Joint locking (medicine) symptom of: Locking of the knee happens during the last stages of extension when a person is standing up. Medial rotation of femur occurs as the space available at the lateral condyle of tibia is being used up by the lateral condyle of femur during extension. Therefore, lateral femoral condyle acted as an axis for medial femoral condyle to rotate backwards. This movement is aided by oblique pull of the ligaments of the knee joint and contraction of the quadriceps muscles. The ligaments are pulled taut when the knee joint is locked in place during standing. When the knee is
Ball and socket joint the femur (ball) rests in the cup-like acetabulum (socket) of the pelvis, and in the glenohumeral joint of the shoulder, where the rounded head of the humerus (ball) rests in the cup-like glenoid fossa (socket) of the shoulder blade. The shoulder includes a sternoclavicular articulation joint. Ball and socket joint The ball and socket joint (or spheroid joint) is a type of synovial joint in which the ball-shaped surface of one rounded bone fits into the cup-like depression of another bone. The distal bone is capable of motion around an indefinite number of axes, which have one common center. It