TRANSCRIBED BY: LUKE, LEIA, HAN, CHEWBACCA

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Alfredo Guzman, M.D.

What makes earth feel like hell is our expectation that it should feel like heaven Chuck Pahlaniuk, Damned Paulo Coelho

CRANIAL NERVES

2.6 08 Sept

2014

CRANIAL NERVE

12 pairs of specialized nerves within the skull or cranium o CN I and II fiber tracts emerging from the brain o CN III XII from the diencephalon and brainstem (midbrain,

pons, medulla)

Remember!

Jan 28, 1975

Jan 28 stands for cranial nerve I, II and VIII which are all sensory

1975 means cranial nerves V, VII, IX and X which are all both sensory and motor.

The rest are motor.

CN Name Function Examinations

Used

I Olfactory Sensory Smell

II Optic Sensory Visual Acuity

Visual Fields Ocular Fundi

Pupillary Reactions

III Oculomotor Motor Pupillary Reactions

Extraocular Movements

IV Trochlear Motor Extraocular Movements

V Trigeminal Both Corneal Reflexes

Facial Sensation Jaw Movements

Voice and Speech

VI Abducens Motor Extraocular

Movements

VII Facial Both Facial Movements

VIII Vestibulocochlear

or Auditory (Acoustic)

Sensory Hearing

Voice and Speech

IX Glossopharyngeal Both Swallowing and

Rise of the Palate

Gag Reflex

X Vagus Both Swallowing and Rise of the Palate

Gag Reflex

Voice and Speech

XI Accessory or Spinal Accessory

Motor Shoulder and Neck Movements

XII Hypoglossal Motor Tongue Symmetry and Position

Summary of CN Examination (from bates 11th Ed.)

American Academy of Neurology : Guidelines for Screening Neurologic Examination o Cranial Nerves

Visual Acuity Pupillary Light Reflex Eye Movement Hearing Facial Strength smile, eye closure

CRANIAL NERVE I OLFACTORY NERVE

Special afferent cranial nerve composed of sensory fibers only

Sole function: To discern smells

Olfaction depends on: o Integrity of the olfactory neurons in the roof of the nasal cavity o Their connections through the olfactory bulb, tract, and stria to

the olfactory cortex of the medial frontal and temporal lobes.

Olfaction is frequently not tested because of unreliable patient responses and lack of objective signs.

TEST FOR OLFACTION

Present familiar and non-irritating odors

First be sure that each nasal passage is open by compressing of the nose and asking to sniff through the other

Commonly used odorants: o Concentrated vanilla o Perfume o Coffee o Soap o Cloves

Patient should close both eyes

Occlude one nostril and test smell on the other using the odorants

Ask if the patient smells anything and, if so what

Test the other nostril

Figure 1. Testing for Olfaction

Avoid noxious triggers (ammonia) that can stimulate CN V

A person normally perceives odor on each side and can often identify it.

DISORDERS/DISTURBANCES CN I (OLFACTION)

Uncommon in neurological practice

Alteration of taste and smell o Recognized complication of head injury and can follow an upper

respiratory tract infection o Sinus conditions o Smoking o Use of cocaine

Unilateral Anosmia o Rare presenting complaint in subfrontal meningioma

Dulling of olfaction occurs in the: o Elderly o Parkinsons disease o Early feature of Alzheimers disease

QUIZ TIME! So what is the most common cause of BILATERAL ANOSMIA? ANSWER: MARAMING LAMIG. HAHAHAHAHAHA! Ang corny! :D

TOPIC OUTLINE

I. Cranial Nerves isang malaking joke ang topic outline since puro

cranial nerves lang naman :D

This trans came from upper batch trans + transcibers notes + Master

Bates :D

TRANSCRIBED BY: KYU, RYU, KINTA, MEGUMI, KAZUMA

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CRANIAL NERVES

CRANIAL NERVE II OPTIC NERVE

Contains special sensory afferent fibers that convey visual information from the retina to the occipital lobe via the visual pathway.

