Which statement best describes the nucleus pulposus?

Which statement best describes the nucleus pulposus?

• A. It is gelatinous, mostly water, avascular, and acts as a shock absorber
• B. It is fibrous with outer pain fibers
• C. It is avascular and has no nerve supply
• D. It forms the outer portion of the disc

Answer: (A)

The nucleus pulposus is the inner gel-like core of the intervertebral disc. Its high water content and gelatinous consistency allow it to deform under load and spring back, distributing compressive forces across the disc to cushion the spinal segments. It is avascular and aneural, meaning it has no blood vessels or nerve fibers, so nourishment comes by diffusion from the surrounding endplates and pain signals are typically triggered by the surrounding outer layers when injury occurs. This combination of being gelatinous, water-rich, avascular, and acting as a shock absorber best captures what the nucleus pulposus is. Other choices describe parts of the disc or only partial properties: the fibrous outer component corresponds to the annulus fibrosus; the claim about forming the outer portion is incorrect for the nucleus pulposus; and while being avascular and aneural is true, that option is incomplete without noting the gel-like, water-rich nature and shock-absorbing function.

The nucleus pulposus is the inner gel-like core of the intervertebral disc. Its high water content and gelatinous consistency allow it to deform under load and spring back, distributing compressive forces across the disc to cushion the spinal segments. It is avascular and aneural, meaning it has no blood vessels or nerve fibers, so nourishment comes by diffusion from the surrounding endplates and pain signals are typically triggered by the surrounding outer layers when injury occurs. This combination of being gelatinous, water-rich, avascular, and acting as a shock absorber best captures what the nucleus pulposus is.

Other choices describe parts of the disc or only partial properties: the fibrous outer component corresponds to the annulus fibrosus; the claim about forming the outer portion is incorrect for the nucleus pulposus; and while being avascular and aneural is true, that option is incomplete without noting the gel-like, water-rich nature and shock-absorbing function.