Cranial Nerve Examination Flashcards
1
Q
What equipment will you need before you start a cranial nerve exam?
A
● Pen torch
● Snellen chart
● Ishihara plates
● Ophthalmoscope and mydriatic eye drops (if necessary)
● Cotton wool
● Neuro-tip
● Tuning fork (512hz)
● Glass of water
2
Q
What position should the patient be in before commencing a cranial nerve exam?
A
● Ask the patient to sit on a chair, approximately one arm’s length away.
3
Q
Name some signs that may be present during a general inspection in a cranial nerve exam?
A
● Speech abnormalities
● Facial asymmetry
● Eyelid abnormalities
● Pupillary abnormalities
● Strabismus
● Limb associated signs
4
Q
Name some objects that may be present during a general inspection in a cranial nerve exam?
A
● Walking aids
● Hearing aids
● Visual aids
● Prescriptions
5
Q
What may speech abnormalities indicate when performing a general inspection during a cranial nerve exam?
A
● May indicate glossopharyngeal or vagus nerve pathology.
6
Q
What may facial asymmetry indicate when performing a general inspection during a cranial nerve exam?
A
● Suggestive of facial nerve palsy.
7
Q
What may eyelid abnormalities indicate when performing a general inspection during a cranial nerve exam?
A
● Ptosis may indicate oculomotor nerve pathology.
8
Q
What may pupillary abnormalities indicate when performing a general inspection during a cranial nerve exam?
A
● Mydriasis occurs in oculomotor nerve palsy.
9
Q
What may strabismus indicate when performing a general inspection during a cranial nerve exam?
A
● May indicate oculomotor, trochlear or abducens nerve palsy.
10
Q
What may limb associated signs may be observed when performing a general inspection during a cranial nerve exam?
A
● Pay attention to the patient’s arms and legs as they enter the room and take a seat noting any abnormalities (e.g. spasticity, weakness, wasting, tremor, fasciculation) which may suggest the presence of a neurological syndrome).
11
Q
What may walking aids indicate when performing a general inspection during a cranial nerve exam?
A
● Gait issues are associated with a wide range of neurological pathology including Parkinson’s disease, stroke, cerebellar disease and myasthenia gravis.
12
Q
What may hearing aids indicate when performing a general inspection during a cranial nerve exam?
A
● Often worn by patients with vestibulocochlear nerve issues (e.g. Ménière’s disease).
13
Q
What may visual aids indicate when performing a general inspection during a cranial nerve exam?
A
● The use of visual prisms or occluders may indicate underlying strabismus.
14
Q
What is the name of cranial nerve I?
A
● Olfactory nerve
15
Q
What is the sensory component of the olfactory nerve?
A
● The olfactory nerve (CN I) transmits sensory information about odours to the central nervous system where they are perceived as smell (olfaction).
16
Q
What is the motor component of the olfactory nerve?
A
● There is no motor component to the olfactory nerve.
17
Q
How would you assess cranial nerve I?
A
● Ask the patient if they have noticed any recent changes to their sense of smell.
● Olfaction can be tested more formally using different odours (e.g. lemon, peppermint), or most formally using the University of Pennsylvania smell identification test.
18
Q
List some causes of anosmia?
A
● Mucous blockage of the nose: preventing odours from reaching the olfactory nerve receptors.
● Head trauma: can result in shearing of the olfactory nerve fibres leading to anosmia.
● Genetics: some individuals have congenital anosmia.
● Parkinson’s disease: anosmia is an early feature of Parkinson’s disease.
● COVID-19: transient anosmia is a common feature of COVID-19.
19
Q
What is the name of cranial nerve II?
A
● Optic nerve
20
Q
What is the sensory component of optic nerve?
A
● The optic nerve (CN II) transmits sensory visual information from the retina to the brain.
21
Q
What is the motor component of the optic nerve?
A
● There is no motor component to the optic nerve.
22
Q
What aspects of the optic nerve should be assessed during a cranial nerve exam?
A
● Inspection of the pupils
● Visual acuity
● Pupillary reflexes
● Colour vision assessment
● Visual neglect / inattention
● Visual fields
● Blind spot
● Fundoscopy (most likely not required in OSCE but should mention it)
23
Q
What aspects of the pupils should be inspected during a cranial nerve exam?
