SPINAL MECHANICS AND POSTURE WEEK 6 READING QUESTION OR TERM Centre of gravity? Centre of pressure Postural sway Stable equilibrium Unstable equilibrium Neutral equilibrium Where is postural sway measured? What are three factors that affect stability? How do you find balance and equilibrium? Does the centre of gravity change? Where is the centre of gravity in female? Where is the centre of gravity in males What happens with postural sway in the elderly? What happens if there is evidence of excessive postural sway? ANSWER OR DEFINITION Point where all the weight in the body is concentrated Point at which force vector for ground reaction force is applied. As centre of gravity moves, the centre of pressure will move. In order to disturb the object, it’s centre of gravity must be raised. The lower the centre of gravity, the more stability there is Only takes a slight push to destroy balance COG neither raised nor lowered when disturbed and the object can come to rest in any position without any change to the COG. In the sagittal and frontal plane -Height of COG -base of support -Relation of line of gravity to base of support All linear and rotary forces must be balanced. Eg; If there is downward linear force, the upward linear force causes the vector sum to be zero. Not if the shape of the object stays the same. If an objects shape or position changes, so will the centre of gravity. Transverse plane approx 55% of standing height Transverse plane appox 57% of standing height An increase in postural sway can render elderly a falls risk. It indicates that there are problems with stability.