[Music] hey guys in this lesson I'm going to be teaching you about the gross anatomy of a bone including all the standard structures you'll find with a brief explanation of their function so bone gross anatomy and the first thing to point out is that bones are made up of several different tissue types which uh would classify them as an organ as we uh learned in the levels of structural organization video so they're classified as organs because they have several tissue types starting with the uh overall appearance of a bone we're going to notice here that we've got a one end up the top a long thin portion in the middle and a Stumpy kind of end at the bottom as well and this is a a long bone so we've got the top the middle and the base and these all have specific names now the top portion here is what we call the proximal epiphysis it's called the proximal epiphysis because it's closest to the uh attachment point of the trunk at the the other end we have the distal epiphysis and they are named relative to their position and we'll start to make a habit from now on of using the correct directional terms so we can get used to it I'll just point out uh that also it's going to be helpful to know that this bone is the humoris which is a bone in the upper half of your arm so the proximal is going to be at the shoulder end and the distal end of the bone is going to are down towards your elbow leading towards your hand now our epiphyses are going to contain a unique type of bone called spongy bone uh you might also hear it called woven or cancellus bone and they are going to be the interaction points for where the bone meets the surface of another bone now this leads to that area needing to have some form of protection for a for movement and for resisting shock and that comes in the form of Highland curtilage or articular curtilage that we've spoken about before but what about this middle portion of the bone we see over here well that's going to be known as the diaphysis the diaphysis is the long axis of the bone and it's going to have a central cavity within it because the diaphysis is much thinner than the epiphyses it's also going to be uh needed to be made out of something much stronger and that's called compact bone the compact bone has a much denser structure and can support more weight than the woven bone so we have learned so far that we have the two ends of the bone and a middle but there is even going to be a name for this portion that separates the two and it's called an epipal plate despite its small size actually has a very important function the epipal plate is going to be made out of a disc of Highland curtilage that will constantly grow and push new condra sites down into the diaphysis where they will Aid in the growth and elongation of the bones so it's pushing it down toward the diaphyses and that's going to be happening at the uh at the distal epiphysis as well that same thing will be happening at that PL it is not until early adulthood where these plates will fuse and transform into bone themselves uh thus controlling the height at which we will uh Reach In Our Lifetime so fuses in adulthood now the next thing I'm going to outline here is what we call the periosteum now the periosteum is a membrane covering that goes all around the bone and actually the only part of the bone that isn't covered in this periosteum are the articular cartilage points at the ends so it's a membrane it's going to go all the way around the bone covers the whole bone so I'll just color in that section of the bone there so you can see that it's going all the way around but we have another type of fiber in here that's going to be attaching that membrane onto the bone surface and we call those fibers Sharpies fibers or perating fibers the Perforating fibers are going to connect the periostium to the Bone and they're made out of very strong collagen fiber so we've got those two layers of periostium and perating fibers and they're both types of connective tissue so let's quickly recap what we've learned so far we've learned that there are two ends of the bone called the epiphyses there's a middle portion called the diaphysis it's going to have a central cavity and there's going to be those epipal plates where the growth and elongation is going to happen but from there what's our next kind of thing well like I said that bone is an organ so we're going to need to keep it alive and keep the cell in the bone alive as well and we do that with nutrient arteries so those arteries that are going to be uh going into the bone and Perforating the surface of the bone are going to be delivering blood to the Bone so so you can grow new tissue and store nutrients and uh as I highlighted when we uh spoke about the diaphysis I'll just quickly uh right in here and show you a closeup of the compact bone the compact bone is much denser as I said before and it's going to be made out of long units of bone called osteons or hervs systems and the herion systems are quite complex and we'll we'll talk about the herion system in in a later video so it's made out of osteons and you can see them I'm just circling them here long units that stretch along the length of the bone so there your osteons so I've said that we we have this middle portion that's a central cavity in the diaphysis and I'm just outlining this uh structure that we see in the middle here because it's going to be the next thing that we'll look at there's absolutely no point in having empty space in the body so we use those Central cavities of the bone to store or yellow bone marrow yellow bone marrow is mostly just fat tissue so it's stored nutrients there we go so stores of fat and another name for that Central cavity is the medary cavity so if you hear the term meary cavity they're talking about that space in between the diaphyses of our long bones and just the last thing I will highlight here on the central portion of our long bone within the diaphysis is what we call the ostium so we've got the periostium on the outside which is that membrane and the inner surface is called the endium now it doesn't have a it doesn't have a a membrane there but we just call it the endium so we know that's the name for the surface area of that inner cavity okay we're getting very close to the end now one of the last things I'll highlight up here is the fact that I spoke about spongy bone earlier but I didn't really point it out so we've got the spongy bone and it looks like it's woven all together so that's why you'll see it called woven bone as well so it's Loosely connected bone tissue but it's still also quite strong and it's going to be one of the main sites of hematopoesis and hematopoesis is where we uh grow and uh develop and mature our blood cells so that's going to be happening in those those end epiphyses of the lung bones within that spongy bone we can see all these holes it's all woven together with uh with empty spaces all throughout we call those thin filaments of the that line this area the tulle so we'll write that down here tulle now in between those spaces of the tabula is going to be the area where we keep that red bone marrow which will be the sight of hematopoesis so we have the yellow bone marrow storing our fat tissue in the meary cavity and our red bone marrow having a role in proliferation of new uh blood cells now before I get too far ahead of myself I'll just point out that down the bottom here we can see that articular cartilage on the end of the bone and also on the top of the bone I'll just highlight here too so that's the surfaces that our articular cartilages are going to be and that's our gross anatomy of the uh bones guys as always I hope it was helpful and I'll see you next time