Changes in postural EMG activity in the neck and masticatory muscles following obstruction of the nasal airways

Abstract

The aim of the present investigation was to induce oral respiration in human subjects and to study how this, in the short term (30 minutes), affected head posture, mandibular posture, and postural activity in the postcervical, supra- and infrahyoid, anterior temporal, masseter and sternocleidomastoid muscles. The study comprised of 30 adults. Head posture, mandibular posture and postural muscle activity were recorded: (a) during normal breathing when the subjects were standing in natural posture and with the mandible at rest, (b) immediately following obstruction of the nasal airways and then after 1, 3, 5, 10, 15, 20 and 30 minutes of obstruction, and (c) after nose breathing had been re-established. Obstruction of the nasal airways resulted in an extension of the head and a lowered mandibular posture. Postural activity decreased significantly in the postcervical and anterior temporal muscles and tended to increase in the suprahyoid muscles. In the infrahyoid, masseter and sternocleido-mastoid muscles no change in activity could be recorded. When nasal obstruction was removed and nose breathing was resumed, the readings of the variables studied did not differ significantly from the values recorded before the mouth breathing experiment. The results of the present study suggest that a change in the mode of breathing is able to influence head posture, mandibular posture and postural activity in neck and masticatory muscles.