<P> The first two laws were developed by Dr. Fryette in 1918, and the third was developed by C.R. Nelson, D.O in 1948 . </P> <Ol> <Li> Principle I: When the spine is in neutral, sidebending to one side will be accompanied by horizontal rotation to the opposite side . This law is observed in type I somatic dysfunction, where more than one vertebra is out of alignment and cannot be returned to neutral by flexion or extension of the vertebrae . The involved group of vertebrae demonstrates a coupled relationship between sidebending and rotation . When the spine is neutral, side bending forces are applied to a group of typical vertebrae and the entire group will rotate toward the opposite side: the side of produced convexity Extreme type I dysfunction is similar to scoliosis . </Li> <Li> Principle II: When the spine is in a flexed or extended position (non-neutral), sidebending to one side will be accompanied by rotation to the same side . This law is observed in type II somatic dysfunction, where only one vertbral segment is restricted in motion and becomes much worse on flexion or extension . There will be rotation and sidebending in the same direction when this dysfunction is present . </Li> <Li> Principle III: When motion is introduced in one plane it will modify (reduce) motion in the other two planes . The third principle sums up the other two laws by stating dysfunction in one plane will negatively affect all other planes of motion . </Li> </Ol> <Li> Principle I: When the spine is in neutral, sidebending to one side will be accompanied by horizontal rotation to the opposite side . This law is observed in type I somatic dysfunction, where more than one vertebra is out of alignment and cannot be returned to neutral by flexion or extension of the vertebrae . The involved group of vertebrae demonstrates a coupled relationship between sidebending and rotation . When the spine is neutral, side bending forces are applied to a group of typical vertebrae and the entire group will rotate toward the opposite side: the side of produced convexity Extreme type I dysfunction is similar to scoliosis . </Li> <Li> Principle II: When the spine is in a flexed or extended position (non-neutral), sidebending to one side will be accompanied by rotation to the same side . This law is observed in type II somatic dysfunction, where only one vertbral segment is restricted in motion and becomes much worse on flexion or extension . There will be rotation and sidebending in the same direction when this dysfunction is present . </Li>

Side bending and rotation in the lumbar spine