Aggregate Spinal Anatomy

By | March 24, 2015

Compare this normal spinal canal with...

Compare this normal spinal canal with…

... this diseased one, which shows both central spinal stenosis as well as lateral recess stenosis caused by boney overgrowth from arthritic facet joints

… this diseased one, which shows both central spinal stenosis as well as lateral recess stenosis caused by boney overgrowth from arthritic facet joints

As important as the anatomy of each individual vertebral body is, it is the relationship of the bones one to another that gives rise to most of the functional characteristics of the back and a great number of the pathological conditions that will concern us below. An intervertebral disc, which functions as a spacer and a shock absorber separates each vertebral body from the adjacent body[1]. Two important negative structures (spaces) that were hinted at above are the spinal canal[2], which houses the spinal cord and cauda equina[3], extending from the base of the skull to the end of the sacrum and the neural foramina[4], the holes through which the individual spinal nerves emerge. Each neural foramen is bounded above and below by the pedicles, anteriorly by the vertebral bodies and discs and posteriorly by the facet joints. The lumbar spine normally creates a gentle C curve, which is concave posteriorly[5].  Lateral curvature of the spine and/or rotatory displacement of one bone with respect to another is termed scoliosis[6]. Slippage of one vertebra either forward or backward with respect to the vertebra below is termed spondylolisthesis, anterolisthesis if forward and retrolisthesis if backward. This type of slippage can cause nerve root compression in two basic ways, the first by compressing the individual roots as they pass through each neural foramen[7] and the second by compressing the spinal cord or the nerve roots of the cauda equina inside the spinal canal[8]. Finally the spinal canal can be compromised by simultaneous boney overgrowth from the vertebral bodies and/or the facet joints[9].  This last form of spinal stenosis is becoming ever more prevalent especially among some of the very elderly patients we treat here at Schlesinger Pain Centers.

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[1] Individual spinal nerves can be compressed by a bulging or herniated disc most commonly at the entrance to the neural foramen.

[2] Concentric narrowing of the spinal canal is referred to as spinal stenosis.

[3] Latin for horse’s tail. In adults due to differential growth rates of bone and nervous tissue the spinal cord actually ends somewhere around L1 and all of the lower nerve roots hang downward like a horse’s tail before they exit from the appropriate neural foramen. The fact that nervous tissue in the lumbar region is made up of individual nerves rather than a solid cord changes the types of symptoms that different anatomic derangements produce.

[4] Concentric narrowing of a neural foramen is referred to as foraminal stenosis.

[5] Straightening of this curve is one of the earliest signs of spinal irritation and pain.

[6] Degenerative scoliosis is becoming a more and more important problem among the elderly. When severe scoliosis can be a cause of severe nerve root compression and even respiratory embarrassment.

[7] A form of foraminal stenosis.

[8] A form of spinal stenosis.

[9] The paradigmatic form of spinal stenosis.


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