Dr. Michael P. Gillespie
Cranial Nerve Evaluation
1
Brain Stem
 Between the brain and spinal cord.
 3 regions.
 Medulla oblongata.
 Pons.
 Midbrain.
2
Dr. Michael P. Gillespie
Medulla Oblongata
 A continuation of the spinal cord.
 Sensory (ascending) tracts and motor (descending) tracts
travel through the white matter of the medulla.
 Many nerves decussate (cross over) in the medulla.
3
Dr. Michael P. Gillespie
Medulla Oblongata
 Cardiovascular center regulates the heartbeat and the
diameter of the blood vessels.
4
Dr. Michael P. Gillespie
Medulla Oblongata
 The medullary rhythmicity area adjusts the rhythm of the
breathing and controls reflexes for vomiting, coughing,
and sneezing.
5
Dr. Michael P. Gillespie
Medulla Oblongata
 The nuclei for the following cranial nerves reside in the
medulla:
 VIII (vestibulocochlear).
 IX (glossopharyngeal).
 X (vagus).
 XI (accessory).
 XII (hypoglossal).
6
Dr. Michael P. Gillespie
Pons
 Pneumotaxic area and apneustic area regulate breathing.
 Nuclei for cranial nerves V (trigeminal), VI (abducens),
and VII (facial).
7
Dr. Michael P. Gillespie
Midbrain
 The midbrain or mesencephalon contains the
superior colliculi (visual actvities) and inferior
colliculi (auditory pathways).
 The midbrain contains the substantia nigra
which release dopamine to help control
subconscious muscle activities. Loss of these
neurons results in Parkinson disease.
 Cranial nerves III (oculomotor) and IV
(trochlear) originate here.
8
Dr. Michael P. Gillespie
9
Dr. Michael P. Gillespie
10
Dr. Michael P. Gillespie
11
Dr. Michael P. Gillespie
12
Dr. Michael P. Gillespie
13
Dr. Michael P. Gillespie
Cranial Nerve I - Olfactory
 Type: sensory.
 Function: smell.
 Anosmia – loss of sense of smell.
 Does not connect with the brainstem.
14
Dr. Michael P. Gillespie
15
Dr. Michael P. Gillespie
Cranial Nerve II – Optic Nerve
 Type: sensory.
 Function: vision.
 Anopia – blindness in one or both eyes.
16
Dr. Michael P. Gillespie
Cranial Nerve III - Oculomotor
 Type: mixed (mainly motor).
 Function: movement of the upper eyelid and
eyeball. Accomodation of the lens for near vision
and constriction of the pupil.
 Strabismus – deviation of the eye in which both
eyes don’t focus on the same object.
 Ptosis – drooping of the upper eyelid.
 Diploia – double vision.
17
Dr. Michael P. Gillespie
Cranial Nerve IV – Trochlear Nerve
 Type: mixed (mainly motor).
 Function: movement of the eyeball.
 Diplopia and strabismus occur with trochlear nerve
damage.
18
Dr. Michael P. Gillespie
19
Dr. Michael P. Gillespie
Cranial Nerve V – Trigeminal Nerve
 Type: mixed.
 Function: conveys impulses for touch, pain, temperature
and proprioception. Chewing.
 Trigeminal neuralgia (tic douloureux) – pain to branches
of the trigeminal nerve.
 Dentists apply anesthetic to branches of this nerve.
20
Dr. Michael P. Gillespie
21
Dr. Michael P. Gillespie
Cranial Nerve VI - Abducens
 Type: mixed (mainly motor).
 Function: movement of the eyeball.
 With damage to this nerve the eye cannot move laterally
beyond the midpoint and usually points medially.
22
Dr. Michael P. Gillespie
23
Dr. Michael P. Gillespie
Cranial Nerve VII – Facial Nerve
 Type: mixed.
 Function: Propriception and taste. Facial expression.
Secretion of saliva and tears.
 Injury produces bell’s palsy (paralysis of facial muscles).
24
Dr. Michael P. Gillespie
25
Dr. Michael P. Gillespie
Cranial Nerve VIII – Vestibulocochlear
Nerve
 Type: mixed (mainly sensory).
 Function: conveys impulses for equilibrium and hearing.
 Injury can cause vertigo, ataxia (muscular incoordination),
nystagmus (rapid movement of the eyeball), and tinnitus.
26
Dr. Michael P. Gillespie
Cranial Nerve IX – Glossopharyngeal
Nerve
 Type: mixed.
 Function: taste and somatic sensations from the posterior
1/3 of the tongue. Elevates the pharynx during swallowing
and speech. Stimulates the secretion of saliva.
 Injury causes decreased salivary secretion, loss of taste,
and difficulty swallowing.
27
Dr. Michael P. Gillespie
28
Dr. Michael P. Gillespie
Cranial Nerve X – Vagus Nerve
 Type: mixed.
