Acromioclavicular joint
Updates to Article Attributes
The acromioclavicular (AC) joint is a plane synovial joint of the pectoral girdle.
Gross anatomy
The AC joint is between the small facets of the convex distal clavicle and flat medial acromion. The articular surfaces are lined with hyaline cartilage 4. A wedge-shaped articular disc made from fibrocartilage separates the two articular surfaces, but its function is unknown 2, 6.
A weak, synovium-lined joint capsule is attached to the articular margins and is reinforced superiorly by blended fibres of the trapezius muscle 6.
Ligaments
Static stabilisation is provided by:
- coracoclavicular ligament: main stabliser 2, 5
- superior and inferior acromioclavicular ligaments: reinforce the relatively weak joint capsule 5
Dynamic stabilisation is also provided by the deltoid and trapezius muscles, with the superior AC ligament blending with these muscles' aponeuroses.
Blood supply
- arterial supply: suprascapular and thoraco-acromial arteries 6
Nerve supplyInnervation
- axillary, suprascapular and lateral pectoral nerves 2, 6
Variant anatomy
Related pathology
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