Shoulder Girdle Flashcards
What is the structure of the glenohumeral joint capsule?
fibrous, loose cylindrical sleeve
majority of fibres pass horizontally - between scapula and humerus
– some oblique and transverse fibres present
relatively lax - meaning the GH joint is unstable
what are the attachments of the GH joint capsule?
scapula
- anteriorly and inferiorly - to outside glenoid labrum
- superiorly and posteriorly - to the labrum
humerus
- anatomical neck
- articular margins of the head - medial to greater and lesser tubercles
- inferiorly to the medial surface of the shaft - 1cm below articular margin
describe the openings of the GH joint capsule?
three openings
- inferiorly = upper end of intertuberclar groove - for long head of biceps
- anteriorly = between middle and superior GH ligaments - for subscapular bursa
- posteriorly = for infraspinatus bursa
Where is the GH joint capsule strengthened?
Thick and strong anteriorly - by 3x GH ligaments
stabilised superoposteriorly at the humeral attachment by the coracohumeral ligament
Lax in all other areas
Describe the structure of the synovial membrane of the GH joint?
attaches to the articular margins
extends downwards as a pouch when the arm is relaxed
reflects upwards on medial side of humeral shaft
extends through anterior and posterior openings of the capsule - to form subscapular and infraspinous bursa
forms a double layer tubular sheets around long head of biceps
Describe the articular surface of the humerus in the GH joint?
lined in hyaline cartilige
2/5th of a sphere
faces superiorly, medially and posteriorly
Describe the articular surfaces of the glenoid in the GH joint
Superolateral angle of the scapula
faces laterally, anteriorly and slightly superiorly
Pear-shaped - narrower superiorly
concave transversely and vertically
irregular concavity (less deep than convexity of humerus) only 1/3rd humeral head in contact with glenoid fossa at any time
Classify the GH joint
complex, synovial, multiaxial, ball and socket joint
Name the nerve supply to the GH joint
twigs from the supra scapular, axillary, subscapular, lateral pectoral and musculocutaneous nerves
C5,6,7
What are the static stabilisers of the GH joint
Glenoid labrum - deepens the fossa
Coracoaromial arch - superior stability
anterolateral angled position of glenoid fossa - posterior stability
What are the dynamic stabilisers of the GH joint
Rotator cuff muscles - fuse with lateral JC - act as ligaments
Superior stability - long head of biceps
inferior stability - long head of triceps
posterior stability - teres minor
Describe the structure of the glenoid labrum
firbocartilagenous rim
triangular in cross section
thin free edge
4mm deep
Attachments of the glenoid labrum
Base - to margin of glenoid fossa
outer surface- to joint capsule - posteriosuperiorly
Inner surface/central portion - continuous with cartilage of glenoid fossa
Upper part - not fixed - projects into the joint
what does the outer margin of the glenoid labrum give attachment for?
long head of biceps tendon superiorly
long head of triceps tendon inferiorly
What is the subscapularis bursa?
extension of SM through anterior opening of JC
lies above subscapularis tendon, below the coracoid process
