Why is your skull immovable joints are not fused together until after birth?

The skull of a newborn baby is not completely immovable, and the joints between the skull bones are not fused together until after birth. This is because the baby's head needs to be able to grow and expand rapidly during the first few months of life. The fontanelles, which are the soft spots on the baby's head, allow the skull to grow and expand without causing any damage to the brain.

As the baby grows, the fontanelles gradually close and the skull bones fuse together. This process is usually complete by the time the child is about 2 years old. The fusion of the skull bones helps to protect the brain from injury and provides support for the face and neck.

Here are some of the reasons why the skull is immovable at birth but the joints are not fused together:

* To allow for brain growth: The brain of a newborn baby is about 25% of its adult size. Over the course of the first few months of life, the brain grows rapidly, increasing in size by about 1% per day. The fontanelles allow the skull to expand to accommodate this growth.

* To allow for childbirth: The baby's head needs to be able to compress slightly in order to fit through the birth canal. The fontanelles allow the skull to compress without causing any damage to the brain.

* To protect the brain: The fontanelles help to protect the brain from injury. If the baby's head is hit, the fontanelles can absorb the impact and help to prevent the brain from being damaged.

The fusion of the skull bones is a gradual process that occurs over the course of the first few years of life. This process is essential for protecting the brain and providing support for the face and neck.