 Function: taste and somatic sensations. Swallowing,
coughing, and voice production. Regulates GI tract and
heart rate.
 Injury interferes with swallowing, paralyzes vocal cords,
and causes the heart rate to increase.
29
Dr. Michael P. Gillespie
30
Dr. Michael P. Gillespie
Cranial Nerve XI – Accessory Nerve
 Type: mixed (mainly motor).
 Function: Proprioception. Swallowing, movement of head
and shoulders.
 If the nerves are damaged the SCM and Trapezius become
paralyzed.
31
Dr. Michael P. Gillespie
32
Dr. Michael P. Gillespie
Cranial Nerve XII – Hypoglossal Nerve
 Type: mixed (mainly motor).
 Function: Proprioception. Movement of the tongue
during speech and swallowing.
 Injury results in difficulty in chewing, speaking, and
swallowing. When protruded, the tongue curls towards
the affected side and atrophies on the affected side.
33
Dr. Michael P. Gillespie
34
Dr. Michael P. Gillespie
Cranial Nerves
 I – Olfactory
 VII – Facial
 II – Optic
 VIII – Auditory
(Vestibulocochlear)
 III – Oculomotor
 IX – Glossopharyngeal
 IV – Trochlear
 X – Vagus
 V – Trigeminal
 XI – Spinal accessory
 VI – Abducens
 XII - Hypoglossal
35
Dr. Michael P. Gillespie
Cranial Nerves
 On Old Olympus’ Towering Tops A Fin And German
Viewed Some Hops.
 This mnemonic device helps you memorize the names of
the cranial nerves.
 The first letter from each word corresponds to the first
letter of each cranial nerve.
36
Dr. Michael P. Gillespie
Cranial Nerves
 Some Say Marry Money, But My Brother Says Big Brains
Matter Most.
 This mnemonic device helps you memorize the sensory /
motor distribution of the cranial nerves.
 S = sensory
 M = Motor
 B = Both
37
Dr. Michael P. Gillespie
Cranial Nerves
 Twelve pairs of cranial nerves exit from the brain and
brainstem.
 These nerves innervate the face, head, and neck.
 They control all sensory and motor functions in these areas
including the special senses of vision, hearing, smell, and
taste.
 Cranial trauma, infections, aneurysm, stroke, degenerative
diseases (i.e. multiple sclerosis), upper motor neuron
lesions, lower motor neuron lesions, increased intracranial
pressure, and abnormal masses or tumors can all affect the
cranial nerves.
38
Dr. Michael P. Gillespie
Unilateral and Bilateral Innervation
 Some facial movements are performed in bilateral
synchrony such as swallowing and moving the forehead
and are thus innervated bilaterally.
 Fine movements of the face are unilateral. The
contralateral hemisphere innervates the affected area.
39
Dr. Michael P. Gillespie
Olfactory Nerve (I) Testing
 To test this nerve, obtain some aromatic substance such as
coffee, tobacco, or peppermint oil.
 Instruct the patient to close one nostril.
 Place the substance under the open nostril and ask what
the patient smells if anything.
 Repeat the procedure for the opposite nostril.
40
Dr. Michael P. Gillespie
Olfactory Nerve (I) Testing
41
Dr. Michael P. Gillespie
Olfactory Nerve (I) Testing
 If the patient cannot smell or identify the smell
unilaterally, suspect a lesion of the olfactory nerve.
 If the patient cannot smell or identify the smell bilaterally,
consider a nonorganic problem or a bilateral cranial nerve I
lesion.
42
Dr. Michael P. Gillespie
Olfactory Nerve (I) Testing
 A diminished or almost absent sense of smell is common
in the elderly. This will be apparent if the loss of sense of
smell is bilateral and the cranium has not undergone a
trauma.
 Other nonneurogenic lesions such as a sinus infection,
deviated septum, and lesions caused by smoking nay also
cause a loss of smell.
43
Dr. Michael P. Gillespie
Optic Nerve (II) Testing
 The optic nerve is responsible for visual acuity and
peripheral vision.
 To test for visual acuity, ask the patient to cover one eye
and read the smallest print possible on a Snellen chart.
 Repeat the test with the opposite eye.
 This is not a test for visual acuity and refractive errors of
the eye. We are testing the acuity for optic nerve
involvement. Consequently, we can perform the test with
the patient wearing glasses or contact lenses.
44
Dr. Michael P. Gillespie
Optic Nerve (II) Testing
 To test for peripheral vision, ask the patient to cover one
eye with the hand and keep a fixed gaze on your nose with
the uncovered eye.
 Directly motion a large cross with your finger from
superior to inferior and from right to left.
 Instruct the patient to tell you when he or she begins to see
your finger.
 Repeat with the opposite eye.
 Record results.
