Q: Are there developmental norms/standards for differentiation of tongue and mandible or lips and mandible?
A: I have been unable to find those particular norms and would welcome them if any of our readers have access to them. I came upon the realization clinically when I was screening 1000s of children over a period of several years. They were 3 years old and up in age. Almost none of the three year olds could demonstrate the separation of tongue and mandible, even the ones closer to age four. After age four, however, the majority of the children could imitate my modeling of lingual/mandibular and labial/mandibular differentiation. Those who could not do so were most often the ones in need of therapy of one sort or another.