Classification of Joints - Video Tutorials & Practice Problems
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concept
Introduction to Classification of Joints
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In this video, we're going to begin our lesson on the classification of joints. And so joints can actually be classified by both their function and their structure as well. And so it turns out that there are three functional joint classifications and three structural joint classifications for a total of six classifications. And a single joint can be categorized into just one of the three functional joint classifications and just one of the three structural joint classifications. And so a single joint can be classified into two of these groups. And so what this means is that there is overlap between the functional joint classifications and the structural joint classifications. And you can see this overlap really nicely in our map of the less known joints, which we covered in our previous lesson videos. And so if you haven't yet seen that you should go check it out. And so moving forward in our course, we're first going to talk about the functional joint classifications and then in a separate video, we'll talk about the structural joint classifications. And so I'll see you all in our next video.
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Functional Joint Classifications
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In this video, we're going to introduce the functional joint classifications. And so again, there are three functional joint classes that are actually based on the amount of movement that is allowed for by the joint. And so notice down below, we have these three functional joint classes numbered 12 and three. And what you'll notice about each of these functional joint classifications is that they all end with the word arthrosis, which recall from our previous lesson videos is just a term that means joint since recall the root, Arthur or arthro is a root that means joint. Now notice that each of these also ends with the uh letters is which is actually the singular form of these classes. However, if we want to convert them to their plural forms, all we need to do is replace the is with the letters es and so that's how you get the plural forms. Now, the very first functional joint class in our lesson is the sin arthrosis. And so this root sin is a route that means together. And so in a synarthrosis, the skeletal elements in that joint are held so closely together that there's very little space or very little room for movement. And so notice that the s in synarthrosis can remind us that this is going to be a still or stationary joint with basically no movement, especially under normal conditions. And so these synarthrosis are also known as immovable joints. And so notice that for the symbol that we're using for the synarthrosis, that it does not have any kind of movement arrow going around it, unlike the other two symbols for the other two joint classifications. And so because it doesn't have any movement arrows going around it, that can hopefully be a helpful reminder to you that the synarthroses are going to be still or stationary joints with basically no movement. Now, the next functional joint classification in our lesson is going to be the amphiarthrosis. Now, the root amp is actually a root that means both or both sides. And so amphiarthrosis generally allow for movement on both sides of the joint. Now, what you'll notice is that the A in anti arthrosis can remind us that these are joints that are slightly movable joints with just a little or an average amount of movement if you will. And so hopefully the a in a little and the a in average can remind you of the a in anti arthrosis. And so anti arthrosis allow for more movement than synarthrosis which allow for basically no movement. And so notice that the symbol that we're using for anti arthrosis has just one movement arrow going around it. And so hopefully that one movement arrow going around. The symbol for api arthrosis can remind you that amphiarthrosis allow for just a little movement or an average amount of movement. Now, it is also worthy of noting that synarthroses and anti arthrosis are often found in the axial skeleton, but they're not always found in the axial skeleton. It's just often. Now the final functional joint classification in our lesson is the diarthrosis. And so the root die or dia in this word refers to through or across. And so diarthrosis allow for movement through or across the joint. And so the D and diarthrosis can remind us that these joints have dynamic movement or freely and are freely movable joints that allow for a lot of movement, especially with respect to anti arthrosis and synarthrosis. Now, it is also worthy of noting that the amount of movement in these diarthrosis can vary. And so some diarthrosis will have more movement than other diarthrosis. But in general, the diarthrosis allow for more movement than anti arthrosis and anti arthrosis allow for more movement than synarthrosis. And so these diarthrosis are usually going to predominate in the appendicular skeleton. And the diarthrosis are usually the joints that a typical person might think about when they think about a joint. And so it includes joints such as our shoulder joint and our knee joint, for example. And so let's take a look at this image down below where we can start to piece some things together. And so notice over here, we have this person with this skeleton and we are focusing in on specific regions. The first region that we're focusing in on is the skull. And so what you'll notice is that the sutures of the skull, which are highlighted here, essentially these cracks that are in the skull. These are uh a type of joint. And because the these uh essentially sutures in the skull allow for basically no movement. They are still or stationary and allow for no movement. We know that these sutures of the skull that are highlighted here are going to be synarthroses. And again, the root sin is a root that means together. And so notice that the bones of the skull are held so closely together that there's not a lot of room for movement. And uh although again, these are considered uh immovable joints, uh it is important to note that they basically allow for no movement. And so what this means is that the sutures of the skull are designed to accommodate the growth of the brain which is really, really slow. And so the sutures do technically allow for some movement, but it's not really detectable movement that you would think about on a regular basis. And so they're still classified as synarthrosis and uh immovable joints, even though technically, they still allow for like the tiniest, like almost uh unrecognizable amount of movement. Uh But again, the synarthrosis do not allow for as much movement as the anti arthrosis. And so the anti arthrosis again, uh that root ay means both or on both sides. And so usually it allows for movement on both sides of the joint. And uh the a and anti arthrosis can remind us that these joints allow for a little or an average amount of movement. And so they allow for more movement than the s arthrosis. And again, the the one movement arrow going around, the symbol is going to be a helpful reminder that um these anti arthrosis allow for some movement. And so an example here are the intervertebral joints that are in our spine, which allow for some movement allowing us to uh lean forward and also lean backward as well. And so they do allow for movement on both sides of the joint and they only allow for a little movement, not as much as the diarthrosis. And so the diarthrosis, again, the D and diarthrosis can remind us of the D and dynamic movement. And so they allow for dynamic and free movement. And so a classic example of a diarthrosis is going to be the shoulder joint. And so of course, our shoulders allow for a lot of movement through and across the joint. And so uh hopefully, this can help remind you of uh the diarthrosis having a lot of movement and notice that the symbol has multiple movement arrows going around it and because it has multiple movement, arrows going around it, that can hopefully remind you that it has dynamic movement. And so this year concludes our brief lesson on the three functional joint classifications. And moving forward in our course, we're going to continue to utilize these symbols that you see here to represent these three functional joint classifications. And so I'll see you all in our next video.
