Cranial Nerve Assessment
Cranial Nerve
I. Olfactory
Forebrain
II. Optic
Forebrain
Function
The olfactory nerve carries
impulses for the sense
of smell.
The optic nerve carries
impulses for the sense of
sight.
PERRLA
III. Oculomotor
Midbrain
The oculomotor nerve is
responsible
for motor enervation of
upper
eyelid muscle, extraocular
muscle and pupillary
muscle.
PERRLA
Assessment Technique
Ask client to close their eyes, occlude
one naris at a time, and identify a
familiar smell with their eyes closed
(don’t use alcohol wipe as noxious
odors can stimulate CN V causing a
misleading response)
Visual acuity:

Snellen Chart – use to
screen for myopia (impaired
far vision). Have client stand
20 feet from the Snellen
chart. Evaluate both eyes
and then each eye
separately with and without
correction by covering each
eye. Ask the client to reach
the smallest line of print
visible, note the smallest
line the client can read
correctly

Snellen E Chart is for clients
who can’t read (picture
chart)

Rosembaum chart – Hold
14in form the client’s face
to screen for presbyopia
(impaired near vision) or
farsightedness.

If not chart – ask to read a
newspaper or count their
fingers

Ishihara – for color
blindness and shaded
shapes
Visual fields:

Face the client at a distance
of 60cm (2ft). The client
covers one eye while you
cover your direct opposite
eye. Ask the client to look at
you and report when she
can se the fingers on your
outstretched arm coming in
from four directions (up,
down, temporally, nasally)

Also check for strabismus:
cover one eye, ask client ot
look in another direction.
Move the cover and expect
both eyes to be looking in
the same direction.
Pupils equal and round, CN III
controls pupillary size
Pupil reaction to light:
Using a penlight and approaching
from the side, shine a light on the
pupil. Observe the response of the
illuminated pupil (direct response).
Shine the light on the pupil again, and
observe the response of the other
Normal Response
Client can identify
different smell with
each nostril separately
and with eyes closed
unless such condition
like colds is present.
The client should be
able to reach with each
eye and both eyes.
Should be able to see
the fingers at the same
time you can.
Abnormal Response
Loss of visual fields
Asymmetric corneal light
reflex
Periorbital edema
Conjunctivitis
Corneal abrasion
Illuminated and nonilluminated pupil
should constrict.
pupil (consensual response). Do in
BOTH eyes.
Pupil reaction to accommodation:
Ask client to look at a near object and
then at a distant object. Alternate the
gaze from the near to far
Extraocular movements (EOM):
Ask the client to follow your fingers
through the 6 cardinal field fields of
gaze in a wide “H” pattern; keep the
finger a a distance of ~30 cm (1 in)
IV. Trochlear
The trochlear
nerve controls an
extraocular muscle.
V. Trigeminal
The trigeminal nerve is
responsible for sensory
enervation of the face and
motor enervation to
muscles
of mastication (chewing).
Midbrain
Pons
Extraocular movements (EOM):
Have the client follow your finger with
his eyes without moving his head
through the 6 cardinal fields of gaze.
Move your finger in a wide “H” pattern
about 20-25cm (7.9in-9.8in) to from
the client’s eyes.
Corneal Light Reflex (PERRLA):
Shine light in the client’s eye and look
to see if the reflection is symmetric on
the corneas. This should also elicit a
blinking response which protects the
eyes.
Motor:
Ask client to clench their teeth while
you palpate the masseter and temporal
muscle to test the strength of muscle
contraction.
Cranial Nerve
VI. Abducent
Caudal Pons
VII. Facial
Caudal Pons
Function
The abducent
nerve enervates a muscle,
which moves the eyeball.
The facial nerve enervates
the muscles of the face
(facial expression) and
taste
Sensory:
Have client close their eyes and touch
the face gently with a wisp of cotton.
Ask the client to tell you when they
feel the touch.
Assessment Technique
Screen for strabismus with the
cover/uncover test. While covering one
eye, ask the client to look in another
direction. Remove the cover and
expect both eyes to be gazing in the
same direction.
Have the client follow your finger with
his eyes without moving his head
through the 6 cardinal fields of gaze.
Move your finger in a wide “H” pattern
about 20-25cm (7.9in-9.8in) to from
the client’s eyes.
Motor:
Ask the client to smile, frown, puff out
the cheeks, raise the eyebrows, close
their eyes tightly, and show their teeth.
Taste (anterior tongue):
Ask client to close their eyes and
identify foods you place on the tongue
(sweet and salty is on the anterior)
Pupils dilate to look at
an object far away and
then converse and
construct to focus on a
near object.
Eye movements should
be smooth without
nystagmus or jerking. A
couple of small jerks or
beats of nystagmus are
expected in far lateral
gaze.
Smooth symmetric eye
movements with no
jerky tremor-like
movements
(nystagmus)
Joint movement should
be smooth
Client should be able to
feel the touch
Normal Response
Both eyes are gazing in
the same direction
Smooth symmetric eye
movements with no
jerky tremor-like
movements
(nystagmus)
Client should be able to
perform all movements
with ease.
Abnormal Response
VIII.
Vestibulocochlear
Caudal Pons
The vestibulocochlear
nerve is responsible for
the sense
of hearing and balance (bo
dy position sense).
Whisper test
Rinne test:
Bone conduction – place vibrating
tuning fork firmly against the mastoid
bone. Have client state when he can no
longer hear the sound
Air conduction – then move the tuning
fork in front of the ear canal. When the
client can no longer hear the tuning
fork sound, not the length of time the
sound was heard.
Weber test:
Place a vibrating tuning fork on top of
the client’s head. Ask whether the
client can hear the sound best in the
right ear, left ear, or both ears equally.
The client can hear you
whisper softly from 3040 cm (1 – 2 ft) away.
Air conduction sound
longer than bone
conduction sound 2:1
ration.
The client hears sound
equally in both ears
(negative Weber test).
Observe gait for balance
IX.
Glossopharyngeal
Middle Medulla
X. Vagus
Caudal Medulla
XI. Accessory
XII. Hypoglossal
Caudal Medulla
The glossopharyngeal
nerve enervates
muscles involved in
swallowing and taste.
Lesions of the ninth nerve
result in difficulty
swallowing and
disturbance of taste.
Swallowing:
Ask client to swallow after providing a
sip of water
Motor to pharynx
(swallowing)
Sensory to pharynx
Taste (posterior tongue):
Ask client to close their eyes and
identify foods you place on the tongue
(sweet and sour in on posterior)
Movement of Soft palate:
Check that the uvula is midline and
rises when the client says “ahh” and
also observe pharynx and palate for
movement.
Motor to vocal cords
Listen for hoarseness of voice
PNS innervation to heart,
lungs, and abdominal
organs
Assess pulse, bowel sounds
The accessory
nerve enervates the
sternocleidomastoid
muscles and the trapezius
muscles.
The hypoglossal
nerve enervates the
muscles of the tongue.
ROM:
Place hands on the client’s shoulders
and ask them to shrug their shoulders
against resistance; then turn the head
against resistance of your hand.
Movement:
Ask the client to move the tongue up,
down, and side to side.
The vagus nerve enervates
the gut (gastrointestinal
tract), heart and larynx.
Gag reflex:
Use a tongue blade to stimulate the
back of the throat – explain before
doing.
Strength:
Apply resistance against each cheek
while the client sticks the tongue into
each cheek.
Client can articulate a phrase such as
“light, tight, dynamite”
Palate moves with
vocalization
Client gags when
tongue is stimulated
with the tongue blade
Neck should be able to
move against the
resistance.
The tongue should
move freely