- primary: mobility, movement
- secondary: stablitity
- fnx differs with diffferent joints
- stability: segments are kept closer together; resistance to displacement
example: upper vs. lower extemity; what joint has greater mobility UE shoulder or LE hip,knee, ankle?
hip has primary fxn of stability; 400
ROM for walking; has more potential but must be stable to support weight load; shoulder, knee, ankle have increased injuries so are less stable