Final answer:
The L4/L5 and L5/S1 intervertebral discs are most affected in Degenerative Disc Disease. The anulus fibrosus weakens over time, particularly with age, allowing the nucleus pulposus to protrude and leading to disc herniation. Increased spinal curvature in certain individuals can further exacerbate the risk.
Step-by-step explanation:
When considering which discs are most affected in Degenerative Disc Disease (DDD), we see that particular areas of the spine are more prone to herniation. The spinal column supports the head and upper body, and the vertebrae are cushioned by intervertebral discs, which consist of the anulus fibrosus and the nucleus pulposus. Disc herniation typically occurs when the anulus fibrosus is weakened, allowing the nucleus pulposus to protrude, especially when forward bending and lifting heavy objects. The L4/L5 and L5/S1 intervertebral discs are the most common sites for herniation due to their position and the movements and loads they endure. Similar injuries can occur at the C5/C6 or C6/C7 discs, usually from activities causing forcible hyperflexion of the neck.
As we age, the water content of the nucleus pulposus declines, making these discs thinner and less flexible, thus increasing the risk of DDD. With added curvature of the spine, such as in pregnant women or overweight individuals, the sheer forces on the discs are exacerbated, particularly at the lumbosacral disc, making it highly susceptible to degeneration and injury.