Transcript of How are bones held together?
How are bones held together? Bones are held together by joints, muscles, tendons, and ligaments. Ligaments - a tough band of tissue that holds the ends of bones together at a joint Joints - where two or more bones meet together Tendons - cords of connective tissue that attach muscle to bone Muscles and tendons attach to bones on either side of a joint, holding the bone(s) together tightly In the human body, there are about 400 joints. This diagram shows the side view of the knee. In it, you can see where the bones are and how they are connected. There is cartilage, but also ligaments connecting the two bones together. And tendons connecting the bone to the muscle. . . but you cant really see that. What kind of joints are there??? There are 6 main types of joints: Ball and socket, hinge, gliding, saddle, pivot, and fixed joints. A ball and socket joint, is formed when the round head of one bone fits into the cavity of another, as shown in the diagram. A hinge joint, provides a flexing and extension movement, like how a door hinge works. A gliding joint is formed when a flat, or slightly flat, surface of two bones glide along each other A saddle joint is formed when the surfaces of both bones joined have a concave and a convex region A pivot joint is formed when the round part of a bone fits into a ring formed by a tendon at the other bone Fixed joint, are joints in the skull that do not move at all. Bill Nye??? Without the tendons and ligaments in our body, we would basically just have bones floating throughout our bodies, and have no support to stand or do any of the things we do today. "I NEED SOME LIGAMENTS!" Without muscles, we would not be able to do anything...even with all of the joints connecting our bones to form one body (us) we need muscles in order to function. We have three different types of muscle in our bodies One kind of muscle we have is called Skeletal muscle. It is attached to bone, mostly in our legs, arms, stomach, chest, neck, and face. Skeletal muscles are also at times called striated (stry-ay-ted) because they are made up of horizontal striped fibers when viewed under a microscope. These muscles hold the skeleton together, give us shape, and help us with everyday movements (can also be called voluntary muscles because you can control their movement). They can contract (shorten or tighten) quickly and tire easily and have to rest between workouts. Another type of muscle is Involuntary muscle. It is also made of fibers, but looks smooth. We can't consciously control our smooth muscles, they're actually controlled by the nervous system automatically (hence the reason the are called involuntary). Smooth muscles can be found in the walls of the stomach and intestines, and also can help break up food and move it through the digestive system. Smooth muscle is also inside of blood vessels, where it squeezes the stream of blood flowing through the vessels to help maintain blood pressure. Smooth muscles take longer to contract than skeletal muscles do, but they dont tire as easily. The last kind of muscle is Cardiac muscle, in the heart. The walls of the heart's chambers are almost entirely made of muscle fibers. (Its an involuntary muscle) Its contractions force blood in and out of the heart as it beats. . .letting us live (duhh) So what else holds bones together????????? REVIEW: Bones are connected to other bones by ligaments, and bones are connected to muscles by tendons. Tendons are strong, built from long strands of protein, and are not very stretchy. When a muscle pulls, they pull too and can move our bones. We have tendons in many parts of our bodies: wrists, elbows, thumbs, shoulders, knees, head, legs, and heels. Tendons not only connect bone to muscle, but sometimes they connect muscle to other things. . . Like our eyes!!!!! Did you know that you can find at least one tendon in your body pretty easily? It's called the Achilles tendon that connects your calf muscles to your heel. When you're sitting, lightly pinch the back of your leg, right above your heel. Wave your foot, like it was your hand. You'll feel something moving in the back of your leg. What is it? A bone? Nope! It's a tendon!!!!! Ligaments are stretchy bands of tissue that hold one bone to another. They are what allows most joints to move, help control their motion, and stabilize them so that the bones move in proper alignment. Proteins known as collagen make up the tissue in most ligaments. Proteins known as 'collagen' make up the tissue in most ligaments. Collagen fibers are found throughout the bodies of humans, help the skin stay elastic, and also make up most types of connective tissue. The placement of these fibers allows them to stretch significantly when they move, such as when the elbow is bent or straightened. Collagen fibers are often arranged in crossing patterns, which helps prevent the joint from moving past its normal range of motion despite the ligament's flexibility. Connective tissues are in our bodies mostly to protect organs, store energy, support body structures, or connect other tissues. Other ligaments, such as those found in the back, mainly provide stability to bone or cartilage. If the structure primarily strengthens or supports other ligaments, it is called an accessory ligament. So. . .what would happen if we didn't have ligaments??? Well, one...it would be extremely painful to walk of do anything with out bodies, and we'd constantly have bone rubbing against bone..which would, in time, wear the bone down.. And two, ligaments hold our bones together, with muscles and tendons yes, but without ligaments we'd have no support in our bodies and we'd have to have someone help us do everything. The End!Full transcript