Cranial Nerves Lecture Notes PDF

We are going to cover the cranial nerves in this lecture. I'm sure you'll be happy to know that this is the last classroom. All right, so primarily what we need to know is the organization of the cranial nerves, what they do, what kind of information they carry. And then anatomically, how they're or...

We are going to cover the cranial nerves in this lecture. I'm sure you'll be happy to know that this is the last classroom. All right, so primarily what we need to know is the organization of the cranial nerves, what they do, what kind of information they carry. And then anatomically, how they're organized. So what do they, what exit, cranial exit do they leave, and so forth, okay? Okay, so cranial nerves introduction, what are they? There are 12 pairs of cranial nerves, right? So 24 in all, and they're going to come out of either, well, the brain stem, right? So here's the brain stem that we have seen before. Here are our mammillary bodies for reference. Here's the pons, and here's the medulla. So they're going to be coming out in relationship to those structures. So which motor pathways travel through cranial nerves? If you recall, we did this our last block. It's going to be the spinal, or a cortical bulbar tract, sorry. Cortical bulbar tract, right? It's going to bring motor innervation from our cranial out. And then how sensory information from the head and neck transmitted. It's going to be via these cranial nerves here, right? And so we'll have those unipolar neurons within these different ganglia that we'll talk about here. And here we can see one of the largest, which is going to be the trigeminal ganglia. So sensory and motor communication are carried within this. And this is going to include both visceral and somatic information. The nuclei for all cranial nerves, except one and two, are going to be located within the brain stem here. And this is kind of a really nice view of that information, right? So each of these different colored globs, I guess, would be a nuclei for the different cranial nerves. So they're pretty complex. I don't expect you to know all of these in their organization. So they're going to travel through openings in the bottom of the crania, in the basal crania, which we've actually already seen before. So we'll be recalling that information. Communication occurs between cranial nerves. And what I mean by that is they're basically form of plexus. So while we might talk about these cranial nerves individually and what they carry within them, fibers will travel alongside other nerves, right? So for example, cranial nerve 5 can send some fibers to travel alongside fibers from, for example, I don't know, we'll do facial. This is probably not a perfect example. But so we're going to have these plexuses formed. So again, while we talk about these individually, they will meet up in terms of their entire structure, okay? You'll note that cranial nerves are indicated by Roman numeral. We do not use Arabic numbers for these. So if you don't know your Roman numerals, 1 through 12, now is the time that you will learn. All right, so in terms of the function, I really like this image. It kind of sums up what each of these do, primarily cranial nerve 1 through 12. So you might want to resort back to this. But in terms of fibers, cranial nerves are going to carry different information. So it's going to be in terms of motor. We might have somatic motor, right, to voluntary muscles of facial expression. And then visceral motor. So recall that that's going to be autonomic. This is going to send information, specifically parasympathetic information, to the glands of our face and neck, right? So for example, we have our salivary glands. We have our lacrimal glands and so forth. And then sensory fibers, right? Afferent arriving at the central nervous system here. We're going to have somatic sensory, so just general touch from the skin and then also mucous membranes. So that's going to be the tissue that lines your nasal cavities and your oral cavities. And then visceral sensory. So this is going to bring information from what's going on inside our body to the central nervous system, right? So visceral sensory. This is, of course, going to be parasympathetic innervation. We are also going to have information coming in from our lungs, heart, and GI tract, right, coming through the cranial nerves. So we already talked about cranial nerve 10 and the role it plays in the autonomic nervous system. And then we'll have special sensory. So this is going to carry, these are going to carry information about taste, smell, vision, hearing, and balance, right? And these are going to be important for kind of interacting with everyday situations. All right, so let's label these here. I think one way to do it is just to go in order from 1 to 12. And then you can either just use the Roman numeral or you can use the name of it or both. I think knowing the names are really helpful in terms of determining what they do, so I'm going to do just one side here. So here's cranial nerve 1, olfactory is going to come out and communicate via that cribliform plate. We go straight down a midline. Here is cranial nerve 2, this is our optic nerve. Here's our optic nerve 1, 2, and 3, and it's going to be right behind there. So OOO, olfactory, optic, and ocular motor are all nice in a row. For 4, we're going to go lateral here. So 4 is this little guy right here, often hard to find, quite petite. That is very different from cranial nerve 5 to the side here. Cranial nerve 5 is trigeminal, it splits into 1, 2, 3 nerves pretty quickly and has this large trigeminal ganglion here. And then for 6, we're going to go back to the midline. So here is 6, so 6 is going to provide motor innervation to the eye. And we'll come back to that. So again, 1, 2, 3, 4, 5, and then back to the middle for 6. 