The Intervertebral Disc

Disc disease, degenerated discs, slipped discs, herniated discs are common terms often related to back pain, both in your lower back and neck. Most people in the medical profession use these terms with patients, so I want to explain them to you.

What do these terms mean? How do these things happen? What can one do to help or prevent these painful events from occurring?


First some anatomy to get you on the same page: Your spinal column is made up of 24 bones called vertebrae. Each vertebra in your back has six joints; four at the back of the bone that allow and control spinal movement. These are called ‘facet’ joints. The other two joints are at the top and bottom of the vertebrae themselves. These two remaining joints in your back are weight-bearing in function. These bones protect your spinal cord.


Between each pair of the vertebrae is a intervertebral disc, except between the top two in your neck. Your discs become progressively smaller as you go up your spine. They also change shape as they go up, simply because the bones also change shape.


The most problematic discs are the lower back ones. The typical lumbar disc is almost circular in shape, but looks more like a flat car tire or mushroom head. It’s flat across the back when you look down from the top.


A disc is made up of two things: the soft central area is called the nucleus, and the tough outer cartilage margins are called the annulus. The nucleus is made of a toothpaste-like material.


The nucleus works like a ball bearing, allowing the bones to flex and extend around its shape. One of the things that builds the most pressure in your disc is when you SIT, especially in poorly supportive furniture, or when you slouch. Surprisingly, the pressure in the nucleus is three times greater in the sitting position than in the standing position. Doesn’t that speak volumes when you think of today’s lifestyle?


The annulus (outer layer) is wrapped in layers around the nucleus to contain its pressure. These layers are somewhat like the layers of an onion. These layers have to be ‘tough and non-yielding’; otherwise the soft nucleus would lose its shape and spill all over the place.


In fact this is indeed what does happen if your tough outer layer called the annulus breaks down. This incident is known variously as a ‘slipped disc, a herniated disc, a disc protrusion, a rupture, or a disc bulge’.


These terms often depend on the degree of movement, which depend on how your cartilage may break down. If you want more information, please let me know.