DOI: 10.36347/sasjs

Pages: 253-265

One hundred two cross sections of thoracic and lumbar spines at the base and at half the length of each (63 male ,74 female) were examined with respect to x-ray density .The distribution of x-ray density was recorded using the computer densitometry .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, one comes to the conclusion that at least the spines of the 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.