45
Dr. Michael P. Gillespie
Optic Nerve (II) Testing
 Any loss of vision from a complete unilateral or bilateral
loss of vision, loss of half fields of vision (hemianopsia), or
a partial defect in the field of vision (scotoma) indicates an
optic nerve lesion.
 A temporal lobe lesion can produce a superior
contralateral quadrantanopsia.
 An occipital lobe lesion can produce a contralteral
homonymous hemianopsia with macula sparing.
46
Dr. Michael P. Gillespie
Optic Nerve (II) Testing
47
Dr. Michael P. Gillespie
Optic Nerve (II) Testing
48
Dr. Michael P. Gillespie
Optic Nerve (II) Testing
49
Dr. Michael P. Gillespie
Oculomotor (III), Trochlear (IV) &
Abducens (VI) Nerve Testing
 Cranial nerves III, IV, and VI are all associated with ocular
and pupillary motility.
 They are testing together for simplicity.
 Cranial nerve II also innervates the levator palpebrae
muscles, which are responsible for movement of the
eyelids.
50
Dr. Michael P. Gillespie
Oculomotor (III), Trochlear (IV) &
Abducens (VI) Nerve Testing
 First, look at your patient and observe for any ptosis.
 Next inspect the eye globes for alignment.
 Next, inspect the pupils and determine their size and
shape.
51
Dr. Michael P. Gillespie
Oculomotor (III), Trochlear (IV) &
Abducens (VI) Nerve Testing
 Test the pupillary reflex by flashing a light into one of the
patient’s eyes. Look at the pupils one at a time for dilation
and contraction.
 Test ocular movements. Have the patient follow either
your finger or a moving object through the entire field of
vision in all axes.
 Observe for nystagmus and / or the inability to move the
eye on a particular direction.
 Test for convergence by having the patient look at a distant
object and continue to focus on it as you move it closer to
the patient.
Dr. Michael P. Gillespie
52
Oculomotor (III), Trochlear (IV) &
Abducens (VI) Nerve Testing
 Oculomotor nerve lesion
 Causes ptosis of the eyelid with inability to open the lid.
 Eye alignment may be down and lateral.
 The patient will be unable to move the eyeball upward,
inward, or downward due to weakness of the medial,
superior, and inferior rectus muscles.
 Pupil is usually dilated and the pupillary reflex is absent.
 The most frequent cause is an aneurysm in the circle of
Willis.
53
Dr. Michael P. Gillespie
Oculomotor (III), Trochlear (IV) &
Abducens (VI) Nerve Testing
 Trochlear nerve lesion
 Causes superior and lateral deviation of the eye with inability
to move the eyeball downward and inward because of
weakness of the superior oblique muscle.
 Aducens nerve lesion
 Causes inability to move the eyeball outward because of
weakness of the lateral rectus muscle.
54
Dr. Michael P. Gillespie
III, IV, and VI Testing
55
Dr. Michael P. Gillespie
III, IV, and VI Testing
56
Dr. Michael P. Gillespie
III, IV, and VI Testing
57
Dr. Michael P. Gillespie
III, IV, and VI Testing
58
Dr. Michael P. Gillespie
III, IV, and VI Testing
59
Dr. Michael P. Gillespie
III, IV, and VI Testing
60
Dr. Michael P. Gillespie
III, IV, and VI Testing
61
Dr. Michael P. Gillespie
Trigeminal Nerve (V)
 The trigeminal nerve is composed of motor and sensory
portions.
 The motor portion innervates the muscles of mastication
(masseter, pterygoid, and temporal muscles).
 The sensory portion is divided into three branches:
opthalmic (V1), maxillary (V2), and mandibular (V3).
62
Dr. Michael P. Gillespie
Trigeminal Nerve (V)
 Motor
 Masseter – instruct the patient to simulate a bite while you
palpate the masseter and attempt to open the patients jaw
with your thumbs.
 Pterygoid – instruct the patient to deviate the jaw against
your resistance.
 Temporalis – instruct the patient to clench the jaw while you
palpate the temporalis with your fingers.
63
Dr. Michael P. Gillespie
Trigeminal Nerve (V)
 A weak masseter or pterygoid may indicate a trigeminal nerve
lesion. A difference in tension in the temporalis may indicate a
lesion.
 In b/l paralysis, the jaw may not close tightly.
 In unilateral paralysis, the jaw deviates towards the side of the
lesion.
64
Dr. Michael P. Gillespie
Trigeminal Nerve (V)
 Reflex
 Corneal reflex – instruct the patient to gaze upward and
inward while you touch the cornea with a strand of cotton,
approaching from the lateral side. Do not touch the eyelash
or conjunctiva.
 The patient should blink when the cornea is touched.
 Sensory from trigeminal nerve, from the facial nerve.
 Jaw reflex – instruct the patient to open the mouth slightly.
Place your thumb or index finger just lateral to the midline.
