Related Experiment Video
Updated: Jul 8, 2026
07:11
Treatment of Facial Deformities using 3D Planning and Printing of Patient-Specific Implants
Published on: May 23, 2020
Asymmetric muscle function in patients with developmental mandibular asymmetry
1Department of Oral Prosthodontics, College of Medicine, Second Affiliated Hospital, Zhe jiang University, Hang zhou, China. wenqing66_@yahoo.com.cn
Journal of Oral Rehabilitation
|January 15, 2008
Summary
Developmental mandibular asymmetry disrupts symmetric jaw and neck muscle activity, particularly in the sternocleidomastoid (SCM) and masseter muscles. This asymmetry may contribute to temporomandibular joint and cervical pain.
Area of Science:
- Biomedical Engineering
- Orthodontics
- Neuromuscular Physiology
Background:
- Developmental mandibular asymmetry, often linked to unilateral cross-bite, can affect craniofacial structures.
- Muscle activity patterns may be altered in individuals with mandibular asymmetry.
Purpose of the Study:
- To investigate the association between developmental mandibular asymmetry and muscle activity asymmetry.
- To compare muscle activation patterns in patients with mandibular asymmetry and healthy controls.
Main Methods:
- Electromyography (EMG) recorded muscle activity in masseter, suprahyoid, sternocleidomastoid (SCM), and upper trapezius muscles.
- EMG data (RMS and MPF) analyzed during jaw and head movements in patients with unilateral cross-bite and healthy subjects.
- Statistical analysis using ANOVA and t-tests to determine significance (P < 0.05).
Main Results:
- Significantly greater asymmetry in SCM and masseter muscle co-activation during jaw and head movements was observed in patients.
- Higher RMS and MPF values in SCM and suprahyoid muscles were found in patients during jaw opening-closing.
- Evidence of co-activation between jaw and neck muscles during jaw opening and postural activity in the masseter during head extension.
Conclusions:
- Patients with developmental mandibular asymmetry exhibit disturbed symmetric jaw and neck muscle activity.
- Asymmetric muscle activity is a potential etiologic factor for temporomandibular joint and cervical pain.
- Further research on early-stage patients is warranted to confirm activity sources and pain associations.
Related Concept Videos
01:14Muscles for Facial Expressions
The craniofacial muscles are a collection of approximately 20 thin skeletal muscles situated beneath the skin of the face and scalp. These muscles, primarily responsible for the vast array of human facial expressions, originate from the bones or fibrous structures of the skull and extend outwards to connect with the skin. While most skeletal muscles in the body are enveloped in thick fascia, facial muscles generally have a more delicate fascial covering, with the buccinator muscle being a...
01:18Axial and Appendicular Muscles
Skeletal muscles, the key players in our body's movement, can be classified into two groups based on their location and function: axial muscles and appendicular muscles. These classifications reflect the primary roles the muscles play in the body's structure and movement.
Axial Muscles
Axial muscles, situated along the body's midline, are intricately connected to the axial skeleton, which includes the skull, spine, ribs, and sternum. These muscles facilitate facial expressions and play a...
Axial Muscles
Axial muscles, situated along the body's midline, are intricately connected to the axial skeleton, which includes the skull, spine, ribs, and sternum. These muscles facilitate facial expressions and play a...
01:24Muscle Coordination and Action
Muscle coordination is a complex and finely tuned process essential for smooth and purposeful movements like flexion, extension, adduction, abduction, and rotation. The human body orchestrates the actions of various muscles working in concert, each with a specific role. Four functional types describe how muscles work together: agonist, antagonist, synergist, and fixator.
Agonists
Agonist muscles, often called prime movers, are the primary muscles responsible for producing a specific movement.
Agonists
Agonist muscles, often called prime movers, are the primary muscles responsible for producing a specific movement.
01:19Muscles that Move the Head
The muscles that move the head are a dynamic and complex group of structures that work together to facilitate a wide range of head movements, including rotation, flexion, extension, and lateral bending.
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...
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...