 So this is going to be a demonstration of the muscles of the posterior compartment of the leg. This is a prone cadaver This is the right side right calf. I'm demonstrating from the right side camera person is on the left side So let's start off with the first muscle that we can see the superficial compartment of the posterior compartment of the leg This muscle that we see here. This is the gastrocnemius The gastrocnemius is about two bellies The first belly is this one here This is the lateral belly of gastrocnemius Takes origin from the posterior surface of the lateral condyle of the femur This is the medial belly of the gastrocnemius takes origin from the posterior surface of the medial condyle of the femur And the two bellies then converge this forms the bulk of the calf muscle the rounded appearance of the calf muscle And somewhere in the middle it becomes a poneurotic and thereafter it rapidly converges into a thick strong Tendon which I shall describe later. This is the tendo calcaneus earlier known as tendo killies Let's mention a few quick words about the gastrocnemius the medial belly is slightly larger than the lateral belly The medial belly is the one which has got the maximum number of clinical correlations. There's a bursa between the This muscle here. This is the semi-membranosis bursa Which is located between the semi-membranosis muscle and the medial belly Likewise under the medial belly and the knee joint there can be a bursa which communicates with the knee joint And that is known as the gastrocnemius bursa. So there are two bursae in relation to the medial belly Painful rupture of the medial belly is called tennis leg The medial belly can also be responsible for entrapment of the Puppletial artery and we can see this is the Puppletial artery here And it is running very close and almost under the medial belly abnormal origin of the medial belly Or abnormal location of the Puppletial artery can produce entrapment of the Puppletial artery Which is referred to as the Puppletial artery entrapment syndrome Rarely there can be a smart bone within the lateral head of the gastrocnemius, which is known as favela Now let me reflect the gastrocnemius to show the muscle under the gastrocnemius We are still in the superficial compartment. So I have reflected the gastrocnemius It has been cut here and we can see this is the cut section of the gastrocnemius the proximal portion The distal portion has fused with the tendocalcaneus the muscle that we see here This is the soleus the soleus is called soleus because it is like a flat fish Let's take a look at the origin of the soleus The soleus takes origin in an inverted V-shaped fashion and we can see that inverted V-shaped One lip of the V is on the posterior surface of the tibia here The other lip of the V is in the posterior surface of the fibula here and between the tibia and the fibula There is a fibrous arch and that is referred to as the tendinous arch of soleus and my finger has gone through the tendinous arch of soleus this tendinous arch of soleus is the place where the tibial nerve the Populatial vein and the populatial artery they pass into the leg and this is a potential site of entrapment of the populatial artery again We have cut the tendocalcaneus here And I will show you the precise method that we use for repair at a later stage in the dissection Let me reflect the whole tendocalcaneus and now we can see the soleus from the under surface So again to put it back This is the gastropneumius and this is the soleus and this is the combined tendon of the gastropneumius and soleus Here we can see a few extra muscle fibres of the soleus Sometimes these muscle fibres are very prominent and the textbooks refer to this as the Accessory soleus which can be a cause of a painful calf condition in excessive use of the leg So what is the difference between the action of the gastropneumius and the soleus? Both of them are powerful plant reflexes of the foot through the tendocalcaneus But the difference is the gastropneumius is a two joint muscle it takes origin from the condyle of the femur and gets inserted on to the Calcaneus bone through the tendocalcaneus So therefore it helps to flex the knee joint and plant reflex the foot But you cannot do both actions together simultaneously to the fullest extent in other words if the knee is fully flexed Then the gastropneumius cannot plant reflex the foot Gastropneumius is a type 2 white muscle. It is fast twitch easily fatigable So therefore we run jump the gastropneumius. The soleus on the other hand is a type 1 Red muscle slow twitch not easily fatigable. It's a posterior muscle. So therefore we walk slowly We stroll with our soleus. Soleus is only a one joint muscle. It acts only on the ankle joint It's only a powerful plant reflexor through the tendocalcaneus So these are the essential differences between the gastropneumius and the soleus Now let me mention a few quick words about the tendocalcaneus itself The tendocalcaneus is arguably the largest strongest and the most important tendon in the human body And we can see it is so thick and strong and powerful. It's a combined fusion of the gastropneumius Two bellies soleus and one more muscle, which I shall tell just a little later called the plantarix But that does not count. So the two heads of the gastropneumius and the soleus together constitute what is known as the triceps Suri. So therefore the tendocalcaneus is the tendon of the triceps suri and it gets inserted onto the posterior aspect of the calcaneus There can be a bursar deep to the tendocalcaneus and that is known as the Subtendinous bursar and there can be a bursar superficial which is referred to as the subcutaneous bursar Both these bursar can be inflamed especially the superficial one when we wear tight new shoes That brings me to the fibers of the tendocalcaneus. Now if you look very closely we find That the fibers coming from the gastropneumius the superficial fibers, they are moving a little laterally And concomitantly the fibers which are coming from the soleus, they move a little medially So therefore the fibers in the tendocalcaneus They twist by 90 degrees such that the gastropneumius fibers are facing laterally and the soleus fibers are facing medially This twisting of the fibers is supposed to give extra springiness to the gait and to the movement of the tendocalcaneus The tendocalcaneus is the only major tendon in the body which does not have a sign of will she instead it is covered by Only a thin layer of membrane which is referred to as the paratino and part of that we have retained here So that brings me to injury to the tendocalcaneus if the tendocalcaneus is accidentally cut Then it is as bad as cutting of the foot itself because the person will never be able to walk So therefore repair of the tendocalcaneus is mandatory Surgical repair the way we repair it is the way I have made an initiation on the tendocalcaneus So if it had been cut we convert the cut into a form of a z line That means we make a small horizontal line We make a longitudinal cut and make another horizontal one So this is called a z cut and then we have to repair the tendocalcaneus across Transversely and then again across using non-absorbable Suchips and then we have to repair the paratino on top of that The purpose of doing this is to if it had been a straight line incision then the Sucho line will give away So therefore we break the tension of the such a line by making a z cut and repair it Then this is called a z plus t and after that the patient has to be Immobilized from the knee to the foot Because that as I mentioned the gastropemia sticks origin from the femoral corn lines and then there after physiotherapy These are some of the principles of repair of the tendocalcaneus Which is a very important procedure in rapture of the tendocalcaneus now that I have lifted up the gastropemias We can see yet one more muscle here. This is the tendon of that muscle and this is the small muscle It is taking origin from the again lateral condyle posterior sphincter or the femur Under the lateral head of the gastropemias and we can see the other portion of the muscle here and We can face the muscle here It comes here and immediately after that it becomes long thin tendon and the tendon then moves from lateral to medial aspect Between the gastropemias and the soleus and it merges with the tendocalcaneus This is called the plantarism some books include the plantarism in the triceps Suray, but for all practical purposes. This does not serve any useful function anatomically So therefore this is used for tendon roughing in surgical practice Another clinical point is this can sometimes rupture with a painful snap especially while playing tennis rupture of this is also one cause of tennis leg and Finally, this is sometimes facetiously referred to as the Freshman's nerve Because a resident who's starting his clinical practice during surgery may mistake this for the tibial nerve And therefore this is referred to as the Freshman's nerve, but we know the tibial nerve is situated deep under the soleus So this is about the plantarism muscle So these are some of the points which I want to mention about the superficial muscles in the posterior compartment of the leg Thank you very much for watching Dr. Sanjay Sanyal signing out David O is the camera person If you have any questions or comments, please put them in the comment section below. Have a nice day