The bregma is the point on the skull where the sagittal and coronal sutures intersect. It is located in the high forehead. This structure changes over time as people develop and the older people are, the less distinguishable the bregma will be. It can be used as a reference point for certain types of brain surgery, as the sutures of the skull provide a frame of reference for the structures in the underlying brain. Understanding the anatomy of the skull is important for neurosurgeons, as they may need to make repairs to the skull or access the brain through the skull to treat patients.
At birth, the bones of the skull are separated. This allows the skull to deform slightly during labor so that the baby can be born, and it provides some room to grow. The area where the bregma will be is marked by the anterior fontanelle, a soft spot between the frontal and parietal bones. By the age of two, this fontanelle is usually entirely closed and the bregma has formed where the bones meet up. Over time, the bone ossifies or hardens, along with the sutures in the skull, and the distinctive lines formed by the sutures start to smooth out.
In early childhood, the fontanelles can be palpated as part of a diagnostic evaluation during a routine baby exam or an exam to determine why a baby is not feeling well. If the fontanelle feels shrunken, it can indicate that a baby is dehydrated. Swelling and hardness can be indicative of high intracranial pressure or may mean that a baby has been crying vigorously.
If the fontanelle fails to close by the age of two, it is an indicator that the child may have a congenital condition. The most likely cause is cleidocranial dysostosis, a bone disorder characterized by underdeveloped bones. Some people with this condition have missing collarbones, and may experience other skeletal problems. It is relatively rare in the general population and treatment options vary depending on the severity of the condition.
In brain surgery, surgeons want to hit the right spot on the first try. Using the sutures, along with medical imaging studies of the patient's brain as a reference, they can select an appropriate point to make an incision so that they can access the brain. The bregma is one of the points on the skull that can be used for orientation before and during surgery.