All right. Let's go ahead and get started on articulations chapter nine. Just so you know, there are some slides that are represented here that I cover in the lab recording next week for articulations in lab. So if i don't cover them here, i will be covering them there. When we talk about articulations, these are joints. And one of the things that we commonly associate with joints is movement. What we're going to learn is that in fact there might not even be movement at all at a specific joint. Maybe there is a little bit of movement. But not all joints have the same types of movement. So we're going to talk about that today. One of the things that i really like about this image from your text, is it actually represents the different types of cartilage and where you might find those different types of cartilage in relation to the joints that they make up. So just as a reminder, we build on unit one and our understanding of tissues and histology for the rest of the semester. Here we are applying our understanding of cartilage and the different types of cartilage to where we find them in articulations or joints throughout the body. Here at the top represented in the blue, you might see that there's that watercolor background of the extracellular matrix. This right here represents the hyaline cartilage. Here we have fibrocartilage. You can see all of those great collagen fibers that provide strength to the fibrocartilage that's represented in red. And then at the very bottom, bend and snap. That flexibility that we have of the elastic fibers here is the elastic cartilage in purple. So we know, or commonly associate the elastic cartilage with our ears, so you can see that here. But all these other joints here that you see in blue, those are going to be hyaline cartilage. You might remember from bones that the articular cartilage, at the very ends of bones to prevent friction of the brittle bones as they come together at an articulation is hyaline cartilage. So that's why you're seeing it at all of these different places where bones come together. In red, you see along and in between each and every vertebra and as well as between the hip bones we see that fibrocartilage. Remember fibrocartilage is in places where there's great stress, and so between the vertebrae holding us up and between the pubic bones, that is going to be where we need to have that strong cartilage. So when we talk about articulations or a joint, a joint or articulation is where bones meet either another bone, which is what we commonly associate with but, those bones can also meet cartilage that can also be a joint. And also even where bone meets teeth. So if you think about the maxilla and the mandible, those are going to be your jaw bone, right? Upper and lower jaw bones. Where your teeth sit inside of alveoli, these little pockets within those bones. Those are joints as well. When it comes to the mobility, so the movement of an articulation and the stability, there is an inverse relationship. Meaning as one goes up the other one goes down and vice versa. That is articulated here or illustrated here where mobility for instance, think about your shoulder joint. I don't know if you've ever had a dislocated shoulder but that's a very common injury. Your shoulder has incredible movement if you move around your shoulder all kinds of movement in every direction. So when we talk about the shoulder and the types of movement we can have, one of the ways that you can describe that movement is by axes. So if you think about a graph there's the x-axis, the y-axis, they run perpendicular to one another. And then z-axis would be kind of coming out of a screen so to speak on a graph. Our shoulders are multi-axial, meaning we can move them in all kinds of different directions. But with that mobility, we also have less stability. So while we can move our shoulders quite a bit, they are also unstable and that's where we have more injury as a result. So with our shoulders also known as our glenohumeral joint, very very mobile but very very unstable, okay? So there's the inverse relationship there. Let's look all the way on the other end it's sutures. Sutures are where the skull bones meet. And so i have started to introduce some of the sutures in lab, you'll see that this week. So we have for instance maybe it's the lambdoid suture right back here. Maybe it is the squamous suture. Maybe it is a sagittal suture, which is right between the two hemispheres. Each of these is a joint because it's where two bones meet. However you would hope that there is not a lot of mobility there. We do not want a lot of movement between those bones. We want those joints to be nice and stuck. With that said, while the mobility is very little if at all, they are very very stable. So again as stability increases mobility decreases. As mobility increases stability decreases. And that's the inverse relationship between mobility and joint stability. One of the things i just want to bring up right here, you will have an opportunity in lab and in your objectives for lecture to identify specific features of joints. When it comes to the glenohumeral joint, this is a synovial joint. mManing that it has a ton of movement functionally. The glenohumeral joint also has another joint associated with it. There's actually two joints here this is the acromioclavicular joint that i have up here at the top. So that's one separate joint. And then down here we have our glenohumeral joint. So just to so you know there's two joints here that you're going to be identifying separately. The glenohumeral joint, gleno is associated with the glenoid cavity or glenoid fossa of the scapula. And the humeral joint is associated with the humerus part. So gleno is associated with the glenoid fossa of the scapula and the humerus. That's where you get the name glenohumeral So there are two ways that you can classify joints. You can