A
● Assess pupil size
● Assess pupil shape
● Assess pupil symmetry
24
Q
What would a normal finding be when assessing pupil size during a cranial nerve exam?
A
● Normal pupil size varies between individuals and depends on lighting conditions (i.e. smaller in bright light, larger in the dark).
● Pupils are usually smaller in infancy and larger in adolescence.
25
What would a normal and abnormal finding be when assessing pupil shape during a cranial nerve exam?
● Pupils should be round, abnormal shapes can be congenital or due to pathology (e.g. posterior synechiae associated with uveitis).
● Peaked pupils in the context of trauma are suggestive of globe injury.
26
What would an abnormal finding be when assessing pupil symmetry during a cranial nerve exam?
● Examples of asymmetry include a large pupil in oculomotor nerve palsy and a small and reactive pupil in Horner’s syndrome.
27
What is the clinical name for asymmetry in pupil size?
● Anisocoria
28
Describe how you would perform assessment of visual acuity during a cranial nerve exam?
1. Stand the patient at 6 metres from the Snellen chart.
2. Ask the patient to cover one eye and read the lowest line they are able to.
3. Record the lowest line the patient was able to read (e.g. 6/6 (metric) which is equivalent to 20/20 (imperial)).
4. You can have the patient read through a pinhole to see if this improves vision (if vision is improved with a pinhole, it suggests there is a refractive component to the patient’s poor vision).
5. Repeat the above steps with the other eye.
29
What reflexes should be assessed when performing a pupillary reflex assessment during a cranial nerve exam?
● Direct pupillary reflex
● Consensual pupillary reflex
● Swinging light test
● Accommodation reflex
30
How would you assess the direct pupillary reflex during a cranial nerve exam, and what would a normal finding be?
● Shine the light from your pen torch into the patient’s pupil and observe for pupillary restriction in the ipsilateral eye.
● A normal direct pupillary reflex involves constriction of the pupil that the light is being shone into.
31
How would you assess the consensual pupillary reflex during a cranial nerve exam, and what would a normal finding be?
● Shine the light from your pen torch into the same pupil, but this time observe for pupillary restriction in the contralateral eye.
● A normal consensual pupillary reflex involves the contralateral pupil constricting as a response to light entering the eye being tested.
32
How would you perform the swinging light test during a cranial nerve exam?
● Move the pen torch rapidly between the two pupils to check for a relative afferent pupillary defect
33
What would a normal and abnormal finding be during the swinging light test?
● Normally, each illuminated pupil promptly becomes constricted. The opposite pupil also constricts consensually.
● The pupil, responding less vigorously, dilates from its prior constricted state when the light is moved away from the unaffected eye and towards the affected eye.
34
How would you assess the accommodation reflex during a cranial nerve exam?
1. Ask the patient to focus on a distant object (clock on the wall/light switch).
2. Place your finger approximately 20-30cm in front of their eyes (alternatively, use the patient’s own thumb).
3. Ask the patient to switch from looking at the distant object to the nearby finger/thumb.
4. Observe the pupils, you should see constriction and convergence bilaterally.
35
How would you assess colour vision during a cranial nerve exam?
1. Ask the patient to cover one of their eyes.
2. Then ask the patient to read the numbers on the Ishihara plates. The first page is usually the ‘test plate’ which does not test colour vision and instead assesses contrast sensitivity. If the patient is unable to read the test plate, you should document this.
3. If the patient is able to read the test plate, you should move through all of the Ishihara plates, asking the patient to identify the number on each. Once the test is complete, you should document the number of plates the patient identified correctly, including the test plate (e.g. 13/13).
4. Repeat the assessment on the other eye.
36
What are some causes of colour vision deficiencies?
● Colour vision deficiencies can be congenital or acquired. Some causes of acquired colour vision deficiency include:
● Optic neuritis: results in a reduction of colour vision (typically red).
● Vitamin A deficiency
● Chronic solvent exposure
37
How would you assess for visual neglect/inattention during a cranial nerve exam?
1. Position yourself sitting opposite the patient approximately 1 metre away.
2. Ask the patient to remain focused on a fixed point on your face (e.g. nose) and to state if they see your left, right or both hands moving.
