KNEE ANATOMY

The knee is the largest joint and one of the most important joints in the body. It plays an essential role in movement related to carrying the body weight in horizontal (running and walking) and vertical (jumping) directions. The knee is a modified hinge joint, a type of synovial joint, which is composed of three functional compartments: the patellofemoral articulation, consisting of the patella, or "kneecap", and the patellar groove on the front of the femur through which it slides; and the medial and lateral tibiofemoral articulations linking the femur, or thigh bone, with the tibia, the main bone of the lower leg. The joint is bathed in synovial fluid which is contained inside the synovial membrane called the joint capsule.

The knee is made up of the following;

     
• Bones. Three bones meet to form your knee joint: your thighbone (femur), shinbone (tibia), and kneecap (patella).   
     
• Articular cartilage. The ends of the femur and tibia, and the back of the patella are covered with articular cartilage. This slippery substance helps your knee bones glide smoothly across each other as you bend or straighten your leg.   
     
• Meniscus. Two wedge-shaped pieces of meniscal cartilage act as "shock absorbers" between your femur and tibia. Different from articular cartilage, the meniscus is tough and rubbery to help cushion and stabilize the joint. When people talk about torn cartilage in the knee, they are usually referring to torn meniscus.   
     
• Ligaments. Bones are connected to other bones by ligaments. The four main ligaments in your knee act like strong ropes to hold the bones together and keep your knee stable.   
        
           
• Collateral Ligaments.  These are found on the sides of your knee. The medial collateral ligament (MCL) is on the inside of your knee, and the lateral collateral ligament (LCL) is on the outside.  They control the sideways motion of your knee and brace it against lateral collapse and movement.      
           
• Cruciate ligaments. These are found inside your knee joint. They cross each other to form an "X" with the anterior cruciate ligament (ACL) in front and the posterior cruciate ligament (PCL) in back. The cruciate ligaments control the back and forth motion of your knee.      
        
     
• Tendons. Muscles are connected to bones by tendons. The quadriceps tendon connects the muscles in the front of your thigh to your patella. Stretching from your patella to your shinbone is the patellar tendon.