Joint Stability and Classification

planar(gliding) joints

multiaxial movement; no change in angle; ex. intercarpals

Hinge joints

permits angular motion; ex elbow; knee

Pivot Joints

permits uniaxial rotation; ex. atlantoaxial(shake head no joint)

Ellipsoidal (condyloid) joints

permits biaxial angular motion; looks like a joystick; ex. radiocarpal(wrist joint)

Saddle joints

permits biaxial angular motion; looks like a saddle; ex. carpometacarpo of thumb

Ball and socket joints

permits multiaxial motion; ex. shoulder

Factors contributing to joint stability include:

collagen fibers, bone shape, obstruction of movement, tension in tendons

Sprains

tears in ligaments

Strains

tears in muscle or tendons

fibrosis

hardening of articular surfaces, causing friction and inflammation(arthritis)