Leicester Medical School
THE NERVOUS SYSTEM
EXAMINATION OF THE CRANIAL NERVES
Overview
The cranial nerves are examined in order:
-
I Olfactory
II Optic
III, IV &VI Oculomotor, Trochlear & Abducens
V Trigeminal
VII Facial
VIII Vestibulocochlear
IX & X Glossopharyngeal & Vagus
XI Accessory
XII Hypoglossal
Preparation
-
-
Wash your hands
Introduce yourself to the patient if you have not already done so and check the
identity of the patient
Ask the patients permission to carry out the examination
Give a brief explanation to the patient before you start. Further
explanation/instructions can be given as you proceed.
Equipment
o Snellen Chart (or a sample of type written text)
o Pen torch
o Cotton Wool
o Opthalmoscope
o 256Hz or 512Hz Tuning Fork
Patient position
o Ideally the patient should be sitting at the same level as the examiner
General Observations
-
Check visually from the end of the bed. Note:
o Muscle wasting, fasciculations or tremor
o Facial asymmetry or loss of expression
o Ptosis, strabismus
o Salivation
o Obvious discomfort or pain
Cranial Nerve 1 – Olfactory
-
Ask the patient if they have noticed any change or loss of their sense of smell
Cranial Nerve 2 – Optic
Visual Acuity
- If patient wears glasses, they should keep them on for testing acuity
- Ask the patient to cover one eye and read a sample of text with the other.
o Formally tested with a Snellen Chart
o Magazines or books can be used at the bedside
- Repeat with the other eye.
- Note any significant difference between the eyes
Visual Fields
- Sit directly opposite the patient with your eyes at the same level
- Ask the patient to cover their right eye with the right hand
- Cover your own left eye with your left hand.
- Ask the patient to look directly into your exposed eye as you do the same
- Extend your right arm fully and bring in your right hand in slowly from the periphery
while moving the index and middle fingers. Keep your hand midway between
yourself and patient
- Ask the patient to tell you when they first can see your fingers
o You should both see them at the same time.
o If finger movements are not detected, continue movement toward the centre
of vision until the patient sees them
- Repeat for all quadrants of the visual field of the patients right eye
- Repeat for the other eye
Fundoscopy
- You should be aware that inspection of the eye optic
nerve head (or optic disc) using an ophthalmoscope
would normally be expected as part of a cranial
nerve examination.
- You will learn this skill in Phase II
Pupillary Response - Light reflex
- Shine light into the right eye
- Look for constriction in the pupil of both the
illuminated eye (direct reflex) and equal constriction
in the contra lateral eye (consensual reflex)
- Repeat for the left eye
Pupillary Response – The
Optic Nerve is purely
sensory. The Oculomotor
nerve supplies the
sphincter muscles of the
iris causing constriction of
the pupil and the ciliary
muscle which focuses the
lens for near vision
Pupillary Response - Accommodation
- Hold your index finger up about a meter from the patient
- Ask the patient to focus on your finger while you advance it toward their nose
- Watch for constriction of the pupils in response to convergence and accommodation
Cranial Nerves 3, 4 & 6 – Oculomotor, Trochlear and Abducens
-
The patient should sit facing you with their eyes looking straight ahead
Inspect the position of the eyelids for ptosis
Note the position of the eyes in the resting gaze
Ask the patient to follow the movement of your index finger with their head still,
moving their eyes only.
Move your index finger in an H shape in front of the patient so that the patients eyes
are seen to move fully to right, left, superior, inferior and oblique.
o look for extra ocular palsy and nystagmus
o ask the patient to tell you if they have any double vision
o Avoid extremes of gaze as this can cause a physiological nystagmus
Cranial Nerve 5 - Trigeminal
Sensory
- Lightly touch the patients face with cotton wool in the ophthalmic, maxillary and
mandibular divisions, comparing each side.
- Corneal reflex
o This is uncomfortable, so may be omitted if a lesion is not suspected.
o Ask the patient to look up to the ceiling and gently pull down the lower eyelid
o Very lightly touch the lateral edge of the cornea with a wisp of damp cotton
wool
o Look for direct and consensual blinking
o It is important to touch the sensitive cornea and not the insensitive sclera.
Motor
- Inspect for any obvious wasting of the muscles of mastication
- Ask the patient to clench their teeth
- Feel for contractions of temporalis muscles and also the masseter muscles at the
angle of the jaw.
