Osteology of the Clavicle

Introduction

• This is the first video in an astrology series on the Jung-Hwa podcast.
• Focus on the clavicle: its parts, muscle and ligament attachments, fracture classification, and key points about the bone.

Key Characteristics of the Clavicle

• First bone to ossify: Sternal end is the last ossification center to fuse.
• Function: Acts as a strut, bracing the shoulder from the trunk, allowing optimal shoulder function.
• Shape: S-shaped, cylindrical, horizontal in the body.
• Borders and Surfaces:
  • Anterior and posterior borders.
  • Medial (sternal) end: rounded.
  • Lateral (acromion) end: flattened.
  • Superior surface: Smooth and subcutaneous.
  • Inferior surface: Rough with subclavian groove.

Structural Details

• Medial two-thirds:
  • Circular in section, convex anteriorly.
  • Anterior and posterior surfaces instead of borders.
• Lateral one-third:
  • Flattened in section, convex posteriorly.

Articulations and Attachments

• Medial articulations:
  • Manubrium at sternoclavicular joint.
  • First costal cartilage via costoclavicular ligament.
• Lateral articulations:
  • Acromion at acromioclavicular joint.
  • Coracoid process via coracoclavicular ligament.

Muscle Attachments

• Anterior surface of medial one-third: Origin of clavicular head of pectoralis major.
• Posterior surface of medial one-third: Sternocleidomastoid muscle.
• Lateral one-third anterior border: Origin of anterior fibers of deltoid.
• Lateral one-third posterior border: Insertion of trapezius.

Inferior Surface Details

• Medial end: Costoclavicular ligament attached to an oval impression.
• Subclavian groove: Insertion of subclavius muscle.
• Lateral third: Conoid tubercle and trapezoid ridge for coracoclavicular ligaments.

Fractures of the Clavicle

• Commonality: Most common fractured bone.
• Injury Mechanism: Fall on shoulder or outstretched hand.
• Weak Point: Junction of medial two-thirds and lateral one-third.

Fracture Classification

• Based on Location: Proximal, middle, or distal third.
• Allman Classification:
  • Group 1: Middle third (80% of fractures, typically manageable by closed methods).
  • Group 2: Distal third (includes subtypes based on ligament involvement and displacement).
    • Type 1: Minimal displacement with intact ligaments.
    • Type 2: Displaced, medial to coracoclavicular ligaments, higher non-union risk, further subdivided (Type 2a and 2b).
    • Type 3: Articular surface fracture with no ligament injury.
  • Group 3: Proximal third, typically minimally displaced, costoclavicular ligaments remain intact.

Conclusion

• Overview of the clavicle’s osteology essential for viva exams.
• Encouragement to like and subscribe for more content.

Additional Resources

• Follow the Young Orthopod on Facebook and Blogger for more orthopedic content.