Authors and contributors:

• Chris Mungall (author)
• Wasila Dahdul (author)
• Melissa Haendel (author)

Date: 2013

Document Type: ontology_design_pattern

Joints or articulations are structures that connect the elements of the skeletal system, or more generally, any articulated hardended body parts.

We include a grouping class articulation, which is applicable to the joints of a variety of metazoans, including insects, and skeletal joint, which is specific to the skeletal elements of vertabrates.

• articulation -- any hardened body parts
  • skeletal joint -- parts of the skeletal system

A skeletal joint is the disjoint union of synovial and non-synovial forms - i.e. the following subhierarchy is jointly exhaustive and pairwise disjoint

• skeletal joint
  • synovial joint
  • nonsynovial joint

We do not require that every skeletal joint is asserted under one of these two subclasses.

We use the connects relationship type to link between a joint and two (or more) skeletal elements (or other hardened body parts).

Note that we do not require a relationship to be stated between a body part and a joint - this is allowed, but care should be taken, as connectivity varies across taxa. For example, the quadrate-articular joint always connects a quadrate and an articular by definition. However, an articular is not always connected to a quadrate.

The template that should be followed is:

  Class: 'X-Y joint'
  EquivalentTo: `skeletal joint` AND
   connects some X AND
   connects some Y

(the genus term can be relaxed for non-vertebrates)

We can use the connects relationships to infer a connection between skeletal elements, but only in taxa for which that joint exists.