Certain areas of the body contain structures that are difficult to envision in their proper spatial orientations and whose functions are complex and difficult to grasp. This is especially true in the head, where many structures are relatively small and inaccessible. To address this problem, we are designing Web-based programs that consist of high-resolution interactive bitmap illustrations, prepared using Adobe Photoshop, and vector-based animations, prepared via Macromedia Flash. Flash action script language is used for the animations. We have used this approach to prepare a program on the pterygopalatine fossa, an important neurovascular junction in the deep face that is especially difficult to approach by dissection and to depict in static images in an atlas. The program can be viewed online at http://cds.osr.columbia.edu/anatomy/ppfossa/. A table of contents simplifies navigation through the program and a menu enables the user to identify each of the vascular and neuronal components and either to insert or to remove each from its position in the fossa. The functional anatomy of the nerves in the fossa is animated. For example, users can activate and subsequently follow action potentials as they course along axons to their targets. This high degree of interactivity helps promote learning.