Shaping of functional and morphological asymmetry in five to thirty months old children.

Abstract

Studies of 175 children in Katowice day nurseries were conducted. Functional differentiation of hands was determined by means of tests worked out by Franus, Spionek and Szuman. Morphological asymmetry was pronounced as based on the greatest value of arm circumference, the width of arm epiphysis, stylion width and hand thickness. Somatic indices, as well as asymmetry index according to Wolański were defined on the basis of values achieved. The analysis of data shows that the degree of upper limb lateralization increases along with age. Temporary decrease of the number of lateralized individuals--and coincident increase of bimanual ones--was observed in girls at the age of 21-25 months, as well as in 25-30 months old boys. Right--handedness is most commonly accompanied--though not on statistically significant level--by domination of the following right limb traits: the biggest arm circumference, the smallest forearm circumference and hand thickness.