Muscles of the tongue are contracting tissues used to rotate and arrange food for chewing as well as to form sounds in spoken language. There are two major types of tongue muscles: intrinsic muscles and extrinsic muscles. The entire tongue is composed primarily of muscles covered by a thick membrane. These muscles are arranged symmetrically with the same muscles on the right existing on the left and separated in the center by the median septum.
Extrinsic muscles of the tongue are those that attach to the outside of the tongue from the jaw, the floor of the mouth or rear of the oral cavity; there are four main ones. The genioglossus muscle is an extrinsic muscle that enables forward movement; it attaches to the front of the jaw and allows the tongue to thrust outside of the mouth. Styloglossus is the muscle that lifts the tongue up and pulls it backward.
Extreme lifts of the tongue are accomplished by the mylohyoid muscle. The hyoglossus muscle depresses the tongue, sliding it downward and in a rear direction. By lifting the tongue, and looking underneath it, one can spy sinews connecting the underside of the tongue to the oral cavity. Smaller, secondary extrinsic muscles assist these four main ones in completing their movements
Intrinsic muscles of the tongue are those situated inside the tongue. The superior longitudinal muscle runs lengthwise from the front of the tongue to the back; it’s located on the top of the tongue just beneath the membrane. Sides of the tongue are supported by intrinsic muscles known as inferior longitudinal muscles and verticalis muscles; they allow the tongue to curl, swish from cheek to cheek, and contort into various shapes.
Whether a person is awake or asleep, the muscles of the tongue are consistently working. During food consumption, tongue muscles situate food under teeth for grinding and then position the food for swallowing. In speech, the tongue interacts with the teeth and the roof of the mouth to blend sounds and form letter combinations. At night during slumber, the tongue circulates saliva and initiates swallows.
In order for tongue muscles to move the tongue, nerves embedded in the tongue must communicate orders from the brain to the muscles of the tongue. Neurological damage or diseases, such as pseudobulbar palsy, can cause motor problems for the tongue. Lack of use can also cause motor problems because unused tongue muscles weaken and lose the ability to form words and guide food properly.