 Good day everybody. Welcome to our next dissection series. My name is Dr. Sanjay Sanyal and today at the base of our students I've decided to give a quick video demonstration of the functional and the surgical aspects of the calf region namely the trisepsury and the tendal calcaneus. I'm a surgeon by profession and I'm also a neuroscientist. This time I've decided to do a few surgical dissection videos. So let's take a quick look. This is a prone cadaver and what you see in front of you, the left leg has been dissected. This is basically a continuation of the dissection that we did previously on the calf region. This time we are dissecting out the calf region. The trisepsury includes as you can see in front of you the two heads of the gastrocnemius and the soleus underneath all of them inserting onto this tendon called the tendal calcaneus. So these three together constitute what is known as the trisepsury. TRI means three. SURE refers to the word calf. Before I go to the details, let me mention a quick word about testing of the trisepsury. The trisepsury, the main function is plantar flexion of the foot and therefore clinical testing involves asking the patient to plantar flexes foot against resistance or alternatively you can ask the patient to stand on his toes whereby the weight of the body will act as the counter traction and you will be able to test whether he has got plantar fission intact or not. So that's a few quick words about the trisepsury and its components. Now let's go a little deeper and let's take each component one by one. The gastrocnemius. Why is it called gastrocnemius? The gastrocnemius as because the word gastro means belly. The gastrocnemius includes two fusiform shaped muscles which look like bellies, two muscle bellies. That's why it's called the gastrocnemius. As you can see in front of you, it's got two heads, a medial head and a lateral head of the gastrocnemius. The medial head is slightly larger than the lateral head and one thing we notice is that the inner portions of the two heads are fleshy and the outer portions of the two heads are tendinous. Let's take a quick look at the origin of the medial head and the lateral head. The medial head takes origin from the the popular surface of the femoral condyle just above the femoral condyle, medial femoral condyle itself and the lateral head takes origin from the lateral surface of the lateral femoral condyle and the two heads then unite to form the calcaneus tendon. What is the main function of the gastrocnemius? The gastrocnemius, as you can see, it's crossing the knee joint and it's getting inserted on the ankle. It's got functions both on the knee joint and as well as the ankle joint. It functions as a flexure of the knee and also acts in plant reflection. However, it cannot perform both the functions to their fullest extent simultaneously. So therefore, the gastrocnemius can function to its best extent as a plant reflection only when the knee is fully extended and slightly dorsiflexed. Conversely, when the foot is when the knee when the knee is completely flexed, the gastrocnemius is incapable of producing plant reflection. So what is the functional role of the gastrocnemius? The gastrocnemius fibers are actually the white muscle fibers. They are the first twitch type of or type two muscle fibers which are easily fatigable. Therefore, the gastrocnemius is useful for running, jumping, sprinting. It is very only very intermittently used on sustained standing. Otherwise, most of its action is for quick work like running a jumping, as I mentioned to you. That's about the role of this gastrocnemius or the main function of the gastrocnemius muscle. Let's take a quick look at some clinical correlations pertaining to the gastrocnemius alone. As I told you, the medial partner belly is a larger one and most of the clinical correlations pertain to the medial belly. The origin of the medial belly is very close to the passage of the pulmonary artery and therefore the medial belly can sometimes produce compression of the pulmonary artery in what is known as the pulmonary artery entrapment syndrome. And as I mentioned in my previous dissection, pulmonary artery entrapment syndrome has got type one to type six out of which type two is due to a lateral migration of the medial belly at its origin and which can produce the compression of the pulmonary artery. Or in type three of the love and median classification, there's an abnormal fibrous muscular slip of the medial head of the gastrocnemius which can complies the pulmonary artery. Likewise, there's something called gastrocnemius strain, which is seen in people who are playing racket sports or tennis. There may be a partial rupture of the medial gastrocnemius fibers at its insertion to the tendocalcaneus and that produces a painful condition in the calf which is known as the tennis leg. So we can see most of the clinical correlations of the gastrocnemius pertaining to the medial belly of the gastrocnemius which is the larger belly and which is functionally more active. Now let's take a look at the muscle which is under the gastrocnemius. Here the gastrocnemius has been cut and partially reflected off and then you can see the soleus. Why is it called the soleus? It is a flat muscle and its sole refers to the flat fish which is found lying at the bottom of the seabed on its sides. That's why this has been called the soleus. The soleus takes origin in an inverted U-shaped fashion on the back of the leg. It runs on the back of the fibula, it goes