12 Cranial Nerves

the human brain controls the rest of the body by sending signals through the spinal cord out through nerves that connect to the muscles and other organs of the body telling them what to do but there are actually 12 pairs of nerves that bypass the spinal cord alt together the 12 cranial nerves so in this video we're going to learn all 12 cranial nerves we'll learn what they do and we'll learn an acronym to help us remember those 12 cranial nerves for any test or class that you have we use some 3D models from anatomy. apppp

to help us visualize what these nerves look like and what they connect to and if you're learning all of the ner system check out my two-part study guide that organizes all this information for you and uh helps you get ready to pass that test or class that you have so let's uh jump to the Whiteboard and get started so our diagram for the 12 cranial nerves is actually an inferior view of the brain so if I take my brain from Anatomy Warehouse here is sitting in my head like this we're actually looking from underneath and

so if I turn this you can see the view that we're looking at all of those cranial nerves in yellow they're sticking off of the Dylon and the brain stem those are the ones that we're learning in this video here are the names of the 12 cranial nerves now at first glance that looks like a lot but we have an acronym that's going to help us remember all of those and get it memorized and that acronym is O to touch and feel a very good Velvet ah now I don't actually have a piece of velvet

here but I do have this CT science sweatshirt which is very soft and velvety Link in the description if you want to get your own sorry to plug that but I I just got this and uh I'm really excited about it and before we get into all of those nerves we're going to take a look at the parts of the brain that we need to know for this video video so we can talk about the nerves a little bit better and what they do first we have the cerebrum which includes the lobes of the brain

like the frontal lobe and occipital lobe we've got the Dian seylon which is the structure that includes the midbrain the hypothalamus and the thalamus I don't have it drawn in a ton of detail here because it's going to get covered up by a few other things next we have the pituitary gland which is sticking off the bottom of the diyon we can see that pituitary gland right here in our model next we have the cerebellum which is going to be sticking off the posterior and inferior side of the brain right here connected to the midbrain

of the dlon we've got the ponds so here's the ponds right here in our model and then connected to the bottom of the ponds we have the medulla alanga which is going to form the beginning of the spinal cord as well if you want to learn more about those structures of the brain I've got a couple videos about the brain that I'll link below as well all right let's get into the actual cranial nerves and what they do our first cranial nerve is going to be the old factory nerve which is going to be all

about smell I just think of an old factory an old smelly Factory as you're driving down the road and olfactory nerve is purely a sensory nerve it's not going to send any signals out to tell any part of our nose what to do it's only going to be bringing information in in fact all of our cranial nerves will be classified as a sensory a motor or a mixed nerve which means it's got some fibers for sensory and some fibers for mixed so the olfactory nerve is a sensory nerve and it's going to carry signals from

the olfactory nerve endings which are hanging down in our nose they pass through the cribiform plate in our skull and when chemicals get up into our nose those sensory nerv nerve endings will detect those and then they'll send a signal back through our old factory nerve to a couple different parts of our brain and so you see there's two stria that split right there and so there's two different parts of the brain that's it's going to send information to to the temporal lobe as well as to the brain stem so the olfactory nerve is a

sensory nerve all about smell all right let's keep going o to touch and feel very good Velvet so we've actually got three O's we're going to start with we got the O Factory up next we have the optic nerve the optic nerve is going to be another sensory nerve but instead of smell this one's going to be about Vision optic or Optical of course is referring to the eye it's sensory only so it's not going to move the eye we're going to have other nerves actually three nerves are going to be controlling the movements of

the eye the optic nerve is only about sensory information so it's only sending signals from the eye to the brain specifically that's going to carry information from the ey's retina and a couple other structures in the eye through the optic nerve back to the occipital LOE in the back of the brain so the olfactory nerve is sensory information for smelling optic nerve is sensory information from our eyes and the third nerve is going to be our first motor nerve and that's going to be the oculo motor nerve which is a pretty easy one to remember

