Anatomy of the A/C joint

The acromio-clavicular, or A/C joint, is where the collarbone (the clavicle) is joined to a part of the shoulder blade (the scapula) called the acromion. A strong capsule and the acromio-clavicular ligaments surround this joint and keep the ends of the two bones correctly aligned. A second ligament between the end of the clavicle and a part of the scapula called the coracoid process is also an important part of this joint. This ligament is called the coraco-clavicular ligament.

The ends of the bones of the acromion and the clavicle are covered with a layer of surface cartilage. The surface cartilage helps the ends of the two bones slide smoothly on each other. This cartilage is important for maintaining the normal and full range of motion of the shoulder. The A/C joint can be a common source of pain and problems with the shoulder. Most of these problems are caused by wear and tear on the surface cartilage, sprains and tears in the ligaments, or fractures of the collarbone. Thus the three most common problems that occur with this joint are arthritis, fractures, and dislocations of the A/C joint.

back to top | back to the A/C Joint | next page