3. Hold your hands out laterally with each occupying one side of the patient’s visual field (i.e. left and right).
4. Take turns wiggling a finger on each hand to see if the patient is able to correctly identify which hand has moved.
5. Finally wiggle both fingers simultaneously to see if the patient is able to correctly identify this (often patients with visual neglect will only report the hand moving in the unaffected visual field – i.e. ipsilateral to the primary brain lesion).
38
What is important to remember about abnormal findings when assessing for visual neglect/inattention during a cranial nerve exam?
● It should be noted that visual neglect is not caused by optic nerve pathology and therefore this test is often not included in a cranial nerve exam.
39
How should you position yourself when assessing the visual field during a cranial nerve exam?
● You need to position yourself, the patient and the target correctly as the assessment replies on you comparing the patient’s visual field with your own.
● You need to have normal visual fields and a normal-sized blind spot.
40
Describe how you would perform a visual field assessment during a cranial nerve exam?
1. Sit directly opposite the patient, at a distance of around 1 metre.
2. Ask the patient to cover one eye with their hand.
3. If the patient covers their right eye, you should cover your left eye (mirroring the patient).
4. Ask the patient to focus on part of your face (e.g. nose) and not move their head or eyes during the assessment. You should do the same and focus your gaze on the patient’s face.
5. As a screen for central visual field loss or distortion, ask the patient if any part of your face is missing or distorted. A formal assessment can be completed with an Amsler chart.
6. Position the hatpin (or another visual target such as your finger) at an equal distance between you and the patient (this is essential for the assessment to work).
7. Assess the patient’s peripheral visual field by comparing to your own and using the target. Start from the periphery and slowly move the target towards the centre, asking the patient to report when they first see it. If you are able to see the target but the patient cannot, this would suggest the patient has a reduced visual field.
8. Repeat this process for each visual field quadrant, then repeat the entire process for the other eye.
41
Name some types of visual field defects?
● Bitemporal hemianopia
● Homonymous field defects
● Scotoma
● Monocular vision loss
42
What is bitemporal hemianopia and what would it be suggestive of?
● Loss of the temporal visual field in both eyes resulting in central tunnel vision. Bitemporal hemianopia typically occurs as a result of optic chiasm compression by a tumour (e.g. pituitary adenoma, craniopharyngioma).
43
What is a homonymous field defect and what would it be suggestive of?
● Affect the same side of the visual field in each eye and are commonly attributed to stroke, tumour, abscess (i.e. pathology affecting visual pathways posterior to the optic chiasm).
● These are deemed hemianopias if half the vision is affected and quadrantanopias if a quarter of the vision is affected.
44
What is scotoma and what would it be suggestive of?
● An area of absent or reduced vision surrounded by areas of normal vision. There is a wide range of possible aetiologies including demyelinating disease (e.g. multiple sclerosis) and diabetic maculopathy.
45
What is monocular vision loss and what would it be suggestive of?
● Total loss of vision in one eye secondary to optic nerve pathology (e.g. anterior ischaemic optic neuropathy) or ocular diseases (e.g. central retinal artery occlusion, total retinal detachment).
46
What is a blind spot in the visual field and what causes it?
● A physiological blind spot exists in all healthy individuals as a result of the lack of photoreceptor cells in the area where the optic nerve passes through the optic disc.
● In day to day life, the brain does an excellent job of reducing our awareness of the blind spot by using information from other areas of the retina and the other eye to mask the defect.
47
Describe how you would perform a blind spot assessment during a cranial nerve exam?
Do end -poitnt review tomorrow
48
What is the final thing that should be offered to be performed when assessing the optic nerve?
● In the context of a cranial nerve examination, fundoscopy is performed to assess the optic disc for signs of pathology (e.g. papilloedema).
● You should offer to perform fundoscopy in your OSCE, however, it may not be required.
49
What is the name of cranial nerve III?
● The oculomotor nerve
50
What is the name of cranial nerve IV?
● The trochlear nerve
51
What is the name of cranial nerve VI?
● The abducens nerve
52
What is the motor component of the oculomotor, trochlear, and abducens nerve?
● The oculomotor (CN III), trochlear (CN IV) and abducens (CN VI) nerves transmit motor information to the extraocular muscles to control eye movement and eyelid function.
53
What is the function of the parasympathetic innervation of the oculomotor nerve?
● The oculomotor nerve also carries parasympathetic fibres responsible for pupillary constriction.
54
How would you generally assess the oculomotor, trochlear, and abducens nerve in a cranial nerve exam?
