What is the nerve supply to the tongue in a typical adult patient?

Nerve Supply of the Tongue

The tongue receives sensory innervation from three cranial nerves (trigeminal CN V for general sensation to anterior two-thirds, glossopharyngeal CN IX for both general sensation and taste to posterior one-third, and facial CN VII for taste only to anterior two-thirds), while motor innervation is provided exclusively by the hypoglossal nerve (CN XII). 1, 2, 3

Sensory Innervation

General Sensation (Pain, Temperature, Touch)

• Anterior two-thirds of tongue: The trigeminal nerve (CN V), specifically the lingual branch of the mandibular division (V3), provides all general sensory information including pain and temperature sensation 1
• Posterior one-third of tongue: The glossopharyngeal nerve (CN IX) provides general sensation to this region 2, 4

Taste (Special Sensory)

• Anterior two-thirds of tongue: The facial nerve (CN VII) via the chorda tympani branch carries taste sensation, but importantly does NOT transmit general sensory information like pain 1
• Posterior one-third of tongue: The glossopharyngeal nerve (CN IX) provides both taste AND general sensation to this region 2, 4

Motor Innervation

• All intrinsic and extrinsic tongue muscles: The hypoglossal nerve (CN XII) provides complete motor innervation to the tongue, controlling movements essential for chewing, swallowing, and articulation 3, 5, 6

Clinical Pitfalls and Key Distinctions

Common Misconception About Pain Sensation

• A scalded or injured tongue tip transmits pain through the trigeminal nerve (CN V), NOT the facial nerve, even though the facial nerve provides taste to this same region 1
• The facial nerve's role is limited to special sensory (taste) function only; it does not carry general sensory information 1

Anatomical Vulnerability

• The glossopharyngeal (CN IX) and vagus (CN X) nerves travel together through the jugular foramen, making them vulnerable to combined injury from single lesions 2
• The hypoglossal nerve has a long extracranial course making it susceptible to trauma, tumors, aneurysms, dissections, and iatrogenic injury from surgery or airway management 3

Isolated Deficits

• Bilateral hypoglossal nerve injury results in severe disability affecting swallowing and speech, though isolated bilateral injury is extremely rare 6
• Glossopharyngeal neuralgia presents with severe oropharyngeal and otic pain triggered by swallowing, and pain may be confined to the posterior tongue or ear only (via Jacobson's nerve branch) 4

Diagnostic Approach for Suspected Nerve Pathology

• For trigeminal nerve pathology: MRI is the preferred imaging modality 1
• For glossopharyngeal nerve evaluation: Contrast-enhanced MRI of the orbits, face, and neck with thin-cut high-resolution sequences through the posterior fossa and jugular foramen 2, 4
• For hypoglossal nerve assessment: Imaging should cover both intracranial and extracranial components 5