Meeting Abstract

P3.64  Tuesday, Jan. 6  Bending regimes of capuchin limb bones DEMES, B.*; CARLSON, K.J.; Stony Brook University; New York College of Osteopathic MedicineBending regimes of capuchin limb bones bdemes@ms.cc.sunysb.edu

Capuchin monkeys, like many other primates, have a highly versatile locomotor repertoire. We investigated how locomotor versatility influences the loading regimes of distal limb bones by documenting substrate reaction forces (SRF) and 3D limb postures for capuchins moving on a flat substrate (terrestrial), on an elevated pole (arboreal), and performing turns. The SRF vector forms discrepant angles with the forearm and leg, indicating that they are loaded in bending. The bending axes are not in principal anatomical planes but at oblique angles, and frontal plane bending is a major component of the overall bending regime. The bending moments are higher for the leg than for the forearm. The discrepancy angles between the limb segments and the SRF vectors are more variable in simulated arboreal locomotion than in overground locomotion. This confirms the notion that arboreal locomotion is associated with greater variation in long bone loading than terrestrial locomotion. Directional changes of about 30 degrees are also associated with discrepancy angles that vary in orientation. Even at the moderate level of locomotor variation simulated in the lab, bending regimes were found to be variable. Most primate long bone shafts do not have highly biased cross sections that preferentially reinforce one plane, and are therefore well-suited to withstand variable bending regimes. Supported by NSF BCS 0548892