Swallowing begins as the tongue mixes food with saliva to form a food bolus, which is then propelled into the pharynx by the tongue. Articulation also depends on the tongue's ability to alter the impedance of air, and change the resonant characteristics of the upper airway. In macroglossia, increased tongue bulk may impair these functions. Differential growth of the tongue and other facial structures affects tongue position in infants and children. The tongue growth is similar to neural tissue, with the majority of growth occurring early.
Maxillary growth is slower, but similar to the tongue.
The mandible grows more slowly, with two peaks of growth. One occurs between the ages of 8 -12 and the second growth phase occurs with puberty. This differential of growth leads to the tongue having a high and forward position in the early years which may accentuate macroglossia. Macroglossia may be classified in several ways. A classification by Meyer et al divides the causes into generalized and localized based on the extent of tongue involvement.