Joints and Movement

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Joints and Movement

• Or
• Why doesnt my knee move from side to side like
  my head?
• (It doesnt, which is why we have Orthopedic
  Surgeons.)

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• A joint is a point of contact between two bones-
• A joint is also called an articulation. One bone
  articulates with another

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3 types of joints

• Classified according to the degree of movement-
  moveable, partially movable and no movement
• Arthr/o joint
• Diarthroses- moveable
• Amphiarthroses- partially moveable
• Synarthroses- immoveable

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Diarthroses joints

• Most of our joints are diarthroses-
• They tend to have the same basic structure-
  movable joints have 3 main parts
• Articular cartilage
• Joint capsule called a bursa
• Joint cavity called a synovial cavity

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• Bursa- a flatten sac filled with small amount of
  fluid. Found where muscle and tendon glide over
  bone. 100s throughout body

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• Enclosing two articular surfaces is an articular
  capsule, aka joint capsule made of tough fibrous
  connective tissue. Lined with synovial membrane,
  secretes synovial fluid into synovial capsule

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4 types of Diarthroses joints

• 1. Ball-and -Socket joints. Greatest movement. Ex
• Shoulders, hips
• 2. Hinge joints. Move in one direction or plane.
• Knees, Elbows, outer joints of fingers
• 3. Pivot joints.
• -Radius, ulna
• 4. Gliding Joints
• -Vertebrae

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• Ball and Socket

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• Hinge

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• Pivot

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• Gliding

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Just to review

• Diarthroses joints get all of the attention
• Amphiarthroses
• Ribs to spine, pubic symphysis
• Synarthroses
• Found in cranium, commonly called sutures

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Types of Motion

• Flexion- bringing two bones closer together,
  decreasing the angle between two bones
• Extension- increasing the angle between two
  bones. A straightening motion.

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• Abduction- movement of extremity away from the
  midline
• Adduction- movement towards the midline