The major three bones that form the knee joint are shin bone (tibia), the thigh bone (femur) and the knee cap (patella). These are all covered with a smooth cartilage layer.
There are two types of cartilage, articular and meniscus. Articular cartilage is a slippery substance that covers the ends of the femur, tibia, and back of the patella. It helps the knee bones glide against each other smoothly while bending or straightening the leg. The meniscus is a shock absorber that is located between the femur and tibia. It gives a cushioning effect on the joint and stabilizes it.
Bones are connected by ligaments which will keep the knee stable. There are four ligaments surrounding the knee. The two collateral, medial collateral ligament, and lateral collateral ligament are located at either side of the knee The other two cruciate, anterior cruciate and posterior cruciate are present inside the knee joint.
Muscles and tendons:
Muscles cause the knee to move back and forth whereas a tendon connects the muscle and the bone. The knee joint is affected by two primary muscle groups. Quadriceps muscles offer strength and power in knee straightening (extension), and hamstring muscles offer strength and power in knee bending (flexion).
It is a thin lining that surrounds the knee joint. The synovial cells release a slippery, viscous fluid that lubricates the cartilage and reduces friction with the movement.
This is a thin and slippery fluid-filled sac found between the bone and the soft tissue. Similar to the cartilage that reduces friction between the bones, bursae limits friction between the bones and the soft tissues (muscles and tendons). There are several bursae in the knee.