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Scapulothoracic Joint

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Topic updated on 08/04/14 4:58pm
                                              
Introduction
  • Function
    • allows scapular motion against the rib cage
  • Osteology
    • not a true joint; actually an articulation between the scapula and the thorax 
    • is a sliding "joint" between medial border of scapula and ribs 2-7
    • resting position angulation (although these are variable even in healthy adults)
      • anteriorly 10-20°
      • internally rotated 30°-45° from the coronal plane 
      • upward tilt of 3°
Biomechanics
  • Motion 
    • primary motion  
      • elevation & depression
        • movement up and down along the rib cage
    • secondary motions  
      • protraction & retraction
        • movement away from or toward the vertebral column
      • upward & downward rotation
        • upward rotation with arm elevation
        • downwared rotation with arm returning to side from raised position
      • internal & external rotation
      • anterior & posterior tipping
    • shoulder abduction
      • the ratio of glenohumeral motion to scapulothoracic motion is 2:1
        • GH does 120°, then ST does 60°
  • Stability
    • 17 different muscles attach to or originate from the scapula
      • trapezius 
      • serratus anterior 
      • deltoid 
      • latisimus dorsi 
      • levator scapulae 
      • rhomboid major 
      • rhomboid minor 
      • omohyoid - inferior belly 
      • pectoralis minor 
      • teres major 
      • teres minor 
      • triceps brachii 
      • biceps brachii 
      • coracobrachialis 
      • infraspinatus 
      • subscapularis 
      • supraspinatus 
Clinical
  • Scapulothoracic dissociation 
  • Scapular winging 
  • Scapulothoracic dyskinesis 

 

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