What is Electromyography?
One of the diagnostic tools used in identifying and
analysing TMJ dysfunctions is electromyography, which is
a cousin of the electrocardiogram. As the
electrocardiogram measures the muscular activity of
dysfunctions of the heart muscle, electromyography
measures the activity and dysfunction of head and neck
muscles. This information is important in treatment
planning and for documentation purposes.

How does it work?
EMG equipment evaluates muscle tension through
sensors that are placed over the head (see picture). This
valuable information tells the practitioner if the problem is
ascending up the spinal cord from below the neck or the
problem is descending. This is very important in
correcting posture problems that are either the origin or
the effect of the temporomandibular disorder. Swallowing
and bite problems are identified so that they can be
treated

In Support of the Efficacy of EMG
Surface electromyography has been used by researchers
(120 studies) and clinicians (2000+ in the U.S.) for over
twenty years. It is the only quantitative method to measure
and document the severity, progression, and treatment of
muscle dysfunction in the craniomandibular patient.
Over forty dental schools world-wide have produced over
120 studies - all validating two central facts regarding
muscle activity:

1. Patients with craniomandibular dysfunction have
distinctly different patterns of muscle activity (at rest, in
clench, while chewing, and while speaking) than the
asymptomatic "normal" subject. So EMG clearly confirms
and quantifies the presence and severity of this muscle
dysfunction.

2. Successful treatment reduces the irregularity and
severity of muscle dysfunction. So comparison of
post-treatment muscle activity with pre-treatment muscle
activity baseline documents treatment efficacy.

http://www.drjjedderai.com/tmj_elm.html
http://www.tmj-tmd.com/articles.htm