[Ontogeny of the jaw].

Four pairs of branchial arch appear apparently in the neck region of human embryo about 32 days after fertilization. Maxillary prominence of the first branchial arch gives rise to the maxilla and zygomatic bone etc., and mandibular prominence forms the mandible and so on. Muscles for mastication are also derived from 1st branchial arch, into which fifth cranial nerves grow from the brain. Thus, human embryo improves the 1st branchial arches into the upper and lower jaws, and forms digestive organs needed for intake, mastication, and swallowing of foods. Finally they develop the brain for integral treatment of sensory information from eyes, tongue, nose, and ears.