Devise a series of physical examination tests that assess the function of each of the cranial nerves.

Video transcript

Hi, everyone. Our next question says, the corneal reflex tests, which cranial nerve or nerves, a cranial nerve, one B, cranial nerve, three, C cranial nerve five or D. Cranial nerve seven. Then there's E A and B or FC and D. So as our question says, we have the potential of either one or two nerves. So let's recall what the corneal reflex is. And that's essentially the eye blink reflex. So when something comes in contact with the cornea, the eyelids flink shut. So this is actually a pathway that needs two different nerves. You have the sensory information of something coming into contact with the epithelium of the cornea. And then you have the motor message to cause the eye to blink shut. So that goes to the orbicularis oculi muscles surrounding the eyelids. And these two pathways are on two different nerves. So, testing the corneal reflex would let you know there's a problem with either one of those. So the sensory information that there's something has come in contact with cornea is carried by cranial nerve five, which is the trigeminal nerve and the motor message. So, causing the eye to blink is carried by a cranial nerve seven or the facial nerve. So we will be looking at E or F since we have two different nerves. So let's locate our correct answer here. So we have cranial nerve five as choice C A little dot there and cranial nerve seven is choice D. So our answer is going to be choice FC and D. So we're gonna look at our other answer. Choices. Choice B. Cranial nerve three might be one we're tempted to pick because cranial nerve three is the ocular motor nerve. So we're thinking about motor movements of the eye, but it's mainly giving motor messages to move the eyeball itself. So not responsible for the blink, although it also does control the movement of the upper eyelid, but it is not what enervates the orbicularis oculi muscles, which are what actually blinks the eyes shut. So that one's a little bit tricky but choice B is not correct in this case. And a choice, a cranial nerve one that's a little easier to rule out. This is the olfactory nerve. So responsible for receiving information about smells, so definitely incorrect. And that also, of course rules out choice E A and B. So once again, the corneal reflex texts which cranial nerves, choice FC and D. Cranial nerve five and cranial nerve seven. See you in the next video.