Thoracolumbar Spine Anatomy and Pathology - Midlumbar Spinal Canal through L4-L5

Closeup view of the midlumbar spinal canal in a severely degenerated and stenotic specimen from an elderly male adult who had a history of prolonged low back pain without radicular symptoms. The intervertebral disc is completely resorbed. Behind the vertebra above and below the ventral internal veins are engorged. At the posterior aspect of the disc a beak–shaped spondylosis ridge projects into the spinal canal. The bone of this projecting osteophyte has a light color (sclerotic), note that the outermost annulus fibrosus (darker color) is still present. Posteriorly the loss of segmental height entails an approximation of the spinous processes and laminae ("kissing spines"). The articulating surfaces of this neoarthrosis are covered with cartilage and are also bounded by bizarre osteophytes. Note also the effusion in the neoarthrosis between the laminae. The interlaminar ligamentum flavum is probably only thickened by retraction due to the redundance and "mushrooms" into the spinal canal and compresses the traversing intrathecal root against the hard spondylophytic beak. It is obvious that the root still is inside the thecal sac, therefore the compression is more medial than only in the foramen and lateral recess.

©2000 Wolfgang Rauschning, M.D., Ph.D.
Professor of Clinical Anatomy
Academic University Hospital
Department of Orthopaedic Surgery
Uppsala, Sweden
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