AN50.1-4 | Vertebral column — Glossary

Gelatinous centre of the intervertebral disc; embryological remnant of the notochord; acts as a hydraulic shock absorber

Concentric rings of fibrocartilage forming the outer part of the intervertebral disc; posterior part is thinner, predisposing to posterolateral herniation

Herniation of the nucleus pulposus through a tear in the annulus fibrosus, typically posterolateral, compressing adjacent nerve roots

Ligament on the posterior surface of vertebral bodies within the vertebral canal; narrow laterally, allowing posterolateral disc herniation

Strong broad ligament on the anterior surface of vertebral bodies; prevents hyperextension of the vertebral column

Elastic ligament connecting adjacent laminae; yellow colour from elastin; may hypertrophy causing spinal canal stenosis

Facet joint — synovial plane joint between articular processes of adjacent vertebrae; orientation determines regional movement

Lateral curvature of the vertebral column with vertebral rotation; most commonly idiopathic in adolescent girls

Exaggerated posterior convexity of the thoracic spine; Pott's disease (TB) is the most common cause in India

Exaggerated anterior convexity of the lumbar spine; commonly seen in pregnancy and obesity

Forward slippage of one vertebra over the one below; most commonly L4 over L5 due to pars interarticularis defect

Defect (fracture) in the pars interarticularis of the vertebral arch; predisposes to spondylolisthesis

Bundle of lumbar and sacral nerve roots below the conus medullaris resembling a horse's tail; freely floating in CSF

Tapered terminal end of the spinal cord at L1-L2 in adults and L2-L3 in neonates

Procedure to sample CSF by inserting a needle into the subarachnoid space at L3-L4 or L4-L5, safely below the conus medullaris

Supracristal line connecting the highest points of the iliac crests, crossing the vertebral column at L4 spinous process; used to locate the L3-L4 interspace

Strong joint between the sacrum and ilium; partly synovial, partly syndesmosis; transmits body weight to the lower limbs

Secondary cartilaginous joint between the two pubic bones; slight movement allowed during pregnancy by relaxin

Failure of the vertebral arch to fuse posteriorly; ranges from occulta (asymptomatic) to myelomeningocele (cord herniation with paralysis)

Tuberculosis of the spine; the most common cause of paraplegia in young Indians; causes vertebral body destruction and kyphotic (gibbus) deformity

Opening between adjacent pedicles through which the spinal nerve, radicular vessels, and meningeal branches pass

Lasegue's sign — passive raising of the extended leg reproduces sciatic pain in disc prolapse; positive at less than 60 degrees indicates nerve root compression