Human Body: Why Do Knees Bend? (First Question and Answers Book 1)
Both lie in the middle of the capsule, together forming an X-shape, described by the term 'cruciate,' which means 'crossed. It's important to note that not all joints are synovial joints, so the specific orientation of ligaments varies. The functions, however, remain the same: Have any of your favorite athletes ever torn an ACL? Torn ligaments are common injuries for athletes. While the collagen that forms the ligaments is both strong and flexible, it does have limits.
Any abnormally strong force or awkward angle can stretch or tear a ligament. You can probably guess that it is important to allow these injuries to heal completely to avoid compromising the stability of the joint in question. Try bending and straightening your knees again. That's your ligaments in action! These fibers are usually arranged in parallel bundles and attached to the outer covering that surrounds all bones, the periosteum.
In a synovial joint , such as the knee, the bones, in this case, the femur and tibia, are separated by a joint cavity filled with fluid known as synovial fluid. In the knee, the medial collateral ligament MCL is located on the inside, or medial, surface of the knee, and the lateral collateral ligament LCL runs along the outside, or lateral, knee surface.
Intracapsular ligaments are located inside the articular capsule and include the anterior cruciate ligament ACL and the posterior cruciate ligament PCL. Both lie in the middle of the capsule, together forming an X-shape. To unlock this lesson you must be a Study.
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Not sure what college you want to attend yet? The videos on Study. Students in online learning conditions performed better than those receiving face-to-face instruction. Explore over 4, video courses. Find a degree that fits your goals. In this lesson, you will learn about the structure of ligaments and discover the very important role they play in the body.
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What Are Ligaments?
Add to Add to Add to. Want to watch this again later? What Is a Tendon? What Is Synovial Fluid? What Is Fascia in Anatomy? Pivot Joints in the Body: Holt McDougal Modern Biology: Angela Hartsock Angela has taught college Microbiology and has a doctoral degree in Microbiology.
Your bones are held together by ligaments. What Do Ligaments Do? Bones and ligaments form a sort of chain in your leg Ligaments can also prevent movement. The Structure of a Joint In order to understand the types of ligaments required for each function, we need to examine the structure of a joint.
The knee joint Extracapsular Ligaments Outside of the articular capsule are ligaments called extracapsular ligaments. Intracapsular Ligaments Some ligaments are located inside the articular capsule and are referred to as intracapsular ligaments. Try it risk-free No obligation, cancel anytime. Want to learn more? Select a subject to preview related courses: Lesson Summary Let's review. Functions of Ligaments Ligaments connect one bone to an adjacent bone They prevent damage and stress to joints through their strong fiber bundles Ligaments prevent joints from moving in the wrong direction They provide stability to joints Learning Outcomes When you are done, you should be able to: Explain what ligaments are and describe their functions Recall the structure of ligaments Describe the ligament structures of the knee.
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You are viewing lesson Lesson 13 in chapter 16 of the course:. Help and Review 20 chapters lessons. Inorganic Chemistry in Anatomy and Organic Molecules in Anatomy and Biochemistry in Anatomy and Basic Anatomy and Cell Biology The Nervous System at the Cellular Gross Anatomy of Muscular System Anatomy and Physiology of Male and Early Development to Childbirth Homeschool Curriculum High School Biology: The difference is that in humans, the feet have a hard time pointing down since they are never used as hands, and hands have a harder time pivoting to be perpendicular to the arm because they are never used as feet anymore.
Because of these behavioral differences from other great apes, variations that helped feet be used as hands and hands be used as feet were not selected for, but variations that reinforced walking and running ability and that reinforced object manipulation were selected for.
It's an amazing question, really. And you might be right about your assumption. In the womb, our legs and arms bent in the same direction. But as the foetus continued to develop, the legs and arms rotated to bend in opposite direction to each other. As of now, there is no rational explanation as to why this happens. So I guess all we can do is be grateful to the way our bodies have come into being. If, for instance, our knees bent backward just like our elbows , our legs would bend forward like our arms and we wouldn't be able to walk the way we do.
Your Muscles
Apply the same to the arms and we'd be lifting things in an entirely different way, and backwards too! Also, we won't be possessing the ability to write. You can check out this page for more info: By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service , privacy policy and cookie policy , and that your continued use of the website is subject to these policies. Home Questions Tags Users Unanswered.
Why are the human knees and elbows bent in an opposite direction Ask Question. Ronen Festinger 1 4. What research have you done on this so far?
Bones, Muscles, and Joints
I just found an article talking about god creation, this wasn't what I was looking for. And I still need to read about why human walk on two. Do you want to know evolutionarily why or developmentally why knees and elbows point in opposite directions? The latter question is more easily answered. Roland 5, 1 12 Do we have an ancestor having knees and elbows bending in the same direction?
Do they use similar metabolic pathway? What i meant was that i expcted the 4 limbs to be identical since they all were used for walking.
But I got already other good answers here that explained it. RonenFestinger Okay well then I guess you have your answer. You might also be interested in asking an engineering or mechanics question about it, as tetrapods walking robots often have front and back joints that are mirror opposites of each other.
You might also be interested in asking a question of why other animals have opposite front and back joints. What you should keep in mind is that although front and back legs are all used for walking, they don't have identical functions. Back legs might spring more, front legs might pull more and grab prey more. Irena 1 3 That's what I found too before asking this question. But I was looking for a different answer than god created it this way.
Well I'm sorry I couldn't be of much help, because there is no scientific theory to explain this as of now. You can always do research on it, though. See my answer for some basic information and pointers. When exactly are they bent the same way? For example, turtles in development start out with rib cages, like the reptiles they evolved from, and the rib cages fuse into a shell.