Structural Class: Fibrous Joints - Video Tutorials & Practice Problems
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1
concept
Introduction to Fibrous Joints
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2m
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In this video, we're going to talk about the first structural class of joint in our lesson, which are the fibrous joints. And so in fibrous joints, as their name implies, the skeletal elements are going to be bound by collagen fibers of dense connective tissue, which recall is a type of fibrous connective tissue or a type of connective tissue proper. Now, the exact type of dense connective tissue that's used in these fibrous joints depends on the specific type of joint and its function. However, it's very often the case that dense irregular connective tissue is used in these fibrous joints. And we'll be able to see that as we move forward in our course and talk more about these fibrous joints. Now recall that collagen fibers provide a lot of strength and the strength of these collagen fibers really makes these fibers joints structurally stable. But recall that the stability of a joint comes at the cost of the mobility of the joint. And so these fibers joints, although structurally stable are going to have limited movement and because they have limited movement, this means that the fibrous joints are always going to be classified either as synarthroses, which recall are still or stationary joints that essentially allow for no movement and are generally classified as immovable joints or the fibrous joints could be classified as amphiarthrosis which recall allow for a little movement or an average amount of movement. And so this is why we have the symbols for synarthrosis and amphiarthrosis here and again, the symbol for synarthrosis does not have that movement arrow going around it, which means that it allows for essentially no movement. Whereas the amphiarthrosis symbol has one movement arrow going around it, which can remind you that it allows for just a little movement or an average amount of movement. Now, there are actually three types of fibrous joints and they are sutures, gooses and sends moses and moving forward. In our course, we're going to talk about each of these three types of fibrous joints in their own separate videos starting with the sutures.
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concept
Sutures
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7m
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In this video, we're going to talk about the first type of fibrous joint in our lesson, which are the sutures and so sutures are fibrous joints of dense irregular connective tissue, which recalls a type of fibrous connective tissue or connective tissue proper. And these sutures are found only joining the bones of the skull and so sutures are only found in the skull. Now recall that dense irregular connective tissue is characterized by having these really densely packed protein fibers in the extracellular matrix with an irregular or random arrangement that actually allows it to resist forces in multiple directions, which is really important for the skull to be able to do in order to protect our brains. Now recall that dense irregular connective tissue has lots of collagen protein fibers. And those collagen protein fibers provide a lot of strength and the strength of those collagen protein fibers allows the sutures to provide a lot of structural stability and support to the skull. And so again, that's really important for the skull to have in order to protect our brains effectively. However, recall that the structural stability of a joint comes at the cost of mobility of the joint. And so a suture provides structural stability to the skull, but it essentially allows for no movement. And therefore, these sutures are always going to be classified functionally as synarthroses, which is why we have the symbol for synarthroses here. Now again, notice that the symbol for synarthrosis does not have any movement arrows going around it, which can remind us that these synarthroses are going to be still or stationary joints that essentially allow for no movement and are generally considered immovable joints. Now, many of the sutures of the skull actually have wavy, irregular interlocking edges and those wavy irregular interlocking edges can add a lot of strength to the skull, which can help to prevent fracturing of the bones of the skull, which again is very important to protect the brain. Now, although sutures are always classified as synarthroses, uh it is important to note that sutures are actually designed to allow for skull expansion as the brain grows during youth. And so of course, brain growth during youth is going to be a very slow process. And so the movement of the sutures during youth is also very, very slow. And therefore, even though there is technically small, small amounts of movement, they are still classified as synarthrosis because generally, we don't really detect that movement uh on a regular basis, uh or it's hard to detect that movement on a regular basis. Now, it's also important to note that the dense irregular connective tissue of a suture will actually ossify over time, meaning that it forms bone or is replaced with new bone tissue. And again, this happens over time in adults. Now, the specific timing of the closure of a suture and the ossification of a suture will actually vary among individuals because it's influenced by many different factors, including genetic factors and your overall health. However, usually by middle age of adults, uh the sutures of the skull or most of the sutures of the skull have ossified. Now, the ossification of the