Which pharyngeal arch is also known as the mandibular arch?

• A. First pharyngeal arch.
• B. Second pharyngeal arch.
• C. Third pharyngeal arch.
• D. Fourth pharyngeal arch.

Answer: (A)

The first pharyngeal arch is the mandibular arch because it forms the structures of the lower jaw. In early development this arch creates the mandibular and maxillary prominences, with the mandibular prominence giving rise to the mandible itself. It also contributes to the middle ear bones (malleus and incus) via Meckel’s cartilage and to the muscles of mastication and other associated muscles. The innervation for these tissues comes from the mandibular division of the trigeminal nerve (V3). The other arches build different parts of the face and neck (for example, the second arch forms hyoid-related structures with the facial nerve; the third with hyoid and stylopharyngeus via IX; the fourth with laryngeal cartilages via X), so they are not the mandibular arch.