 So this is going to be a demonstration of the lower part of the back of the thigh, the perpendicular region and the back of the leg. This is a prone cadaver, this is the left side. I am narrating from the left side, the camera person is also on the left side. So we have the perpendicular fossa in front of us and the lower part of the thigh which have been dissected out. The perpendicular fossa is a diamond shaped depression on the back of the knee and it is bounded by these following structures. To promediately, we have this combined muscle here, this is the semi-tendinosis and just under that this is the semi-membrinosis. Supralaterally, we have this combined muscle here. This is the combined muscle of the short and the long head of the bicep femoris. So therefore, this is the supramedial and the supralateral boundary respectively. Inframedially, we have this muscle here, this is the medial head of the gastrocnemius. Infralaterally, we have this combined muscle here, this one is the plantaris muscle and just under that this is the lateral head of the gastrocnemius. So therefore, this is the perpendicular fossa. This perpendicular fossa was covered by a thick fascia which is actually the continuation of the fascialata continuing into the crural fascia and this portion of that deep fascia is referred to as the popliteal fascia. Superficial to that was the superficial fascia of the leg. We have removed that to show the content. The content was completely filled with fat and lymph nodes and those have been removed to show the depth of the perpendicular fossa. So let's take a look at the other important contents. We can see this nerve here. This is the sciatic nerve coming from the thigh and the sciatic nerve divides in the lower part of the thigh into a tibial division which runs straight down from one apex of the popliteal fossa to the other apex of the popliteal fossa. And we can see that doing and this is the common fibular nerve which runs laterally obliquely under cover of the bicep femoris and then it goes behind the head of the fibula and then it winds around the lateral to the neck of the fibula. So this is the first structure which is a content. Then we have this structure which I have lifted up here. This is the popliteal vein and then we have this structure here. This is the popliteal artery. So therefore the rule of thumb is from lateral to medium and from superficial to deep. We have the nerve vein artery. So this is a very useful relationship to remember. Now let's show the branches of the popliteal artery in the popliteal fossa. The popliteal artery gives five branches in the popliteal fossa and for that we have separated the popliteal vein completely and lifted up the popliteal artery. We can see this artery here and we can see this artery here. This is the superior lateral and this is the superior medial genicular artery which are the branches of the popliteal artery in the popliteal fossa. Then we have this branch here. This is the middle genicular artery and then we have this branch here. This is the inferior lateral and this is the inferior medial genicular branch of the popliteal artery. This is the right femoral popliteal angiogram to show some of the branches of the popliteal So these are the five branches of the popliteal artery in the popliteal fossa and they are accompanied by the respective veins, some of which has been removed for better clarity. These genicular arteries also anastomose with a descending branch of the femoral artery for the genicular branch of the femoral artery and they also anastomose with a branch from the lateral circumflex femoral and they also receive a recurrent branch from below and all these eight arteries they constitute what is known as the genicular anastomosis. This genicular anastomosis provides collateral circulation in femoral popliteal occlusion. Next important point which I want to draw your attention to is this opening where my instrument is going in and I can put my finger also. This is the adductor hiatus. The adductor hiatus is an opening between the two parts of the adductor Magnus, the adductor component and the hamstring component and this adductor hiatus gives passage to the femoral artery in the femoral vein as they pass out to the adductor hiatus they become known as the popliteal vein and the popliteal artery. This is the place where one of the sites where the popliteal artery can potentially be entrapped producing popliteal artery occlusion. The next point I want to draw your attention to is as the popliteal artery descends down it is situated as you can see very close to the medial head of the gastrocnemius and it can potentially be compressed by the medial head of the gastrocnemius and that constitutes a constellation of syndromes which are collectively referred to as the popliteal artery entrapment syndrome P-A-E-S and according to the love and valent classification there are six different types of popliteal artery entrapment and they are all directly or indirectly related to the medial head of the gastrocnemius though of course there are a few other variations also there's yet a third site of potential entrapment of the popliteal artery but that is not present in this particular dissection. In dislocation of the knee joint posterior dislocation especially it can potentially injure the tibial nerve or any of the other structures. When there is extra position of synovial fluid from the knee joint or from one of the per se around the knee joint like for example the semi-membranouss bursa or the gastrocnemius bursa or even the popliteal bursa then the synovial fluid can collect in this space in the popliteal fossa because there's a potential large space for collection and then it forms a fluctuating swelling and that is referred to as a popliteal cyst or a morant baker cyst. This is an MRI of the knee to show the femoral condyles and the morant baker cyst in the popliteal fossa. Really we can get aneurysm of the popliteal artery in which case it will produce an expansile pulsation on the back of the knee so these are some of the important clinical correlations pertaining to the popliteal fossa and its contents. That's all for now thank you very much for watching Dr. Sanjay Sanyal signing off please like and subscribe if you have any questions or comments please put them in the comment section below. Have a nice day.