Cineradiographic study of forelimb movements during quadrupedal walking inthe brown lemur (Eulemur fulvus, Primates : Lemuridae)

Movements of forelimb joints and segments during walking in the brown lemur (Eulemur fulvus) were analyzed using cineradiography (150 frames/sec). Met ric gait parameters, forelimb kinematics, and intralimb coordination are de scribed. Calculation of contribution of segment displacements to stance pro pulsion shows that scapular retroversion in a fulcrum near the vertebral bo rder causes more than 60% of propulsion. The contribution by the shoulder j oint is 30%, elbow joint 5%, and wrist joint 1% Correlation analysis was ap plied to reveal the interdependency between metric and kinematic parameters . Only the effective angular movement of the elbow joint during stance is s peed-dependent. Movements of all other forelimb joints and segments are ind ependent of speed and influence, mainly, linear gait parameters (stride len gth, stance length). Perhaps the most important result is the hitherto unkn own and unexpected degree of scapular mobility. Scapular movements consist of ante-/retroversion, adduction/abduction, and scapular rotation about the longitudinal axis. Inside rotation of the scapula (60 degrees-70 degrees), together with flexion in the shoulder joint, mediates abduction of the hum erus, which is not achieved in the shoulder joint, and is therefore strikin gly different from humeral abduction in man. Movements of the shoulder join t are restricted to flexion and extension. At touch down, the shoulder join t of the brown lemur is more extended compared to that of other small mamma ls. The relatively long humerus and forearm, characteristic for primates, a re thus effectively converted into stride length. Observed asymmetries in m etric and kinematic behavior of the left and right forelimb are caused by a n unequal lateral bending of the spinal column. (C) 2000 Wiley-Liss, Inc.