Abstract
The ontogeny of the lips, tongue, and mandibular movements in 19 healthy Japanese infants, aged 5 to 12 months, was observed and videotaped during each meal for 3 consecutive days twice a month. The infants improved the lip closure function 2 months after weaning. Despite marked individual differences, all of the inter-quartile ranges for the starting age of any oral motor function were less than 1.1 months. The tongue and mandibular movements during feeding of semi-solid food differed from those of solid food. This finding indicates the essential role of the timing for introducing solid food in the development of chewing ability and the promotion of masticatory motor control.
