okay so today we begin unit three which completes the last part of the skeletal system uh we're going to end up talking about the joints today where previously we talked about uh bone formation we talked about the axial and appendicular bones now we'll talk about the places where the two bones meet and we're going to classify joints based on their structure and their function we're going to see over here on the left the class handout that's just a couple of pages we're going to sketch a typical synovial joint and you've got some matching questions there about different types of synovial joints or just different classes of joints based on their structure or their function so it'd be good to have the class uh handout close by as we go through these slides i've also included on uh d2l a handout of the pages that are going to be important for unit 3 from the lab manual and you'll notice that it's all muscles so there aren't going to be any joints that show up on the lab practical part so there's really no lab part to this particular lecture but you'll see there are a bunch of slides that give us plenty of examples of the different types of joints so you may see these things show back up on multiple choice questions maybe on the next exam so let's jump into some of these slides as i mentioned before this powerpoint is going to continue with the last part of the skeletal system where we focus really on the joints and these are sometimes referred to as articulations which specifically refer to the site where two bones meet and we're going to see that these articulations of these joints are important because they give the skeleton some flexibility uh it's the parts where the bones are held together the downside however is that these joints are also going to be the weak points in the armor if you've ever seen things like a swarm of ants attack another insect that has an exoskeleton you'll notice that they're always stinging right there in the joints because again those are going to be the weak parts of even the exoskeletons on insects that happen to have that type of skeletal system okay in this slide we can see that where two bones meet there are often an extensive amount of ligaments which we can think of as just a bone to bone connection in fact you can see several different ligaments are named here you've got this tibial ligament sometimes called the medial ligament and it's going to be a ligament that goes from the femur to the tibia there is a fibular ligament that goes from the femur to the fibula you can see there is a ligament that goes from the patella to the tibia that would be the patellar ligament but above that you can see there is a connection from bone to muscle and that's going to be referred to as a tendon so a bone to muscle connection is a tendon but any bone to bone connection is going to be a ligament there are a couple of ligaments we can point out in addition to these superficial ligaments and those are going to be some of these interior ligaments all we've done here is we've kind of cut that tendon of the quadriceps and we've pulled that patella forward and we're now looking behind the patella and you can see kind of right in the center of the knee there are a couple of additional ligaments one of them attaches more anteriorly to the tibia that's the anterior cruciate ligament and then there's a posterior cruciate ligament that attaches more posteriorly to the tibia and those are just going to kind of keep the knee from sliding around on the tibia there they anchor it to that tibia a little bit better you can again see from the side view here the anterior and posterior cruciate ligaments and and how they just try and fix that femur to the top of the tibia you can also see from the side view that patellar ligament and that quadriceps tendon so we're going to look now at the functional classes of the joints and the functional classes are based on the amount of movement that they allow the joint to do we're going to see these are going to be broken into three functional classes there are the syn arthroses which are going to be immovable joints you can think of something like a tooth socket the amphiarthroses which are slightly movable this would be something like that pelvic joint the pubic symphysis which doesn't typically move but in the event of something like childbirth would move slightly and then diarthroses which are going to be freely movable joints will refer to these also as synovial joints something like the wrist is a good example of one of these freely movable joints we're going to see in addition to function joints are going to be broken down based on their structure as well and that just means what kind of binding material is used when we're attaching these two bones are they held together by fibers that would be a fibrous connection if they're held together by cartilage that's a cartilaginous connection and if they're held together by a synovial membrane then it's going to be a synovial joint we're going to see those are usually accompanied by some type of cavity filled with synovial fluid in fibrous joints we're going to see bones are going to be held together by dense fibrous connective tissue there's typically no joint cavity and these tend to be the syn arthroses those immovable joints we'll see three examples sutures in the skull syndesmoses which are going to be in the ankle and gomphoses which are going to be those tooth sockets so here would be one example of a fibrous joint we've got the sutures in the skull you can see those dense fibrous connective tissues really connecting these two bones then syndesmosis these are going to be a fibrous connection between two bones this happens down there between the tibia and the fibula down at the distal end where they're attached around the talus there are lots of these ligaments that lock those