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example
Classification of Joints Example 1
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So here we have an example problem that says rheumatoid arthritis causes pain when joints move, which joint type is most likely affected. And we've got these four potential answer options down below. Now, the biggest clue that we have here in this problem is that it says rheumatoid arthritis causes pain when joints move. Now, when we're classifying joints based on their movement, that leads us to the functional classes of joints, which recall are the synarthrosis, the anti arthrosis and the diarthrosis, which are all listed here as potential answer options. Now recall that synarthrosis are still or stationary joints that do not move. And so these are also known as immovable joints. And so if we're thinking about joints moving, it's not going to be the synarthrosis. And so for that reason, we can eliminate answer option A and if we can eliminate answer option A, that also means we can eliminate answer option D which says that all three functional joint classes are affected. And so now we're between option B, amphiarthrosis or option C diarthrosis. And again, when we're thinking about movement, it's the diarthrosis that allow for dynamic movement. And so option C is going to be the correct answer for this example, amphiarthrosis recall only allow for a little movement. And so it is true that rheumatoid arthritis is an autoimmune disease that affects diarthrosis or joints that have dynamic movement. And so because that's the case that concludes this example and I'll see you all in our next video.
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Problem
Problem
Which of the following statements is false?
A
All amphiarthroses are in the axial skeleton.
B
All diarthroses allow for a greater range of motion than all amphiarthroses.
C
Synarthroses can allow a small amount of movement.
D
Arthritis is a common disease associated with joints.
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concept
Structural Joint Classifications
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So now that we've covered functional joint classifications in our last lesson video and this video, we're going to introduce the structural joint classifications and talk about how those functional joint classifications overlap with these structural joint classifications. And so there are also three structural joint classes and these structural joint classes are based mainly on the binding material that is used between the skeletal elements to join those skeletal elements together in these joints. Now notice down below, we have listed the three structural joint classes that are numbered 12 and three and so they are the fibrous joints, the cartilaginous joints and the synovial joints. And so in the fibrous joints, as their name implies, the skeletal elements are going to be bound by collagen fibers of dense connective tissue which recalls a type of fibrous connective tissue or a type of connective tissue proper. And the type of dense connective tissue that is usually used in these fibrous joints is dense, irregular connective tissue and we'll be able to see that as we move forward in our course and talk more about these fibrous joints. Now recall from our previous lesson videos that the collagen fibers provide a lot of strength. And so the strength of these collagen fibers makes fibers joints very stable joints. But recall that the stability of a joint comes at the cost of the mobility of the joint. And so fibrous joints have limited mobility. And therefore, they are always going to be classified either as synarthroses or amphiarthrosis, which are types of functional classifications from our previous lesson videos. And that's why we have the symbol for synarthroses and the symbol for amphiarthrosis over here. And so recall that the synarthroses because the symbol does not have a movement arrow going around it. It can remind you that the synarthroses are going to be still or stationary joints that basically allow for no movement and are generally considered immovable joints and amphiarthrosis. Notice the symbol has just one movement arrow going around it which reminds you that they allow for a little or an average amount of movement if you will. And so both synarthrosis and anti arthrosis are going to be limited in their ability uh for mobility or movement, especially in comparison to diarthrosis, which allow for dynamic movement. Now, the second joint classification, structural joint classification in our lesson are the cartilaginous joints. And as their name implies, the bones are going to be bound by cartilage, either hyaline cartilage or fibrocartilage. But elastic cartilage usually does not have a huge role in these cartilages joints. Now, the cartilage in these cartilaginous joints is going to provide stability to the cartilaginous joints. However, once again, the stability of the joint comes at the cost of mobility. And so like the fibrous joints, these cartilaginous joints are always going to be classified either as synarthroses or anti arthrosis, which is why we have the symbols there. Now, the third and final type of structural joint classification in our lesson are the synovial joints and the synovial joints are characterized by having a synovial cavity or a synovial space space in between the bones of the synovial joint and ligaments within an articular capsule. And so later in our course, we're going to talk a lot more about these