How many ligaments stabilize the acromioclavicular joint?

• A. 2
• B. 3
• C. 4
• D. 5

Answer: (C)

Stability at the acromioclavicular joint comes from both capsule-supported ligaments and the strong suspensory ligaments between the clavicle and coracoid. There are two acromioclavicular ligaments—superior and inferior—that reinforce the joint capsule and resist horizontal movement between the clavicle and the acromion. There are two coracoclavicular ligaments—the conoid and the trapezoid—that anchor the clavicle to the coracoid process, providing vertical stability and limiting clavicular elevation. The coracoacromial ligament runs from the coracoid to the acromion but does not stabilize the AC joint itself. Taken together, four ligaments stabilize the AC joint.