The acromioclavicular joint is surrounded by a joint capsule and is reinforced by: a small acromioclavicular ligament superior to the joint and passing between adjacent regions of the clavicle and acromion, and a much larger coracoclavicular ligament, which is not directly related to the joint, but is an important strong accessory ligament, providing much of the weight-bearing support for the upper limb on the clavicle and maintaining the position of the clavicle on the acromion—it spans the distance between the coracoid process of the scapula and the inferior surface of the acromial end of the clavicle and comprises an anterior trapezoid ligament (which attaches to the trapezoid line on the clavicle) and a posterior conoid ligament (which attaches to the related conoid tubercle).