The Distribution of Bone Mass in the Cross Section of Human Vertebra

One hundred two cross sections of thoracic and lumbar spines at the base and at half the length of each (76 years old male, 63 years old male, 74 years old female) were examined with respect to x-ray density. The distribution of x-ray density was recorded using the computer densitometry. The density distribution was displayed in 10 colors and density level, as a graphical two-dimensional image. An irregular distribution of density on the sections plane was found. The higher density levels lied at the cranial and caudal edge. Between zones of less density. This distribution complies with the stress diagram which would beg to bending stress in sagittal level. By evaluating the biomechanical literature (Pawels 1948, 1950,1954,1968 and Kummar 1960, 1962, 1972, 1987), one comes to the conclusion that at least the spines of the human thoracic and lumbar are adjusted at a bending stress and in this manner were also stressed in life time. Functional adaptation of the bone on its mechanical stress is reached by several factors of bone materials at the same time.