Sternoclavicular Joint
Type
Saddle type of synovial joint (despite being a ball-and-socket in appearance, the surfaces are reciprocally curved — saddle type).
This is the only bony joint connecting the skeleton of the upper limb to the axial skeleton.
Articular Surfaces
- Medial (sternal) end of the clavicle — convex superoinferiorly, slightly concave anteroposteriorly
- Superolateral angle of the manubrium sterni + adjacent part of 1st costal cartilage — reciprocally curved
Articular surfaces are covered with fibrocartilage.
The medial end of clavicle projects above the manubrium (poor fit), compensated by the articular disc.
Articular Disc
- Fibrocartilaginous disc attached superiorly to the clavicle and inferiorly to the 1st costal cartilage
- Divides the joint into two compartments
- Prevents medial displacement of the clavicle when the weight of the arm depresses the acromial end
Ligaments
| Ligament | Description |
|---|---|
| Anterior sternoclavicular ligament | Reinforces capsule anteriorly |
| Posterior sternoclavicular ligament | Reinforces capsule posteriorly (weaker than anterior) |
| Interclavicular ligament | T-shaped; connects sternal ends of both clavicles; strengthens capsule superiorly |
| Costoclavicular ligament | Anchors inferior surface of sternal clavicle to 1st rib and cartilage; prevents upward movement of medial clavicle |
Blood Supply
- Internal thoracic artery
- Suprascapular artery
Nerve Supply
- Medial supraclavicular nerve
Movements
Movements at the sternoclavicular joint correspond to movements of the lateral end of the clavicle (and scapula):
- Elevation / Depression (occurs in inferolateral compartment)
- Protraction / Retraction (occurs in superomedial compartment)
- Anterior and posterior rotation of clavicle around its long axis — used in overhead movements
Weight Transmission
Weight of the upper limb → scapula → coracoclavicular ligament → clavicle → sternoclavicular joint → sternum. Some weight → 1st rib via costoclavicular ligament.
Clinical Notes
- Dislocation: Rare due to strength of joint. Medial end usually dislocates anteriorly. Backward dislocation is rare, prevented by costoclavicular ligament.
- In individuals under 25 years: Dislocation may involve fracture through epiphyseal plate (epiphysis at sternal end fuses at 23–25 years)
- Clavicle fractures typically occur between the costoclavicular and coracoclavicular ligaments