Skeletal System 1a.4 PDF

[00:00:06] >> This overview of the skeletal system will start with a look at bone, looking at its structure, function and special bony landmarks. We'll then look at cartilage, also looking at the different types of cartilage and its role in the body. And finally, we will take an overview of arthrolo...

[00:00:06] >> This overview of the skeletal system will start with a look at bone, looking at its structure, function and special bony landmarks. We'll then look at cartilage, also looking at the different types of cartilage and its role in the body. And finally, we will take an overview of arthrology. [00:00:23] So talking about the different types of joints and the function of each of those joints. To take a quick overview of the skeletal system, we first want to clarify the difference between the axial skeleton, which includes things like the cranium, the vertebral colon, the ribs, and the sternum. [00:00:47] Which we will get into much more detail in the vertebrae shortly, and then the appendicular skeletal system, which includes bones that stretch towards the extremities, including the clavicle and scapula. And working your way out the extremities. Also included in the appendicular is the pelvis, as well as the femur and the rest of the lower extremity bones. [00:01:12] The function of bone serves a couple of different roles. Bone serves protection, especially things like this skull and the thoracic cage. Obviously bone also makes a lot of support, right? If we did not have bone our muscles would really just be a pile of mush. The bone also allows movement by creating levers and this you'll learn a lot more about in Movement Science. [00:01:37] Additionally on a physiological level. Bone stores salt for us, specifically calcium, and it contributes to the formation of blood cells. Finally, we will be considering different types of bone as we go through our study of anatomy. But in general, we look at bones such as long bones, right? [00:01:59] Things like the femur. Then there's also short bones, especially the carpals and the tarsals. There's also flat bones, for example, bones in the skull that are very flat. We have pneumatic bones, such as other bones in the skull like our sinuses. And we have sesamoid bones, obviously the most well-known of this would be your patella. [00:02:22] And there's accessory bones, which are just kind of extra bones that your body forms. And there's also heterotropic bones which are essentially pathological bone formation. As we journey through the study of anatomy we will encounter a lot of different bony landmarks. This slide just lists the names of many different types of bony landmarks, including things like a capitulate or a condyle, also things like a tuberosity or a tubercle. [00:02:55] These you'll start to recognize very specific ones as we go through different bones within each region. For example, on the humerus we will talk about tubercles and tuberosities. So for now just work to become familiar with, how does each of these bony landmarks present? What bony landmarks might be like a ridge versus ones that would be more of a bump. [00:03:25] As we wrap up our overview of bone, I want you to just take some time to ponder this question. We know that usually a bone fracture is going to be treated with some form of immobilization, either casting or a surgical fixation. So I posed the question to you what is the role of physical therapy after a fracture? [00:03:46] Feel free to take some time to pause the video and think about this, or just jot this down and reflect on it after we finished the rest of the content. We're going to take a brief look at cartilage in general here, but we will be talking much more about specific cartilage regions as we move through the body. [00:04:10] So first, we just want to recognize what the primary functions of cartilage are. One that we will talk about a lot that pertains to movement is its ability to absorb shock. Cartilage can also help to distribute loads. This is one of its major roles within our joints and cartilage in our joints can also really reduce friction. [00:04:35] So when we talk about articular cartilage, it's going to play all three of these lip rolls. Additionally, cartilage does contribute to the growth and development of bone. For example, the epiphyseal plates are made of hyaline cartilage. When we talk about cartilage, there are three different types of cartilage. We will talk a lot about hyaline cartilage. [00:05:00] This is where it's on the articular surfaces. This is also what creates the growth plates, and it's also what lines your respiratory passages, so for example, holding your trachea open. We will look at fibrocartilage as well, as this will come into play in certain joints. And it also plays some supportive and shock-absorbing structures. [00:05:25] Really key places that we will see fibrocartilage are in our intervertebral discs, as well as in the meniscus in our knees. And finally, there is elastic cartilage. As PTs, we don't deal with this as much because this is more of a general structural flexible cartilage. We