
The spine has 3 degrees of movement, it can rotate around its own axis, it can bend laterally and it can bend forward and back. This movement occurs across a range of smaller functional units under the influence of the muscles described in the previous page.
The degree of elbow flexion depends on the size and position of the guitar. If you're sitting the left elbow will flex more than 90˚and the right will be close to 90˚. The degree of flexion varies more when you're standing depending on how low you carry your guitar.
The two shoulders have to hold the arms in different positions and are subject to very different loads.
Apart from contributing to the position of the hand the primary function of the wrist that has relevance for us is its role in adjusting the tension in the extrinsic muscles of the hand. The wrist flexors and extensors described previously insert onto the carpal bones, parallel to these the extrinsic hand muscles cross the wrist and continue onto the fingers.
The following descriptions are meant to explain the biomechanics of the hand, not to infer a preference for one style or technique over another. Any suggestions are purely in the context of reducing the tension in the hand, if you can live with a certain amount of tension, and we all can, then whatever works for you is great. If it's not working however......