Figure 2. Visual Pathway

Evaluation gives important information about the o Nerves o Optic chiasm o Optic tracts o Thalamus o Optic radiations o Visual cortex

CN II is also the afferent limb of the pupillary light reflex

The optic nerve is tested by: o Visual acuity, o Color vision testing for males using Ishihara Test o Pupil evaluation o Visual field testing o Optic nerve evaluation ophthalmoscopy and/or stereo

biomicroscopy

TEST FOR VISUAL ACUITY

Allow the patient to use their glasses if available You are interested in the patient's best corrected vision

Position the patient 20 feet in front of the Snellen eye chart (or hold

a Rosenbaum pocket card at a 14 inch "reading" distance)

Have the patient cover one eye at a time with a card

Ask the patient to read progressively smaller letters until they can go no further

Record the smallest line the patient read successfully (20/20, 20/30,

etc.)

Repeat with the other eye

There are hand held cards that look like Snellen Charts but are positioned 14 inches from the patient

o Used simply for convenience o Testing and interpretation are as described for the Snellen.

Figure 3. Rosenbaum pocket card - hand held visual acuity

card (held at 14 inches from the patient)

VISUAL FIELD TEST VIA CONFRONTATION

Stand 2 feet in front of the patient and have them look into your eyes

Hold your hands about one foot away from the patient's ears, and wiggle a finger on one hand

Ask the patient to indicate which side they see the finger move

Repeat two or three times to test both temporal fields

If an abnormality is suspected, test the four quadrants of each eye while

asking the patient to cover the opposite eye with a card

PUPILLARY REACTION TO LIGHT* (CN II & CN III)

Dim the room lights as necessary

Ask the patient to look into the distance

Shine a bright light obliquely into each pupil in turn

Look for both the direct (same eye) and consensual (other eye) reactions

Record pupil size in mm and any asymmetry or irregularity

If abnormal, proceed with the test for accommodation.

PUPILLARY REACTION TO ACCOMODATION* (CN II & CN III)

Hold your finger about 10cm from the patient's nose

As the patient to alternately look into the distance and at your finger

Observe the pupillary response in each eye

Inspect the size and shape of the pupils, and compare one side with the other.

o Anisocoria, or a difference of >0.4 mm in the diameter of one pupil compared to the other.

OPTIC NERVE EVALUATION

Inspect optic fundi using an ophthalmoscope

Pay special attention to the optic disc

DISORDERS/DISTURBANCES IN CN II

DISORDERS MANIFESTATION

Optic Atrophy Disc pallor

Papilledema Disc bulging

Glaucoma Poor visual acuity Retinal Emboli

Optic Neuritis

Pituitary Tumor (defect at optic chiasm)

Bitemporal hemianopsia

Stroke, Postciasmal Lesions (usually parietal lobe)

Homonymous hemianopsia Quadrantanopsia

Normal Visual Acuity

CRANIAL III, IV, VI

Function: Extraocular movements o CN IV Superior Oblique o CN VI Lateral Rectus o CN III Superior Rectus, Inferior Rectus, Medial rectus, Inferior

Oblique

Remember! SO 4 LR 6

the remaining EOM are innervated by CN III

TEST FOR EXTRAOCULAR MOVEMENT

Test the EOM in the six cardinal directions of gaze (H pattern)

Stand or sit 3 to 6 feet in front of the patient

Ask the patient to follow your finger with their eyes without moving their head

Check gaze in the six cardinal directions using a cross or "H"

pattern

Pause during upward and lateral gaze to check for nystagmus

Check convergence by moving your finger toward the bridge of the patient's nose

Look for loss of conjugate movements in any of the six directions which causes diplopia o Ask which direction makes the diplopia worse o Inspect the eye for asymmetric deviation of movement o Do a cover-uncover test or ask the patient to cover one eye

Determines if diplopia is monocular or binocular Identify any nystagmus (Nystagmus is named for the direction of the

quick component) o Note direction of gaze in which it appears o Note plane of nystagmus

Horizontal Vertical Rotary

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CRANIAL NERVES

Mixed o Direction of quick and slow components

Ask patient to fix his/her vision on a distant object and observe if nystagmus increases or decreases

Look for ptosis

PUPILLARY REACTION TO LIGHT

Discussed earlier in CN II

DISORDERS/DISTURBANCES IN CN III, IV & VI

DISORDERS MANIFESTATIONS

Local Problems with glasses or contact lenses

Monocular diplopia

Cataracts

Astigmatism

Ptosis

CN III, IV, VI Neuropathy Binocular diplopia (40% of patients)

