Electromyography (EMG) is a test that records the bioelectrical activity of neuromuscles to determine their functional status for the diagnosis of neuromuscular diseases. In a narrow sense, it refers to the electrical activity of the muscle at rest and in different degrees of contraction recorded by concentric needle electrodes inserted into the muscle. Broadly speaking, it is a technique to record various electrophysiological characteristics of muscles in resting state, random contraction and peripheral nerve stimulation, including nerve conduction velocity, repetitive nerve electrical stimulation, single-fiber electromyography and giant electromyography. Clinical significance Normal muscle fibers are innervated by nerves. Many pathological processes impair innervation to varying degrees, manifesting partial and complete loss of innervation and various abnormal EMG. The clinical significance of EMG examination is to diagnose and differentiate neurogenic from myogenic diseases, neuromuscular junction lesions, and to detect subclinical or easily overlooked lesions, such as early onset motor neuron disease, profound myasthenia, and myasthenia in obese children, and to localize and diagnose lesioned segments.