Curriculum Module
Axial Skeleton Development
The axial skeleton forms the skull, vertebral column, ribs, and sternum. It develops from paraxial mesoderm (somites), lateral plate mesoderm, and neural crest cells through both intramembranous and endochondral ossification.
Viscerocranium
The facial skeleton emerges primarily from the first two pharyngeal arches. The first arch generates the Maxillary Process, and the mandibular process containing Meckel Cartilage.
Mesenchyme condenses around Meckel cartilage to form the Mandible via intramembranous ossification. The dorsal tips of arches 1 and 2 also give rise to the three middle ear bones: Malleus, Incus, Stapes. The initial newborn face is small due to absent paranasal sinuses and unerupted teeth.
Key Insight
This stage is critical for embryonic support structures and establishes the main body axis.