Location – upper limb joint
Bones involved – humeral head and glenoid fossa of the scapula
Type of joint – ball and socket synovial joint
Movements – flexion, extension, abduction, adduction, internal and external rotation, circumduction
Bony congruance – poor bony congruence- only 1/3 of the ball of humerus articulates with the relatively flat glenoid fossa – inherent instability of this joint
Muscle – rotator cuff muscles supraspinatus, infraspinatus, teres minor, and subscapularis all attach to the capsule and actively contribute to joint stability. Deltoid and Long head of triceps prevents inferior dislocation in shoulder abduction.
Ligament – glenohumeral ligaments – anteriorly, coracohumeral superiorly, extrinsic- corocoacromial arch superiorly.
Other – the fossa is deepened by the fibrocartilagenous glenoid labrum, fibrous joint capsule(anatomical neck to glenoid)
Blood supply – ant and post humeral circumflex arteries and suprascapular artery
Nerves – axillary, suprascapular and lateral pectoral nerves.
Muscular/tendinous attachments to the scapula:
Bony features attachments of rotator cuff muscles
supraspinatus, infraspinatus and teres minor on greater humeral tubercle.
subscapularis on lesser tubercle.
Contents of bicipital groove
Tendon of long head of biceps brachii, its synovial sheath
Proximal end of humerus
- Anatomical neck (above tubercles)
- Greater(lat) and lesser tubercles(ant)
- Intertubercular sulcus
- Deltoid tuberosity laterally
- Radial groove posteriorly (contains radial nerve and profunda brachii artery.
Brachial plexus organisation:
Roots between the scalenus anterior & scalenus medius
Trunks in the posterior triangle of the neck
Divisions behind the clavicle (at the outer border of the first rib)
Cords in the axilla (clasping the second part of the axillary artery)
Definitive nerves of supply forming in the lateral part of the axilla