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Clavicular notch

The clavicular notch is the shallow, oval-shaped articular depression located on the superolateral aspect of the manubrium of the sternum. It forms the sternoclavicular joint (SC joint) by articulating with the medial end of the clavicle. This articulation is essential for upper-limb mobility and transmits forces between the axial and appendicular skeleton.

The notch is covered by hyaline cartilage and contributes to a saddle-type synovial joint, reinforced by strong ligamentous structures. Though small, it plays a crucial biomechanical role by allowing movement in multiple planes, including elevation, depression, protraction, retraction, and axial rotation of the clavicle.

Synonyms

  • Sternal clavicular articular notch

  • Sternoclavicular facet

  • Manubrial clavicular articulation

Location and Structure

  • Position: Superolateral border of the manubrium, one on each side.

  • Shape: Shallow, elongated, and slightly concave vertically with a convex transverse curvature.

  • Articular cartilage: Hyaline cartilage covering the surface that articulates with the medial clavicle.

  • Joint type: Forms part of the saddle-shaped synovial sternoclavicular joint.

  • Associated structures:

    • Intra-articular disc (fibrocartilaginous)

    • SC joint capsule

    • Sternocleidomastoid and sternothyroid attachments nearby (not directly on notch)

Relations

  • Superiorly: Suprasternal (jugular) notch

  • Laterally: Medial end of the clavicle

  • Inferiorly: First costal cartilage articulating with the manubrium

  • Posteriorly: Upper mediastinum and sternohyoid/sternothyroid muscles

  • Anteriorly: Subcutaneous tissues and skin overlying the manubrium

Attachments

  • Capsular attachment: Sternoclavicular joint capsule attaches around the rim of the notch.

  • Ligamentous attachments:

    • Anterior sternoclavicular ligament (anterior surface)

    • Posterior sternoclavicular ligament (posterior surface)

    • Interclavicular ligament (spanning between clavicles superior to notch)

    • Costoclavicular ligament attaches slightly inferior and lateral (not directly on the notch but stabilizes the joint).

  • Articular disc: Fibrocartilaginous disc attaches superiorly to clavicle and inferiorly to manubrium/first rib junction.

Function

  • Acts as the sternal articulation surface for the clavicle.

  • Enables wide range of shoulder girdle movements through the sternoclavicular joint.

  • Helps distribute forces from upper limb to axial skeleton.

  • Provides stability while allowing significant mobility via ligamentous constraints and articular disc.

MRI Appearance

T1-weighted images

  • Manubrial cortex: Low signal (dark).

  • Bone marrow: Bright (fatty marrow signal).

  • Articular cartilage: Smooth intermediate-to-low signal.

  • Joint space: Narrow low-signal cleft between clavicle and notch.

  • SC joint disc: Intermediate signal, slightly darker than marrow.

  • Adjacent soft tissues: Interclavicular ligament and joint capsule appear as thin low-signal bands.

T2-weighted images

  • Cortex: Dark low signal.

  • Marrow: Bright, slightly less intense than on T1.

  • Cartilage surface: Intermediate-to-brightly delineated over manubrial and clavicular surfaces.

  • Joint cavity: Bright due to synovial fluid.

  • Ligaments: Low-signal linear structures.

STIR

  • Cortex: Persistently dark.

  • Bone marrow: Intermediate-to-dark in normal appearance.

  • Joint capsule and ligaments: Low signal.

  • Intra-articular disc: Low-to-intermediate signal.

  • Surrounding soft tissues: Normal tissues remain intermediate or dark.

T1 Fat-Saturated Post-Contrast

  • Normal manubrium and clavicle: Mild homogeneous marrow enhancement.

  • SC joint capsule and disc: Minimal or no enhancement.

  • Ligaments: No enhancement, remain low signal.

  • Periarticular soft tissues: Mild uniform enhancement of synovium if present physiologically.

CT Appearance

Non-Contrast CT

  • Cortex: High-density, sharply defined.

  • Marrow: Lower-density cancellous bone relative to cortex.

  • Articular surfaces: Smooth, shallow concavity of the clavicular notch clearly visualized.

  • Intra-articular disc: Not well visualized but joint space margins appear regular.

  • Ligamentous attachments: Seen indirectly as soft-tissue thickening.

MRI image

clavicular notch coronal MRI image-img-00000-00000

CT image

clavicular notch coronal CT image-img-00000-00000