Anatomy and Function
At this point, you may be wondering what part of the brain controls the tongue. The twelfth cranial nerve comes from the medulla oblongata, a part of the brain stem. From there, it passes through the space underneath the tongue to reach the tongue muscles. Did you know that the hypoglossal nerve's name comes from the path it takes below the tongue? "Hypo" means below, and "glossal" means relating to the tongue.
The hypoglossal nerve is a motor nerve, and it controls the muscles of the tongue that allow for speech and swallowing. The tongue's extrinsic muscles help it move in different directions, while the intrinsic muscles help it make movements such as curling. The extrinsic muscles controlled by the hypoglossal nerve are as follows:
- The genioglossus muscle helps move the tongue out of the mouth.
- The hyoglossus muscle moves the tongue down to flatten it.
- The styloglossus muscle retracts the tongue back into the mouth and elevates it.
Clinical Oral Anatomy notes that there is another extrinsic muscle, but the hypoglossal nerve does not control it. This muscle is the palatoglossus muscle.