In order to ensure the curriculum ontology’s flexibility and extensibility, we are linking the anatomical concepts used in our ontology to the concept identifiers in the UMLS Knowledge Sources [12, 13]; in particular, we are linking our ontology to the University of Washington Digital Anatomist (UWDA) ontology. The UWDA has contributed 15000 anatomical concepts, primarily for the thoracic region, to the 1998 version UMLS metathesaurus [UWDA97].  These terms were gathered as part of a larger project to developed a principled ontology which can accommodate systemic and regional (or topographical) views of anatomy [8, 14, 15]. The top level of the UWDA ontology is ‘physical anatomical structure’, which is also the top level for our ontology; the concept space for physical anatomical structure is shown in Figure 4.

     Because ‘physical anatomical structure’ is an abstract concept, note that no image can be displayed.

     At an intermediate level, we have added to the ontology a system for  specifying regions using features, as shown in Figure 5.

     This ontology fragment shows that bones are in an is-a relation to  anatomical structure and that bones of specific anatomical regions, such as the bones of the pelvis, are in an is-a relation to the general category of bones. Figure6.

     This makes it possible for a user who is interested, for example, in bones of the different regions, to navigate among the regions.

     We have plans for expanding the number of concepts and  relations and for the enhancement of the ontology with additional features that will provide a variety of ways for users to navigate among related anatomical entities.  As the prototype is expanded and extended, we will evaluate its utility as a self-study application and as a navigational system.