Structural Class: Cartilaginous Joints - Online Tutor, Practice Problems & Exam Prep

Cartilaginous joints, including synchondroses and symphyses, connect bones through cartilage, providing structural stability but limited mobility. Synchondroses, bound by hyaline cartilage, are classified as synarthroses, allowing no movement. In contrast, symphyses, found in the body's midline and composed of fibrocartilage, permit slight movement, classifying them as amphiarthroses. Examples include epiphyseal plates in long bones and intervertebral discs in the spine, which act as shock absorbers, enhancing flexibility and resilience in the skeletal system.

Introduction to Cartilaginous Joints

In this video, we're going to continue to talk about the structural classes of joints by focusing specifically on the cartilaginous joints. And so, in cartilaginous joints, as their name implies, the bones are going to be bound by cartilage. Either hyaline cartilage or fibrocartilage, but not so much elastic cartilage. And so, recall from our previous lesson videos that hyaline cartilage and fibrocartilage are tough yet flexible specialized connective tissues that are able to resist both tension and compression forces. And so, this makes cartilaginous joints structurally stable.

However, recall that the structural stability of a joint comes at the cost of the mobility of the joint. And so, although cartilaginous joints are structurally stable, they are going to have limited movement. And so, like fibrous joints, cartilaginous joints are always going to be classified functionally either as synarthroses or amphiarthroses, which is why we have the symbols for them here. And so again, notice the symbol for synarthroses does not have any movement arrows going around it, which can hopefully be helpful to remind you that synarthroses are still or stationary joints that essentially allow for no movement and are generally classified as immovable joints. And notice that the symbol for amphiarthroses has just one movement arrow going around it.

Which can hopefully help you remember that amphiarthroses allow for just a little or an average amount of movement if you will. Now, really there are 2 types of cartilaginous joints. And they are the synchondroses and the symphases. And so, moving forward in our course, we're going to talk about each of these 2 cartilaginous joints in their own separate videos. Starting with the synchondroses.

So, I'll see you all there.

Synchondrosis (Plural: Synchondroses)

In this video, we're going to talk about the first type of cartilaginous joint in our lesson, which is the synchondrosis. And the plural form is synchondroses. Synchondroses are cartilaginous joints where bones are bound specifically by hyaline cartilage. It's helpful to recall that the root chondro, which is found in the word synchondroses, is a root that means cartilage. Recall from our previous lesson videos on cartilages that hyaline cartilage is a tough yet flexible specialized connective tissue that can resist tension forces.

The hyaline cartilage in these synchondroses makes these joints structurally stable. They provide structural stability. However, recall that structural stability of a joint comes at the cost of the mobility of the joint. Although these synchondroses provide structural stability, they essentially allow no movement. Therefore, they are always classified functionally as synarthroses.

Which is why we have the symbol for synarthrosis here in our lesson. And again, notice that the symbol for synarthrosis does not have any movement arrows going around it. Because it doesn't have any movement arrows going around it, hopefully that can be a helpful reminder that these synarthroses are still or stationary joints that essentially allow for no movement and are generally considered immovable joints. Now, similar to sutures, eventually, some synchondroses bones may actually fuse together to become a synostosis or a bony joint. Recall that the root ost is a root that means bone, and so hopefully that can remind you that a synostosis is when two or more bones fuse together into a single bone.

The hyaline cartilage in these synchondroses can eventually ossify. And, of course, that means that it can be replaced by new bone tissue. Not all synchondroses are going to ossify to become a synostosis. Only some of them will, and usually the ones that are involved with growth and development are going to turn into synostoses, such as the epiphyseal plates, which we'll get to see down below in our image.

Notice here, in the middle of the image we have this human skeleton and we're focusing on very specific regions. On the left hand side, we're focusing on the femur. You can see here is the femur. Notice that we're zooming into the top portion here of the femur. What you'll notice is that these blue lines that you can see here and here, where we're indicating with these arrows, these are the epiphyseal plates.

Also, sometimes referred to as growth plates. These are synchondroses; there is hyaline cartilage that is connecting bones. It is connecting the epiphysis of the bone to the diaphysis of the bone. These epiphyseal plates can be found in long bones, such as the femur, the humerus, and the tibia, for example.

These epiphyseal plates, again, in children and adolescents, they will be present. But, when they reach adulthood, these epiphyseal plates are going to ossify, and the bones will fuse together to create synostosis. Now, notice over here on the right side, we're focusing on another example of synchondrosis, which is between the first rib and the sternum, specifically the manubrium of the sternum or the superficial portion of the sternum. Notice, here we have the first rib and the first rib is being connected to the manubrium of the sternum or the superficial portion of the sternum by the hyaline cartilage that you can see here. This is a synchondrosis.

It is only the first rib, that is the junction that connects the first rib to the sternum that is considered a synchondrosis. Many of the other ribs that lie beneath are going to have junctions that are considered synovial joints. We'll get to talk more about those later in our course. But for now, this concludes our brief lesson on synchondroses, and we'll be able to get some practice applying these concepts and learn about the other type of cartilaginous joint as we move forward in our course. So, I'll see you all in our next video.

