The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)

Variability in bone length and proportions of the arm and hand


Department of Sociology and Anthropology, North Carolina State University

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Traditionally, investigations of proportion in the limbs examine proximal and distal length differences by comparing brachial and crural indices. This approach, however, has only considered the bones of the arm or leg, and does not investigate variability throughout the entire limb. Do all the long bones of the limb decrease in stability proximo-distally, or is there a break between the patterns of variability in the arm versus those in the hand?

Bias-adjusted coefficients of variation were determined for the length of each long bone in the left arm and hand of 106 individuals. The variation of individual bones were compared, with the sum of the MC3, PP3, IP3, and DP3 lengths as a proxy for hand length (ray 3) to examine relationships throughout the entire limb. Significant differences were noted when a coefficient of variability diverged 3% or more from those of the adjacent bones. In males, the pattern of proximo-distal variability in the arm halts at the distal radius, then repeats again in the bones of the hand - the metacarpals are more stable than the radius and ulna. Females demonstrated a general proximo-distal decrease in stability throughout the entire arm, with no repeated pattern in the hands. Also, differences between rays 2-4 compared to rays 1 and 5 in both sexes support expected patterns developmental field division in the hand.

These findings may help uncover further developmental patterns evidenced in human arms and hands, allowing researchers a better understanding of limb proportion, health, and stress.

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