A tongue tie also known as ankyloglossia, is a physical limitation that affects tongue mobility, function, and oral rest posture. It is present at birth and it is characterized by an abnormally tight or short lingual frenum (the string of tissue under the tongue). This may restrict the mobility of the front, middle and/or back of the tongue and forces the tongue to sit on the floor of the mouth.

Tongue ties can range from mild, with only a tiny fold of tissue holding the tip of the tongue, to severe, in which the entire bottom of the tongue connects to the floor of the mouth. This is called an anterior tongue tie. There can also be posterior tongue ties where a thick, tight frenulum near the base of the tongue restricts its motion.

A tongue tie is often the root cause of a low postured tongue. The muscles of the tongue are connected to many other muscles of the jaw, face, and neck. These accessory muscles may compensate during speech, swallowing, chewing, and breathing. Grinding, clenching, jaw pain, headaches, and neck and shoulder pain are common tongue tie symptoms that result from these accessory muscles activating/compensating for the lack of tongue movement. Mouth breathing, open mouth posture, and tongue thrust are often associated with a tongue tie