Glenohumeral joint

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Glenohumeral joint
Gray327.png
The right shoulder and Glenohumeral joint
Latinarticulatio humeri
Gray'ssubject #82 315
MeSHGlenohumeral+Joint
 
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Glenohumeral joint
Gray327.png
The right shoulder and Glenohumeral joint
Latinarticulatio humeri
Gray'ssubject #82 315
MeSHGlenohumeral+Joint

The glenohumeral joint, (from ancient Greek glene, eyeball, puppet, doll + -oid, 'form of', + Latin humerus, shoulder) or shoulder joint, is a multiaxial synovial ball and socket joint and involves articulation between the glenoid fossa of the scapula (shoulder blade) and the head of the humerus (upper arm bone). Due to the very limited interface of the humerus and scapula, it is the most mobile joint of the human body.

Contents

Movements

The glenoid fossa is shallow and contains the glenoid labrum which deepens it and aids in stability. With 120 degrees of unassisted flexion, the glenohumeral joint is the most mobile joint in the body.

Scapulohumeral rhythm helps to achieve further range of movement. The Scapulohumeral rhythm is the movement of the scapula across the thoracic cage in relation to the humerus. This movement can be compromised by anything that changes the position of the scapula. This could be an imbalance in the muscles that hold the scapula in place which are the upper and lower trapezium. This imbalance could cause a forward head carriage which in turn can affect the range of movements of the shoulder.

The rotator cuff muscles of the shoulder produce a high tensile force, and help to pull the head of the humerus into the glenoid fossa.

Movements of the shoulder joint[1]
MovementMusclesOriginInsertion
Flexion
(150°–170°)
Anterior fibers of deltoidClavicleMiddle of lateral surface of shaft of humerus
Clavicular part of pectoralis majorClavicleLateral lip of bicipital groove of humerus
Long head of biceps brachiiSupraglenoid tubercle of scapulaTuberosity of radius, Deep fascia of forearm
Short head of biceps brachiiCoracoid process of scapula
CoracobrachialisCoracoid processMedial aspect of shaft of humerus
Extension
(40°)
Posterior fibers of deltoidSpine of scapulaMiddle of lateral surface of shaft of humerus
Latissimus dorsiIliac crest, lumbar fascia, spines of lower six thoracic vertebrae, lower 3–4 ribs, inferior angle of scapulaFloor of bicipital groove of humerus
Teres majorLateral border of scapulaMedial lip of bicipital groove of humerus
Abduction
(160°–180°)
Middle fibers of deltoidAcromion process of scapulaMiddle of lateral surface of shaft of humerus
SupraspinatusSupraspinous fossa of scapulaGreater tuberosity of humerus
Adduction
(30°–40°)
Sternal part of pectoralis majorSternum, upper six costal cartilagesLateral lip of bicipital groove of humerus
Latissimus dorsiIliac crest, lumbar fascia, spines of lower six thoracic vertebrae, lower 3-4 ribs, inferior angle of scapulaFloor of bicipital groove of humerus
Teres majorLower third of lateral border of scapulaMedial lip of bicipital groove of humerus
Teres minorUpper two thirds of lateral border of scapulaGreater tuberosity of humerus
Lateral rotation
(in abduction: 95°;
in adduction: 70°)
InfraspinatusInfraspinous fossa of scapulaGreater tuberosity of humerus
Teres minorUpper two thirds of lateral border of scapulaGreater tuberosity of humerus
Posterior fibers of deltoidSpine of scapulaMiddle of lateral surface of shaft of humerus
Medial rotation
(in abduction: 40°–50°;
in adduction: 70°)
SubscapularisSubscapular fossaLesser tuberosity of humerus
Latissimus dorsiIliac crest, lumbar fascia, spines of lower 3-4 ribs, inferior angle of scapulaFloor of bicipital groove of humerus
Teres majorLower third of lateral border of scapulaMedial lip of bicipital groove of humerus
Anterior fibers of deltoidClavicleMiddle of lateral surface of shaft of humerus

Capsule

The glenohumeral joint has a loose capsule that is lax inferiorly and therefore is at risk of dislocation inferiorly. The long head of the biceps brachii muscle travels inside the capsule to attach to the supraglenoid tubercle of the scapula.

Because the tendon is inside the capsule, it requires a synovial tendon sheath to minimize friction.

A number of bursae in the capsule aid mobility. Namely, they are the subdeltoid bursa (between the joint capsule and deltoid muscle), subcoracoid bursa (between joint capsule and coracoid process of scapula), coracobrachial bursa (between subscapularis muscle and tendon of coracobrachialis muscle), subacromial bursa (between joint capsule and acromion of scapula) and the subscapular bursa (between joint capsule and tendon of subscapularis muscle, also known as subtendinous bursa of subscapularis muscle). The bursa are formed by the synovial membrane of the joint capsule. An inferior pouching of the joint capsule between teres minor and subscapularis is known as the axillary recess.

The shoulder joint is a muscle dependent joint as it lacks strong ligaments.[citation needed]

Ligaments

Nerve Supply

Blood Supply

The glenohumeral joint is supplied with blood by branches of the anterior and posterior circumflex humeral and suprascapular arteries.

Pathology

The capsule can become inflamed and stiff, with abnormal bands of tissue (adhesions) growing between the joint surfaces, causing pain and restricting movement of the shoulder, a condition known as frozen shoulder or adhesive capsulitis.

Additional images

See also

Notes

  1. ^ Snell, Appendix, pp 427-428

References

External links