Anthropometry in ethnic groups and cultural and geographical diversity auricular anthropometry of newborns: Ethnic variations

Abstract

The human ear is important not just for its aesthetic value and hearing ability, but also helps to confer normality to a newborn. Developmental abnormalities can result in abnormal ear shape and size. Descriptive examination must therefore be supplemented by objective anthropometric measurements, to aid a complete diagnosis profile. Ethnic and race variations are well known to have an impact on various anthropometric measurements. The ear is likely to be no different. However, comparisons of ear measurements in different ethnic groups have been difficult and rarely carried out. Differences in methodologies and definitions have also made comparisons of reported studies challenging. Nevertheless, just as gestation is an important consideration when making such measurements, so is the ethnicity of the baby. Ear length by convention is most often defined as the maximum length measured from the superior to the inferior aspect of the external ear. By and large, the Caucasian ear appears to have a marginal edge on the Asian ear, with the Israeli and Turkish babies registering the longest ears. The impact of even minor differences in ethnicity is further realized in seeing that even Chinese of different historical roots may have different measurements, with the Hong Kong Chinese ear being somewhat smaller than the Taiwanese and Singaporean Chinese ear. Also interestingly, the longest ear need not necessarily be the widest ear. Ear width is defined as the transverse distance from the palpable anterior base of the tragus through the external auditory canal to the margin of the helical rim at the widest point. For this, the Japanese ear is supreme. Another aspect would be the placement of the ear which changes as the child grows. The few studies that evaluated this aspect of the ear concurred that it was normal to have at least a third of the ear above the intercathial medial line across the eyes, with the Asian ear appearing to be somewhat higher placed than the Caucasian ear. Knowing the size, shape and position of the normal ear lends more weight to terms such as microtia (small ear), macrotia and low-set ears, allowing the practicing clinician to pinpoint abnormalities and effect investigations and interventions more accurately, reducing unneeded parental anxiety.