Current Version - Under Revision
In addition to the subtype hierarchy represented by 116680003 |is a| relationships, SNOMED CT also represents a partonomy hierarchy using 123005000 |Part of| relationship. This creates an alternative hierarchy which can be also be used for navigation. The difference between these hierarchies is that:
The subtype hierarchy relates concepts to supertypes that represent more general concepts. Each body structure concept has an 116680003 |is a| relationship to one or more concepts that represents the whole or any part of the organ or other body part that contains it. Concepts that represent the whole or any part of an organ or body part are distinguished by their fully specified names which include the word 'structure'. These contrast with concepts that represent the entirety of an organ or body part which contain the word 'entire'.
Example: 244384009 |Entire right ventricle|(is) 123005000 |part of| 302509004 |entire heart|Note: In everyday speech the word "heart" may mean either 80891009 |heart structure|or 302509004 |entire heart|and the distinction between them is often overlooked. However, from a semantic perspective the difference is highly significant. The removal of some part of an organ does not imply the removal of the entire organ. Thus, while it is correct to state that 53085002 |Right ventricular structure| 116680003 |is a| 80891009 |heart structure|, it would be wrong to state that 244384009 |Entire right ventricle| 116680003 |is a| 302509004 |entire heart|or 53085002 |Right ventricular structure| 116680003 |is a| 302509004 |entire heart|.