Myasthenia Gravis Ptosis Weakness of extraocular muscles

Cerebellar Disease Nystagmus Gait ataxia Dysarthria

Cerebellar Disease, increases with retinal fixation

Vestibular Disease, decreases with retinal fixation

Vestibular Disease

CN III Palsy Ptosis

Horners syndrome Ptosis Meiosis

Anhidrosis

CLINICAL EFFECTS OF LESIONS OF THE THIRD, FOURTH AND SIXTH OCULAR NERVE

CRANIAL NERVE III-OCULOMOTOR

Complete CN III Lesion o Ptosis (drooping of upper eyelid)

Levator palpebrae supplied by CN III o Inability to rotate the eye (weakness of the extraocular muscles)

Upward SR, IO Downward IR Inward MR

o Down and Out position of the eye due to the remaining action of CN IV and CN VI

When the lid is passively elevated o Eye is deviated outward and slightly downward

Unopposed actions of intact LR and SO o Iridoplegia (dilated nonreactive pupil) and Cycloplegia (paralysis

of accommodation) Interruption of PSNS in CN III (no PSNS)

However, extrinsic and intrinsic eye muscles may be affected separately o Infarction of central portion of CN III spares the pupil Since the PSNS preganglionic pupilloconstrictor fibers lie near

the surface Occurs in Diabetic ophthalmoplegia

Conversely, compressive lesions of CN III usually dilate the pupil as an early manifestation

After injury, regeneration of CN III fibers may be aberrant o Some of the fibers that originally moved the eye in a particular

direction now reach another muscle or the iris o If it reaches the iris, the pupil, which is unreactive to light, may

constrict when the eye is turned up and in

CN IV TROCHLEAR NERVE

Lesion of CN IV causes paralysis of SO muscle o Most common cause of isolated symptomatic vertical diplopia o Paralysis of SO muscle results in:

Weakness of downward movement of the affected eye (most marked when the eye is turned inward)

Patient complains on difficulty in reading or going down stairs

Affected eye tends to deviate slightly upward This defect may be overlooked in the presence of a third

nerve palsy if the examiner fails to note the absence of an expected intorsion as the patient tries to move the paretic eye downward

Bielchowsky Sign head tilting to the opposite shoulder o Characteristic of CN IV lesions o this maneuver causes a compensatory intorsion of the

unaffected eye and ameliorates the double vision

Unilateral Trochlear Palsies o More common

Bilateral Trochlear Palsies o Occur rarely after head trauma

o characteristic alternating hyperdeviation depending on the direction of gaze

CN VI ABDUCENS NERVE

CN VI Lesions o Abducens muscle paralysis o Weakness of lateral or outward movement as well as a crossing

of the visual axes o The affected eye deviates medially

Incomplete CN VI palsies o Turning the head toward the side of the paretic muscle

overcomes the diplopia

ANALYSIS OF DIPLOPIA

Almost all instances of diplopia (seeing a single object as double) are the result of an acquired paralysis or paresis of one or more extraocular muscles.

The signs of oculomotor palsies are manifest in various degrees of completeness.

Noting the relative positions of the corneal light reflections and having the patient perform common versional movements will usually disclose the faulty muscle(s) as the eyes are turned into the field of action of the paretic muscle.

QUIZ TIME!!

What cranial nerve is involved? Right or Left?

Figure 4. Note patient's right eye is deviated

laterally and there is ptosis of the lid.

Right CN3 Lesion: The right pupil (upper left picture)

is more dilated than the left pupil. o Disorders of the extra ocular muscles themselves (and not the

CN which innervate them) can also lead to impaired eye movement.

o An example is a patient who has suffered a traumatic left orbital injury. The inferior rectus muscle has become entrapped within the resulting fracture, preventing the left eye from being able to look downward.

CN V TRIGEMINAL NERVE

Both motor and sensory components o Sensory limb has 3 major branches, each covering roughly 1/3 of

the face Ophthalmic (V1) Maxillary (V2) Mandibular (V3)

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CRANIAL NERVES

SENSORY COMPARTMENT TESTING

TEST FOR PAIN SENSATION

Explain to the patient what you plan to do

Test the forehead, cheeks, and jaw on each side

Use a sharp implement (e.g. broken wooden handle of a cotton tipped applicator)

Ask the patient to close their eyes so that they receive no visual cues

Touch the sharp tip of the stick to the right and left side of the forehead,

assessing the Ophthalmic branch

Touch the tip to the right and left side of the cheek area, assessing the Maxillary branch

Touch the tip to the right and left side of the jaw area, assessing the

Mandibular branch

The patient should be able to clearly identify when the sharp end touches their face

Make sure that you do not push too hard as the face is normally quite sensitive.