classify them anatomically. Remember anatomy and structure those are one and the same, and you can classify joints physiologically. In other words by their function. We are going to tie these two together. When we talk about the structure, what is that joint made of?Uum is it does it have a synovial capsule? And we'll talk about all the components of a synovial joint a little bit later. Are there a bunch of fibers? So is there fibrous tissue there? Is it made of cartilage? All of these are different types of structures that we're going to talk about here in a second. That's the anatomy and that's one way just to classify our joints. The other way we can classify them is by the mobility or stability of the joints. So we're going to specifically classify them when we talk about the function by the mobility, how much they move. But you now know that we can relate the stability of that joint to its mobility. So if i talk about a joint that moves a ton, i know that that's also not a very stable joint and vice versa. So first structurally. So this is our anatomical classification. Our three different types of structural classification are fibrous, cartilaginous, and synovial. When it comes to fibrous think fibers. And more specifically what are those fibers? They're collagen fibers. The tissue that is going to make up our fibrous joints, and we're going to see specific examples that we want to be aware of is dense regular connective tissue. Remember that our collagen fibers are all going to run in one direction which then tells us that we have strength in one direction. So those are going to be our fibrous joints. The second type is cartilaginous. What is that made up of? Cartilage. And hopefully you can hear cartilage in the name cartilaginous. Finally, structurally we have synovial. There are several different types of synovial but when it comes in terms of function, but when it comes to the actual structure, they are all going to have a synovial capsule with synovial fluid contained within. So when it comes to the functional classifications, there are three different types of movement that we can associate with our joints. The first one is synarthroses. When we say synarthroses that's plural, remember with an i synarthrosis is singular. The second is amphiarthroses. Again i would be singular, ampiarthroses is plural. Same thing here with that e so diarthrosis, diathroses, singular, plural. That's our third type. Again these are all based on the type of movement we can have. There is a way that i remember these. So if we're talking about synarthroses. Synarthroses are joints that are immobile. I think synarthrosis, so not moving, okay? So synarthrosis so not moving. Amphiarthroses has a little bit of movement. So slightly mobile amp- amphiarthroses, a little bit of movement And then when it comes to diarthroses, that is a freely mobile joint. All kinds of movement. There's two ways i can remember this. One is a little bit crass, the other one i like to include as the more —the nicer way to say it, but diarthroses i could die there's so much movement. That's the nice way. Another way that you can think of it is diarrhea. Freely flowing like diarrhea. So i could die there's so much movement, diarthroses or diarrhea, freely flowing like diarrhea, diarthroses. So hopefully those help you to remember. All right so we're going to come back to our structural classification, and we are going to associate specific examples of each structure with the function as well. So we're going to categorize by the anatomy and then associate the function in terms of the movement with that. The very first type —remember this is our structure or anatomical classification is going to be the fibrous joints. So remember these are going to be dense regular connective tissue, that's what's going to make them up, and there's no joint. So there's no synovial joint here. Nothing like that, there's no cavity. The joint just comes together. I do need you to know the specific examples of fibrous joints. So there are three different types of fibrous joints. There is gomphoses, there is sutures, and there's syndesmoses, okay? So those are the three types of fibrous joints i need to know. For the gomphoses i think gums. And specifically gomphoses are where the teeth meet either the maxilla or the mandible. So this one up here is an example of a gomphosis. Every single joint where a tooth meets, either the maxilla or the mandible is a gomphosis. Collectively they're gomphoses. So what you have here, all these white lines are representing the dense regular connective tissue that you have connecting the two bones. We don't want movement here. So the function of gomphosis is synarthrosis. So not moving. We do not want our teeth to move. I don't know if you've ever had one of those nightmares where your teeth fall out, i sometimes have those, other than when we actually lose our baby teeth we really don't want movement at these joints. So if you do have movement, maybe that represents gingivitis, maybe gum disease, or something else. But in a normal healthy situation of these joints, synarthrosis, so not moving. The oh and then again how i remember this is gomphosis, i think gums. Sutures. That is where the skull bones meet. So again we talked about lamboid suture, um squamous suture, sagittal suture, coronal suture. All of these are examples of sutures where the skull bones meet. Again, so not moving. We do not want any movement here. So it is synarthrosis functionally, and then sutures, hopefully you hear in the name, so if you are familiar with and start to memorize the different types of sutures that we find between the cranial bones, automatically sutures tells you what that is. The third and final type of fibrous joint is syndesmoses. These are going to be between parallel bones. There's two good examples of this, one you're finding here. As you start to learn about