1. OCULAR MOTOR NERVE PALSIES
1. Third nerve
2. Fourth nerve
3. Sixth nerve

2. Anatomy of third nerve Oculomotor nucleus Pituitary gland Red nucleus
Carotid artery
Cavernous sinus
Pons
III nerve
Post cerebral artery
Clivus
Basilar artery

3. Applied anatomy of pupillomotor nerve fibres
Blood vessels on pia mater supply surface
of the nerve including pupillary
fibres ( damaged by
compressive lesions )
Vasa nervorum supply part
of nerve but not pupillary
fibres ( damaged by medical
lesions )
Pupillary fibres lie dorsal and peripheral

4. Signs of right third nerve palsy
Ptosis, mydriasis and cycloplegia
Abduction in primary position
Normal abduction
Intorsion on attempted
downgaze
Limited adduction
Limited elevation
Limited depression

5. Hess chart of right third nerve palsy
Contraction of right chart and expansion of left
Right chart - underactions of all muscles except lateral rectus and superior oblique
Left chart - overactions of all muscles except medial rectus and inferior oblique

6. Important causes of isolated third nerve palsy
Idiopathic - about 25%
Vascular disease - hypertension, diabetes
Trauma
Posterior communicating aneurysm
Extradural
haematoma
Aneurysm
Chiasm
Midbrain
pushed
across
Edge of
tentorium
Prolapsing
temporal
lobe
Posterior cerebral
artery
Third nerve

7. Anatomy of fourth nerve
Only cranial nerve to emerge dorsally
Crossed cranial nerve
Very long and slender
Internal carotid artery
Postr. communicating
artery
III VI
Postr.cerebral artery
Supr.cerebellar artery
Basilar artery IV

8. Signs of right fourth nerve palsy
Right hyperdeviation in primary
position when left eye fixating
Excyclotorsion
Right underaction on depression
in adduction
Vertical diplopia
Right overaction on left gaze

9. Positive Bielschowsky test in right fourth nerve palsy
Increase in right
hyperdeviation on ipsilateral
head tilt
Absence of right
hyperdeviation on
contralateral head tilt

10. Hess chart of right fourth nerve palsy
No significant difference in chart size
Upward deviation of right fixation spot on inner chart (hypertropia)
Downward deviation of left fixation spot on inner chart
Right chart - underaction of superior oblique and overaction of inferior oblique
Left chart - overaction of inferior rectus and underaction of superior rectus

11. Anatomy of sixth nerve Basilar artery Pituitary gland Medial lemniscus
Carotid artery
4th ventricle
Cavernous sinus
Petroclinoid
ligament
Clivus
Vestibular
nucleus
VI nerve
Pyramidal tract

12. Recent right sixth nerve palsy
Right esotropia in primary position due to
unopposed action of right medial rectus
Marked limitation of right abduction due to
right lateral rectus weakness

13. Hess chart of recent right sixth nerve palsy
Contraction of right chart and expansion of left
Right chart - marked underaction of lateral rectus and mild overaction of medial rectus
Left chart - marked overaction of medial rectus

14. Old right sixth nerve palsy
Straight in primary position due to partial
recovery
Limitation of right abduction and
horizontal diplopia
Normal right adduction

15. Important causes of isolated sixth nerve palsy
Vascular - hypertension, diabetes
Raised intracranial pressure
Acoustic neuroma
Dilated
ventricles
Petrous
tip
Brainstem pushed downwards