7 and 8 are going to be right here. I know they look like three different nerves, but they're not. So 7 and 8, so we'll do 7 here. 7 is going to be the facial nerve. Facial nerve is going to be one of the harder ones to learn, because it does a lot. 8 is vestibulocochlear, right here. Okay, one more there, so cranial nerve 8. They're going to exit out the same opening, at least initially here, which is going to be the internal acoustic meatus. And then we're going to have 9, 10, and 11, all right in a row here as well. So 9 is going to be this one, is going to be glossopharyngeal. If that tells you what it does, it's going to go the tongue and the pharynx, right? 10, we know that's a biggie, right? 10 is going to provide parasympathetic innervation all over the place. And then 11 is going to be special. Some people don't call this a cranial nerve, because at one time, way a long time ago, evolutionarily, this was just a spinal nerve. You can see that it's actually going to have fibers from the spinal cord, come up and contribute. It's going to go through the foramen magnum and then out of our cranial vault. So that's pretty crazy. It's going to exit with 9, 10, and 11 out the jugular foramen. And then for 12, we're going to go back kind of to the midline on either side of the pyramids here. 12 is going to be the hypoglossal. Hypoglossal, one of the big things it does is innervates the muscles of the tongue. So glossal will help you with that. So 1, 2, 3, 4, 5, and then 6 back to the midline. 7 and 8 are going to run together. 9, 10, and 11 are also going to run together. And 12 is back to kind of the midline on either side of those pyramids. So that is our location. OK, so I like to kind of start out with the big pictures. You'll notice that I skip around just a little bit in terms of what the numbering, right, because I think more kind of organizing them by function is more helpful. And this is going to have that should be there. OK, so olfactory nerve is going to be for smell or special sense smell. That's all it does. Optic nerve is going to be for vision. That's all it does. Ocular motor is going to move most of the eye muscles. In fact, it's going to move four of the six eye muscles that we're going to cover in our next lecture. So we'll get into that more deeply then. Trochlear nerve is going to be creating on our floor. And it's going to supply one muscle, which is going to be our superior oblique muscle. So creating on our floor. Name trochlea because this little structure right here, this little sling, is actually called the trochlea, which is one of the components of this superior oblique muscle. And then we're going to skip to cranial nerve six. We did skip five so far. This is going to be the abducens, or abducens nerve. So cranial nerve six is going to also move one of the eye muscles. This is going to be the lateral rectus. So the lateral rectus would be, we have a little branch of it here and here, been reflected, and that is going to move your eye in the lateral direction or to abduct your eye. So abducens is going to help you abduct your eye. So we have three nerves right here that are going to help with eye movement or provide eye movement. Smell for number one and vision for number two. So let's take a look at these more specifically. All right, so our olfactory nerve is going to be located right here. In this view, we can see that the cribriform plate is located right here. Those openings in the cribriform plate are actually where our olfactory nerves are going to extend through. So our olfactory nerves are going to be these nerves right here that are going to meet with the olfactory bulb. So in terms of our cranial nerves, this is what the nerves are. They're meeting with the olfactory bulb here. And then as information goes back towards the central nervous system, they're going to go along the olfactory tract. So when we look at it here, we see how the olfactory bulb and the olfactory tract and then the nerves would be communicating with the bulbs here. So it's a special sensory. That's all it does. These are going to be the anatomical portions that you need to be familiar with. So we talked about the nerves, the cribriform foramina, part of that ethmoid, olfactory bulb and tract. So conditions associated with pathologies or if this nerve is not working are going to be anosmia, right? Anosmia is going to be partial or total loss of smell, right? So if this nerve is damaged, this is what we will be the result. All right, pretty straightforward. Our optic nerve is going to be our cranial nerve two, right? So optic nerve, it's another special sensory nerve, just special sensory, and it's going to be vision, right? This is going to, and we noted that cranial nerve one and two have their ganglia outside of the brainstem, right? Their ganglia are going to be located in the posterior aspect of the eye, right? So think about those neurons that communicate between those like lower, not lower motor, but our primary sensory neurons and secondary sensory and so forth, right? The ganglia is going to be the back of the eye, specifically the retina. And so when we look at this image, it's important to note how it is organized. So our optic nerve is going to be the structure that goes into the eyeball, right, through that optic canal. We can see that right here in this image, nice and circular for that optic nerve. These nerves are going to cross and the information is going to cross as well. We will get to this when we do vision as well at the optic chiasm. So the optic chiasm is this structure where they cross. And then the optic tract is going to be that specific portion that communicates with the central nervous system itself. And so when we look at this image here, this is going to be the optic nerve up here. Back here is going to be the chiasm or the optic tract. So it's important to keep those separate. Anopsia, let's see, anosmia, anopsia with the P is going to be when we have our visual defects radiated to damage to the optic nerve. Again, we're going to look at the complexity of these visual fields and so forth, how that information gets back to our occipital lobe, as we already talked about before, when we talk