I've seen this image (or variants on it) pop up in quite a lot of places, and it appears to be part of quite a few clip art collections, but it seems like an oddly specific thing to be clip art. Is there any history behind the image?
The manicule, or pointing hand, is a visual device to highlight the important parts of a text. It has a long history in medieval manuscript illumination, where it could be interpreted as the presence of the scribe's hand in a hand-written book. (I.e the monk who copied the book is trying to show you what he feels is important about it.)
This article from "The Architectures of the Book" project at the University of Saskatchewan explains the history and significance better than I can: http://drc.usask.ca/projects/archbook/manicules.php
*edit: medical to medieval. Damn autocorrect.
