 To understand the gross function of muscle organs, you really need to have at least a acceptance of, okay, I accept how the cell itself is functioning. What I want to tell you is that I'm going to show you a brief video that is physio. And we're going to watch like 10 seconds of the video. I'm not going to watch the whole thing because it goes into crazy details that you don't need to know. I just want you to be able to visualize this to, number one, have some cellular anatomy that will help you understand physio when you take it, whenever you take it. But number two, so that you can have a mechanism in your mind so you can accept that how muscle tissue is going to shorten what the mechanism is that actually enables the tissue to shorten. Remember that we're dealing with sarcomeres, which are the repeating units of myofilaments that are just organized in bundles to make up the myofibril. This video starts us off looking at a single muscle cell. And you could, I don't know what those green things are, maybe those are nuclei that are bust and loose because you know, nuclei, I always want to bust loose, but this thing right here is a single skeletal muscle cell. And if we, she's talking and I just muted her, but skeletal muscle cells do a lot of things for us. They enable us to move. Now, we zoomed in. We zoomed in to the massive amounts of protein myofibrils. And now we've got myofilaments. And look, the pink here are the thick filaments of myosin and the thin ones are the thin filaments. The blue ones are the thin filaments. And you can actually see this Z line is a structure. You can't see the M line as well here, but here are two pieces of thick filament that are attached to each other. And you can, it gives you the sense of depth, like that whole thing is a bundle, like a bundle of spaghetti noodles. And then if you looked at that from far away, you can totally see the striations, can't see you. And so I made, I couldn't help it, a bundle of spaghetti noodles that I drew all over. Can you see my striations on my bundle? Here was my original spaghetti noodle. This is a myofibril made up of all my thick and thin filaments, just like you can see there on that video. But then if you bundle them together and stick this whole thing inside of a single muscle cell, can you visualize how, yeah, that whole thing gives you like this striated, stripy look. Just for perspective, I've got, of course, a little bag. What do you think the bag represents if I stick all the myofibrils inside a bag? Well, we could definitely have it be the cell membrane and we could throw in some nuclei along the edges, M&Ms. And then we could actually build a model of a muscle cell. We could also then put it in another bag and then we would have the endomyceum surrounding our muscle individual myofiber or individual cell. Okay, so you're comfortable with this. You're comfortable that what we're looking at is actually that, my little bundle madness. There we go, with our stripes. Okay, remember how I told you the little thick filaments had these little funny heads? You aren't going to believe how cool this is. There are their little heads and those heads actually contract. There they go, holy what? Yeah, just like that. Now, look, oh, how cool is that? Can you see how the whole thing shortens? Okay, this is where it gets into all the craziness of physiology. We got to have different kinds of things and ions and all sorts of stuff and it's really hard for me not to continue on and explain that because it's really fun. All right, but we're going to stop there. Now, you have a visual for how muscle tissue shortens. You have a visual for how muscle organs attach to bones to cause overall actions. Now, we're going to look at some required muscles that we're going to explore in lab. I don't know, there's like 600 muscles in your entire body. We are not going to look at 600. I think we have 74 on our list. Is that all? That's all, but at least we get to cover them over three laps. I'll be right back to talk about our gross anatomy of muscles in your face.