the appendicular skeleton, so our upper and lower limbs, this represents two parallel bones within your upper limb. More specifically in your forearm or antebrachial region. The two bones we find here are the ulna and the radius. Notice that they run parallel to one another. There's actually a joint in between them. And this helps them kind of move like one even though there's two separate bones. This joint, you can have slight rotation. So imagine —so try and hold your elbow still but rotate at the wrist and take a look at your forearm when you do that. You'll notice that there is slight rotation between those bones. So your wrist can move while your elbow doesn't. This joint in terms of the function has a little bit of movement. So that is amphiarthrosis. We specifically call this joint the interosseous membrane between these two. Another example would be between your tibia and your fibula in your lower limb and that has the same type of setup. So it's also going to have an intraosseous membrane between those two bones and it's two parallel bones. Same thing, amphiarthrosis. When we look at the overall functions of our fibrous joints, i want you to notice, of the functional classifications we can have, we see synarthrosis for gomphoses and sutures and we see amphiarthrosis. So fibrous joints do not provide us complete flexibility that we would see with diarthroses. We only have either no movement or a little bit of movement that's provided by fibrous joints. Just to give you an overall view. So fibrous joints is our first structural classification, now we have some examples of that. The second type of structural classification that we have again is cartilaginous joints. Cartilaginous joints again have cartilage, and we do not have any cavity here. So there's no pocket, there's no space with fluid inside. It's just two things coming to contact. In this case cartilage provides that contact at the articulation point. There are two specific examples of cartilaginous joints that i need you to know. The first type is synchondrosis and the second type is symphyses. Synchondrosis, hopefully you hear chondro in the name. That tells you cartilage. So that one's probably the easiest to remember in terms of being cartilage. More specifically the type of cartilage that we're going to see at synchondrosis is hyaline cartilage. Where do i find hyaline cartilage? You might remember that we'll have hyaline cartilage at the metaphysis. So specifically the epiphyseal plate while there is still cartilage there, remember epiphyseal plate we still have lots of hyaline cartilage, it eventually will fuse the bones together and become an epiphyseal line. Another place where we would find our synchondrosis is costochondrial joints. When we say costochondrial, the chondrol is associated with the cartilage which you can see here, and the costo, costo means ribs. So costochondrial tells us that it's us it's the joint between the rib and the cartilage that meets that rib. I'm going to talk a little bit more in lab about their how they're slightly different joints in terms of movement that we can find between the ribs. But for now i just want you to associate the costochondrial joints and the epiphyseal plate with synchondrosis, and functionally we do not have movement. So this is so not moving. The second type of cartilaginous joints is the symphyses. The easiest one to remember because it's in the name is the pubic symphysis. If you can remember that the pubic symphysis is an example of a symphysis under the umbrella symphyses, remember symphyses is plural. What we have there is fibrocartilage. So where the synchondrosis are made of hyaline cartilage, the symphyses are fibrocartilage. Remember we need a lot of strength here. We're also not going to have a perichondrium where we have a symphysis because there's a lot of stress on these particular joints. Two specific examples of symphyses are the intervertebral joint. So we're seeing here. So fibrocartilage there, and as i already mentioned the pubic symphysis. Now we actually have a little bit of movement at these joints. I want to kind of draw your attention to your spine for a second. If you go ahead and move your thoracic region, so your upper body left and right, you notice you have what seems like a lot of movement in your spine, right? You can move from side to side quite a bit, however, we're seeing amphiarthrosis here. Each individual joint between vertebrae only has a little bit of movement. So there's amphetarosis between each individual vertebrae. However, when we combine all of those together, then we have great movement of the spine. So only collectively with each of our joints fully functional do we have full range of motion of the spine, but individually each joint only has a little bit of movement. So collectively if we're looking at cartilaginous joints and we look at the type of function that they have, again we do not see diathrosis for any of the cartilaginous joints. We only see synarthrosis, no movement for the synchondrosis and amphiarthrosis, a little bit of movement for the symphyses. That brings us to our third and final type of structural classification of the joints which is the synovial joints. Right off the bat, any time i say synovial joint, you are going to associate that with diarthrosis. Diarthrosis, that functional classification is only associated with the structural classification of synovial joints. Again if we take a step back, remember cartilaginous can be synarthrosis or amphiarthrosis, our fibrous joints can be synarthrosis or amphiarthrosis, but only synovial joints can be diathrosis. This articular capsule and the synovial fluid within it, provides for optimal movement. Lots and lots of mobility. Breaking up the different parts of a synovial joint into the different components or anatomy, we have the articular capsule, which is this purple region on the