Retra

Filenames: diproa, retra

These three dimensional animations are to facilitate visualization of hindlimb movements of vertebrates with "sprawling" limb posture. This model of a lizard hindlimb uses boxes to represent the pelvis and foot and cylinders to represent the femur and lower leg. The rectangular process on the ventral surface of the proximal "femur" represents the greater trochanter which forms the proximal insertion of the caudofemoralis muscle. On the distal end of the "femur" I have placed a vertical line in the same plane with trochanter of the femur to help visualize femur rotation.

Because the knee is lateral to the hip for most lizards and salamanders, some terminology for limb movements differs from that used for humans and other mammals. Furthermore, the following three propulsive movements that characterize limbed locmotion of most ectothermic vertebrates are lacking or relatively unimportant for propelling endothermic vertebrates.

(file diproa) is rotation of the femur about its long axis. In our work an increase in the magnitude of this angle indicates clockwise movement and a decrease in magnitude indicates a counter-clockwise movement as seen in a right lateral view.

(file retra) are two-dimensional movements that are measured from a dorsal perspective by quantifying the angle between the femur and the mid-saggital plane through the pelvis. The protraction and retraction angles in the animation are from a Dipsosaurus dorsalis moving at 74 cm/s on a horizontal treadmill.

(file reropr) occur simultaneously in most lizards and salamanders. This animation shows how a limb would move if these were the only three movements and the knee and ankle angles were constant (90 degrees). Pelvic rotation, femur retraction and rotation angles were taken from a Dipsosaurus dorsalis moving at 74 cm/s on a horizontal treadmill.