sutures in the skull actually fuses the suture bones into a single bone forming what is known as a sin ossis or a bony joint. And so the root in sin ossis is a root that means bone. And so again, the dense irregular connective tissue of the sutures will be replaced with bone over time. And this is a natural process. And uh once those uh bones have completely fused together to form a synostosis or a bony joint, then of course, there will be no movement and it will be also a synarthrosis. And so let's take a look at our image down below where we can start to piece together some of these ideas. And notice on the left hand side of the image we're focusing in on the future of a younger skull. And so what you'll notice is that uh the sutures here of the skull are you can see, are these essentially these cracks that you can see uh highlighted here in the skull. And if we zoom in uh what you'll notice is that the edges of the sutures are wavy and irregular uh and interlocking edges that provide a lot of strength and can help to prevent fracturing of the skull. And what you'll notice is that zooming into the suture, that the bones of the skull, this side of the bone and this side of the bone are being held together by the dense irregular connective tissue. Uh And so this is why these sutures are classified as fibrous joints. Since dense irregular connective tissue is a type of fibrous connective tissue. Now again, this is the suture of a younger skull. There is uh a very small separation of the bones of the skull, especially early on. But over time, the bones of the skull will actually ossify and fuse together to form a synostosis. And so notice the right side of our image is actually showing and focusing in on the synostosis of an older skull. And so what you'll notice is that the sutures have fused and the bones of the skull have fused together to form these synostosis or bony joints. And zooming in, you can still see the irregular wavy uh interlocking edges. But notice that the bones have fused together completely. And again, that is going to help uh prevent uh fracturing and also help protect the uh the brain even better over time. And so over here, what we can say is that the dense irregular connective tissue of the suture ossified to form bone. And so this year concludes our brief lesson on sutures. And we'll be able to get some practice applying these concepts and talk about other types of fibrous joints as we move forward in our course. So I'll see you all in our next video.
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example
Structural Class: Fibrous Joints Example 1
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So here we have an example problem that says use the words in the word bank to fill in the blanks and complete the sentences that you can see down below right here. And so notice that we've got the word bank highlighted here and the words are ossify and movable, skull and protect. And so the first sentence here says that sutures allow for the blank to expand in youth. And so of course, this first blank here must be the word skull. And so it's true that sutures allow for the skull to expand in youth. And since we've used skull here for this first blank, we can go ahead and cross it off the list in the word bank. Now continuing the sentence here, it says sutures allow for the skull to expand in youth as they do not completely blank and fuse cranial bones together until brain development and growth are completely finished. Now, of course, the second blank here is going to be the term ossify, which means to form new bone tissue. And so it is true that the sutures do not completely ossify until brain development and growth are completely finished. And so because we've used ossify here, we can cross it off the list in the word bank above. Now, the next sentence says that their primary function is to blank the brain. Now, of course, the primary function of the skull is to protect the brain. And of course, the sutures which are a part of the skull are also going to help protect the brain. And so this next blank here is going to be the word protect. And so we can go ahead and cross off, protect from the list above. And then the last sentence says that they are able to do this because they are not because they are completely blank joints. And of course, the last term is immovable. And so recall that these sutures are going to be synarthroses, which means that they are considered immovable joints. So they do not allow for movement. And so uh recall that there is an inverse relationship between the mobility of a joint and the stability of the joint. And so because these sutures allow for no movement, they are immovable joints, this means that they allow for a great deal of stability and support and that's exactly what the skull needs in order to protect our brain. And so this here concludes this example and I'll see you all in our next video.
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Problem
Problem
Imagine you're a doctor, and a middle-aged patient comes to you with a medical condition that is causing their collagen fibers to become weak. What affect would this have on the sutures in their skull?
A
Sutures are made of short collagen fibers, so their sutures would loosen and become fragile.
B
There is never fibrous connective tissue in sutures so it wouldn't have an effect.
C
At this patient's age their sutures will have ossified; therefore, this condition won't affect their sutures.
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Problem
Problem
In a baby, the bones of the skull are joined by fibrous connective tissue. Over time, these bones fuse together to form ossified immovable joints. How would you classify these joints?
