Abstract
Tongue movements participate in oro-facial motor functions including chewing, sucking, swallowing, speech and respiration. During mastication and swallowing, tongue plays an important role of squeezing foods to make food bolus, and transporting them from the oral cavity to the pharynx. However, up to now our knowledge as to the functional role of tongue is still limited due to the technical difficulty to record the dynamic activity of tongue muscles. To this end, we recorded EMG activity of extrinsic tongue muscle in healthy subjects. In addition, tongue pressure against the hard palate as well as EMG activity in the submental muscle and laryngeal movements were also recorded. The subject was instructed to swallow test foods or water with different hardness. The same tasks were also tested in different postures which were upright and body reclined at 30 degrees. Patterns of tongue muscle activity and tongue pressure varied among the test foods and postures. When the subject swallowed hard food, tongue muscle activity and pressure were larger and the duration was longer as compared with soft food or water swallowing. When compared among the postures, the amplitudes tended to be larger as the body reclined. Contrary to these changes, the submental muscle activity hardly changed regardless of conditions. The results suggest that human tongue activity may be modulated by the peripheral inputs and/or subject’s posture during swallowing function. [Jpn J Physiol 55 Suppl:S173 (2005)]
