Which nerve, when anesthetized, is associated with numbness of the anterior two-thirds of the tongue?

• A. Lingual Nerve
• B. Glossopharyngeal Nerve
• C. Hypoglossal Nerve
• D. Inferior Alveolar Nerve

Answer: (A)

The sensation to the anterior two-thirds of the tongue is carried by the lingual nerve, a branch of the mandibular division of the trigeminal nerve. When this nerve is anesthetized, general sensation from that portion of the tongue is lost, producing numbness there. Taste fibers for the same region travel with the chorda tympani (a branch of the facial nerve) and join the lingual nerve, so a lingual nerve block can also affect taste in that area.

In contrast, the glossopharyngeal nerve supplies the posterior one-third of the tongue; the hypoglossal nerve is motor to the tongue muscles; and the inferior alveolar nerve mainly serves the lower teeth and surrounding tissues.