bones together and when you're just sitting there taking notes or listening to this lecture those are not moving so they're they tend to be immovable if you were doing something like running some bleachers or running up and down you know a lot of stairs then in those situations this might move slightly so it's sometimes classified as a slightly movable joint and then gomphoses are examples of peg and socket joints and a good example would be the tooth sockets here you can see that periodontal ligament that anchors each tooth down into that tooth socket we're going to look at cartilaginous joints next we're going to see two examples of these cartilaginous joints the synchondrosis and then symphyses a sin chondrosis is going to refer to one of these immovable joints which that's the prefix their sin and then chondrosis tells us cartilage so we're thinking of one of these immovable joints that's held together by cartilage this is often involving hyaline cartilage some examples would be that epiphyseal plate that you see on the proximal end of long bones another example we can see here that first rib as it attaches to that manubrium that's another one of these synchondrosis next we'll see symphyses these are going to be held together by a piece of fibrocartilage so i mentioned that pubic symphysis earlier that holds the two pubic bones together but we'll also see examples like the intervertebral discs which are again a patch of fibril cartilage that are going to be holding those two bones together these tend to be slightly movable and last structural class of joints are going to be synovial joints these are held together by a synovial membrane and they usually involve some type of joint cavity filled with synovial fluid and that synovial fluid acts as a lubricating fluid that helps prevent damage being done when these two bones are moving past one another you can see in addition to the synovial membrane which is kind of shown in green here there is a layer of articular cartilage that lines the two epiphyses of these bones again trying to prevent these two bones from actually grinding together and doing damage there are other structures that are there to reduce friction and prevent damage from being done one example would be a bursa you can see that here in this little green circular structure that green structure again is our synovial membrane and it's it's filled with this little patch of synovial fluid and it's going to act as little ball bearing where it's going to situate itself between bones and any kind of ligaments or tendons or muscles that happen to be moving past that bone it's just going to kind of get in the way and prevent any damage from being done again bursts are going to be kind of round ball bearing shaped we can see that in this next picture here you can see as the tendon or the muscle moves that versa moves with it preventing any of the the tendon rubbing against the bone there now there's also something called a tendon sheath which does the exact same thing as the bursa in fact you can see the bursa up here at the top of the picture and then below that you can see a much wider and longer synovial membrane again in green and this one is kind of like a long sheet that wraps around this tendon this is going to be called a tendon sheath and again it's made of the same thing as the burst it's just much longer and wider and is more sheet like so more part of that is a tendon sheath you can see that a little bit better on this next picture again it's job is to prevent any of that tendon or ligament from ripping against the bone so now we're going to look at different movements that synovial joints are capable of and this is just going to allow us to get familiar with different vocabulary terms i'll try and give examples of each of these movements we're going to see examples of gliding movements this is going to be done by some of the short bones on the wrist we're going to see some angular movements we'll talk about flexion extension and hyperextension and give some examples of those we'll talk about abduction and adduction as well as circumduction we'll look at rotation both medial and lateral and then a list of special movements i think there might be six or so of those special movements so let's jump into those first one we mentioned were the gliding movements and this is going to be done by flat bone surfaces that glide across one another we mentioned some of those carpal bones and the wrist as well as the tarsal bones and the ankle are going to do this type of movement you can see in a gliding motion you can really kind of move forward backwards up or down you can kind of move the hand in just about any direction with these gliding movements the next are the angular movements and these are as their name suggests going to be much more angular so here are some examples of what we're talking about so flexion is going to be any time you're reducing the angle and this can be done by flexing at the knee you can see as she pulls her ankle up kind of towards her thigh there this is going to be flexing at the knee and then when she straightens her leg back out that's going to be extending the knee again you wouldn't want to go past that or and hyperextend the knee that would be kind of painful abduction is going to be movement away from the middle line and you can think if somebody uh is abducting somebody there they grab them by the arm and pull them away from somewhere so your arm maybe that's a terrible analogy but again your arm is getting pulled away from the midline so that abduction like somebody's getting abducted that that has to do with again their arm getting pulled away from the midline so there are muscles that do that they move the arm away from the middle line of the body and those are going to be abductor muscles there are also adductor muscles that