Cranial Nerve BASICS - The 12 cranial nerves and how to REMEMBER them!

Alright guys, welcome back to another ICU Advantage video lesson and in this lesson I'm going to walk you through the

basics

of these

cranial

nerve

s and really help you understand what

cranial

nerve

s are as well as some different ways of help. Remember which nerve is each before you begin. My name is Eddie Watson and this is ICU Advantage. My goal here with ICU Advantage is to take these complex critical care topics and really try to break

them

down and make

them

easy to understand. Guys, I hope I can do just that and maybe at the end of this lesson we can all subscribe if you make sure to hit the Bell icon and select all the notifications that way, you'll never miss them. a lesson so let's go ahead and jump in here and start talking about what our cranial

nerves

are and essentially what cranial

nerves

are our nerves that originate directly from the brain or the brainstem and when it comes to these cranial nerves, There are actually 12 different cranial nerves and each of these cranial nerves will be paired and present on both sides of the body.

Now we use Roman numerals to number them and we basically number them based on where they emerge from the brain and from the brain. the brain stem when we look at it from front to back, so in order to see these cranial nerves we want to see the lower surface of the brain, which is what we have here and essentially what these cranial nerves do is transmit information. to and from various parts of the body, which will be mainly in the head, in the neck, and then they will have that communication with the brain so that this transmission of information can take place, we have two different types of neurons that we are going to see with these cranial nerves and these are neurons that we call ferrants and efferents.

Now afferent neurons are sensory neurons that carry signals from various sensory stimuli back to the brain. Now our aggressor, our motor neurons, which will carry signals away from the brain. brain have some effect on the muscle or some other target cells and you'll see here in a minute when we go through and talk about these different cranial nerves, but some of these cranial nerves will be ferrant, some of them will be efferent and some of them will actually they're going to be a combination of both, okay, and with that being said, let's go ahead and talk about the different cranial nerves.

Now what I've done here is go over and color each of the 12 cranial nerves to make them easier to identify as I talk about them here, so what I'm going to do is go over them and as we talk about each of these cranial nerves, I'm actually going to use the same color that I've identified on the cranial nerves to help identify where we're talking about, so the first nerve that we're going to start with is set up cranial nerve one and this is going to be our olfactory nerve and this cranial nerve is essentially this one that you see here in green now this cranial nerve is also the first of the two nerves that actually originate in our brain and this is essentially a sensory neuron that is responsible for something that we call smell or what we commonly know as sense of smell.

Alright, the next cranial nerve we're going to talk about is this one here in blue and it's going to be cranial nerve two, which is our optic nerve. and this nerve is the other of the two nerves that are the only ones that originate in our brain and like the olfactory nerve, the nerve cranial to the optic nerve is only a sensory nerve and will be responsible. for vision, then the next three cranial nerves that I'm going to talk about can really be considered as a group because essentially they all have a similar effect and these three cranial nerves that I'm going to talk about are cranial nerves. three right here, cranial nerve four here and actually I'm going to move on to cranial nerve six right here, okay, the first one that I pointed out here in lighter orange, this is the third cranial nerve and this is our oculomotor and this A nerve in particular originates in the midbrain and this is actually strictly a motor neuron and this nerve here actually has a few different functions, one is that it plays a major role in eye movement, but it also plays a role in some autonomic function, such as eyelid elevation. our pupillary constriction, as well as the remodeling of the eye and the lens itself, something we call lens accommodation.

Now, after the third cranial nerve, comes the cranial nerve of something we call the trochlear, this also originates in the midbrain and this is also a motor neuron. and it plays a key role in our eye movement and then we skip over cranial nerve 5 to talk about cranial nerve 6, which is the one in dark orange and this is the one we call abducens, this one actually originates in our ponta medullary. region, but like the last two, this is also strictly a motor neuron and, if you haven't figured it out, this once again plays a very important role in eye movement.

Now, for these three cranial nerves, I didn't really go into depth when talking about the different types of eye movements that they are responsible for. In fact, I'm going to save it for a future lesson where I go deeper into each of these cranial nerves, but just a little bit. Here's a hint for the sixth cranial nerve, this is the one we call abducens, this is because this is actually in charge of abduction which moves laterally to the outside of our eye, so that's where this name comes from. let's talk about cranial nerve number 5, which is the one I skipped and it's right here and cranial nerve 5 is one that we call trigeminal.

