Co-ordination of tongue movements and peri-oral muscle activities during nutritive sucking.

A feeding bottle equipped with micro-video-camera and pressure sensor was devised to show the inside of the mouth and record sucking pressure. Activities of the temporal (TM), masseter muscle (MM), orbicular muscle of the mouth (OM) and suprahyoid muscles (SM) of 25 healthy infants were examined. Tongue and jaw movements, EMGs and sucking waves were scanned simultaneously. The tongue movements included elevation of the medial part of the tongue in a backward-moving peristaltic wave; significant correlations were found between jaw motion, tongue movement and sucking pressure. The TM, MM and OM were most active when the sucking pressure became positive and the jaw was closing, the SM showing highest activity in the negative-pressure phase. These findings show that each suckling cycle is biphasic, with sucking pressure, peri-oral muscle activities and jaw motion all closely correlated.