You may also use a sharp and blunt object, asking the patient to identify if it is sharp or dull.

Test both sides of the face

If there is an abnormality, confirm by performing temperature sensation test

Figure 5. Suggested areas for Sensory Testing

TEMPERATURE SENSATION TEST

Two test tube with hot and ice cold water are commonly used

Tuning fork may also be used

Touch the skin of the patient using the objects and ask if it is hot or cold

TEST FOR LIGHT TOUCH

Use a fine wisp of cotton

Ask the patient to respond whenever you touch the skin

TEST FOR CORNEAL REFLEX

The Ophthalmic branch of CN V also receives sensory input from the surface of the eye

Ask the patient to look up and away from you

Avoid touching the eyelashes

If patient is apprehensive, touching the conjunctiva first may allay fear

Pull out a wisp of cotton.

While the patient is looking straight ahead, gently brush the wisp against the lateral aspect of the sclera (outer white area of the eye ball).

This should cause the patient to blink.

Blinking also requires that CN VII function normally, as it controls eye lid closure

Sensory is via CN V, and Motor is via CN VII

Use of contact lenses frequently diminish this reflex

cotton wisp must touch the cornea not the sclera

Figure 6. Test for Corneal Reflex

MOTOR COMPARTMENT TESTING

The motor limb of CN V innervates the Temporalis and Masseter muscles, both important for closing the jaw.

Place your hand on both Temporalis muscles, located on the lateral aspects of the forehead

Ask the patient to tightly close their jaw, causing the muscles beneath

your fingers to become taught

Then place your hands on both Masseter muscles, located just in front of the Temporo-Mandibular joints (point where lower jaw articulates with

skull)

Ask the patient to tightly close their jaw, which should again cause the muscles beneath your fingers to become taught

Then ask them to move their jaw from side to side, another function of

the Masseter.

Figure 7. Palpation of Temporal and Masseter Muscles

DISORDERS/DISTURBANCES IN CN V

DISORDERS MANIFESTATIONS

Masseter Weakness Difficulty clenching the jaw

Lateral Pterygoid Weakness Difficulty moving the jaw to the opposite side

CN V Pontine Lesions Unilateral weakness

Cerebral Hemispheric Disease

Bilateral weakness

Contralateral Cortical or Thalamic lesion

Facial and body sensory loss on the same side

Brainstem Lesion Ipsilateral face but contralateral body sensory loss

Peripheral Nerve Disorders (Trigeminal Neuralgia)

Isolated facial sensory loss

CN V or CN VII Lesion Absent blinking

Acoustic Neuroma Absent blinking Sensorineural hearing loss

CRANIAL NERVE VII FACIAL NERVE

Has both motor and sensory function o Motor innervates many of the muscles of facial expression o Sensory Chorda tympani branch contains fibers from anterior

2/3 of the tongue, along with secretomotor fibers to the submaxillary and submandibular glands

MOTOR COMPARTMENT TESTING

First look at the patients face

It should appear symmetric: o The same amount of wrinkles apparent on either side of the

forehead o The nasolabial folds should be equal o The corners of the mouth should be at the same height

Inspect both at rest and during conversation

Observe any tics or abnormal movements

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CRANIAL NERVES

If there is any question as to whether an apparent asymmetry is

new or old, ask the patient for a picture for comparison

Ask the patient to wrinkle their eyebrows and then close their eyes tightly

You should not be able to open the patients eyelids with the application of gentle upwards pressure

CN 7 controls the muscles that close the eye lids

CN 3 controls the muscles which open the eye lids

Ask the patient to smile.

Corners of the mouth should rise to the same height

Equal amounts of teeth should be visible on either side

Ask the patient to puff out their cheeks.

