Skull of a human newborn baby showing the uncalcified areas or fontanelles between the skull or calvarial bones. The fontanelles give the newborn's skull flexibility, allowing it to pass through the birth canal. At least six fontanelles are present at birth, the largest being the anterior fontanelle or soft spot on top of a baby's head. The fontanelles close during the first two years of life as the edges of the calvarial bones grow.