THE STERNOCLAVICULAR JOINT
(SEE FIGURE 3.39)
It is formed by the sternal end of the clavicle and the upper lateral part of the manubrium and the superior surface of the medial aspect of the cartilage of the first rib. It is a gliding joint, which has a fairly wide range of movement because of the presence of an articular disk within the capsule. The articular disk helps prevent medial dislocation of the clavicle. It is more common for the clavicle to break or the acromioclavicular joint to dislocate even before a medial dislocation at this joint could occur.
Four ligaments—the anterior sternoclavicular, pos-terior sternoclavicular, interclavicular, and costo-clavicular—support the joint. The attachment of theligaments is self-explanatory.
A wide range of gliding movements is possible. The movements are initiated in conjunction with the shoul-der movement. The muscles that move the shoulder also move this joint.