Cranial Nerves

Question 1

What are the 12 cranial nerves?

Answer 1

Olfactory, Optic, Oculomotor, Trochlear, Trigeminal, Abducent, Facial, Vestibulocochlear, Glossopharyngeal, Vagus, Accessory and Hypoglossal

Question 2

What does the glossopharyngeal nerve innervate?

Answer 2

Sensory - posterior tongue, tonsil and pharynx
Motor - pharyngeal musculature

Question 3

What does the vagus nerve innervate?

Answer 3

Motor - heart, lungs, bronchi, GI tract
Sensory - Heart, lungs, bronchi, trachea, larynx, pharynx, GI tract and external ear

Question 4

What does accessory nerve innervate?

Answer 4

SCM and trapezius muscle

Question 5

What are the special senses of cranial nerves?

Answer 5

Olfactory - CNI
Vision - CNII
Taste - VII, IX, X
Hearing - VIII

Question 6

What nerves cause ordinary sensation?

Answer 6

Mainly Vth - trigeminal
Ear - VII and IX

Question 7

What nerves control muscle activity?

Answer 7

Eye muscles - III, IV and VI
Mastication - V
Facial expression - VII
Larynx and pharynx - mainly X
SCM and trapezius - XI

Question 8

What nerve causes lacrimation?

Answer 8

Flow of tears - VII

Question 9

What nerves cause salivation?

Answer 9

Submandibular and sublingual - VII
Parotid gland - IX

Question 10

What nerve causes autonomic functions to organs in thorax and abdomen - parasympathetic?

Answer 10

Vagus - X

Question 11

How do we test CN I?

Answer 11

Smell kit
Can be unilateral or bilateral loss
Usually presents in history

Question 12

How do we test CN II?

Answer 12

Visual acuity, visual fields, pupillary reactions, fundoscopy and colour vision

Question 13

How do we test CN III, IV and VI?

Answer 13

Ptosis, pupillary reflex, eye movements (H formation)
Ask for diplopia

Question 14

How do we test CN V?

Answer 14

Sensation in ophthalmic, maxillary and mandibular divisions
Power of muscles of mastication, corneal reflex, and jaw jerk

Question 15

How do we test CN VII?

Answer 15

Muscles of facial expression, corneal reflex for efferent pathway and sense of taste

Question 16

How do we test CN VIII?

Answer 16

Hearing using Rinne’s and Weber’s tests
Vestibular function using Dix-Hallpike manoeuvre and Untenberger’s test

Question 17

How do we test CN IX and X?

Answer 17

Movement of the palate, gag reflex, quality of speech and quality of cough

Question 18

How do we test CN XI?

Answer 18

Head turning and shoulder shrugging

Question 19

How do we test CN XII?

Answer 19

Appearance, movement and power of the tongue

Question 20

What cranial nerves are involved in the pupillary light reflex?

Answer 20

Afferent - II
Efferent - III

Question 21

What cranial nerves are involved in the corneal reflex?

Answer 21

Afferent - V
Efferent - VII

Question 22

What cranial nerve is involved in the jaw jerk reflex?

Answer 22

Afferent and efferent - V

Question 23

What cranial nerves are involved in the gag reflex?

Answer 23

Afferent - IX
Efferent - X

Question 24

Where is the location of the cranial nerve nuclei?

Answer 24

III + IV - Midbrain
V, VI + VII - Pons
VIII - Pontomedullary junction
IX, X, XI + XII - Medulla

Question 25

What combination of cranial nerves can show superior orbital fissure affected?

Answer 25

III, IV and VI

Question 26

What combination of cranial nerves can show cerebellopontine angle affected?

Answer 26

V and VIII

Question 27

How can cranial nerves become damaged?

Answer 27

Within the brain - ischemia or tumour Crossing subarachnoid space - meningitis Outside of skull - Base of skull tumours arising in nasopharynx

Question 28

Describe optic neuritis

Answer 28

Inflammation of optic nerve - demyelination Monocular visual loss, pain on eye movement, reduced visual acuity + colour vision, optic disc can be swollen Often associated with MS

Question 29

What is the parasympathetic pupillary response?

Answer 29

Constriction of pupil Loss of this - results in fixed dilated pupil Ex. complete CN III palsy

Question 30

What is the sympathetic pupillary response?

Answer 30

Pupillary dilatation Damage anywhere within the sympathetic pathway can lead to constricted pupil

Question 31

What are come causes of dilated pupils?

Answer 31

Youth, dim lighting, anxiety, excitement, mydriatic eye drops, amphetamine, cocaine overdose, CN III palsy and brain death

Question 32

What are some causes of constricted pupils?

Answer 32

Old age, bright light, miotic eye drops, opiate overdose and Horner's syndrome

Question 33

What are some eye movement disorders?

Answer 33

Isolated CN III palsy, VI palsy, VI palsy Combination of above Supranuclear gaze palsy Nystagmus

Question 34

What are the 2 causes of isolated third nerve palsy?

Answer 34

Microvascular - diabetes, hypertension Compressive - posterior communicating artery aneurysm and raised ICP

Question 35

What are symptoms of microvascular and compressive third nerve palsy?

Answer 35

Painless and pupil spared - microvascular Painful (headache) and pupil affected - compressive

Question 36

What are some cause of isolated sixth nerve palsy?

Answer 36

Idiopathic, diabetes, meningitis, and raised ICP

Question 37

What are some causes for nystagmus?

Answer 37

Congenital, serious visual impairment, peripheral vestibular problem, central vestibular/ brainstem disease, cerebellar disease and toxins (alcohol and meds)

Question 38

Describe trigeminal neuralgia

Answer 38

Paroxysmal attacks of lancinating pain in face Triggers are chewing, speaking, cold air Middle age and older Caused by vascular loop which compresses CN V in posterior fossa

Question 39

What is the treatment for trigeminal neuralgia?

Answer 39

Medically - carbamazepine and other antiepileptic medication Surgical - if medication resistant

Question 40

Describe Bell's palsy

Answer 40

Idiopathic facial nerve palsy Unilateral facial weakness, LMN type, can have pain behind ear, eye closure, risk of corneal damage Treated with steroids

Question 41

What is the difference between UMN and LMN facial paralysis?

Answer 41

UMN - caused by stroke or tumour. Involves forehead LMN - caused by bell's palsy, lyme, sarcoid. No involvement of forehead

Question 42

Describe vestibular neuronitis

Answer 42

Sudden onset disabling vertigo Vomiting Gradual recovery Cause is uncertain - viral

Question 43

What is bulbar and pseudobulbar palsy?

Answer 43

Bulbar - LMN Pseudobulbar - UPM

Question 44

Describe pseudobulbar palsy

Answer 44

Bilateral UMN lesions - internal capsule, MND Symptoms - dysarthria, dysphonia, dysphagia, spastic immobile tongue, brisk jaw jerk and gag reflex

Question 45

Describe bulbar palsy

Answer 45

Bilateral LMN lesions affecting IX - XII - MND, polio, tumour, vascular lesion of medulla and syphilis Symptoms - wasting, dysarthria, dysphagia, dysphonia