Sternocostal Joints
Sternocostal joints attach the true ribs’ costal cartilages to the sternum, facilitating chest expansion.
Sternocostal joints are the articulations between the costal cartilages of the true ribs (ribs 1–7) and the lateral borders of the sternum. These joints play a key role in stabilizing the anterior thoracic cage while allowing limited movement during respiration. The first sternocostal joint is a synchondrosis, whereas the remaining are synovial joints.
Location
These joints are located on the anterior thoracic wall, where the costal cartilages of ribs 1 to 7 meet the sternum. Each joint corresponds to the costal notch of the manubrium, body, or manubriosternal junction, depending on rib level.
Joint Types
- 1st sternocostal joint: Primary cartilaginous joint (synchondrosis); allows no movement
- 2nd–7th sternocostal joints: Synovial plane joints (diarthroses); permit slight gliding movements during respiration
Articulating Structures
- Medial end of the costal cartilage (ribs 1–7)
- Costal notches of the sternum (manubrium or body, depending on the rib)
Ligaments
The sternocostal joints are reinforced by surrounding ligaments:
- Radiate sternocostal ligaments: Fan-shaped fibers extending from the costal cartilage to the anterior and posterior surfaces of the sternum
- Intra-articular ligament (2nd rib): Connects the second costal cartilage to the fibrocartilaginous manubriosternal junction
- Capsular ligaments: Surround the synovial cavities, providing structural integrity
Movements
- 1st joint: Immobile (synchondrosis)
- 2nd–7th joints: Allow slight gliding movements during inspiration and expiration
Function
- Anchor the anterior ends of the true ribs to the sternum
- Permit expansion and recoil of the thoracic cage during respiration
- Stabilize the rib cage while allowing flexibility
Innervation
- Branches of the intercostal nerves (T1–T7)
Clinical Relevance
- Costochondritis: Inflammation of the costal cartilage and sternocostal joint, causing anterior chest pain
- Sternal dislocation: Trauma may displace costal cartilages at the sternum, especially in the 2nd or 3rd joints
- Arthritis: Sternocostal joints, especially the 2nd, may be involved in inflammatory arthropathies
- Surgical significance: Joints may be encountered or divided during sternotomy or thoracic surgeries
Last updated on May 5, 2025