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Oculomotor nerve
The oculomotor nerve has somatic and visceral motor components. The somatic component supplies four extraocular muscles and the levator palpebrae superioris muscle. The visceral component provides parasympathetic innervation to the constrictor pupillae and ciliary muscles. The oculomotor nerve originates in the midbrain, passes through the cavernous sinus, and enters the orbit through the superior orbital fissure to innervate the extraocular muscles. Damage to the oculomotor nerve can cause an oculomotor nerve palsy and result in drooping of the eyelid and eye muscle weakness.
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Oculomotor nerve
- 1. Oculomotor nerve Dr /Hytham Nafady
- 3. Introduction Oculomotor nerve consistsof 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.
- 6. From To Uncrossed fibers ipsilateral oculomotor nucleus Medial rectus. Inferiorrectus. 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.
- 8. •Medial rectus •Inferior rectus •Levatorpalpebrae superioris •Superior rectus •Inferior oblique
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- 10. Origin Oculomotor nucleus: • Tegmentumof midbrain at the level of superior colliculus. • Ventral to the peri-aqueductal grey matter. • It is column shaped nucleus & consists of complex subnuclei.
- 12. 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.
- 13. Central segment The centralsegment courses ventrally • From the midbrain tegmentum, • through the red nucleus, • to emerge from the medial aspect of the cerebral peduncle.
- 16. Cisternal segment • Courseventrolaterally through the interpeduncular cistern between the PCA & SCA.
- 17. Cisternal segment ofoculomotor nerve Cn 3 Interpeduncular cistern
- 18. Cisternal segment ofoculomotor nerve BA Cn 3SCA PCA
- 19. Cisternal segment ofoculomotor nerve
- 20. Cisternal segment ofoculomotor nerve
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- 22. Cavernous segment • Theoculomotor 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).
- 24. 4 5 O 6 3 5mx Oculomotor cistern
- 25. Orbital segment • Theoculomotor 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.
- 26. Superior orbital fissure& annular ring of Zinn
- 28. Cn 3 i Cn3 s Cn 6 Cn 4
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- 32. Oculomotor nerve palsy withpupillary sparing (medical 3rd Cn palsy) • DM. • Hypertension.
- 33. Oculomotor nerve palsy withoutpupillary sparing • Nucleus. • Central segment. • Cisternal segment. • Cavernous segment. • Orbital segment.
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- 46. Cavernous sinus lesionwith 3rd cranial nerve palsy
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- 48. Right carotid cavernousfistula with 3rd & 4th Cn palsy
- 49. Orbital segment • Lesionsof the orbital apex cause 3rd , 4th and 6th cranial nerve palsies
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