Final answer:
The cranial vault is formed by intramembranous ossification, while the cranial base undergoes endochondral ossification.
Step-by-step explanation:
The bones of the cranium are formed through one of two processes: intramembranous ossification or endochondral ossification. The cranial vault, which includes the flat bones of the skull, develops via intramembranous ossification. This process involves the direct conversion of embryonic mesenchymal tissue into bone, which begins in utero and continues into adolescence. The cranial base is formed through endochondral ossification, where mesenchymal tissue first forms a hyaline cartilage model, which is later replaced by bone. This method is also used for the development of long bones and takes considerably longer than intramembranous ossification.