Which cells form the skeletal components of the pharyngeal arches?

• A. Neural Crest Cells
• B. Paraxial Mesoderm
• C. Endoderm
• D. Ectoderm

Answer: (A)

Cranial neural crest cells drive the formation of the skeletal framework of the pharyngeal arches. These cells originate at the border of the neural tube and migrate into the arches, where they condense into mesenchyme and later differentiate into cartilage and bone that shape the facial and neck skeleton. Classic examples include Meckel’s cartilage in the first arch and Reichert’s cartilage in the second arch, which contribute to facial bones and middle-ear structures. Endoderm lines the pharyngeal pouches inside the arches, and ectoderm covers the outside, while paraxial mesoderm largely provides muscle precursors and contributes to some skull elements but does not form the primary arch cartilage. So the neural crest–derived mesenchyme is responsible for the skeletal components.