There are many clinical conditions that can cause numbness in the lower arm. The most common ones are acute trauma or chronic long-term strain or injury to the small arm, resulting in damage to the muscles of the small arm, poor blood flow and stagnation of blood and Qi, resulting in numbness in the small arm. If the patient suffers from elbow canal syndrome or humeral epicondylitis, the patient will have numbness in the small arm. Some patients may also have nerve entrapment symptoms, such as numbness and muscle weakness in the fingers. This phenomenon will be gradually relieved after prying and releasing with a small needle. Also if the patient has a cervical disc herniation leading to cervical spondylosis, numbness in the small arm may occur. A clear diagnosis can be made after taking an MRI film. Treatment is conservative, and if conservative treatment is not effective, then surgery is considered.