hypoglossal nerve

Full Definition

The hypoglossal nerve is the twelfth cranial nerve, providing motor innervation to the intrinsic and most extrinsic muscles of the tongue. In head and neck oncology, this nerve is at risk during neck dissections, particularly those involving the carotid sheath or skull base procedures. Injury results in ipsilateral tongue weakness with deviation toward the affected side, causing difficulties with articulation, mastication, and swallowing. Bilateral injury can be life-threatening due to airway obstruction.

In Context

• "The hypoglossal nerve was identified and preserved during the level I neck dissection." — Operative note
• "Post-operative examination revealed left hypoglossal nerve dysfunction with tongue deviation." — Clinical examination