In our context, topological information is primarily determined by the mechanical model based on the mechanical properties of the real anatomical structures. We have developed an object-oriented database and a corresponding library for its creation, editing, and access. The hierarchy of its classes is shown in Figure 6. This database provides models for bones, mechanical joints between them, ligaments, skin, and muscles. Muscles include attachments and actions lines.
Attachments are the area where muscles are bound or connected to the bones.
Together with the origin and insertion attachments classically considered by anatomy, we model also the areas on bones which constrain the mechanical action of some specific muscles. These are called the guides . Action lines model the lines along which link spindles act. Each action line is a polyline getting from an origin to an insertion attachment, possibly through any number of guides. Tendons in our case are considered as being part of the muscle.