 Hi everybody, Dr. O here. Welcome to this short unit on joints. So I'm going to go into a lot more detail later. I'm going to come back through and do an entire video series on kinesiology and probably one on exercise science as well. But for now, we're just going to get into the basics of joints. We're going to cover the joint movements, the basic ways that joints are classified. But for right now, I really just want to talk about the fact that joints are usually a compromise between mobility and stability. A joint can be really stable or really mobile, but it can't be both. That's a sacrifice one for the other. So let me give you an example. Like a really stable joint, like a suture that holds your skull bones together. That is very, very stable, but doesn't move. It's classified as an immovable joint. You're more likely, if you fell on your head, you'd be more likely to break a bone in your skull than you would to dislocate that joint. On the other side, you see like your shoulder. Your shoulder is extremely mobile, but it has to sacrifice a ton of stability in order to do that. In my career working in sports medicine, I can't even keep track of the number of shoulder dislocations that I had to work with. Whereas in the entire time, I only saw three, I believe three hip dislocations. So the hip joint is mobile, but it's a lot less mobile than the shoulder, meaning it's more stable. So the hip joint is so stable that I believe I saw three dislocations and one of them was probably a car accident actually. And to relocate a dislocated shoulder takes just a few pounds of pressure. To relocate a dislocated hip generally takes two or three people and straps in order to relocate the hip. So just keep that in mind. Joints have to either sacrifice stability to be mobile or sacrifice mobility to be stable. So in this unit, we'll talk about joint movements. We'll talk about how we classify those joints. What does it mean to be an immovable joint? We'll talk about what holds joints together as far as fibrous joints versus cartilaginous joints, et cetera. And then we will talk about all the different types of movements you can get from your synovial joints, the joints that you think of. Okay, I think that's plenty for now. Let's dive in and talk about the structural and functional classifications of joints. I hope this helps. Have a wonderful day. Be blessed.