Abstract
The paper designed to raise the sole of one side of the foot to indirectly cause body imbalance. detecting the surface electromyographic activities(SEMG) of sternocleidomastoid muscle (SCM), trapezius muscle (TR), temporal muscle(TA) and masseter muscle (MM) in mandibularpostural posture (MPP). So as to analyzed the influence of plantar afferent signal changes on the above muscle functions, and elaborated the correlation between body posture and maxillofacial and neck muscle functions. Eleven asymptomatic subjects (4 males and 7 females, ages 20-30 years) were included in this study. Disturbing the balance of body posture by lifting the one side of foot with hard boards in MPP. Recorded the SEMG of TA, MM, SCM, TR by using COMETA surface electromyography in the condition of 0.5cm, 1.0cm and 1.5cm of the planthole padded up on one side and without the planthole padded up. Analysing the changes of the average SEMG of TA, MM, SCM and TR under different plantar pad heights in MPP. In the unpadded condition, the SEMG of SCM was the most obvious, followed by TA and TR, and the SEMG of MM was the weakest. The average SEMG of left SCM and TR were significantly higher than those of right SCM and TR (P<0.05). Under the condition of respectively raising the left and right plantar, the average SEMG of the padded and non-padded TR increased gradually with the increase of the foot height step by step, which was significantly higher than that of the ipsilateral TR in the unpadded condition (P<0.05). The average SEMG of the pad side increased with the increase of the foot height (P<0.05), but not obvious on the unpad side (P>0.05). The average SEMG of the left MM decreased with the increase of the right planthar height (P<0.05), while there was no statistical difference in the average SEMG of the high side and the non-high side compared with the same side under the other high conditions (P>0.05). And the average SEMG of TA was also not significantly affected by the height of the plantar pad (P>0.05). Based on these findings, it can concluded that the body posture imbalance caused by unilateral plantar cushion can change the SEMG of sternocleidomastoid muscle, trapezius muscle, temporalis muscle and masseter muscle in mandibular posture. The sternocleidomastoid muscle and trapezius muscle have strong response to plantar cushion stimulation, so as to improve the EMG activity intensity in mandibular posture and maintain the normal position of the mandible. This study reveals that the change of body posture caused by the change of plantar afferent signal can regulate and stabilize the mandibular position through the ascending muscle chain.