[Biomechanics of the bones and skeleton. III. Microstructure].

The authors analyzed micro- and ultrastructure of Haversian system--osteon--from the aspect of mechanics--biomechanics. The evaluation takes into account biological factors and instead of mathematical formulae and calculations prefer a comparison with technical constructions, particularly for emphasizing differences or similarities. The analysis of osteon revealed that it consists of fibres, net and tubes. The orientation of tube-like lamellae is in the direction of compressive strain, whereas the resultant course of torison and bending stress may be well observed in the direction of collagen fibres. A slight assymetry of osteons suggests that they are stressed by pressure in a slightly excentric direction. In the course of stress lengthwise there is the development of extension of the Haversian canal supporting the blood flow in the capillary. In the course of stress in the osteon lengthwise there are developing pressure, torsion and bending strains. Liquid phase can, together with collagen, absorb considerable portion of kinetic energy, thereby decreasing the strain of external strengths to act on the fragile mineralized component. Without the viscous and collagen elements the mineralized component would not be able to resist the dynamic forces which develop during the stresses in the bone tissue. Identification of mechanic phenomena of osteon provides information on structural principle of the whole bones. The authors applied in their study the knowledge from the discovery of USSR No. 181 and a discovery of CSSR No. 43.