Sternoclavicular Joint

Question 1

Type of Joint

Answer 1

Synovial saddle with an intra-articular disc that acts as a shock absorber and reduces friction, capable of 3 degrees of freedom

• elevation/depression (frontal plane)
• protraction/retraction (transverse plane)
• axial rotation (sagittal plane)

Between med end of clavicle and superolateral angle of manubriumof sternum and adjacent part of 1st costal cartilage
-larger clavicular art surface so clavicle projects above manubrium
Only joint between upper limb and axial skeleton

Question 2

Articular Surfaces

Answer 2

All covered in fibrocartilage
Reciprocally concavoconvex but of different radii of curvature
-congruence improved by fibrocartilaginous intra-artic disc

Clavicular surface convex vert and flattened/slightly concave horizontally
Sternal surface 45deg to vert, concave and convex from different angles

Question 3

Supporting Ligaments

Answer 3

Ant/post Sternoclavicular- reinforces capsule, limits ant/post translation of clavicle (ant is strongest)

• from sup ant/post aspects of sternal end of clavicle
• to ant/post sup aspect of manubrium

Costoclavicular (extracapsular)- limits elevation of shoulder girdle, acts as fulcrum for elev/dep, protrac/retrac and checks clavicular elev and sup glide of clavicle

• Ant lamina: lat from first rib to clavicle
• Post lamina: med from first rib to clavicle

Interclavicular- strengthens capsule superiorly, resists excessive dep/downward glide of clavicle
-from sternal end of one clavicle to sternal end of the other