The knee is the largest joint in the body and one of the most complicated. It acts like a hinge joint connecting your thigh bone (femur) to your shin bone (tibia). To understand the knee, it is important to understand its anatomy. Lining articular cartilage covers the ends of the bones and underside of the kneecap, and helps the joint glide smoothly. Ligaments are rope like structures that hold the joint together and provide stability. There are four main ligaments in your knee, two outside the joint (medial and lateral collateral ligaments), and two inside the joint (anterior and posterior cruciate ligaments). The meniscus is a horseshoe shaped pad of cartilage that functions as a cushion or shock absorber between the bones. The muscles around the knee provide strength and power, and also help stabilize the joint. Tendons are the specialized ends of the muscles that connect them to bones.