Cranial Nerve XII: The Hypoglossal Nerve

Abstract

The hypoglossal nerve provides motor innervation to the tongue, and may be affected by pathology at multiple locations along its pathway. Knowledge of its anatomy and careful examination of the tongue are important in the diagnosis of lesions and determination of appropriate testing. The hypoglossal nerve anatomy and physiology, clinical disorders, and the evaluation of the hypoglossal nerve are reviewed.

Hypoglossal Nerve Palsy After Airway Management for General Anesthesia

“…65 Later physical examination findings revealed unilateral atrophy and genioglossus muscle fasciculation, signifying denervation-reinnervation injury. 66,67 …”

“…At the mandibular angle, it passes anteriorly, deep to the posterior belly of the digastric muscle and reaches the submandibular region to enter the tongue. 67 At the undersurface of the tongue, numerous branches pass upward to supply its intrinsic muscles. 11,29,67 The 4 mechanisms of injury leading to HNP proposed in the literature are described in Figure 2.…”

“…67 At the undersurface of the tongue, numerous branches pass upward to supply its intrinsic muscles. 11,29,67 The 4 mechanisms of injury leading to HNP proposed in the literature are described in Figure 2. Tapia’s syndrome (unilateral recurrent laryngeal nerve and hypoglossal nerve paralysis), a subset of hypoglossal nerve injury, is attributed to compression injury to intersecting extracranial fibers of both the hypoglossal and vagus nerves at the base of the tongue.…”

Hypoglossal Nerve Palsy Following Chiropractic Neck Manipulation

“…The HN exits the base of the skull through the hypoglossal canal and descends in the neck between the sternocleidomastoid and internal carotid artery, lateral to the vagus nerve, to reach the stylopharyngeal, styloglossus, and stylohyoid muscles. 1,2 The HN is joined by the C1 nerve fibers which branch off to innervate the geniohyoid and thyrohyoid muscles, also supplying descending nerve fibers to the infrahyoid muscles. 2 These descending fibers receive contribution from C2 and C3 nerve fibers as well, which is known as the ansa cervicalis.…”

“…1,2 The HN is joined by the C1 nerve fibers which branch off to innervate the geniohyoid and thyrohyoid muscles, also supplying descending nerve fibers to the infrahyoid muscles. 2 These descending fibers receive contribution from C2 and C3 nerve fibers as well, which is known as the ansa cervicalis. 2 Tongue weakness following trauma has been well described in the context of hematoma, 3 localized swelling, 4 internal carotid artery dissection, 5 and cervical fracture (occipital condyle), 6 but these structural findings were not relevant in our patient.…”