sternokostalis

The sternokostalis, or sternocostal joints, are the articulations between the sternum and the costal cartilages of the ribs. They form a key part of the thoracic cage, linking the rib cage to the sternum and contributing to chest wall mobility during breathing.

The first sternocostal joint is a primary cartilaginous joint (synchondrosis) between the first costal cartilage and the manubrium, and it typically ossifies with age. The joints between the costal cartilages of ribs 2 through 7 and the sternum are synovial plane joints, allowing small gliding movements that assist rib expansion during respiration.

Each sternocostal joint is surrounded by a joint capsule and reinforced by ligaments, notably the radiate sternocostal ligaments that extend from the sternum to the costal cartilages. These joints may be supported by additional fibrous connections and are intimately related to surrounding intercostal muscles and their fascia.

The sternocostal joints are innervated primarily by the ventral rami of the intercostal nerves, providing sensory input that contributes to chest wall sensation. Blood supply to the region is from branches of the intercostal arteries, including the internal thoracic and musculophrenic arteries.

Functionally, the sternocostal joints permit limited movements that facilitate rib elevation and chest expansion during inspiration. With aging, calcification or degenerative changes can limit mobility. Clinically, inflammatory conditions such as costochondritis or traumatic injury to the costal cartilages or joints can produce chest pain localized to these areas.