Hypoglossal Nerve

Description

Emerging from the hypoglossal canal at the skull base, the hypoglossal nerve (CN XII) descends in the upper neck deep to the sternocleidomastoid and in close proximity to the carotid sheath, with the internal carotid artery and internal jugular vein positioned anterolateral to the prevertebral compartment. It then sweeps anteriorly toward the floor of the mouth, passing near the angle of the mandible and approaching the lateral surface of the hyoglossus to distribute to the intrinsic and extrinsic tongue musculature. Nearby cervical nerve contributions are suggested in the field, including the superior root of the ansa cervicalis traveling with CN XII for a short distance before coursing inferiorly. Orientation is clear. This oblique lateral neck depiction matters because it places CN XII in the same surgical corridor used for carotid endarterectomy and selective neck dissection, where the nerve is at risk as it crosses the carotid bifurcation and interfaces with the carotid sheath. Iatrogenic hypoglossal neuropraxia presents with ipsilateral tongue weakness and deviation toward the injured side, a complication clinicians must distinguish from marginal mandibular facial nerve injury and recurrent laryngeal nerve dysfunction when postoperative dysarthria is reported. The relationship to the laryngeal framework and suprahyoid region also supports teaching the functional anatomy of tongue protrusion and bolus propulsion. Use this artwork for head and neck anatomy courses, cranial nerve lesion localization teaching, and operative anatomy figures in vascular surgery, otolaryngology, and oral and maxillofacial publications discussing carotid approaches and neck-level dissections. It also suits patient-facing counseling graphics for CN XII palsy after carotid surgery or skull base procedures. Anatomical accuracy verified by SciePro's Medical Advisory Board.