outside and then what's represented here in the light blue. So purple on the outside —inside and then the blue. We have the joint cavity. Which is represented on the inside. And there's synovial fluid on the inside of this cavity. So no cavity within the body is empty. There's always something in this case this cavity is filled with synovial fluid. We have our articular cartilage, remember that is at the edges of the bone, so that's going to be right here represented in white, and here, okay? And we have ligaments. Our ligaments are represented on the outside. They're going to surround the synovial capsule, so this right here in white is a ligament, and do we have a represent on the other side? No they only represent it on one side. But ideally you'd have one here as well. So those are our ligaments. And then all around and in you would have nerves and you'd have your blood vessels. So those are going to be throughout, with the exception of the cartilage. Remember that our cartilage is going to be avascular. So when it comes to our cartilage, specifically our articular cartilage here, remember cartilage is going to have chondrocytes in it. It's going to have chondroblasts and chondrocytes, and we need to be able to feed them and provide them nutrients. That's where the synovial fluid will come into play. So if we're talking about the articular capsule first. The articular capsule is made of two parts. The fibrous layer which is on the outside, okay? So that's what's being represented in this light blue. And the synovial membrane. The fibrous layer is superficial to the synovial membrane represented here in purple which is deep. The outer fibrous layer is made of dense irregular connective tissue. So we know that that's going to be, hopefully you can associate dense irregular connective tissue with having lots of collagen fibers. But those collagen fibers you might remember run in all kinds of different directions. And so our dense irregular connective tissue and that fibrous layer provides strength in multiple directions. The inner or deep synovial membrane is mostly going to be areolar connective tissue. We know that we have elastic fibers in areolar connective tissue and we know that we have collagen fibers. So we have some strength and some elasticity, and that's going to provide for protection and give of that inner synovial membrane. The areolar connective tissue we also know is going to have cells in. It it's going to have cells like fibroblasts. Fibroblasts create their environment. Remember cells make up what's around them. They make up the fibers and they make up the extracellular matrix. And so the fibroblasts within the areolar connective tissue, they're going to go ahead and create the synovial fluid that exists within the articular capsule. What is that synovial fluid important for? Um imagine like a water bed. If you were to jump on a water bed, oh don't do that but if you did jump on a water bed you have a lot of cushion. So the fluid absorbs a lot of shock that you might have between these weight-bearing bones. It also provides lubrication. So keeps it nice and fluid between these two bones, and another important part is that this synovial fluid has nutrients in it. It's going to have things that the chondrocytes present in the articular cartilage need. So having that synovial fluid available there through the process of diffusion we can get nutrients to our chondrocytes and keep them alive. The articular cartilage, i've already kind of highlighted there. We know that we're going to have chondrocytes there. What does the articular cartilage itself do? Well we know it's made of hyaline cartilage. It's not very strong, but it does prevent friction. So it's almost more spongy compared to for instance a fibrocartilage. This prevents damage of the of the bones. So at the epiphysis, it prevents damage. And we're actually going to find in these areas we do not have a perichondrium. The only place that you're going to see outside of our fibrocartilage where the articular cartilage doesn't have a perichondrium is within this space. Again because of stress and also because we have the protection of the synovial capsule. So we do not have a perichondrium here. Too much stress and we have the protection of the synovial capsule and the synovial fluid. Remember that cartilage is avascular. So again we're going to feed our chondrocytes within the articular cartilage with the synovial fluid. We actually can provide some strength to this cartilage, so just like the bone where you can have micro fractures, with exercise you can actually continue growth of this cartilage. However, you need to be careful because this cartilage is hyaline cartilage so it is weaker. It also means then that if you were to cause stress on these joints and affect the articular cartilage, because the articular cartilage is vascular, it is much harder to get to get it to grow back. So cartilage we have a hard time um regenerating. So with exercise, you can allow for more cartilage growth but it is slow to come back. As far as the ligaments, the nerves, and the blood vessels, the ligaments again are going to be on the outside of the synovial capsule. They help to provide strength and reinforcement for the capsule. So think about just putting a special protective extra layer on the outside of that capsule. And ligaments as a reminder we have ligaments that connect bone to bone. So you can see here we're connecting this bone with this ligament to this bone. It's almost like a i think of like a piece of tape connecting the two. There are two different types of ligaments, there are extrinsic ligaments and intrinsic ligaments. Most of the ligaments we see represented with our articulations are intrinsic meaning that they are in direct contact with the um the joint. So in direct contact with the joint. So this example right here, where it is in direct contact