Knee anatomy. Artwork of the bones and ligaments of a normal human knee. The knee joint is where the upper leg bone (femur, top) articulates with the tibia (shin bone, bottom). At right is the smaller of the lower leg bones, the fibula. The patella (knee cap, centre) covers and protects the joint. There are four main ligaments, the bands of tissue connecting the bones. At right and left are the medial collateral ligament and the lateral collateral ligament. At centre are the anterior (front) and posterior (rear) cruciate ligaments. This is a left knee, seen from the front.