 Good day everybody, Dr. Sajja Sanyal, Professor's Department Chair. This is going to be a demonstration of the superficial muscles in the calf. So this is the prone catamber, this is the left side. The narration and the camera person, both are from the left side. So we can see the superficial calf muscles on the left side here. This is the gastropemius. The term gastro means bellies, therefore the gastropemius has got two bellies, and this is the one which gives the rounded appearance of the calf. So this is the medial belly. And we can see it takes origin from the posterior aspect of the medial femoral condyle. And it merges with the lateral belly. The lateral belly takes origin from the posterior aspect of the lateral femoral condyle. And the two of them, somewhere in the middle of the calf, they become a flat aponeurotic sheet. And this aponeurotic sheet then rapidly converges and becomes the tendocalcaneus. The tendocalcaneus then gets inserted onto the posterior aspect of the calcaneus. The action of the gastropemius. The gastropemius, because it takes origin from the femoral condyle, it has got a weak action of flexion of the knee. But the most important action of the gastropemius is plantar flexion of the foot through the tendocalcaneus. However, the gastropemius cannot perform both the actions simultaneously to the full extent. In other words, if the knee is fully flexed, then the gastropemius does not participate in plantar flexion. The gastropemius is type 2 white muscle fiber, fast twitch, easily fatigable. Therefore, it is used for running, jumping and doing all sorts of vigorous activity because it gets rapidly fatigued. The medial belly of the gastropemius, as you can see, is a little larger than the lateral belly. The medial belly is the one which is responsible for maximum number of clinical correlations. The medial belly can sometimes entrap a popliteal artery. Either because the popliteal artery is too close to the medial belly, or an abnormal origin of the medial belly compresses the popliteal artery, or an abnormal slip from the medial belly compresses the popliteal artery. These are all various constellation of syndromes which are referred to as the popliteal artery entrapment syndrome. The medial belly can be responsible for pain in the calf, and the medial belly can also sometimes rupture in the condition known as tennis leg. Between the medial belly and the posterior aspect of the femoral condyle, there is a bursa, and that is referred to as the gastropemius bursa, which communicates with the knee joint. Similarly, between the medial belly and the semi-membranous muscle which is shown here, there can be a bursa, and that is referred to as a semi-membranous bursa. This is the x-ray of the knee to show a sesame bone under the lateral head of the gastropemius called the febela. I've cut the medial belly here, and I've cut the lateral belly here, added its attachment to the tendocalcaneus, and I'm going to reflect. And when we reflect, we can see the under surface of the gastropemius, and we can see the various branches from the tibial nerve are supplying the gastropemius. The muscle that comes in front of us after reflecting the gastropemius, this is the soleus. The word soleus means flatfish, because it resembles a flatfish that is seen at the bottom of the ocean lying on its side. Origin of the soleus. The soleus takes origin from an inverted U-shaped line, and we can see that inverted U-shaped line on the posterior aspect of the tibia here. This is called the solial line. So attached to the solial line and below that is the soleus. And attached above the solial line is this muscle here, which is the poverty case. This solial line curves up like this, and then it forms a tendinous arch. We can see it here, which bridges from the tibia to the fibula, and this is the tendinous arch. This is referred to as the tendinous arch of soleus. And then the attachment continues on to the posterior aspect of the fibula as we can see here, and then it comes down on the posterior aspect of the fibula here like this. So therefore the origin of the soleus is an inverted U-shaped. The insertion of the soleus is along with the gastropemius to the tendocalcaneus, and we can see that very clearly here. From here the tendon becomes rapidly tendinous and it becomes known as the tendocalcaneus, which I shall describe just now. The action of the soleus. The soleus is the most powerful plant reflection through the tendocalcaneus. The soleus is type 1 red muscle fibre. It is slow twitch, it is not easily fatigable, and therefore it is used for strolling. So therefore we say we stroll with the soleus and we run and jump with the gastropemius. The soleus, unlike the gastropemius, is a one joint muscle because it does not cross the knee joint, it crosses only the ankle joint. Sometimes there can be an accessory fibre of the soleus, and that can be responsible for a painful ankle condition in excessive use of the soleus. Now we can see