Anatomy & Histology · single question
A patient has a small lesion in the lower lip. What nerve innervates the lower lip?
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Correct answer: B. Mental nerve and inferior labial nerve (branches of mental nerve / CN V3)
- A. INCORRECT. The lingual nerve provides sensory innervation to the anterior two-thirds of the tongue and lingual gingiva. The buccal nerve innervates the buccal mucosa and skin over the cheek — neither innervates the lower lip.
- B. CORRECT. The lower lip is innervated by the mental nerve (a branch of the inferior alveolar nerve, itself a branch of CN V3/mandibular division of trigeminal nerve) and its terminal branch, the inferior labial nerve. These provide sensory innervation to the skin of the lower lip, chin, and labial gingiva of the mandibular incisors.
- C. INCORRECT. The infraorbital nerve (CN V2) innervates the upper lip, lower eyelid, lateral nose, and anterior cheek. It does not innervate the lower lip.
- D. INCORRECT. The greater auricular nerve (from cervical plexus, C2–C3) innervates the ear and parotid region skin. It does not contribute to lower lip innervation.
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