Age-Related Bone Brittleness (IMAGE) DOE/Lawrence Berkeley National Laboratory Caption At each size scale, the hierarchical structure of human cortical bone influences its susceptibility to fracturing with smaller levels affecting intrinsic toughness and higher levels impacting extrinsic toughness. Credit Image courtesy of Ritchie, et. al Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.