Key Points Of Joints

  • Created by: Catherine
  • Created on: 13-10-15 20:30
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  • Joints:  An articulation or joint is a place of union between two or more bones regardless of the degree of movement allowed by the union
    • Synarthroses: Don't allow movement
      • Suture: a joint in which the bones are joined together by a thin layer of fibrous connective tissue, like sutures of the skull
      • Syndesmosis: bones are connected by the ligaments between the bones e.g the Radius and Ulna bones
      • Gomphosis: conical process in a socket held together by ligaments like a tooth in a socket
    • Amphiarthroses:  only allow for slight movement
      • Symphysis: the bones are joined by a disk of fibrocartilage, as in the pubic symphysis
      • A synchondrosis: a joint where two bony surfaces are joined by hyaline cartilage, like the growth plate between the diaphysis and epiphysis of a long bone. Some people may classify this as a synarthroses
    • Diarthroses /Synovial : freely moving joints
      • Characterized by having  capsular structure with an internal cavity
      • The capsule joint can be made up of many different kinds of tissue
        • Fibrous cartilage
        • Ligaments
        • Tendons
        • Muscle
        • Synovial membranes
      • Diarthroses/ Synovial joints have different functions
        • They bear weight and allow movement
        • The ligaments, tendons, muscles and articular cartilage provide stability
        • The Synovial fluid lubricates surfaces and nourishes the cartilage
    • Movements at Synovial Joints
      • Flexion: decreases the angle between bones
      • Extension: increases the angle between bones
      • Hyperextension: increases the joint angle beyond the anatomic position
      • Dorisflexion: raises the foot upward the ankle joint
      • Plantar Extension: pushes the foot down at the ankle joint
      • Abduction: moves a bone away from the midline
      • Adduction: moves a bone toward the midline
      • Rotation: moves a bone around a central axis, perpendicular to the axis
      • Circumduction: moves a bone so the end of it describes a circle and the sides of it describe a cone
      • Supination: moves the palm of the hand to an upright position or from a posterior to an anterior position if at the side of the body
      • Pronation: moves the palm of the hand to a downward position or an anterior position to a posterior position if at the side of the body
      • Eversion : moves the sole of the foot outward at the ankle
      • Inversion : moves the sole of the foot inward at the ankle
      • Protraction: moves a part of the body backward on a plane parallel to the ground
      • Retraction: moves a part of the body backward on a plane parallel to the ground
      • Elevation: raises a part of the body
      • Depression: lowers a part of the body
      • Opposition: unique to the thumb, allows the tip of the thumb and fingers to be brought together
      • Reposition: opposite of opposition
    • Six types of diarthroses or synovial joints
      • The Ball and Socket Joint ( multiaxial ) allows movement, as in the shoulder or hip joint
      • The Hinge Joint ( uniaxil ) limits movement to flexion and extension, examples are the knee, elbow, and the middle and distal phalanges of the fingers and toes
      • The Pivot Joint ( Uniaxil ) limits movement to rotation in one plane, such as the atlas and axis articulation in the spine
      • The Condyloid joint or ellipsoidal ( biaxial ) joint allows movement in two planes at right angles to one another, located at the carpal- metacarpal articulation in the thumb
      • The gliding Joint ( multiaxial ) allows only gliding motion, as the intervertebral joints in the spine
      • The Saddle joint ( biaxial ) found only in the thumb, allows movement in two places at right angles to one another, located at the carpal- metacarpal articulation in the thumb
    • Bursae: closed sacs with synovial membrane lining that prevents friction between overlapping tissues
      • Subcutaneous : found within the skin and underlying bony processes
      • Subfascial: found where muscles overlie each other
      • Subtendinous : found where one tendon overlies another or overlies a bony projection


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