Which nerve, when anesthetized, causes ongoing numbness of the anterior two-thirds of the tongue?

Which nerve, when anesthetized, causes ongoing 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 main concept being tested is which nerve provides the sensory innervation to the front part of the tongue. The lingual nerve, a branch of the mandibular division of the trigeminal nerve, carries general sensation from the anterior two-thirds of the tongue. When this nerve is anesthetized, numbness occurs in that region. In addition, taste fibers from the anterior two-thirds travel with the lingual nerve via the chorda tympani, so anesthesia there can also affect taste in that area. The glossopharyngeal nerve supplies the posterior third of the tongue, the hypoglossal nerve is motor to the tongue muscles, and the inferior alveolar nerve supplies the lower teeth and surrounding areas, not the tongue. So blocking the lingual nerve best explains numbness of the anterior two-thirds of the tongue.

The main concept being tested is which nerve provides the sensory innervation to the front part of the tongue. The lingual nerve, a branch of the mandibular division of the trigeminal nerve, carries general sensation from the anterior two-thirds of the tongue. When this nerve is anesthetized, numbness occurs in that region. In addition, taste fibers from the anterior two-thirds travel with the lingual nerve via the chorda tympani, so anesthesia there can also affect taste in that area. The glossopharyngeal nerve supplies the posterior third of the tongue, the hypoglossal nerve is motor to the tongue muscles, and the inferior alveolar nerve supplies the lower teeth and surrounding areas, not the tongue. So blocking the lingual nerve best explains numbness of the anterior two-thirds of the tongue.