The term Frenum (or Frenulum) refers to the small piece of tissue which connects the bottom lip or the top lip to the inside of the mouth. You can see the two Frenula inside your mouth when you pull your bottom lip down or pull your top lip up. There are also other Frenula inside your mouth which attach the cheeks to the bone, and which attach the bottom of the tongue to the inside of your mouth.
Synonyms:
Frenulum, Frenula, Labial Frenum