Anatomical variability is a term that describes differences between anatomical structures of the animals from the same species. This variability is mainly caused by genetical effects and it may vary considerably between different populations. Rate of variability considerably differ between single organs. Therefore, the state that occurs with biggest probability is considered as a norm. It is necessary to distinguish between pathological conditions that are not considered as an anatomical variation.
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Anatomical variability Wikipedia(Text) CC BY-SA