Muscle atrophy is just the name of the symptom, which can be caused by many diseases. Muscle atrophy can be divided into neurogenic muscle atrophy and myogenic muscle atrophy, and the same is true for lower extremity muscle atrophy. Lower extremity muscle atrophy can be caused by nerve damage, which can occur in lumbar spine lesions leading to nerve root damage, or sciatic nerve damage from various causes, or cervical or peroneal nerve damage; and can be seen in hereditary peripheral neuropathies, distal type myopathies such as distal muscular dystrophy, and of course also distal upper extremity muscle atrophy; and also immune-mediated due to viral infections peripheral neuropathy; or the presence of myositis. In conclusion, the causes of lower limb muscle atrophy are complex and must be carefully identified. The etiology can also be clarified by means of cardiac enzymes, electromyography, as well as immunological tests and genetic testing.