● Inspect the eyelids for evidence of ptosis.
55
What can ptosis be associated with in terms of cranial nerve pathologies?
● Oculomotor nerve pathology
● Horner’s syndrome
● Neuromuscular pathology (e.g. myasthenia gravis)
56
How would you formally assess the oculomotor, trochlear, and abducens nerve in a cranial nerve exam?
1. Hold your finger (or a pin) approximately 30cm in front of the patient’s eyes and ask them to focus on it. Look at the eyes in the primary position for any deviation or abnormal movements.
2. Ask the patient to keep their head still whilst following your finger with their eyes. Ask them to let you know if they experience any double vision or pain.
3. Move your finger through the various axes of eye movement in a ‘H’ pattern.
4. Observe for any restriction of eye movement and note any nystagmus (which may suggest vestibular nerve pathology or stroke).
57
What is the action of the superior rectus muscle?
● Primary action is elevation ● Secondary actions include adduction and medial rotation of the eyeball.
58
What is the action of the inferior rectus muscle?
● Primary action is depression,
● Secondary actions include adduction and lateral rotation of the eyeball.
59
What is the action of the medial rectus muscle?
● Adduction of the eyeball.
60
What is the action of the lateral rectus muscle?
● Abduction of the eyeball.
61
What is the action of the superior oblique muscle?
● Depresses, abducts and medially rotates the eyeball.
62
What is the action of the inferior oblique muscle?
● Elevates, abducts and laterally rotates the eyeball.
63
What muscles of the eye does the oculomotor nerve innervate?
● The oculomotor nerve supplies all extraocular muscles except the superior oblique and the lateral rectus.
64
What would be observed in a patient with oculomotor palsy?
● Results in the unopposed action of both the lateral rectus and superior oblique muscles, which pull the eye inferolaterally.
● As a result, patients typically present with a ‘down and out’ appearance of the affected eye.
65
What muscles of the eye does the trochlear nerve innervate?
● The only muscle the trochlear nerve innervates is the superior oblique muscle.
66
What would be observed in a patient with trochlear nerve palsy?
● Typically results in vertical diplopia when looking inferiorly, due to loss of the superior oblique’s action of pulling the eye downwards.
● Patients often try to compensate for this by tilting their head forwards and tucking their chin in, which minimises vertical diplopia.
● Trochlear nerve palsy also causes torsional diplopia (as the superior oblique muscle assists with intorsion of the eye as the head tilts).
● To compensate for this, patients with trochlear nerve palsy tilt their head to the opposite side, in order to fuse the two images together.
67
What muscles of the eye does the abducens nerve innervate?
● The abducens nerve (CN VI) innervates the lateral rectus muscle.
68
What would be observed in a patient with abducens nerve palsy?
● Results in unopposed adduction of the eye (by the medial rectus muscle), resulting in a convergent squint.
● Patients typically present with horizontal diplopia which is worsened when they attempt to look towards the affected side.
69
What is strabismus?
● Strabismus is a condition in which the eyes do not properly align with each other when looking at an object. Pathology affecting the oculomotor, trochlear or abducens nerves can cause strabismus.
70
How would you assess strabismus in a cranial nerve exam using the light reflex test?
1. Ask the patient to focus on a target approximately half a metre away whilst you shine a pen torch towards both eyes.
2. Inspect the corneal reflex on each eye:
● If the ocular alignment is normal, the light reflex will be positioned centrally and symmetrically in each pupil.
● Deflection of the corneal light reflex in one eye suggests a misalignment.
71
How would assess strabismus in a cranial nerve exam using the cover test?
1. Ask the patient to fixate on a target (e.g. light switch).
2. Occlude one of the patient’s eyes and observe the contralateral eye for a shift in fixation:
● If there is no shift in fixation in the contralateral eye, while covering either eye, the patient is orthotropic (i.e. normal alignment).
● If there is a shift in fixation in the contralateral eye, while covering the other eye, the patient has a heterotropia.
3. Repeat the cover test on the other eye.
72
What is the name of cranial nerve V?
● Trigeminal nerve (CN V)
73
What are the three subdivisions of the trigeminal nerve?
● Ophthalmic (V1)
● Maxillary (V2)
● Mandibular (V3)
74
What is the sensory component of the opthalmic (V1) branch of the trigeminal nerve?