about the eye more specifically. All right, so ocular motor, it's lovely, tells you exactly what it does. This is going to be one of three nerves that are going to go through the superior orbital fissure, three cranial nerves here. So if it moves the eye, if it's a cranial nerve that is going to move the eye, it's going to go through the superior orbital fissure, right? So ocular motor is going to, again, move four of those six extrinsic eye muscles. That means outside the eyeball. So we have some on the inside as well that are going to be innervated differently. So we're going to have the medial superior, inferior rectus muscles. Rectus just means they are straight attached to the eye. We'll cover these again when we do the eye. And then also our inferior oblique muscle, which is coming in at an oblique angle. And then finally, our levator palpebrae superioris muscle, which is going to be right here, helps us elevate the eyelid. Super important for allowing our eyes to function well. They are all going to be innervated by the ocular motor nerve. It is also going to have visceral motor fibers running through it. So somatic motor and visceral. That is going to be specifically related to pupil constriction. So this cranial nerves allows us to constrict our pupil. That is going to be the ciliary muscles that are going to, I'm sorry, the pupillate sphincter muscles that are going to be associated with that. And we have our ciliary muscles, which are going to help us with lens accommodation. So two different muscles in the eye, the ciliary lens combination, and then our pupil sphincter muscles that are going to be controlled by ocular motor. Okay, and so if we kind of look at this image here, we can see that our cranial nerve three nucleus, nuclei, are right here. We're going to follow those fibers through cranial nerve three. And we can see it splitting into different directions, giving off fibers to the different muscles that it helps innervate. We will also have that visceral motor go through a ganglion. One of those four ganglion in the cranial that we talked about that will help provide autonomic innervation. This is going to be our ciliary ganglion right here. So again, our ciliary ganglion. Some of the fibers from cranial nerve three are going to go through there. And they are going to extend then to this muscle that will help us dilate or constrict, excuse me, to constrict the pupil. All right, and again, they're going to go through the superior orbital fissure. So to kind of contextualize this, we're going to look at this individual here. Who's going to have, whoops, have some damage to their ocular motor nerve. Right, so conditions caused by this. Difficulties with eye motor function, not a big surprise there. So first off is pitocis. Pitocis is one of our upper eyelid droops. You can see that right here. See how this individual can pull up on the eye? But it's going to drop back down that eyelid, it cannot be elevated. So that's the levator, palpibre superioris. Parallis of most of the eye muscles leading to strabismus. So that means really double vision because you can't make your eyes travel in the same direction to create our normal visual field. We can move it laterally, though, because we can use our lateral rectus via that troch, that abducens nerve, and we can move it immediately due to the inferior oblique helping us out, or superior oblique, excuse me. Those are innervated by different nerves, right? So strabismus, our eyes are not parallel. Diplopaleia is going to be that double vision, right? That's going to be caused by that strabismus. Difficulties focusing, and then we will also have pupil dilation, which you can see in this image, so this individual cannot constrict their pupil despite the light in the room. So all of these are specific to ocular motor damage. Our trochlear nerve moves the eye, it's going to go to one muscle. It just has somatic motor, and it's going to go through that superior orbital fissure, right? We're going to move one muscle here, it's the superior oblique. That the superior oblique was still functioning in that individual that we just saw, so they were able to look medially, and we'll explain that when we get to the eye lecture. If we look at the crayonar for nucleus, we see it right here, and we see that nerve exiting, going right through that superior orbital fissure, right to that superior oblique muscle to innervate it. If this muscle is damaged, we will have some strabismus related to ploplia, because again, this is going to make it a little bit more difficult. It's going to make it difficult for us to move our eyes in the same manner to not have double vision. All right, moving along, abducens, right? We skipped five, so we're going to six because it moves the eye, and it's going to follow the same pattern that we've seen. Recall that our crayonar six is going to come out at the midline, and specifically between the pons and the medulla. So here is the nucleus where those motor neurons will be located. They're going to send their fibers out this way, up through that superior orbital fissure. We kind of lose it a little bit right here, but you can see that this is wrapping this way and innervating that lateral rectus muscle. It's been cut and reflected. This is where it would attach, right? So lateral rectus via the abducensinear lateral rectus means it's going to help us abduct, right? So superior orbital fissure, just like all those other motor innervation to the eye, somatic motor. Again, conditions caused by this can be diplopalea. So if you are trying to look laterally with the eye that is damaged, it's not going to move, but your other eye will. So you're not going to be able to, you're going to have double vision as a result. All right. Next, we're going to do trigeminal, facial, and vestibular cochlear. I think these two are the more challenging. They're going to do a lot of stuff, okay? So big picture, cranial nerve five is trigeminal. It's going to provide sensory innervation to the face, scalp, and the