Cineradiographic study of forelimb movements during quadrupedal walking in the brown lemur (Eulemur fulvus, primates: Lemuridae)

Abstract

Movements of forelimb joints and segments during walking in the brown lemur (Eulemur fulvus) were analyzed using cineradiography (150 frames/sec). Metric gait parameters, forelimb kinematics, and intralimb coordination are described. Calculation of contribution of segment displacements to stance propulsion shows that scapular retroversion in a fulcrum near the vertebral border causes more than 60% of propulsion. The contribution by the shoulder joint is 30%, elbow joint 5%, and wrist joint 1%. Correlation analysis was applied to reveal the interdependency between metric and kinematic parameters. Only the effective angular movement of the elbow joint during stance is speed-dependent. Movements of all other forelimb joints and segments are independent of speed and influence, mainly, linear gait parameters (stride length, stance length). Perhaps the most important result is the hitherto unknown 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 humerus, which is not achieved in the shoulder joint, and is therefore strikingly different from humeral abduction in man. Movements of the shoulder joint are restricted to flexion and extension. At touch down, the shoulder joint of the brown lemur is more extended compared to that of other small mammals. The relatively long humerus and forearm, characteristic for primates, are thus effectively converted into stride length. Observed asymmetries in metric and kinematic behavior of the left and right forelimb are caused by an unequal lateral bending of the spinal column.

Arboreal locomotion in rats – the challenge of maintaining stability

“…This position allowed them to generate the medially directed pressure that is necessary to avoid slipping. Observations, still images and drawings from previous studies support the assumption that this strategy is not restricted to mammals lacking grasping extremities [p. 271 in Carlson et al ; p. 444 in Schmitt (Schmitt, 1994); p. 254 in Schmidt (Schmidt, 2000); p. 4326 in Lammers and Biknevicius (Lammers and Biknevicius, 2004); p. 6 in Schmidt (Schmidt, 2005)]. The hindlimbs, however, are positioned in a medial direction and towards the sides rather than the top of the branch (Fig.6).…”

“…Demes et al, 1994;Larson et al, 2000;Schmitt, 2003c;Schmidt, 2005;Hanna et al, 2006;Schmidt, 2008;Larson and Stern, 2009). Despite the appearance of greater arm protraction during small branch locomotion, the limbs of primates typically undergo a deep flexion (crouched posture) to lower the center of mass (Schmitt, 1994;Schmitt, 2003c;Franz et al, 2005).dependent on the diameter of support (Schmidt and Fischer, 2000;Shapiro et al, 2001;Schmidt, 2005). These authors propose that lateral rotations of the torso play a major role in increasing stride length and discuss it in terms of the evolution of primates.…”

Hind limb proportions and kinematics: are small primates different from other small mammals?

“…Segment abduction angles were approximated from the foreshortening of the bones in the parasagittal projection. The methods of collecting and processing kinematic variables from cineradiographs have been described elsewhere in detail (Schmidt and Fischer, 2000;Schmidt, 2005) and will be summarised only briefly here. The x-ray equipment consists of an automatic Phillips ® unit with one x-ray source that applies pulsed x-ray shots (Institut für den Wissenschaftlichen Film, Göttingen, Germany).…”

Ontogenetic development of locomotion in small mammals - a kinematic study

“…Joint movements vary from species to species. Cercopithecus aethiops showed monophasic shoulder joint movements (Whitehead and Larson, 1994) while Felis catus f. domestica (English, 1978;Boczek-Funcke et al, 1996) and Eulemur fulvus (Schmidt and Fischer, 2000) exhibit biphasic joint behaviour during symmetrical gaits. In Tupaia glis, shoulder joint movements depended on gait .…”

“…No major changes in overall limb performance were observed during postnatal ontogeny. Segmental and joint movements of adults of different mammalian species began at the end of stance or swing phase shortly before touch-down or lift-off and lasted continuously into the next phase (Fischer, 1994;Fischer and Lehmann, 1998;Schmidt and Fischer, 2000;Fischer et al, 2002). The onset of protraction and retraction was not coupled to the events of touch-down and lift-off.…”