Nerve · Head

Hypoglossal nerve

Nervus hypoglossus

The hypoglossal nerve is the tongue's motor nerve, and almost nothing else. It supplies every muscle that shapes the tongue and every muscle that moves it, with one exception — palatoglossus, which belongs to the pharyngeal plexus. Its fibres leave the medulla between the pyramid and the olive, gather into a trunk that passes out of the skull through its own hypoglossal canal in the occipital bone, then swing forward across the neck above the greater horn of the hyoid to run under the tongue. It carries no sensation at all. One quirk causes lasting confusion: fibres from the first cervical nerve hitch a ride along it for part of the journey and then leave again as the nerve to thyrohyoid, the nerve to geniohyoid, and the superior root of the ansa cervicalis — so several strap muscles of the neck look as though they are supplied by the hypoglossal nerve when they are not.