The hyoglossus muscle is a muscle of the tongue that depresses and retracts the tongue when contracted. It is one of four extrinsic tongue muscles - muscles that originate from a position outside of the tongue.
The hyoglossus acts to depress and retract the tongue. Changes in the shape and size of the oral cavity that are created by tongue movements change the quality of the sound that issues from a persons mouth. Since the hyoglossus muscle is part of the system that controls tongue movement, this makes the hyoglossus muscle important for both speaking and singing.
Due to the protected location of the hyoglossus muscle, this muscle is not easily damaged. Injury to the hyoglossus is generally the result of a stabbing wound or a stroke. Depending on the location of the injury, recovery may be limited.