Common pathoanatomical conditions of the lumbar spine

(A) A superior view of a normal lumbar vertebra with cauda equina, nerve roots, intervertebral disc and ligamentum flavum.
(B) A superior view demonstrating abnormalities including a thickened ligamentum flavum, a hypertrophied facet and a herniated disc. These pathologic structures cause the canal to narrow and can impinge on the cauda equina and nerve roots.
(C) A lateral view of the lumbosacral spine demonstrating spondylolysis and spondylolisthesis. Spondylolysis is a fracture in the pars interarticularis of the vertebra. Spondylolisthesis occurs when this fracture widens and the vertebral body slides forward on the one below it. In older adults, spondylolisthesis can develop due to degenerative changes in the facet joint and intervertebral disc without an associated spondylolysis fracture.