start stage end stage pharyngeal arch pharyngeal arch 1 ZFA:0001612 mandibular arch zebrafish_anatomy TAO:0001595 The first pharyngeal arch, also known as the mandibular arch, forms the jaw. The first pharyngeal arch gives rise to elements of the jaw, with the most anteriorly positioned cranial neural crest cells contributing to mandibular arch structures, including Meckel's and palatoquadrate cartilages that constitute the lower and upper jaw respectively. visceral arch 1 segmentation:10-13 somites adult