Hypoglossal Nerve

The hypoglossal nerve is the twelfth cranial nerve (XII), leading to the tongue. The nerve arises from the hypoglossal nucleus and emerges from the medulla oblongata in the preolivary sulcus separating the olive and the pyramid. It then passes through the hypoglossal canal. On emerging from the hypoglossal canal, it gives off a small meningeal branch and picks up a branch from the anterior ramus of C1. It spirals behind the vagus nerve and passes between the internal carotid artery and internal jugular vein lying on the carotid sheath. After passing deep to the posterior belly of the digastric muscle, it passes to the submandibular region, passes lateral to the Hyoglossus muscle, and inferior to the lingual nerve to reach and efferently innervate the tongue.

It supplies motor fibres to all of the muscles of the tongue, except the palatoglossus muscle, which is innervated by the vagus nerve (cranial nerve X) or, according to some classifications, by fibres from the glossopharyngeal nerve (cranial nerve IX) that "hitchhike" within the vagus. It controls tongue movements of speech, food manipulation, and swallowing.

The hypoglossal nerve is derived from the basal plate of the embryonic medulla oblongata.

Swallowing to clear mouth of saliva and other involuntary activities completed by the tongue are controlled by the hypoglossal nerve; however, most functions are voluntary. Voluntary control requires conscious thought and nerve pathways occur in the corticobulbar region in the spinal cord.

The function of the hypoglossal nerve in manipulation for speech contributes to learning languages. Many languages require specific and sometimes unusual uses to create the desired sounds, hence why adults learning a new language may have trouble adjusting to the new movements.