 Good day everybody. Dr. Sanjo Sanyal, Professor Department Chair. So this is going to be a demonstration of the lower part of the back of the thigh, the propitial region, and the back of the leg. This is a prone cadaver. This is the left side. I'm narrating from the left side. The camera person is also on the left side. So we have the propitial fossa in front of us and the lower part of the thigh, which have been dissected out. The propitial fossa is a diamond-shaped depression on the back of the knee and it is bounded by these following structures. Supromedially, we have this combined muscle here. This is the semi-tendinosis and just under that, this is the semi-membrinosis. Suprolaterally, 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 supromedial and the suprolateral boundary respectively. Infromedially, we have this muscle here. This is the medial head of the gastrocnemius. Infrolaterally, 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 propitial fossa. This propitial 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 propitial fascia. The 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 propitial 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 propitial fossa to the other apex of the propitial 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 propitial vein and then we have this structure here. This is the propitial 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 propitial artery in the propitial fossa. The propitial artery gives five branches in the propitial fossa and for that we have separated the propitial vein completely and lifted up the propitial 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 propitial artery in the propitial fossa. Then we have this branch here. This is the middle genicular artery. Then we have this branch here. This is the inferior lateral and this is the inferior medial genicular branch of the propitial artery. So these are the five branches of the propitial artery in the propitial fossa and they are accompanied by their respective veins some of which has been removed just for better clarity. These genicular arteries, they also anastomose among themselves and they also anastomose with a descending branch of the femoral artery or 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, propitial occlusion. The 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 through the adductor hiatus they become known as the propitial vein and the propitial artery. This is the place where one of the sites where the propitial artery can potentially be entrapped producing propitial artery occlusion. The next point I want to draw your attention to is as the propitial 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 propitial artery entrapment syndrome PAES. And according to the love and valent classification there are six different types of propitial 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 is yet a third site of potential entrapment of the propitial 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 extravestition of synovial fluid from the knee joint or from one of the bursae around the knee joint like for example the semi-membranosis bursa or the gastrocnemius bursa or even the propitial bursa then the synovial fluid can collect in this space in the propitial fossa because there is a potential large space for collection and then it forms a fluctuate swelling and that is referred to as a propitial cyst or a morant baker cyst. Rarely we can get aneurysm of the propitial 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 propitial fossa and its contents. Before we conclude there are a few other structures I want to mention which are indirectly related to the propitial fossa. We can see this vein and this is the tributary of that vein. This vein comes on the back of the leg. It starts on the lateral aspect of the foot and it continues on the back of the leg and it comes on the superficial fascia. This is the short syphilis vein and this short syphilis vein then pierces the propitial fascia and it opens into the propitial vein. This short syphilis vein is a very useful landmark vein because we can see that it is accompanied by this nerve here and this nerve. This is the sural nerve. The sural nerve is a cutaneous nerve on the back of the leg. Sura means calf and it is formed by a branch from the tibial nerve called the medial sural cutaneous nerve and a branch from the common fibular nerve which is known as the lateral sural cutaneous nerve. So a communication from the lateral sural cutaneous nerve and the medial sural cutaneous nerve both of them unite to form the sural nerve and this sural nerve then runs down and it supplies the skin on the back of the calf. This sural nerve can be used for nerve drafting, for example an injured facial nerve during penultimate surgery and in order to identify the location of the sural nerve we use this short syphilis vein as a landmark. There are lymph nodes here which are referred to as the propitial nodes therefore if there is any infection of the back of the leg or the lateral side of the foot they all drain via the lymphatics along the short syphilis vein to the propitial nodes. While we are on the topic of the short syphilis vein and the sural nerve I would like to draw your attention to yet another though not located in the propitial fossa and that is this vein here. We can see this vein running on the medial side of the thigh and running on the posterior medial aspect of the knee. This is the long syphilis vein in this particular cadaver it is highly thrombosed and it was very brittle part of it has been ruptured. So this is the upper part of it this is the lower part of it. This long syphilis vein it runs on the medial side of the leg from the medial side of the foot it climbs up it goes 100 behind the anterior aspect of the knee and then it runs on the medial side of the thigh and it opens into the femoral vein through the syphilis opening. So this is the long syphilis vein this is used for veneer section veneer puncture and it is also used for coronary artery bypass grafting. So these are some of the other structures that we can see in relation to the propitial fossa. Thank you very much for watching. Dr. Sanjay Sanyal signing out. Mr. Kendal Kambor batch is the governor person. If you have any questions or comments please put them in the comment section below. Have a nice day.