In human anatomy, the knee is the lower extremity joint connecting the femur and the tibia. Since in humans the knee supports nearly the entire weight of the body, it is vulnerable both to acute injury and to the development of osteoarthritis.
Function Of The Knee
The knee functions as a living, self-maintaining, biologic transmission, the purpose of which is to accept and transfer biomechanical loads between the femur, tibia, patella, and fibula. In this analogy the ligaments represent non-rigid adaptable sensate linkages within the biologic transmission. The articular cartilages act as bearing surfaces, and the menisci as mobile bearings. The muscles function as living cellular engines that in concentric contraction provide motive forces across the joint, and in eccentric contraction act as brakes and dampening systems, absorbing loads.
The knee is a complex, compound, condyloid variety of a synovial joint which hovers. It actually comprises two separate joints.
The femoro-patellar joint consists of the patella, or "kneecap", a so-called sesamoid bone which sits within the tendon of the anterior thigh muscle (m. quadriceps femoris), and the patellar groove on the front of the femur through which it slides.
The femoro-tibial joint links the femur, or thigh bone, with the tibia, the main bone of the (lower) leg. The joint is bathed in a viscous (synovial) fluid which is contained inside the "synovial" membrane, or joint capsule.
The recess behind the knee is called the popliteal fossa.