Sometimes the frenulum can be attached to the back of the lower gum ridge as well as the floor of the mouth. (second9months.com)
The tongue tied baby also will be unable to protrude the tongue horizontally past the gum ridge or lips, because of tension on the short or tight frenum in this posture. (tonguetie.net)
Thus, accepting the solid food by opening the mouth widely enough to receive the spoon can be affected by a habit of inadequate mouth opening (see breastfeeding), the tongue may not protrude over the gum ridge, instead it will hump at the back of the mouth and push the food out rather than draw it in. (tonguetie.net)