Eye Movements (3rd, 4th, 6th)

Question 1

Which muscles and cranial nerves are involved at each point of ‘H’ when testing the eye movements?

Answer 1

Patient right: R LR (6), L MR (3)
Right up: R SR (3), L IO (3)
Right down: R IR (3), L SO (4)

Patient left: L LR (6), R MR (3)
Left up: L SR (3), R IO (3)
Left down: L IR (3), R SO (4)

Question 2

Oculomotor Nerve: Findings of complete 3rd nerve palsy

Answer 2

Ptosis
Dilated unreactive pupil
Down and out

Question 3

Oculomotor Nerve: Findings of partial 3rd nerve palsy

Answer 3

Ptosis
Normal pupil
Down and out

Question 4

Trochlear Nerve: Findings of 4th Nerve palsy

Answer 4

Head tilt away from SO affected
Double vision when looking down

Question 5

Abducens Nerve: Findings of 6th Nerve palsy

Answer 5

Convergent squint
Horizontal diplopia on abduction of LR

Question 6

Internuclear Ophthalmoplegia: what is it? what causes it? what do you find on examination?

Answer 6

Disruption of Conjugate gaze - medial longitudinal fasicules joins R CN 3 and L CN 6; and L CN3 and R CN6.
Cause: MS
Findings: R eye unable to adduct is R MFL affected; L eye unable to adduct is L MFL affected

Question 7

Causes of 6th nerve palsy

Answer 7

False localising: raised intracranial pressure! e.g. subarachnoid haemorrhage
Lesion in the pons - stroke, MS, SOL (expect 7th nerve palsy)
CPA if other nerves also affected
Cavernous sinus thrombosis
Internal artery dissection
Damage to the internal auditory meatus: cholesteatoma, mastoiditis

Inflammatory: Sarcoid, Lupus
Infection: Syphilis, TB, Lyme

Question 8

Pathway of 6th cranial nerve

Answer 8

Pons
Subarachnoid space
Cavernous sinus
Medial to internal carotid
Superior orbital fissure
Orbit Lateral rectus

Question 9

Pathway of cranial nerve 3

Answer 9

Midbrain
Cavernous sinus
Superior orbital fissure
Occular muscles
Eyelid
Parasympathetic pupil

Question 10

Pathway of cranial nerve 4

Answer 10

Midbrain
Cavernous sinus
Superior orbital fissure
Superior oblique

Question 11

Pathway of cranial nerve 6

Answer 11

Pons
Cavernous sinus
Superior orbital fissure
Lateral rectus