 There are three ways that we can classify joints based on their mobility. How much movement can you get between two bones? So let's make a note here. We're going to classify them based on mobility. And if you think about it, the mobility of a joint is basically its function. Do you agree with that? So you can have, I mean, I'll tell you right now, you get three choices. You get three degrees of mobility. What are they going to be? Holy movement, very high mobility. Think of a joint that in your brain you're like, oh my gosh, that joint is totally movable. There's like a million of them. Like every joint that you think of probably has a lot of mobility at it. And those joints, if they have a lot of movements possible, those joints are all called diarthrosis. Now just a second, diarthrosis is singular. You can have one. My shoulder is an example of a diarthrosis. I can do all sorts of movements at my shoulder joint. My shoulders are diarthrosis. So if you add an E in there, it's now plural. Let's just go ahead and say that. You might as well throw it in. Okay, so if a great deal of movement is one example of a joint classification, a diarthrosis, and your shoulder is an example of that, then would you agree that very little to know mobility is also a possibility? And these guys are called synarthrosis. So a joint at which not very much motion or movement can happen, that's a synarthrosis. And then of course we have one more category. And it's the in-betweener. This is the one where you actually can have a minimal amount of movement, but it's not basically immobile. So this is a little bit. Let's do small amount of mobility. That is called an amphiarthrosis. Three choices. Diarthrosis, crazed movement. Amphiarthrosis, minimal amount of movement. Synarthrosis, hardly any movement at all. Before, keep those in mind, because now we're going to move into joint structures. We actually have, whoa, three different types of joints that we're going to look at. And we can classify every single joint we look at as either a diarthrosis, an amphiarthrosis, or a synarthrosis. We've already identified that the shoulder is an example of a diarthrosis, just to get our brains kind of working that way. Now we're going to do structural classifications of joints, but we're going to apply a functional label to every single one of them. Doesn't this sound like fun? Let's do it.