 Good day everybody. Welcome to our dissection of the pasture compartment of the leg and I'm Sanjay Sanyal, Professor Department Chair. First we'll demonstrate the muscles which are in the superficial compartment of the pasture compartment of the leg. So the muscle that we see in front of us, this is the gastrochemius. It's got two bellies, the medial head and the lateral head. The cadaver is prone and this is the left leg. So this is the medial, this is the lateral, this is superior, this is inferior. The medial belly is slightly bigger than the lateral belly and the medial belly takes origin from the posterior surface of the, the medial condyle of the femur. The lateral belly takes origin from the posterior surface of the lateral condyle of the femur. If you notice the outer portions are more tendinous and the inner portions are more fleshy. The two bellies then unite and somewhere in the middle of the muscle they become a flat aponeurotic band and this aponeurotic band as it continues down it merges with the tendon of the soleus which I'm going to mention next and they form this tendons, this strong tough tendon which is called the tendo achilles or the tendo calcaneus. The medial belly as I told you is slightly bigger and this has got maximum clinical correlations. For example, it's a medial belly where the propritil artery runs very close to the and the medial belly is the one which can produce compression of the propritil artery in the condition known as propritil artery entrapment syndrome. The medial belly is the one which quite often snaps during excessive strain and it produces a very painful condition of the calf. I made an incision here around the aponeurosis to reflect the medial belly and the lateral belly of the gastrocnemius and we immediately see the next soleus muscle which is the third component of the tricep sure. The two heads of the gastrocnemius and the soleus together constitute the tricep sure. Soleus comes from the word flatfish because it is like a flatfish and we can see straight away that the attachment of the soleus is like an inverted U. Laterally it is attached to the posterior surface of the fibula and medially it is attached to the posterior surface of the tibia and these are respectively referred to as the solial lines and between the fibula and the tibia there is a gap and this gap is bridged by a fibro structure which is referred to as the tendinous arch of soleus and under this tendinous arch of soleus we have the propritial structures entering. The gastrocnemius and the soleus tendons they fuse somewhere in the middle and they form this thick strong tough tendon which is known as the tendocalcaneus. So what is the difference between the gastrocnemius and the soleus components of the tricep sure? The gastrocnemius is for running, jumping, sprinting because it is type 2 white easily fatigable quick muscle and the soleus is for strolling. It is type 1 red postural slow not easily fatigable muscle and the two therefore have different functions. Another important functional aspect is that the gastrocnemius it takes origin from the femoral condyles and it gets inserted through the tenducalcaneus onto the calcaneus. So therefore the gastrocnemius acts on two joints it acts on the knee joint and it acts on the ankle joint. So therefore gastrocnemius is a two joint muscle in contrast the soleus is only a single joint muscle so that brings us to an important point. The gastrocnemius can flex the knee joint while both gastrocnemius and soleus together are the most powerful planter flexors of the ankle joint through the tenducalcaneus. However because the gastrocnemius is crossing the knee joint it cannot flex the knee joint and planter flex the ankle joints to the fullest extent together. Therefore if the knee is fully flexed then the gastrocnemius cannot planter flex. Okay that is about the functional aspect of it. So we have reflected the gastrocnemius and we look under the lateral head of the gastrocnemius we see yet one more muscle. We can see that muscle from outside above the lateral head of the gastrocnemius and once we lift it up we can see the same muscle under that also and this muscle that you see here this is the planteris muscle. The planteris muscle takes attachment from the lateral condyle of the femur above the lateral head of the gastrocnemius and it goes inside between the two heads and then it forms immediately forms a long thin tendon and this tendon runs between the gastrocnemius and the soleus it runs from lateral to medial and it merges with the tenducalcaneus. This planteris tendon does not have much functional importance but it has got some many anecdotal references and it has got some surgical use. First of all this is used for tendon transplant. Secondly this tendon can sometimes rupture during excessive use of the calf muscle and it can produce again a very painful condition of the calf and thirdly this is also referred very facetiously it is referred to as the fresh man's nerve because when dissecting the junior residents or the surgical residents sometimes mistake this tendon for the tibial nerve that's why it is also referred to as the fresh man's nerve because it looks very much like a nerve. So this is about the planteris. So these are the some of the aspects about the gastrocnemius and the soleus. These together constitute the tricep suri. Mind you the planteris is not included in the tricep suri. Now let me mention about the tenducalcaneus itself. The tenducalcaneus is arguably the most powerful tendon in the human body and it is the most powerful planter flexor. It starts from somewhere in the middle of the calf. First it starts as an aponeurotic sheet and then it rapidly becomes a very strong powerful tendon and we can feel the tendon on the back of our heel. As the fibers descend down it will look very closely you'll find that the turning fibers are turning laterally. The fibers which are superficial they are lateral and the fibers which are deep coming from the soleus they are more medial. Therefore as the tenducalcaneus descends down the fibers twist 90 degrees laterally such that the fibers which are coming from the gastrocnemius they are pointing laterally and the fibers which are coming from the soleus are pointing medially. This 90 degree twist is supposed to give extra springiness to the movements of the foot and the gait. Tenducalcaneus is such an important tendon that if it is ruptured then it is almost as bad as the foot getting cut. So therefore it has to be repaired and the procedure for repairing it is what was known as Z-plasty and that is what I have done. When I was cutting the calcaneus tendon I have cut it in the form of a small transverse limb a vertical limb and again a transverse limb with the opposite side. So when we are repairing it we do not repair it end to end we repair it like a Z-plasty. By so doing we ensure that the force the traction is distributed otherwise it will rupture again. It is done about one inch above the calcaneus it is inserted and then of course we have to repair the paratinone and I have cut a portion of the paratinone here to show the thin membrane which covers every tendon that is called the paratinone and the tenducalcaneus when it is inserted onto the back of the calcaneus there is a bursa under that which is known as a sub-tendinous bursa and there is also a bursa on the surface of the calcaneus which is known as a subcutaneous bursa. Both of these can be inflamed especially when we are wearing tight new shoes. So this is about the tenducalcaneus its clinical importance and its functional use. So this is about the superficial muscles of the posterior compartment of the leg. Thank you very much for watching ladies and gentlemen if you have any questions or comments put them in the comment section below Dr. Sanjay Sanyal signing out have a nice day. Like the video and make sure to subscribe.