Which movement characterizes the unilateral action of the quadratus lumborum?

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Multiple Choice

Which movement characterizes the unilateral action of the quadratus lumborum?

Unilateral contraction of the quadratus lumborum produces lateral flexion of the trunk toward the same side. This muscle spans from the iliac crest to the 12th rib and the lumbar transverse processes; when it tightens on one side, it pulls the lower rib and the lumbar region toward that side, bending the spine laterally. It doesn’t primarily rotate the trunk to the opposite side, and flexion or extension of the trunk are mainly produced by other muscles (flexors like the abdominal muscles for forward bend, and the back extensors for spine extension when contracting bilaterally). So the movement best described by the unilateral action is lateral flexion of the trunk to the same side.

Unilateral contraction of the quadratus lumborum produces lateral flexion of the trunk toward the same side. This muscle spans from the iliac crest to the 12th rib and the lumbar transverse processes; when it tightens on one side, it pulls the lower rib and the lumbar region toward that side, bending the spine laterally. It doesn’t primarily rotate the trunk to the opposite side, and flexion or extension of the trunk are mainly produced by other muscles (flexors like the abdominal muscles for forward bend, and the back extensors for spine extension when contracting bilaterally). So the movement best described by the unilateral action is lateral flexion of the trunk to the same side.

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