Lateral curvature of the spine and round shoulders . odel, and child is therotation restricted to the cervical and upper dorsal spine. Rotation in the Hyperextended Position.—In hyperextended positionsrotation with moderate manual force occurs as a twisting of the whole thorax onan axis in the dorsolumbar region, the upper and middorsal regions apparentlybeing locked against rotation by hyperextension. The site of rotating movement 38 THE MOVEMENTS OF THE SPINE in this position is, therefore, in the one or two vertebrae above and the one or twovertebrae below the dorsolumbar junction. Rotation
Lateral curvature of the spine and round shoulders . odel, and child is therotation restricted to the cervical and upper dorsal spine. Rotation in the Hyperextended Position.—In hyperextended positionsrotation with moderate manual force occurs as a twisting of the whole thorax onan axis in the dorsolumbar region, the upper and middorsal regions apparentlybeing locked against rotation by hyperextension. The site of rotating movement 38 THE MOVEMENTS OF THE SPINE in this position is, therefore, in the one or two vertebrae above and the one or twovertebrae below the dorsolumbar junction. Rotation, therefore, is located high in flexed positions, lower in erect positions,and is situated lowest and is more sharply localized, in hyperextended positions. Side Bends Accompanying Rotation.—A lateral deviation of the spine accom-panies all rotations. It is situated at the site of the rotation and is convex to theright when the rotation is to the left and vice versa. In the erect position rotationcauses a marked side curve in the dorsal Fig. 28.—Rotation of the Model, Pace to the Right, Causing a Dorsal LateralCurve Convex to the Left and a Displacement of the Trunk to the Left. Reasons for Torsion.—It is obvious from these experiments that there mustbe some fundamental reason for the constant occurrence of one type of torsionfor side bendings in flexion and the occurrence of another type in extension, aswell as for the constant association of torsion with side bending. The vertebralcolumn is a flexible rod capable of bearing great weight. It is not equally flexiblein all directions, but it is, of course, capable of some movement in all planes, and,as such, should come under the control of the laws governing flexible rods ingeneral. The extent of any of the movements of the spine is, of course, greatly TORSION 39 influenced by the shape of the vertebral bodies, the curves of the spine, thecharacter of the articular processes, the resistance of the ligaments, an
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Keywords: ., bookauthorlovettrobertwrobertwi, bookcentury1900, bookdecade1910
