anatomy of AC joint

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Anatomy of Acromioclavicular (AC) Joint The AC joint is one of the four major articulations associated with the shoulder complex. The joint is located on the outer part of the clavicle and is joined to a projection on the top of the scapula. The AC joint helps form the highest part of the shoulder. This joint allows a small amount of movement to occur between the clavicle and the acromion process. The AC joint allows the ability to raise the arm above the head. This joint functions as a pivot point (although technically it is a gliding synovial joint), acting like a strut to help with movement of the scapula resulting in a greater degree of arm rotation. The AC joint is stabilized by 3 ligaments; the acromioclavicular ligament, the coracoacromial ligament, and the coracoclavicular ligament. The acromioclavicular ligament attaches the clavicle to the acromion of the scapula. There are two parts to this ligament; superior and inferior. Superior acromioclavicular ligament this ligament is a quadrilateral band, covering the superior part of the articulation, and extending between the upper part of the lateral end of the clavicle and the adjoining part of the upper surface of the acromion. Inferior Acromioclavicular Ligament This ligament is somewhat thinner than the preceding, it covers the under part of the articulation, and is attached to the adjoining surfaces of the two bones. The coracoacromial ligament runs from the coracoid process and the acromion. The coracoacromial ligament is a strong triangular band, extending between the coracoid process and the acromion. It is attached, by its apex, to the summit of the acromion just in front of the articular surface for the clavicle; and by its broad base to the whole length of the lateral border of the coracoid process. This ligament, together with the coracoid process and the acromion, forms a vault for the

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