JOINTS

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JOINTS Articulations
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JOINTS Articulations

• Joints occur where 2 bones meet. They may
• join two bones with as little flexibility as
  possible
• join two bones with a little ' give'
• join two bones with a maximum flexibility

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JOINTS Articulations

• FIBROUS JOINT
• Ends of bones are separated by fibrous tissue vs.
  cartilage
• E.g. sutures of the skull (movement during
  birthing only), gomphosis (teeth in maxilla)?

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JOINTS Articulations

• CARTILAGINOUS JOINT
• cartilage sandwich with bone on either side
• bone and cartilage fit together perfectly and the
  whole thing is cup shaped
• E.g. sternoclavicular joint

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JOINTS Articulations

• SYNOVIAL JOINT
• Ends of bones move freely on each other
• Sliding surfaces are covered with a thin layer of
  articular cartilage (coefficient of friction
  lt0.002) E.g. knee joint

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Classification of Joints

• Complexity
• Simple - 2 articular surfaces (1 male 1 female)
  
• Compound (elbow joint humerus ulna / humerus
  radius / ulna radius)

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Classification of Joints

• Degrees of Movement (freedom)?
• Uniaxial - joint which moves substantially in one
  plane (like an elbow)?
• Biaxial - moves in two planes
• Triaxial - moves in three planes
• A ball and socket is multiaxial, but is
  equivalent to a triaxial as it has three degrees
  of freedom

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Classification of Joints

• Shape - probably the most widely used
  classification
• 1.hinge joints permit flexion and extension
  (knee)
• 2.pivot joints allow rotation (superior
  radio-ulnar)?
• 3.gliding or plane joints have flat surfaces
  and allow gliding in several directions (carpus
  and tarsus)

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Classification of Joints

• condylar joints usually regarded as two hinge
  joints with separate articulations (TMJ)
• saddle joints have surfaces shaped like two
  saddles - allow movement in two planes at right
  angles and a little rotation (base of thumb)
• ball and socket allows very free movement around
  any axis through ball (hip)
• ellipsoid ball and sockets which are not round
  rotation therefore impossible (radiocarpal joint)

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Classification by function

• Movements at two bone ends are made up of1.
  gliding of one surface over another - slide 2.
  angulation of one surface over another roll
• 3. rotation about bone axis - spin

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Synovial JointsRelated Structures

• Ligaments
• strong connective tissues that run from bone to
  bone help maintain stability in a joint
• not elastic can lose their ability to perform
  correctly when over stretched/torn
• collateral attach on medial lateral aspects
  of bones to provide support

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Synovial JointsRelated Structures

• Fibrocartilage
• occupies the space between certain bones to form
  the articular surface
• can take on many sizes shapes
• may be round/disk-like (IVD TMJ) or
  flat/circular (meniscus) or exist as a lip or
  edge to deepen a joint (GH labrum)?
• resilient functions as a shock absorber
• avascular relies on synovial fluid for
  nourishment can suffer injury (tears)

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Synovial JointsRelated Structures

• Synovial Membrane
• thin tissue surrounding most freely moving
  joints
• membrane secretes synovial fluid which provides
  nourishment for cartilaginous disks, lubrication,
  and hydrostatic cushioning

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Synovial JointsRelated Structures

• Joint Capsule
• tough fibrous sheet that surrounds many joints
  functions to protect them and provide stability

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Synovial JointsRelated Structures

• Bursae
• liquid-filled membranes that protect soft tissues
  as they pass by bony projections (eg. subacromial
  bursa of shoulder)?

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Synovial JointsRelated Structures

• Fat pads
• literally, small pads of fat tissue to fill in
  gaps between bones cushion bones

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Synovial Joints
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Synovial Joints-Tibiofemoral
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Synovial Joints-Iliofemoral
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Synovial Joints-Shoulder Complex
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Synovial JointsInjuries- Osteoarthritis
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Synovial JointsInjuries- GH Subluxation-
Dislocation
Clavicle
Glenoid fossa
Scapula
Humeral Head
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Synovial JointsInjuries-OUCH
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Synovial JointsInjuries-HELP
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Rotator Cuff and Anatomy Pathology