Okay, this is finally the video that I promised. This is the video on the functions of the cranial nerves. Before going forward keep in mind that this is a very basic review on the functions of the cranial nerves.
It is in no way exhaustive of other functions, but this video should give you a basic idea of what these cranial nerves actually do. So let's get started. Some of you have probably seen a picture similar to this to help people remember the functions of the cranial nerves.
This is going to be the one that I will be going over since it is also the picture that I used when I was a student. So let's start drawing this thing. With our blank space, let's start by drawing the number seven and then again backwards, let's draw the number seven again. This of course will be the outline of our face.
From here, I like to draw in the number one as the nose. Large 2s as the eyes and 3s for eyebrows. Next, I like to draw in small 4s at the medial corner of the 2s. and then a very large 5 which will give us part of the mouth and the forehead wrinkle. At this point I draw in 6 on both sides of the 2s.
We could skip 7 here since that is the first thing we did. So we could skip that and draw in 8s as our ears. Now this is where it could get a little tricky but just follow along and I will explain all of this later. So go ahead and draw in a large tongue and put in another 7 here but make sure the 7 takes up more than half of the front. of the tongue.
After that you could draw in a 9 and then a 10 right behind it. And why don't you give our man or woman a tongue ring? This is where we could draw in cranial nerve number 12. Finally we're left with cranial nerve 11. You could place them here where our person's shoulders are supposed to be. And that's it.
Okay so let's go over this. Cranial nerve 1 The olfactory nerve is purely a sensory nerve responsible for the sense of smell. That is why we had placed it as our person's nose. Cranial nerve 2, the optic nerve, is also purely a sensory nerve.
That is responsible for the sense of sight or vision. That is why it is our person's eyes. Cranial nerve 3, the oculomotor nerve, like its name says, is a motor nerve for the eyes and aids in eye movement. But keep in mind that there are other cranial nerves that are also responsible for eye movement, which I will talk about in more detail in another video.
But just for the sake of simplicity, just remember that cranial nerve 3 aids in the movement of our eyes. Also I like where we place our cranial nerve 3, because it helps us remember a few of the other things that cranial nerve 3 does. Because it is above our eyes on our drawing, this reminds us that cranial nerve 3 is the that one of the nerve's functions is in opening our eyelids.
And because of its proximity to our eyes, you could probably guess that this nerve has other functions associated with our eyes. These are a little more difficult to remember but include pupillary constriction and lens accommodation. Or in other words, it helps with focusing on things we see at different distances.
Remember that I said that there were other cranial nerves responsible for eye movement? Well, Let's talk about them now. These other nerves are cranial nerves 4, the trochlear nerve, and cranial nerves 6, abducens. Again, for simplicity's sake, just remember that these nerves are responsible for eye movement. And in summary, they are cranial nerves 3, the oculomotor nerve, cranial nerve 4, the trochlear nerve, and cranial nerve 6, abducens.
Cranial nerve 5, the trigeminal nerve, is our first sensory and motor nerve. And by looking at our drawing you could guess that it has something to do with the face. And of course you're right, cranial nerve 5 is responsible for facial sensation or what you feel on your face like pain or soft touch. You could also include the interior two-thirds of the tongue in this area that cranial nerve 5 innervates as its sensory component.
In regards to the motor component of cranial nerve 5 It innervates your muscles of mastication, and so it helps you open and close your jaw and aids in chewing your food. Cranial nerve 7, the facial nerve, is also a mixed sensory and motor nerve. Its motor component is responsible for facial expression and facial movement, so things like frowning and smiling are all due to cranial nerve 7. Its sensory component, on the other hand, is responsible for taste on the anterior two-thirds of the tongue. This is why we also have it located on the tongue on our drawing. However, don't confuse this with cranial nerve 5's involvement with somatosensation to the anterior two-thirds of the tongue, which is a different type of sense.
While we're here talking about the tongue, let's just go ahead and examine it further. Cranial nerve 9, the glossopharyngeal nerve, is both a sensory and motor nerve. Its sensory component is responsible for the sensation at the posterior one-third of the tongue.
This includes both taste and somatosensation. Note that cranial nerve 10 is also in this area, that's because it's involved in taste as well, but it's actually responsible for taste sensed at the epiglottis. Cranial nerve 10, because it's so far back in the throat on our drawing, also aids in swallowing but also has functions when we talk and cough.
Lastly on the tongue is cranial nerve 12. I placed it at the tip of our tongue because when a person sticks out their tongue, moves it side to side, you know that cranial nerve 12 is intact because it's responsible for tongue movement. Cranial nerve 8 is literally and figuratively our ears and it aids in hearing and balance. And finally cranial nerve 11 we had placed at our person's shoulders because it innervates your trapezius and sternocleidomastoid muscles Which helps with shrugging your shoulders and with turning your head I'm not a writer. Okay.