Cranial nerve Examination

Question 1

What are the cranial nerves

Answer 1

12 pairs of nerves that emerge from brainstem and supply head and neck

sensory, motor and parasympathetic activity

Numbered 1-12

Question 2

CN abnormalities

Answer 2

Cranial nerve abnormalities may arise from lesions affecting the;

• communicating pathways to and from the cortex, cerebellum and other parts of the brain stem
• nerve nucleus
• nerve
• neuromuscular junction disorders
• Muscle

Question 3

Mnemonic for cranial nerves

Answer 3

Oh oh oh to touch and feel Virgin girls vagina and hymen

some say marry money but my brother says big brains matter most

Question 4

Olfactory

Answer 4

Sensory
smell
tract: olfactory cells of nasal mucosa –> olfactory bulbs –> pyriform cortex

Question 5

Optic nerve

Answer 5

Sensory
Vision
Tract: retinal ganglion cells –> optic chasm –> thalamus –> primary visual cortex in occipital lobe

Question 6

Muscles of the eye

Answer 6

Superior, inferior, medial and lateral rectus muscles

superior and inferior oblique

Question 7

Which cranial nerves innervate the eye muscles

Answer 7

Oculomotor, trochlear Abducens

Question 8

Oculomotor innerveates which muscles

Answer 8

all apart from lateral rectus and superior oblique

Question 9

Oculomotor

Answer 9

Motor function - innervates muscles and upper eyelet

parasympathetic function - constrict the pupils

Question 10

3rd nerve palsy

Answer 10

lateral rectus - laterally
superior oblique - down

Down and out + ptosis (parasympathetic innervation)

Question 11

Medical 3rd nerve palsy

Answer 11

pupil sparing

microvascular change on uncles or 3rd nerve pathway

Question 12

Surgical 3rd nerve palsy

Answer 12

pupillary dilation

parasympathetic fibres run on outside of oculomotor nerves

something that presses on the nerve ( causes the pupil to dilate)

Question 13

Trochlear nerve innervates

Answer 13

Superior oblique muscles

Question 14

Trochlear nerve

Answer 14

motor
moves the eyeball
nucleus location: midbrain

depresses the adducted eye and intorts the abducted eye

longest intracranial course are II and IV are only nerves to decussate to contralateral side

Question 15

Trochlear nerve lesions (4th nerve palsy)

Answer 15

Double vision when eye looking down (superior oblique moves the eye down)

When looking down at the paper or looking down the stairs

Question 16

abducens Nerve

Answer 16

motor
eyeball movement
nucleus: pons
Structure innervated : lateral rectus

Question 17

6th nerve palsy

Answer 17

horizontal double vision that is corrected in the primary position

Question 18

Causes of 6th nerve palsy

Answer 18

Vasculitis ( DM and HTN) 
Raised ICP (due to turning  junction)

Question 19

Causes of 4th nerve palsy

Answer 19

• vasculitis (HTN and DM)
• tumour
• trauma
• congenital

superior oblique

Question 20

3rd nerve palsy causes

Answer 20

Vasculitis (HTN and DM)

Aneurysm (berry aneurysm of circle of wills)

Question 21

Internuclear ophthalmoplegia

Answer 21

disorder of conjugate gaze
-failure of adduction of affected eye with nystagmus on lateral gaze in contralateral eye

Can be unilateral or bilateral
Results from lesion of medial longitudinal fasiculus (connects 3rd and 6th nerve nuclei)

Commonly seen in multiple sclerosis

Question 22

Horner syndrome

Answer 22

consists of:

• ptosis (drooping of the eyelid)
• miosis (constriction of the pupil)
• enopthlamosis (posterior displacement of the eyeball shruken)
• anhidorsis (not able to sweat properly)

From ipsilateral disruption of cervical/thoracic sympathetic chain

Question 23

Trigeminal nerve

Answer 23

sensory input from face
nucleus: Pons and medulla
structure innervated: face (ophthalmic, mandibular and maxillary division) and touch pain pressureto anterior 2/3rds of the tongue

Motor 
Mastication 
nucleus location: pons 
Structure innervated: 
Muscles of mastication (master, temporalis, medial and lateral pterygoids

Question 24

Herpes zoster opthalmicus

Answer 24

pain may priced vesicles 
lifetime risk 1% 
V2/v3 rarely affected 
elderly and immunocompromised 
treated with oral acyclovir

Question 25

Facial nerve

Answer 25

Motor
nucleus location: Pons
Function: muscles of facial expression

Sensory 
nucleus location: medulla 
Function: 
Taste 
structure innervated: anterior 2/3rd tongue 

parasympathetic
nucleus location: Medulla
Function: salivation and lacrimation
Structure innervated: salivary and lacrimal glands

Question 26

Lower facial weakness

Answer 26

both upper and lower

Question 27

Upper facial weakness

Answer 27

Upper part has dual innervation therefore only lower affected

Question 28

Corneal reflex

Answer 28

combines facial sensation and facial power

lightly touch cornea with cotton wool
-afferent - V
-efferent -VII
Test of pontine function

Question 29

Vestibulocochlear nerve

Answer 29

Sensory
balance
pons and medulla
structure innervated: nerve endings within semi-circular canals –> cerebellum and spinal cord

Sensory
hearing
nucleus: pons and medulla
Structure innervated: cochlear–> auditory cortex in the temporal lobes

Question 30

Glossopharyngeal

Answer 30

t