Anatomy & Histology · single question
Which of the following nerves provides motor innervation to the tongue?
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Correct answer: A. CN X and CN XII
Almost all tongue muscles receive motor innervation from the hypoglossal nerve (CN XII). The ONE exception is the palatoglossus muscle, which is innervated by the vagus nerve (CN X) via the pharyngeal plexus. Therefore, motor innervation to the tongue involves CN X (for palatoglossus) and CN XII (for all other intrinsic and extrinsic tongue muscles).
- A. CORRECT. CN X (vagus) innervates the palatoglossus (the only tongue muscle NOT innervated by CN XII), and CN XII (hypoglossal) innervates all other tongue muscles.
- B. INCORRECT. CN IX (glossopharyngeal) provides taste and sensation to the posterior 1/3 of the tongue and motor to the stylopharyngeus — not general tongue motor innervation.
- C. INCORRECT. CN V3 (mandibular branch of trigeminal) provides general sensation to the anterior 2/3 of the tongue and motor innervation to muscles of mastication — not tongue muscles.
- D. INCORRECT. CN VII (facial) provides taste to anterior 2/3 of the tongue via the chorda tympani and motor innervation to facial muscles of expression — not tongue muscles.
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