Electromyography (EMG) and Nerve Conduction Studies (NCS) are concerned with the recording, analysis and interpretation of the electrical activity of the peripheral nerves and muscles.

Although the general basic principles of receiving, amplifying and recording techniques are the same as those in electroencephalography, in practice there are differences in the measuring and operating methods used.

The EMG Apparatus

In its simplest form the EMG/NCS recording apparatus consists of one or more amplification systems, a display unit, a sound amplifier with loud speaker, a permanent storage system, stimulator and calibration unit. An instrument for measuring the skin temperature is also important. Machines these days will also include an ‘averager’, computer analysis as well as provision for a delay line.

Here is a simple block diagram of the EMG recording apparatus.