Development of the human external ear.

External ear development is a lengthy and complex process that extends from early embryonic life until well into the postnatal period. Initial development of the auricle and external auditory canal during the fourth and fifth weeks of gestation is closely associated with anatomical changes involving the pharyngeal arch apparatus of the human embryo. The auricle and external canal are well formed by the time of birth but do not attain their full size and adult configuration until about 9 years of age. Sebaceous and modified apocrine glands, which are responsible for cerumen production, begin their development at about 5 months gestation in association with hair follicles in the outer portion of the external canal. Although they appear anatomically mature before birth, these glands do not reach full functional capacity until puberty.