i'm going to close his eyes and do it two times go ahead and what i'm noting is if he's able to do this and come back and touch my fingers and the fact that he is able to do that tells me that the vestibular portion of his vestibular cochlear nerve is intact he's able to have that proprioceptive sensation and his tracks are activating properly to bring him back to where my fingers were so that's a good sign the vestibular portion of the vestibulocochlear nerve is beautifully intact if there was some issues there you'd start thinking about maybe an inner ear disorder or maybe some type of brain stem dysfunction but in his case it's good so we've concluded vestibular cochlear now we're at the point of the glossopharyngeal nerve which we're going to combine because they work in tandem with the vagus nerve so glossopharyngeal nerve is the eighth cranial nerve i'm sorry ninth cranial nerve and the vagus nerve is the tenth cranial nerve they work in tandem except for one little exception the glossopharyngeal nerve also is responsible for taste right but where remember the facial was for the what anterior two-thirds and then the glossopharyngeal is going to be for the posterior one-third of the tongue and again i would be doing what same thing i said before i'd have him close his eyes stick his tongue out and i would present taste tense on that post here one third of the tongue have him identify that the inability to identify that could be made so there might be something wrong with the glossopharyngeal nerve but more specifically we're going to test the glossopharyngeal nerve and the vagus nerve in tandem the best way to do that is doing what's called the gag reflex and so what i'm going to do is i'm going to get a cotton tip applicator you can also use like a tongue depressor if you wanted to do that and we're going to go ahead and tap the posterior pharynx or near the tonsillar pillars to trigger a reflex so it's important before we do that to know the pathway sensory since the sensations from the soft palate the uvula the tonsillar pillars and the pharynx are carried by the glossopharyngeal nerves when i tap it it'll activate that go to the brainstem activate the vagus nerve which controls the muscles of the soft palate the uvula and the pharynx in some of the muscles around the tonsillar pillars triggering a contraction of those muscles if i tap it and he gags that means that the reflex is intact those nerves and the brainstem is intact so let's go ahead and test that reflex so i have my cotton tip applicator here what i will do is i'll have q open up your mouth really quick i'll be nice and gentle and i'll come back and i'll go ahead and tap sorry buddy tap that area and we were able to trigger kind of a gag reflex i won't do it again i don't want to be mean but i could try to do that near the tonsil pillars on both sides or the pharynx but either way his gag reflex is intact now here's something to remember if someone has a negative gag reflex does that mean that there is a lesion it could but it also may not be something that you have to worry about gag reflexes should be something that if they had it previously and they lost their gag reflex that would be something that you want to be concerned with but generally someone could have a negative gag reflex and everything be totally fine the next thing that we want to do is we've tested sensation of glossopharyngeal we've tested some of the functions of the vagus what else do we have to do well the vagus nerve is responsible for not only just the triggering the gag response but also it helps to move that soft palate that uvula and it also is involved with swallowing and speech so we've got to test all of those so how do we do that well the first thing i want to do is i want to take a look at q's mouth and get a look at what all of those things look like at rest all right so now the next thing that we want to do is we want to again evaluate the glossopharyngeal nerve and the vagus nerve kind of in tandem and so before i even have q say ah and look at that soft palate and uvula to see if they're deviating or if they're moving symmetrically i just want to take a look at his mouth in general at rest so what i'll have to do is open up his mouth really nice and i'm just going to take a look look at that uvula see if it's deviated and look at the soft palate and see if it's also kind of one size maybe more lifted than the other and in q's case the uv is nice and midline that soft palate is again not one side is deviated more than the other it's perfectly kind of inline and symmetrical so that's good and the reason why i want to look at that is because sometimes if someone has a vagus nerve lesion what happens is that uvula can deviate and it can actually kind of deviate uh towards like uh one side and that may be telling you that there may be a vagal nerve lesion as well so it's good to be looking at that as well at rest now what i'll do is is i'll have him again open up his mouth and i'll have him say ah good and i looked at that soft palate to see if it was elevating symmetrically and again to notice if the uvula deviated to one side or the other okay so so far we've tested the taste of glossopharyngeal we've tested the gag reflex we've also looked at that soft palate that uvula making sure it's symmetrical no deviation that you could see in a potential vagal nerve lesion the next thing that we want to do is again the vagus nerve we obviously know it controls the movements of the soft palate the uvula but it also controls the contraction of some of the muscles that are involved in swallowing or deglutition now you can just ask the patient to swallow but let's be a little bit more dramatic and we can ask the patient to sip some water to take a drink of water and then go ahead and swallow and again we're just examining that making sure that there's no difficulty in that process in which cues case no issues and so there is no signs of dysphagia in that case meaning that the vagus nerve is being well propagated there's normal action potentials down it controlling all the degluting process all the muscles that are involved in swallowing so in his case no dysphagia the