Fingers inwardly clasped, which means the fingers are clenched in a fist and the thumb is inwardly retracted, is usually associated with physiological factors, delayed brain development, and damage to the brain nerves. Physiological causes generally 3~4 months can disappear, the disease causes the symptom recovery time is not certain, may be accompanied by lifelong. 1. Physiological phenomenon: this type of finger inward fastening is a normal reaction, usually occurring after the birth of the baby, often related to limb incoordination. The symptoms will gradually disappear after ageing, which takes about 3~4 months. 2. Brain developmental delay: For example, cerebral palsy caused by the finger inward snap, this factor can not be completely cured, so the symptoms of finger inward snap may also exist for a lifetime. 3. Brain nerve damage: mostly related to acquired factors, when the brain nerve is damaged and the motor ability is reduced, the thumb may buckle. If timely treatment can be provided, the phenomenon can be effectively improved, but the recovery period is relatively long. If you find the phenomenon of thumb inward fastening, you must send to the hospital for examination as soon as possible, analyze the cause of the disease and then actively deal with it.