From the front of the knee, the white shiny joint cartilage is exposed as the knee is bent. The two rounded ends of the femur bone are called the 'condyles' or 'femoral condyles'. The notch between the condyles is called the 'notch' or 'intercondylar notch'.
As the knee is straightened, the rounded ends of the thighbone (condyles) roll over and the important joint cartilage is tucked under and protected.
You can see that the kneecap (patella) is actually within the substance of a tendon - the tendon of the quadriceps muscles (the lap muscles). You can see the cruciate ligaments within the joint and the collateral ligaments on the outside.
The menisci - shock absorbers that fill the space and allow smooth movement of the joint - are sandwiched between femur and tibia.