Which disc component acts as a shock absorber and permits a very limited range of motion between adjacent vertebrae?

• A. Annulus fibrosis
• B. Nucleus pulposus
• C. Endplate
• D. Vertebral body

Answer: (B)

The nucleus pulposus is the gel-like center of the intervertebral disc. Its high water content and proteoglycan-rich matrix let it act as a hydraulic cushion, distributing compressive loads across the disc and toward the endplates. This cushioning reduces peak stresses on the vertebral bodies and allows only a small amount of motion between adjacent vertebrae, contributing to stability while permitting limited bending. The surrounding annulus fibrosus provides containment and resists tension and torsion, the endplates transfer load to the vertebral bodies, and the vertebral body is bone, not a disc component.