anterior two thirds of the tongue. This is somatic sensory. It is also going to provide somatic motor to the muscles of mastication, trigeminal for mastication. The facial nerve is going to do movements of the face and scalp, so muscles of facial expression and the scalp. And then in addition to that, it's going to do two of the three salivary glands. Ironically, it's not the one it travels through. It's going to travel through the parotid gland, but it doesn't innervate the parotid gland. It is also going to do special sensory taste on the anterior two thirds of the tongue. So if we do this as the tongue, anterior two thirds, we're going to have the trigeminal, T for trigeminal, doing just sensory. And facial is going to do special sensory of the anterior two thirds. And then when we get there, motor is going to be cranial nerve 12. All right, vestibular cochlear, love it. It's going to tell you exactly what it does. Vestibule and cochlear are going to refer to balance in hearing. Cochlear is going to refer to the hearing aspect. Balance is the vestibule. These are different structures within the ear that we will visit soon. All right, trigeminal nerve here, right? So this big guy here is going to be coming out of the crania and almost immediately we have this trigeminal ganglion. Recall that this is going to do a sensory. So we're going to have those unipolar neurons in here for sensory, sending out fibers in both directions. But those fibers might be going out one of three routes for those that trigeminal ganglion or trigeminal nerve, right? So primary somatic sensory for the head. We're going to have this organized in a nice way. So the superior most aspect of the face is going to be through the ophthalmic nerve here. The maxillary area is going to be via the maxillary nerve and then the mandibular portion is going to be go do the skin over really the mandible. So three divisions of the trigeminal ophthalmic. It's going to travel through that superior orbital fissure that we've already talked about with those motor, eyeball motor nerves. But it's going to travel superiorly here mostly and send out branches up here. All right, it is also going to innervate the lacrimal gland, which we see right here to help us cry. The maxillary, it's going to travel through the foramen rotundum. Right here is our foramen rotundum. And then it's going to go into, kind of back into the maxillary sinuses in this area too, and then also extend out the infraorbital fissure, right? So our superorbital fissure was up here opening, or foramen, sorry, in superorbital foramen, an infraorbital foramen. I made you learn this a long time ago for a reason. So the ophthalmic nerve is going to provide sensory via that superorbital foramen. Maxillary is going to come through the foramen rotundum back into the maxillary sinuses, provide some stuff there. And then we're also going to come out the infraorbital foramen to provide sensory in this area. Notice that some of these are going to go to the teeth as well. And then our mandibular nerve is going to do something similar. It's going to come down and it's going to provide innervation to really the lower facial area. It is going to exit via the foramen ovale. So foramen rotundum, that nice round opening, the foramen ovale, if you recall, is that oval opening. Okay, all four of the cranial ganglia are going to be associated with cranial nerve five. And so in this image we can see that ciliary ganglia right here. We can see the pterygopalatine ganglia here. These are the pterygoid processes, right? Put a P there, and the palatine bone is going to be posterior here, so pterygopalatine. We are also going to have the submandibular ganglion associated with that, and then the otic as well. Okay, so pretty straightforward here. This is a different view now. Here's our trigeminal ganglion with our nice unipolar neurons in there, communicating both ways. We're going to have our ophthalmic branch, again, do our superior face. That is going to go through that superior orbital fissure. We are going to have branches traveling up here to the forehead, and really some on that superior aspect of the nose. We are also going to provide innervation to the cornea of the eye, which is going to be one of our eye structures, and then skin in these locations. Notice that the superior nasal cavity, that's going to be that kind of internal membranous epithelium here. So you can note that right here. And then also some other sinuses, specifically the paranasal sinuses. All right, we know this superior orbital fissure, and then the super orbital foramen is where most of those fibers are going to leave. Okay, maxillary, you can see the areas that it will innervate here. It's also going to be part of that nasal cavity as well, and the upper lip, and then kind of up along the lateral aspects of your face. This nucleus here is going to be called the principal sensory nucleus. Notice it's quite big, right? You're going to be bringing in a lot of innervation to this area from that trigeminal nerve from the face. If we follow the maxillary branch, though, it's going to go in this way. Remember, it goes out that foramen rotundum, nice and round, back in to this area, and exit finally out that infraorbital foramen. Don't forget that as it travels through here, we can also provide innervation to those maxillary sinuses in the palate. So maxillary sinuses are those big spaces that are located within our maxilla here, and that should make sense because that's where our innervation is traveling. where our innervation is traveling. Finally, it is going to help us innervate the maxillary teeth here, right? innervate the maxillary teeth here, right? So it's an important nerve to know about if you are working on teeth. All right, so foramen rotundum, and then out the infraorbital foramen right here. All right, final branch here, at least. We have our mandibular nerve, right? So that's going to come out that trigeminal. It's going to go out the foramen ovale, then it's oval one here, and