The sternoclavicular joint or sternoclavicular articulation is a synovial

saddle The saddle is a supportive structure for a rider of an animal, fastened to an animal's back by a girth. The most common type is equestrian. However, specialized saddles have been created for oxen, camels and other animals. It is not k ...

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 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 r ...

, as well as the first rib. The joint possesses a

joint capsule In anatomy, a joint capsule or articular capsule is an envelope surrounding a synovial joint.articular disk The articular disk (or disc) is a thin, oval plate of fibrocartilage present in several joints which separates synovial cavities. This separation of the cavity space allows for separate movements to occur in each space. The presence of an articula ...

, and is reinforced by multiple ligaments.

Structure

The joint is structurally classed as a synovial plane joint and functionally classed as a diarthrosis and multiaxial joint. It is composed of two portions separated by an

articular disc The articular disk (or disc) is a thin, oval plate of fibrocartilage present in several joints which separates synovial cavities. This separation of the cavity space allows for separate movements to occur in each space. The presence of an articula ...

of fibrocartilage. The joint is formed by the sternal end of the clavicle, the clavicular notch (the superior and lateral part of the sternum), and (the superior surface of) the cartilage of the

first rib The rib cage, as an enclosure that comprises the ribs, vertebral column and sternum in the thorax of most vertebrates, protects vital organs such as the heart, lungs and great vessels. The sternum, together known as the thoracic cage, is a semi ...

(visible from the outside as the

suprasternal notch The suprasternal notch, also known as the fossa jugularis sternalis, jugular notch, or Plender gap, is a large, visible dip in between the neck in humans, between the clavicles, and above the manubrium of the sternum. Structure The suprasternal ...

). 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 The suprascapular artery is a branch of the thyrocervical trunk on the neck. Structure At first, it passes downward and laterally across the scalenus anterior and phrenic nerve, being covered by the sternocleidomastoid muscle; it then crosses ...

. It is innervated via the medial supraclavicular nerve (superficially), and the

nerve to subclavius The subclavian nerve, also known as the nerve to the subclavius, is small branch of the upper trunk of the brachial plexus. It contains axons from C5 and C6. The subclavian nerve innervates the subclavius muscle. Structure The subclavian ner ...

(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 Loose connective tissue, sometimes called areolar tissue, is a cellular connective tissue with thin and relatively sparse collagen fibers. Its ground substance occupies more volume than the fibers do. It has a viscous to gel-like consistenc ...

Articular disc

The joint features a

fibrocartilaginous 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 ...

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 The costoclavicular ligament, also known as the rhomboid ligament or Halsted's ligament, is a ligament of the shoulder girdle. It is short, flat, and rhomboid in form. It is the major stabilizing factor of the sternoclavicular joint and is the a ...

is the main limitation to movement, and therefore the main stabilizer of the joint. *

Anterior sternoclavicular ligament The anterior sternoclavicular ligament is a broad band of fibers attached to the clavicle above, and to the manubrium below. The ligament overlies the anterior (front) surface of sternoclavicular joint. Anatomy Attachments It is attached sup ...

(intrinsic) *

Posterior sternoclavicular ligament The posterior sternoclavicular ligament is a band of fibers, covering the posterior surface of the sternoclavicular joint. It is attached above to the upper and back part of the sternal end of the clavicle, and, passing obliquely downward and med ...

(intrinsic) *

Costoclavicular ligament The costoclavicular ligament, also known as the rhomboid ligament or Halsted's ligament, is a ligament of the shoulder girdle. It is short, flat, and rhomboid in form. It is the major stabilizing factor of the sternoclavicular joint and is the a ...

(extrinsic) *

Interclavicular ligament The interclavicular ligament is a flattened band, which varies considerably in form and size in different individuals, it passes in a curved direction from the upper part of the sternal end of one clavicle to that of the other, and is also attache ...

(extrinsic)

Function

The sternoclavicular joint allows movement of the

in three planes, predominantly in the

anteroposterior Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

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 Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relativ ...

and retraction 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 In materials science, a partial dislocation is a decomposed form of dislocation that occurs within a crystalline material. An ''extended dislocation'' is a dislocation that has dissociated into a pair of partial dislocations. The vector sum of t ...

mayalso sometimes occur.

Other

SAPHO syndrome SAPHO syndrome includes a variety of inflammatory bone disorders that may be associated with skin changes. These diseases share some clinical, radiologic, and pathologic characteristics. An entity initially known as chronic recurrent multifocal ...

there may be

arthropathy An arthropathy is a disease of a joint. Types Arthritis is a form of arthropathy that involves inflammation of one or more joints, while the term arthropathy may be used regardless of whether there is inflammation or not. Joint diseases can be ...

of the sternoclavicular joint.

Septic arthritis Acute septic arthritis, infectious arthritis, suppurative arthritis, osteomyelitis, or joint infection is the invasion of a joint by an infectious agent resulting in joint inflammation. Generally speaking, symptoms typically include redness, h ...

may rarely affect the sternoclavicular joint.

References

External links

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