cranial nerves 12/27 Flashcards
smell
CN 1
* close eyes, plug one nostril, smell olfactory stimulus placed under open nostril
+ inability to smell could indicate CN lesion, mucus, extreme old age, smoking history
Skip if deficit is not suspected
optic
CN 2
- Patient covers left eye and looks into examiners eye
- Ask patient to identify when examiner’s finger moves. Position finger approximately 2 feet lateral two and 6 inches above right eye, then flex finger. Repeat with finger position laterally and below, medially and above, and medially and below. Then test opposite eye.
Pupillary Light Reflex
CN 2,3
- Have patient look at distant object over examine her shoulder to prevent pupillary response to looking at a near object.
- Rapidly move flashlight to shine in one eye and then away. Normally both eyes will constrict equally.
- Repeat with opposite eye.
Upper eyelid position and raising upper eyelid
CN3, levator palpebrae
Ask patient to look straight ahead and observe space between upper back/lower eyelids (should be symmetrical). Ask patient to look up forward without moving head - upper eyelid should retract with upward gaze
Pupillary Responses
CN 2, 3
Observe pupils in room light - should be symmetric. CN3 lesion interferes with ipsilateral pupil, causing dilated pupil due to unopposed sympathetic input.
* Response to light
* Response to near\far- ask patient to look at distant object and then examiners nose. Pupil should dilate when looking at far object, constrict one looking at near object. CN III lesion will cause pupil to be dilated and remain unchanged.
Convergence
CN 3
Ask patient to look at tip of pen as it is slowly moved from approximately 2 feet away toward patient’s nose. Both eyes should remain directed until pen is within 10 cm of nose
Gaze Stability and Extraocular movements
CN 3, 4, 6
a. Forward gaze - both eyes should appear to look in the same direction, no nystagmus
Inspect eyes for asymmetry or ptosis
* Ipsilateral CN III lesion – one eye laterally and down
* Ipsilateral CN IV lesion – one eye looks upward
* Ipsilateral CN VI lesion – one eye looks medially
* Diplopia – present with any of the above
Ipsilateral CN III lesion
normal gaze - one eye laterally and down
w/wo diplopia
Ipsilateral CN IV lesion
normal gaze - one eye looks upward; Unable to depress eyes
w/wo diplopia
Ipsilateral CN VI lesion
normal gaze - one eye looks medially;
Unable to abduct eyes
w/wo diplopia
eye alignment
CN 3,4,6
ask patient look at distant object in central vision
* Cover Test (for trophia) – Cover left eye, and if right eye remains directed at target response is normal. If right eye moves, right eye is tropic. Repeat with opposite eye.
* Cover/Uncover test (for phoria) – cover one eye ~10seconds, then quickly uncover. Observe eye for any movement at instant eye is uncovered. Normal response is no movement. Movement indicates eye is phoric
smooth pursuit
CN 3,4,6
patient’s eyes follows examiners finger in H pattern
voluntary saccades
CN 3,4,6
hold index fingers ask to look back and forth between fingers
look at vertically striped cloth, move cloth horizontally
dynamic visual acuity
CN 3,4,6
maintain gaze on and read eye chart/image held stable 12-18 inches from the face as examiner/patient rotates patient’s head at 2Hz
requires intact VOR
nystagmus
CN 3,4,6
physiologic, pathologic, eye closed, eccentric gaze holding, BPPV
light touch/pin prick face
CN 5
close eyes, identify sharp or dull stimulus on face
corneal reflex
afferent CN5 (sensory), efferent CN7 (blink) touch cotton swab to cornea of eye
jaw clench
CN 5
patient clench jar, examiner push down on chin to try to separate
mandibular movement
CN 5
protrusion, retrusion, lateral deviation
facial expressions
CN 7
Raise eyebrows, close eyes tight, smile and show teeth, whistle and puff out cheeks
tongue taste
Sweet vs salty, bitter
CN7 facial - anterior tongue
CN9 glossopharyngeal - posterior 1/3
CN 10 vagus - back part of mouth
finger rub, watch ticking
CN 8
- lightly rub fingertips near both ears, should hear equally; if not progress to tuning fork tests
- hold watch far from ear and bring closer, record when first hears sound; + if unable to hear 18-24 inches or significant difference between sides
rinne test
CN 8
- hold vibrating 512 Hz tuning fork on mastoid process until no longer hears it
- move ~1cm in front of ear canal, should be able to hear it again
* sensorineural hearing loss, cochlear branch lesion - hears tuning fork through air after bone but reduced volume ipsilaterally
* conductive hearing loss - unable to hear outside of canal bc blockage in auditory canal or middle ear lesion
weber test
CN 8
- hold stem or tuning fork on top of head ask if sound is louder in one ear; should be same
* sensorineural, cochlear branch lesion - louder in unaffected ear, neural function impaired in affected ear
head impulse test
CN 8 VOR
look at examiners nose, head flexed 30deg
turn head passively and rapidly 2-3Hz small amplitude, abruptly stop in midline and observe eyes
- look for nystagmus or eye lag
gag reflex
CN 9, 10
touch soft palate w cotton swab or tongue depressor to elicit gag reflex
* normal: gag, symmetric elevation of palate
* abnormal: absent, asymmetric elevation- uvula deviates to stronger unaffected side
say “ahh”
CN 10
abnormal: voice hoarse, asymmetric elevation of soft palate - uvula deviates to stronger unaffected side
resisted shoulder shrug
CN 10, SCM and trap strength
- precaution for back or neck pain
- abnormal: unilateral paralysis or paresis
tongue protrusion
CN 12
tongue should protrude midline
* abnormal: deviates to weak side/side of lesion with ipsilateral atrophy
bell’s palsy indicates damage to what CN?
CN 7
drooping eyelid, inability to lift eyelid, dryness of eye
which CN provides autonomic innervation of abdominal viscera?
CN 10
anosmia is related to damage to which CN?
CN1, unable to detect smells
which CN originate in midbrain?
CN 3, 4
which CN originate in pons?
CN 5-8
which CN originate in medulla?
CN 9-12
what CN originates in frontal lobe?
CN 1, olfactory bulbs both sides of crista galli
what CN originates in temporal lobe?
CN 2 lateral colliculus
ability to swallow
CN 9, 10
what CN provides autonomic innervation to lacrimal glands?
CN 7
what CN provides autonomic innervation to submandibular and sublingual glands?
CN 7
2nd and 3rd largest salivary glands
what CN provides autonomic innervation to parotid gland?
CN 9
largest salivary gland
what CN is involved with voluntary mastication?
CN 5
what is the normal expected ratio of bone conduction to air conduction in Rinne test?
1:2 bone conduction vs air conduction
branches of trigeminal nerve CN5
ophthalmic, maxillary, and mandibular
exits at pons
how do you use a snellen chart
CN 2, patient stands 20 feet from the chart and proceeds to read the letters on the chart. The patient’s score is reported as 20 over the size of type the patient can read comfortably (e.g., 20/40).
which CN is involved with chewing
CN5
which CN is involved in sensation of anterior tongue
CN5
which CN is involved in taste of anterior tongue
CN7
which CN involved in swallowing
CN 9 and 10
bells palsy typically due to
inflammation, CN7 compressed
treat with corticosteroids, train muscles to strengthen
trigeminalgia
CN5 compressed, demyelinating
face hurts
