sternoclavicular joint

• joint classification:

  synovial saddle joint
• axis of movement:

  three degrees of freedom available
• articular surfaces:

  Sternal (medial) end of the clavicle

  • Covered by fibrocartilage

  • Convex superior to inferior

  • Concave anterior to posterior
• Articular Surfaces:

  Clavicular notch of the sternum

  • Covered in hyaline cartilage

  • Reciprocally concavo-convex
• Articular Surfaces:

  Costal cartilage of 1st rib
• Joint Capsule:

  • Fibrous capsule surrounding entire joint

  • Attaching to articular margins of clavicle and sternum

  • Relatively strong (apart from inferiorly)

  • Strengthened capsular thickenings: anterior and posterior sternoclavicular ligaments and interclavicular ligaments
• Intra-articular Disk

  • O: Firmly attached to the upper border of the sternal end of the clavicle

  • I: Costal cartilage of the 1st rib

  Functions:

  • Improves congruency

  • Shock absorption and force dissipation

  • Stabilisation of the s-c joint
• Sternoclavicular ligaments:

  Anterior sternoclavicular ligament

  • O: Medial Clavicle (anterior)

  • I: Runs obliquely downwards and medially to the sternum

  • A: Reinforces anterior aspect of the joint capsule
• Sternoclavicular ligaments:

  Posterior sternoclavicular ligament

  • Mirrors the anterior sternoclavicular ligament on posterior aspect joint

  • Not as strong

  • O: Medial Clavicle (posterior)

  • I: Runs obliquely downwards and medially to the sternum

  • A: Reinforces posterior aspect of the joint capsule
• Sternoclavicular ligaments:

  Interclavicular ligament

  • O: Sternal end of clavicle

  • I: Sternal end of other clavicle

  • A: Strengthens capsule superiorly
• Sternoclavicular ligaments:

  Costoclavicular ligament

  • Very strong, extra-capsular ligament

  • O: Inferior surface of medial clavicle (roughened area)

  • I: Costal cartilage of 1st rib

  • A: Limit elevation of clavicle, and to prevent excess ant/post movement of medial end of clavicle
• Scapular Elevation and Depression:

  Elevation: scapula gliding upwards (shrugging)

  Depression: scapula gliding downwards

  Linear range of the scapula is about 10 to 12 cm up and down
• Scapular elevation:

  • Clavicle rolls superiorly, glides inferiorly

  • Movement: about a sagittal (AP) axis

  • ROM: 60 (total range elevation and depression)

  • Limited by: tension in costoclavicular ligament and subclavius
• Scapular depression:

  • Clavicle rolls inferiorly, glides superiorly

  • ROM: 60 (total range elevation and depression)

  • Limited by: interclavicular ligament and intra-articular disc
• Scapular protraction:

  • Clavicle glides posteriorly (vertical axis of movement through costoclavicular ligament)

  • ROM: 35° (total range protraction and retraction)

  • Limited by: costoclavicular and posterior SC ligaments
• Scapular retraction:

  • Clavicle glides anteriorly

  • ROM: 35 (total range protraction and retraction)

  • Limited by: costoclavicular and anterior SC ligaments
• Scapular Lateral Rotation:

  Lateral (upward) rotation

  • Glenoid fossa turns upwards (occurs passively as you flex/abduct GH joint, accompanied by scapular elevation)

  • Clavicle rolls superiorly, glides inferiorly

  • ROM: 60 (total range lateral and medial rotation)

  • Limited by: tension in costoclavicular ligament and subclavius
• Scapular medial rotation:

  • Glenoid fossa turns downwards (occurs passively as you extend/adduct GH joint, accompanied by scapular depression)

  • Clavicle rolls inferiorly, glides superiorly

  • ROM: 60 (total range lateral and medial rotation)

  • Limited by: interclavicular ligament and intraarticular disc