in one of our previous videos we look at the periodontium and we said the periodontium is made up of four things okay so we're looking at the periodontium it's made up of four things or four structures or um yeah four structures and um the way i can remember it there's different mnemonics i'm gonna use gpac as a mnemonic so look at it and around the tooth we see four things that are surrounding that toot first thing we see is the gums okay so gingiva the other thing we see is a periodontal ligament fibers so these blue lines that we see running across that is your periodontal ligament fibers another thing we see is the yellow which is the bone so we see the alveolar bone so a for alveolar bone and then we also see the cementum and cementum is i'll draw it in so that we can see it's momentum covers the roots we'll see if i can probably draw it down um cementum is the layer that is just covering the root okay so cementum is covering the entire root now one of the things i want to focus on for this video is your periodontal ligament fibers so periodontal ligament fibers um the short way of saying this is p for periodontal uh for periosteal defordonto and l for ligament now periodontal ligaments have fibers which are those blue lines that we see running across now there's many different periodontal ligament fibers and we're going to look at the different ones so one thing i want to note or i want you guys to know is that when we're looking at the bone okay so here the yellow thing that we're looking at is the bone the very top of the bone the very crust or the very tip of it is known as your crust crustal bone okay crustal bone because it's the tip of the bone is known as your alveolar crust and so naturally if you were to look at i'm going to draw this in blue so that we can see it better if you were to look at this fiber over here that's connecting the alveolar crest tute that is naturally known as your alveolar crest fibers because if you look at its location it's um connecting from the toot to the alveolar crust which is the tip of the bone there's another fiber that runs like this horizontally and so because it runs horizontally that is known as your horizontal fibers okay let's look at some other fibers if you look at this one over here do you see how it's kind of um slanted it's running in an oblique fashion or a diagonal fashion when you have um periodontal fibers running in an oblique fashion like so it is known as your oblique fibers it's so hard to write on a computer okay can you guys guess what this type of fiber would be called when it's at the apex of the root apex of the root if you guess apical fibers you are correct so when you have fibers that are running from the apex of the root to the bone it is known as apical fibers and then what about this one over here what is when you have fibers that are in between roots [Music] draw an arrow it is known as inter so enter means in between i'm interredicular into radicular fibers so we just looked at one two three four five five different fibers and all these fibers are periodontal ligament fibers so they're all there that's holding and it's holding the tooth in its spot without those those fibers the tooth will just pop out so we need fibers to keep our teeth um you know in place and there's many other reasons too which will look at different sections of the video but one thing i want you guys to know is periodontal ligament fibers have bi principle fiber groups