Te joints move in specific ways within their plane(s) of motion. With flexion, the angle between two body parts decreases, as when you flex your elbow to move your right hand toward your right shoulder. In extension, the angle between two body parts increases, as when you extend your knee to straighten your leg. With joint abduction, a limb moves away from the midline of the body, as when you lift and move your leg to the side. In adduction, a limb moves toward the midline of the body, as when you bring your knees together. Rotation occurs in a joint when a part of the body turns in the horizontal plane, as when you rotate your femur in your hip socket to turn your leg inward or outward.


FIGURE 4.4: Foot joints are an example of gliding joints. FIGURE 4.5: Flexion and extension


FIGURE 4.6: Abduction and adduction ABDUCTION


ADDUCTION


FLEXION EXTENSION


ADDUCTION Hip Joint


Te hip is a ball-and-socket joint consisting of the side (socket) of the pelvis and the head (ball) of the femur. Te femur moves at the hip joint in all three planes, similar to a computer joystick. Technically, the femur rotates, abducts, adducts, flexes, and extends in the hip joint.


Te hip’s range of motion plays a vital role in skiing. It allows the legs to rotate and turn the skis (rotational-control skill). It allows the legs to flex and extend to manage pressure (pressure-control skill). It also allows the legs to move sideways, whether by lifting a leg outward to the side or by moving the pelvis sideways (edge-control skill). Rotation, abduction, and adduction of the leg at the hip, combined with knee flexion, allows the knee to “tip” sideways into a turn (rotational-, edge-, and pressure-control skills).


62 PSIA ALPINE TECHNICAL MANUAL TheSnowPros.org


ABDUCTION


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