[Morphology and mechanics of rotation of the small joint in the lumbar vertebra (author's transl)].

Using macerated and nonmacerated lumbar vertebrae and/or whole lumbar vertebral columns as well as x-rays, the attempt was made to contribute to the knowledge of the mechanics of the small joint in the lumbar section of the spinal column on the basis of the shape of the joint surfaces. The joint surfaces of the lumbar vertebral column deviate from the usual demonstration of primarily angular surfaces. Right and left joint surfaces of a locomotor segment do not lie on the same geometrical plane, i.e., there is nothing like a common right and left curvature center. As a result, conclusions can be drawn in regard to the role played by the small joint of the lumbar vertebral column under the various types of strain during movement, particularly during rotation. The relation of the small joint in rotation positions was demonstrated radiographically in isolated preparations of individual locomotor segments.