Acromioclavicular Joint

The shoulder complex consists of four distinct articulations the glenohumeral joint, the acromioclavicular joint, the sternoclavicular joint, and the scapulothoracic articulation. The wide range of motion of the shoulder (exceeding a hemisphere) is the result of synchronous, simultaneous contributions from each joint The most important function of the shoulder is arm elevation. Several investigators have attempted to relate glenohumeral and scapulothoracic motion during arm elevation in various planes... 

True separation of the acromioclavicular joint occurs rarely. Distinction from physeal separations requires MR imaging, but this is not normally indicated as treatment is the same as for lateral clavicular fractures. Stress films are not routinely indicated. Full functional recovery can be expected (Taft et al 1987 Tibone et al 1992). Acromioclavicular injury in association with avulsion of the coracoid has been described (Combalia et al. 1995). 

Black GB, McPherson JA, Reed MH (1991) Traumatic pseudodislocation of the acromioclavicular joint in children. Am J Sports Med 19 644-646... 

Taft TN, Wilson FC, Oglesby JW (1987) Dislocation of the acromioclavicular joint an end result study. J Bone Joint Surg (Am) 69 1045-1051... 

The acromioclavicular joint is a planar joint. Occasionally there is an intra-articular plate between the surfaces that acts much as a disc. The acromioclavicular joint permits motion of the lateral end of the clavicle in an anteroposterior or cephalad-caudal direction, as well as rotation. More motion is possible at the lateral end of the clavicle because of the crank-like shape of the bone. 

The primary motion of the acromioclavicular joint is axial rotation. 

In the second phase (90 to 150 degrees), upward rotation of the scapula causes the glenoid fossa to tilt and face upwards as the humerus locks on the glenoid fossa. The trapezius and serratus anterior primarily contribute. The movement is restricted to some extent by the pectoralis major and latissimus dorsi but is facilitated by concomitant rotations of the sternoclavicular and acromioclavicular joints. 

The clavicle moves during most shoulder activity. Dysfunctions in clavicular motion can interfere with normal shoulder movement. The combined axial rotation of the sternoclavicular joint (30 degrees) and the acromioclavicular joint (30 degrees) allows the normal 60 degrees of rotation of the scapula on full abduction of the shoulder. 

Most articular somatic dysfunctions ofthe shoulder girdle occur at the sternoclavicular or acromioclavicular joints. These dysfunctions are characterized by pain at the involved joint and restricted motion in one or more of the planes of joint motion. 

Acetabular component, in hip replacement, 45-14 Acetabular fossae, 49-12 Acetol homopolymer, 44-8 Achromatopsia, 4-8 Acromioclavicular joint... 

Clinical Anatomy 190 Osseous and Articular Anatomy 190 Glenohumeral Joint 190 Acromioclavicular Joint 191 Sternoclavicular Joint 193 Scapulothoracic Plane 193 Muscles and Tendons 193 Rotator Cuff 193... 

The acromioclavicular joint is a small synovial joint located between the medial end of the acromion and the lateral end of the clavicle. It has a limited range... 

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