A
Amphiarthroses in a young skull, synarthroses in an older skull.
B
Fibrous joints in a young skull, synostoses in an older skull.
C
Cartilaginous joints in a young skull, synostoses in an older skull.
D
Fibrous joints throughout life.
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Problem
Problem
Which of the following scenarios is most concerning for a pediatric patient?
A
The epiphyseal plate in their femur is not fully ossified.
B
Their sutures are ossified.
C
Their sutures are not fully closed.
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concept
Gomphosis (Pleural: Gomphoses)
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In this video, we're going to talk about the second type of fibrous joint in our lesson, which is the gump osis and the plural form are the gums. And so gums are fibrous joints found only bolting teeth to their bony sockets in our gums. In fact, the root gum which is found in the term gums is a root that means bolt. And so you can think these gums are found in our gums. Now, it is important to recall from our previous lesson videos that teeth are technically not considered bones since they have a different structure and composition than bones. And so these compos are unique in that they are not connecting bone to bone, but instead they are connecting bone to teeth. Now because these gumbos are bolting the teeth to their bony sockets in our gums. These gumbos are going to be structurally stable joints since they again anchor our teeth to our jawbone, either the maxilla or the mandible. But recall that structural stability of a joint comes at the cost of mobility of the joint. And so, although these gooses are structurally stable, anchoring the teeth to the jawbone, they essentially allow for no movement under usual conditions except under the chewing forces or mastication forces. And so the gumbos are designed to allow our teeth to move very, very subtly when we are chewing, in order to help transfer chewing forces from our teeth to our jawbone to help alleviate the pressure on our teeth and prevent our teeth from shattering when we bite into something hard. However, that movement is very, very subtle and only really occurs under chewing types of forces. Uh but generally, these gooses allow for essentially no movement. And because that's the case gooses are always going to be functionally classified as synarthroses, which is why we have the symbol for synarthroses right here. And so again, notice that the symbol for synarthrosis does not have any movement, arrows going around it, which can be helpful to remind you that these synarthroses are still or stationary joints that essentially allow for no movement and are generally considered immovable joints. Now, the paradental ligament is also very important to the gums. And so it's the paradental ligament that actually makes the gum phos a fibrous joint. And this is because the parad ligament is dense, irregular connective tissue that essentially glues our teeth firmly into their bony sockets. And so the root perry and paradental is a root that means around and the root oont or dat is a root that means tooth. And so these parad ligaments are found around our teeth. Now, what's important to note is that uh recall that dense irregular connective tissue is characterized by having really densely packed protein fibers in the extracellular matrix with an irregular or random protein fiber arrangement, which allows it to resist forces in multiple directions. And so, when we are chewing, it is important for the poses to uh resist forces in multiple directions. And so uh many of the classic ligaments in our body usually are going to be made of dense regular connective tissue with parallel fiber arrangement because they usually only need to resist forces in one direction. But these paradental ligaments, they need to be able to resist forces in multiple directions, which is why it's important. They have dense irregular connective tissue. Now, it's also worthy of noting that in youth, the paradental ligament actually deteriorates to allow our deciduous teeth or our baby teeth to fall out. And then eventually those baby teeth are replaced with larger teeth that are more suitable for chewing and eating. And so let's take a look down below at our image where we can start to piece things together. So notice over here, we have this guy and you can see his skeleton over here and zooming in, you can actually see the gums, you can see the tooth is right here in this position. And then you can see that the jawbone, the mandible is down below in this region. And so the tooth is being anchored to the jawbone uh in this gums. And what you'll also notice is that there are these little tiny paradental ligaments that are all throughout here, essentially connecting the tooth to the bone and uh essentially acting like glue. And so what you'll notice is that over here on the right, we have this analogy for the gomphosis. And so what you'll see is that we have some uh bolt, which we called the root gum is a root that means bolt. We have a bolt being bolted into some wood. And so here in this analogy, the wood would represent the jawbone and the bolt itself would be the tooth. And so the tooth is going to be the bolt. And then what you'll notice is that over here, this person clearly did not have a lot of carpentry knowledge, but they use glue in addition to the bolt in the wood. And so the glue that you see is really going to be the paradental ligament. And again, the root harry is a root that means around and perry Odon ligament. Uh The root oont is a root that means uh tooth. And so these paradental ligaments are found all around the teeth, essentially gluing the teeth firmly to their bony socket. And so these gooses are found in your gums. And so that can be another helpful reminder. And so this here concludes our brief lesson on the gums or the guo and we'll be able to get some practice applying these concepts and learn more about other types of fibrous joints as we move forward in our course. So I'll see you all in our next video.
