Intervertebral Discs Explained: The Unsung Heroes of Your Spine

Have you ever thought about what’s at the core of your ability to bend, twist, or simply stand straight? What if we told you there’s an intricate system at work every time you make even the smallest movement with your spine? Today, we’re uncovering the fascinating world of intervertebral discs and their crucial role in maintaining the health and functionality of your spine.

Intervertebral Discs: Your Spine’s Cushiony Superheroes

Intervertebral discs are like tiny superheroes, residing between your spinal bones or vertebral bodies. They have two main components – the annulus fibrosus (AF) and the nucleus pulposus (NP).

The AF is the outer part of the disc, built like a fortress with about 20 concentric rings of sturdy collagen fibres. Imagine it as the superhero’s suit of armour, providing strength and stability. The NP, on the other hand, is the inner part and plays the role of the superhero’s superpower. It’s a gel-like substance, primarily composed of proteoglycans, which have an incredible ability to absorb and retain water, making up 70-85% of the NP’s composition.

The Dynamic Duo: AF & NP

The AF and NP join forces to deal with the compressive forces exerted on your spine. It’s like a perfectly choreographed superhero team-up. The NP, brimming with water, pushes against the AF to prevent it from buckling inwards, while the AF counters the NP’s fluid expansion, adding an extra layer of stability. It’s akin to a water-filled cushion, enabling smooth movement and protecting your spinal joints from damage.

But, these little heroes face Herculean tasks. The pressure they operate under is astoundingly high, about five times that of a typical car tyre. They use this high pressure to counteract the compressive forces that increase with activities like lifting or carrying heavy objects. In fact, they can be likened to your body’s very own ‘controlled leaky’ hydraulic dampening system!

The Discs’ Astonishing Survival Tactic

In an intriguing twist, unlike most body structures, your spinal discs lack a direct blood supply. But never fear, these resourceful superheroes have their own unique way of hydrating and nourishing themselves. They use pressure differences within the disc to expel and then reabsorb water.

During the day, as you engage in physical activities, your disc height and volume reduce by about 20%, as water is squeezed out. But come night, as you rest, water is drawn back into the NP, restoring the disc’s volume and height. This process is called ‘imbibition’. So, if you’ve ever wondered why you’re taller in the morning, you now know who to thank!

When Superheroes Face Kryptonite: Disc Problems

Despite their resilience, our intervertebral superheroes aren’t invincible. Abnormal stresses, injuries, or nutritional deficits can lead to structural damage and biological changes.

Mechanical stresses, especially in combination with forward bending, compression, side bending, and rotation, can harm the AF’s fibres. This can compromise its ability to resist the NP’s expansion, leading to mechanical failure of the disc.

Further, any disruption or damage to the proteoglycans can drastically affect the disc’s hydration and pressure. This not only ‘starves’ the disc but also causes mechanical instability of the disc and surrounding spinal ligaments.

The most common consequence is a slipped, bulging, herniated, or prolapsed disc. In such cases, the AF can no longer resist the internal pressure of the NP causing it to tear or pull away from its bony attachments. This allows the NP to push through the AF, leading to a disc that is out of alignment, a condition often associated with severe back pain and discomfort.

To Sum it Up: Celebrating Our Intervertebral Discs

Our intervertebral discs, like unsung heroes, tirelessly work behind the scenes to keep our spine functioning smoothly. They perform a delicate balancing act, constantly adjusting and readjusting to counteract the pressure and forces we put on our spines every day.

Sure, like any superhero, they have their weaknesses, and things can go wrong. But with proper care, regular exercise, and a healthy diet, we can support these disc superheroes in their important mission, enabling us to bend, twist, and enjoy life’s movements with ease.

So, the next time you bend down to tie your shoes or twist to reach for something on the top shelf, take a moment to appreciate these tiny marvels that make it all possible. Here’s to the intervertebral discs – the true superheroes of our spines!


Steve Morris is a highly experienced Osteopath with over three decades of hands-on experience. As one of the pioneering figures to introduce IDD Therapy in the UK back in 2010, Steve has not only established himself as a leading authority in the non-surgical treatment of disc conditions, but he’s also recognised as one of the country’s foremost experts in mechanical decompression through IDD Therapy.

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