- Ask the patient to open their jaw and to keep it open. Try and close the patient‟s
mouth – the pterygoids are strong; you should not be able to overcome the
movement
- Ask the patient to move jaw side to side (pterygoid muscles) and look for equal
movement
Cranial Nerve 7 – Facial
Inspect for any asymmetry with the patient
Conductive Deafness If the air
relaxed
passages are blocked or in the
- Ask the patient to raise their eyebrows as high
presence of middle ear disease then
as they can, whilst you gently push down
(frontalis muscle).
air conduction will be reduced but
- Ask the patient to screw up their eyes and
perception of sound through bone
resist you opening them (Orbicularis
conduction
will be
preserved.
Abducens
innervates
lateral
rectus
oculi)
Rinne’s
test will
negative
muscles
- damage
willbegive
weak(bone
- Ask the patient to smile and show their
louder than air
lateral conduction
gaze
teeth (Orbicularis Oris)
Trochlear
nerve innervates right and
conduction).
- Ask the patient to blow out their cheeks
left superior
oblique
muscles
- itsis louder
Weber’s
test will
find sound
(Buccinators)
action in
is the
demonstrated
affected ear.by asking
o weakness can be exaggerated by
the patient to look downwards and
tapping the cheek and checking
inwards
for continence of air
Oculomotor nerve innervates all
remaining ocular muscle and the
Cranial Nerve 8 – Vestibulocochlear
levator palpebrae superioris,
weakness in which results in ptosis.
Simple Test of Hearing
-
-
-
Whisper in each of the patients ears in turn
(whilst covering the other), and ask them to
repeat what is said.
Alternatively, make a noise in each ear in
turn (e.g. rub fingers against thumb) and ask
the patient so say when you stop.
Rinne’s test
- Tap a 256 or 512Hz tuning fork
- Hold adjacent to the right ear, say “This is
sound 1”
- Apply base of tuning fork to mastoid process,
say “This is sound 2”
- Ask the patient which sound is the loudest
- Repeat for the left ear
Sensorineural Deafness
If the auditory nerve or cochlear is
affected then the perception of sound
through both air and bone
conduction will be reduced.
Rinne’s test will be positive (air
conduction louder than bone
conduction).
Weber’s test will find sound is louder
in the unaffected ear.
Weber’s Test
- Tap a 256 or 512Hz tuning fork
- Hold the base centrally against the forehead
- Ask, “Does it sound louder on one side, or is it the same
on both sides?”
In a normal individual Rinne‟s Test will be positive, i.e. air
conduction (sound 1) will be louder than bone conduction
(sound 2). Weber‟s test will find the sound to be perceived
equally by both ears.
Cranial Nerves 9 & 10
are tested together as
they work together to
control the larynx,
pharynx and swallow.
Cranial Nerves 9 & 10 Glossopharyngeal and Vagus
-
Ask the patient to cough (damage gives a „bovine‟ cough)
Ask the patient to open the mouth. Inspect the soft palate and uvula. The uvula
should be central
Ask the patient to say „Aaah.‟ The uvula and soft palate should move upwards and
not deviate to one side
Gag reflex
o This is not usually tested in the conscious patient
o Touch the posterior pharyngeal wall on one side with a sterile stick
o The uvula and soft palate should rise with the gag reflex N.B. You may not be
able to visualise the uvula in the case of a strong gag reflex
o Repeat on the other side of the posterior pharyngeal wall
o Ask if the patient felt the touch equally on both sides
Cranial Nerve 11 Accessory
Cranial Nerve 11 innervates the upper fibres of trapezius and the sternomastoid muscles.
- Ask the patient to shrug their shoulders using your hands on their shoulders to resist
the movement.
- Ask the patient to turn their head to each side using your hand on their cheek to
resist the movement
- Note any asymmetry
Cranial Nerve 12 Hypoglossal
-
Ask the patient to open the mouth
Inspect the tongue for wasting and fasciculation
Ask the patient to protrude the tongue and look for deviation
Ask them to move the tongue from side to side
Place your finger on the patient‟s cheek and ask them to push against it using their
tongue. Repeat for the other side.
Completing the Examination
-
Thank the patient
For completion you should also consider:
o Neurological examination of the limbs
o Mental state examination