Keys, at least in Version 7 and under, were used to move through a figure's hierarchy.  If the right shoulder were selected the down arrow is supposed to select the figures right forearm, the up area moves the selection to the figure's right collar.

Not sure this always works though and don't really know why.

I usually use the dials to translate/rotate and the drop down menus on the Parameter Dials menu to select body parts.  If the scene is not too complicated using the mouse sometimes to select body parts.