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Hypoglossal Nerve

nervus hypoglossus (CN XII)

The hypoglossal nerve is the motor nerve to the tongue, supplying all tongue muscles except the palatoglossus (which is supplied by the vagus nerve via the pharyngeal plexus). Unilateral hypoglossal nerve palsy produces tongue deviation toward the paralysed side on protrusion, a sign produced by the unopposed action of the contralateral genioglossus pushing the tongue toward the weak side.

Region: Head & Skull

Anatomical Data

Origin, Insertion & Supply

Origin	Cranial nerve XII arising from the hypoglossal nucleus in the medulla oblongata

Clinical Relevance

Clinical Notes

Hypoglossal nerve palsy from stroke produces tongue deviation to the ipsilateral side (upper motor neurone, contralateral lesion) while peripheral nerve lesions produce deviation to the ipsilateral side of the lesion. Careful localisation is required. Hypoglossal nerve catheters are used for hypoglossal nerve stimulation (HNS) as a surgical treatment for obstructive sleep apnoea when CPAP has failed, producing tongue protrusion during sleep to maintain upper airway patency.

Pathology

Common Injuries & Conditions

Hypoglossal Nerve Palsy

Unilateral tongue paralysis producing deviation toward the affected side on protrusion, from stroke, base of skull fracture, or neck dissection, managed by treating the underlying cause.