Chapter 2. Prehension

Chapter 1 - Introduction 5
Figure 1.1 Examples of prehension, using the hand alone and with
a tool. Without a screwdriver, one might use the thumb and index
finger to turn a screw. As the screw head gets close to the sur-
face, the index fingernail is inserted for the last few turns. When
a screwdriver is handy, it is grasped in a way to tighten a screw.
Note the different, functional hand postures used for grasping the
same screwdriver to open a paint can or mix the paint.