fontanelle

/ˌfɒntəˈnɛl/

Other forms: fontanelles

A fontanelle is the soft spot on a baby's head where the skull bones haven't finished growing and fusing together. Even though the fontanelle seems delicate, it's actually quite sturdy and protective.

The fontanelle allows a newborn baby's brain to continue growing, while the skull expands more slowly. It also means the bones of the skull can flex a bit when the baby is born — in other words, it can compress as it's squeezed through the birth canal without damaging the baby's head. As babies grow, the fontanelle begins to close. The Old French root of fontanelle, fontaine, means "hollow in the earth where a spring arises."

Definitions of fontanelle

1. noun

   any membranous gap between the bones of the cranium in an infant or fetus
   synonyms: fontanel, soft spot

   types:

   anterior fontanelle

   corresponds to the bregma when bones have ossified

   sphenoid fontanel, sphenoid fontanelle, sphenoidal fontanel, sphenoidal fontanelle

   the irregularly shaped area on either side of the cranium where the frontal bone and the anterior tip of the parietal bone and the temporal bone and the greater wing of the sphenoid bone meet; corresponds to the pterion when bones have ossified

   type of:

   opening, orifice, porta

   an aperture or hole that opens into a bodily cavity