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
- 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 |
Discussion