2)Osteology & Arthrology Glenohumeral Joint Flashcards
What does the triad-arrangement of the sternoclavicular, acromioclalivular and glenohumeral joint ensure
> Ensures that clavicular movements at the sternoclavicular and acromioclavicular joints are always associated with movements of the scapula
> And movements of the scapula are often accompanied by movements of the humerus at the glenohumeral joint.
What gives the upper limb its freedom of movement
Summation of the movements of these three individual yet mutually interdependent joints which gives the upper limb its freedom of movement.
Describe the articular surface
See file
Describe the fibrous capsule
See file
Synovial membrane
Bursa also included but on a separate card
Lines capsule extends downwards as a pouch when arm is hanging by the side
Attaches articular margin of both bones = reflected upwards on medial side of humeral shaft
Medial part of epiphyseal line Intercaspular but is extrasynovial
Limited posteriorly surface due to subscapularus tendon= may be sufficiently large to extend and lie below subcoracoid bursa
Double layer tubular sheath of synovial membrane continues with glenoid attachment encloses the intercaspular part of the long head of biceps
Caspular ligaments
Superior glenohumeral ligament
Middle glenohumeral ligament
Inferior glenohumeral ligament
Transverse humeral
Superior glenohumeral ligament
Slender
Lat, parallel bicep tendon to upper lesser tubercle
Glenoid margin + adjacent labrum ➖anterior attachment bicep
Middle glenohumeral ligament
Below superior glenohumeral ligament ➖ lesser tubercle below insertion of subscapularis
Inferior glenohumeral ligament
- most well developed occasionally absent
Obliquely
Glenoid margin below notch anterior boarder glenoid labrum➖ anteroinferior part neck of humerus
As it passes from scapula to humerus the upper part of the inferior ligament merges with lower part of middle glenohumeral ligament
Glenohumeral ligaments have no real stabilising function what movement increases and decreases tension in all 3 ligaments
Lateral rotation of humerus put all 3 ligaments under tension
Medial rotation relaxes all 3
Abduction – only the middle and inferior ligaments are taught superior is relaxed
Transverse humeral ligament
Upper end of inter-trabecular groove bridges gap between greater and lesser tubercles
Formed by some transverse capsular fibres
Holds biceps tendon in the intertrabecular grooves as it leaves joint
Bursas
- Subscapularis bursa- Synoival membrane Extends through interior opening of capsule
- Subcoracoid bursa- extension of subscapularis
- Infraspinatus bursa- posterior extension of the membrane through the joint capsule
- Subacromial bursa- important but non-communicating bursa associated with shoulder joint lies between and separates the coracoacromial arch and deltoid = form superolateral part of shoulder joint. Subdeltoid bursa- extends laterally under deltoid
Clinical significance of bursa
Adhesions made for preventing free gliding movement of shoulder
True for the biciptal sheath and subdeltoid bursa
Subdeltoid bursa= inflamed= bursitis then affects tendon of supraspinatis= rupture
Intra-articular structures
Glenoid labrum
Long head of biceps
Glenoid labrum
Triangular fibrocartilageinous rim
Thin free edge 4mm deep
Deepens glenoid fossa
Glenoid labrum attachments
Base of labrum attaches to margin of glenoid fossa
Outer surface gives attachment to joint capsule posteriorly and superiorly -gives attachment to long head of biceps superiorly
Inner joint surface is in contact with head of humerus and is lined by Cartilage continuous with that of glenoid fossa
Upper part of labrum not completely fixed to bone its inner edge may project into joint like a meniscus
Function of glenoid labrum
Deepens shoulder socket
- Reduces chance of dislocation by anchoring humeral head to scapula increasing contact 2mm AP and 4.5mm SI
- Provides insertion for stabilizing structures (Capsule and Glenohumeral Ligaments), as a fibrous “crossroad”
- Contributes to the “Viscoelastic Piston” effect
Long head of biceps
Runs intercaspularly from Supraglenoid tubercle and adjacent superior margin of glenoid leave room until emerges from the joint deep to the transverse humeral ligament
Intercourse purely and 2 cm beyond tendon is ensheathed into synovial sheath
Accessory ligaments
Coracohumeral ligament
Coracoacromial ligament
Coracohumeral ligament
Fairly strong broad
Laterally
Lateral boarder of coracoid process ➖becomes flattened with margins diverging above the intertubercular groove attaches to upper part of the anatomical neck - region of greater and lesser tubercles and intervening transverse ligament
Anterior boarder of medial ligament is free as it passes laterally fuses with tendon of subscapularus
Posterior part blends with the tendon of supraspinatus as it attaches to the superior facet on the greater tubercle of humerus
Coracoacromial - fibro-osseous arch above joint
Not directly associated with joint forms together with coracoid process and acromion of fibro-osseous arch above head of humerus
Strong triangular ligament
Posterior borders thicker than intermediate part
Attached by broadbase to the lateral border of horizontal part of coracoid process blunt apex attaching to the apex of acromion in front of acromioclavicular joint
In fairly separated from tendon of supraspinatus and shoulder joint by subacromial bursa
Arch of coracoacromial ligament
Arch formed by ligament and Boney processes increases the surface which the head of humerus is supported when forces are transmitted upwards along humerus
Roof of subacromial space - subacromial bursa sit in here= shoulder problems, long head of biceps and supraspinatus
Movements of Glenohumeral joint
Flexion Extension Abduction Adduction Medial rotation Lateral rotation
NOM and limiting factors flexion
0-180°
Extent of articular surfaces
Tension in capsular structures
Tension extensors
NOM and limiting factors Extension
0-50°
Extent of articular surfaces.
