We have things that are connected together, and things which border each other. The orientation of the objects or spaces needs to be represented. We will use an orientation operator, with four connections, two of which represent directions – here are some of the directional adjectives (some are prepositions, so they are enclosed in lists to prevent acquiring the wrong part of speech):

DirectionalAdjectives.png (81731 bytes)

We will use "contiguous" to mean that regions or objects abut.

Will the orientation always be fixed – what if positions reverse, or do we then use a relation? Should we have a logical control anyway?

For a simple case of two components of a duct which are adjacent to each other, we end up with

SingleORIENT1.png (42578 bytes)

The logical control means only that it should be used when it is true, and in a simple case it is a true existential constant.
The downstream end of one part of the small intestine is contiguous with the upstream part of the next.

For the esophagointestinal tract

orient1.png (105538 bytes)

Medical Design Notes