are going to pull the limbs closer towards the midline of the body and then we're going to see circumduction which is going to be kind of a combination of flexion abduction extension and adduction all at the same time this is really just rotating one of your limbs in a cone of space let's look at some examples of this so you can see as this lady is demonstrating here if her arm is being pulled away from the midline of her body that's what we're going to call abduction like you're being abducted somebody's pulling you away versus adduction and that's when the arm is being pulled back towards the midline of the body again they're going to be muscles that are called abductor muscles and muscles that are called adductor muscles and they're doing these two different types of motion you can see if you're moving your arm or your leg in a cone of space this is what we're going to call circumduction kind of a 360 degree motion rotation you can think of as a instead of a 360 degree motion rotation is just a 180 degree so you can kind of rotate your head to the left you can rotate your head to the right but you could circumduct your head and spin it 360 degrees so we'll see this rotation is going to be done between the first and second cervical vertebrae remember the atlas sits on top of the axis and you can rotate that atlas on top of the axis this would be what you were doing if you're shaking your head no at somebody so here we can see the lady demonstrating rotation here in the neck by rotating her head left or rotating her head right there in that 180 degree range of motion you could do the same thing with the leg or the arm like i mentioned where you've got about 180 degree range of rotation there okay so now we're going to look at some of the special movements that are going to be accomplished by rotating the forearm and this is either going to cause that palm to face anteriorly if you're in anatomical position or if you rotate that forearm it'll cause the forearm to face posteriorly we know if we're in correct anatomical position those palms are facing forward or facing anteriorly so they're supinated rather than pronated here's what that looks like you can see uh pronated is where the palms are facing away from you posteriorly and then if the palms are facing anteriorly this is what we're going to call supernation other special movements include dorsiflexion and plantar flexion of the foot we're going to see that dorsiflexion is bending of the foot towards the shin this is simply when you take your toes and you bend them back towards the shin maybe think of pulling your foot off the gas this would be dorsiflexion versus plantar flexion where those toes are pointing down this would be stomping on the gas or stomping on the brakes your toes are going down again dorsiflexion you can see is pulling those toes up towards the shin and then plantar flexion would be planting those toes down would be stepping on the gas a couple of other special movements we can see inversion and e-version this is on prominent display if you're watching any of the basketball playoffs you see people kind of drive into the middle of the lane and they often will roll their ankle and it can occur in a couple of different fashions where they happen to roll their ankle where the the sole of the foot happens to face medially type of special movement that you see there is called eversion and that's where the soul actually faces out laterally here's what we're talking about uh again inversion would be if you were kind of balancing on the lateral side of your foot so that the bottom of the foot is facing immediately versus e version where you're balancing on the medial side of the foot and and the bottom of that foot is facing out laterally protraction and retraction we're going to see some examples here with the jaw but you can also see uh or think about this as examples with movements of the tongue for example if you stick your tongue out at somebody you're protracting your tongue or if you pull your tongue back into your mouth that's retracting the tongue this is kind of done with the jaw as well as this lady is trying to demonstrate by sticking her jaw out as far as she can in the first part of the picture by kind of protracting that jaw and then the second picture she's retracting it again maybe a better example if you think about sticking the tongue out or pulling the tongue back into the mouth the other example here is going to be elevation and depression you can do this with your shoulders right elevating your shoulders or depressing your shoulders but the picture is going to show us an example with the mandible once again so the lady here is uh in the picture on the right looking like she's just seen something really impressive and her jaw has dropped so that's depressing the jaw and then kind of closing her mouth back here would be elevating the jaw or elevating the mandible and now the last special movement which is opposition of the thumb and this is really just being able to touch your thumb to the tips of the other fingers on the same hand and this is what allows us to grasp onto things here we can see that opposition at least the index finger and the thumb have come together but again you can bring any of your fingertips over to touch the tip of the thumb now moving into classification of the synovial joints we just looked at different types of movements that the synovial joints are capable of so now we're going to look structurally at the different types of synovial joints how do they move what is their shape what are their different types of surfaces and we're going to see six different types of merge they're going to be examples that include plane joints we're going to see hinge joints pivot joints condyloid joints saddle joints and ball and socket joints this is the bottom part of the first