Movement, stability and low back pain.

Abstract

Internal pelvic movement occurs at the SIJ. Tiny movements occur at the SIJ and these are crucial. There is a 1-2mm movement between carpals in the wrist—the accessory movements. This may not seem like much but when this small movement is lost due to say, injury, the whole of the upper limb is affected as the wrist does not function optimally therefore the elbow and shoulder do not function optimally. The left and right SIJ are different in function. Motor control is influenced by what we think. This is especially true of cramping and splinting. Form closure refers to the principle form of a joint -how does everything " fit " together? The form closure in men and women is different. In men there is more force on the SIJ as the line of gravity is further away from it. In women, this means that the line of gravity is further away form the hip. If you have decreased form closer you need increased force closure. Force closure is the extra effort required to close the joint through e.g muscle action. Deeper structures have good force closure than superficial structures. E.g cruciates are excellent as they are close to the centre of rotation and are great at self bracing. Deep muscles are therefore better at bracing. In the SIJ, nutation leads to an increase in tension in ligaments and therefor force on the joint. Making movement using a big lever increases tension in the ligament. E.f when abducting the gh joint there is automatic external rotation of the arm due to increased tension in the anterior ligaments which are 20-30% thicker than the posterior ligaments (?)