Oculomotor nerve

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Oculomotor nerve

  1. 1. Oculomotor nerve Dr / Hytham Nafady
  2. 2. Introduction Oculomotor nerve consists of two components with distinct functions: Somatic motor (general somatic efferent) Supplies 4 of the 6 extraocular muscles of the eye and the levator palpebrae superioris muscle of the upper eyelid. Visceral motor (general visceral efferent) Parasympathetic innervation of the constrictor pupillae and ciliary muscles.
  3. 3. From To Uncrossed fibers ipsilateral oculomotor nucleus Medial rectus. Inferior rectus. Inferior oblique. Crossed fibers Contralateral oculomotor nucleus Superior rectus. Crossed and uncrossed fibers Both oculomotor nuclei Levator palpebrae superioris muscle. Uncrossed para- sympathetic fibers Ipsilateral Edinger Westphal nucleus Constrictor pupliae muscle. Ciliary muscle.
  4. 4. •Medial rectus •Inferior rectus •Levator palpebrae superioris •Superior rectus •Inferior oblique
  5. 5. Oculomotor nerve anatomy
  6. 6. Origin Oculomotor nucleus: • Tegmentum of midbrain at the level of superior colliculus. • Ventral to the peri-aqueductal grey matter. • It is column shaped nucleus & consists of complex subnuclei.
  7. 7. Edinger Westphal nucleus: • The Edinger Westphal nucleus form the parasympathetic general visceral efferent (GVE) component of the nuclear complex. • It is located medial to the rostral end of the oculomotor nucleus.
  8. 8. Central segment The central segment courses ventrally • From the midbrain tegmentum, • through the red nucleus, • to emerge from the medial aspect of the cerebral peduncle.
  9. 9. Cisternal segment • Course ventrolaterally through the interpeduncular cistern between the PCA & SCA.
  10. 10. Cisternal segment of oculomotor nerve Cn 3 Interpeduncular cistern
  11. 11. Cisternal segment of oculomotor nerve BA Cn 3SCA PCA
  12. 12. Cisternal segment of oculomotor nerve
  13. 13. Cisternal segment of oculomotor nerve
  14. 14. Cisternal segment ICA
  15. 15. Cavernous segment • The oculomotor nerve enters the cavernous sinus superior to the petro-clinoid ligament and inferior to the inter-clinoid ligament. • The cavernous segment of the oculomotor nerve course through the lateral wall of the cavernous sinus superiorly. • It is surrounded by CSF dural cuff (oculomotor cistern).
  16. 16. 4 5 O 6 3 5 mx Oculomotor cistern
  17. 17. Orbital segment • The oculomotor nerve enters the orbit through the superior orbital fissure within the annular ring or Zinn. • It divides into superior and inferior divisions. • The superior division supplies the contralateral superior rectus & levator palpebrae superioris muscles bilaterally. • The inferior divison supply the ipsilateral inferior & medial recti & inferior oblique muscles.
  18. 18. Superior orbital fissure & annular ring of Zinn
  19. 19. Cn 3 i Cn 3 s Cn 6 Cn 4
  20. 20. Oculomotor palsy
  21. 21. Oculomotor nerve palsy with pupillary sparing (medical 3rd Cn palsy) • DM. • Hypertension.
  22. 22. Oculomotor nerve palsy without pupillary sparing • Nucleus. • Central segment. • Cisternal segment. • Cavernous segment. • Orbital segment.
  23. 23. Oculomotor nucleus
  24. 24. Cisternal segment
  25. 25. Cisternal segment
  26. 26. PCoA aneurysm
  27. 27. Lymphoma
  28. 28. Lymphoma
  29. 29. Cavernous segment
  30. 30. Cavernous sinus lesion with 3rd cranial nerve palsy
  31. 31. Schwannoma 3
  32. 32. Right carotid cavernous fistula with 3rd & 4th Cn palsy
  33. 33. Orbital segment • Lesions of the orbital apex cause 3rd , 4th and 6th cranial nerve palsies
  34. 34. Tolosa hunt syndrome
  35. 35. Tolosa Hunt syndrome ophthalmoplegia 3 3 3 4 6
  36. 36. Testing accomdation reflex

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