Asymmetry of the Upper Extremity in Contemporary Czech Children - Skvarilova - 1999

Asymmetries in the body shape are, within a certain range, a physiological phenomenon that reflects genetic and exogenous influences during the development of the individual. The A. investigates the development of asymmetries in the upper extremity in relation to age and sex, to differentiate fluctuating and directional asymmetry and to define the borderlines of physiological and non-physiological asymmetries in different traits. Asymmetries of the upper extremities were analyzed in 1,002 children from Prague, Czech Republic, aged 6-18 years. The length of the upper extremity upper arm, forearm and hand, circumference of the arm, forearm and wrist and width of the epiphysis of the humerus, wrist and hand were assessed. Left-handed subjects were excluded from the study. The results revealed that the degree of asymmetries of the upper extremity is equal in both sexes and does not change substantially with age (absolute asymmetry increases in direct relation to the growth of the trait). With regard to the size of the traits, the asymmetries of the upper extremity are markedly smaller than previously evaluated facial asymmetries (Škvařilová 1993); this applies in particular to length parameters. This may be the result of phylogenetic selection directed against asymmetry of the locomotor system. Asymmetries of the upper extremity are of the directional rather than fluctuating type, in particular in adult men, in whom there is an obvious developmental trend from fluctuating to directional asymmetries. These findings concerning the dominance of the right hand are associated with the effect of function and functional laterality. There is also an indication of a certain lateral compensation between the length of the upper arm and the lower segments of the extremity. The doubled value of standard deviations of signed asymmetry was used to define the range of physiological asymmetrv as 4 mm for length and circumferential (except the wrist) parameters of the upper extremity, 3 mm for the circumference of the wrist and 2 mm for the width variables of the extremity. The suggested range does not depend on age and sex, but in directional asymmetries it is important to make a correction in favour of the dominating side (as a rule by 0.5-1 mm). The definition of the range of physiological and non-physiological asymmetry may be of practical importance in a number of medical disciplines.

Keywords

Upper extremity - Fluctuating and directional asymmetry - Absolute and relative asymmetry - Range of physiological asymmetry

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