Lecture on Shoulder Complex

Introduction

• Shoulder Complex Function: Places hand in position for daily activities.
• Components: Involves structures of axial and appendicular skeleton contributing to upper extremity movement.
  • Regions: Sternum, rib cage, clavicle, scapula, humerus, and joints formed by these structures.

Primary Joints of the Shoulder Complex

1. Sternoclavicular (SC) Joint: Located between the sternum and clavicle.
2. Acromioclavicular (AC) Joint: Located between the acromion of the scapula and the clavicle.
3. Glenohumeral (GH) Joint: Commonly known as the shoulder joint, located between the glenoid fossa and the humerus.
4. Scapulothoracic Articulation: Not a true joint but an articulation surface between the scapula and thoracic cage.

Shoulder Girdle vs. Shoulder Joint

• Shoulder Girdle: Involves the scapula, clavicle, sternum, and rib movements.
  • Joints: SC joint, AC joint, scapulothoracic articulation.
  • Movements: Scapular elevation, depression, protraction, retraction, upward rotation, downward rotation.
• Shoulder Joint: Primarily refers to the glenohumeral joint.
  • Movements: Shoulder flexion, extension, abduction, adduction, internal rotation, external rotation, horizontal abduction, horizontal adduction.

Detailed Joint Analysis

Sternoclavicular (SC) Joint

• Type: Triaxial joint with limited range of motion.
• Structure: Convex shape of clavicle fits into the sternum.
• Ligaments: Provide stability
  • Interclavicular ligament: Connects both clavicles.
  • Sternoclavicular ligament: Connects sternum and clavicle.
  • Costoclavicular ligament: Connects ribs to clavicle.
• Movements: Clavicular elevation, depression, protraction, retraction, rotation.

Acromioclavicular (AC) Joint

• Type: Triaxial joint with limited range of motion.
• Structure: Acromion of scapula forms joint with the clavicle.
• Ligaments: Provide stability
  • Acromioclavicular ligament: Connects clavicle and acromion.
  • Coracoacromial ligament: Connects coracoid process and acromion.
  • Coracoclavicular ligament: Connects coracoid process and clavicle.
• Injury: Susceptible to damage from falls, leading to compromised shoulder movement.

Scapulothoracic Articulation

• Type: Not a true joint, but important for shoulder movement.
• Movements: Scapular elevation, depression, protraction, retraction, upward rotation, downward rotation, scapular tilt (in less common movements).

Importance of Ligaments and Stability

• GH Joint: Ball-and-socket joint, relies on ligaments and muscles to keep the humeral head within the glenoid fossa.
• Stability: Key ligaments in the SC and AC joints provide necessary stability for effective shoulder movement.

Summary

• Key Movements: Understand the six primary movements of the scapula and the range of motion at the SC, AC, and GH joints.
• Structural Importance: Recognize the role of ligaments in maintaining joint stability and their impact on shoulder mobility and injury potential.