Classification of Joints - Online Tutor, Practice Problems & Exam Prep

Introduction to Classification of Joints

In this video, we're going to begin our lesson on the classification of joints. Joints can actually be classified by both their function and their structure as well. It turns out that there are 3 functional joint classifications and 3 structural joint classifications, for a total of 6 classifications. A single joint can be categorized into just one of the 3 functional joint classifications and just one of the 3 structural joint classifications, meaning a single joint can be classified into 2 of these groups. What this means is that there is overlap between the functional joint classifications and the structural joint classifications. You can see this overlap really nicely in our map of the lesson on joints which we covered in our previous lesson videos. If you haven't yet seen that, you should go check it out. Moving forward in our course, we're first going to talk about the functional joint classifications. Then, in a separate video, we'll talk about the structural joint classifications. I'll see you all in our next video.

Functional Joint Classifications

In this video, we're going to introduce the functional joint classifications. And so again, there are 3 functional joint classes that are actually based on the amount of movement that is allowed by the joint. And so notice down below, we have these 3 functional joint classes numbered 1, 2,3. 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 letters I S 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 I S with the letters E S. And so, that's how you get the plural forms. Now, the very first functional joint class in our lesson is the synarthrosis. And so, this root syn is a root 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 synarthroses 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 amphi 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 amphiarthrosis 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 amphiarthrosis. And so, amphiarthrosis allow for more movement than synarthrosis which allows for basically no movement. And so, notice that the symbol that we're using for amphiarthrosis has just one movement arrow going around it. And so hopefully that one movement arrow going around the symbol for amphiarthrosis 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 amphiarthroses 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 di or dia in this word refers to through or across. And so, diarthroses allow for movement through or across the joint. And so, the D in 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 amphiarthroses and synarthroses. Now, it is also worthy of noting that the amount of movement in these diarthroses can vary. And so, some diarthroses will have more movement than other diarthroses. But in general, the diarthroses allow for more movement than amphiarthroses and amphiarthroses allow for more movement than synarthroses. And so, these diarthroses are usually going to predominate in the appendicular skeleton. And the diarthroses are usually the joints that a typical person might think about when they think about a joint, and s

Classification of Joints Example 1

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 4 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 synarthroses, the amphiarthroses, and the diarthroses, which are all listed here as potential answer options. Now, recall that synarthroses 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 synarthroses. 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 3 functional joint classes are affected. And, so now, we're between option B, amphiarthroses, or option C, diarthroses. And again, when we're thinking about movement, it's the diarthroses that allow for dynamic movement. And so, option C is going to be the correct answer for this example. Amphiarthroses recall only allow for a little movement. And so, it is true that rheumatoid arthritis is an autoimmune disease that affects diarthroses, 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.

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.

Structural Joint Classifications

So, now that we've covered functional joint classifications in our last lesson video, in 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 3 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 3 structural joint classes that are numbered 1, 2, 3. 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 amphiarthroses. 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 amphiarthroses 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, amphiarthroses, 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 synarthroses and amphiarthroses are going to be limited in their ability, for mobility or movement. Especially in comparison to diarthroses, 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 cartilaginous 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 amphiarthroses. Which is why we have the symbols there. Now, the 3rd 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 diarthroses which is why we have the symbol for diarthroses here in the lesson. And so, notice that the symbol for diarthroses has multiple movement arrows going around it which reminds us that diarthroses have, dynamic movement. Now, it is worthy of noting once again that the synovial joints, which are categorized as diarthroses, can vary in the amoun

Classification of Joints Example 2

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? We've got these 4 potential answer options down below. Now, of course, a joint that uses cartilage to join bones together must be a cartilaginous joint. Therefore, we can eliminate answer option A, which says fibrous joint, and answer option C, which also says fibrous joint. Now we're limited to either option B, cartilaginous synarthrosis, or option D, cartilaginous amphiarthrosis.

Recall that a slightly movable joint is going to have a little movement. This also reminds us that it's going to have an average amount of movement, if you will. The 'a' in 'a little' or the 'a' in 'average' can remind us of the 'a' in amphiarthrosis. And so, this slightly movable part tells us that this must be an amphiarthrosis. Notice option D says, cartilaginous amphiarthrosis, which is the correct answer. Option B says synarthrosis, but synarthroses are generally considered immovable. For that reason, we can eliminate option B. This here concludes this example, and I'll see you all in our next video.

Which of the following joint classifications is not based on the joint's range of motion?

• A. Synovial.
• B. Diarthroses.
• C. Amphiarthroses.
• D. Synarthroses.