SNOMED CT uses the Foundation Model of Anatomy (FMA) definition of body part and body part subdivision for some concepts. For example, the joint regions discussed below are classified as body part subdivisions, since that is what is intended by the diseases and procedures that use these terms in their definitions. They are not body parts because they are defined, not by a set of bones, but rather by a particular joint and its surrounding structures. However, our interpretation of the word region is based on common usage and is intended as a three-dimensional structure, not the FMA two-dimensional definition of body region. In other words, these regions are not simply surface regions (skin), but also include the three dimensional underlying structures (subcutaneous tissues, bones, muscles, tendons, fascia, vessels and etc.).
Surface regions
Many concepts contain the phrase surface region. These could be interpreted as massless (immaterial) mathematical surfaces, but a clinical terminology would have no direct use for such meanings in clinical records. They could be interpreted as having mass (not immaterial), but the depth then is arbitrary. Should it be just skin deep, or should it include deeper layers of the surface? If only skin deep, the meaning of these concepts would overlap with concepts for skin regions. If deeper, the meaning would possibly be the same as the generic structure concepts.
Inactivation
Most surface region concepts will be retired as ambiguous/possibly equivalent to their corresponding concepts that are clearly not immaterial, including x structure, entire x, and skin of X. Where the x structure codes do not currently exist, they will be created, without the surface region phrase.
Abdominal regions
The named regions of the abdomen are by tradition divided horizontally by the transpyloric plane and the interspinous plane, and vertically by the midclavicular plane. The lateral regions are therefore bounded above by a plane that is inferior to the ribs. In contrast, the flank is the lateral region of the abdomen bounded above by the ribs. Thus some parts of the hypochondriac regions, which are superior to the transpyloric plane but inferior to the ribs, would be considered also part of the flank. The hypogastric region is also sometimes called the pubic region.
Abdominal cavity, pelvic cavity
The term abdominal cavity has two meanings, one including the pelvic cavity, the other excluding it. Abdominal cavity structure includes both. Abdominal cavity proper excludes the pelvic cavity.
Organs, organ system subdivisions
The FMA definition of body organ is also used. Organs include individual bones, joints, muscles, arteries, veins, lymph vessels, nerves, and etc. Concepts that include groups of organs are frequently used in SNOMED CT. In most cases, these have been part of the subsumption hierarchy (IS A hierarchy) of the particular organ type, that is, they are kinds of organs.
For concepts that refer to the collection of organs (rather than organs in a collection), there is another concept that is a, kind of, organ system subdivision. Many such collections do not yet have corresponding organ system subdivision concepts. The default is to interpret concepts as denoting organs, rather than organ system subdivisions.
| Collections of Organs with/without Organ System Subdivisions | |
|---|---|
Organ | Organ system subdivision |
Vertebra (bone of vertebral column) | Spine (subdivision of skeletal system) |
Cervical vertebra | Cervical spine (subdivision of spine) |
Third cervical vertebra | No corresponding organ system subdivision concept |
Bone of skull | Skull (subdivision of skeletal system) |
Bone of thoracic cage | Thoracic cage (subdivision of skeletal system) |
Rib | No corresponding organ system subdivision concept |
Third rib | No corresponding organ system subdivision concept |
Right third rib | No corresponding organ system subdivision concept |
Quadriceps femoris muscle | No corresponding organ system subdivision concept |
Quadriceps femoris muscle, left | No corresponding organ system subdivision concept |
Vastus medialis muscle | No corresponding organ system subdivision concept |
Unacceptable terms
X disorder at Y level concepts from ICD-11, e.g. skin laceration of arm at wrist level (precedent are terms added from ICD-9) will not be added to the SNOMED International Release.
Cell, tissue, organ
In general, organs are made up of tissue, and tissue is made up of cells. However, a cell is not necessarily part of tissue, and tissue is not necessarily part of a named organ.
Tree structured organs
Arteries, veins, nerves, and the bronchi form tree-like structures that distribute across multiple regions. Because of their size and links with other structures, they require slightly different modeling. FMA divides tree structured organs as: organs with organ cavities and organs that are solid.
Hollow tree organs
Organ with organ cavity has a subtype, hollow tree organ. The hollow tree organs are:
- Tracheobronchial
- Biliary
- Vascular
- Arterial
- Systemic arterial
- Pulmonary arterial
- Venous
- Systemic venous (superior, inferior, and 4 cardiac trees)
- Pulmonary venous (superior and inferior left and superior and inferior right)
- Portal venous
- Lymphatic (right lymphatic duct and thoracic duct)
- Arterial
Among the solid organs, there is one category, neural, that is tree-structured (see: Nervous system; neural tree).
Breast
Male and female are unnecessary descriptions in describing the breast. Gender information should be obtained and recorded separately in the information model. New content that requests male or female breast will not be accepted so as not to duplicate gender-specific anatomical concepts.
Laterality
For information on laterality, see Anatomical Structure Naming Conventions section at Naming Convention for Digits of Hand and Foot and Laterality section at Laterality
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