From time to time, we encounter patients in clinical practice with hand muscle atrophy or muscle atrophy of the arms and lower limbs, as well as symptoms of weakness. Hand muscle atrophy, in particular, is often difficult to detect at the beginning and leads to disease progression and delayed treatment. If you find a depression in the tiger area or a depression between the metacarpals on the back of the hand in general, be alert to the possibility of muscle atrophy. It is important to see a doctor promptly when this occurs, and the preferred test is electromyography, which can clearly determine whether there is nerve damage or muscle problems. However, cervical MR is often the preferred test in clinical practice. Cervical MR can only find out whether there are cervical spine lesions, but cannot exclude neurology-related diseases, such as motor neuron disease and ulnar nerve damage (elbow canal syndrome, carpal ulnar canal syndrome).