Glossary

Sacrum - A part of the spine that is also part of the pelvis. It articulates with the ilia at the sacroiliac joints and articulates with the lumbar spine at the lumbosacral joint. The sacrum consists of five fused vertebrae that have no intervertebral discs.

Sagittal - Refers to a lengthwise cut that divides the body into right and left portions.

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.

Scoliosis - Lateral (sideways) curvature of the spine.

Sepsis - A state of infection of tissue due to disease-producing bacteria or toxins.

Sequestrated disc - An extruded disc in which a portion of the disc tissue is displaced beyond the outer anulus and maintains no connection by disc tissue with the disc of origin.

Sequestrum - Disc tissue that has become displaced from the disc space of origin and lacks any continuity with disc material within the disc space of origin. Syn: disc fragment. See: sequestrated disc

Skeleton - The rigid framework of bones that gives form to the body, protects and supports the soft organs and tissues, and provides attachments for muscles.

Spinal Canal - The bony channel that is formed by the intravertebral foramen of the vertebrae and in which contains the spinal cord and nerve roots.

Spinal Column - See Spine.

Spinal Cord - The longitudinal cord of nerve tissue that is enclosed in the spinal canal. It serves not only as a pathway for nervous impulses to and from the brain, but as a center for carrying out and coordinating many reflex actions independently of the brain.

Spinal Disc - See Disc (Intervertebral).

Spinal Fusion - A surgical procedure to permanently join bone by interconnecting two or more vertebrae in order to prevent motion (see Arthrodesis).

Spinal Stenosis - Reduction in the diameter of the spinal canal due to new bone formation which may result in pressure on the spinal cord or nerve roots.

Spine - The flexible bone column extending from the base of the skull to the tailbone. It is made up of 33 bones, known as vertebrae. The first 24 vertebrae are separated by discs known as intervertebral discs, and bound together by ligaments and muscles. Five vertebrae are fused together to form the sacrum and 4 vertebrae are fused together to form the coccyx. The spine is also referred to as the vertebral column, spinal column, or backbone.

Spondylitis - Inflammation of vertebrae.

Spondylitis - Inflammatory disease of the spine, other than degenerative disease. Note: Spondylitis usually refers to non-infectious inflammatory spondyloarthropathies.

Spondylolisthesis - A defect in the construct of bone between the superior and inferior facets with varying degrees of displacement so the vertebra with the defect and the spine above that vertebra are displaced forward in relationship to the vertebrae below. It is usually due to a developmental defect or the result of a fracture.

Spondylosis - Spondylosis deformans, for which spondylosis is a shortened form.

Spondylosis deformans - Degenerative process of the spine involving essentially the anulus fibrosus and characterized by anterior and lateral marginal osteophytes arising from the vertebral body apophyses, while the intervertebral disc height is normal or only slightly decreased. See: degeneration, spondylosis.

Spondylosis - 1. Spondylosis deformans, for which spondylosis is a shortened form. 2. (Non-Standard) Any degenerative changes of the spine that include osteophytic enlargement of apophyseal bone.

Stainless Steel - Iron-based metal containing chromium that is highly resistant to stain, rust, and corrosion. Certain grades of stainless steel are commonly used to make surgical implants and instruments.

Sterile - Free from living organisms.

Sterilization - The method used to render a material free from living organisms. Usual methods include steam under pressure, gas, and ionizing radiation.

Sub-anular herniation - Disc herniation in which a displaced portion is contained by anulus.

Sub-articular zone - The zone, within the vertebral canal, sagittally between the plane of the medial edges of the pedicles and the plane of the medial edges of the facets, and coronally between the planes of the posterior surfaces of the vertebral bodies and the under anterior surfaces of the superior facets.

Sub-ligamentous - Beneath the posterior longitudinal ligament.

Sub-membranous - Enclosed within peridural membrane.

Superior - Situated above or directed upward toward the head of an individual.

Supra-pedicular level - The level within the vertebral canal between axial planes of the superior end-plate of the vertebra caudad to the disc space in question and the superior margin of the pedicle of that vertebra. Syn: inferior vertebral notch.

Syndesmophytes - Thin and vertically oriented bony outgrowths extending from one vertebral body to the next and representing ossification within the outer portion of the anulus fibrosus.