frenulum

Ah, you're right, mollusque. Frenum is usually reserved for the tongue thingy. Thanks for pointing that out.

I thought the frenum attached the tongue, and "frenulum" was used for smaller connectors, such as the one tying the upper lip to the gums in line with the philtrum.

The piece of skin that attaches your tongue to the bottom of your mouth (or any small fold of tissue that prevents an organ in the body from moving too far).

Edit: see above.