okay so in this video over look at the cartilaginous joints and remember we talked about how there are three structural classifications of joints that we had fibrous cartilaginous and synovial now for the fibrous joints we said we had our composes syndesmosis and our sutures but with a cartilaginous joints their bones united by cartilage not fibers tissue so like the fibrous joints though they don't have a joint cavity so basically just find cartilage between the two bones there's no cavity there and again these are also not highly moveable some of these are going to be amphiaraus rhotic and Cinar throught ik but not diarthrotic so the two types of cartilaginous joints are the synchondrosis and the syntheses a synchondrosis is a joint that's united by hyaline cartilage and a symphysis is a joint united by fiber cartilage but we don't have joints that are united by elastic cartilage so for the synchondrosis it's a bar or play-doh hyaline cartilage that unites those bones or connects them almost all of these are Cinar throught ik even though Highland cartilage is slightly movable and you know kind of stretchable technically the place where the book two bones meet is going to be Sonora throught ik but that doesn't mean the cartilage itself can't expand it's just that where the cartilage meets the bone it's been not going to move a whole lot so examples of synchondrosis would be like the epiphyseal plates so remember your growth plate between the epiphysis and diaphysis of your long bones these are technically a synchondrosis because you have a place where there's epiphyseal cartilage right the Highland cartilage that's separating two bones so that what's cool then is your epiphyseal plate or growth plate is technically a joint now you also find hyaline cartilage comprising the costal cartilages of your ribs so technically where the rib meets the sternum that's going to be a synchondrosis which is a Highland cartilage joint it's an example this is like where the first rib meets the manubrium of your sternum but you know other ribs as well are gonna have hyaline cartilage except for the floating ribs I don't have they don't have cartilage so two examples here remember we talked about the epiphyseal plate which is your growth plate technically this is a joint because you're separating two bones and they're united by a plate of hyaline cartilage which makes it a synchondrosis now we're the ribs meat the sternum they're gonna be connected by a little bit of hyaline cartilage here so it's a borrow Milan cartilage and so this is also technically a synchondrosis now this makes sense with respect to the thoracic cavity because highly cartilage is kind of stretchable so this is gonna allow for some degree of stretch of your thoracic cage during ventilation or breathing now the syntheses are joints that are united by fibrocartilage we've talked about once synthesis already back in bones and that was the pubic symphysis right and this so technically the pubic symphysis is going to be a little bit of fibrocartilage there now you might also find some heiling cartilage comprising the articular surfaces of those bones but you will find fibrocartilage you know in the middle of those joints now syntheses are strong because fiber cartilage has lots of collagen fibers but these are gonna be in fair radicand slightly movable so it would make sense then to have syntheses at like the pubic symphysis which unites the two halves of your pelvis or even the intervertebral joints that way there's some degree of movability of your spine so if we look at the symphysis joint of our spine here we say that in the lumbar region what separates these two vertebrae then is a plate of fibrocartilage now we still have articular cartilage at the ends of these bones but in the middle of this joint we find a nice big plate of fiber cartilage and this allows for a degree of move ability here at the spine so each individual intervertebral joint of your spine can move a little bit which means the whole spine can move quite a bit now that's an example of a symphysis joint because it's made by fiber cartilage now another example of the symphysis is the pubic symphysis here which unites the two halves of your pelvis so this is one Hass set this is another oz set and each one is made of three different bones we have the ilium the ischium and the pubis but you know each half of the of the hoxsey here which make up the pelvic girdle they're united anteriorly by this pubic symphysis so which kind of odd here then is right in the anterior part of the pelvic girdle you find a little bit of fibrocartilage now the function of this is to for a little bit of wobble of your your pelvic girdle that way when you're walking it's kind of cushioned and these are some degree of move ability here that we don't walk so rigidly and also this pubic symphysis can relax during labor that way the two halves of the pelvis can separate which opens up the pelvic outlet which makes it easier for birth to occur in fact there's a hormone called relaxin that makes this cartilage a little bit weaker and that way these bones can separate more now the joint doesn't break it's just that this cartilage is a little more loose so it's more stretchable