Now the trigeminal actually originates in the pons and this will be the first of the cranial nerves that has both the sensory and motor neurons, so it is both ferrant and efferent. Now for the sensory portion of this nerve, it actually deals primarily with two things, the first is our facial sensation and this nerve is actually divided into three parts, this is where the so-called trigeminal comes from, but it also deals with sensation of our tongue and this will be the previous 2/3 of the tongue. Now, when it comes to the motor portion of this neuron, this is where we're going to deal. something called mastication, which are essentially the muscles involved in biting and chewing, so let's go ahead and talk about our next nerve, which will be this one here, this will be cranial nerve seven, which is our facial, this one originates from. of the ponta medullary region as well and this nerve also serves two functions and serves as a sensory and motor neuron for the sensory part of this nerve which this is where we are actually dealing with taste on our tongue so this is there will be flavor in both anterior thirds of our tongue, but this should not be confused with the sensation we just talked about with the trigeminal sensory nerve.

Now when it comes to the motor function of this nerve, there are a couple of different things to deal with one is that it has a primary responsibility in our facial expression, also in the closing of our eyelids and it also plays a role in our salivation and tearing, so basically our ability to produce saliva and tear secretion, and move on, is going to be our next neuron, which is This is going to be this one here and this is actually going to be the eighth cranial nerve, something we call vestibulocochlear. This once again originates in the medullary region of Pontus.

Now this nerve here is going to be primarily an afferent sensory neuron and this one. it plays an important role in our balance and our hearing and this is where we get the name balance is the connection to the vestibule and hearing is the connection to the cochlea and this is where the name vestibulocochlear comes from. This auditory nerve may also be referenced here, so it's important to know that you can also hear this one, so the next nerve we're going to talk about is going to be this one here and this one. one will be cranial nerve number nine, which is our pharyngeal glossus.

Now this nerve actually originates in our medulla oblongata. Now, for this one, you might be able to figure out the areas that it's impacting, which is why it got the name here, gloss, that we know. It means tongue and it also has a fairing that comes from the pharynx, which we know would be our throat, so this particular nerve is actually once again a sensory and motor neuron. Now, for the sensory portion, here again we are dealing with taste, but now When we talk about the posterior third of the tongue, we also deal with the sensation of that portion of the tongue, the sensation of the pharynx and then we also receive information from our sinuses and our chemotherapy and carotid baroreceptors, and this is partially shared.

With cranial nerve 10, which we'll talk about in a minute, the motor function of this nerve is the muscles that deal with swallowing and also helps in our salivation, so moving on to the next cranial nerve, this will be this one. right here and this will be cranial nerve 10, which is what we refer to as the vagus nerve. This also originates in our medulla oblongata, so the vagus nerve is actually longer than any of the other nerves we have, it's absolutely huge. it really comes from the term vagus which comes from the wandering of this nerve, it really wanders everywhere, as you will see here now, the vagus nerve is made up of our sensory and motor neurons, and when it comes to the sensory portion here we are dealing with sensations coming from of the skin around the ear, it also deals with sensations coming from the pharynx, larynx, thorax and abdomen and this will come from the visceral tissues of the body and then it is also involved in taste and sensation from the epiglottis now for its motor functions plays a role in speech swallowing and coughing now also has an efferent effect as part of our autonomic function particularly the parasympathetic nervous system and this is what we can think of as that rest and digest so it will have a diminishing effect here of heart rate, increased gastrointestinal motility and sweating.

The next nerve I'm going to talk about is this one right here and it's going to be cranial nerve 11, something we call the Accessory Nerve now, this one also originates in the oblongata and the cervical spinal cord and as a result, you'll sometimes hear it called as well. This is referred to as the spinal accessory nerve. Now this nerve is strictly a motor neuron and it plays. a role in shrugging our shoulders and our head turning nicely and the last cranial nerve we're going to talk about is going to be this one located right here, this is cranial nerve 12 and something we call the hypoglossus once again, this nerve originates in the medulla oblongata now you can also find out what its purpose is based on its name once again we see that gloss which we know is the hypotongue which we know it means underneath so we are dealing here with a motor function that deals with the muscles underneath the tongue that are responsible for the movement of the tongue.