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example
Structural Class: Fibrous Joints Example 2
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2m
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So here we have an example problem that asks which of the following statements about the development of sutures and guo is true. And we've got these four potential answer options down below. Now, option A says that they both start off rigid at birth and remain that way throughout life. Now, of course, we know that this is not going to be true, especially if sutures, recall that the sutures of a young skull actually have bones that are more separated and over time, those su sutures are going to develop into synostosis where ossification of the dense irregular connective tissue occurs and that tissue is replaced with bone tissue to allow the bones of the skull to fuse together over time. And so they don't start off rigid, they actually become more rigid over time. And so for that reason, we can eliminate answer option A because it's not the best answer option. Now, option B says they both start off less developed at birth and continuously become more rigid throughout life. Now, this is going to be true of sutures but recall that with gums that at some point during youth, the gumbos actually completely deteriorate, which allows the baby teeth to fall out. And so they won't continuously become more rigid because at some point, they must deteriorate and become less rigid. And so option B is not going to be the best answer. Now, notice option C says gomphosis, unlike sutures break down completely during youth to allow shedding of baby teeth. And this is going to be the correct answer to this example problem so we can go ahead and highlight it and mark it as the correct answer. Now, option D says that sutures unlike gooses become weak and unstable in old age, but this is not going to be true. Recall that sutures will actually develop into synostosis where the bones of the skull actually fuse together and that dense irregular connective tissue is replaced with a tissue or bone tissue. And so that actually makes the uh sutures become stronger in older age. And so uh option D is not going to be the best answer. And so uh again, option C is the correct answer to this example. And so I'll see you all in our next video.
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Problem
Problem
In gomphoses, bones are connected to teeth via which of the following structures?
A
Tendons.
B
Periodontal ligament.
C
Loose connective tissue.
D
Osseus membrane.
10
concept
Syndesmosis (Pleural: Syndesmoses)
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4m
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In this video, we're going to talk about the third type of fibrous joint in our lesson, which is the syndesmosis in the plural form are the syndesmosis. And so these Sindiso are fibrous joints, connecting bones via these bundles or ligaments that are made of dense irregular connective tissue, which recalls the type of fibrous connective tissue that is characterized by these really densely packed protein fibers in the extracellular matrix with an irregular or a random protein fiber arrangement which allows them to resist forces in multiple directions. Now, the greater bone separation and the longer fibers of these sends moses actually allows for more mobility than the other two types of fibrous joints, the sutures and the gums. And so recall from our previous lesson videos that whereas the sutures and gumbos were both classified as sin arthrosis since they were still or stationary joints that essentially allowed for no movement and are generally considered immovable joints. Whereas the sendo moses because of their greater bone separation and longer fibers allowing for more mobility, they are always going to be classified as amphiarthrosis, which is why we have the symbol for anti arthrosis here. And so recall from our previous lesson videos that amphiarthrosis allow for a little movement or an average amount of movement if you will. And so notice that the symbol for anti arthrosis has one movement arrow going around it, which can hopefully help remind you that these sins moses are anti arthrosis that have a little or an average amount of movement. Now, interosseous membranes are also closely associated with these SSIs and these are very broad sheets of dense connective tissue, either dense, regular or dense, irregular connective tissue that are found between certain bones. And so let's take a look at our image down below where we can start to piece some of these ideas together. And so notice here in the middle, we have a person and we're focusing in on specific regions of their skeleton. And so notice on the left hand side, we're focusing in on the person's lower leg. And so you can see the tibia here and the fibula over here and notice that zooming in on the distal portion of the tibia and fibula, we can see that there is this send osmosis here connecting the tibia and fibula at the distal end. And so that is going to be a ligament made of dense irregular connective tissue. Now, you'll also notice that