Electromyogram (EMG)

A diagnostic procedure used to assess the electrical activity produced by skeletal muscles. It involves the insertion of electrodes into the muscle tissue to measure and record the electrical impulses generated during muscle contraction and relaxation.

 

Motor Unit

A functional unit comprising a motor neuron and the muscle fibers it innervates. EMG helps in analyzing the recruitment and firing patterns of motor units.

 

Action Potential

The brief electrical signal that travels along the nerve fiber and stimulates muscle contraction. EMG captures action potentials generated by motor neurons to evaluate muscle function.

 

Insertional Activity

The electrical activity observed during the insertion of the EMG electrode into the muscle. It provides information about muscle membrane integrity and possible abnormalities.

 

Fibrillation

Spontaneous, irregular contractions of individual muscle fibers due to denervation or muscle pathology. EMG detects fibrillation potentials, indicating nerve damage or muscle disease.

 

Recruitment Pattern

The sequence in which motor units are activated during muscle contraction. EMG analysis helps identify abnormal recruitment patterns, which can signify neuromuscular disorders.

 

Interference Pattern

The summation of motor unit action potentials recorded during maximal muscle contraction. EMG measures interference patterns to assess muscle strength and detect abnormalities.

 

Motor Neuron Disease

A group of neurological disorders affecting motor neurons, leading to muscle weakness and atrophy. EMG aids in diagnosing motor neuron diseases like ALS (amyotrophic lateral sclerosis) by detecting characteristic abnormalities.

 

Needle EMG

A type of EMG technique involving the insertion of fine needle electrodes directly into the muscle tissue. It provides detailed information about the electrical activity of specific muscles and is particularly useful for diagnosing focal neuropathies or myopathies.

 

Surface EMG

An EMG technique that involves placing adhesive electrodes on the skin surface above the muscles of interest. Surface EMG is non-invasive and suitable for assessing muscle function during dynamic activities like gait analysis or sports performance evaluation.