page in your lecture handout where we have a series of matching questions that show us each of these different types of synovial joints first one we'll see here are going to be plane joints and these again are describing flat articular surfaces that are going to be able to glide past one another so we were talking about these different gliding movements earlier this is done by those plane joints those flat surfaces slipping past one another so you see a lot of that happening right here in the wrist second example are going to be these hinge joints and these are just going to move along a single plane so this is going to be something like your elbow these hinge joints that just do flexion and extension only when we look at their structure they tend to be a cylindrical shaped end of one bone and a trough shaped end of a second bone and you can see how they kind of fit together there's one cylindrical end and then one trough shaped in and they come together and form kind of a hinge and the elbow is a good example there third example is going to be of pivot joints and these are going to have a rounded end of one bone that conforms to the sleeve or a ring found on another bone we can see some examples here one is in the forearm the radius and the ulna are held together by this little ligament that is a sleeve and the the radius actually rotates around within that sleeve uh a second example that we've mentioned before even though it's not pictured here is that atlas and axis the first and second cervical vertebrae that atlas sits on top of the dens that process of the axis and rotates around that so that's another example of a pivot joint joints these are going to allow all different types of angular movements there are going to be two oval surfaces one happens to be in a kind of a cup shape and the other one happens to be in a little bit of a depression and they both fit together they're complementary surfaces you can kind of see that here one of them is kind of a rounded oval shape that kind of sticks out that bulges and the other one is kind of a oval shaped depression and together they allow all kind of different movements you can think of the fingers being attached to the metacarpals and you could point your finger and kind of wag it around in all kind of different directions that would be an example of one of these condyloid joints next example is of a saddle joint and these allow greater freedom than the movement that we saw in the condyloid joints an example of the saddle joints are going to be in your thumbs so when we look closely here there is going to be two surfaces that are complementary one is convex and the other one is concave one ends up looking kind of like a little saddle so hence the name saddle joint you can see these complementary shapes there the only example is going to be in the thumb and then that takes us to our ball and socket joint which is the most freely moving synovial joint and that means since it's the most freely moving it's going to be the least stable and most likely to pop out of place and suffer from dislocations and these joints we're going to see a rounded head of one bone fits into a cup like depression of a second bone here's a picture that we can think of the humerus as it fits into that glenoid cavity created by the scapula there another example even though it's not pictured here would be in the hip the head of the femur sits into that acetabulum of the hip bone so some common injuries that you see that happen uh where these two bones meet are going to be sprains and that's just where these ligaments get either stretched or torn depending on how bad the sprain is partial tears are going to repair themselves slowly but complete ruptures are going to require some type of surgical repair there is cartilage that we saw there and remember cartilage does not have direct blood supply so if cartilage does get damaged it rarely repairs itself and usually requires some type of surgery to get repaired we mentioned dislocations happen in joints and it turns out they're stable they are the less range of motion they have so the ones that have the greatest range of motion are the least stable like the ball and socket joints and can suffer from these dislocations so arthritis we're going to see comes in over a hundred different types and all types are some type of inflammatory or degenerative disease that are going to damage joints they end up causing these bones to grind together and that causes a lot of pain and swelling and stiffness in these joints they're going to be a couple of different forms we're going to see osteoarthritis and rheumatoid arthritis again both lead to these bones grinding together and causing a lot of pain and damage there but in osteoarthritis this is just going to be common wear and tear so over time these bones get worn down and degenerated and this normal wear and tear can result in that osteoarthritis rheumatoid arthritis on the other hand is going to be an autoimmune disease that is of unknown causes there's something that causes your your body's own immune system to go and attack the cells there uh found in those synovial joints and it erodes away some of the cartilage there and now there's uh bones that can directly grind together and that causes again a lot of damage a lot of swelling and a lot of pain here's an image of that you can see the tips of the fingers here there has been so much bone grinding together that there has been fusion between a few of those bones so this is somebody that has extensive rheumatoid arthritis so i think that does it for the joints powerpoint you'll notice again that uh the lab handout starts with muscles so there's no individual joints are going to be part of the lab so any of these examples uh from the class and out today or the powerpoints would be good to know for upcoming exams