send fibers inferiorly here. I'm talking about as if it's motor, but I'm just going in direction towards the face, right? It's going to cover the skin over the mandible, up along the side of the head here. We are going to cover the ear a little bit here. Recall that the rest of the information here is going to be coming out that cervical plexus that we've already talked about. And it is going to do, let's see, somatic sensory is going to do the temporomandibular joint. So right here, it's going to be hanging out around here. And then the anterior two-thirds of the tongue, right, for just our somatic sensory. Special sensory is going to be cranial nerve seven. Somatic motor to the muscles of mastication now, which is pretty important. So the muscles of mastication are going to be, if you recall, we have our temporalis. We are also going to have our masseter and our buccinator in this area. We also have a few smaller ones as well. The anterior belly of the digastric, the tensor belly palatini, and then the tensor timpani. And these are going to be muscles in the ears. Well, this one is. This is just a tiny little muscle that we actually don't learn. Oh, I think I do. We do. Later on. Don't worry about it right now. All right. And then finally, we're going to talk about, oh, I have this image here. Here's our muscles of mastication, right? And they're also including the pterygoid muscles here. So our medial lateral pterygoid, our masseter, and then our temporalis are shown in this image. shown in this image. Okay. Our trigeminal nerve. All right. If this is damage, we are going to have something called trigeminal neuralgia, right? And this is going to be intense pulsating pain, usually resulting from inflammation of one of these three components, right? of one of these three components, right? So usually it's going to be a branch of the trigeminal that is going to be impacted, causing pain. Okay. Our facial. Here comes the big guy here. Facial nerve. Facial nerve is going to primarily be somatic motor, right? But it's going to do a lot of other things as well. So though all those muscles of facial expression, well, that sounded good. All of the muscles of facial expression are going to be done by your facial nerve. nerve. It is also going to do several glans, special sensory tastes, right? special sensory tastes, right? To the anterior two-thirds of the tongue. And then we're going to have a little bit of sensory. We're not really going to worry about that today though. And it also takes a very complex route through the crania here. So it's going to travel through that internal acoustic meatus with the vestibular cochlear nerve, cranial nerve eight, right? So it's going to go into the inner ear stuff. That's going to send off a few branches and then it's going to meet or form this geniculate ganglion. Geniculate ganglion is going to have our sensory neurons in there and it makes this kind of U-turn out, okay? So we're going to make this U- turn within those inner ear structures. within those inner ear structures. Some branches are going to come out right here, which is going to be the stylomastoid foramen. Some branches are going to make another U-turn and go a different route, okay? So again, it's pretty complex here. And I think we have a different image for this. All right, so in terms of the muscles of facial expression, these are going to kind of probably remind you of that cervical plexus that we've already covered. But let's take a look here. So muscles of facial expression and the scalp. In this, in addition to this, we're going to enter the stylohyoid from the styloid process down. So that's going to be right here. And then the posterior belly of the digastric, which is going to run right next to that, right? next to that, right? To the mastoid process. So here we have, let's see, I'm going to make sure I get this right. We're going to have the, excuse me, the facial nerve come out. We have our geniculate ganglion here and then we have different routes that this information can travel. We are doing the muscles of facial expression. So we're going to go down out that stylomastoid foramen and start to branch. We have several branches that are named for where they're going. going. We have our posterior auricular branch that's going to go behind the ear, posterior auricular. We're going to have our temporal branches up this way, kind of along the anterior border of the temporalis muscle. Our zygomatic branches too, our zygomatic structures, right? Remember that zygomatic is major or minor. We have a buccal branch to our cheek right in here, right? And it's going to go a little bit further and innervate way out here. And then we're going to have our mandibular branch coming down and then we're going to have our cervical branch, our neck branch, okay? cervical branch, our neck branch, okay? So they should, they're named for what they do in terms of their motor innervation. Okay, in terms of our visceral motor, we're going to have two of the three salivary glands innervated by this muscle. And so importantly, we're also going to have the lacrimal gland as well. And one of the things that, the reason I kept this image on here is because we are able to see our salivary glands here. So we are going to have, if we talk about just starting superior to inferior, going from our lacrimal gland innervation, we can't see it, but it will be traveling through, let's see, let me try to get the right fibers here, we're going to have our cranial nerve seven coming on out. seven coming on out. We're going to send visceral motor innervation two, and this is going to be autonomic, right? So it's going to be parasympathetic to our tericopalatine ganglion. This is where we will synapse and send our post-ganglionic fibers to our lacrimal gland right here in the eye, right? eye, right? So we have our tericopalatine ganglion involved in this. Going a different route, we're going to have our fibers coming out, go through that geniculate ganglion, travel on down here, and then we're