BASIC PRINCIPLES IN ELECTROMYOGRAPHY

This test enables the physician to evaluate the functional activity of the motor unit, It can be a major contributor in the diagnosis of conditions affecting the nerves and the skeletal muscle fibers. The purpose of the test is not to make a diagnosis of a disease, but to assess the functional status of the nerves and the skeletal muscle fibers as mentioned above. The proper localization of the intended muscle with the needle electrode is of paramount importance. The small size of the muscles (as in the hand and facial muscles) and the proximity among them (as in the forearm) makes the use of a clean technique a very important part of the test. 

The motor unit (M.U.) is a functional unit which is composed of the 

This test essentially consists of displaying the electrical activity of a living muscle using an intramuscular wire electrode which is placed transcutaneously on the intended muscle. This signal can be converted into a sound and played to a loudspeaker it can be stored on magnetic tape or printed out using electronic printer or light-sensitive paper. 

The muscle under study is evaluated during four different stages  

During electrode insertion 2. When the muscle is at rest 

---