Tap down to open the jaw with your reflex hammer.
 The patient should close the jaw rapidly.
 Sensory and motor from trigeminal nerve.
65
Dr. Michael P. Gillespie
Trigeminal Nerve (V)
 Sensory
 Patient eyes closed. Touch the forehead, cheek, and chin
with a pin for pain sensation; a piece of cotton for the
sensation of light touch; small test tubes of hot an cold water
for thermal sensations. Compare b/l.
 Touch the tongue, inside of both cheeks, and the hard palate
with a tongue depressor. Have the patient give a signal upon
feeling the sensation.
 Decreased sensation indicates a lesion of that sensory branch
of the trigeminal nerve in the affected region.
66
Dr. Michael P. Gillespie
Trigeminal Nerve (V) Testing
67
Dr. Michael P. Gillespie
Trigeminal Nerve (V) Testing
68
Dr. Michael P. Gillespie
Trigeminal Nerve (V) Testing
69
Dr. Michael P. Gillespie
Trigeminal Nerve (V) Testing
70
Dr. Michael P. Gillespie
Trigeminal Nerve (V) Testing
71
Dr. Michael P. Gillespie
Facial Nerve (VII)
 Motor
 The facial nerve has both motor and sensory fibers.
 The motor fibers innervate the muscles of the face and the
platysma.
 Observe for abnormal movements, tics or tremors. Note the
degree of change or lack of change of expression.
 Observe the face in repose. Instruct the patient to frown,
raise the eyebrows, close the eyes, show the teeth, smile, and
whistle or puff the cheeks.
72
Dr. Michael P. Gillespie
Facial Nerve (VII)
 Sensory
 Instruct the patient to close the eyes and protrude the
tongue. Apply solutions of sugar, salt, and/or vinegar to one
side and on the anterior two-thirds of the tongue. Ask the
patient to identify each substance without retracting the
tongue (point to a list). Rinse the mouth and apply on
opposite side.
73
Dr. Michael P. Gillespie
Facial Nerve (VII) Testing
74
Dr. Michael P. Gillespie
Vestibulocochlear Nerve (VIII)
 Weber’s Test: Cochlear Nerve
 Place a tuning fork on top of the patient’s head. Ask if the
patient hears it the same in both ears. If it is louder in one
side than the other suspect a conduction problem. If it is
heard only in one side, suspect a cochlear nerve lesion.
 Rinne’s Test: Cochlear Nerve
 Place a vibrating tuning fork on the mastoid process. Ask the
patient to say when the sound disappears. After the sound
disappears place the tuning fork next to, but not touching the
ear. See when the sounds fades out.
 Normally, air conduction is twice as loud as bone conduction
(Rinne positive). In conduction lesions and non-neurogenic
lesions, bone conduction is greater than air conduction
(Rinne negative).
75
Dr. Michael P. Gillespie
Vestibulocochlear Nerve (VIII)
 Veering Test: Vestibular nerve
 Instruct the patient to walk with eyes closed.
 Veering on walking or a positive Romberg’s test indicates a
unilateral vestibular lesion.
76
Dr. Michael P. Gillespie
Glossopharyngeal and Vagus Nerves
(IX, X)
 Sensory
 Patient closes eyes and protrudes tongue. Apply a bitter
tasting solution to the posterior third of the tongue. Have
the patient identify each substance without retracting the
tongue.
 Reflex (Gag reflex)
 With a throat stick, touch the posterior pharyngeal wall, first
on one side, then on the other. Observe the moment when
the patient gags and ask him whether the sensation is
stronger on one side or the other.
77
Dr. Michael P. Gillespie
Glossopharyngeal and Vagus Nerves
(IX, X)
78
Dr. Michael P. Gillespie
Spinal Accessory Nerve (XI)
 The spinal accessory nerve innervates the trapezius and
the sternocleidomastoid muscles. To test the nerve, test
these muscles.
 Trapezius
 Patient seated, apply pressure to the patient’s shoulders
bilaterally and ask him to shrug against resistance.
 SCM
 Patient seated, place your hand on the lateral aspect of the
patient’s jaw, instruct him to turn the head toward your hand
against resistance.
79
Dr. Michael P. Gillespie
Spinal Accessory Nerve (XI)
80
Dr. Michael P. Gillespie
Hypoglossal Nerve (XII)
 The hypoglossal nerve is purely motor and is responsible
for movement of the tongue.
 Place your hand on the patient’s cheek and instruct him to
press the tip of the tongue against the cheek under your
hand. Repeat b/l. Instruct the patient to protrude the
tongue.
 If the pressure is unequal, suspect a unilateral hypoglossal
nerve lesion. The tongue will deviate towards the side of
the lesion.
81
Dr. Michael P. Gillespie
Hypoglossal Nerve (XII)
82
Dr. Michael P. Gillespie