going to join up with this big, not big, this important nerve called the corded tympani. The corded tympani is going to travel along here and synapse in the submandibular ganglion and send innervation to the submandibular and sublingual glands. These are paired, we're only seeing the left side. On this route here, we are going to have the facial nerve. When we look at the facial nerve that provides somatic motor innervation, it actually travels through, right on through, within the parotid gland, but doesn't provide innervation, which I think is crazy. That's just going to be to these two salivary gland glands, not the parotid gland. All right, so in terms of more specific nerves, we're going to have the greater patrosyl nerve right here, allowing innervation to the lacrimal gland via the facial, and then we're going to have the corded tympani bringing motor innervation, visceral motor, down to the submandibular gland to send fibers then to our sublingual and submandibular glands here. Facial is hard, we've just got a lot going on. All right, so special sensory, this is going to provide taste to the anterior two-thirds of the tongue. I really like this image, even though it's mostly taken up by the branches of the trigeminal here, we do have our visceral sensory to the tongue shown. So if we start here, there's that geniculate ganglion, there's our our unipolar neuron, sensory neuron. We're going to go this way and we're going to make this crazy loop here. We're not going to go out and innervate the muscles of facial expression. We're going to continue on this way. We're going to go down through that corded tympani and join up for other fibers from the sensory from the trigeminal ganglion. the sensory from the trigeminal ganglion. Come on down and provide special sensory, right? special sensory, right? So special sensory to the anterior two-thirds of the tongue is seven. I'm just going to do the number and then our normal sensory, somatic sensory, is going to be five. All right, vestibulocochlear, pretty straightforward. We'll get into this a little bit more deeply later on, but vestibulocochlear refers to these structures that help create our inner ear. these structures that help create our inner ear. So this is actually going to be the vestibule right here in this picture. So vestibulocochlear is going to be the cochlea right here where we interpret sound, right? interpret sound, right? So special sensory only, the vestibulocochlear nerve is going to carry and it's going to exit the cranial vault. So inside via that internal acoustic meatus you can actually see cranial nerve seven running alongside of it here. It's going to come down and it's going to go one of two places. We're either going to go to the cochlea as a cochlear branch of cranial nerve eight or the vestibule, the vestibular branch of cranial nerve eight. And they're going to synapse either in the vestibular ganglion or the spiral ganglion. When we do the ear we will look at these more specifically. You can see the vestibular ganglion here and you can see where the spiral ganglia are located. Notice again that we're going to have these nice, actually we have these bipolar neurons because it's sensory but it's special sensory. So yay there are those final bipolar neurons that we've been talking about for a while coming out on either side not those unipolar neurons. If we have damage to either of these we're going to have loss of hearing and then loss of balance right to different degrees. Loss of balance can lead to nausea, vomiting, and dizziness. Okay all right we're getting their big picture of cranial nerve nine and ten. We've already visited this but we're going to see it again. All right so glossopharyngeal is going to provide innervation to the tongue right and then the pharynx as well so glossopharyngeal. So it's going to be these more posterior structures so its impact on the tongue is going to be in that posterior one-third of the tongue. So in terms of what it does we're going to have somatic motor. It's going to aid in swallowing primarily through these two muscles which we will look at when we do the pharynx so it's superior constrictor muscles. One of the salivary glands which is going to be the last one left the parotid gland and then both somatic taste so special somatic special sense via taste and somatic sensory to the posterior one- third of the tongue so both kinds of sensory are going to go through the cranial nerve nine from the back of the tongue and then we're going to have some it's going to monitor the blood via the carotid body or the carotid sinus and this is going to be that autonomic innervation. Okay vagus is going to provide motor innervation to muscles of the throat primarily the pharynx and the larynx and esophagus sensory to ear structures believe it or not and then visceral motor and visceral sensory to and from the thoracic and abdominal organs because this is a very big important autonomic nerve. Okay let's take a look I love this picture it's beautifully detailed and beautifully drawn here okay so the glossopharyngeal nerve tongue and pharynx is going to pass through the jugular foramen so 9 10 and 11 are all going to go through the jugular foramen and let me see where I'm looking at it here because here we go there's our big jugular it's a big jugular foramen right there jagged jugular here's our carotid canal we can see how it comes in at that angle that canal and we're going to do swallowing both visceral we're going to do visceral motor to that third and final salivary gland special sensory and somatic sensory to the posterior one-third of the tongue also somatic sensory to the soft palate and the pharynx so soft palate think about back behind the palate the palatine bone and then pharynx is the back of the throat and then visceral sensory via that carotid body and this is I think a really nice place to show that the carotid body is going to be located right here in this location where our internal jugular and our external jugular internal jugular and