Lecture Notes on Shoulder Complex

Introduction

• Topic: Shoulder complex
• Function: To place the hand in a position for various occupations
• Components: Involves structures of the axial and appendicular skeleton contributing to upper extremity movement

Structures Involved

• Sternum
• Rib cage
• Clavicle
• Scapula
• Humerus
• Joints: Formed by the bony structures

Primary Joints

1. Sternoclavicular Joint (SC Joint)
2. Acromioclavicular Joint (AC Joint)
3. Glenohumeral Joint (GH Joint)
4. Scapulothoracic Articulation

Sternoclavicular Joint (SC Joint)

• Type: Triaxial joint
• Movements: Elevation, depression, protraction, retraction, rotation
• **Ligaments: **
  • Interclavicular ligament
  • Sternoclavicular ligament
  • Costoclavicular ligament
• Function: Contributes to shoulder movement, although range of motion is tiny

Acromioclavicular Joint (AC Joint)

• Type: Triaxial joint
• Ligaments:
  • Acromioclavicular ligament
  • Coracoacromial ligament
  • Coracoclavicular ligament
• Function: Provides stability, susceptible to injury from falls

Glenohumeral Joint (GH Joint)

• Type: Ball and socket joint
• Reliance: Heavily on ligaments and muscles to keep the humeral bone within the glenoid fossa
• Function: Most mobile joint, prone to dislocation

Scapulothoracic Articulation

• Type: Not a true joint, but an articulation surface
• Function: Allows scapula to move on the thoracic cage

Shoulder Girdle vs. Shoulder Joint

• Shoulder Girdle: Involves activities of scapula, clavicle, sternum, and rib
• Shoulder Joint: Involves activities of scapula and humerus
• Joints in Shoulder Girdle:
  • Sternoclavicular joint
  • Acromioclavicular joint
  • Scapulothoracic joint
• Movements of Shoulder Girdle: Elevation, depression, protraction, retraction, upward rotation, downward rotation
• Movements of Shoulder Joint: Flexion, extension, abduction, adduction, external rotation, internal rotation, horizontal abduction, horizontal adduction

Movement Details

Shoulder Girdle Movements

• Scapular Movements:
  • Elevation
  • Depression
  • Protraction (Scapular abduction)
  • Retraction (Scapular adduction)
  • Upward rotation
  • Downward rotation
  • Potential Scapular Tilt during end-range movements

Shoulder Joint Movements

• Glenohumeral Movements:
  • Flexion
  • Extension
  • Abduction
  • Adduction
  • External rotation
  • Internal rotation
  • Horizontal abduction
  • Horizontal adduction

Importance of Ligaments

• Role in Stability: Provide stability to SC and AC joints
• Common Injuries: Ligament injuries can lead to compromised shoulder movement and are hard to diagnose and heal due to constant shoulder use

Summary

• The shoulder complex is intricate, involving multiple joints and ligaments
• Different components contribute to shoulder movement and stability
• Understanding the anatomy and function of each joint is crucial for diagnosing and treating shoulder issues