in between the tibula and the tibia and fibula is this broad sheet of dense connective tissue, the inter membrane. And so uh notice on the right hand side, we're focusing in on this person's forearm. And you can see the ulna here and the radius over here and notice that between the radius and the ulna is another interosseous membrane. However, notice that the protein fibers in the interosseous membrane between the illness and the radi are longer and broader fibers. Whereas the fibers in the in interosseous membrane between the tibia and fibula are shorter fibers. And so it's not quite as broad. And so the shorter fibers between the tibia amphibian fibula uh are not going to accommodate as much movement. And so this is going to allow for less movement, whereas the longer fibers that we can see here between the radius and the ulna are going to allow and accommodate more movement. And so this is why our forearms or partially why our forearms are having are able to have more movement and accommodate more movement than our lower leg. And so this year concludes our brief lesson on Cinda Moses and we'll be able to get some practice applying these concepts and learn more about other types of joints as we move forward in our course. So I'll see you all in our next video.
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example
Structural Class: Fibrous Joints Example 3
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3m
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So here we have an example problem that asks which of the following statements is false. And we've got these four potential answer options down below. Now, option A says that sends moses are unique and that they are the only fibrous joint that are anti arthros. And so recall from our previous lesson videos that we've only covered three types of fibrous joints and those are sutures, gums. And now Sindiso now recall that the sutures and gums are classified as sin arthrosis, meaning that they are still or stationary joints that essentially allow for no movement. They are immovable joints, but the most are the only fibrous joint in our lesson that are considered amphiarthrosis. And recall that the A in anti arthrosis can remind us of the A in a little movement or the A in average movement. And so amphiarthrosis allow for a little or slight movement. And so it uh option A is true, but because option A is true, it's not the false answer option that we're looking for. So for that reason, we can eliminate answer option A. Now moving on, option B says syndesmosis are composed of loose connective tissue to allow for free movement. However, recall from our previous lesson videos that fibrous joints usually are made of dense connective tissue, usually dense irregular connective tissue. And that is the case for these sends moses as well. They're not made of loose connective tissue, they're made of dense irregular connective tissue. And so for that reason, this makes answer option B false and because it is false, of course, this must mean that it is the false statement that we are looking for. So answer option B is going to be the correct answer for this problem. And so we can mark it as correct. And so now, uh let's take a look at option C and D just to be sure. Uh Option C says that syndesmosis are the only type of fibrous joint that can be found in the appendicular skeleton. Now recall that the other two types of fibrous joints, which again are the sutures which are found in the skull and the gums which are found in our gums in our mouth. Those are part of the axial skeleton. And so really the sins moses are the only uh type of fibers joint in our lesson that can be found in the appendicular skeleton. And so for that reason, option C is true. And again, because it's true, it's not a false statement that we're looking for. So we can eliminate answer option C. And then option D says that the connecting fibers of sins moses are generally longer than those in sutures. And so recall that in sutures, the bones of the skull are going to be really, really close together. So really, there's no need for the fibers to be very, very long if those bones are already really close together. Whereas in Moses, the bones are further apart and so longer fibers are needed. And also they tend to have more movement since they are anti arthrosis. And because uh they have more movement, they will need longer fibers as well. And so option D is also a true statement. And again, because it's a true statement, it's not the false answer option that we're looking for and we can cross it off. And so this year concludes this example problem and I'll see you all in our next video.
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Problem
Problem
Fibrous joints are all functionally classified as synarthroses because they don't allow for movement.
A
True
B
False
13
Problem
Problem
How does the length of ligaments in syndesmoses affect the joint?
A
The longer the ligaments are, the more movable the joint.
B
The shorter the ligaments are, the more movable the joint.
C
The length of ligaments has no effect on the joint.
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