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Abstract:
The erect posture of man is not due to a static rigidity of the vertebral column, but to an extremely dynamic function of the whole locomotor system of the trunk, especially the multiple biomechanical and functional possibilities of the vertebral column. Vertebrae intervertebral disks, ligaments (vertebral motor segment; Junghanns, 1966), back muscles, and the adjacent organ systems have to be considered as a functional unit. The erect posture is one of the most decisive acquisitions in the phylogenetic development of man. The vertebral column starts its adaption to this condition already during the last embryonal months by rearranging the small lumbar vertebral joints, beginning with the transition between thoracic and lumbar spine. In many cases this adaption is not finished and remains incomplete in the region of transition between lumbar and sacral spine. Only the erect posture has released the hands and made possible the use of tools and the evolutionary progress of the brain which is closely connected to this ability. This most recent phylogenetic adaption of a particularly loaded region has produced a weak point in the construction of our bodies. This is the price we have to pay for our erect posture which has been essential to the development of the specific human way of life, i.e. the formation of language and culture.