Lecture Notes: Shoulder Complex and Rotator Cuff Muscles

Rotator Cuff Muscles

• Definition: Group of four muscles that stabilize the GH (glenohumeral) joint.
• Muscles Involved:
  • Supraspinatus: Located at the top of the shoulder blade.
  • Infraspinatus: Located below the supraspinatus.
  • Teres Minor: Located near the shoulder blade.
  • Subscapularis: Located in the front of the shoulder blade.
• Mnemonic: S.I.T.S (Supraspinatus, Infraspinatus, Teres Minor, Subscapularis).
• Functions: Each muscle has a specific role in shoulder movement.

Scaption

• Definition: Movement along the scapular plane.
• Scapular Plane: Angle between the thoracic region and the scapula (~30° anterior to the frontal plane).
• Motion: Abduction to about 30° and then raising the arm diagonally.
• Usage: Common in rehabilitation, especially for rotator cuff injuries.
• Importance: Provides a safe and secure motion for shoulder movement.

Shoulder Complex

Components

• Shoulder Girdle: Includes the scapula and clavicle.
• Shoulder Joint: Includes the glenohumeral joint (GH joint).

Range of Motion (ROM) Evaluation

• Combined Movements: Movement involves both shoulder girdle and shoulder joint.
• Evaluation: Ensure both the GH joint and the scapula are functioning properly for full ROM.

Scapulohumeral Rhythm

• Definition: Ratio of movement between the shoulder joint and shoulder girdle, especially during flexion and abduction.
• Ratio: 2:1 (GH joint to scapular movement).
• Details: During 180° shoulder abduction, 120° from GH joint, 60° from scapula (30° from AC joint, 30° from SC joint).

Common Shoulder Pathologies

• Bone Fracture
• Dislocation: Common in stroke patients.
• Impingement Syndrome: Compression between the acromion arch and humeral head.
• Rotator Cuff Tears: Especially common with supraspinatus muscle.
• Bicipital Tendonitis: Inflammation of the biceps long head.

Summary

• The shoulder complex is highly mobile but also prone to injury.
• Important to understand the anatomy and movement of the shoulder for proper diagnosis and rehabilitation.
• Common pathologies include fractures, dislocations, impingement syndrome, and tendonitis.