Manubriosternal Ligament

synchondrosis manubriosternalis

The manubriosternal joint (angle of Louis) is a fibrocartilaginous secondary cartilaginous joint between the manubrium and body of the sternum, palpable as the slight angle on the anterior chest at the level of the second rib.

Region: Chest

Biomechanics

Function & Actions

Allows slight movement between the manubrium and sternal body during respiration, absorbs forces transmitted through the sternum, and is the landmark for the sternal angle — the reference for counting ribs, identifying the carina level, and locating the second costal cartilage.

Clinical Relevance

Clinical Notes

The manubriosternal joint is the prime anatomical landmark for the thoracic angle of Louis — the sternal angle marks the junction of the superior and inferior mediastina, the level of the carina, the aortic arch, and the second rib. In closed chest cardiac massage, excessive force can disrupt this joint. Manubriosternal dislocation from high-energy trauma produces sternal instability.

Pathology

Common Injuries & Conditions

Manubriosternal Joint Dislocation

High-energy anterior chest trauma displacing the manubrium posteriorly on the sternal body, associated with great vessel and cardiac injury requiring CT angiography.

Manubriosternal Joint as Angle of Louis

The manubriosternal joint palpated as the anterior sternal step used for rib counting, carina level estimation, and second intercostal space identification in clinical examination.