up and it gets inserted and runs continuously on the back of the fibula and the tibia and in between the two there is a small fibrous arch which is known as the tendons arch of soleus. So that is the inverted U-shaped attachment of the soleus and inferiorly its fibres get first inserted onto the under surface of the aponeurosis of the genocalcinus which will later become tendinous which I shall mention a little later. So this is the soleus. Obviously the soleus does not take origin anywhere from the femur therefore it does not have any action on the knee joint. All its action is entirely concentrated on the ankle. It is the most important plantar flexor and it can act as a plantar flexor of the foot irrespective of the position of the knee unlike the gastrocnemius which could not perform any plantar flexion when the knee was flexed because it also had action on the knee joint namely flexion. Soleus is the most important. So what is the main functional use of the soleus? Soleus is the muscle which is useful for sustained standing, symmetrical standing because it is continuously the fibres are slow muscle fibres, they are red, they are slow twitch therefore they type one, they are fatigue resistant, they are anti-gravity, they are postural muscles therefore they prevent the tendency of the body to fall forward and therefore they are responsible for sustained action. This is the role of soleus. So therefore to summarize the actions of both these two together we say that we stroll with our soleus while we run, jump and sprint with our gastrocnemius. Soleus is for sustained use and gastrocnemius is for intermittent quick rapid use. There is not much important clinical correlation pertaining to the soleus per se because most of the clinical correlations will be pertaining to the tendocalconius which I shall mention just a little later. In a very small percentage of people there is an accessory soleus which forms a third belly way down at its insertion in the tendocalconius and then it produces a swelling medial to the tendocalconius that is called the accessory soleus and rarely it can produce a painful swelling when the leg is under constant use or heavy usage of the leg other than that the soleus per se does not have any important clinical correlations by itself. Before I come to the tendocalconius itself I decided that I am going to mention a few quick words about a small muscle which is sandwiched between the soleus deeply and the gastrocnemius superficially namely the plantaris muscle. The plantaris muscle takes origin from the lateral femoral supra condylar line just above the origin of the lateral head of the gastrocnemius and then the muscle quickly becomes tendinous and the long tendon then runs from lateral to the medial side and gets inserted on the tendocalconius. So this is the plantaris muscle. Functionally speaking the plantaris muscle does not have much use though a lot of muscle spindles have been identified in the plantaris muscle so therefore it may play some role in proprioception as we know muscle spindles are responsible for unconscious proprioception though the exact functional use is not very clear. Sometimes this plantaris tendon can rupture with a painful snap again during racket sports or playing tennis and can produce a painful condition of the knee and for beginners who are dissecting the leg sometimes they can mistake this long thing tendon as a nerve and therefore this has been facetiously referred to as the fresh man's nerve because this tendon does not have many functional use it can be used for tendon rafting for injuries of the hand. So these are the few quick words about the plantaris. Now let's come to the most important part and that is the tendocalconius itself. As I told you the tendocalconius is actually the common insertion for all these muscles the two heads of the gastrocnemius and of course the plantaris. The tendocalconius is perhaps arguably one of the most important tendons of the leg and perhaps the most important of the foot of the body itself and it's a very powerful tendon. It starts from somewhere midway in the calf as an aponeurosis and very quickly it becomes very deep and very strong tenderness and it gets inserted onto the posterior surface of the calcaneus. As it gets inserted it undergoes a 90 degrees lateral twist and this lateral twist is very significant. Because of this lateral twist the fibers which come from the gastrocnemius they come to be oriented laterally and the fibers which come from the soleus which were inserted onto the under surface of the aponeurosis initially and then becomes part of those tendocalconius the fibers of the soleus they come to be oriented immediately. It is said that this lateral 90 degrees twist is important for the point from the point of view of giving elasticity and springiness to our stance and gait. So that is the functional aspect about the tendocalconius of the tendocalconius. By the way for those of you who are interested in historical aspects have you ever wondered why it is called tendo achilles why it used to be called tendo achilles? Well according to the Greek mythology there was a Greek hero called Achilles who was the son of Pelius and Thetis. Somebody told his mother Thetis that if you dip your baby in the holy waters of the river Styx he will be invulnerable in battle and therefore she caught him by his ankles and dipped him and as luck would have it his whole body became invulnerable except his ankles because she held him by his ankles and during the