The fontanel is an area consisting of a membrane between the bones of the skull in newborns. The young child's head has not yet finished growing at birth
and existence of fontanels allow the skull bones to continue to grow and reach their adult size. There are 4 kinds of fontanels in infants: two of them are symmetrical on each side of the skull, the sphenoid and mastoid fontanel. Another called the lambda or posterior fontanel, closes quickly in the first two months of life. And the last, called the bregma or anterior fontanel closes later, between one and a half and three years of age, and is useful for judging hypertension
in the skull or assessing the state of dehydration.