Hey student Now we are going to focus upon The muscular system. So the muscular System it is basically you know a system Which is present in our body which Help us in the movement and locomotion. So when I say movement it means that any part which are you know the Body which moves. Simply the movement is related but when we talk about the locomotion, It means that a body it moved From one place to the other. So this is how the movement and locomotion they differ. Now when we talk about humans. In humans for the locomotion we have the muscular system then we have the skeletal system. So they both helped us in the movement of our body. So in this now we are going to learn about the muscular system first. Now we when talk about the muscular system we are going to study the muscles. and this study of muscles is termed as, Myology. So this can be called as either myology or sarcology. So the terms sarco is related with the muscles. ok so this is my myology or sarcology. Next we see the muscles they are derived mainly from the mesoderm. so except for the iris and the ciliary body all the body muscles they are derived from the mesoderm where as this iris and the ciliary body they are derived from the endoderm. So now moving forward let’s observe the three types of muscles which are present in our body. So first we will see that these are the Voluntary muscles. These are voluntary muscles. The second types of muscles are called as Involuntary muscles. They are opposite to the voluntary muscles and they are called be involuntary muscles. The third category are the Cardiac muscles so the three types of muscles are voluntary, involuntary and cardiac. Let’s first talk about the voluntary muscles. So when we talk about the voluntary muscles their name is given so because these muscles they are under our control. They work as per our will. hence the name given Voluntary muscles. although they can also be called as Skeletal muscles. it is so because these muscles they are found to be attached to the skeleton of our body. So we can call their skeletal muscles. Also if we observe their structure we see that there are stripes present. Ok, there are various lines present and hence we can also call them as Striated muscles. Because there are striations present. Ok so these two are the other names which can be given for voluntary muscles. Now when we talk about these when we look into their structure we observe something like this so So the structure of striated muscle it looks like this wherein we label we see that the outermost covering of the entire muscle it is called as Epymysium. This is epimysium this is the muscle. Ok inner to which we find that there are groups of myofibrils present meaning the muscle fibers are present. And these groups of muscle fibers are what we called, Fasciculi. So fasciculi are what these are the groups of muscle fibers. Now this group of muscle fiber which is fasciculi it is lined by Perimycium. This is perimycium. Ok now as we have seen that these fasciculi they contain the muscle fibers so I have taken out a muscle fiber and i’m showing you here this is a muscle fiber and the covering of muscle fibers called Endomysium. this is endomysium but the cell membrane of each muscle fiber inner to it if we see There is a cell membrane present and this cell membrane is called as Sarcolemma. Ok the plasma membrane of the muscle fibers or the muscle cells is called as Sarcolemma. So what we have seen we have seen that the Outermost covering is the epimycium then comes in the group of muscle fibers which is the Fasciculi. This is line by the Perimycium. Inner to it when we talk about a single muscle fiber it is appearing like a fiber like this thing. Okay this is covered by endomysium and the cell membrane of the plasma membrane of muscle fiber is called Sarcolemma. Ok now if we see this entire muscle it is again covered by a sheet-like structure Which is called as Fascia. Ok and this fascia forms a structure which attaches this muscle to the bone and this structure is what we call Tendon So tendon and fascia these are these are the structures which help in the attachment. Ok so the fascia it covers this muscle a single muscle and tendon it connects this muscle with the structure which we have seen as the Bone. Ok this is the bone. So this is the structure this is we can see the external structure of the voluntary muscles moving forward will also observe the detailed structure of the skeletal muscle. Now moving forward we will observe that this muscle it can be seen in the limbs. ok Their location is basically limb as I said they found on this skeleton so this is limb and these are under the control of Central nervous system. So this is the CNS. These muscles as in when they work they get quickly Fatigue. So they get tired they get quickly fatigue. Ok Next now we are coming to the second type of muscles which are the involuntary muscles. The involuntary muscles they can also be called as visceral muscles Ok or why so because they are usually found in the visceral organs. Next since they do not possess any striations so we can also call them Unstriated. and as their main name suggests which is involuntary so like I said if the term voluntary means that they are under our will it means that the involuntary muscles they are not under our will. so there are various muscles present in our body which we do not control. They act upon their own because they are controlled by the autonomic nervous system of course they are controlled by the central nervous system as well but the majority of the control is done by the autonomic nervous system. Now if we look at the structure of these they appear pretty smooth so their structure is basically spindle. they appear spindle they contain a single nuclei. the cytoplasm which is present in here is called as sarcoplasm. So this is this now this sarcoplasm it contains various fiber-like structures. So there are various fiber-like structures which are present in the Sarcoplasm. These fiber like structures that we see in here they are called Myofibrils. These are the Myofibrils. So like we had discussed in here there are striations found meaning there are light and dark bands found in the voluntary muscles. These light and dark bands they are absent in case of involuntary muscles. Now coming to their location we see that they are found in the Iris, they are found in the urinary bladder. In fact they are found everywhere all the organs which are not under control such as dermis of skin, and many other places. Ok now as I told you earlier these muscles they are under the control of both the CNS and ANS as well. And these muscles they do not get fatigue because imagine a situation where our body gets fatigue so if my stomach muscle it gets fatigue what would happen will it stop the process of digestion? Will my esophagus stop pushing the food inside? NO. So these muscles they do not get fatigue. This was about the involuntary muscles. Now coming next to the cardiac muscles. the cardiac muscles they are also called as the heart muscles. The cardiac muscles they have a special property. It is that although they are striated muscles but they’re functioning is very much similar to the involuntary muscles. So obviously we cannot control our heartbeat. We cannot control the pumping of heart. So it’s action is involuntary in nature but its structure is more or less similar to the voluntary muscles. So if we see this structure we see that these muscles they are also cylindrical. So they are like I said cylindrical but one main difference that they have as compared to the voluntary muscles, is that these muscles, they are branched in nature. So you see that these are branched they are cylindrical of course but these are branched. Ok so this is the main difference between the voluntary and the cardiac muscle. Next obviously when we talk about their location they are present in the heart. Right they are present in the heart. And next we see that their control is also from CNS as well as from ANS. Ok so when we spoke about the involuntary muscles we saw that they are also controlled by both but most of its control is done by autonomic nervous system that is very minute portion which is controlled by CNS but in here the heart can be controlled by both and these muscles they never get fatigue. They cannot afford to get fatigue basically because the heart can never stop beating untill and unless there is some kind of disorder in them. So this was about the three types of muscles where we have seen the voluntary muscles which are also called as skeletal or striated muscle. This is the basic structure. We have also seen the involuntary muscles which differ from the structure of the voluntary muscles but they are very important for us because they perform most of the auto regulated functions of our body. Lastly the cardiac muscles again they are important and these muscles like I said the voluntary muscles they also have some kind of striations in between them. So you see that there are the light and the dark bands present in here these light and dark bands they are present in the voluntary as well as in the cardiac muscles. So this is the structure-function and location of all the kind of muscles. Moving forward we will observe the detailed structure of the voluntary of the skeleton muscles.