Fig. 10.

Dependence of torque direction (ALPHA and BETA) on the angles defining arm posture (ROT (ζ), AZ (η),EL (θ)) for the body-fixed frame of reference. Data from the AD of Subject C are shown; these are the same data that appear (in the arm-fixed frame of reference) in the extreme left plots of Figure 5. For the scatterplots, α is the angle in the M_x′/M_y′plane, relative to the -M_x′(ABD)-axis, and β is the angle relative to theM_x′/M_y′ plane. Negative values of humeral rotation indicate external rotation; positive values indicate internal rotation.