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The shoulder joint is the most mobile joint in the human body, allowing a wide range of motion but sacrificing some stability. It is a complex joint composed of multiple articulations and stabilized by muscles, ligaments, and the joint capsule.

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https://www.youtube.com/watch?v=NnBnmpkesA0

https://youtu.be/QOE9vlQQooI?si=WbGYIwxPinjwt7IL

https://www.youtube.com/watch?v=SfQzA6W5xA0

Anatomy

a. Articulations

The shoulder complex comprises three true joints and one pseudo-joint:

• Glenohumeral joint (GHJ): Between humeral head and glenoid fossa of scapula (ball-and-socket)
• Acromioclavicular joint (ACJ): Between acromion and lateral clavicle
• Sternoclavicular joint (SCJ): Between sternum and medial clavicle
• Scapulothoracic articulation: Functional articulation between scapula and thoracic cage
• Glenohumeral joint: Representative images

b. Stabilizing Structures

• Static stabilizers:
  • Glenoid labrum
  • Joint capsule
  • Glenohumeral ligaments (superior, middle, inferior)
  • Coracohumeral ligament
• Dynamic stabilizers:
  • Rotator cuff muscles:
    • Supraspinatus
    • Infraspinatus
    • Teres minor
    • Subscapularis
  • Long head of biceps tendon

https://youtu.be/zdhGIjcCVB8?si=ZET1k_0yEqfOP1Gu

https://youtu.be/Fi-q4SpIYU4?si=yjSdB4vi4-xzqEgt

c. Bursae

• Subacromial-subdeltoid bursa (largest)