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On the classification of the human vertebral column
Last reviewed: 04.07.2025
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The human musculoskeletal system, from the point of view of biomechanics, is a system of biokinematic chains, all of whose biolinks are united into biokinematic pairs and have connections between themselves that determine their external freedom of movement.
Laputin (1986) developed the first biomechanical classification of the musculoskeletal system, principles of biomechanical modeling of its joints and individual links. It identified 246 biokinematic pairs and 8 biokinematic chains.
The abbreviation for the biokinematic chain is made up of the Latin letters BKS (bios, kinesis, catena - biologically moving chain) and an index consisting of the Latin letter P (pars - part) of the initial letter of the Latin name of a body part or skeleton.
In the records of biokinematic pairs in the abbreviation BKS, the last letter is replaced by P. To indicate which chain the pair belongs to, the index of the corresponding chain is retained in the abbreviation (for example, BKR - pair of the vertebral column). In this case, however, it is impossible to establish which pair it is: its ordinal number should also be reported, starting from the proximal end of the vertebral column - BKR. "(or su-10). For brevity, biokinematic links (BKS) are named according to the first letters of the Latin anatomical names of the bones. If two links have the same name, for example, vertebrae in the vertebral column, then they are named from the proximal end of the chain.
The spinal column is a complex multi-link biokinematic chain (VKS - 1), formed by the atlanto-occipital joint, which unites the link of the skull and the first cervical vertebra). Thus, it is possible to determine the name of all biokinematic pairs of the VKS: C-1 - the proper pair of the skull; cv-1 - the pair formed by the biolink of the skull and the first vertebra C1; cv-2 - the pair of vertebrae C1 and C2, etc. The last 26th pair (cv-26) includes the biolinks of the sacrum and coccyx.
Since the diverse movements of the spinal column are autonomous, it is advisable to distinguish three more chains in its general biokinematic chain, determined by the presence of three mobile sections - cervical, thoracic and lumbar: cvc - biokinematic chain of the cervical section; cvt - biokinematic chain of the thoracic section; cvl - biokinematic chain of the lumbosacral-coccygeal section.
The thoracic cage consists of numerous bone formations of complex shape, possessing different degrees of mobility. Nevertheless, it can be represented as a single biokinematic chain BKSth. The thoracic vertebrae belong both to the biokinematic chain of the spinal column and to the biokinematic chain of the thoracic cage. The connections BKScv and BKSyh are realized in the area of articulation of the ribs and vertebrae. Therefore, according to the present biomechanical nomenclature, these formations are designated as connections of two relatively mobile chains, and the articulations themselves, for the purpose of a more detailed study of movements, are considered separately when observing the movements of the ribs and sternum. In essence, such a division does not represent a dismemberment of an integral region, but only facilitates its study in relatively simple parts.
The four lower free ribs can move practically independently of other biolinks of the chest; they are movably connected to the vertebrae, which sometimes allows them to be considered as independent biolinks connected only to the spinal column.
According to the biomechanical classification, there are 40 main biokinematic pairs and 4 additional ones in the biokinematic chain of the thorax. Since each rib is connected to the sternum by its thoracic part, and to the vertebrae by its vertebral part, it, in principle, forms two pairs (one with the vertebra, the other with the sternum). In view of this, instead of ordinal numbers, the indices "a" (anterior - front) and "p" (posterior - back), "s" (sinister - left), "d" (dexter - right) were added to the names of all pairs.
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