So when you look at a muscle under a microscope, you can actually see some of these structures. You can see the little striations or those little lines that you see on the slide in front of you. The vertical lines are what makes the myosin heads appear with your naked eye, and of course, the darker circles are the nucleus. So each of the muscles are made up of more than one cell, really. So this is the reason why you cannot really kill off any of your muscle. Don't go crazy and try to severe any of your muscles because they cannot reproduce once you're born. So you got to keep every one of them alive to give you the proper posture, and of course, the way that you want to look. So this slide shows you an overview of all the major muscles that is found in your body. Your glutes is one of them, which is your buttocks muscle. The other one is the inner thigh muscle called the gracilis, and of course the hamstrings which are in, I'm sorry, the back of your leg. Then you have your four muscles that make up the front of your leg, which are called the quadriceps, or what I like to call the drumstick muscles. So you also have the muscles of your arm, like the biceps brachii, and then of course, you have your muscles of your forearm, like the flexors and the extensor groups. So bone. Bone is an interesting kind of tissue. It starts off as cartilage, and when the cartilage is pressured, it will start to form bone evolutionarily. So we have to go back to figure out evolution on how this came about. So if you're thinking about fish, these are the ones that actually started to make the bones really modern. But when you look at the bone structure itself, it is made up of spongy tissue which is mixed cartilaginous tissue, soft bone, with calcified or calcium-embedded bone tissue. When the calcium becomes really enriched and really pressed, this is what we call the compact bone. So when you take a look at any bone structure, the inside of all bone is mostly spongy bone. Only a millimeter, those of you who don't remember what a millimeter looks like, just pull out one of your hair. The thickness of your hair is about a millimeter. Only that is compact bone. That gives this actual strength and structure of a bone. So those of you who are thinking, "How do I get my bones a little bit stronger?", it is all by pressure. So spongy bone will become compact bone when there's more pressure. So therefore, if you don't have good posture, if you're not doing pulling exercises, the muscles will pull against the bone, and therefore, the bones will get stronger and harder. So this is the whole kind of concept when you're doing any kind of exercise. Either you're running, that impact will make the bones get stronger. When you're doing yoga, the muscles will be pulling on and tugging on the bone, and therefore, it will reinforce itself. In order for any of this function to occur, you need calcium. As we talked about before, calcium is very integral to proper bone and muscle health hence the reason why if you do not have enough calcium in your body, the body takes calcium from your bones and gives it to the muscle because of the two types of tissue, which is more important when you're in a fight? When a bear is chasing you? Is good posture better for you or is running away from the bear more important to you? So hence, muscles get precedence over the calcium. So when you lose enough calcium under your bones, you call that disease porous of your bone or osteoporosis. This is the reason why you need to constantly take in a lot of calcium and make sure that the calcium is embedded into this spongy bone so that it makes nice compact bone. So you have your bone structures, and of course, yoga. It's going to keep your vertebrae column perfectly in line. We have a natural curvature of the vertebrae column. It's what we call the S-curvature. So when these curvatures do not go in line, like when you're tilting your neck too much and it fuses, it's called kyphosis or the hunchback syndrome. When your back of your lower back is constantly pushed out a lot, like when you're trying to raise your hump, it's called lordosis. All of these tricks will try to get the muscles to be fully in line with the vertebrae column. So some of these works that you do in yoga, trying to form a artificial kyphotic movement or artificial lordosis movement and holding it there, makes the muscles get stronger which in turn makes the vertebrae column stronger. So as you can see, it's very important for the muscle and their health to be perfect to keep the bones aligned and make sure that the bones become calcified. So all of these things are all attributed by the best movement of nutrients to the right areas. We call that circulation of course. Of course along with that, you need good oxygen levels. So this is what yoga is best at. You are constantly breathing and you're constantly keeping a good posture. Because anytime you have a bad posture, what happens? Your respiratory does not work very well. So everything in physiology is always integrated. You cannot talk about one system over another and say, "What system is better than the other?". They're all integrated, and they make all of the systems more efficient. In the next segment, we'll have Dr. Siensin talk about the joints.