Tension in capsular structures +surrounding
Tension in flexors
NOM and limiting factors Abduction
0-150°
Glenohumeral ligs (middle and inferior bands) Inferior part of the fibrous capsule
NOM and limiting factors Adduction
0-40°
Extent of articular surface
NOM and limiting factors Medial rotation
0-80°
Posterior part of fibrous capsule
Posterior Laurel rotators (infraspinatus and teres minor)
NOM and limiting factors lateral rotation
0-90°
Anterior part of fibrous capsule
All three bands of the glenohumeral ligament.
Anterior video repeaters (subscapularis)
Nerve supply Glenohumeral joint
Super scapular Axillary Subscapular Lateral pectorial Musculocutaneous
C5,6,7
Stability
Incongruity and laxness= x stable
Glenoid labrum= deepens socket improves congruity = stabilises
Rotator cuff= fuses lateral part joint capsule holds humeral head in glenoid fossa
Coracoacromial arch= x displacement humerus
Combination movements of shoulder complex
Glenohumeral joint movement is responsible for bringing the arm to the horizontal position whilst the scapular movements of the pectoral girdle facilitate bringing the arm into a vertical position, eg. reaching above the head.
Glenohumeral joint range of movement
Shoulder complex
Relatively large due to incongruity of articular surfaces
Increased by movements of the pectoral girdle occurring simultaneously with that of the humeral head against the glenoid fossa.
Describe Shoulder flexion
Initial phase nearly all glenohumeral joint movement
However pectoral girdle movement occurs in order to laterally rotate and protract scapula to allow for 180 ̊ of flexion into elevation.
Describe Shoulder extension
Contribution of scapular movements during shoulder extension increases the range to
70 ̊- 90 ̊
Describe Shoulder abduction
Initial 25 ̊–30 ̊ of abduction is nearly all glenohumeral movement with no pectoral girdle involvement. Initiated by supraspinatus
After this point, movements of the shoulder complex occur with clavicular and scapular movements occurring simultaneously at the Sternoclavicular and Acromiocalavicular joints (Pectoral Girdle) with the Glenohumeral joint
Deltoid continues movement after initial 20° of abduction
Initially there is elevation of the Pectoral Girdle but by approximately 90˚ of abduction, the articular surfaces of these joints are exhausted and posterior axial rotation of the clavicle occurs allows further lateral rotation of the scapula.
Between 30 ̊ and 180 ̊, for every 15 ̊ of abduction, the shoulder is thought to contribute 10 ̊ whilst the scapula contributes 5 ̊.
This normal ratio of 2:1 of humeral-scapular movement permits full range of movement of the shoulder.
Referred to as the normal humeral-scapular rhythm
Final range of movement, lateral rotation of the humerus occurs this provides further articular surface on the humeral head for the glenoid fossa. Lateral rotation of the scapula causes the glenoid fossa to face superiorly which facilitates an increased ROM at the Glenohumeral joint.
Anything that prevents lateral rotation of the scapula will impair the range of movement of shoulder
Hypothesised to be necessary in order to prevent the greater tubercle impinging upon the coraco-acromial arch.
Shoulder adduction
Involves eccentric muscle activity of:
serratus anterior
trapezius
deltoid
supraspinatus
> in order to control medial rotation of the scapula as the arm returns to the side of
Classification glenohumeral joint
Ball and socket, simple, synovial, multiaxail
What is the Glenohumeral rhythm
Between 30˚ and 180˚, for every 15˚ of abduction, the shoulder is thought to contribute 10˚ whilst the scapula contributes 5˚. This normal ratio of 2:1 of humeral-scapular movement is essential to permit full range of movement of the shoulder
