Does position sense at the elbow reflect a sense of elbow joint angle or one of limb orientation?

The question is addressed of whether position sense at the elbow joint is best described as a sense of the elbow joint angle or as a sense of the orientation of the limb, limb orientation being defined as the angle the forearm makes with the vertical. When the upper arm is vertical, these two measures are equivalent; however, in the more general case of non-zero angles of forward flexion at the shoulder, they differ. Subjects were asked to match either joint angles or limb orientation of their two arms. It was found that the error in matching limb orientation was significantly smaller and that it was unaffected by an inequality in the loading on the two arms.