Lower Back pain


lower Back pain syndrome 4

lower Back pain  syndrome 4

functional unit in posterior portion

The posterior portion of the unit is composed of the two vertebral
,arches. two transverse processes, a central posterior spinous process
and paired articulations, inferior and superior, known as facets
The processes of the posterior arch, the transverse and the posterior
spinous, are the sites of muscular attachment. Because of the origin and
insertion of muscles from one process to another, movement of the
spine is possible. Because of the contractility and the elasticity of the
muscles, a large range of motion is possible, and the manner of attachment
and interspinous bridg;ng provides balance of the static spine
and strength for the kinetic spinal column. Maintenance of the erect
posture is in part achieved by the sustained tonus of the muscles acting
on these bony prominences. Motion and locomotion are also dependent
on these muscles playing synchronously between their points of
bony attachment


The articulations, or facets, pilot the direction of movement between
two adjacent vertebrae. By their directional planes they simultaneously
prevent or restrict movement in a direction contrary to the planes of the
articulation. They may be compared to the movement of wheels on
railroad tracks in which forward and backward movement is possible
but sideway movement is prevented.
The facets are arthrodial joints that function on a gliding basis. Lined
with synovial tissue, they are separated by synovial fluid which is
contained within an articular capsule. The plane of the facets, in their
relation to the plane of the entire spine, determines the direction in
which the two vertebrae will move. The direction, or plane, of the
facets in any segment of the spine will determine the direction of
movement permitted to that specific segment of the spine. The plane of
the facets will simultaneously determine the direction of movement
not permitted that spinal segment. Movement contrary to the direction
of the plane obviously is prevented or, at least, markedly restricted.
Because in the lumbar region the facet planes lie in the vertical
sagittal plane, they permit flexion and extension of the spine. Bending
forward and aIching backward are thus possible in the lumbar region.
Due to the vertical sagittal facet plane, Significant lateral bending and
rotation are not possible. The male portion of the facets fitting into the
female guiding portion permits movement in the direction of the
guides, but lateral, oblique, or torque movement is mechanically prevented
in the lordotic posture. In a slightly forward flexed position or
posture in which the lordosis is decreased, the facets separate, thus
allowing movement in the lumbar area, in a lateral and rotatory direction
(Fig. 9). In lumbar hyperextension the facets approximate, thus
eliminating completely any lateral or rotatory movement.
In the thoracic spine the facets are convex-concave and lie essentially
in a horizontal plane. Movement permitted by this facet plane in the
thoracic spine is lateral flexion, such as side bending and rotation about
a vertical line. A combined movement of lateral flexion and rotation
occurs here, for, in spinal column movement, no pure lateral bending is
possible without some rotation and no true rotation is possible without
some lateral flexion. Due to this facet plane, no significant flexion or
extension movement in an anterior posterior plane is possible in the
adult thoracic-spine segment (Fig. 10
In brief, the direction of the facet plane that exists between two
adjacent vertebrae in a functional unit determines the direction of
movement of those two vertebrae. As the facets of the lumbar spine are
vertical-sagittal in an anterior plane, movement of the lumbar spine
exists in an anterior-posterior flexion-extension direction. The planes
of the thoracic spine relegate to this segment all significant lateral
flexion such as side bending and rotation of the total spine. All other