The knee is the body’s largest and one of its most complex joints. It functions like a hinge, linking the thigh bone (femur) to the shin bone (tibia). To fully understand the knee, it’s helpful to know its structure. Articular cartilage covers the ends of the bones and the underside of the kneecap, allowing smooth movement. Ligaments, which are strong, rope-like bands, hold the joint together and provide stability. There are four key ligaments: two outside the joint—the medial and lateral collateral ligaments—and two inside—the anterior and posterior cruciate ligaments. The meniscus, a horseshoe-shaped cartilage pad, acts as a cushion or shock absorber between the bones. Surrounding muscles give strength, power, and additional stability, while tendons, the specialized ends of muscles, connect them to bones.