Anatomy & Histology · single question
When a tongue deviates to the RIGHT upon protrusion, which nerve/muscle is affected?
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Correct answer: D. Right hypoglossal nerve (right genioglossus paralyzed)
Upon protrusion, the tongue deviates toward the side of the lesion. If the tongue deviates to the RIGHT, the right hypoglossal nerve (CN XII) is affected — because the right genioglossus (which normally pushes the tongue to the left) is paralyzed. The left genioglossus continues to function, pushing the tongue to the right (affected side). Remember: tongue goes toward the bad side.
- A. ❌ Left hypoglossal nerve damage would cause the tongue to deviate LEFT (left genioglossus paralyzed, right pushes it left).
- B. ❌ The facial nerve does not innervate the tongue muscles (except taste on the anterior 2/3 via chorda tympani).
- C. ❌ The vagus nerve does not innervate tongue muscles — it innervates pharyngeal, palatal, and laryngeal muscles.
- D. ✅ CORRECT – Right hypoglossal nerve damage paralyzes the right genioglossus; the intact left genioglossus pushes the tongue to the right (toward the damaged side).
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