Anatomy study note · Head and neck

Hypoglossal nerve

The twelfth cranial nerve (motor). It supplies the muscles of the tongue except palatoglossus and so controls its shape and movement.

Key points

• CN XII: hypoglossal canal.
• All tongue muscles except palatoglossus (vagus).
• Carries C1 → ansa cervicalis, thyrohyoid, geniohyoid.
• Tongue deviates to the paralysed side.
• XII: occipital myotomes → tongue muscles.
• Motor nuclei: basal lamina. Sensory nuclei: alar lamina.
• Nerve: epineurium → perineurium (blood–nerve barrier) → endoneurium.
• Cut nerve: Wallerian degeneration; regrows 0.5–3 mm/day.

The full note in the atlas also covers

Course · Branches · Histology · Development · Clinical notes

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Written from

• Snell’s Clinical Anatomy by Regions, 10th ed., ch. 12, PDF pp. 1682–1683, 1687, 1732
• Inderbir Singh’s Human Embryology, ch. 17, PDF pp. 312, 318; ch. 7, PDF p. 109; ch. 9, PDF p. 126; ch. 12, PDF p. 172
• BRS Cell Biology & Histology, 7th ed., ch. 9, PDF pp. 163–166, 166, 171–172

More from the head and neck

• Hypothalamus
• Inferior oblique
• Inferior rectus
• Insula
• Internal capsule
• Internal carotid artery
• Internal jugular vein
• Iris
• Lacrimal apparatus
• Laryngeal membranes and ligaments
• Larynx
• Lateral cricoarytenoid

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