Which disc portion contains outer pain fibers?

Which disc portion contains outer pain fibers?

• A. Annulus Fibrosis
• B. Nucleus Pulposus
• C. Endplate
• D. Vertebral Body

Answer: (A)

Pain from a healthy disc mainly comes from the outer portion of the disc because that region, the annulus fibrosus, contains sensory nerve endings. The nucleus pulposus in the center lacks nerves and blood vessels, so it isn’t a direct source of discogenic pain under normal conditions. When the disc degenerates or a disc herniation irritates adjacent structures, pain often arises from the outer layers of the annulus fibrosus where nociceptors are concentrated. The endplate is just the boundary between the disc and vertebral body, and the vertebral body’s pain sources lie in the bone and periosteum, not within the disc itself. Therefore, the portion containing outer pain fibers is the annulus fibrosus.

Pain from a healthy disc mainly comes from the outer portion of the disc because that region, the annulus fibrosus, contains sensory nerve endings. The nucleus pulposus in the center lacks nerves and blood vessels, so it isn’t a direct source of discogenic pain under normal conditions. When the disc degenerates or a disc herniation irritates adjacent structures, pain often arises from the outer layers of the annulus fibrosus where nociceptors are concentrated. The endplate is just the boundary between the disc and vertebral body, and the vertebral body’s pain sources lie in the bone and periosteum, not within the disc itself. Therefore, the portion containing outer pain fibers is the annulus fibrosus.