The knee is made up of 4 bones and an extensive network of ligaments and muscles.
The four main bones:
- Femur (thigh bone) – the longest and the largest bone in the body, part of the hip joint and part of the knee joint
- Tibia (shinbone, shankbone) – is the larger and stronger of the two bones int the leg below the knee, and connects the knee with the ankle bones.
- Fibula (calf bone) – is placed on lateral side of the tibia, with which it is connected above and below, and forms the lateral part of the ankle joint
- Patella (knee cap, kneepan) – is a thick bone, which articulates with the femur and covers and protects the anterior surface of the knee joint.
Knee cartilage – Menisci (medial and lateral)
The bone ends are covered with cartilage. Function of cartilage is to provide a smooth surface, acts as a shock absorber. Each knee joint has two crescent –shaped cartilage menisci. These lie ont he medial and lateral edges of the upper surface of the tibia bone.
The two main muscle groups of the knee: The two main muscle groups of the knee joint are the quadriceps and the hamstrings. Both moving and stabilizing the knee joint.
- The Quadriceps is a group of 4 muscles: rectus femoris, vastus lateralis, vastus intermedius, vastus medialis, that sit in the front of the knee. The quadriceps attach to the front of the tibia and originate at the top of the femur. This muscle group acts extend the leg while straightening the knee.
- The Hamstrings are comprised of 3 separated muscles: biceps femoris, semitendinosus, semimembranosus. The Hamstrings are located on the back of the knee.
The ligaments of the knee:
- The Anterior cruciate ligament (ACL) – the main ligaments in the knee. It connects the Femur to the Tibia. The role of the ACL is to prevent foward movement of the Tibia from underneath the Femur.
- The Posterior cruciate ligament (PCL) – It connects the Femur to the Tibia. The PCL prevents movement of the Tibia in backwards direction.
- The Lateral collateral ligament (LCL) – is the knee ligament that is located on the outside (lateral aspect)) of the knee that links the thigh bone (Femur) and the shin bone (Tibia).
- The Medial collateral ligament (MCL) – is the knee ligament that is located on the inside (medial aspect) of the knee that links the thigh bone and the shin bone.
The knee is a mobile trocho-ginglymus joint. The principal movements occuring at this joint are flexion and extension, but some rotation also occurs int he flexed position.