SGBP Final 4

Disc in extreme extension

In backward bending (extension) the squeezed nucleus pulposus moves
away from the spinal cord hence there is no risk of compression of the
spinal cord or its nerve roots.

At first glance it may appear that the intervertebral disc is compressed equally on
forward or backward bending. However, it must be remembered that we can bend
forward till we almost double up while backward bending is restricted to only 20° by the
intervertebral joints. Thus, the pressure on the disc is far more in forward
bending and can result in disc bulging and herniation especially if the outer capsule –
the annulus fibrosus – is weak or fragmenting in parts. Secondly when there is
herniation at the back of the disc due to forward bending, the nucleus pulposus pushes
backwards where the spinal cord and intervertebral foramina with spinal nerves are
located leading to compression.