The core of each branchial arches is derived from mesoderm and Neural crest cells.
The pharyngeal arches initially have identical structures :-
• Surface ectoderm on the outside
• Mesenchymal core derived from mesoderm
• Endoderm derived epithelium on the inside .
:: the Mesoderm of the pharyngeal arch is derived from paraxial mesoderm and lateral plate mesoderm.
This is invaded by neural crest cells that contribute to the formation of skeletal elements and connective tissues of the head and neck region.