The skull develops from the mesenchyme around the developing brain. It can be divided into the neurocranium, a protective case around the brain, and the viscerocranium which forms the skeleton of the face.
The membranous neurocranium develops by mebranous ossification from the mesenchyme surrounding the sides and roof of the brain.

The cartilaginous neurocranium develops by endochondral ossification from the cartilaginous skull base which fuses with several surrounding cartilages.
The viscerocranium is formed mainly by the cartilages of the first two pharyngeal arches (Meckel's and Reichert's cartilages).