external jugular split we're going to have this little structure here and we're going to have our innervation from that information sensory information somatic sensory information visceral sensory information come in from that structure in through our cranial our glossopharyngeal nerve which we can see is coming up this way it kind of looks like it's going into the carotid canal but it's not it's going via the jugular foramen so there we go and here's cranial nerve seven if you want to see that crazy route that it does here's a stylomasteroid foramen and here it is going anteriorly here all over the place right okay more specifically different view here's cranial nerve 10 or here's cranial nerve nine excuse me you can see that it has actually two ganglia associated with it so does the vagus nerve so we have a superior and inferior ganglia we're going to provide somatic motor to these structures in the in the pharynx which is going to be this region right here we have our nasopharynx oropharynx and laryngopharynx but if we follow that red dot red line down it's going to come on down here we see it going to the tensor valley palatini oh it's the stylopharyngeus excuse this is the stylopharyngeus okay and then our superior constrictor muscles are going to be right here in the back of the throat as well in terms of visceral motor to the parotid gland the final gland which is going to be located kind of right in front of your ear we can see those fibers coming in it's the red dotted line follow that through it's going to join up with other nerves to get to the parotid gland here we have the otic ganglion this is where our motor fibers are going to synapse with post-ganglionic fibers and it's complex route but we're going to get to that parotid gland eventually here right so again visceral motor parotid salivary gland takes a very complex route to get there it's going to travel through like the middle ear and it's going to go through this lesser patrosyl nerve we've seen the greater patrosyl nerve earlier but it's going to synapse in that otic ganglion okay our sensory so all kinds of sensory craving through traveling through here all right so special sensory we can have that taste on the back of the tongue somatic sensory we're going to have just normal sensory on the back of the tongue special sensory somatic sensory and then we are going to have sensory from the pharynx right so pharynx basically just the back of your throat here we can see those fibers coming down we're going to be shown in blue again i know i'm going the opposite way of the information this is just how it works in my brain we're going to synapse or we're going to have excuse me our so our sensory ganglion sensory neurons in these ganglia here i need to slow down and information is going to come in here to the back of the throat and to the back of the tongue right we can see that piece coming down here to the carotid body and helping with our visceral sensory information right so carotid body is right here visceral sensory information is going to go back up into the brain stem here let's see so if there is damage to our glossopharyngeal nerve this is going to produce reduced salivary secretion we still have two other glands being generated by the facial nerve though right so not we're not gonna have complete dry mouth but then loss of sensation and taste on the back of the tongue here all right vegas nerve here's a nice schematic of it coming out of the cranial vault got our superior and inferior ganglia associated with it it's going to send some fibers here right to the back of the throat and then it's going to send some fibers here to our larynx and then we're going to send some fibers here to the heart into the lungs and then to our abdominal viscera everything i'm outside of the pelvic organs right everything before of course that the descending colon there's not showing the transverse just because you wouldn't be able to see these other structures all right so somatic motor innervation most pharyngeal and laryngeal muscles in this area here pharyngeal muscles help you swallow laryngeal muscles are going to help you speak make sounds right our visceral motor to all of the structures in our thoracic and abdominal cavities and we are going to synapse on intrinsic ganglia in or near the viscera right so we can synapse for example in superior our cervical ganglia we can see here we see our aorta renal ganglia right here or we can go to the organs and there may be ganglia in the organs such as the intestines those will be inter intramural we're almost there we're going to finish up with cranial nerve 10 here with our somatic and visceral sensory we do have somatic sensory from the vegas nerve this is going to be our outside ear hole external acoustic meatus eardrum and pharynx okay so they're all going to be located in this area here visceral sensation we're going to have sensation from the pharynx larynx the carotid carotid body or the i'm sorry the carotid artery not the carotid body the carotid artery here and then they're going to synapse in the brain stem nuclei all right so information that is going to be carried in this location let me see real quick um what was i think i just want to double check yeah um information that if there is damage there we go we're going to have difficulty swallowing right not completely but we can get the first part going because the glossopharyngeal nerve is intact but if the vegas nerve we're going to we're going to impact the middle and inferior constrictor muscles those are going to be the ones that push the food down into your esophagus here and then also our larynx if we lose innervation to our larynx it's going to cause hoarseness in the monotone voice or complete loss that is because our what we think of our vocal voice box or our vocal folds in here right so vegas nerve difficulty swallowing um and then impaired gi system mobility which is a big issue right because it's going to innervate our gi system that needs to push things through via visceral motor and