Asymmetry in the length of human humerus and radius during ontogeny.

Bilateral body structures usually present some kind of asymmetry. In humans, long bones are suitable to study asymmetries because they are subject to different stimulus that can influence their development and shape. This study focuses on asymmetries of humerus and radius length during ontogeny, with a sample of 1,421 people from Barcelona ranging in age from 0 to 22 years. Data were obtained from dual-energy X-ray absorptiometry images. The humerus results showed the existence of significant directional asymmetry to the left in neonates that progressively turns to right through ontogeny, being significant in people from 11 to 16 years. The radius results are not so evident, but it can be deduced directional asymmetry in children and adolescents, with little delay from humerus. Regarding fluctuating asymmetry, higher values have been seen in neonates and they decrease during ontogeny.