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Cranial Nerves

Cranial Nerves with Functions

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  1. Olfactory (I) → Smell (nose)
  2. Optic (II) → Vision (eyes)
  3. Oculomotor (III) → Eye movement, pupil constriction
  4. Trochlear (IV) → Eye movement (superior oblique muscle)
  5. Trigeminal (V) → Facial sensation (touch, pain, temperature) & chewing muscles
  6. Abducens (VI) → Eye movement (lateral rectus)
  7. Facial (VII) → Facial expressions & taste (anterior 2/3 of tongue)
  8. Vestibulocochlear (VIII) → Hearing & balance (ear)
  9. Glossopharyngeal (IX) → Taste (posterior 1/3 tongue), swallowing, gag reflex
  10. Vagus (X) → Parasympathetic control (heart, lungs, GI), voice, swallowing
  11. Accessory/Spinal Accessory (XI) → Neck & shoulder muscles (sternocleidomastoid, trapezius)
  12. Hypoglossal (XII) → Tongue movement

Eyes Movement:

  • SR – Superior Rectus
  • IR – Inferior Rectus
  • MR – Medial Rectus
  • LR – Lateral Rectus
  • SO – Superior Oblique
  • IO – Inferior Oblique
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III – Oculomotor

  • Muscles: Superior rectus, Inferior rectus, Medial rectus, Inferior oblique
  • Movements:
    • Upward (superior rectus)
    • Downward (inferior rectus)
    • Inward/adduction (medial rectus)
    • Up & outward rotation (inferior oblique)
  • Also controls pupil constriction and eyelid elevation (levator palpebrae).

IV – Trochlear

  • Muscle: Superior oblique
  • Movement: Down & inward (depression when eye is adducted; intorsion/rotation).

VI – Abducens

  • Muscle: Lateral rectus
  • Movement: Outward (abduction).