Related Experiment Video
Updated: Jun 1, 2026

An Implantable System For Chronic In Vivo Electromyography
Published on: April 21, 2020
[Electromyographic activity of sternocleidomastoid and masticatory muscle in patients with prognathism]
1Dept. of Oral Anatomy and Physiology, School of Stomatology, China Medical University, Shenyang 110002, China.
Objective:
To investigate the electromyographic activities of anterior temporalis (TA), masseter muscle (MM), digastric anterior (DA), sternocleidomastoid (SCM) at postural position (MPP) and various mandibular movements in prognathic patients.
Methods:
Thirty-two patients with prognathism were selected from the clinic of oral and maxillofacial surgery of China Medical University. 36 healthy college students with normal occlusion were selected as normal controls. A BioEMG II diagnostic system with BioFLEX surface electrode was used to record the electromyographic activities of the above muscles.
Results:
Compared with the control group, the electromyographic activities of TA, SCM and DA in prognathic patients were higher in MPP. The electromyographic activities of TA, MM were significantly lower than the control group in clenching (P < 0.01). In protrusion, the electromyographic activities of TA, MM and SCM in prognathic patients were higher than the control group (P < 0.01). In retrusion, the electromyographic activities of TA, SCM in prognathic patients were higher than the control group (P < 0.01).
Conclusion:
The masticatory muscles electromyographic activity of prognathism is abnormal.
Related Concept Videos
Muscles for Facial Expressions
Muscles of the Anterior Neck
Muscles that Move the Head
The bilateral sternocleidomastoid, or SCM, and the suprahyoid and infrahyoid muscles are significant head flexors. The SCM muscles originate at the sternum and clavicle and attach to the mastoid process of the temporal bone. The SCM contracts bilaterally to bend the head forward, whereas...
Assessment of Airway, Skin Color, and Use of Accessory Muscles
Introduction
The initial evaluation of a patient's respiratory system...
Myasthenia Gravis: Diagnostic Tests
The edrophonium test is a diagnostic tool for myasthenia gravis. It involves...