Both sides should puff equally and air should not leak from the mouth

SENSORY COMPARTMENT TESTING

Apply sugar, salt, or lemon juice on a cotton swab to the lateral aspect of each side of the tongue

Have the patient identify the taste

CN VII is responsible for taste sensation on anterior 2/3 of the tongue

Taste is often tested only when specific pathology of the facial nerve is suspected

DISORDERS IN CN VII & INTERPRETATION

CN 7 has a precise pattern of innervation, which has important clinical implications. o Right and Left Upper Motor Neurons (UMNs)

Each innervate both the right and left lower motor neurons (LMNs) that

Allow the forehead to move up and down o Right and Left Lower Motor Neurons (LMNs)

Control the muscles of the lower face Innervated by the UMN from the opposite side of the face

In the setting of CN VII dysfunction pattern of weakness or paralysis observed will differ on whether the UMN or LMN is affected

Figure 8. Innervation of CN VII - UMN and LMN

UMN Dysfunction o Occur with a central nervous event (eg. Stroke)

o Right CN VII UMN Dysfunction Patient is able to wrinkle their forehead on both sides of

their face

Because the Left CN VII UMN cross innervates the Right CN VII LMN that also controls the movement of the forehead

However, patient would be unable to effectively close their left eye or raise the left corner of their mouth

Because the Left CN VII LMN that innervates the face below the forehead is innervated by Right CN VII UMN (has dysfunction)

Figure 9. Right CN VII UMN Dysfunction. Note: a.)

preserved ability to wrinkle forehead; b.) left corner of mouth is slightly lower than right; c.) left

nasolabial fold is slightly less pronounced compared with right

LMN Dysfunction o Occur most commonly in Bells Palsy an idiopathic acute CN

VII peripheral nerve palsy

o Right CN VII LMN (Peripheral) Dysfunction Affects same side Patient would not be able to wrinkle their forehead (right

side) Patient cant close eyes (right side) Patient cant raise the corner of their mouth (right side) Left side function would be normal

Figure 10. Left CN VII LMN (Peripheral) Dysfunction. Note loss of: a.) forehead wrinkle; b.) ability to close

eye; c.) ability to raise corner of mouth; d.) decreased nasolabial fold prominence on left

Clue! Always check first if patient can wrinkle the forehead:

o If yes then it is not a LMN dysfunction o If no

- then it is a LMN dysfunction - the cranial nerve involved is on the same side. - eg. if patient cant wrinkle his forehead and has

weakness on the left side of the face, then it is a case left LMN dysfunction.

DISORDERS MANIFESTATIONS

Facial Weakness Flattening of the nasolabial fold Drooping of the lower eyelid

Peripheral Injury to CN 7 (Bells Palsy)

Affects both the upper and lower face

Central lesion affects mainly the lower face

Hyperacusis Loss of taste

Increased or decreased tearing

Unilateral Facial Paralysis Mouth droops on the paralyzed side when the patient smiles or

grimaces

QUIZ TIME! What cranial nerve is affected? Is this an upper or lower motor neuron dysfunction? Right or left?

Figure 10. A man with inability to wrinkle the area above the right eyebrow area and right facial weakness below eyebrow area.

Answers: Review yourself No. 1: Right CN III Review yourself No. 2: Right CN VII LMN dysfunction

CRANIAL NERVE VIII VESTIBULOCOCHLEAR NERVE

CN 8 carries sound impulses from the cochlea to the brain.

Prior to reaching the cochlea, the sound must first traverse the external canal and middle ear

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CRANIAL NERVES

ASSESSMENT

1. Stand behind the patient and ask them to close their eyes 2. Whisper a few words from just behind one ear. The patient should

be able to repeat these back accurately. Then perform the same test for the other ear.

3. Alternatively, place your fingers approximately 5 cm from one ear and rub them together. The patient should be able to hear the sound generated. Repeat for the other ear

4. These tests are rather crude. Precise quantification, generally necessary whenever there is a subjective decline in acuity, requires special equipment and training

5. The cause of subjective hearing loss can be assessed with bedside testing.

Hearing is broken into 2 phases:

1. Conductive Refers to the passage of sound from the outside to the level of

CN 8. This includes the transmission of sound through the external

canal and middle ear 2. Sensorineural Refers to the transmission of sound via CN 8 to the brain.

Identification of conductive (a much more common problem in the

general population) defects is determined as follows:

WEBER TEST

1. Grasp the 512 Hz tuning fork by the stem and strike it against the bony edge of your palm, generating a continuous tone. Alternatively you can get the fork to vibrate by "snapping" the ends between your thumb and index finger

2. Hold the stem against the patients skull, along an imaginary line that is equidistant from either ear.

3. The bones of the skull will carry the sound equally to both the R and L CN 8. Both CN 8s, in turn, will transmit the impulse to the brain

4. The patient should report whether the sound was heard equally in both ears or better on one side then the other (referred to as lateralizing to a side)

RINNE TEST

1. Grasp the 512 Hz tuning fork by the stem and strike it against the bony edge of your palm, generating a continuous tone.

2. Place the stem of the tuning fork on the mastoid bone, the bony prominence located immediately behind the lower part of the ear. The vibrations travel via the bones of the skull to CN 8, allowing the patient to hear the sound.

3. Ask the patient to inform you when they can no longer appreciate the sound. When this occurs, move the tuning fork such that the tines are placed right next to (but not touching) the opening of the ear. At this point, the patient should be able to again hear the sound. This is because air is a better conducting medium then bone.

Interpretation: o The above testing is reserved for those instances when a patient

complains of a deficit in hearing. o Thus, on the basis of history, there should be a complaint of

hearing decline in one or both ears.

Conductive Hearing Loss

The Weber test will lateralize (i.e. sound will be heard better) in the ear that has the subjective decline in hearing.

o Competing sounds from the outside cannot reach CN 8 via the external canal

o Sound generated by the vibrating tuning fork and traveling to CN 8 by means of bony conduction is better heard as it has no outside competition.

In the Rinne Test, bone conduction (BC) > air conduction (AC) o If there is a blockage in the passageway (e.g. wax) that

carries sound from the outside to CN 8, then sound will be better heard when it travels via the bones of the skull.

Sensorineural Hearing Loss

The Weber test will lateralize to the ear which does not have the subjective decline in hearing.

o This is because CN 8 is the final pathway through which sound is carried to the brain.

o Even though the bones of the skull will successfully transmit the sound to CN 8, it cannot then be carried to the brain due to the underlying nerve dysfunction.

Air conduction > bone conduction (normal).

Thus, regardless of the means (bone or air) by which the impulse gets to CN 8, there will still be a marked hearing decrement in the affected

ear. As AC is normally better then BC, this will still be the case.

Bates:

The whispered voice test is both sensitive (>90%) and specific (>80%) when assessing presence or absence of hearing loss.

Excess cerumen, otosclerosis, otitis media in conductive hearing loss; presbyacusis from aging, most commonly in sensorineural hearing loss

Vertigo with hearing loss and nystagmus in Meniere's disease

Hoarseness in vocal cord paralysis; nasal voice in paralysis of the palate Pharyngeal or palatal weakness The palate fails to rise with a bilaterallesion of the vagus nerve. In unilateral paralysis, one side of the palate fails to rise and, together with the uvula, is pulled toward the normal side

CRANIAL NERVES IX, X GLOSSOPHARYNGEAL AND VAGUS NERVE

These nerves are responsible for raising the soft palate of the mouth

and the gag reflex, a protective mechanism which prevents food or

liquid from traveling into the lungs. As both CNs contribute to these

functions, they are tested together.

IX GLOSSOPHARYNGEAL

CN IX is also responsible for taste originating on the posterior 1/3 of the

tongue.

X - VAGUS

CN X also provides parasympathetic innervation to the heart, though

this cannot be easily tested on physical examination.

Bates:

Listen to the voice o Is it hoarse?

Hoarseness suggests vocal cord paralysis o Does it have a nasal quality?

Paralysis of the palate Is there difficulty in swallowing?

Pharyngeal or palatal weakness

TESTING FOR ELEVATION OF THE SOFT PALATE

1. Ask the patient to open their mouth and say, ahhhh, causing the soft palate to rise upward.

2. Look at the uvula, a midline structure hanging down from the palate. o If the tongue obscures your view, take a tongue depressor and

gently push it down and out of the way. o The uvula should rise up straight and in the midline.

Normal Oropharynx

TESTING FOR GAG REFLEX

1. Ask the patient to widely open their mouth. a. If you are unable to see the posterior pharynx (i.e. the back of

their throat), gently push down with a tongue depressor. b. In some patients, the tongue depressor alone will elicit a gag.

In most others, additional stimulation is required. Take a cotton-tipped applicator and gently brush it against the posterior pharynx or uvula. This should generate a gag in most patients.

2. A small but measurable percent of the normal population has either a minimal or non-existent gag reflex. Presumably, they make use of other mechanisms to prevent aspiration.

Perform this test when there is reasonable suspicion that

pathology exists.

This would include two major clinical situations:

i. If you suspect that the patient has suffered acute dysfunction, most commonly in the setting of a stroke.