I think oculo means I and motor means motor or it's going to be sending signals from the brain out to tell some muscles or other organs what to do now the ocul motor nerve is going to be controlling most of the eyes movements it's going to include things as well like pupil constriction or elevating the eyelid but there's all these muscles around the eye that the ocul motor nerve is going to control let me grab the eye from my torso model Tori here and you see the eye here and if I turn it you'll see

all these muscles around the eye and those muscles are going to be moving the eye around the oculo motor nerve controls all but two of those muscles that are moving the eye around all right so far we've got three nerves we got the O Factory nerve which is sensory for smell optic nerve which is sensory for vision we got the oculomotor nerve which controls most of our eye movements there's going to be two other nerves that control eye movements the first of those is going to be the next one which is the trolear nerve the

trolear nerve is another motor nerve specifically it controls the superior oblique muscle of the eye which is going to run kind of forward and then it's going to kind of turn it's going to go through like a little pulley system here it's going to turn and it'll help like rotate the eye so whenever you're looking downward or kind of looking inward it's going to help with that movement so we have o o o to touch that's going to be our next one is going to be the trigeminal nerve this is cranial nerve number five also

if you've noticed that each of these nerves start with CN that stands for cranial nerve and they're numbered 1 through 12 of course the trigeminal nerve I have a special way that I remember that that's cranial nerve number five so I think of Tri which means three and gemina or Gemini refers to the twins in like constellations and stuff so Gemini is twins which is two so try plus G gemini or two adds up to five so I just remember that's cranial nerve number five kind of weird but that's how I remember it trigeminal nerve

is a super important nerve that's going to provide sensory information from the face as well as motor control of chewing so sensory for kind of the whole face and then controls our muscles for chewing muscles of mastication now the tri and trigeminal refers to the three branches of the trigeminal nerve here's the three branches the first one is the Opthalmic branch and that's going to be for kind of our forehead and kind of this eye region right in here branch number two is going to be the maxillary nerve which is going to be sensory for

kind of this region above our mouth and includes our upper row of teeth as well those are both sensory branches of the nerve and then finally we have the mandibular nerve which is going to be a mixed Branch meaning it's got sensory and motor information it's going to be sensory for kind of this lower jaw and our lower row of teeth but it's also going to have motor control of our muscles of mastication our muscles of chewing such as our masser and our temper RIS I've got a whole video on the muscles mastication if you

need to learn that check out the link in the description below for that so the trigeminal nerve there's three branches it's going to be sensory for the whole face and that third branch the mandibular branch is going to be sensory for the jaw here as well as motor control of the muscles of mastication or chewing now as I go through all this take some time and pause the video throughout and see if you can remember all those different nerves that we've talked about Maybe cover up that part of the screen right there at the end

of the video I'll have a couple blank diagrams for you to practice this stuff and I also have A&P study cards if you were learning a lot of& content I've got stuff that covers kind of the main topics of& um so links in the description for those a& study cards as well y'all I'm sorry I feel like I keep saying links in the description for all this stuff but the the gist of it is I've made a lot of resources to to help you out I've also got a free A&P Survival Guide that teaches you

how to learn A&P stuff so I'm going to try to stop talking about all these resources I've made but if you're trying to learn A&P I've got a lot of stuff that can help you out and you can find all that down in the description all right let's get back to the video after the trigeminal nerve we have nerve number six which is the abducens nerve this is the other nerve that's going to control eye movements and specifically it's a motor nerve so only controlling movement and it's going to control the lateral rectus muscle that's

going to be a muscle on the side of the eye that's going to take the eye and turn it outward so the right lateral rectus will abduct the eye turn it outward that way the left lateral rectus will abduct the left eye and move it out that way that word abducens is the same roote say abduct which means to kind of move away from the body o o o to touch and feel so we have to have one that starts with an f and that's going to be our facial nerve the facial nerve is going

to be controlling all the movements of our face so if you make any silly faces or smile or or frown or any of those different things you're using your facial nerve to control all those movements take a moment practice using your facial nerve here that that was kind of ridiculous but if it helps you remember it then hey it's worth it your facial nerve is a mixed nerve meaning it has some sensory information but it's not going to be sensory for like the different parts of the face remember the trigeminal nerve was the main sensory

