The sternoclavicular joint or sternoclavicular articulation is a synovial

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joint A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw ...

between the manubrium of the sternum, and the clavicle, as well as the first rib. The joint possesses a joint capsule, and an articular disk, and is reinforced by multiple ligaments.

Structure

The joint is structurally classed as a synovial

plane joint A plane joint (arthrodial joint, gliding joint, plane articulation) is a synovial joint A synovial joint, also known as diarthrosis, joins bones or cartilage with a fibrous joint capsule that is continuous with the periosteum of the joined bones ...

and functionally classed as a diarthrosis and multiaxial joint. It is composed of two portions separated by an articular disc of

fibrocartilage Fibrocartilage consists of a mixture of white fibrous tissue and cartilaginous tissue in various proportions. It owes its inflexibility and toughness to the former of these constituents, and its elasticity to the latter. It is the only type of ...

. The joint is formed by the sternal end of the clavicle, the

clavicular notch The clavicle, or collarbone, is a slender, S-shaped long bone approximately 6 inches (15 cm) long that serves as a strut between the shoulder blade and the sternum (breastbone). There are two clavicles, one on the left and one on the rig ...

(the superior and lateral part of the sternum), and (the superior surface of) the cartilage of the first rib (visible from the outside as the suprasternal notch). The articular surface of the clavicle is larger than that of the sternum, and is invested with a layer of cartilage, which is considerably thicker than that of the sternum. The joint receives arterial supply via branches of the internal thoracic artery, and of the suprascapular artery. It is innervated via the medial supraclavicular nerve (superficially), and the nerve to subclavius (deeply).

Joint capsule

The joint capsule is thickened anteriorly and posteriorly, but is meagre superiorly and (especially) posteriorly, where it consists mostly of loose areolar connective tissue.

Articular disc

The joint features a fibrocartilaginous articular disc which completely divides the joint to form two articular compartments. the disc acts to increase the range of movement of the joint.

Ligaments

The joint is reinforced by two intrinsic and two extrinsic ligaments. The costoclavicular ligament is the main limitation to movement, and therefore the main stabilizer of the joint. * Anterior sternoclavicular ligament (intrinsic) * Posterior sternoclavicular ligament (intrinsic) * Costoclavicular ligament (extrinsic) * Interclavicular ligament (extrinsic)

Function

The sternoclavicular joint allows movement of the clavicle in three

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, predominantly in the anteroposterior and vertical planes, although some rotation also occurs. A description of movement would be elevation and depression. Muscles do not directly act on this joint, although almost all actions of the shoulder girdle or the scapula will cause some motion at this articulation. The unique double-hinged articular disk found at the junction of the clavicular head and manubrium allows for movement between the clavicle and the disk during elevation and depression of the scapula. This disk also allows motion between the sternum (manubrium) and itself during protraction and

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of the scapula.

Clinical significance

Dislocation

Sternoclavicular dislocation is rare, but may result from direct trauma to the clavicle or indirect forces applied to the shoulder. Posterior dislocations deserve special attention, as they have the potential to be life-threatening because of the risk of damage to vital structures in the mediastinum; surgery can be used to fix such dislocations, as they are unlikely to heal by themselves. A spontaneous partial dislocation mayalso sometimes occur.

Other

In SAPHO syndrome there may be arthropathy of the sternoclavicular joint. Septic arthritis may rarely affect the sternoclavicular joint.

References

External links

Overview at ouhsc.edu
* {{Authority control Joints Thorax (human anatomy)