Cranial Nerves Functional Overview

Vestibulocochlear (VIII) Nerve Functions

• Sensory Function
  • Responsible for hearing and balance.
  • DAMAGE: Can result in symptoms like deafness, dizziness, nausea, and nystagmus.

Glossopharyngeal (IX) Nerve Functions

• Sensory Functions
  • Involved in sensation of the tongue and pharynx, including touch, taste, pressure, and pain.
• Motor Functions
  • Controls swallowing and gag reflex.
  • Parasympathetic Role: Salivation and regulation of blood pressure.
  • DAMAGE: May lead to impaired swallowing and loss of taste, primarily for sour flavors.

Vagus (X) Nerve Functions

• Sensory Functions
  • Provides sensory input from the gastrointestinal tract and sensation of fullness, hunger, GI discomfort.
• Motor Functions
  • Responsible for swallowing, gastrointestinal motility, and speech.
  • Parasympathetic Role: Slows heart rate.
  • DAMAGE: Can lead to inability to swallow, hoarse voice, or severe consequences if both vagal nerves are damaged (potentially fatal).

Accessory (XI) Nerve Functions

• Motor Functions
  • Involved in head, neck, and shoulder movements, specifically muscles such as sternocleidomastoid and trapezius.
  • DAMAGE: Causes inability to shrug shoulders or to turn head away from the injured side.

Hypoglossal (XII) Nerve Functions

• Motor Functions
  • Controls tongue movements crucial for swallowing and speech.
  • DAMAGE: Can lead to difficulties in speech and swallowing.
  • Bilateral Damage: Causes inability to protrude tongue.
  • Unilateral Damage: Results in deviation of the tongue toward the injury side.

Summary of Functions and Damage Effects

• VIII - Vestibulocochlear: Hearing and balance; damage leads to deafness, dizziness.
• IX - Glossopharyngeal: Sensation and motor in tongue/pharynx; damage can impair swallowing and taste.
• X - Vagus: Gastrointestinal functions and heart rate; damage may cause severe swallowing issues.
• XI - Accessory: Shoulder and neck movement; damage affects movements of these areas.
• XII - Hypoglossal: Tongue function; damage can significantly affect swallowing and speech abilities.