Structural Class: Cartilaginous Joints Example 1

So here we have an example problem that asks, how are synchondroses similar to sutures? And we've got these 4 potential answer options down below. Now, option a says that they are both made of rigid hyaline cartilage. But of course, we know that this is not true for sutures because recall that sutures are a type of fibrous joint, where the bones of the skull are connected by dense irregular connective tissue. Not connected by hyaline cartilage.

So for that reason, we can eliminate answer option a. Now option b says that the epiphyseal plates and sutures can both ossify over time to form synostoses, and recall that the epiphyseal plates are examples of synchondroses. And so, recall from our previous lesson videos that this is actually true. The hyaline cartilage and epiphyseal plates can ossify over time to formsynostoses. the sutures of the skull can also ossify over time to form synostoses. And so, because option b is true, we can go ahead and highlight it as the correct answer option.

Recalling that ossification just means the replacement or the formation of new bone tissue. And, synostoses recall are just when 2 bones fuse together into a single bone. Now, let's check option c and d just to be sure. Option c says that the costosternal synchondrosis and sutures both allow a small amount of movement, but recall that joints that allow for a little or an average amount of movement with a slight amount of movement are categorized as amphiarthroses. But, recall that synchondroses and sutures are both classified as synarthroses, meaning that they are still or stationary, and generally considered immovable joints.

And so, option c is not going to be the best option for this example. Now, option d says that they are both fibrous joints, but of course, we know that this is not true. We know that the sutures are considered fibrous joints. However, the synchondroses with that root chondro, that means cartilage, it is going to be a cartilaginous joint, not a fibrous joint. And so that's why we can eliminate option d.

And so this here concludes this example problem, and I'll see you all in our

Which of the following statements is true?

• A. Synchondroses can be either synarthroses or amphiarthroses.
• B. Synchondroses are more functionally similar to syndesmoses than gomphoses.
• C. Synchondroses can be found in both the axial and appendicular skeleton.
• D. All statements are true.

Symphysis (Plural: Symphyses)

In this video, we're going to talk about the second type of cartilaginous joint in our lesson, which is the symphysis. And the plural form is symphyses. What's important to notice about the symphysis is that they have a unique spelling that we can actually use to our advantage to help us remember important features about these symphyses. Unlike many of the other joints that we've talked about in our previous lesson videos that start with the letters s y n as in Nancy, the symphyses start with the letters s y m as in Mary. And that m is quite unique to these symphyses, for that reason.

We can utilize this letter m in symphyses to help us remember key features about these symphyses. Also, what you'll notice is also unique about the symphyses is not just the letter m, but also the letters p h. That p h phonetically makes an f sound. Together the m and the p h can help us remember critical features about these symphyses. This is why we have those letters underlined here underneath of symphyses.

Symphyses are cartilaginous joints in the body's midline. They're found always in the center or the midline of our body. That is where the m in symphysis can help us, with remembering that these symphyses are found in the body's midline. Now, they're found in the body's midline where bones are going to be bound specifically by fibrocartilage. And so, the p h in symphysis, which phonetically makes an f sound, can remind us of the f in fibrocartilage.

Hopefully, by utilizing these memory tools, you can easily remember the most important features of these symphyses. Recall from our previous lesson videos that fibrocartilage is designed for strength and flexibility. The fibrocartilage found in these symphyses actually does allow for a little movement. Because it does allow for a little movement, they are always going to be functionally classified as amphiarthroses, which is why we have the symbol for amphiarthroses here. Notice that the symbol for amphiarthrosis has just one single movement arrow going around it.

Which can hopefully help you remember that these amphiarthrosis allow for just a little or an average amount of movement, if you will. Recall from our previous lesson videos on cartilages that fibrocartilage is very compressible, resilient, and flexible. Because that's the case, this allows symphyses to act as shock absorbers. That will be very important to their functions. Let's take a look at our image down below where we can see a few examples of these symphyses.

Here we have our human skeleton and we're focusing on specific regions. On the left-hand side, we're focusing on the spine of this human skeleton. The intervertebral joints that are found in the spine are actually going to be these symphyses. Again, the spine is found in the midline of our body. Of course, the symphysis is going to contain fibrocartilage connecting the bones.

What you can see in blue, this is going to represent the fibrocartilage. And again, it is extremely compressible, resilient, and flexible allowing it to act as a shock absorber. Which is really important for our spine to be able to do since it's constantly having to fight against gravity. It's constantly being compressed and it needs to be able to absorb shock. Recall that amphiarthroses, the root amphi is a root that means both, or both sides.

Amphiarthroses allow for a movement on both sides of the joint. This allows this synthesis to have movement on both sides. This allows us to be able to lean backwards and also lean forwards. Collectively, these symphyses are amphiarthrosis and so they allow for a little movement. But collectively, all of the intervertebral joints that allow for a little movement can build up and stack up allowing our spine to have a pretty decent amount of movement.