synovial joints including the synovial cavity, the synovial fluid that they contain and this articular capsule as well. But for now, what you should note is that these synovial joints allow for dynamic movement or free range of movement. And so that means that they are always going to be categorized as diarthrosis, which is why we have the symbol for diarthrosis here in the lesson. And so notice that the symbol for diarthrosis has multiple movement arrows going around it, which reminds us that diarthrosis have a dynamic movement. Now, it is worthy of noting once again that the synovial joints which are categorized as diarthrosis can vary in the amount of movement. And so uh some synovial joints will allow more movement than other synovial joints. But again, we'll get to talk more about this as we move forward in our course. For now, let's take a look at our image down below where we can see a few examples. And so notice over here on the left hand side, we've got the skeleton of this person and we're focusing in on these specific regions. The first region that we're focusing in on is down here on the distal end of the tibia and the fibula of the leg, the lower leg. And so what you'll notice is over here, we have the tibia and here we have the fibula. And what you'll notice is that uh right here in this region on the distal end is a fibrous joint. And we're zooming in here to show you the fibers of this fibrous joint. And again, usually the uh fibers of the fibrous joints are going to be of dense, irregular connective tissue where the fibers are going to have an irregular or random arrangement of fibers in the extracellular matrix as you can see here. And so these fibers joints, again, they provide a lot of stability, but that comes at the cost of mobility. And that's why they're always going to be classified either as synarthroses or anti arthrosis. Now, for the cartilaginous joint, we're focusing in on the spine and so in the spine, there are these intervertebral joints, these in intervertebral discs and in between them are going to be fibrocartilage. And so this is a type of cartilaginous joint. And so notice zooming in here, we can see the image from our previous lesson videos showing cartilage. And so you can see the chondroblast and the choral sites that we talked about from our previous lesson videos on cartilage. And so uh with these cartilaginous joints, again, they provide a lot of stability like the fibrous joints can, however, the stability comes at the cost of mobility. And so like the fibrous joints, they're always classified either as synarthrosis or anti arthrosis. And then last but not least. And this person over here, we're focusing in on the hip joint and in the hip joint, uh that is going to be an example of a synovial joint. And so here you can see the femur is coming into contact with the pelvis here at this joint. And in this joint, what you'll notice is that there is a synovial cavity, which is this space that you can see right here. And it's also going to contain a uh an articular capsule, which is essentially this structure that you can see going around it made of dense irregular connective tissue. And again, we'll be able to talk a lot more about these synovial joints as we move forward in our courts. But the synovial joints are usually going to be the joints that most people will think of when you think about joints. So they include our shoulder joint, which has a lot of dynamic movement, our elbow, our knee, our hip joints for example, and there are many others as well. And so this year concludes our brief lesson on structural joint classifications. And as we move forward in our course, we'll be able to learn a lot more about each of these, uh learn a lot more about each of these types of joints and examples of these types of joints. And we'll also be able to get some practice applying these concepts. So I'll see you all in our next video.
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example
Classification of Joints Example 2
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So here we have an example problem that says, how would you classify a joint that uses cartilage to join bones together and is slightly movable. And we've got these four potential answer options down below. Now, of course, a joint that uses cartilage to join bones together must be a cartilaginous joint. And so that means that we can eliminate answer option A which says fibrous joint and answer option C, which also says fibrous joint. And now we're limited to either option B, cartilaginous synarthrosis or option D cartilaginous anti arthrosis. And so recall that a slightly movable joint is going to have a little movement. And so that also reminds us that it's going to have an average amount of movement if you will. And so the A in a little or the A in average can remind us of the A in amphiarthrosis. And so of course, this slightly movable part tells us that this must be an anti arthrosis. And so notice, option D says cartilaginous anti arthrosis, which is the correct answer. And option B says synarthrosis, but synarthrosis are generally considered immovable. And so for that reason, we can eliminate option B. So that here concludes this example and I'll see you all in our next video.
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Problem
Problem
Which of the following joint classifications is not based on the joint's range of motion?
A
Synovial.
B
Diarthroses.
C
Amphiarthroses.
D
Synarthroses.
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