Fontanelle
A fontanelle is a soft spot on a baby's skull where the bones have not yet fused together. These areas are made of flexible tissue, allowing for growth of the brain and skull during infancy. The most well-known fontanelle is the anterior fontanelle, located at the top of the head, which typically closes by the age of 18 months.
Fontanelles serve an important purpose in protecting the baby's brain and facilitating childbirth. As the baby passes through the birth canal, the fontanelles allow the skull to compress slightly, making delivery easier. Other fontanelles, like the posterior fontanelle, are smaller and close earlier, usually by 2 to 3 months of age.