SHOULDER JOINT

Shoulder joint
- Type
  - Ball and socket , synovial
- Articular surface
  - Glenoid cavity of scapula
  - Head of humerus
- Features
  - Weak joint
    - Due to small and shallow to hold head of humerus in place
  - But permits great mobility
  - Stability factors
    - 1. Coraclacromial arch or secondayr socket for head of humrus
    - 2. Musculotendinous cuff
    - 3. Glenoidal labrum helps in deeping glenoid fossa
    - 4. Muscles attaching humerus to pectoral girdle
    - 5. Atmospheric presure
- Ligaments
  - Capsular ligament
    - Very loose ,
    - permits free movements ,
    - least supported
      - Inferiorly , where dislocation common
        
        May damage axillary nerve
      - Medially
        
        Attached to scapula beyond supraglenoid tubercle and margins of labrum
      - Laterally
        
        Attached to anatomical neck of humerus
      - Exception
        
        Inferiorly attachment extends to surgical neck
        
        Superiorly - deificient for passage of long head of tendon of biceps brachi
        
        Anteriorly - capsule is reinforced by supplemental bands called
        
        Glenohumeral ligaments.
        
        Superior , middle and inferior
        
        Area between superior and inferior glenohumeral ligament is a point of weakness in capsule ( foramen of weitbrecht )
        
        Anterior dislocation of humeral head
        
        Capsule lined by synovial membrane
        
        An extension of this forms a tubular sheath for tendon of long head of biceps brachii
  - Coracohumeral ligament
    - Extent.
      - From root of coracoid process to neck of humerus opposite greater tubercle
        
        Gives strength to capsule
  - Transverse humeral ligament
    - Bridges upper part of bicipital groove of humerus
    - Between greater and lesser tubercle
    - Tendons passes deep to it
  - Glenoidal labrum
    - Fibrocartilaginous rim
    - covers margins of glenoid cavity
- Bursae
  - Subacromial or deltoid bursa (A)
  - Subscaoularis bursa (B)
  - Infraspinatus bursa
  - A and B are commonly continuous with each other but may be separate
- Relations
  - Superiorly - coraclacromial bursa , subacromial bursa , supraspinatus , deltoid
  - Inferiorly - long head of triceps , axillary nerves , posterior circumflex humeral artery
  - Anteriroyl - subscaoularis , coracobrahialis, deltoid, short head of biceps
  - Posteriorly - infraspinatus , teres minor , deltoid
  - Within joint - tendon of long head of biceps brachii
- Blood supply -
  - Anterior circumflex humeral vessels
  - Posterior circumflex humeral vessels
  - Suorascapular vessels
  - Subscapular vessels
- Nerve supply
  - Axillary nerve
  - Musculocutaneous nerve
  - Suorascapular nerve
- Movements
  - Flexion
  - Extension
  - Parallel to glenoid cavity
  - Adduction
  - Abduction
  - Medial rotation
  - Lateral rottation
  - Circumduction


Type	Synovial ball and socket joint; multiaxial
Articular surfaces	Glenoid fossa of scapula, head of humerus; glenoid labrum
Ligaments	Superior glenohumeral, middle glenohumeral, inferior glenohumeral, coracohumeral, transverse humeral
Innervation	Subscapular nerve (joint); suprascapular nerve, axillary nerve, lateral pectoral nerve (joint capsule)
Blood supply	Anterior and posterior circumflex humeral, circumflex scapular and suprascapular arteries
Movements	Flexion, extension, abduction, adduction, external/lateral rotation, internal/medial rotation and circumduction
Rotator cuff muscles	Supraspinatus, infraspinatus, teres minor, subscapularis
	Mnemonic: Rotator cuff SITS on the shoulder