battle of Troy he was shot by an arrow shot by Paris which hit him in his ankle and therefore he died from that injury. Today it is referred to as the weakest point in any human and any weakest point is referred to as the person's achilles heel. So that much about the historical aspect about why it is called tendo achilles but the more modern term is tendocalconius. Let's take a few quick look at some of the clinical correlations before we come to the most important one. The tendocalconius when it gets inserted into the calcaneus there are two per se in relation to this insertion. One is the subcutaneous bursa between the skin and the posterior surface of the calcaneus which is referred to as the subcutaneous calcaneal bursa and there is a deep bursa which is referred to as the sub tendinous calcaneal bursa between the tendon and the bone. Either or both of these bursa can get inflamed producing what is known as calcaneal bursitis. When we are wearing a tight shoe especially for the first time friction of the shoe with the back of the heel can produce the subcutaneous calcaneal bursitis and constant friction between the tendon and the bone can produce the sub tendinous calcaneal bursitis. All of them can produce painful conditions of the back of the heel. All of us know the use of tendocalconius for eliciting the planter reflex or the ankle reflex. When we tap it there is a quick planter twitch of the foot and that is dependent on the root values S1 and S2 and if the planter tendon reflex the knee ankle reflex is weak we say that the S1 S2 is weak. In people who are above the age of 40 or 45 years repeated usage and wear and tear of the tendocalconius print can produce a condition known as tend calcaneal tendinitis and then it can produce a chronic painful condition of the calf and the leg. That brings me to the next important clinical correlation and that is the calcaneal tendon rupture. The calcaneal tendon rupture can occur in one of two ways. One is if it's a continuation of the procedure of the condition known as calcaneal tendonitis then it occurs in usually old age and it can rupture and the other is when it can occur because of some traumatic injury. Then it can occur of course in any age group but it usually happens in young adults. The most common site of rupture of the tendocalconius is approximately 1 to 5 centimeters proximal to its attachment to the calcaneus and when such a thing happens it produces a painful lump in the middle of the calf because the proximal muscles they pull the proximal portion here. Likewise this patient obviously will not be able to perform plant refliction because the most important role of the tendocalcaneus was plant refliction and plant refliction is essential for walking. When we use the push-off phase of our gate when we use our forefoot to push against the ground to propel us forward that gate will be lost so therefore these people will not be able to plant reflux and they will not be able to walk normally. Dorsiflexion will be excessive. Normally we can dorsiflex our foot only up to 20 degrees from the neutral position but in these people dorsiflexion will be very excessive and how will these people walk? These people will develop a unique stance they will laterally or externally rotate their foot to the maximum extent possible by using their gluteus maximus at the hip joint and concomitantly they will extend their hip using the hamstrings and the gluteus and they will extend their knee using their quadriceps and then they will use their midfoot instead of their forefoot to propel themselves forward and that is the stance they will adopt for walking because they cannot plant reflux and therefore they cannot use the push-off phase of the gate which we do without forefoot. So that brings us to the next point how do we repair this ruptured calcaneal tendon? Obviously if we bring the two ruptured ends together and we suture them in a straight line transverse line then this repair is not going to last long or it may rupture again because there will be too much of traction exerted at the suture line. So therefore the ideal way to do it will be what is known as a Z-plast or a Z-plast where a small portion of the distal end of the tendon is removed and a small portion of the proximal portion of the tendon is removed and the two ends are superimposed to each other and they are sutured in the form of a Z and therefore the line of tension is distributed across in a Z fashion that is known as a Z-plasty. And after it has been repaired obviously we have to repair it with using a non-absorbable suture preferably stainless steel and after that we have to carefully repair the paratinon on cover on the cover of the calcaneal tendon and thereafter the patient has to be put on a full cast right from above the knee to the foot why above the knee because if you remember we mentioned that the gastrocnemius muscle takes origin from the lateral femoral condyles and the medial femoral condyles so therefore we have to immobilize the knee joint also and the cast has to be kept in place for at least three months 12 weeks and thereafter the patient will require physiotherapy and rehabilitation for at least another three months and full functional recovery can take up to six months. So that is about the surgical repair of the calcaneal tendon and its post-operative care. Thank you very much for watching ladies and gentlemen I hope you enjoyed the video if you have any questions or comments put them in the comment section below have a nice day.