nerve for the different main parts of the face so it controls your facial expressions that's the motor part and the sensory part is that it's going to control the anterior 2/3 of the tongue so Sensations from the tip of your tongue and the middle part of your tongue those are going through the facial nerve the posterior side of your tongue is it's going to be another cranial nerve that we'll talk about in just a minute so facial nerve is a mixed nerve it's going to be for controlling the movements of the face and it's going

to be sensory for the anterior 2/3 of the tongue o o to touch and feel veryy so now we're going to have the vestibulo coclear nerve the vestibul cocar nerve is a sensory nerve and that word vestibulo clear is a combination of vestibule and clear vestibule is going to be referring to the main bony structure of your inner ear it has the semicircular canals which are going to be detecting balance and CIA is referring to the part where detecting the sound so there's actually two branches of the vestibular clear nerve one that's going to go

to the semicircular canals of the ear and one that's going to go to the ca for sound information so this is responsible for hearing that's the clear Branch as well as balance that's the vestibular Branch quick check in before we continue can you remember which of these are sensory which are motor and which are mixed ol Factory is sensory optic is sensory ocul motor is motor trolear is motor trigeminal is mixed abducens is motor facial is mixed and vestibular clear is sensory all right cranial nerve number nine is going to be the glosso fenal nerve

glosso like glossery it's referring to the tongue actually I don't know what a glossery in a book has to do with the tongue per se but glosso means tongue and fenal which is the fairings or the back of the throat the glosso fenal nerve is going to be a mixed nerve it's going to control some muscles involved in swallowing and saliva production it's not the main muscle that's moving the tongue but it's going to control some of the other structures that are involved in that swallowing process and it's going to be sensory for the posterior

third of the tongue so like the back of the tongue if you remember the facial nerve was sensory for the anterior 2/3 of the tongue and then the glossop farial nerve is sensory for the posterior 1/3 of the tongue up next we have kind of an amazing nerve it's cranial nerve number 10 it's called the vagus nerve and that term vagus is actually Latin for wandering same root as like Vagabond a person who wanders now why would we call this the wandering nerve well if you notice all of the other cranial nerves that we've looked

at they're all controlling things in the face like your eyes or your nose or your facial expressions the Vegas nerve however is actually going to travel from the brain and go down throughout kind of the whole rest of the body it's going to go down to your digestive organs it's going to go to your heart it's going to go to your lungs like it's wandering throughout the body it doesn't literally wander like it's not moving around but it it connects to Parts throughout the body the Vagas nerve is a mixed nerve it's also the longest

nerve in the body it's longer than any of the other spinal nerves that you have longest nerve in the body pretty cool so what does it do it's going to be your main parasympathetic nerve the parasympathetic is part of the autonomic nervous system which is controlling things like heart rate and breathing rate and different things that we don't consciously control all the time it's going to control like your digestive process things like that and parasympathetic is opposite of sympathetic sympathetic is your stress response parasympathetic is your rest and digest response so whenever you're relaxed this

Vagas nerve will be active telling the different organs what to do whenever your body is in a relaxed state it would slow your heart rate slow your breathing rate increase your digestion things like that that your body does whenever you're not so stressed in addition to that it's also going to provide some sensory and motor input to your throat and your voice box or your larynx if you remember one thing about the vas nerve though remember that it is your main parasympathetic nerve for most of your body and it also does sensory and motor control

of the voice box and the throat all right we have two more cranial nerves o o to touch and feel very good Velvet ah and the a there is a and H the a for accessory nerve the H for hypoglossal nerve so let's take a look at the accessory nerve next the accessory nerve is going to help control two specific muscles one is the stero clyto mastoid the other is the trapezius muscle so your sternomastoid goes from the back of the skull right here it's going to connect to the the sternum and the clavicle right

