The incidence of auricular malformation is a very common congenital malformation of the children’s maxillofacial region except for cleft lip and palate, and many parents of the affected children would like to know the causes and types of its occurrence, and here to popularize the basic knowledge of auricular malformation: The formation of the auricle The auricle is originated from the first gill arches of the embryo (the mandibular arch) and the second gill arches (the hyoidal arch). In the 5th week of the embryo, a portion of the gill arch will develop into the auricle, and the auricle develops roughly in the 5th to 9th week of the embryo. In embryonic week 6, ectoderm and mesenchyme are activated and proliferate in the mandibular and hyoid arches to form six hillock-like elevations, with hillocks 1, 2, and 3 appearing caudal to the mandibular arch and later forming the auricular screen, the foot of the auricle, and the upper portion of the external auricle, and hillocks 4, 5, and 6 appearing at the head of the hyoid arch and developing into the para-auricular whorl, the paired auricle, the paired auricle screen, and the earlobe. the six hillock-like elevations proliferate and fuse to form the auricle, and the first gill cleft depresses inward to form the external auricle. The first gill cleft is concave inward to form the external auditory canal. Causes of auricular malformation During the developmental stage of the auricle, the embryo is affected by genetic or external factors (e.g. viral infection, pregnant women taking certain drugs or suffering from metabolic and endocrine disorders, or exposure to certain chemical substances and radiation, etc.), and is susceptible to a variety of developmental malformations of the auricle.