Fontanelles

Baby’s skulls are amazing. When you are born, your skull is actually separated into a bunch of different skull bones with pliable stretchy parts between them to allow for a few things. One, to be able to squeeze that noggin through the birth canal, the skull plates need to be mobile and be able to morph into a shape to fit through the birth canal. The other reason is that baby’s brain is developing and growing so rapidly, we need the skull to be able to stretch and grow rapidly as well over the first 12-18 months. Hence, we have these stretchy soft parts called fontanelles. 

There is a big one in the front and a smaller one in the back when baby is first born. The smaller one in the back often turns to bone at around 3-6 months of age. The larger anterior fontanelle usually closes around 12-18 months of age. 

Now these squishy parts of the head are crazy. If we have a baby with a fever, is crying, or who is very well hydrated, we can often see this area bulge a little bit and pulsate. If we have a kiddo who is a little dehydrated in the setting of a stomach bug with diarrhea and vomiting, this can actually sink in. It is often a spot that older siblings like to touch and poke, cuz I mean it is weird and squishy. But don’t worry, the membrane here is very tough and can handle a few gentle pokes here and there from inquisitive siblings.