CN
I
Name
Olfactory
Function
Smell
Screening Process
Ask pt to breath in through nose as PT occludes one nostril at a time.
Ask pt to close eyes.
Occlude 1 nostril, & introduce a familiar & friendly scent. Ask pt to
smell & report what the smell is.
Ask pt to compare strength of smell in each nostril.
Causes of damage
-Head trauma (tearing of olfactory
afferents as pass through cribiform
plate, or of olfactory tract itself)
-Compression of olfactory bulb &/or
tract (meningioma of frontal lobe)
-Degenerative diseases (Parkinson’s,
Alzheimers)
-Toxic inhalation
-Common cold (temporarily loss)
Consequences of damage
Anosmia (inability to smell)
II
Optic
Vision
Visual acuity:
Use Snellen chart 20’ or handheld chart 1’ away.
Ask pt to cover 1 eye & read lowest line possible.
Repeat for other eye.
Test w/ glasses/contacts if normally used 4 fxn.
-Optic neuritis (inflammation of the
optic nerve, often due to MS)
-Central scotoma: visual loss in the center of the field, decreased
visual acuity, impaired color vision
-Papilledema (optic disc swelling
due to elevated intracranial
pressure)
-Enlargement of the blind spot
-Prechiasmal lesions (i.e. to the optic
nerve)
-Scotomas
-Monocular field defect:
-lesion to the optic nerve (distal to the chiasm)
-Hemianopsia: loss of ½ of the visual field
-lesion to the optic tract (proximal to the chiasm)
-if lesion to R tract, lose entire L visual field (R retinal field loss)
-Damage at the chiasm (often due to
pressure from a tumor of the
pituitary gland)
-visual field defects in BOTH eyes
-medial chiasm damage: bitemporal hemianopsia
-lateral chiasm damage: nasal hemianopsia
Visual fields:
Face pt 1’ away, at eye level.
Instruct pt to cover 1 eye. PT covers mirrored eye.
Instruct pt to look you in the eye & say “now” when they see your
finger appear from out of sight.
Extend your arm & 1st 2 fingers out of sight at a diagonal, then slowly
bring centrally, noticing when fingers enter your field of vision.
Pt should say “now” at same time you see your fingers.
Repeat for all 4 quadrants.
PLR: Parasympathetic:
CN II: afferent
CN III: efferent
III,
Oculomotor
Pupillary light reflex:
Check penlight in your hand for loose parts.
Ask pt to put hand up along axis of nose.
Slowly bring penlight in towards pt’s eye.
Repeat for other eye.
Should see bilateral pupil constriction.
Ipsilateral response is “direct response”.
Contralateral response is “consensual response”.
-Motor to: SR, LPS, MR,
IR, IO
-Parasympathetic
efferent limb of PLR
Smooth pursuit:
Instruct pt to follow fingers w/ their eyes w/o moving head.
Move fingers slowly at eye level horizontally, vertically, in an “H”
pattern
Saccades:
Hold fingers 4-6” apart and 18” from pt’s face.
Instruct pt to look back & forth between the 2 as quickly as possible.
IV,
Trochlear
-Motor to SO (up & R/L)
VI
Abducens
-Motor to LR (R/L)
-Diabetes
Palsy (paralysis)
Meningeal inflammation
Aneurysm to upper basilar artery
Sinus infection / thrombosis
Aniscoria (pupillary inequality): If R optic nerve damage, neither
direct nor consensual pupillary response is seen with light shone
in R eye. Light shone in L eye, direct & consensual responses both
seen.
Opthalmoplegia: paralysis of 1 or more extraocular muscles
Strabismus: inability to direct both eyes to same object so that the
visual axes of the 2 eyes are misaligned
-Results in diplopia
Diplopia is the single symptom of opthalmoplegia. Double vision
due to image of 1 eye falling on a different spot on the retina than
Do horizontally, vertically, & diagonally.
-All 3 together =
“conjugate movement”
V
Trigeminal
V3
Facial sensation;
sensation from cornea
(V1- corneal reflex- CN
VII is efferent limb)
Motor to muscles of
mastication, mylohyoid,
digastric, tensor veli
palatine, tensor tympani
(efferent limb of
auditory/stapedius
reflex)
Convergence/Divergence:
Instruct pt to hold thumb out & focus on it, then bring it close to face
then back out. Ask pt to tell you when there are 2 images
(convergence, 2”) & when it’s single again (divergence, 4-6”).
About 2” from the nose there is usually double vision or eyestrain
that should clear up as pt brings thumb back out. Look for eyes
moving medially as thumb gets closer.
Sharp and Dull:
Test as would on body, with q-tip & pin).
Instruct pt to close their eyes & tell you when they feel you touch
their face. Randomly touch pt’s face above each temple, next to the
nose, & on each side of the chin. Ask pt to compare strength of
sensation & whether feels dull or sharp.
Resisted jaw closure: Palpate masseter & temporal muscles while
instruct patient to bite down hard while you apply downward
pressure to chin trying to open mouth.
III: aneurysm to PCA, tumor,
extradural hematoma
VI: rise in intracranial pressure
the other eye
CN III: Ptosis: eyelid droop due to weakness of levator palpebrae
superioris. Lateral strabismus due to MR paralysis. No pupillary
light reflex.
CN IV: Extortion (outward rotation) due to paralysis of SO
CN VI: Medial strabismus due to LR paralysis
-Wallenberg’s Syndrome
(occlusion of PICA in lower medulla)
-Loss of pain/thermal sense in IL face & CL body
-Tumor in middle fossa of cranium
-Problems with jaw movement
-Hyper-acoustic (sensitivity to loud sounds)
-LMN damage: muscle atrophy, low tone, dysarthria
-UMN damage: problems with chewing & speech; spastic
dysarthria; tight and spastic speech
-Corticobulbar lesion
-Trigeminal neuralgia (no motor or
sensory deficits, only pain)
Bursts of pain to 1 of the 3 sensory areas
Resisted jaw opening: Ask pt to open their mouth as you apply
resistance to underneath of pt’s chin. Allow mouth to open slowly.
