At what age is your skull fully formed? --- Marko, Zagreb, Croatia
Marshall Brain Answers:
The following video shows the bones of the skull, and early on it talks about the "sutures" that hold the bones together:
When a baby is born, these sutures have not fused and there are gaps between the skull bones called fontanelles. At the top of the skull there is a fairly large soft spot where no bone is protecting a baby's brain. People are a little freaked out by this sometimes, because you can see the blood pulsing in that soft spot, like this:
One reason for these gaps and soft spots is so that the baby's head can squeeze through the limited space in the birth canal. Another is the fact that the skull grows a lot during the first year to accommodate the enlarging brain. Usually the skull bones fuse together and the soft spots fill in between the first and second birthday.
More info: Excessively Large Fontanelles and Skull Of A Newborn Image