Atresia of the external auditory meatus is by no means uncommon. Unfortunately, in some cases it remains unrecognized, while others fail to find their way into the literature.
On the basis of the etiologic factors, atresia is grossly classified as congenital or acquired. The abnormal embryologic events responsible for congenital atresia have been discussed in detail in the splendid work of Lyman Richards.
According to Richards,1 the outer ear develops in a peculiar manner. It begins as a pitlike indentation of the external cutaneous surface in the region of the future auricle. The pit extends inward for a short distance in the direction of the first gill cleft. From its inner end a solid cord of ectoderm extends inward and becomes expanded medially into a disklike plate, lying on an oblique plane just outside the cavity of the middle ear. The next process is canalization from within outward of the