These patients may complain of cough when they swallow. They may suffer from recurrent pneumonia. Both of these

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CRANIAL NERVES

events are signs of aspiration of food contents into the passageways of the lungs. These patients may also have other cranial nerve abnormalities as lesions affecting CN 9 and 10 often affect CNs 11 and 12, which are anatomically nearby.

ii. Patients suffering from sudden decreased level of consciousness. In this setting, the absence of a gag might indicate that the patient is no longer able to reflexively protect their airway from aspiration. Strong consideration should be given to intubating the patient, providing them with a secure mechanical airway until their general condition improves.

BATES!

BILATERAL LESION of CN X palate fails to rise

UNILATERAL LESION of CN X one side of palate fails to rise and (with uvula) is pulled toward the NORMAL side

CRANIAL NERVE XI ACCESSORY NERVE

CN XI innervates the ff muscles:

Trapezius which permit shrugging of the shoulders

SCM which turns the head laterally

ASSESSMENT

Bates:

Look for atrophy or fasciculations (fine flickering irregular movements in small groups of muscle fibers) in the trapezius o Suggests peripheral nerve disorder

Compare one side with the other o Trapezius paralysis: The shoulder droops and the scapula

is displaced downward and laterally

1. Place your hands on top of either shoulder 2. Ask the patient to shrug while you provide resistance. Dysfunction

will cause weakness/absence of movement on the affected side. (Tests the trapezius)

3. Place your open left hand against the patients right cheek 4. Ask them to turn into your hand while you provide resistance. Then

repeat on the other side. (Tests the SCM)

The right Sternocleidomastoid muscle causes the head to turn to the left, and vice versa.

Bates:

Trapezius Weakness with Atrophy and Fasciculations Peripheral Nerve Disorder

Trapezius Paralysis shoulder droops and scapula is displaced downward and laterally

Supine Patient with BILATERAL weakness of Sternomastoids- presents with difficulty raising head of pillow

CRANIAL NERVE XII HYPOGLOSSAL NERVE

Each CN XII is responsible for tongue movement of of the tongue.

ASSESSMENT

1. Ask the patient to stick their tongue straight out of their mouth. 2. If there is any suggestion of deviation to one side/weakness, direct

them to push the tip of their tongue into either cheek while you provide counter pressure from the outside.

Or, alternatively,

1. Instruct the patient to stick out the tongue and then move it laterally against resistance.

Interpretation:

The tongue deviates to the side of the CN XII with lesion.

Kasi the tongues action is pushing.

For example, if the right CN 12 is dysfunctional, the tongue will deviate to the right.

The normally functioning left half will dominate as it no longer has opposition from the right. Similarly, the tongue would have limited or absent ability to resist against pressure applied from outside the left cheek.

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CRANIAL NERVES

CRANIAL NERVE INNERVATION PRIMARY FXN(S) TEST(S)

Olfactory Sensory Smell Identify odors

Optic Sensory Vision Visual acuity, fields, color, nerve head

Oculomotor Motor Upper lid elevation extraocular eye movement pupil constriction, accommodation

Physiologic "H" Near point response

Trochlear Motor Superior oblique muscle Physiologic "H"

Trigeminal

Motor Muscles of mastication Corneal reflex

Sensory Scalp, conjunctiva, teeth Clench jaw/palpate Light touch comparison

Abducens Motor Lateral rectus muscle Abduction, physiologic "H"

Facial

Motor Muscles of facial expression Smile, puff cheeks, wrinkle forehead, pry open closed lids

Sensory Taste-anterior two thirds of tongue

Vestibulocochlear Sensory Hearing and balance Rinne test for hearing Weber test for balance

Glossopharyngeal Motor Tongue and pharynx Gag reflex

Sensory Taste-posterior one third of tongue

Vagus

Motor Pharynx, tongue, larynx, thoracic and abdominal viscera

Gag reflex

Sensory Larynx, trachea, esophagus

Accessory Motor Sternomastoid and trapezius muscles Shrug, head turn against resistance

Hypoglossal Motor Muscles of tongue Tongue deviation REMEMBER IT! Oh Oh Oh! To Touch And Feel Vivacious Girls Vaginas Ah Heaven! :D

SING IT! Se-Se-Mo-Mo-Mi-Mo-Mi-Se-Mi-Mi-Mo-Mo

QUIZ TIME!!

Ang unang makapagsabi ng anime na kinabibilangan ng mga characters sa baba ay bibigyan ko ng chocnut sa Tuesday! :D