kin part 2 (- ch 6:elbow)

• Shoulder Girdle


  • Entire upper extremity depends upon it to serve as a base from which to function
• Shoulder Girdle Bones


  • Scapula
  • Clavicle
• Shoulder Girdle Bones


  • Move as a unit
  • Clavicle's articulation with the sternum is only bony link to axial skeleton
• Shoulder Girdle Bony Landmarks


  • Manubrium
  • Clavicle
  • Coracoid process
  • Acromion process
  • Glenoid fossa
  • Lateral border
  • Medial border
  • Inferior angle
  • Superior angle
  • Spine of scapula
• Shoulder Girdle Joints


  • Sternoclavicular (SC)
  • Acromioclavicular (AC)
  • Scapulathoracic
• Sternoclavicular (SC)


  Classification: (multiaxial) arthrodial (gliding) saddle
• Sternoclavicular (SC) joint


  • Anteriorly supported by the anterior SC ligament
  • Posteriorly supported by the posterior SC ligament
  • Costoclavicular and interclavicular ligaments provide stability against superior displacement
• Acromioclavicular (AC) joint


  • Arthrodial (gliding) joint
  • Supported by coracoclavicular ligaments (conoid and trapezoid)
  • Supported by superior acromioclavicular and inferior acromioclavicular ligament
  • *One of the most common injury area in girdle*
• Scapulothoracic Joint


  Not a true synovial joint
• Scapulothoracic Joint


  • Movements depend on SC and AC joints which allow scapula to move
  • 25° abduction-adduction (protraction-retraction)
  • 60° upward-downward rotation
  • 55° elevation-depression
  • No ligament support; supported dynamically by its muscles
• Shoulder girdle movements


  • Focus on bony landmarks; inferior angle, glenoid fossa, acromion process
  • All movements have a common pivot point at SC joint
• Shoulder girdle movements


  Scapula movements; wherever the scapula goes, the clavicle follows, vice versa
• Abduction (protraction)SG


  Scapula moves laterally away from spinal column
• Adduction (retraction)SG


  Scapula moves medially toward spinal column
• Upward rotationSG


  Turning glenoid fossa upward and moving inferior angle supero-laterally away from spinal column to assist in raising the arm
• Downward rotationSG


  Returning inferior angle infero-medially toward spinal column and glenoid fossa to normal position
• Elevation SG


  Upward movement of scapula, shrugging shoulders
• DepressionSG


  Downward movement of scapula to normal position
• For some shoulder girdle movements, scapula must rotate or tilt on its axis
• Lateral tilt (internal rotation)SG


  1. During abduction

  2. Posterior movement of medial border

  3. Anterior movement of lateral border
• Medial tilt (external rotation)SG


  1. During extreme adduction

  2. Anterior movement of medial border

  3. Posterior movement of lateral border
• Anterior tilt (upward tilt)SG


  1. During glenohumeral hyperextension

  2. Superior border moving antero-inferiorly

  3. Inferior angle moving postero-superiorly
• Posterior tilt (downward tilt)SG


  1. During glenohumeral hyperflexion

  2. Superior border moving posteroinferiorly

  3. Inferior angle moving antero-superiorly
• Shoulder girdle muscles


  • Stabilize scapula so the shoulder joint muscles will have a stable base form which to exert force moving the humerus
  • Contract to maintain scapula to a relatively static position during shoulder joint action
  • Contract to move shoulder girdle and to enhance movement of upper extremity when shoulder goes through extreme ranges of motion
• Shoulder joint and shoulder girdle


  • Work together in carrying out upper extremity activities
• Shoulder girdle muscles


  • Essential in providing a scapula-stabilizing effect = stable base for powerful movement of humerus at shoulder joint
• As shoulder joint goes through more extreme ROM


  Scapular muscles move shoulder girdle so that its glenoid fossa will be in a more appropriate position from which the humerus can move
• Without the scapula movement, the humerus can only be raised into approximately 90-120° of total shoulder abduction and flexion
• Scapula-humeral rhythm

  1:2 ratio; when the arm is abducted 180°, 60° occurs by rotation of the humerus at the shoulder joint
• Primary shoulder girdle muscles


  • Trapezius: upper, middle, lower
  • Rhomboid: deep
  • Levator scapula
  • Serratus anterior
  • Pectoralis minor: deep
• Primary shoulder girdle muscles


  • Originate on axial skeleton and insert on scapula and/or clavicle
  • Do not attach to humerus
  • Do not cause shoulder joint actions
• Primary shoulder girdle muscles


  Essential in providing dynamic stability of the scapula so it can serve as a relative base of support for shoulder joint activities like throwing, batting, and blocking
• Scapula Muscles


  • Important in spinal posture
  • Forward shoulder due to scapula protractors and depression becoming stronger and tighter and retractors becoming weaker
  • Contributes to kyphosis
  • Less functional position for glenohumeral joint
  • Important to maintain lumbar lordotic curve and keep head over trunk in balanced position
  • Good posture enhances easier inspiration
• Scapula Winging


  Relatively rare but can affect normal functional activity of upper extremity
• Scapula Winging


  • Due to a loss of the normal scapular stability that make the inferior border scapula moves medially or laterally
• Medial scapular winging


  More common
• Medial scapular winging


  Serratus anterior muscle weakness
• Medial scapular winging


  Due to injury of the long thoracic nerve
• Lateral scapular winging


  Trapezius and/or rhomboid muscle weakness
• Lateral scapular winging


  Spinal accessory nerve dysfunction