The fontanel of a newborn is divided into anterior fontanel, which is in the center of the front part of the head, and posterior fontanel, which is near the occipital part of the head. The anterior fontanel, in the center of the front part of the head, is a diamond-shaped gap formed by the bone gap between the frontal and parietal bones on both sides, and is usually about 1 to 2 cm long and wide in newborns. The posterior fontanel is near the occipital region of the head and is a triangular gap formed by the bony suture between the parietal and occipital bones on both sides. The fontanel is soft to the touch because it is not protected by the skull. The anterior fontanel does not close until about 1.5-2 years after birth, while the posterior fontanel closes at birth or 6-8 weeks after birth. The fontanel can reflect some diseases. When the baby has encephalitis, meningitis and other diseases that increase intracranial pressure, the fontanel may be protruding and its diameter may increase; when the baby has symptoms such as dehydration, the fontanel may be sunken.