EMG activity in neck and masticatory muscles in relation to extension and flexion of the head

Publisher Website
Google Scholar
Abstract
Electromyography was used to determine postural activity in neck and masticatory muscles in relation to extension and flexion of the head. The material comprised 30 adults. Postural activity was recorded in the postcervical, sternocleido-mastoid, supra- and infrahyoid, anterior temporal and masseter regions during natural head position with the mandible at rest, and during 5, 10 and 20 degrees of extension and flexion. In the postcervical muscles tonic activity decreased when the head was held extended and increased when it was flexed. In the sternocleidomastoid muscle postural activity increased significantly during 20 degrees extension whilst during flexion, no changes were recorded. Supra- and infrahyoid muscles responded with increased activity during extension and during 20 degrees flexion of the head. Activity in the anterior temporal muscle varied considerably and no significant association with different head postures was found. Increased activity was recorded over the masseter muscle when the head was extended 10 and 20 degrees. No change in activity was registered during flexion. If the findings presented here are also applicable in cases of a long term alteration in head posture, compensatory muscle function caused by extension or flexion of the head may be one of the determinants of craniofacial morphology.

This publication has 2 references indexed in Scilit: