overlaps overlaps pharyngeal arch 2 pharyngeal arch 1 1st arch pharyngeal cleft branchial groove of 1st arch EHDAA:575 VHOG:0000969 1st pharyngeal cleft EHDAA2:0000009 A groove that is situated between the 1st and 2nd pharyngeal arch. UBERON:0005872 In all jawed vertebrates the first arch forms the jaw, while the second arch forms the hyoid apparatus. These two arches are separated by the first pharyngeal pouch and cleft.[well established][VHOG] 1st pharyngeal groove 1st arch branchial groove 1st branchial cleft 1st arch groove ectoderm EMAPA:16119 1st pharyngeal groove ectoderm VHOG:0000554 pharyngeal cleft