Large fontanelles

What it means

In newborns, the two frontal bones, two parietal bones, and one occipital bone are joined by fibrous sutures, which form a small posterior fontanelle, and a larger, diamond-shaped anterior fontanelle. These regions allow for the skull to pass the birth canal and for later growth. The fontanelles gradually ossify, whereby the posterior fontanelle usually closes by eight weeks and the anterior fontanelle by the 9th to 16th month of age. Large fontanelles are diagnosed if the fontanelles are larger than age-dependent norms.

There are six membrane-covered openings between the cranial sutures in the incompletely ossified skull of the fetus or newborn infant that normally close sometime after birth (anterior fontanel, cranial fontanel, mastoid fontanel, posterior fontanel, sphenoidal fontanel).

Rare diseases that can present with this49

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Enlarged fontanelles · Large bregma sutures · Large fontanel · Large fontanelle · Large fontanels · Large, late-closing fontanelle · Persistent wide fontanel · Wide bregma sutures