Anatomy, Bony Pelvis and Lower Limb, Nerves

The knee is the largest joint in the body. It is a compound synovial joint that consists of the tibiofemoral joint and the patellofemoral joint. It primarily serves as a hinge joint which allows flexion and extension as well as various other movements. It joins the lower leg and thigh bilaterally and is an essential component of efficient bipedal movements such as walking, running, and jumping. The anatomical function and stability of the knee depend on muscles, bones, ligaments, cartilage, synovial tissue, synovial fluid, and other connective tissues. The 4 main stabilizing ligaments of the knee are the anterior cruciate (ACL), posterior cruciate (PCL), medial collateral (MCL), and lateral collateral (LCL). The ACL attaches at the lateral condyle of the femur and the intercondyloid eminence of the tibia, and functions to prevent anterior translation of the tibia on the femur. The PCL attaches at the medial condyle of the femur and the posterior intercondylar area of the tibia, and functions to prevent forward displacement of the femur on the tibia.The MCL attaches at the medial epicondyle of the femur and the medial condyle of the tibia, and functions to prevent valgus stress on the knee. The LCL attaches at the lateral epicondyle of the femur and the head of the fibula, and functions to prevent varus stress on the knee. The medial and lateral menisci are 2 separate fibrocartilage structures that are located between the articular surfaces of the tibia and femur. They function as shock absorbers, static stabilizers, and friction reducers during articulation. The knee’s bony structures include the distal end of the femur, proximal end of the tibia, and patella. The patella is the largest sesamoid bone in the body and functions as an attachment point for the quadriceps tendon and patellar ligament. It also protects the anterior articular surface of the femoral portion of the knee. The knee contains multiple bursas which serve to reduce friction between structures of the knee. Bursas are small sacs made up of synovial membranes and contain synovial fluid. Many of these structures mentioned above are part of the articular capsule which serves to stabilize the knee further and contain synovial fluid. Synovial fluid is made by synovial membranes and serves to reduce friction between articular surfaces of the knee.