Corneal reflex (wisp of cotton). Afferent = V1; efferent is VII.
VII
Facial
-Motor to muscles of
facial expression,
stapedius, stylohyoid,
digastric
Ask pt to perform the following facial expressions:
Raise eyebrows, shut eyelids tightly (PT tries to open), puff out
cheeks, whistle, wrinkle nose, smile showing their teeth, frown,
scowl
-Taste from anterior 2/3
of tongue
-Parasymp visceral
motor to glands
VIII
Vestibuloco
chlear
-Paralysis of facial muscles
-impaired corneal blink reflex
-Hyperacusis (sounds v loud due to paralysis of stapedius)
Herpes zoster virus
-impairment of taste
Compression due to blood vessel
-Herpes: Facial palsy & rash in/around external auditory meatus
Stroke
-Hemifacial spasm: Continual twitching movements around mouth
& eye due to compression caused by an aberrant blood vessel
Paralysis of Stapedius muscle
-Sensory from external
ear
-Efferent limb of corneal
reflex
Hearing
Bell’s palsy (herpes simplex v.)
Vestibular
Stand behind pt & rub fingers together from 3-6” away from ear. Ask
pt to tell you when they hear something & in which ear they hear it.
Whisper 3 2-syllable words (snowflake, hot dog, ketchup) beside
each ear & ask pt to repeat the words.
Cochlear
Weber test for lateralization:
-Stroke
-Partial or complete deafness
-Dizziness, vertigo
-Nystagmus
Rap a tuning fork (256Hz or 512Hz) on your palm, the place the
vibrating fork on vertex of cranium or mid-forehead & ask the pt if
they hear the sound equally in both ears. (Will be louder on the side
with conductive hearing loss)
Rinne test for unilateral air to bone conduction:
Rap the tuning fork on your palm and place the vibrating fork on
mastoid process & ask if person hears the sound. Have pt say “now”
when the sound disappears, then place tuning fork next to ear & ask
pt if they still hear the sound. Have pt say “now” when they can no
longer hear the sound.
(pt should still hear it, unless they have conduction loss- could also
be physical object obstruction of the ear canal)
Equilibrium
Afferent limb of
Stapedius reflex
Vestibular ocular reflex:
Instruct pt to hold their thumb out at arms length and rotate head R
and L while focusing on thumb. Ask the pt if they experience any
dizziness, or if the object goes out of focus (is blurry) or if it moves
(should be still).
Gaze nystagmus:
Have person fix gaze on an object.
Balance: Romberg Test:
Dynamic Visual Acuity:
Have pt read lowest line possible on eye chart, while rotating head
side to side. Should see a drop in no more than 1-2 lines, but no
blurriness.
IX,
X
Glossophar
yngeal
Vagus
Motor to
stylopharyngeus; Taste
from post 1/3 of tongue;
sensation from skin of
external ear; sensation
from carotid body &
sinus; para motor to
parotid gland
Motor to pharynx &
larynx; para to smooth
muscle of digestive tract,
cardiac muscle;
sensation from ear;
Taste from epiglottis &
palate; visceral
sensation
Observe & palpate as the pt swallows, and note any stuttering or
delay.
-Tumors & infection affecting the
meninges
Note the quality and sound of the patient’s voice (hoarseness or
nasally?)
-Lesions due to: herpes zoster,
carotid A aneurysm, alcoholic or
diabetic neuropathy
Analyze ability to cough
Vagus: Ask pt to open mouth wide and say “ah”. Using your penlight,
look for deviation of the uvula & drooping of soft palate towards
unaffected side
Glossopharyngeal neuralgia (similar
to trigeminal neuralgia)
-Dysarthria (difficulty speaking)
-Hoarseness of speech
-Nasal speech: paralysis of soft palate muscles
-Dysphagia: Difficulty swallowing; nasal regurgitation
-Deviation of uvula towards unaffected side; soft palate droops on
the affected side (droops towards unaffected side)
-Sensory loss to skin at back of ear
Paralysis of B recurrent laryngeal nerves results in:
-Aphonia: inability to give voice
-Inspiratory stridor: harsh, high pitched sound on inspiration
Afferent & Efferent
(along with CN XI) limbs
of swallowing reflex
XI
Spinal
Accessory
-Motor to trapezius,
SCM, striated muscles of
soft palate, pharynx &
larynx
Fxn is for “head turning”
XII
Hypoglossa
l
Instrinsic & extrinsic
tongue muscles
Observe patient for muscle wasting &/or droopy shoulder(s).
Ask pt to shrug their shoulders as strong as possible while you press
down on their shoulders.
Ask pt to turn their head to side while you resist with your hands (CL
SCM)
If supine, can have lift head for bilateral SCM contraction.
Lesions due to:
-Surgical procedures of the neck
-Trauma
-Herpes zoster virus
Trap reflex: only if person can’t follow commands. Place your thumb
on muscle belly & tap nailbed.
Whiplash
Tongue protrusion:
Instruct pt to stick out their tongue & move it side to side.
-Pathologies to the basal meninges
-Tongue deviates towards side of lesion
-Neck operations
-Tongue atrophy
Speech articulation:
Listen for dysarthria- have pt repeat “Late Night Down Town”
-Ipsilateral SCM & trap weakness
-Drooping of shoulder
-Scapular winging when arms at sides
Tumors near jugular foramen
-Dysarthria