other thing is that the vagus nerve not only controls the muscles of the pharynx and some of the muscles that are involved in swallowing but it also involves the muscles of the larynx that involved in speech and so one of the particular nerves is the recurrent laryngeal nerve and so what we can do is we can just ask the patient to communicate with us ask them a question q what brings you in today i'm here for my annual physical exam good and so just by listening to that communication between me and q i didn't notice any hoarseness in his voice i don't notice any strider and good communication no aphonia or dysphonia so the speech in this case is well intact the other thing that i could go and do is i could test a cough reflex the cough reflex is basically activating the sensory fibers of the vagus nerve going to the brain stem coming out via the efferent fibers of the vagus nerve in his case he's able to communicate he's able to swallow i don't really need to do that but if i did ask him to cough and he wasn't able to cough or he had a non-explosive cough that may make me think about something going on with that vagus nerve now this is a really important test and someone who is comatose or intubated where you would want to do a cough reflex and you would generally take a suction and push that down the endotracheal tube to trigger some irritation there and a cough reflex that's very very important in comatose or intubated patients but in this case we're just going to defer that in saying that his communication his all the other functions of his vagus nerve were beautifully intact so that covers our glossopharyngeal and our vagus kind of in tandem now let's move on to the next one which is the accessory nerve the accessory nerve is the 11th cranial nerve and it's primarily going to be a motor nerve and there's two muscles that you guys want to remember the first one is the sternocleidomastoid muscles and then the other one is going to be the trapezius muscle and what we've got to do is test the strength of these muscles against resistance and so what i'll do is i'll test the right style test his sternocleidomastoid particularly we'll test his left one so i'm going to have him look to the right and what i'm going to do is i'm going to take my hand i'm going to have my hand kind of palpating this muscle here and i'm going to ask him to resist me pushing his head in the opposite direction this way which he is this muscle is contracting really nice and i could also palpate here and ask him did you have any tenderness when i palpated over that area and i do the same thing now we're going to test the right one so i'd have them too to the left here again i take my hand here kind of brace it have my hand kind of on the sternocleido and have him resist that movement here and i palpate normal strength he's jacked and again no tenderness to palpation on that area there no good and so that sternocleidomastoids are working really really well next thing i could do is i could test the trapezius muscles and so what we do is just have him shrug his shoulders and when i shrug have him shrug those shoulders my job is to try to push him down and not let him push me down and he had good resistance normal strength against me trying to push down on those shoulders and so that tells me that the accessory nerves supplying these trapezius and a sternocleidomastoids are working well there's no weakness on those sides that covers the accessory nerve we're down to our last cranial nerve engineers which is the hypoglossal nerve the hypoglossal nerve cranial nerve 12 is responsible for movement of the tongue now before we even ask him to start sticking his tongue out at us and moving it all around we just want to get a look at the tongue because the reason why is in certain lesions of the hypoglossal nerve you want to determine if there's any atrophy or fasciculations because that may be more indicative of like a lower motor neuron lesion so what i'll do is i'll just have him kind of open his mouth and i'm just going to look at that tongue i'm going to look to see if there's any atrophy hypertrophy or any fasciculations in this case and i don't notice any so that's good the next thing we'll do is we'll test his ability to protrude his tongue out so can i have you stick your tongue out good and then i'll have you move it to the right move it to the left good and then you can go back in the mouth there what i would be looking for is if he stuck his tongue out and it kind of like deviated to one side that may make me think about a hypoglossal nerve lesion so what i would be thinking about let's say it deviated towards the left in that case i might be thinking that maybe there's like a left hypoglossal nerve lesion okay so in this case his tongue was midline he was able to move it left and right full movements there beautiful last thing that we would do with the hypoglossal nerve is i would have him go ahead and stick his tongue in the corner of his mouth here like he's going to push it against his cheek and i'm just going to push against it normal strength there same thing for the other side push against it normal strength there and that would conclude my examination of the 12th cranial nerve as well as all the cranial nerves in this physical exam video all right ninja nerds in this video today we talk about the cranial nerves i hope it made sense and i hope that you guys did enjoy it also down the description box please go check out our patreon there you guys will find all the notes that cover this physical exam in detail and you guys will be able to follow along with us as we go through to helping your learning process also big shout out to our man cue for being our patient today in this cranial nerve exam you guys want to check him out connect with him we'll have a link down in the description box to his twitch q dirty baby all right ninja nerds we love you we thank you and as always until next time [Music] you

Channel: Ninja Nerd

Views: 572,630

Keywords: Ninja Nerd Lectures, Ninja Nerd, Ninja Nerd Science, education, whiteboard lectures, medicine, science

Id: BKOcqlZnCIM

Length: 42min 50sec (2570 seconds)

Published: Thu Apr 08 2021