The genesis of the popliteal tendon and the ‘climb’ of the popliteus muscle

Object of Study The genesis of the popliteal tendon and the ‘climb’ of the popliteus muscle Summary of Results The present adult morphology of the postero‐lateral aspect of the knee joint requires a good understanding of the evolutionary origin of the popliteal tendon. The popliteus muscle and its tendon originate separately. During evolution they get connected in the way that they are seen in humans. This tendon is not present in reptiles. This work provides proof of the genesis of the popliteus tendon and delineates which of its surrounding structures it evolved from. Origins of the arcuate popliteal ligament and the short lateral ligament are also discussed. Statement of Conclusions In lower vertebrates (birds, reptiles and amphibians) there are separate femorotibial and femorofibular joints with separate femorofibular and femorotibial menisci. Both menisci have corresponding meniscal ligaments to the femur above and the fibula and tibia below. The popliteus muscle exists in these lower vertebrates but has no femoral attachment. As evolution progresses the femorofibular joint and its related structures disappear and the fibula recedes from its femoral attachment to a newer and lower attachment on the upper tibia through the proximal tibiofibular joint. The femorofibular meniscus and it's meniscofemoral ligament (which are remnants of the primitive femorofibular joint) get connected as a continuous tendon to the main body of the popliteus muscle. Thus the popliteus gets a new femoral attachment it did not have initially. The popliteus ‘climbs up’ from a sub‐genual position to a newer supra‐genual one aiding upright walking in humans. Crucially, the formation of its tendon is aided by remnants of the femorofibular joint structures which undergo evolutionary recession. Grant Funding Source : Self