My Spine - Lumbar
Thecal sac – This is the name given for the elongated membraneous tube that
extends from the brain to the end of the spine in which the spinal cord and
nerve roots run. It is made up of – and is continuous with – the membrane that
covers the brain.
Flattening of the thecal sac – This is a description of the situation that occurs
when a herniated (slipped or prolapsed) disc has extended so far into the
spinal canal that it is pushing on the thecal sac.
erve root – This is the nerve root that leaves the thecal sac and exit the
spine through the intervertebral foramen. Most of the exiting nerve roots can
be seen side-on in the axial planes as well as the coronal planes and are seen
end-on in the sagittal plane.
Foraminal stenosis – This is a narrowing of the foramen and the exiting
nerve root can become compressed in the foramen by either a disc herniation
or a hypertrophied facet joint or a combination of both.
Spondylolisthesis – This is the term that describes a slip of one vertebra on
the vertebra directly below and is secondary to a weakness in the bone that
supports the facet joints that keep the spine stable.
Spondylolysis – This is frequently the cause for spondylolisthesis and is the
process where the bone supporting the facet joints is weak and fractures.
Spondylosis – This is spinal degeneration and is characterised by bone spurs
(osteophytes) that develop on the vertebral bodies and are usually asympto-
matic, except if they compress nerves.
Synovial cyst – The joint space of the facet joints are lined with a membrane
– the synovial membrane – which allows for free and easy movement of the
joint. Sometimes, as the joints become damaged, this synovial membrane can
bulge out and form a cyst.
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