The purpose of the study was to investigate the functional change of the perioral muscle activities during breast feeding in infants after birth.
Fifty six normal fullterm infants participated in the study. The infants were classified into five groups; from the 1st,2nd,3rd,4th and 5th month depending on their age in months after birth. Each subject was breast-fed by its mother sitting on a chair in a shielded room. During breast feeding, electromyograms (EMG) were obtained unilaterally from the temporalis (TM), the masseter (MM), the orbicularis oris (OM) and the suprahyoid muscles (SM) of the baby using bipolar surface electrodes. EMG signals were recorded on a thermal array recorder and a data recorder. At the same time, maxillofacial movements during sucking were recorded by a video camera. Employing a video formatter and frame synchronizer, EMGs and maxillofacial movements were simultaneously scanned on a monitor, and this then was recorded on a video-recorder. EMG activities and the sucking cycles were measured on the first ten rhythmical EMGs at the start of breast feeding, and these were then compared between groups.
Following were results;
1. The SM activity intensified as the age incrcased. There was a significant difference between the 1st and 5th month babies (p <0.05), while no increase was noticed in the TM, MM, OM activities.
2. The total muscle activities intensified remarkably through the ages of the 1st to the 3rd month in babies, while any apparent changes from the 3rd to 5th in month were seen.
3. The sucking rhythm did not vary between age groups. The sucking cycle time was 0.6-0.7s.
It may be concluded that during sucking movement in breast-feeding babies, both the perioral and the suprahyoid muscles play a leading role, which suggest an active functioning of the tongue during sucking.