Well, we covered a lot with these cranial nerves. Let's go over a couple of different strategies and ways to help you

remember

what these nerves are and what their function is. Alright, the first of these ways to help you

remember

these different cranial nerves is a silly little picture that we can draw and the way it works is we start by drawing the number one, now we're going to draw a face here, so the 1 will represent the nose, which we know is our olfactory, then we'll go ahead and draw two eyes because we know that cranial nerve number two is our optic nerve, then we'll do two three like this, about four. and some sixes and these are to help us remember that the third cranial nerve, the oculomotor cranial nerve for the trochlea and the sixth abducens cranial nerve, have to deal with eye movement, then we have cranial nerve 5, which is the trigeminal, Let's deal with our facial sensations now, since we're talking about the face, let's not forget about cranial nerve number 7, our facial nerve, cranial nerve 8, which is our vestibular cochlear, we know that would be a great ear here and number 9, the pharynx glow, plays an important role in our tongue and our pharynx and that's a great addition here we can add the vagus nerve as it plays an important role in swallowing and speaking and while we're here let's not forget about number 12 which deals with the movement of the tongue and finally we are left with cranial nerve 11, which we know deals with shrugging the shoulders and turning the head, so you can see a silly face that we drew here and which really helps us remember. which cranial nerves are dealing with which part now, in addition to this, we also have a couple of mnemonics that can help us remember these names.

Now there are two different ones that I'm going to show you, one is a little older, a more classic version and the other. it's a little bit more up to date, so for the first mnemonic, which is our classic, it goes something like this on the towering peak of old Olympus, a Finn and a German saw some jumps here now. I'm not sure why a Finn and a German want to fuse some hops together, but this saying really goes back a long time and helps us remember the name of each of the hops.cranials, starting from one until reaching twelve.

The key things we need to know here is when we are treating. With this particular mnemonic, this here and this here deal with some of the alternative names for these cranial nerves that I had talked about. Now each of the initial letters and the mnemonic help us remember the initial letter of the cranial nerve name in particular, so here we have, starting from the top down, we have the olfactory, we have the optic, we have the oculomotor. we have the trochlear, the trigeminal, the facial abducens, the next will be the auditory, which we also know is the vestibular cochlear, then we have the glossopharyngeus, the vagus, the spinal accessory and the hypoglossus, so in the old Olympus rises a fan and a German seen.

A few jumps, as long as you can remember that we're dealing with the auditory and spinal accessory, can help you remember the order of those cranial nerves. Now another more modern version that I actually prefer is this one, let's put it here and this one goes sometimes our trusty truck acts strange, it's a very good vehicle anyway now here once again the first letter lines up with the first letter of that particular cranial nerves name now here for this for this cranial nerve and this cranial nerve here you We can see that we have different letters because we are going with the actual name that we had talked about, so once again we have our olfactory or optic motor u ocular, our trochlea, our trigeminal, the abducens, facial, vestibular, cochlear, glossus, pharyngeal, vagus, accessory and hypoglossal nerves, so hopefully. one of these two mnemonics or maybe that drawing I made will help you remember them.

The last thing I want to do real quick here is share another little mnemonic that we have to help us remember whether they are sensory or motor. neurons or actually if it's both, let me go ahead and put the letters here and here we're dealing with s being sensory, M being motor and B being both now the first and this is actually my personal favorite. They say money matters, but my brother says big brains matter more. The other mnemonic that I've heard that some people also prefer is that some say that my mother bought my brother a bad beer, so again, whatever these mnemonics help you remember this or in fact, you can go online and there are others available for both this and just remembering the names of the cranial nerves, some of them may not be pg rated fyi, but the important thing is that you find something that works for you. to help you remember what these cranial nerves are and also to try to help you remember what they function, whether sensory or motor, because there is a lot of information related to these and it really just requires time, energy and effort to record them in your memory to help you know what they are without having to really think about it now, as I said in this lesson, this is a pretty quick overview of these different cranial nerves, stay tuned for the future. lesson where I'm going to break them down more broadly, give you more information about these particular nerves, and go over how we're going to evaluate our patients for the function of these particular cranial nerves.

Alright guys, thank you very much for I really hope you enjoyed this video. If you make sure to subscribe to our channel and leave a like below, also be sure to check out another one of our amazing videos that YouTube recommends here as always, thank you all. Lots to see and have a wonderful day.