Cranial depressions are mostly caused by cranial injury, and to a lesser extent by congenital causes. The medical definition of skull depression caused by cranial injury is that the skull is depressed to a certain degree internally due to trauma, which is called a depressed fracture, also called skull depression. There are certain principles for dealing with depressed skull fractures. For infants and children, if the degree of depression does not exceed 5 mm and there are no clinical symptoms, the fracture does not need to be treated and can be reset or repaired by itself during the development of the child. In adults, if the skull depression fracture exceeds 10 mm and there are functional symptoms in the adjacent brain tissue, surgical repositioning is required. In addition, if the skull plate is depressed inward due to fixation problems during cranial surgery, it needs to be re-surgically treated and fixed.