with the actual capsule and articulation, this is an example of an intrinsic ligament you're seeing here. Sometimes we'll have support of other ligaments that are outside but not in direct contact, and i'll try and draw your attention to that in the lab recording when i get to the specific types of synovial joints, but if it there is not direct contact of the ligament with the joint, that is extrinsic. So think uh outside extrinsic, internal or connected, intrinsic. And then finally if we have tendons, those are going to be where there's muscle that is connecting it's connecting between bone and muscle. And so you can have tendons as well. Here we do not have the tendons represented but that can be part of the different joints. Here is an example of a tendon. So just to show you on this one, here's a tendon here connecting this muscle to this bone, okay? And what we're looking at here is a lateral view of the knee. Some of the different accessories, some optional different components of synovial joints that you can have, i'm going to show you in these coming slides. So just these two. We have fat pads, we have bursa, with the e is plural, bursa would be singular without the e. And then we have our tendon sheaths. First and foremost are the fat pads. Hopefully now you can associate fat pads, you think fat, you think okay that's going to be adipose tissue which provides cushion and protection and temperature regulation. In this case, what we can do is we can have these fat pads and those are represented here with the yellow. So there's some fat pads there. You can see more fat here but within the joint. You actually see the fat pad right here. That's the best example of that. It's going to essentially fill in the gaps and fill in the spaces. So within the inside here you're seeing the capsule. And the capsule —here's the outside part of that cavity right there, excuse me the capsule. So we see that this fat pad is going to be anterior to that. Remember this is a lateral view. So it fills in almost like packing material. And in doing so provides cushion for those joints. Bursae are also going to help to reduce friction and provide protection but instead of being filled with fat, they're filled with synovial fluid. So it's not going to be the articular capsule itself but they're these tiny little baby pockets that are represented in blue here, and those are going to be filled with synovial like fluid. So think nutrients but mostly fluid created by the cells in that space, and in order to reduce friction in other parts of that joint, we have those bursae. Just to give you an idea, just some of the extra notes here. So the patella. This is a lateral view of the patella so that's your kneecap. And then this one right here is an infrapatellar bursa. Prepatellar bursa. All of these are going to be in front. One specifically directly in front of the patella, the other one just inferior to it, but they are anterior to the patella and again are going to help to prevent friction. Then we have our tendon sheaths. Tendon sheaths are really going to be bursa. So again think of them being filled with synovial fluid, little pockets of synovial fluid filled areas or structures. And where we find these tendon sheaths are around tendons. So if you look at your hands, you kind of move your hand around. Toward where your knuckles are you might be able to see individual movement. And there are some regions of those digits and those specifically those tendons that aren't covered by bursa. Usually in those areas, that's where you do not have tendons coming together. There's a little bit of space between them. So we're not worried about them rubbing against each other and causing friction and damage. But in the dorsum of your hand, if you look at that area, you really can't see individual tendons when you move your digits, and that's because we have a tendon sheath that's going to cover those tendons and separate them from one another. So again it's really about preventing friction between the different tendons connecting or coming into contact with one another or with the neighboring structures around them. So now that we know the different components and the anatomy of a synovial joint, we want to be able to identify the types of synovial joints. So we know already structurally, if we talk about the different types of joints, we have our fibrous, we have our cartilaginous, and what we've been focusing on here is our, sorry just bringing it down, here synovial. We can further break up synovial anatomically by things like their shape, so the actual shape of the synovial joint surfaces that come together, the types of movement that the joints can provide, so not all movement is the same, and then the planes of movement. I told you previously with the glenohumeral joint, your shoulder joint, it is actually a multi-axial joint. You can move it forward, back, you can rotate it in circles, it goes in all times types of axes or planes. So that's multi-axial. But not all of our joints that are synovial move in all the different directions. Just because we can have a lot of different a lot of movement at a joint does not mean it moves in every single direction. For instance if you think about your elbow, if you flex your elbow you have a lot of movement of that joint but it only moves in one plane. If you actually move your hand or your um try and move your elbows side to side, like left to right, that movement actually comes from your shoulder. So really the only movement that comes specifically from your elbow joint is when you flex it, and that is in one plane. So i think for this part it's helpful to see me so i can act out some of the different movements that you can see at some of these different synovial joints. First remember that we can further classify our synovial joint by shape. So there are six different shapes that we find within synovial joints. The