Sternoclavicular Joint Anatomy and Dislocations

Sternoclavicular Joint

• Saddle joint, allowing movement in two axes.
• Articular disc provides smooth movement between clavicle and manubrium, enabling rotation and motion in a third axis.
• Strong joint capsule and ligaments, particularly the costoclavicular ligament, contribute to stability.
• Costoclavicular ligament transfers stress from clavicle to manubrium via costal cartilage.
• Dislocation of the sternoclavicular joint is rare and requires significant force.
• Costoclavicular ligament and articular disc effectively absorb and transmit forces away from the joint.
• Two types of dislocations:
  • Anterior dislocations are more common, resulting from blows to the anterior shoulder.
  • Posterior dislocations are caused by forces pushing the shoulder forward or direct impact.
• In younger individuals, the epiphyseal growth plate of the clavicle may be injured, causing a fracture alongside the dislocation.
• The costoclavicular ligament, composed of two parts, attaches to the first rib and the clavicle.
• It is a strong ligament, resisting elevation of the pectoral girdle.
• Sternoclavicular and interclavicular ligaments are thickenings of the joint capsule.

Neurovascular Supply

• The sternoclavicular joint receives blood supply from two arteries:
  • Suprascapular artery, a branch of the thyrocervical trunk.
  • Internal thoracic artery (mammarian artery), a branch of the subclavian artery.
• The joint is innervated by two nerves:
  • Medial supraclavicular nerve (C3 and C4).
  • Subclavius nerve (C5 and C6), innervating the subclavius muscle.

Movements

• Sternoclavicular joint allows for a wide range of motion:
  • Elevation of the shoulders (shrugging)
  • Depression of the shoulders (drooping)
  • Protraction of the shoulders (moving the shoulder girdle anteriorly)
  • Retraction of the shoulders (moving the shoulder girdle posteriorly)
  • Rotation: When the arm is raised, the clavicle rotates passively.
• Costoclavicular ligament acts as a pivot for clavicle movements.

Mobility and Stability

• Sternoclavicular joint is highly mobile to accommodate upper limb movements.
• It provides stability as the only connection between the upper limb and the axial skeleton.

Joint Structure

• The sternoclavicular joint is a saddle-type synovial joint (double-plane joint) between the clavicle and manubrium.
• It is the only attachment of the upper limb to the axial skeleton.
• Despite its strength, it is a very mobile joint.
• Articular surfaces are covered with fibrocartilage.

Articular Disc

• Fibrocartilaginous articular disc separates the joint into two compartments.
• Similar to the temporomandibular joint.

Fibrocartilage

• Consists of white fibrous tissue and cartilaginous tissue.
• Tough, flexible, and elastic due to its composition.
• Contains type I collagen in addition to type II.

Explore the anatomy and mechanics of the sternoclavicular joint, a saddle joint that allows movement in multiple axes. Learn about its stability, the role of the costoclavicular ligament, and the types of dislocations that can occur. This quiz covers essential points about joint movement and potential injuries.