Hypoglossal Nerve

Description

Arising from the preolivary sulcus of the medulla oblongata, the hypoglossal nerve (CN XII) is shown as multiple rootlets that coalesce and course anterolaterally toward the upper neck. Nearby cranial nerves emerging from the pontomedullary junction and lateral medulla are also visible, creating a clear map of the brainstem exit zones. Distal to its exit from the skull base, CN XII loops in close proximity to the occipital artery before continuing anteriorly toward the tongue musculature. Spatially, this places the nerve inferior to the posterior cranial fossa structures and anterior to the upper cervical soft tissues, with the arterial loop serving as a practical landmark. That relationship to the occipital artery matters because CN XII is vulnerable during carotid endarterectomy, submandibular and upper neck dissections, and skull base exposure around the hypoglossal canal. One nick, one neuropraxia, and the clinical picture is unmistakable. Ipsilateral tongue deviation on protrusion, dysarthria, and later hemiglossal atrophy point directly to hypoglossal injury, and the illustration helps separate a lower motor neuron CN XII lesion from supranuclear weakness where deviation may be subtler and accompanied by other long tract signs. Neuroanatomy courses and cranial nerve practicals can use this plate to teach rootlet origin on the medulla, side-by-side comparison with adjacent cranial nerves, and the early extracranial course relevant to head and neck surgery. It also fits well in operative anatomy chapters, radiology teaching files correlating skull base lesions near the hypoglossal canal, and patient education materials explaining hypoglossal palsy after vascular or oncologic procedures. Anatomical accuracy verified by SciePro's Medical Advisory Board.