 So this is going to be a demonstration of the Tricep Suri. This is a prone caregiver. We are demonstrating on the left leg The camera person is on the right side. The Tricep Suri, Gastrofemius and Solius, they are what constitutes the superficial compartment of the posterior compartment of the leg. The posterior compartment of the leg is covered by a fascia which we have removed here and the fascia is attached medially to the medial bone of the tibia which is felt here and then it goes all the way down and here on the lateral side it gets attached to posterior intramuscular septum which gets attached to the posterior margin of the fibula. So between the posterior intramuscular septum and the fascia which gets attached to the tibia this compartment is the posterior compartment and located in the posterior compartment we have the superficial group of muscles which are the tricep suri and the deep group of muscles which I am going to demonstrate in another video. The tricep suri typically involves the two heads of the gastrofemius and the Solius. Some textbooks include the plant arrays also in the tricep suri. Let's start off with the gastrofemius which is visible in front of us. This is a high resolution still shot from the dissection to show the two heads of the gastrofemius. The gastrofemius as the term implies has two bellies. This is the medial belly and this is the lateral belly. The medial belly and the lateral belly they constitute the infromedial and the infolateral boundaries of the parietal fossa and we can see that very clearly here. The medial belly is a larger belly and it takes origin from the posterior aspect of the medial content of the femur and then it continues down and we can see inner portion of the tender of origin is aponeurotic. The lateral belly is a little smaller it takes origin from the lateral content of the femur and we here also we can see that the lateral portion is slightly aponeurotic. The two bellies then converge and they form the gastrofemius and approximately midway down the length of the calf they become aponeurotic and the aponeurosis then rapidly converges and becomes the tendocalcaneus. The medial belly has got a bursa between the medial belly and the semi-membranosis and we can see that bursa here. This is known as the semi-membranosis bursa which can communicate with the knee joint. There is also a bursa between the medial belly and the point where it takes origin from which also communicates with the knee joint and that is known as gastrofemius bursa. The medial belly is notorious for producing many clinical complications. One of them is it can produce entrapment of the publital artery because the publital artery is very close to the medial belly and it can either go under the medial belly or the medial belly may overlap the publital and that condition is known as publital artery entrapment syndrome. Actually, publital artery entrapment syndrome is a big classification involving six subtypes. Medial belly is also responsible for rupture at times especially during well played tennis and that can produce a very painful calf condition known as tennis leg. What is the function of the gastrofemius? The gastrofemius is a two joint muscle. It is crossing the knee joint and by virtue of its attachment to the tendocalcaneus it also crosses the ankle joint. So therefore it is a flexor of the knee and it is a very powerful plantar flexor. It cannot do both the functions together simultaneously. So therefore if the leg is completely flexed at the knee then the gastrofemius cannot plantar flex the foot. Gastrofemius is type 2, white, fast twitch, easily flittigable muscle. So therefore we run, jump and spring with the gastrofemius that is the classical way of describing it. Now I am going to reflect the gastrofemius, just the gastrofemius alone. We have cut it where it is getting attached to the tendocalcaneus and we are reflecting it up. Once we reflect it up now we can see the under surface of the gastrofemius in the two bellies and we can see the neurovascular structures going to the muscle belly itself. What we see under in front of us now is the neck structure of the tricep sureg and that is the soleus. The soleus is a flat muscle. In fact the word soleus means flat fish. It resembles the fish which is found lying at the bottom of the ocean. The soleus takes origin in an inverted U shaped fashion from the posterior aspect of the tibia and it goes up and then from the posterior aspect of the fibula. So this is the U shaped attachment. In between the tibia and the fibula there is a gap which is bridged by a tendinous arch and that is known as the tendinous arch of soleus. This tendinous arch of soleus gives passage to these neurovascular structures that we can see here. We can see the popliteal artery which is passing down the popliteal vein and the tibial nerve and from here the popliteal artery divides into an anterior tibial and posterior tibial vein also divides and the tibial nerve continues straight down on the back of the leg. The artery and or the vein can get entrapped here under the tendinous arch of soleus and this is the third side of entrapment of the popliteal artery in relation to the popliteal osso. So this is the origin of the soleus and the soleus also then continues down and it merges with the tendon of the gastropneumius and it forms the tendo achilles or the tendo calcaneus. What is the function of the soleus? The soleus is type 1 red muscle not easily fatigable, slow twitch so therefore it is a posterior muscle. It is used for strolling or standing at attention for long duration of time. Soleus is the one joint muscle so therefore it acts only on the anchor joint through the tendo calcaneus so therefore it contributes to the powerful plant reflection only. Now let's come to the third muscle. This is the plantaris muscle. It takes origin from the lateral cornel of the femur above the lateral belly of the gastropneumius and we can see it here and when I turn this we can see the rest of the muscle coming down here and then rapidly it becomes a very thin long tendon and it goes from lateral to medial between the gastropneumius and the soleus and then it merges with the tendo calcaneus. This does not have much functional use however this has got some anecdotal stories pertaining to it. This is sometimes specifically referred to as the fresh man's nerve because a surgical resident or a fresh man when he or she is dissecting sometimes they mistake this for the tibial nerve that's why this is called the fresh man's nerve. This is a useful structure for tendon rafting just like the parmesan was in the hand and sometimes even this tendon can rupture while playing tennis and can produce a painful calf condition and that is also known as tennis leg. In fact earlier tennis leg was attributed only to rupture of the plantaris tendon but recent studies have shown that more often it is due to rupture of the medial belly of the gastropneumius. So these are the structures which I wanted to show you in the triceps suring. Thank you very much for watching. If you have any questions or comments please put them in the comment section below. Dr. Sanjeev Sanyal signing out. Have a nice day.