then hoarseness and monotone and complete or complete loss so vegas nerve does a lot i'm not really concerned about this today or for this block all right final two accessory and hypoglossal accessory is going to be very straightforward it's going to provide motor innervation to the sternocleidomastoid in the trapezius and hypoglossal is going to provide motor innervation to the tongue okay here's the lovely view here's our sternum here this is the anterior view of our spinal cord here i recall that um uh spinal accessory nerve is really um really a combination of um branches of spinal nerves coming up and making a nerve that goes in the foramen magnum and then out that jugular foramen kind of crazy right but it's pretty neat because you can see it going right to the sternocleidomastoid you can trace it going right into the trapezius so that i actually got to see today which is pretty darn neat all right so again pretty straightforward in terms of what it does just somatic motor sternocleidomastoid recall that once the sternocleidomastoid contracts is going to allow you to rotate the head contralateral to the muscle that's contracting so you're going to turn your head the opposite side and trapezius this is going to help you shrug your shoulders really in terms of this context and those are the actions that you ask individuals to do to test for um to test if this muscle is functioning um like i told you um we're going to enter we're going to re we're going to enter the cranial vault through the foramen magnum going up and then exit via that jugular foramen width cranial nerves nine and ten so nine ten and eleven again jugular we can see um cranial nerve um let's see nine it's just going to be cranial nerve uh excuse this is going to be your cranial nerve ten good gracious me okay conditions caused by damage well here you go paralysis to these muscles so difficulty elevating your shoulder shrugging or turning your head to the opposite side right because it's going to help you turn your head to the opposite side contralateral all right last one here hypoglossal is going to primarily do somatic information innovation to the tongue muscles so almost all the tongue muscles all the tongue muscles for really what we're getting at here right so somatic motor to all the tongue muscles we can see um the hypoglossal nerve it's going to come out more laterally um in the brain stem if if you uh it's more medially right so we can see that coming out kind of that that medial aspect of the brain stem here and we're going to send motor innervation out from our cranial nerve 12 nucleus it's going to come on down and we're going to send innervation to all these muscles here palatoglossus and our genioglossus and our hyoglossus and then it's also going to meet up with oh this is so cool i like this image because you can see anybody remember what this is it's a nice loop it's part of our peripheral nervous system this is going to be our answer cervicalis right so it's going to pretty much be combined and contribute to not contribute to but really meet up with our cervical plexus right so we can see our cervical plexus coming off here in the cervical vertebra contributing to muscles that are going to be our infra hyoid muscles right so don't confuse hypoglossal it's going to the tongue and just this one muscle it's going to be the thyrohyoid that we can see here all those other infra hyoid muscles are going to be via that cervical plexus and this is that answer cervicalis so if we have damage to this nerve we're going to have trouble swallowing our tongue does a lot of work in swallowing speaking and then also this is pretty pretty fun if you not fun for the individual but if you suspect a hypoglossal nerve paralysis or damage an individual asks the individual to stick out their tongue and the tongue will deviate or point to the side of the damage and that is because these muscles that are being damaged can't contribute to pointing the tongue straight so there's the tongue and it's going to deviate to the side of the damage and so just to kind of pull together all of our tongue stuff because there's a lot we're going to have all motor via our hypoglossal nerve anteriorly two-thirds we're going to have cranial nerve five doing somatic sensory and cranial oh that's not five cranial nerve five during somatic sensory cranial nerve seven facial during special sensory in the back here we're going to have just cranial nerve nine glossopharyngeal during some sensory um towards a somatic and special i like this drawing it helps me we have one more slide here and this is to review um those openings this will be on the exam right so here's our cribriform plate for the openings of cranial nerve one our optic nerve cranial nerve two is going to go through that optic canal cranial nerve three four v one so that's going to be the ophthalmic branch of five and six are going to go through the superior orbital fissure okay for raman rotundum that round one here is going to go anteriorly here oriented anteriorly our cranial nerve v two so that's going to be our maxillary branch of trigeminal for raman o valley is going to be right here right cranial nerve our mandibular branch of cranial nerve five is going to go through that going posteriorly here we have our internal auditory meatus or internal acoustic canal or any combination of those terms as long as it's internal we're going to have um seven and eight going into there and then we'll have our jagged jugular foramen nine ten and eleven um really are you can throw in our frame and magnum if you want for 11 and then 12 is going to go through an opening of its own name the hypoglossal canal there so this is information you got to know and pulling and it'll help you maybe pull it all together all right that's what i got we are going to reinforce several of these um concept when we do the eye and the ear and then we will also reinforce this during our learning activity for um on tuesday takes me a minute to get out of here sorry if you're still with me