Tongue Movement

• The hypoglossal nerve, CN XII provides motor innervation to the tongue.
• Normally, a horse resists the tongue being retracted from the mouth.
  • The horse will quickly return the tongue after it is pulled out to the side.
• Horses with hypoglossal weakness appear differently.
  • The tongue may protrude from the mouth.
  • Chronic unilateral hypoglossal lesions may result in unilateral tongue atrophy.
  • Bilateral hypoglossal lesions may result in difficulty prehending food.
• Horses with cerebral dysfunction may have signs corresponding to tongue weakness.
  • However, tongue atrophy is not present in these animals.