The knee joint consists of 3 separate parts, that together form a complex “hinge” joint which makes it into the largest synovial joint of the human body.
The unique structure of the hinge joint allows it to function as a fulcrum of both extensor and flexor muscles.
Movements
Most of the movements are controlled by the inferior part of the tibiofibular joint.
The main movements of the knee joints are flexion, extension and rotation (lateral and medial):
- Flexion- mostly by biceps femoris muscle
- Extension- mostly by quadriceps femoris muscle
- Rotation (when the knee is flexed)- lateral by biceps femoris muscle, medial by popliteus, sartorius and gracilis muscles.
The knee joint is stabilized by two joints:
- The patellofemoral joint
- The tibiofemoral joint
Joints
The knee joint is composed of three small joints, all are incapsulated by the synovial membrane:
- The superior tibiofubular joint - formed between the lateral condyle of the tibia and the head of the fibula
- The patellofemoral joint- formed by the patella bone attached to the femur on its anterior surface
- The tibiofemoral joint - formed between the proximal surface of the tibia and the condyles of the femur
Superior tibiofibular joint
The superior tibiofemoral joint is a synovial joint between the superior planes of tibia and fibula. Cartilaginous site with articulating surfaces surrounded by a fibrous capsule.
Articulating surfaces are different because the joint lining can be in an oblique or transverse position.