Lesson
Knee Joint Muscles-Actions
| Action (Plane of Motion) | Flexion (Sagittal) | Extension (Sagittal) | Lateral Rotation (Frontal) | Medial Rotation (Frontal) |
| Description of Motion | FLEXION is movement where posterior calf moves towards posterior thigh. Flexion from a position of full extension, as in standing posture requires the knee to first be ‘unlocked’, as the medial condyle occupies greater space than the lateral one when locked. The Poplitius medially rotates the tibia with respect to the femur to unlock the knee and permit flexion. Even in passive flexion, medial rotation of tibia and anterior translation of femur are coupled | Femur slides backwards on tibia during extension (forwards during flexion).
| Rotation of tibia relative to femur possible when knee flexed and not bearing weight. Rotational capability greatest at 90º knee flexion. |
Knee joint capable of both stability and mobility