yet one more muscle between the gastropemius and the soleus, and this one here. We can see it is taking origin from above the origin of the gastropemius lateral belly. This is the muscle here, and this is the lateral belly. So I have reflected it here to see this muscle. This is the plantaris muscle. The plantaris muscle rapidly becomes a thin, long tendon, narrow tendon, which moves from the lateral to the medial side between the gastropemius and the soleus, and it merges with the tendocalcaneus tendon. This plantaris tendon does not have much functional use, however it is used for tendon grafting whenever it is required. It is also referred to as the fresh man's nerve, because when a resident surgeon, when he is dissecting here, he may mistake this for the tibial nerve. That's why facetiously it is also referred to as the fresh man's nerve. Sometimes this plantaris tendon can rupture with a painful snap while playing, and this is also one of the conditions which is responsible for the so-called tennis leg. However nowadays it is believed that it is more often due to rupture of the medial belly of the gastropemius which I mentioned earlier. So that brings me to the concept of what is known as the triceps sure. The triceps sure refers to the two heads of the gastropemius and the soleus together forming the tendon. This is the triceps sure. Some books say that triceps sure is composed of the gastropemius, soleus and the plantaris, but that concept is not really believed to be true because plantaris does not have much functional use. Now let me mention a few quick words about this tendocalcaneus. The tendocalcaneus is a very strong and a very powerful tendon and you can see it starts as an aponeurotic sheet. It's a combined fibers of the gastropemius, soleus and the plantaris, and it rapidly becomes a tendon and it gets inserted onto the back of the calcaneus. There can be a bursa deep to the tendocalcaneus and that is known as the deep calcaneal bursa. There can also be a bursa superficially which is referred to as a superficial calcaneal bursa to prevent friction. And this can be a cause of pain in bursa it is especially when wearing new shoes. This tendocalcaneus is the most powerful plantar flexor of the foot and it is due to the combined action of the gastropemius and soleus as I already described. This is a unique tendon because not only is it a powerful most powerful tendon in the human body, this is the only tendon which does not have its own sign of its sheep. Instead it is covered by this membrane which we have retained here on this side and on this side. This is referred to as paratinone. This paratinone is very important for the nutrition and for the well-being of this tendocalcaneus. If you look closely at the fibres of the tendocalcaneus, you will notice the fibres which are coming from the gastropemius. They are the superficial fibres and the fibres twist a little bit 90 degrees such that the fibres from the gastropemius they face laterally. Deep to that are the fibres of the soleus. They face medially. It is postulated that this twisting gives extra springiness and movement to the gait and to the action of plantar flexion. That brings me to a very important clinical correlation pertaining to the tendocalcaneus and that is rupture of the tendocalcaneus. When the tendocalcaneus ruptures it is as bad as cutting of the foot because the person cannot plantar flex the foot and therefore the person cannot walk. Therefore it is mandatory to repair the tendocalcaneus and we do it by means of a procedure which I have demonstrated here known as Z-plus. When the tendocalcaneus is cut, we have to convert it into a Z-shaped incision like we have shown here. We go approximately one and a half inches above this insertion and we convert the straight cut into a small horizontal cut, a longitudinal cut and again a small horizontal cut and this is called a Z-shaped incision. And thereafter each section of the cut is sutured separately by means of non-absorbable sutures. So one set of sutures will be here, another set of sutures will be here and a third set of sutures will be here. And after that it is mandatory to cover it up with the paratinoin and suture it and then after that POP cast has to be put above the knee joint to below the ankle joint for three months at least. The reason for doing this type of Z-plasty is to break the line of tension because if it is a straight cut and we try to suture it like that the tension will cause the sutures to give way. Therefore we break the line of tension by making it in the form of a Z and this is the way to ensure the integrity of the anastomosis of the tendon. So these are some of the facts which I want to mention to you about the triceps sure, the gastrointemius, soleus, plantaris and the tendocalcaneus. Thank you very much for watching Dr. Sanjay Sanyal signing out. David over the camera person if you have any questions or comments please put them in the comment section below. Have a nice day.