The nerve in the lower lip is the mental nerve.
The mental nerve is a sensory branch of the inferior alveolar nerve, which itself is a branch of the mandibular division (V3) of the trigeminal nerve (cranial nerve V). It emerges from the mental foramen, a small opening on the anterior surface of the mandible (lower jaw bone).
Here's a breakdown:
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Trigeminal Nerve (CN V): This is the fifth cranial nerve and is responsible for sensation in the face and motor functions such as chewing.
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Mandibular Division (V3): One of the three major divisions of the trigeminal nerve. It provides sensory innervation to the lower face (including the lower lip and chin) and motor innervation to the muscles of mastication (chewing).
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Inferior Alveolar Nerve: A branch of the mandibular division (V3). It travels through the mandible, providing sensation to the lower teeth.
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Mental Nerve: The terminal branch of the inferior alveolar nerve. It emerges from the mental foramen and provides sensation to:
- Skin of the lower lip
- Skin of the chin
- Labial mucosa (inner lining) of the lower lip
- Gingiva (gums) in the region of the incisors and canine teeth
Damage to the mental nerve (e.g., during dental procedures, facial trauma, or surgery) can result in numbness, tingling, or pain in the lower lip and chin. This condition is called mental nerve neuropathy.
