What is the predominant motion of the lumbar region? Where is the most motion occurring? Contrast the mobility and stability demands of this area

What will be an ideal response?

ANS: The predominant motion of the lumbar region is flexion-extension, with only limited lateral
flexion or rotation. What lateral flexion and rotation exist, however, are coupled opposite to the
coupling in the cervical region. That is, lateral flexion of the lumbar vertebrae is associated with
rotation of the vertebra to the opposite side. Once again, the coupling response may be dependent
upon the state of flexion-extension of the region. The motions available in the lumbar region are
largely the result of the facet joint orientation but are also influenced by the presence of the
intertransverse ligament, which limits lateral flexion and to a lesser extent, rotation.
In the flexion-extension range, flexion is more limited than extension. Flexion from neutral
(neutral = slight posterior concavity) only proceeds to the point where the spine is straight. The
lumbar spine is not normally able to reverse the lumbar curvature. The limitation in flexion is
influenced by the large anterior vertebral height and the presence of the interspinous ligaments.
The lumbar spine is generally fairly mobile (more so than the thoracic area), although at the base
of the spine, it has greater stability demands placed upon it. Its mobility results from fewer bony
restrictions (little impact of spinous processes and greater disc-to-body ratio. The contradictory
demands of this region are typified by the fact that the greatest motion in the lumbar spine occurs
at L5 to S1, although this is the lumbar interspace bearing the greatest amount of compressive
force. The lumbar area received the additional support of the thoracolumbar fascia, which is
thought to connect indirectly to and receive support from the transverse abdominis muscles.