will see this in places like the external ear and the nose. [00:05:50] So the structure of cartilage, Cartilage is a type of connective tissue. And so as a result, very similar to all the other connective tissues that we've talked about. It will have cells, it will have fibers, it will have an intracellular matrix. Now, one of the key things about cartilage is it does hold a lot of water, which is part of its shock absorbing ability. [00:06:18] Now, the other piece that goes along with that is cartilage does not have a good neurovascular supply. Now, why we care about neurovascular supply to different tissues is because the vascular supply is what brings nutrients, it's what enables healing. So what we will see is cartilage may have some challenges in healing. [00:06:42] Now, the other thing is, because of not having a distinct vascular supply, in order to get its nutrients, cartilage really depends on diffusion. And the way that happens is every time we compress cartilage, whether that's hyaline cartilage in your joints, or fibrocartilage in your discs, water will be squeezed out of the tissue. [00:07:04] When that load is removed, water will be pulled back in, and that is what allows nutrients to enter the cartilage. Cartilage also does not have a good nerve supply, so oftentimes pain associated with cartilage injuries is actually coming from the other structures that are being impacted. As we move through our study of the body, we will be learning about many different joints. [00:07:39] Joints in general will be classified into one of three structural categories. Fibrous joints are joints that are held directly together with a type of connective tissue. So these joints tend to not have a lot of movement. So for example, some fibrous joints are considered fixed. And these are called synarthroses right? [00:08:05] So syn means no. So these are no movement joints. And places that we see that are things like sutures. Those as you may recall from your previous anatomy courses are the essentially the joints between the bones in the skull which do not move at all, other fibrous joints may be slightly movable. [00:08:29] One that we will talk about one type of fibrous joint we'll talk about when we get to the arm and when we get to the lower extremity, our synarthroses. And this is where, two bones are held together with a band of connective tissue. We see this in the forearm between the radius and the ulna. [00:08:48] And we see it in the leg between the tibia and the fibula. So we will do much more detail as we get to those. Another interesting one that would be of interest to you if you went to dental school are what are called gomphoses. These are joints where essentially the bone is like a peg in a hole. [00:09:07] So when you think about your teeth in the bone of your jaw, there actually are ligaments, there's fibers that hold the tooth in, and that makes the connection between your tooth and jaw a gomphoses. Cartilaginous joints tend to fall into the slightly movable category. And there are two different types of cartilaginous joints, and what differentiates them is what type of cartilage is holding them together. [00:09:37] A symphysis joint places that we see that are like the pubic symphysis is where the two bones are held together with fibrocartilage. A synchondrosis, on the other hand, is where the bones are held together with hyaline cartilage. So the connection between your ribs and costal cartilage, that is a synchondrosis. [00:10:02] And finally, the joints we're really going to talk about a lot are our synovial joints, and that's because these are freely movable, which means they really contribute to our movement. So different types of synovial joints might be plain joints, where it's two surfaces, a hinge joint, where you have one degree of freedom. [00:10:26] There's also pivot, bichondylar, ellipsoid, seller and spheroidal. Spheroidal is a fancy word for our ball and socket joints. We will talk about all of these terms in much more detail as we get into each individual joint and analyze its structure. This image just provides some examples of the different types of synovial or movable joints that we have. [00:10:56] So we mentioned these on the previous slide. For example, a condyloid joint which is also sometimes called an ellipsoid joint really allows two degrees of motion. So you have a reasonable amount of motion but not as much as something like a ball and socket. A saddle joint, for example, we find this at our thumb this is what allows you to do so many different motions with your thumb. [00:11:23] That is what gives us as humans an opposable thumb. We will talk about much more detail when we do the hand. Another type of joint that we will be seeing as we start to talk about the vertebrae is a pivot joint. This is where there's essentially like a peg that can rotate. [00:11:41] So this is what allows, for example, your head to rotate on your upper vertebrae. So this is just some examples. You can refer to the textbook to look at these, but we will examine each in much more detail as we get to specific examples in our regional study.