Pharyngeal arches are one of the four key synapomorphies of the phylum chordata, along with a post-anal muscular tail, notochord, and dorsal hollow nerve chord. Pharyngeal arches develop into the branchial arches of gills in fish, but in humans, they take a different route - five of the six develop into the bones, cartilage, and muscles in our jaws.

• First Arch: “Mandibular arch;” gives rise to the mandible and maxilla, as well as the muscles of mastication and trigeminal nerve
• Second Arch: “Hyoid arch;” gives rise to the hyoid bone (lesser horn) and artery, facial nerves, and muscles of facial expression
• Third Arch: Stylopharyngeus muscle, hyoid (greater horn), glossopharyngeal nerve, and carotid arteries
• Fourth Arch: Muscles of the soft palate, the cricothyroid muscle, thyroid and epiglottic cartilage, the vagus nerve, subclavian arteries and aortic arch.
• Fifth Arch: no human structures develop
• Sixth Arch: Muscles of the larynx, the recurrent laryngeal nerve, pulmonary artery, and ductus arteriosus

Photo Credit: RemakeHealth