Hypoglossal nerve (CN XII)

Nervus hypoglossus

NervousNervesHeadLeft and right

View left in 3D View right in 3D

What it is
Emerges from the medulla as a line of rootlets between the pyramid and the olive, leaves the skull through the hypoglossal canal, descends lateral to the carotid arteries, then hooks forward just above the hyoid bone into the underside of the tongue.
Function
Motor to all the muscles of the tongue except palatoglossus - protrusion, retraction and shaping for speech and swallowing.
Size
About 1.5 mm thick, ~11 cm
Clinical note
Ask a patient to stick out the tongue: with a hypoglossal palsy it deviates TOWARD the weak side, because the healthy genioglossus pushes it across.

Nearby nervous structures Abducens nerve (CN VI), Abducens nerve root (CN VI), Accessory nerve root (CN XI), Facial nerve, terminal branches, Glossopharyngeal nerve (CN IX), Hypoglossal nerve root (CN XII), Mandibular nerve (V3), Maxillary nerve (V2), Medulla oblongata, Trigeminal ganglion