The applet provides three forms of control for navigating within the Visible Human. By clicking on the buttons (1), you can select a standard slice orientation (axial, sagittal, coronal). By clicking and dragging either on the small 3D model (2) or on the currently displayed slice (3), you can move as illustrated on the figure below.
When using the left mouse button on the miniature 3D model, the slice follows the mouse cursor position. When interacting on the displayed slice, translations and rotations are carried out relatively to the current slice position and orientation.
Cool tool for human anatomy, at Visible Human Server
Thanks David Rothman