Glossary items beginning with S (15).
Sacral Spine - (Sacrum) - The curved triangular bone at the base of the spine, consisting of five fused segments of the lower spine that have four foramen on each side. The sacrum articulates (connects) with the last lumbar vertebra and laterally with the pelvic bones.
Sacroiliac Joint - The joint between the ilium and sacrum one each side of the pelvis which has a small amount of motion. It may be a source of low back pain. The ligamentous attachments may become injured as well.
Sacroilitis - Inflammation within the sacroiliac joint. This may be an associated symptom of ankylosing spondylitis.
Sciatica - A lay term indicating pain along the course of a sciatic nerve, especially noted in the back of the thigh and below the knee.
Scoliometer - A proprietary name for an inclinometer used in measuring trunk rotation.
Scoliosis - Lateral deviation of the normal vertical line of the spine which, when measured by x-ray, is greater than ten degrees. Scoliosis consists of a lateral curvature of the spine with rotation of the vertebrae within the curve. Rotation of the vertebrae also occurs which produces the rib cage and flank muscle asymmetry.
Spinal Canal - The long canal between the vertebral bodies anteriorly and the lamina and spinous processes posteriorly through which the spinal cord passes. The spinal cord and nerve roots extend to the level of the second lumbar segment in adults. Below this level are numerous nerve roots from the spinal cord that resemble a horse's tail and is referred to as such (cauda equina). The thick outer covering of the spinal cord is called the dura.
Spinal Fusion - A surgical procedure of stabilizing (permanently join to prevent motion) two or more vertebra by bone grafting. Can be done from the front (anterior), back (posterior), or as a staged procedure (first anterior and then posterior), usually with instrumentation.
Spinal Instrumentation - Metal implants fixed to the spine to improve spinal deformity while the fusion solidifies (becomes solid bone). This includes a wide variety of rods, hooks, wires, and screws used in various combinations.
Spinal Stenosis - Narrowing or reduction in the diameter of the spinal canal which surrounds the spinal cord, spinal roots and spinal sac (dura). This may secondary to a disc herniation, bone fracture, arthritic overgrowth of bone and soft tissue, or occasionally may have developed before birth.
Spinous Process - The portion of the vertebrae that protrudes posteriorly from the spinal column. The spinous processes create the "bumps" felt on the midline of the back.
Spondylitis - An inflammatory disease of the spine.
Spondylolisthesis - An anterior displacement (slipping) of a vertebra on the adjacent lower vertebra. There are several causes for this. There can be varying degrees of displacement so the vertebra and the spine above that vertebra are displaced forward in relationship to the vertebrae below. It is frequently due to a developmental defect or the result of a fracture.
Spondylolysis - (also referred to as a stress fracture or a pars fracture) - Fracture of a posterior portion of the vertebra with a defect in the neural arch between the superior and inferior facets of vertebrae without separation at the defect and therefore no displacement of the vertebrae. It may be unilateral or bilateral and is sometimes due to a developmental defect but may be secondary to an traumatic fracture.
Structural Curve - A segment of the spine that has fixed (nonflexible) lateral curvature.