10 things you didn't know about your spine.

1. Discs don’t slip. They split, bulge, leak or break up but they don’t slip
2. The spine is made up of 24 vertebra, the sacrum and the coccyx. In between each of the vertebra there is a disc. There are 50 joints that join the spine together called facet joints.
3. In old age, the bone of the spine can be so soft that a surgeon could leave a finger impression in it.
4. If subjected to large compressive loads the vertebra will often buckle before the discs do.
5. The discs in-between each vertebra have very little blood supply; they rely on the movement of the spine to suck the surrounding nutrient rich tissue fluid in and expel waste products of metabolism out.
6. A muscle called the Latissimus Dorsi attaches to the lower five vertebra in the lower lumbar spine and travels all the up to the front of the humerus (upper arm bone).
7. In order to touch your toes your low back will only bend for the first 60°- the next 20°- 30°, depending how flexible you are, takes place because your hamstrings (leg muscles) and gluteals (butt) allow your pelvis to tilt forward.
8. An orthopaedic surgeon called Nachemson measured the pressure in the intervertebral disc of healthy subjects whilst adopting various positions. He found that the compressive pressure in your discs when standing is less than a 10th of that when you are sitting; ie in a normal man about 100kg (expressed as a weight) when standing and about 1000kg  - or 1 tonne – when sitting.
9. The intervertebral discs swell overnight with rest and there can be as much as a 2cm difference between your height first thing in the morning and at the end of the day. This also accounts for the difficulty in putting on socks for back sufferers in the morning whereas taking them off in the evening is much easier.
10. When you hear a pop from the joints in your back it is in fact small bubbles of gas created by movement of the facet joints popping and not bones cracking on each other.