The purpose of this thesis is to describe the development of children's locomotor system. Growth and development are permanent dynamic processes that last from the conception to the full maturity following the order which is roughly the same for everybody. Children of the same age show huge difference in their physical and mental maturity, which means that the developmental pace of children of the same age group varies. All the children undergo stages of ossification, musculisation and myelination. Ossification is the process of development of bone tissue, which begins in the prenatal period when cartilage gradually transforms into the bone tissue and ends no earlier than adolescent period. The bones of preschool child have a lot of cartilage, which is the reason why they change the shape easily and are prone to deformities. Musculisation is the process of development of muscle fibres happening as the mass and structure of muscles increase. The development of motor skills is directly caused by the process of myelination, i.e. the process of nerve tissue maturation. The process of ossification, musculisation and myelination are directly responsible for the locomotion of children and the manifestation of motor and functional abilities.