Cranial Nerve V: The Trigeminal Nerve – Your Ultimate Guide To Cranial Nerve Examination - Dr Gill

[Music] okay we're getting there now so we've covered cranial nerves 1 2 3 4 & 6 but we've missed 5 with miss 5 because it falls out of order so it makes sense to stay with all the muscles involved with the eye so so we've done cranial nerve one two three four and six but we've missed out five now I think it makes sense to examine two two six all together because they're all focused very much with the eye we do appreciate that there's a small amount of motor involvement from cranial enough 3 being able to constrict the pupil but cranial nerve 5 stands on its own away from the eye in many ways [Music] so cranial nerve 5 is mainly a sensory nerve having sensation across the face but there is also a small motor component affecting the muscles that we chew with the muscles of mastication in terms of the muscles of mastication the trigeminal nerve innervates the temporalis the masseter and inside the pterygoid muscles which are involved in moving the jaw side-to-side which is why when testing it we get the patient to bite down once bite down twice and then wiggle their jaw side-to-side but in terms of assessing we need to have a blunt object and some cotton wool and what we're going to do is we twizzle it to get a point we'll get the patient to close their eyes as we check their sensation so they're not given any extra clues by seeing us approach them and then we use that point of cotton wall to assess the three regions where the trigeminal nerve provides sensation to the face the sensory branches of the trigeminal nerve are considered to be v1 v2 and v3 more easily described these are the ophthalmic region the maxillary region and the mandibular region crucially for this we don't stroke the patient it's just a simple touch and down touch and down touch and gone and the same is true for when we use our sharp object when testing the neuro tip it's important to demonstrate on the patient's finger what it feels like so there's no worry in the patients mind when you're doing the examination and the same is true for when we use our sharp object or neuro tip it's a light touch we're not causing any pain or discomfort to the patient as we do so [Music] now we're going to look at your sense of sensation on your face so I've got a little point here but it is blunt and if I could have a finger okay so you can see you can feel it but it isn't sharp okay if you close your eyes and tell my new feet later yep yep yep yep yep yep in terms of checking the corneal reflex which is part of trigeminal v examination obviously it is the Krenim of v that is transmitting the sensation from the cornea and it is the oculomotor nerve which is allowing the blink we're going to take the twizzle cotton and come in to the side just touching over the cornea we don't want to come in from the front because the patient will see us and will likely blink anyway we may find that ladies and chaps who wear contact lenses actually lose their corneal reflex because they're used to having something on their eyes anyway [Music] okay and now we're going to see what's the sensation on your eyes alike again so I've got a bit of cotton wool and if you could look all the way to the outside for me and I'm just going to bring this in from the side I'm just going to touch the side of your eye that's fine we get to the same if you could look over that way you seem to come in from the side and then just up Jim okay super thank you very much sometimes a Georgia oak is tested where we get the patient to relax and then strike the tendon hammer over the bottom of their face in most patients we should not expect to find the mouth closing in response to that reflux finally if you could try and relax your jaw for me I'm just going to tap over your jaw one of the commonest causes of a problem with cranial nerve five which you can see here this large nerve is a tumor coming from cranial nerve eight and you can see how close they are bizarrely a crane enough five lesion one of the first things to show up may actually be a hearing loss due to an acoustic neuroma affecting the ear which is then leading to press on cranial nerve five heads highlighting why all the cranial nerve should be tested together this acoustic neuroma is one of the few areas that may give rise to the loss of the georgia reflex early on as a presentation cranial nerve eight Toomas acoustic neuromas and the like account for 5% of all tumors and grow in this region hence the greater likelihood of significant pressure going on cranial nerve of five finally to complete the trigeminal nerve examination some examiner's will perform a glabella tap tapping on the forehead should elicit a blink response from the patient whilst the glabella tap reflex can be overcome by multiple tapping of the forehead it is seen to be absent in patients that have a frontal release issues and is sometimes seen in patients who have Parkinson's disease ie you tap the forehead and there is no response this glabella tap reflex shows how interconnected craning of five and cranial nerve seven the facial nerve are the glabella reflex relies on both cranial nerve five and cranial nerve seven as cranial nerve five provides the afferent fibers ie the sensation fibers and it is cranial nerve seven this is providing the afferent or exit fibers [Music] now I'd like to tap on your forehead just relax for me okay so we've got a nice blink man that's good [Music]