Orthopedics Book

Infectious Disease

Thoracic Spine Disorders

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Shoulder Anatomy

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  1. See Also
    1. Shoulder History
    2. Shoulder Exam
    3. Shoulder Pain
  2. Anatomy: Bones
    1. Scapula
      1. Scapular spine
        1. Third thoracic vertebrae
      2. Scapular inferior angle
        1. Eighth thoracic vertebrae (7th rib)
    2. Clavicle
    3. Humerus
  3. Anatomy: Muscles attaching Axial skeleton to Scapula
    1. Trapezius
    2. Levator scapulae
    3. Rhomboids
    4. Serratus anterior
  4. Anatomy: Muscles attaching Axial skeleton to Humerus
    1. Latissimus dorsi
    2. Pectoralis major
  5. Anatomy: Articulations
    1. Glenohumeral joint (GH Joint)
      1. Glenoid of scapula meets humeral head
      2. Golf ball on golf tee
        1. Articulation with bone: 30%
        2. Articulation with glenoid labrum: 75%
    2. Posterior Chest Wall (Scapulothoracic articulation)
    3. Acromioclavicular Joint (AC Joint)
      1. Acromion of scapula meets the clavicle
    4. Sternoclavicular Joint (SC Joint)
  6. Anatomy: Subacromial Space
    1. Rotator cuff composition (mnemonic: SITS Muscles)
      1. Anterior Rotator Cuff
        1. Subscapularis Muscle
      2. Posterior Rotator Cuff
        1. Infraspinatus Muscle
        2. Teres Minor Muscle
      3. Superior Rotator Cuff
        1. Supraspinatus Muscle
    2. Subacromial bursae
      1. Separates cuff from overlying coracoacromial arch
      2. Includes subdeltoid bursa and subcoracoid bursa
  7. Physiology: Function
    1. Scapula stabilized prior to arm movement
    2. Rotator Cuff (Musculotendinous)
      1. Steadies humeral head in glenoid
      2. Results in humeral head descent
    3. Scapulothoracic Musculature
      1. Results in forward and lateral scapula movement
      2. Initiates first 60-70 degrees of Shoulder Abduction
    4. Glenohumeral Musculature
      1. Deltoid and supraspinatus muscles
      2. Accounts for last two thirds of Shoulder Abduction
  8. Physiology: Muscle action at Glenohumeral joint
    1. Shoulder Abduction
      1. Middle deltoid muscle
      2. Supraspinatus muscle
    2. Shoulder Adduction
      1. Pectoralis major muscle
      2. Latissimus dorsi muscle
    3. Shoulder Flexion
      1. Anterior deltoid muscle
      2. Coracobrachialis muscle
    4. Shoulder Extension
      1. Posterior deltoid muscle
      2. Latissimus dorsi muscle
      3. Teres major muscle
    5. Shoulder Internal Rotation
      1. Pectoralis major muscle
      2. Latissimus dorsi muscle
      3. Teres major muscle
      4. Subscapularis muscle
    6. Shoulder External Rotation
      1. Infraspinatus muscle
      2. Teres Minor muscle

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