Within an intervertebral disc, the nucleus pulposus is located at the center.

Within an intervertebral disc, the nucleus pulposus is located at the center.

• A. At the center
• B. In the outer ring
• C. In the posterior region
• D. In the anterior region

Answer: (A)

The nucleus pulposus is the gel-like center of the intervertebral disc, positioned in the middle to form a hydrostatic cushion. The disc is organized with a central nucleus surrounded by the tough concentric layers of the annulus fibrosus. This central placement lets the nucleus distribute compressive loads evenly as the disc deforms, transferring pressure outward to the surrounding ring and to the adjacent vertebral bodies. The outer ring is the annulus fibrosus, not the nucleus, and the nucleus is not normally located in the posterior or anterior regions—that placement would place it in the surrounding fibrous tissue instead of the central gel core. (Degenerative changes can alter the nucleus’s position or composition, but in a normal adult, it sits at the center.)

The nucleus pulposus is the gel-like center of the intervertebral disc, positioned in the middle to form a hydrostatic cushion. The disc is organized with a central nucleus surrounded by the tough concentric layers of the annulus fibrosus. This central placement lets the nucleus distribute compressive loads evenly as the disc deforms, transferring pressure outward to the surrounding ring and to the adjacent vertebral bodies. The outer ring is the annulus fibrosus, not the nucleus, and the nucleus is not normally located in the posterior or anterior regions—that placement would place it in the surrounding fibrous tissue instead of the central gel core. (Degenerative changes can alter the nucleus’s position or composition, but in a normal adult, it sits at the center.)