here it's going to help with movements like moving your head down kind of like this so that's controlled by that accessory cranial nerve it also controls the trapezius muscle which is this large muscle right back in here that's going to do a lot of kind of like shoulder movements and stuff so when you elevate your shoulders your accessory nerve is helping out with that also when I was reading about this there's some controversy about whether the accessory nerve is truly a cranial nerve or really actually a spinal nerve if you look at the diagram it

actually connects down to parts of the spinal cord right here and they're kind of saying like these Beginnings right there actually part of the Vegas nerve potentially so any textbook that I've looked this up in it includes the accessory nerve as one of the cranial nerves so that's probably the best way to remember it as far as that goes but just know that some people would really classify this as a as a more of a spinal nerve than a true cranial nerve finally we have our 12th cranial nerve which is going to be the hypog

glossal nerve the hypoglossal nerve is a motor nerve and it's going to control most of the movements of the tongue your tongue is a muscle there's also muscles connected to the tongue so all those different movements of the tongue that's going to be your hypo glossal hypo means under glosso means tongue so this nerve means it's the the nerve under the tongue because think about the tongue is attached to the bottom of your mouth and so that's where a lot of those muscles are that are moving that tongue around real quick let's review those 12

cranial nerves using the model from anatomy. apppp so we can kind of see those thre dimensionally a bit better first we've got the old factory nerve right here which is of course getting information from your nose and sending it to the different parts of the brain here we've got the optic nerves and those are actually going to cross each other it kind of makes an X so your right eye is going to be sending information back to the left occipital lobe your left eye to the right occipital lobe and that's where that signal crosses in

there cranial nerve number three is the oculomotor nerve that's going to be this one right here in blue and then we've got the trolear nerve which is this really thin one in green right there and then of course you've got the abducens nerve right here which is cranial nerve number six those three nerves ocul motor trolear and abdin nerve those are all controlling eye movements but you can see where they originate is all different the oculomotor is kind of coming from right in here in the Dylon the trolear nerve is actually going to kind of

wrap around to the back right in there and connect and then the abducent nerve it's connecting down here kind of to the top of the medulla right between the medulla and the ponds we've got the trigeminal nerve which is going to be this really large nerve right here it's going to after this part where it's cut off right there it'll Branch off into the three branches that's cranial nerve number five abducens with six number seven is the facial nerve also coming off the ponds and then we have the vestibulo clear nerve that's going to go

to the ear to the vestibul and the ca of the inner ear then we have the the glosso farial nerve we've got the vagus nerve right here and we have the accessory nerve which is going to have these branches as well as these that kind of come from the spinal cord down here and then a bit more anterior to those is going to be that hypoglossal nerve which controls the tongue movements so those are all the nerves and you can see those kind of three-dimensionally on the anatomy. apppp model so those are the 12 cranial

nerves now just by watching up till now in the video it doesn't mean that you have these committed to memory and memorized you've got to practice them in just a moment I'm going to give you a couple blank diagrams can use to practice these and if you need to learn this like for a gross anatomy class at med school you just really need to know like what each of these connects to like what part in the brain it connects to and the and the really kind of deeper anatomy of it then check out anatomy. apppp

Link in the description for that as well as a coupon code you can use to get 10% off if you don't need that level of depth but you're learning all of the nervous system check out my two-part nervous system study guide there's links in the description for that as well that's going to break down all this information organized for you and help you learn it really well for your test or for your class all right here's a blank diagram take a moment pause the video see if you can go through and identify each of the

cranial nerves that we learned as well as whether they're a sensory motor or mixed nerve as well as what they actually do all right here are the names of those nerves so you can check and see how you did now if you did that you're partway there here's something a little bit tougher I'm going to take away the lines as well as the color coding pause the video now see if you can identify all 12 cranial nerves as well as what they do all right and here's the answers back so you can check and see

how you did thank you all for watching and special thanks to my patrons on patreon who helped support the channel help me continue um making these videos and helping you learn an Adine physiology like I said I've got a lot of links to different things down in the description so check out those if you want more help in learning anatomy and physiology and uh I'll see you in the next video bye-bye