In balance

When I think about my head balancing on top of my spine it reminds me a little of these zen rocks - a beautiful arrangement.

The bones of the human skeleton are stacked up high, rather like these rocks, but of course we can move about, on relatively tiny little feet, in a continuous, incredible relationship with gravity.

The key to upright balance is the interaction of gravity with the human head - which is astonishingly heavy - approximately 11lb or 5k. I have a bag of sand which people can hold in their hands to demonstrate this weight and it never ceases to amaze.

The head balances on top of the neck - two tiny, bony rockers called the occipital condyles rest in corresponding dips in the atlas vertebra. If you feel these parts on a model skeleton they are hardly bigger than your finger tips.

Two thirds of the weight of the head is IN FRONT of the neck, so if it wasn't for our muscles and tendons and so forth, there's no way it would stay put like the zen rocks.

The weight of the head constantly pulling forwards exerts a force on the erector spinae muscles, pulling the spine upwards. This creates an antagonistic pull - gravity literally pulling our two ends apart - our whole weight into the earth through our feet and simultaneously, our whole weight pulling upwards thanks to the heavy head.

The human musculoskeletal system - a perfect design. Alexander lessons simply improve on what's already there.