A frenum is also referred to as a frenulum. It is a tissue fold that connects soft tissue in the mouth. Sometimes it contains muscle tissue. There are two frena present in the mouth. The upper frenum attaches the lip to the gum tissue. It is called the maxillary labial frenum. The maxillary labial frenum is located above the two top teeth. The second frenum is called lingual frenum, and it connects the floor of the mouth to the tongue.