The bones of the newborn skull are not fully ossified and are separated by large areas called fontanelles, which are filled with fibrous connective tissue. The fontanelles allow for continued growth of the skull after birth.Click to see full answer. Accordingly, how do skull bones ossify?The skull is a complex structure; its bones are formed both by intramembranous and endochondral ossification. The endocranium, the bones supporting the brain (the occipital, sphenoid, and ethmoid) are largely formed by endochondral ossification. Thus frontal and parietal bones are purely membranous.Beside above, how many Fontanels does a fetal skull have? 2 fontanelles Also, at what age is your skull fully formed? 20 What is the weakest part of the skull?The pterion is known as the weakest part of the skull. The anterior division of the middle meningeal artery runs underneath the pterion. Consequently, a traumatic blow to the pterion may rupture the middle meningeal artery causing an epidural haematoma.