Final answer:
The three major parts of the fetal skull are the frontal bone, the parietal bones, and the occipital bone, which form the cranium, protecting the brain and allowing growth and development both during and after birth.
Step-by-step explanation:
The Three Major Parts of the Fetal Skull:
The human fetal skull comprises several bones that are significant for both birth and the growth of the brain. The three major parts of the fetal skull include the frontal bone, the parietal bones, and the occipital bone. These bones form through a process called intramembranous ossification, where mesenchymal cells differentiate directly into bone-producing cells. These bones are separated by areas of dense connective tissue called fontanelles, which are soft spots that allow the skull to change shape during birth and grow with the brain after birth. The largest fontanelle is located at the junction of the frontal and parietal bones. The skull begins to fuse together with fibrous connective tissue, at sutures such as the sagittal suture, the coronal suture, the squamous suture, and the lamboid suture, as the child matures.
Additionally, the cranial cavity formed by the cranial bones including the sphenoid and ethmoid bones, encloses and protects the brain. The ethmoid bone plays a crucial role in separating the nasal cavity from the brain, while the sphenoid bone contributes to forming the eye sockets.