A quick look at how discs work and what they’re made of can help you understand why they’re sometimes blamed for back problems.
What’s a Disc? Each vertebra in your spine is separated from it’s neighbor by a cushion of cartilage called a disc. Discs, in fact, make up one-third of your spine’s height and serve as hydraulic shook absorbers. The outer ring of the cartilage cushion, called the annulus fibrosa, is dense and layered with crisscrossed fibers, like the covering of a radial tire. The interior cartilage, the nucleus pulposus, is soft and squishy, like thick jelly.
Healthy Discs – are like springs; they compress and release with you back’s movement. They’re flexible spacers between vertebrae, giving the bony parts and tissues of the vertebral joints room to breathe and move. At night, when your discs are free from the pull of gravity, they soak up nutrients and water from your blood, so you’re usually at your tallest in the morning.
Aging Discs – as you age, your discs lose moisture. They lose their ability to repair themselves after injury, disease or just plain wear and tear. As the disc loses moisture, it also loses height, which can put pressure on nerves and affect the way the joints of your vertebrae line up. The good news is that as the disc center loses moisture and shrinks, less pressure is put on the annulus, so that a disc injury is less likely.
Herniated Discs – a herniated disc is the most severe disc problem, often caused by a sudden injury. When the disc covering weakens before it’s center has dried out, the pressure from the center can cause the annulus to crack or rupture and the nucleus pulposa to ooze out. This protrusion can be mild, or it can cause severe pain, depending on how much of the disc center escapes and whether it presses against a nerve. Sometimes surgery is the only solution for a herniated disc.
Bulging Discs – rather than what are commonly called “slipped disc,” discs sometimes bulge out from between the vertebrae. This is especially true in the lower back. A bulging disc can irritate a nerve root or ligament, causing pain that tends to come and go. It can be brought on by bending forward.