The Acromioclavicular Joint Flashcards
What kind of joint is the acromioclavicular?
A plane type of synovial joint
Where is the acromioclavicular joint located?
Where the lateral end of the clavicle articulates with the acromion of the scapula
Where can the acromioclavicular joint be palpated?
During a shoulder examination, 2-3cm medially from the ‘tip’ of the shoulder
What is the shoulder formed by?
The end of the acromion
What does the acromioclavicular joint consist of?
An articulation between the lateral end of the clavicle and the acromion of the scapula
What are the atypical features of the acromioclavicular joint?
The articular surfaces of the joint are lined with fibrocartilage (as opposed to hyaline cartilage)
The joint cavity is partially divided by an articular disc
What is the articular disc of the acromioclavicular joint?
A wedge of fibrocartilage suspended from the upper part of the capsule
What does the joint capsule of the acromioclavicular joint consist of?
A loose fibrous layer which encloses the two articular surfaces
What does the joint capsule give rise to?
The articular disc
What is the posterior aspect of the joint capsule reinforced by?
Fibres from the trapezius muscle
What is the joint capsule of the acromioclavicular joint lined internally by?
A synovial membrane
What does the synovial membrane of the joint capsule do?
Secretes synovial fluid into the cavity of the joint
What are the major ligaments present in the acromioclavicular joint?
Acromioclavicular
Conoid
Trapezoid
Where does the acromioclavicular ligament run?
Horizontally from the acromion to the lateral clavicle
What does the acromioclavicular ligament do?
Covers the joint capsule, reinforcing its superior aspect
Where does the conoid ligament run?
Vertically form the coracoid process of the scapula to the conoid tubercle of the clavicle
Where does the trapezoid ligament run?
From the coracoid process of the scapula to the trapezoid line of the clavicle
What are the conoid and trapezoid ligaments collectively known as?
The coracoclavicular ligament
What does the coracoclavicular ligament do?
Effectively suspends the weight of the upper limb from the clavicle
What does the acromioclavicular joint allow?
A degree of axial rotation and anterioposterior movement
Which muscles act on the acromioclavicular joint?
None
What is the result of no muscles acting on the acromioclavicular joint?
All movement is passive, and initiated by movement at other joints
What is the arterial supply to the acromioclavicular joint via?
The suprascapular artery
The thoraco-acromial artery
What does the suprascapular artery arise from?
The subclavian artery at the thyrocervical trunk
What does the thoraco-acromial artery arise from?
The axillary artery
What are the veins of the acromioclavicular joint?
They follow the major arteries
What is the acromioclavicular joint innervated by?
Articular branches of the suprascapular and lateral pectoral nerves
Where do the nerves innervating the acromioclavicular joint arise from?
The brachial plexus
When does acromioclavicular joint dislocation occur?
When the two articulating surfaces of the joint are separated
What is acromioclavicular joint dislocation associated with?
Joint soft tissue damage
What does acromioclavicular joint dislocation commonly occur from?
A direct blow to the joint, or a fall on an outstretched hand
When is a dislocation of the acromioclavicular joint more serious?
If a ligamental rupture occurs, of the acromioclavicular or the coracoclavicular ligaments
What happens is the coracoclavicular ligament is torn?
The weight of the upper limb is not supported, and the shoulder moves inferiorly, increasing the prominence of the clavicle
What does management of an AC joint dislocation depend on?
The injury severity and impact on quality of life
What do the treatment options of an AC joint dislocation range from?
Ice and rest, to ligament reconstruction surgery
