What is Knee Anatomy?
The knee is one of the largest and most complex joints in the body. A hinge-type joint, the knee is responsible for bearing the body’s full weight and providing movement essential for everyday activities, such as walking, running, sitting or standing. The bones that make up the knee include:
- Lower shin bone (tibia) and the adjacent smaller bone (fibula)
- Upper thigh bone (femur)
- Kneecap (patella)
The lower end of the femur and the top end of the tibia bone create a hinge joint. The ends of these bones are covered with a coating cartilage layer, called articular cartilage. This cartilage allows the joint smooth, fluid motion. To help protect the coating cartilage layers at the ends of the femur and tibia, there are two shock absorbing meniscus cartilages that sit on top of the tibia, one on the inside of the knee (medial meniscus) and one on the outside of the knee (lateral meniscus). Together the articular cartilage and the menisci are responsible for absorbing impact.
Muscles and tendons work in conjunction to create movement across a joint. A muscle is attached to a tendon and it is the tendon portion that attaches to bone. When a muscle contracts, its tendon is pulled and the force is transmitted to bone and motion across a joint occurs. Two main muscle groups activate movement of the knee:
- The quadriceps muscles–above and in front of the knee–straightens the knee (extension)
- The hamstring muscles–behind and above the knee–bends the knee (flexion)