● Carries sensory information from the scalp and forehead, nose, upper eyelid as well as the conjunctiva and cornea of the eye.
75
What is the sensory component of the maxillary (V2) branch of the trigeminal nerve?
● Carries sensory information from the lower eyelid, cheek, nares, upper lip, upper teeth and gums.
76
What is the sensory component of the mandibular (V3) branch of the trigeminal nerve?
● Carries sensory information from the chin, jaw, lower lip, mouth, lower teeth and gums.
77
What is the motor component of the trigeminal nerve?
● Only the mandibular (V3) branch carries a motor component.
● Carries motor information to the muscles of mastication as well as the tensor tympani, tensor veli palatini, mylohyoid and digastric muscles.
78
Describe how would you assess the sensory component of the trigeminal nerve during a cranial nerve exam?
1. First, explain the modalities of sensation you are going to assess (e.g. light touch/pinprick) to the patient by demonstrating on their sternum.
2. Ask the patient to close their eyes and say ‘yes’ each time they feel you touch their face.
3. Assess the sensory component of V1, V2 and V3 by testing light touch and pinprick sensation across regions of the face supplied by each branch:
● Forehead (lateral aspect): ophthalmic (V1)
● Cheek: maxillary (V2)
● Lower jaw (avoid the angle of the mandible as it is supplied by C2/C3): mandibular branch (V3)
4. You should compare each region on both sides of the face to allow the patient to identify subtle differences in sensation.
79
Describe how you would assess the motor component of the trigeminal nerve during a cranial nerve exam?
1. Inspect the temporalis (located in the temple region) and masseter muscles (located at the posterior jaw) for evidence of wasting. This is typically most noticeable in the temporalis muscles, where a hollowing effect in the temple region is observed.
2. Palpate the masseter muscle (located at the posterior jaw) bilaterally whilst asking the patient to clench their teeth to allow you to assess and compare muscle bulk.
3. Ask the patient to open their mouth whilst you apply resistance underneath the jaw to assess the lateral pterygoid muscles. An inability to open the jaw against resistance or deviation of the jaw (typically to the side of the lesion) may occur in trigeminal nerve palsy.
80
What two reflexes can be used to assess the trigeminal nerve during a cranial nerve exam?
● Jaw Jerk Reflex
● Corneal reflex
81
Describe how you would assess the jaw jerk reflex when performing a trigeminal nerve assessment in a cranial nerve exam?
1. Clearly explain what the procedure will involve to the patient and gain consent to proceed.
2. Ask the patient to open their mouth.
3. Place your finger horizontally across the patient’s chin.
4. Tap your finger gently with the tendon hammer.
5. In healthy individuals, this should trigger a slight closure of the mouth. In patients with upper motor neuron lesions, the jaw may briskly move upwards causing the mouth to close completely.
82
Describe how you would assess the corneal reflex when performing a trigeminal nerve assessment in a cranial nerve exam?
1. Clearly explain what the procedure will involve to the patient and gain consent to proceed.
2. Gently touch the edge of the cornea using a wisp of cotton wool.
3. In healthy individuals, you should observe both direct and consensual blinking. The absence of a blinking response suggests pathology involving either the trigeminal or facial nerve.
*This is not usually required in an OSCE; however, you should offer to test it.
83
What is the name of cranial nerve VII?
● The facial nerve
84
What is the motor component of the facial nerve?
● Transmits motor information to the muscles of facial expression and the stapedius muscle (involved in the regulation of hearing).
85
What is the sensory component of the facial nerve?
● The facial nerve has a sensory component responsible for the conveyance of taste from the anterior two-thirds of the tongue.
86
How would you assess the sensory component of the facial nerve in a cranial nerve exam?
● Ask the patient if they have noticed any recent changes in their sense of taste.
87
What topics should be covered when assessing the motor component of the facial nerve in a cranial nerve exam?
● Hearing changes
● Inspection of the face
● Facial movement assessment
88
How would you assess hearing changes in relation to the motor component of the facial nerve in a cranial nerve exam?
● Ask the patient if they have noticed any changes to their hearing (paralysis of the stapedius muscle can result in hyperacusis).
89
What aspects of the patients face should be inspected when assessing the motor component of the facial nerve in a cranial nerve exam?
