Cranial Nerves and Their Functions

Cranial Nerves Overview

I. Olfactory Nerve (CN I)

• Type: Sensory
• Function: Sense of smell
• Damage: Impaired sense of smell

II. Optic Nerve (CN II)

• Type: Sensory
• Function: Vision
• Damage: Blindness (complete or partial)

III. Oculomotor Nerve (CN III)

• Type: Motor
• Functions:
  • Opening eyelid
  • Eye movement
  • Focusing
  • Pupil constriction (Parasympathetic)
• Damage:
  • Drooping eyelid
  • Difficulty focusing
  • Eye drifts laterally
  • Dilated pupil (Parasympathetic)

IV. Trochlear Nerve (CN IV)

• Type: Motor
• Function: Rotate eye inferiomedially
• Damage: Eye points superiolaterally, leading to double vision

V. Trigeminal Nerve (CN V)

• Type: Both (Sensory & Motor)
• Sensory Functions:
  • Upper face
  • Eye
  • Mouth (touch, pain, temperature)
• Motor Functions:
  • Muscles of mastication (chewing)
• Damage:
  • Loss of facial sensation
  • Impaired ability to close mouth

VI. Abducens Nerve (CN VI)

• Type: Motor
• Function: Moves eye laterally
• Damage: Cannot move eye laterally

VII. Facial Nerve (CN VII)

• Type: Both (Sensory & Motor)
• Sensory Functions:
  • Taste in anterior 2/3 of tongue
• Motor Functions:
  • Muscles of facial expression (Somatic)
  • Salivation, tearing (Parasympathetic)
• Damage:
  • Sagging face muscles
  • Loss of taste (sweet)
  • Decreased tear production (Parasympathetic)