What Structures of the Spine Are Involved?
The spine is a column of 26 bones that extend in a line from the base of the skull to the pelvis (see fig. 1). Twenty-four of the bones are called vertebrae. The bones of the spine include 7 cervical vertebrae in the neck; 12 thoracic vertebrae at the back wall of the chest; 5 lumbar vertebrae at the inward curve (small) of the lower back; the sacrum, composed of 5 fused vertebrae between the hip bones; and the coccyx, composed of 3 to 5 fused bones at the lower tip of the vertebral column. The vertebrae link to each other and are cushioned by shock-absorbing disks that lie between them. The vertebral column provides the main support for the upper body, allowing humans to stand upright or bend and twist, and it protects the spinal cord from injury. Following are structures of the spine most involved in spinal stenosis. (See figs. 1, 2 and 3, and fig. 7.) Intervertebral diskspads of cartilage filled with a gel-like substance which lie between vertebrae and act as shock absorbers. Facet
