1. Defining Electromyography (EMG): EMG is the study of the electrical activity produced by skeletal muscles. To record this activity with high precision—especially for "Motor Unit Action Potentials" (MUAPs)—clinicians need to get close to the individual muscle fibers.
2. Role of the Needle Electrode: A needle electrode is an invasive electrode that is inserted directly through the skin into the muscle tissue. This allows for the recording of localized electrical activity from a specific muscle group, which is far more accurate than surface electrodes that measure the sum of all muscle activity beneath the skin.
3. Analysis of other signals:
• EOG (Electrooculography): Measures eye movements; uses surface electrodes around the eyes.
• EEG (Electroencephalography): Measures brain waves; uses a cap or array of surface electrodes on the scalp.
• ECG (Electrocardiography): Measures heart activity; uses surface electrodes on the chest and limbs.
Because EMG often requires intramuscular data for diagnostic purposes (like detecting nerve damage or muscle disease), the needle electrode is its characteristic tool.