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Shaping of functional and morphological asymmetry in five to thirty months old children
1Department of Biology, Academy of Physical Education, Katowice, Poland.
Insights
This study on children
Area of Science:
- Developmental Pediatrics
- Human Morphology
- Motor Control
Background:
- Hand functional differentiation is crucial for development.
- Morphological asymmetry and upper limb lateralization are key aspects of child development.
- Understanding these developmental trajectories informs early intervention strategies.
Purpose of the Study:
- To investigate the development of hand functional differentiation and upper limb lateralization in young children.
- To analyze morphological asymmetry in relation to hand dominance.
- To identify age-related patterns and sex differences in lateralization.
Main Methods:
- Utilized tests by Franus, Spionek, and Szuman to assess hand functional differentiation.
- Measured morphological asymmetry using arm circumference, arm epiphysis width, stylion width, and hand thickness.
- Calculated somatic indices and the asymmetry index (Wolański).
Main Results:
- Upper limb lateralization degree increases with age.
- A temporary decrease in lateralized individuals and increase in bimanual individuals observed in girls (21-25 months) and boys (25-30 months).
- Right-handedness often correlates with specific right limb morphological traits (larger arm circumference, smaller forearm circumference, hand thickness).
Conclusions:
- Hand functional differentiation and upper limb lateralization show distinct developmental patterns in early childhood.
- Age and sex influence the progression of lateralization and bimanuality.
- Morphological asymmetry provides insights into the underlying physical basis of handedness.
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.