I’ve recently learned that babies are really good at dealing with broken bones because their bones are similar to cartilage. How do they form into “adult bones”, and how long does that process take?

Question

IIRC babies have like 300 bones at birth, and that number gets closer to 200 with age. How do the bones fuse (I hope that’s the right term) together, and when does this process generally stop?

In: Biology

Answer 1

Yes, the correct term is bone fusion. Essentially baby bones function a lot like a “broken” bone in that the cells add extra calcium as they grow, hardening them. And if you’ve ever heard the term “growth plates” those are pieces found on the ends of long bones (the bones in your arms and legs) that fuse to help lengthen a bone as a child grows, so if one is damaged in an injury, abnormal growth of a limb can occur if the injury isn’t treated properly. Skulls are made up of many plates that fuse together as a child grows as well. Their heads actually need to be quite “squishy” to fit through the birth canal. The whole process of fusion/no further growth in height generally coincides with puberty. Bones continue fusing as a person ages, which is why the fusion lines on a 90 year old’s skull are barely visible, but on a 20 year old’s are solid, but highly visible.