very first one is planes which we're seeing here. We also have our go through our hinge joints is number tw,o three and four that's pivot and condylar joints and then we have saddle joints number five, and ball and socket number six. So those are the six different shapes of synovial joints you can have. Again all diarthroses but the movement slightly differs in what we're capable of at those joints based on the shape. And so i'll try and explain that with my hands here. The very first type of shape is plane. So with plane i want you to think flat surface, flat surface. rRally here you can't have movement all around, right? This joint doesn't do this, they're stuck here. So really all we have is sliding back and forth at a plane joint. So of the joints, this is the most simple, and it has the least movement of the diathrosis types of movement. We can only move here in one plane. So here, even if it was side to side, it's still going to be only really just one direction, and so that's going to be uniaxial. So movement in one axis. In this cas,e um when we talk about these, uh again it's gonna be a flat surface between the two, so both sides are flat, and a really good example of this would be intercarpal and intertarsal. Now when we talk about these examples of these different shapes, um the names look fancy but you can break it down to what the name says. So intercarpal, you're going to learn in lab that we have our carpal bones. Our carpal bones are our wrist bones. In between those carpal bones, our wrist bones, those are joints. Because remember it's where bone meets bone. So between the wrist bones, those are plane joints, and also between the tarsal bones. So these are carpals right here, these are your wrist bones, and then your ankle bones are tarsals and you'd find the same thing in your ankle bones. The second type of shape is a hinge joint. That is going to be your elbow, your knee is also an example of that, and then in between the phalanges. We're going to learn that our phalanges are our our finger bones, okay? So you have a couple different sets of those proximal, middle, and distal. When we talk about these we only have one plane of movement, okay? So uniaxial. I can only move this direction. If i was to do this, that is an entirely different joint that's coming down here. So only one axis of movement. Elbow. One axis of movement, same thing with your knee. So how do we allow for this hinge joint movement? We are going to have one surface that is concave and the other one that is convex, okay. So it's not a perfect circle and that's important because that prevents us from having different axes of movement outside of the one that we have. But think of like a trough and then putting a cylinder inside, okay. So we can have movement in that one axis that way. Um again, the elbow is a good example of this, the knee, and then in between the phalanges, so in between your finger bones. Third is a pivot joint. So the very best example is saying no with your head. This is an example of your pivot joint. Yes is an entirely different set of joints, okay. So it's only the no version. Specifically how do we allow for that. I talked about this in the lab recording but your C1 and C2, so C1 sits on top of C2, that dens process of C2, we rotate around that, okay. So here's C1 our first cervical vertebra and it rotates like this around the dense process of C2. So this movement is side to side, that's the only movement we get from that, it's in one axis so that's uniaxial. Again we come around the dens process and we have a ligament that holds it in place. And that's what you're seeing right here. If we talk about uh their best example again that's C1 and C2. Also the proximal radial ulnar joint. Let me break that up for you. So in addition to your elbow joint there's a couple other joints in close proximity to your elbow. One of them between the radius and the ulna right here, there is actual rotation around that too. So a lot of this rotation that we get here— i don't know if you can see me moving my wrist, that is going to be from that proximal radial ulnar joint. So that's a pivot joint as well. Um i think i was going to try and give one more but i forget. O think that's it. Okay. Oh um i did want to tell you if you wanted to provide the name for the C1 and C2 atlantoaxial joint. So that's the fancy name for this joint. Um i want to provide this for you to just get you thinking about these names in terms of what they are, they bring two parts together. The atlas is the atlanto part, the axial is the axis. You might remember C1 and C2 are the atlas and the axis, that's where the name comes from. All right number four is a condylar joint. So i've been talking about for instance, plane is two flat surfaces, when we talk about a um hinge joint we have kind of like a trough and like a cylinder kind of thing, sorry like this um our condylar joint has a convex and a concave shape. But what i want you to notice is their oval, okay. This is really important because this is very different than ball and socket where we have kind of a circular, kind of a crater like the glenoid fossa and a ball, that's not this. The oval shape of the convex and concave surfaces actually limits the types of movement we can have. So instead of like the ball and socket, which we're going to see in a little bit having multi-axial movement, because it's oval it can only go in a couple different directions, okay. So one direction or one axis, the other direction, but we don't have the ability with this shape because both both articulating surfaces are oval, we don't have multi-axial. So we have back and forth, we have side to side, but again biaxial. A really good example of this is metacarpophalangeal two through five. Let's break that down. Metacarpals are the next set of bones, the more distal bones compared to the carpals. So if you haven't had a