Skull

Development of the cranium is preceded by that of the meninges, in particular, the periostal layer of the dura mater.
The material for the formation of the skull comes from the paraxial mesoderm, the neural crest and the occipital somites. In addition, it is thought to come from the prechordal plate. It is possible to distinguish two cranial parts: the brain case (neurocranium) and the facial cranium (viscerocranium or splanchnocranium). In addition, it is possible to subdivide the skull into a base and a vault. The base of the skull, the chondrocranium, forms first as cartilage (endochondral ossification), like the vertebral column. It ossifies later on during development. The vault develops mainly through intramembranous ossification (desmocranium). The viscerocranium forms mainly from the cartilaginous primordia of the first two pharyngeal arches. This cartilaginous skeleton is subsequently completed and additionally partly replaced by bones of intramembranous ossification (the maxillary and mandibular processes of the first pharyngeal arch).