Joints

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Joints

• Chapter 9

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Articulations or Joints

• Region where two bones meet and allow some degree
  of movement between the bones.
• Structural Classes
• Bony Joints
• An immobile joint formed when the gap between two
  bones ossifies and they become essentially one
  bone.
• Fibrous Joints
• Articulating bones are held together by fibrous
  connective tissue. Lack joint cavities.
• Cartilaginous Joints
• Articulating bones are held together by
  cartilage. Lack joint cavities.
• Synovial Joints
• Articulating bones are capped with cartilage and
  ligaments are involved in support of the two
  bones. Possess fluid-filled joint cavities.

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Fibrous Joints

• Sutures
• Thin layer of dense irregular connective tissue
  binds the articulating bones.
• Skull only, little or no movement.
• Gomphoses
• Root of tooth attached to periodontal ligament of
  dental alveolus.
• Tooth and jaw, little or no movement.
• Syndesmoses
• Collagenous fibers or sheets of fibrous tissue
  hold bones together.
• Distal radius and ulna, slight movement.

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Cartilaginous Joints

• Synchondroses
• Bones separated by hyaline cartilage.
• Epiphyseal plates, costochondral articulations,
  no movement.
• Symphyses
• Bones separated by fibrocartilage.
• Symphysis pubis and intervertebral joints,
  limited movement.

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Synovial Joint Structure

• Joint capsule
• Dense regular connective tissue.
• Lined by synovial membrane that secretes synovial
  fluid.
• Synovial fluid cleans and lubricates joint.
• Articular cartilage
• Ligaments bind bone-to-bone.
• Tendons bind muscle-to-bone.
• Meniscus (not shown)
• Fibrocartilage
• Cushion and guide articulating bones.
• Bursa (not shown)
• Closed connective tissue sacs contain synovial
  fluid.
• Between bone and muscle or tendon and bone
• Cushion between bone and muscle or tendon.

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Kinds of Synovial Joints
Multiaxial movementgreatest range of movement
Movement in one plane
Intercarpal joints slide in all
directionslimited movement
Rotational movement
Wide range of movement, circular and linear
Angular movement in two planes
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Movements at Synovial Joints

• Angular
• Flexion
• Decreases the joint angle on an anteroposterior
  plane.
• Extension
• Increases the joint angle on an anteroposterior
  plane.
• Hyperextension
• Extension beyond anatomical position.
• Abduction
• Movement of a body part away from midsagittal.
• Adduction
• Movement of a body part toward midsagittal.

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Movements at Synovial Joints

• Circular Movements
• Rotation
• Movement around a body parts axis
• Circumduction
• Movement of an extremity such that the extremity
  traces an cone-shaped airspace.

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Movements at Synovial Joints

• Special Movements
• Protraction
• Movement of a body part anteriorly, parallel to
  the ground.
• Retraction
• Pulling a body part posteriorly, parallel to the
  ground.
• Elevation
• Raises a body part
• Depression
• Lowers a body part

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Joint MovementMore Practice
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Joint MovementMore Practice