chance to look at your appendicular skeleton, the upper limb for for lab yet, it goes carpal bones which are your wrist bones, metacarpals which are these longer ones, and then we have distal to those we have our phalanges. So where the metacarpal bones meet the phalanges, that is what we're talking about right here, okay. And specifically it is two through five. So when we actually number our digits, your thumb is one, then it goes two, three, four, and five. Your pinky finger being number five. We're not talking about the thumb here, this has some special other joints going on, or special types of movement. We're specifically talking about two, three, four, and five. Now again it is where, it's kind of within this region of your hand, but where the metacarpals meet the um the phalanges, you can have back and forth movement and you can have side to side. If you try and force this this actually comes from movement of several joints. This is not actually that movement. So back and forth, side to side you have biaxial movement of the metacarpal phalangeal joints. Number five is the saddle joints, okay. So what i want you to watch here's like like you're sitting in a saddle like this, okay. So both of them have kind of a cup shape to them. This again because they're not ball and socket because they have these kind of convex and concave kind of oval shapes so to speak, it's not quite oval here but trying to explain it but kind of this shape, it limits the movement. So we're not multi-axial here we're biaxial. We can go this direction, okay. That's one axis. So here. And then i can also move this one, okay. So i can move this one back and forth which provides one axis of movement, i can move this one which provides one axis of movement. So that's biaxial. Good example of this is your first carpometacarpal, okay. Your carpometacarpal for the first digit is saddle. And that's different from two through five. That allows for you to have more movement here. It's almost like a swinging movement. So i can go here, and i can go back and forth here, okay. So that's a saddle joint and specifically you get those movements again from the saddle joint within your thumb. We'll talk about some of the other movements you can have too. All right. Final is ball and socket. Ball and socket is the one that provides multi-axial movement. So being perfectly circular and having a crater-like surface to go into allows for all kinds of movement within that joint. Remember this is the all of these are very uh very unstable but definitely the ball and socket is going to be the least stable because of all that extra movement. Examples of this include your hip and your shoulder. So we know we can very easily dislocate our shoulders, but we have all kinds of movement that can come. I can move this direction, I can move this direction, I can rotate around. All of that's going to come from our glenohumeral joint also known as our shoulder joint. So this video I actually provided for you in the extra chapter 9 helpful resources, but i'm going to go ahead and walk through it with you since there's no narration, to it i'm going to provide narration for you. All right so for this video we're going to go over the six different shapes that we find for synovial joints and their movement. When it comes to a synovial joint, we know that it has a synovial capsule with synovial fluid. The very first one that we're going to look at is the ball and socket joint. We know that this has a ball and a socket which allows for multi-axial movement. So multiple planes of direction. In this case or this example here they're showing you the glenohumeral joint where the head of the humerus meets the the glenoid fossa of the scapula. The second one that they're showing here in the video is a hinge joint. Uniaxial, so one plane of movement between a convex and a concave surface. The example here is the knee joint, more specifically the distal part of the femur where it meets the proximal part of the tibia. Third up is the pivot joint. The pivot joint allows for side to side movement, so uniaxial. Where a round surface here shown the dens of C2 is surrounded by a ligament ring. Fourth is the condylar joint. Oval convex and oval concave surfaces, this is biaxial movement. My example for you was the metacarpophalangeal joint two through five, but the example shown here is actually between the radius and the scaphoid and lunate bones. Sorry i was going kind of fast i wanted to show you again. The example they're showing here is actually between the distal part of the radius, so you're seeing that up here and the scaphoid and lunate bones which are carpal bones. This one is the saddle joint. Saddle shaped bones, biaxial movement. So two planes and specifically this is the first carpometacarpal joint. So this is where your thumb is and that allows for opposition of the thumb as well. This final one, let me go ahead and pause it here. So for our purposes the intervertebral joints are cartilaginous joints, and specifically we would consider it a symphysis, however, with more detail and um that you're not required to know for our purposes, technically the intervertebral joints there are both plane joints and there are cartilaginous joints there. So they are focusing on the synovial joints here, specifically the plane joints that are available also between the vertebrae, and what we can see is that it is two flat surfaces that glide back and forth on one another. So that is the plane joint and the final of the synovial. All right. Again we have our synovial capsule, synovial fluid, articular cartilage, ligaments on the outside, and hopefully that gives you a better visual representation of the different joints we have for synovial. So that brings us to the very final part of synovial joints. We have focused on them in terms of the types of synovial joints in terms of their structure and what types