Dynamic grain, or muscle wrinkles, are wrinkles caused by muscle movement, such as crow's feet, forehead lines, frown, which will disappear or ease without expression. According to the data, the causes and severity of dynamic wrinkles are closely related to the amplitude and frequency of the facial expression muscles. It appears mainly due to photoaging, bad habits, skin water shortage, irregular life, lack of sleep, excessive weight loss and so on. Hyawell Derm & Deep are your choice.