The cranium takes the line connecting the upper edge of the orbit and the upper edge of the external auditory canal as the demarcation line, and it can be divided into two parts: the cerebral cranium and the facial cranium, and the cerebral cranium is divided into the cranial skull and the skull base bone. Cranial bones can play a protective and supportive role for the brain.1. Cranial bones of the brain: refers to the cranial bones above the demarcation line, there are 8 pieces. Among them, the parietal and temporal bones are paired, each with 2 pieces, and the rest are the frontal, occipital, sieve and pterygoid bones, totaling 8 pieces. The inner plate of the skull at the parietal bone is not tightly connected to the endosteum, which can easily cause an epidural hematoma when a fracture occurs. The place where the frontal, parietal, pterygoid and temporal bones meet is called the pterygoid point, where the bone is weak and the anterior branch of the middle meningeal artery passes through. Once struck by violence, the broken bone fragments will puncture the middle meningeal artery, thus forming an epidural hematoma; 2. Facial and cranial bones: refers to the cranial bones below the demarcation line, with a total of 15 pieces. They include the paired maxillary bones, zygomatic bones, nasal bones, lacrimal bones, palatal bones and nasal turbinates, and also include the unpaired plow bones, mandibular bones and hyoid bones, for a total of 15 pieces. The main role of the skull base bones is the bony support and protection of the face, mouth, and nasal cavity. Among the skull base bones, the skull base can be further divided into the anterior, middle, and posterior cranial fossae by the pterygoid and petrocranial crests. Fractures of the anterior cranial fossa are weak and prone to fracture of the anterior cranial base when head trauma occurs, which is often characterized by “panda’s eyes” and nasal leakage of cerebrospinal fluid, and some patients may suffer from olfactory impairment. Various craniocerebral injuries often lead to skull fracture and skull base fracture, which need to be clearly diagnosed and guided by cranial plain radiographs, cranial CT, and even three-dimensional reconstruction of the skull base.