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"
Tuberosity of the tibia Tuberosity of the tibia The tuberosity of the tibia or tibial tuberosity or tibial tubercle is a large oblong elevation on the proximal, anterior aspect of the tibia, just below where the anterior surfaces of the lateral and medial tibial condyles end. It gives attachment to the patellar ligament, which attaches to the patella from where the suprapatellar ligament forms the distal tendon of the quadriceps femoris muscles. The quadriceps muscles consist of the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. These quadriceps muscles are innervated by the femoral nerve. The tibial tuberosity thus forms the terminal part