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Joints

Joints

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This lesson will introduce the three types of joints in the human body and will give examples of each type.

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Tutorial

What's Covered

In this lesson the types and structure of joints in the body.

  1. Types of Joints
  2. Synovial Joints

1. Types of Joints

Joints are areas of contacts between bones in your body. You have many different joints that connect bones within your body, and ligaments, a type of dense connective tissue, that connects the bones at those joints. Ligaments help to stabilize the joints as well. Tendons are the connective tissue that holds your muscles to your bones

Terms to Know

    • Joint
    • a structure that is formed by two or more bones joining together; are held together by ligaments, cartilage, or dense-fibrous tissue
    • Ligament
    • a structure composed of dense irregular connective tissue that holds bones together within synovial joints
    • Tendon
    • A tough band of fibrous connective tissue that usually connects muscle to bone.

There are three types of joints in your body:

  • Synovial joints- the most common type of joint in your body. They contain a cavity that's filled with a fluid called synovial fluid that separates the bones, and allow for a wide range of motion

ExampleThe knee joint- You're able to flex and extend your knee, and this type of joint allows for that motion.

  • Fibrous joint- in a fibrous joint there is no cavity between the bones. The bones are connected by a connective tissue that doesn't allow for very much movement

ExampleYour skull- made up of over a dozen type of bones but those bones are connected by fibrous joints called sutures.

  • Cartilaginous joints- type of joint where cartilage will fill the space between bones. So you don't have as much movement as you would in a synovial joint, but there is slight movement.

ExampleThe bones of the spine- in between each of those we have these little pads of cartilage. It eliminates some of the friction between the bones, but also allows for a slight bit of movement.

Terms to Know

    • Synovial joint
    • the most common joint in humans and also the most complex; contains two key characteristics: surrounded by a joint capsule and contains synovial fluid; also the most highly moveable joint in humans
    • Synovial fluid
    • fluid found within synovial joints to reduce wear and tear and to nourish the structures inside of the joint capsule
    • Cartilaginous joint
    • a joint where two or more bones are held together by a piece of cartilage (example: vertebrae or pubic bones); these joints are slightly moveable
    • Fibrous joint
    • a joint where two or more bones are fused together by tough, fibrous connective tissue (example: skull sutures); this is the least moveable joint of the body

2. Synovial Joints

Let’s take a look at synovial joints a little bit more in depth. This type of joint allows for a wide range of motion. The different types of motion are:

  • Flexion and extension
  • Rotation
  • Circumduction
  • Supination and Pronation
  • Gliding
  • Abduction and adduction

Imagine all the different ways in which you can move your arm and wrists. Now let's describe what these movements are:

Flexion and extension are the motions made when bending and straightening. Flexion happen when you flex a muscle to bend a joint. Extension happens when you relax the muscle and let the joint straighten.

Terms to Know

    • Flexion
    • A type of movement allowed primarily by synovial joints in which an appendage is able to bend. For example, flexion of the bicep muscle pulls the forearm upward by allowing it to bend at the elbow.
    • Extension
    • A type of movement allowed primarily by synovial joints in which an appendage is straightened from a flexed position. For example, extension of the arm from a flexed position will return it to its normal resting position.

Rotation can occur at synovial joints. To get an example of this type of movement, hold your arm straight out and twist it around it’s axis. Circumduction happens when an appendage moves in a circular motion. If you do an arm circle, this is an example of circumduction.

Terms to Know

  • Rotation
  • A type of movement allowed primarily by synovial joints in which an appendage pivots about its axis. Holding the arm straight out and twisting it on its axis is an example of rotation.
  • Circumduction
  • A type of movement allowed primarily by synovial joints in which an appendage moves in a circular motion. Doing arm circles in which the arm moves in a large circular pattern like a windmill is an example of circumduction.

Pronation and supination can be demonstrated by your hands and forearm. When you turn your palm and forearm to face upwards, this is supination. When you turn them to face down, this is pronation. The joint in your wrist also allows for gliding. You can wave your hand back and forth as the joints in your wrist allow for this gliding motion.

Terms to Know

    • Pronation
    • A type of movement allowed primarily by synovial joints in which the forearm and palm face downward.
    • Supination
    • A type of movement allowed primarily by synovial joints in which the forearm and palm face upward.

Abduction and adduction are also possible. If you lift your arm straight up away from your center, you would be abducting it. If you lower it back down to your side you would be adducting it.

Terms to Know

    • Abduction
    • A type of movement allowed primarily by synovial joints in which an appendage is moved away from the body’s center. Lifting your arm up and away from your side is an example of abduction.
    • Adduction
    • A type of movement allowed primarily by synovial joints in which an appendage moves closer to the body’s center. Lowering your arm closer to your side from a lifted position is an example of adduction.

Summary

The contact points between your bones are called joints. There are three main types of joints in your body: Synovial, cartilaginous, and Fibrous joints. The Synovial joint allows for the widest range of motion

Keep up the learning and have a great day!

Source: THIS WORK IS ADAPTED FROM SOPHIA AUTHOR AMANDA SODERLIND

TERMS TO KNOW
  • Joint

    A structure that is formed by two or more bones joining together; are held together by ligaments, cartilage, or dense-fibrous tissue.

  • Synovial joint

    The most common joint in humans and also the most complex; contains two key characteristics: surrounded by a joint capsule and contains synovial fluid; also the most highly moveable joint in humans.

  • Synovial fluid

    Fluid found within synovial joints to reduce wear and tear and to nourish the structures inside of the joint capsule.

  • Cartilaginous joint

    A joint where two or more bones are held together by a piece of cartilage (example: vertebrae or pubic bones); these joints are slightly moveable.

  • Fibrous joint

    A joint where two or more bones are fused together by tough, fibrous connective tissue (example: skull sutures); this is the least moveable joint of the body.

  • Ligament

    A structure composed of dense irregular connective tissue that holds bones together within synovial joints.

  • Flexion

    A type of movement allowed primarily by synovial joints in which an appendage is able to bend. For example, flexion of the bicep muscle pulls the forearm upward by allowing it to bend at the elbow.

  • Extension

    A type of movement allowed primarily by synovial joints in which an appendage is straightened from a flexed position. For example, extension of the arm from a flexed position will return it to its normal resting position.

  • Abduction

    A type of movement allowed primarily by synovial joints in which an appendage is moved away from the body’s center. Lifting your arm up and away from your side is an example of abduction.

  • Adduction

    A type of movement allowed primarily by synovial joints in which an appendage moves closer to the body’s center. Lowering your arm closer to your side from a lifted position is an example of adduction.

  • Rotation

    A type of movement allowed primarily by synovial joints in which an appendage pivots about its axis. Holding the arm straight out and twisting it on its axis is an example of rotation.

  • Circumduction

    A type of movement allowed primarily by synovial joints in which an appendage moves in a circular motion. Doing arm circles in which the arm moves in a large circular pattern like a windmill is an example of circumduction.

  • Pronation

    A type of movement allowed primarily by synovial joints in which the forearm and palm face downward.

  • Supination

    A type of movement allowed primarily by synovial joints in which the forearm and palm face upward.

  • Tendon

    A tough band of fibrous connective tissue that usually connects muscle to bone.