Final answer:
The medial and lateral menisci, along with the tibial and fibular collateral ligaments, and cruciate ligaments, absorb shock and stabilize the knee joint by preventing side to side movement of the femur on top of the tibia.
Step-by-step explanation:
The structures of the knee joint that absorb shock and prevent the femur from moving side to side on the tibia are primarily the medial meniscus and lateral meniscus.
These C-shaped fibrocartilage structures provide padding between the femur and tibia and help to fill gaps between the rounded femoral condyles and the flattened tibial condyles.
Supporting them, the tibial collateral ligament and fibular collateral ligament on the medial and lateral sides, respectively, along with the anterior and posterior cruciate ligaments within the knee joint, help to stabilize the knee and prevent hyperextension or excessive rotation.