● Inspect the patient’s face at rest for asymmetry, paying particular attention to:
● Forehead wrinkles
● Nasolabial folds
● Angles of the mouth
90
What facial expressions should you ask the patient to perform when assessing the motor component of the facial nerve in a cranial nerve exam?
● Raise eyebrows
● Scrunch the eyes
● Blow out your cheeks
● Smiling
● Pursed lips
91
What is the name of cranial nerve VIII?
● The vestibulocochlear nerve
92
What is the sensory component of the vestibulocochlear nerve?
● Transmits sensory information about sound and balance from the inner ear to the brain.
● NOTE. The vestibulocochlear nerve has no motor component.
93
How would you perform a gross hearing assessment when assessing the vestibulocochlear nerve in a cranial nerve exam?
1. Position yourself approximately 60cm from the ear and then whisper a number or word.
2. Mask the ear not being tested by rubbing the tragus. Do not place your arm across the face of the patient when rubbing the tragus, it is far nicer to occlude the ear from behind the head. If possible shield the patient’s eyes to prevent any visual stimulus.
3. Ask the patient to repeat the number or word back to you. If they get two-thirds or more correct then their hearing level is 12db or better. If there is no response use a conversational voice (48db or worse) or loud voice (76db or worse).
4. If there is no response you can move closer and repeat the test at 15cm. Here the thresholds are 34db for a whisper and 56db for a conversational voice.
5. Assess the other ear in the same way.
94
Describe how you would perform Rinne's test for assessment of the vestibulocochlear nerve in a cranial nerve exam?
1. Place a vibrating 512 Hz tuning fork firmly on the mastoid process (apply pressure to the opposite side of the head to make sure the contact is firm). This tests bone conduction.
2. Confirm the patient can hear the sound of the tuning fork and then ask them to tell you when they can no longer hear it.
3. When the patient can no longer hear the sound, move the tuning fork in front of the external auditory meatus to test air conduction.
4. Ask the patient if they can now hear the sound again. If they can hear the sound, it suggests air conduction is better than bone conduction, which is what would be expected in a healthy individual (this is often confusingly referred to as a “Rinne’s positive” result).
95
What is a normal finding be in Rinne's test?
● Normal result: air conduction > bone conduction (Rinne’s positive)
96
What would the Rinne's test result be in a patient with sensorineural deafness?
● Air conduction > bone conduction (Rinne’s positive) – due to both air and bone conduction being reduced equally
97
What would the Rinne's test result be in a patient with conductive deafness?
● Bone conduction > air conduction (Rinne’s negative)
98
Describe how you would perform Weber's test for assessment of the vestibulocochlear nerve in a cranial nerve exam?
1. Tap a 512Hz tuning fork and place in the midline of the forehead. The tuning fork should be set in motion by striking it on your knee (not the patient’s knee or a table).
2. Ask the patient “Where do you hear the sound?”
● These results should be assessed in context with the results of Rinne’s test before any diagnostic assumptions are made:
99
What would a normal finding be in Weber's test?
● Normal: sound is heard equally in both ears.
100
What would the Weber's test result be in a patient with sensorineural deafness?
● Sound is heard louder on the side of the intact ear.
101
What would the Weber's test result be in a patient with conductive deafness?
● Sound is heard louder on the side of the affected ear.
102
What Hz tuning fork would be used when performing Rinne's and Weber's test in a cranial nerve exam?
● 512 Hz
103
What is conductive hearing loss?
● Conductive hearing loss occurs when sound is unable to effectively transfer at any point between the outer ear, external auditory canal, tympanic membrane and middle ear (ossicles).
104
List some causes of conductive hearing loss?
● Causes of conductive hearing loss include excessive ear wax, otitis externa, otitis media, perforated tympanic membrane and otosclerosis.
105
What is sensorineural hearing loss?
● Sensorineural hearing loss occurs due to dysfunction of the cochlea and/or vestibulocochlear nerve.
106
List some causes of sensorineural hearing loss?
● Causes of sensorineural hearing loss include increasing age (presbycusis), excessive noise exposure, genetic mutations, viral infections (e.g. cytomegalovirus) and ototoxic agents (e.g. gentamicin).
107
What is the name of cranial nerve IX?
● Glossopharyngeal nerve
108
What is the name of cranial nerve X?
● Vagus nerve
109
What is the motor component of the glossopharyngeal nerve?