of surfaces or surfaces are articulating with one another, we've also talked about the different shapes of synovial joints, and we're finally going to end with the movements of synovial joints. There are four different types of movement, and we really have been talking about them already but we're just going to give them specific names now. So four different types of motions, there's gliding, angular, rotational, and then special movements. And the following slides after special movements are all examples of special movements. So first and foremost, we have our gliding. That is going to be again between the carpals, so the intercarpal joints are the intertarsal, that's the back and forth i was showing you with the flat surfaces, that's gliding, okay. So associate that with gliding. The second type is angular. That is where we are changing an angle, okay. So there are two different types of angular motions we can have. The very first type is extension and flexion. So what i want to show you here is an example here. When i flex, which you're probably comfortable with with the elbow, i am decreasing the size of this angle, look. Decrease in size of the angle. If i extend i'm making the angle bigger. So decrease the size of the angle is the flexion. Extension is increasing the angle. If we go past the point of that flat, so we're actually kind of beyond the perfectly linear line, that would be hyperextension. This is different from abduction and adduction. So abduction, i want you to think angle gets bigger, and adduction i want you to think a decrease in the angle. More specifically instead of extension and flexion like we have, this is going to be in relation to a midline. I'm going to use my hand as an example even though it's not at the body, and i'll show that in a second, but imagine there's a middle line down my hands, okay. If i want to make the angle bigger, i'm going to go like this. Do you see how all of these fingers went away from the midline? And so that is going to be an example of bigger abduction. If i want to decrease the angle and come closer to the midline, i adduct. So abduction make the angle bigger, adduction decrease the angle. It's really in relation to the midline of the body though. So i want to show you, i don't know if you can see, if i from the midline of my body bring this arm out in a way, i'm making the angle bigger away from the midline so that's abduction. If i want to make that angle smaller and decrease it i adduct. So abduction bigger, adduction smaller, okay. So hopefully that gives you a good idea of the difference between the two. Rotational is where we actually rotate around an axis longitudinally, okay. So atlantoaxial —sorry i should fix that for you just make a note atlanto sorry with the t —so the atlas and the axis, the no gesture. So this is a longitudinal movement, okay. And some other examples we have are medial and lateral rotation and pronation and supination. First and foremost again this is coming to and from the medial plane. So i want you to watch my shoulder. If i'm going to rotate immediately, i'm going to come in towards the midline ,so this is bringing my shoulder in, okay. zdo it's like this koi little look, hey. And if i want to laterally rotate and go away from the midline, rotate the shoulder backwards. So you like someone, hey. Medial rotation. You don't like someone, hey. Lateral rotation. Pronation and supination we can do with our hands and our wrists. It's all about the thumbs. So for instance if i was going to put my palms and face my thumbs away from the body, in order to put myself in anatomical position, i am kind of holding like a cup of soup, and so rotating this direction is supination, okay. I also think when you do good on an exam, you rotate thumbs up, super. Alternatively if i go this way, boo like rotating inwards and medial. That's going to be pronation. I think i did poor on the exam. Pronation, poor. So pronation, this direction. Supination, this direction. That brings us to our special movements. And there's several different types of special movements. Depression has become away, okay. So we're pushing down towards the axial body, towards the torso. Elevation think elevator, right? We're elevating so that's bringing the shoulders up towards the head. So depression down, elevation up. Another special movement —i'm not going to show you my foot but flexing the foot, imagine this is my foot. Dorsiflexion is going up towards the dorsum, okay. So dorsiflexion is up and more superior. Plantarflexion is remember plantar region is the bottom of the foot, the plantar region, so that's plantar flexion. So we're flexing, we're decreasing angles here but it's specifically up towards the dorsum or down towards the plantar region. Then you can take the foot and you can invert it or evert it. Now this slide is a little bit confusing, imagine these are both your feet. Inversion is inward, okay. So inversion is inward towards the midline. Eversion is outward, okay. So inversion of the feet in towards the midline, eversion is out. And this one's super fun you can see this guy protraction. So we're going forward and away from the neck, right? Retraction coming in, okay. And then finally our thumb allows us to have opposition. Which is bringing together the thumb and the little finger or digit five, okay. So opposition another special movement we have. All right the rest of these will be covered in lab next week in our articulations lab recording. So there's very specific ones that you need to know, um specific synovial joints, and you want to be able to know all the components of them. You want to know your shapes, your movements, the different planes, is it multi-axial? Biaxial? You need to also know the different types of ligaments that make it up. So we will go over this in lab together. Hopefully this lecture was helpful. Reach out if you have any questions.