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What is Electromyography/ EMG?

EMG is used to diagnose diseases of the nerves and muscles. It's a recording of electrical activity in muscles.

ELECTRO = electric
MYO = muscle
GRAPHY = writing

The permanent recording made during an EMG is called an "electromyogram."

How EMG Works

• A tiny needle is inserted into a muscle to record it's electrical activity (any electrical response to the needle's insertion will be noted).
• An amplifier increases the strength of the electrical signal from the muscle.
• The oscilloscope (which looks like a television or computers screen) displays the image. Different diseases show different patterns on the screen.
• Loudspeakers are often used so sounds produced by electrical signals can be analyzed.
• Recordings are taken while the muscle is at rest and while the muscle contracts. The muscle will be evaluated at rest. Normally, there is no electrical activity in a resting muscle.
• You will flex the muscle as hard as you can. As your effort increases, more motor units are called into action.