Knee joint. Macro photograph of a section through the knee joint of a young child. Bones are pale purple, ligaments are dark purple and muscle is brown. This section goes through the base of the femur (thigh bone). The bones seen at right and left are the rounded protrusions, or epicondyles, at the end of the bone. The femur articulates with the tibia (shin bone) to form the knee joint. At top centre is the knee cap (patella). At centre are the anterior (left) and posterior (right) cruciate ligaments, bands of strong, flexible connective tissue. These ligaments connect the femur to the tibia and maintain the stability of the knee. Magnification: x2 when printed at 10 centimetres wide.