Full Infant Skull and Fontanelles (Lateral View) Description
[Continued from above] . . . separation of plates making up the skull. With this comes an element of malleability resulting in the infant skull's temporary image of the mother's pelvic opening. Equally noticeable is the soft spot at the top of the skull, which will remain until the plates grow together.
The anterior fontanelle and posterior fontanelle are the two areas of an infant's head where the skull bones have not completely covered the brain. The anterior fontanelle is located towards the front of the head. The posterior fontanelle is located at the upper back part of the head. The posterior fontanelle is no longer obvious when the infant is four months old. The anterior fontanelle can normally be felt until 9-16 months of age.
Eventually the fontanelles close as the cranial bones grow together. The posterior fontanelle usually closes about two months after birth; the sphenoid fontanelle closes at about three months, the mastoid fontanelle closes near the end of the first year, but the anterior one may not close until the middle or end of the second year.