Talking about the astragalic or calcaneal function of the lower extremity with reference to specific foot functions is a hypothesis designed to provide a further approach to the biomechanical functional integration of the segmentary structures of the lower extremity. The concept of a variable load forefoot structure and the biomechanical functional division of the foot into astragalic and calcaneal foot derived from personal foot pressure and X ray research correspond to essenial static demands (hyperstatic system in the two footed stance, isostatic in the single footed stance) and also produce the mechanism of the vincular chain on which the kinetic chain depends. Biomechanical research by Torner Baduel on load transmission to the femoral lateral section of the knee intervenes in the calcaneal biomechanical phase of the foot, just as the medical section intervenes in the astragalar biomechanical phase. From a biomechanical point of view the same goes for calcaneal and astragalar knee. The concept of frontal transmission of the load to foot and knee in their various functional attitudes corresponds to specific demands for stability and is confirmed by mathematical analysis remembering that the load is expressed by the vincular reaction that subsequently (vincular chain) act along the vincular points of the system. Load oscillations on the frontal plane contribute to the interpretation of heel varus and valgus oscillations except for subastragalar calcaneal inductions at each step during walking and the frontal tranter of the load to the lower extremity intervenes in the complex of phenomena (oscillatory, torsional, pendular) that characterise the mechanism of walking. In this sense it may be meaningful to speak of astragalar and calcaneal function of the lower extremity.