The document summarizes key details about the occulomotor nerve (CN III) including its anatomy, nuclei, course through the brain and orbit, functions of the muscles it innervates, and causes of occulomotor nerve palsy. The occulomotor nerve is a purely motor cranial nerve that controls four extraocular muscles and pupil constriction/accommodation. It can be affected at different levels from supranuclear to intraorbital portions. Lesions are diagnosed based on the specific muscles and eye movements involved.

1. OCCULOMOTOR
NERVE PALSY
DR ANSHUMALEE PATEL

2. Occulomotor nerve
• Entirely motor
• Somatic efferent - moves eyeball
• Viceral efferent - accomodation and miosis
• Somatic afferent - proprioception

3. Nucleus = Motor + EW nucleus
• Midbrain - level of superior
colliculus
• Venteromedial gray matter
surrounding aqueduct
• Longitudinal column - 10 mm
• Above - floor of 3rd ventricle
• Below - trochlear nerve
nucleus

4. Main motor nucleus
• Dorsolateral - IR
• Intermediate - IO
• Venteromedian - MR
• Paramedian - C/L SR
• Caudal central - B/L LPS

5. Edinger Westphal nucleus
• Preganglionic parasympathetic
• Cranial part - Light reflex
• Caudal part - Accomodation reflex

6. Course
• Fascicular part
• Basilar part
• Intracavernous part
• Intraorbital part

7. Fasciular part
Pass through
• Red nucleus
• Medial part of cerebral
peduncle

8. Basilar part
• Lateral root & Medial root unite
• B/W Superior Cerebellar Artery and Posterior
Cerebral Artery

9. Intracavernous part
• Enters posteriorly
through roof
• Lies above trochlear
nerve
• Anteriorly - divides into
superior and inferior
division

10. Intraorbital part

11. Ciliary ganglion
• Located near
the apex of
orbit - b/w
optic nerve and
LR muscle

12. Roots
Sensory
Parasympathetic
Sympathetic
Branches
15-20 short
ciliary nerves
• Sensory plexus
after piercing
sclera

13. Cross-section of the nerve

14. Occulomotor Nerve Palsy
• Ptosis
• Down and out eyeball
• Intortion
• Fixed dilated pupil
• Loss of accomodation
• Crossed diplopia

15. Muscles paralysed

18. Supranuclear lesions
• Cerebral cortex is involved
• Conjugate paresis - both eyes affected equally
• Relative position of eyes maintained - no diplopia

19. Nuclear lesions
• 3rd + 4th nerve nucleus = I/L sparing of elevation +
C/L weakness of elevation
• Medial Longitudinal Fasciculus = WEBINO syndrome
(adduction defect)
• Pure third nerve nuclear lesion - uncommon
Causes: Vascular, tumor, demylinating disorders

20. Lesions of fascicular part
• Benedikt syndrome - I/L 3rd N palsy + C/L tremors &
jerky movements
• Weber syndrome - I/L 3rd N palsy + C/L hemiplegia &
UMN 7th N palsy
• Nothnagel syndrome - I/L or B/L 3rd N palsy +
cerebellar ataxia
• Claude syndrome - Benedict + Nothnagel

21. Lesions of basilar part
Frequently cause isolated 3rd N palsy
• Aneurysm of posterior cerebral artery - pupil
involving
• Extradural hematoma - pupil involving
• Diabetes - pupil sparing

22. Lesions of intracavernous part
Frequently involves 3, 4, 6 nerves
• Pitutary apoplexy
• Meningioma
• Carotico-cavernous fistula
• Tolosa Hunt syndrome

23. Lesions of intraorbital part
• Trauma to orbital bones
• Vascular lesions
• Orbital tumors

24. Pupillomotor fibres
• Superomedian
• Blood supply - pial
vessels
• Rest of the nerve - vasa
nervorum

26. Pupil sparing in DM and HTN?
DM and Hypertension
Microangiopathy of vasa nervorum
Pupil sparing 3rd N palsy

27. Investigations
• RBS
• BP
• Lipid profile
• CBC with ESR
• Xray skull - r/o cavernous lesions
• MRI
• LP

28. Treatment
• Wait and watch
• Follow-up weekly for pupil sparing type
• Vitamin B complexx
• Steroid course
• Surgical measures