Bird feet and legs only a small extension of the cnemial crest. In grebes both a normal patella and an extension of the cnemial crest are found. The fibula is reduced and adheres extensively to the tibia, usually reaching two-thirds of its length. Only penguins have full-length fibulae. The bird knee joint between the femur and tibia (or rather tibiotarsus) points forwards, but is hidden within the feathers. The backward-pointing "heel" (ankle) that is easily visible is a joint between the tibiotarsus and tarsometatarsus. The joint inside the tarsus occurs also in some reptiles. It is worth noting here that the name "thick knee"
Stifle joint stabilized by paired collateral ligaments which act to prevent abduction/adduction at the joint, as well as paired cruciate ligaments. The cranial cruciate ligament and the caudal cruciate ligament restrict cranial and caudal translation (respectively) of the tibia on the femur. The cranial cruciate also resists over-extension and inward rotation, and is the most commonly damaged stifle ligament in dogs. 'Cushioning' of the joint is provided by two C-shaped pieces of cartilage called menisci which sit between the medial and lateral condyles of the distal femur and the tibial plateau. The main biomechanical function of the menisci is probably to divide