Cranial Nerves

Question 1

After leaving the brain stem where do the cranial nerves arising from the medulla enter?

Answer 1

Carotid sheath

Question 2

Which CNs arise from the midbrain pontine junction and the pontine-Medullary junction?

Which CN originates anterior to the olive of the medulla?

Answer 2

MB-PJ
- III

PMJ

• VI
• VII
• VIII

Hypoglossal (XII)

Question 3

Why can a tumour at the base of the frontal lobes lead to anosmia?

Answer 3

Impingement of CN I

Question 4

What does the brainstem communicate with the optic tract via?

Answer 4

Superior colliculus

Question 5

You shine light of left eye and only see a consensual light reflex.

Where is the lesion?

Answer 5

Left occulomotor nerve

Question 6

Anuerysm of what artery can compress on CNIII?

Where else is it vulnerable to compression?

In a vascular problem secondary to hypertension or diabetes, what is unique about presentation?

Answer 6

Posterior communicating artery

Tentorium cerebelli and temporal lobe - raised ICP causing uncal herniation.
Cavernous sinus thrombosis

Pupil sparing

Question 7

What can be noticed about patients head in trochlear nerve palsy? Why?

Answer 7

Tilted away from the side of the lesion. Minimise diplopia

Question 8

Give 2 conditions that can affect the trigeminal nerve.

Answer 8

Trigeminal neuralgia

Shingles

Question 9

What are the 3 branches of the Vc?

Answer 9

Inferior alveolar
Lingual
Auriculotemporal

Question 10

Why is CN VI more vulnerable to raised ICP?

Answer 10

Runs on the under surface of the pons before making a sharp turn as it heads towards the cavernous sinus

Question 11

Which nucleus do the autonomic fibres to salivary, lacrimal, nasal mucosal and palate glands originate (parasympathetics)?

Answer 11

Superior salivatory nucleus

Question 12

What ganglion does the greater petrosal nerve synapse in?

Answer 12

Pterygopalatine

Question 13

What are the afferent and efferent limbs of the corneal reflex?

Answer 13

Va

CNVII

Question 14

Name 3 important symptoms that could be associated with CNVII palsy

Answer 14

Hyperacusis
Dry eyes
Dusguesia

Question 15

What is an acoustic neuroma?

Why is facial weakness seen?

Symptoms?

Answer 15

Benign tumour of the Schwann cells surrounding the vestibular component of CN VIII

Facial nerve runs through IAM also in close proximity

Unilateral sensorineural hearing loss
Vertigo
Tinnitus
Numbness or pain down half of face

Question 16

Give general sensory special sensory, autonomic and motor functions of glossopharyngeal.

Answer 16

General sensory

• Palatine tonsils and oropharynx
• Middle ear and inner membrane
• Carotid body and sinus
• Posterior 1/3 tongue

Special sensory
- Posterior 1/3 tongue

Autonomic
- Parasympathetics to parotid gland

Motor
- Stylopharyngeus

Question 17

Give general sensory functions of the vagus nerve.

Answer 17

Laryngo pharynx and larynx
Tympanic membrane (external surgical) 
Posterior external ear

Question 18

How can you test for accessory nerve damage?

Which anatomical region does it run through?

Answer 18

Shrug shoulders against resistance or turn head against resistance

Posterior triangle posterolaterally

Question 19

Describe the route of the hypoglossal nerve.

What is its function?

Answer 19

Originates from the medulla anterior to the Olive and exits the cranium via the hypoglossal canal

It then runs medial to the angle of mandible and crosses the internal and external carotid arteries in the neck.

Tongue muscle innervation except palatoglossus

Question 20

In which nerve palsy will you diplopia which worsens of downward gaze?

Answer 20

Trochlear