● The glossopharyngeal nerve transmits motor information to the stylopharyngeus muscle which elevates the pharynx during swallowing and speech.
110
What is the sensory component of the glossopharyngeal nerve?
● The glossopharyngeal nerve also transmits sensory information that conveys taste from the posterior third of the tongue.
111
What is the motor component of the vagus nerve?
● The vagus nerve transmits motor information to several muscles of the mouth which are involved in the production of speech
112
How would you inspect the glossopharyngeal and vagus nerve in a cranial nerve exam?
● Ask the patient to open their mouth and inspect the soft palate and uvula
● Ask the patient to say “ahh“
● Ask the patient to cough
● Perform a swallow assessment
● Test the gag reflex of a patient
113
What should you note about the uvula when assessing the glossopharyngeal and vagus nerve in a cranial nerve exam?
● Note the position of the uvula.
● Vagus nerve lesions result in deviation of the uvula towards the unaffected side.
114
What should you inspect when asking the patient to say 'ahh' when assessing the glossopharyngeal and vagus nerve in a cranial nerve exam?
● Inspect the palate and uvula which should elevate symmetrically, with the uvula remaining in the midline.
● A vagus nerve lesion will cause asymmetrical elevation of the palate and uvula deviation away from the lesion.
115
What should you assess when asking the patient to cough when assessing the glossopharyngeal and vagus nerve in a cranial nerve exam?
● Vagus nerve lesions can result in the presence of a weak, non-explosive sounding bovine cough caused by an inability to close the glottis.
116
Describe how you would perform a swallow assessment for the glossopharyngeal and vagus nerve in a cranial nerve exam?
● Ask the patient to take a small sip of water (approximately 3 teaspoons) and observe the patient swallow.
● The presence of a cough or a change to the quality of their voice suggests an ineffective swallow which can be caused by both glossopharyngeal (afferent) and vagus (efferent) nerve pathology.
117
Describe how the gag reflex works in terms of innervation by the glossopharyngeal and vagus nerve
● The gag reflex involves both the glossopharyngeal nerve (afferent) and the vagus nerve (efferent).
118
Describe how you would perform a gag reflex test when assessing the glossopharyngeal and vagus nerve in a cranial nerve exam?
1. Stimulate the posterior aspect of the tongue and oropharynx which in healthy individuals should trigger a gag reflex.
● The absence of a gag reflex can be caused by both glossopharyngeal and vagus nerve pathology.
● You should NOT perform this test in an OSCE, although you may be expected to have an understanding of what cranial nerves are involved in the reflex.
119
What is the name of cranial nerve XI?
● The accessory nerve
120
What is the motor component of the accessory nerve?
● Transmits motor information to the sternocleidomastoid and trapezius muscles.
● NOTE. It does not have a sensory component.
121
Describe how you would assess the accessory nerve in a cranial nerve exam?
1. First, inspect for evidence sternocleidomastoid or trapezius muscle wasting.
2. Ask the patient to raise their shoulders and resist you pushing them downwards: this assesses the trapezius muscle (accessory nerve palsy will result in weakness).
3. Ask the patient to turn their head left whilst you resist the movement and then repeat with the patient turning their head to the right: this assesses the sternocleidomastoid muscle (accessory nerve palsy will result in weakness).
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What is the name of cranial nerve XII?
● The hypoglossal nerve
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What is the motor component of the hypoglossal nerve?
● Transmits motor information to the extrinsic muscles of the tongue (except for palatoglossus which is innervated by the vagus nerve).
● NOTE. It does not have a sensory component.
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Describe how you would assess the hypoglossal nerve in a cranial nerve exam?
1. Ask the patient to open their mouth and inspect the tongue for wasting and fasciculations at rest (minor fasciculations can be normal).
2. Ask the patient to protrude their tongue and observe for any deviation (which occurs towards the side of a hypoglossal lesion).
3. Place your finger on the patient’s cheek and ask them to push their tongue against it. Repeat this on each cheek to assess and compare power (weakness would be present on the side of the lesion).
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What further assessments and investigations can be performed after a cranial nerve exam?
● Full neurological examination including the upper and lower limbs.
● Neuroimaging (e.g. MRI head): if there are concerns about space-occupying lesions or demyelination.
● Formal hearing assessment (including pure tone audiometry): if there are concerns about vestibulocochlear nerve function.