But, the individual joint is an amphiarthrosis. Now, on the right side of the image, we're focusing here on the pelvis and what you'll notice is that here, right in the midline again, we have what's known as the pubic symphysis. The pubic symphysis is found here in the pelvis, and so it is connecting the bones on both sides and it will allow for movement on both sides of the joint. Again, it's made up of fibrocartilage, so it is extremely resilient and compressible and can act as a shock absorber for movements in our body. This here concludes our brief lesson on symphyses, and we'll be able to get some practice applying these concepts and learn more about other joints as we move forward in our course.

So, I'll see you all in our next video.

Structural Class: Cartilaginous Joints Example 2

So here we have an example problem that asks which type of joint would be best suited to withstanding a great deal of mechanical stress, while also being compressible in order to absorb shock. And we've got these 4 potential answer options down below that include synchondroses, syndesmoses, symphyses, and gomphoses. And so, of course, recall from our previous lesson video that symphyses are going to contain fibrocartilage, and you can think that the "ph" noise phonetically can remind you of the "f" noise in fibrocartilage. And so, recall that the fibrocartilage is going to allow for a great deal of mechanical stress withstanding, while also being compressible in order to absorb shock. And so the correct answer to this problem is answer option C, symphyses.

Now synchondroses are going to be cartilaginous joints made of hyaline cartilage, but the hyaline cartilage does not allow for shock absorption like fibrocartilage does. And so, for that reason, we can eliminate answer option A. Now, syndesmoses and gomphoses are both types of fibrous joints that utilize fibrous connective tissue, mainly dense irregular connective tissue, which allows for a lot of strength. However, it does not have the shock absorbing properties that fibrocartilage has. And so for that reason, we could have eliminated answer options B and D.

And so again, option C, symphyses, is the correct answer to this example. I'll see you all in our next video.

Which joint type is primarily responsible for allowing growth in long bones during childhood?

• A. Syndesmosis
• B. Synchondrosis
• C. Symphysis.
• D. Gomphosis.

Which of the following describes a cartilaginous joint?

• A. The amphiarthrosis between the radius and ulna, allowing for forearm rotation.
• B. The freely movable shoulder joint, which contains articular and hyaline cartilage.
• C. The synarthrosis between bones of the skull.
• D. The amphiarthrosis between adjacent vertebrae in the spine.

Here’s what students ask on this topic:

What are the two types of cartilaginous joints?

The two types of cartilaginous joints are synchondroses and symphyses. Synchondroses are joints where bones are bound by hyaline cartilage, providing structural stability but allowing no movement, classifying them as synarthroses. Examples include the epiphyseal plates in long bones like the femur and humerus. Symphyses, on the other hand, are found in the body's midline and are composed of fibrocartilage. They allow for slight movement, classifying them as amphiarthroses. Examples include the intervertebral discs in the spine and the pubic symphysis in the pelvis. Both types of joints provide structural stability but differ in their mobility and specific locations in the body.

What is the functional classification of synchondroses?

Synchondroses are functionally classified as synarthroses. This means they are immovable joints that allow for no movement. The bones in synchondroses are bound by hyaline cartilage, which provides structural stability but limits mobility. Examples of synchondroses include the epiphyseal plates in long bones, which eventually ossify and fuse the bones together, and the junction between the first rib and the manubrium of the sternum. The lack of movement in these joints is crucial for maintaining the structural integrity of the skeletal system during growth and development.

What is the role of fibrocartilage in symphyses?

Fibrocartilage in symphyses plays a crucial role in providing both strength and flexibility. It is highly compressible, resilient, and acts as a shock absorber, which is essential for joints that experience constant pressure and movement. For example, the intervertebral discs in the spine are symphyses composed of fibrocartilage, allowing for slight movement and absorbing shocks to protect the spinal column. Similarly, the pubic symphysis in the pelvis, also made of fibrocartilage, provides stability while allowing for slight movement, which is important for activities such as walking and childbirth.

How do synchondroses and symphyses differ in terms of mobility?

Synchondroses and symphyses differ significantly in terms of mobility. Synchondroses are classified as synarthroses, meaning they are immovable joints that allow for no movement. The bones in synchondroses are bound by hyaline cartilage, providing structural stability but limiting mobility. Examples include the epiphyseal plates in long bones. In contrast, symphyses are classified as amphiarthroses, allowing for slight movement. These joints are found in the body's midline and are composed of fibrocartilage, which provides flexibility and acts as a shock absorber. Examples include the intervertebral discs in the spine and the pubic symphysis in the pelvis.

What are some examples of synchondroses in the human body?

Examples of synchondroses in the human body include the epiphyseal plates (growth plates) found in long bones such as the femur, humerus, and tibia. These plates are composed of hyaline cartilage and connect the epiphysis (end) of the bone to the diaphysis (shaft) during growth and development. Another example is the junction between the first rib and the manubrium of the sternum. This connection is also made of hyaline cartilage and provides structural stability while allowing no movement, classifying it as a synarthrosis. These synchondroses eventually ossify and fuse the bones together as growth ceases.