Before we are born, a strong cord of tissue (the frenulum) that guides development of mouth structures is positioned in the center of the mouth. After birth, the frenulum continues to guide the position of incoming teeth. As we grow, it recedes and thins.
This frenulum is visible and easily felt if you look in the mirror under your tongue. In some children, the frenulum is especially tight or fails to recede and may cause tongue mobility problems.
The tongue is one of the most important muscles for speech and swallowing. For this reason, having tongue tie can lead to eating or speech problems, which may be serious in some individuals. Posterior tongue tie is a nebulous term that lacks a clear definition or treatment.