Shoulder Girdle

  • Shoulder (Pectoral) Girdle: Attachment for upper limbs to trunk

    • Bones of the shoulder girdle: Scapula and Clavicle

  • Glenohumeral Joint: Scapula & humerus

  • Key Bony Landmarks:

    • Manubrium

    • Clavicle

      • Acromial end

      • Sternal end

      • Act as a brace to hold shoulder girdle/arms away from thorax

      • Curved shape  fractures anteriorly

    • Coracoid process

    • Acromion process

    • Glenoid fossa

    • Lateral border

    • Inferior angle

    • Medial border

    • Superior angle

    • Spine of the scapula (aka: scapular spine)

  • Joints and Joint Movements 

    • Sternoclavicular (SC) Joint: Diarthrodial/synovial joint (arthrodial); multiaxial

      • Movements: anteriorly 15º (protraction); posteriorly 15º (retraction); superiorly 45º (elevation); inferiorly 5º  (depression); slight rotary movement at SC joint

      • Anterior: sternoclavicular ligament

      • Posterior: sternoclavicular ligament

      • Costoclavicular & interclavicular ligaments provide stability against superior displacement

    • Acromioclavicular  (AC) Joint: Coracoclavicular joint:  syndesmotic-type joint to enhance the stability of AC joint 

      • Coraclavicular ligaments

      • Acromioclavicular ligaments

      • Often injured

    • . Scapulothoracic  Joint: Lacks ligamentous support but supported dynamically by its muscles

      • Movements: 25º abduction-adduction; 60º upward-downward rotation; 55º elevation-depression

    • Abduction (protraction): scapula moves laterally away from spinal column

    • Adduction (retraction): scapula moves medially toward spinal column

    • Depression: downward or inferior movement

    • Elevation: upward or superior movement, as in shrugging shoulders

    • Downward rotation:moving inferior angle inferomedially toward spinal column & glenoid fossa downward

    • Upward rotation: turning glenoid fossa upward & moving inferior angle superolaterally away from spinal column

    • Lateral tilt (outward tilt): during abduction; scapula rotates about its vertical (“long”) axis resulting in posterior movement of medial border & anterior movement of lateral border

    • Medial tilt (inward tilt): during extreme adduction; scapula rotates about its vertical axis resulting in anterior movement of medial border & posterior movement of lateral border

    • Anterior tilt (upward tilt): rotational movement of scapula about lateral/frontal axis occurring during glenohumeral hyperextension; superior border moving anteroinferiorly & inferior angle moving posterosuperiorly

    • Posterior tilt (downward tilt):rotational movement of scapula about lateral/frontal axis occurring during glenohumeral hyperflexion; superior border moving posteroinferiorly & inferior angle moving anterosuperiorly 

    • Shoulder girdle muscles: synergy with muscles of glenohumeral joint

      • Muscles of the shoulder girdle contract to maintain scapula in a relatively static position during shoulder joint actions

      • Muscles of the shoulder girdle contract to move shoulder girdle & enhance movement of upper extremity

  • Shoulder girdle movements = scapula movements

  • Shoulder joint & shoulder girdle work together in carrying out upper extremity activities

  • Shoulder Girdle: Musculature

    • Trapezius: upper, middle, lower portions

      • Upper fibers: elevation of scapula, extension & rotation of head

      • Middle fibers: elevation, upward rotation & adduction

      • Lower fibers: depression, adduction & upward rotation

    • Rhomboids – deep: Major, minor

      • Rhomboid major & minor muscles work together

      • Adduction (retraction): draw scapula toward spinal column

      • Downward rotation: from upward rotated position they draw scapula into downward rotation

      • Elevation: slight upward movement accompanying adduction

    • Levator scapula

      • Elevates the medial margin of the scapula

      • Weak downward rotation

      • Weak adduction

    • Serratus anterior

      • Abduction (protraction): draws medial border of scapula away from vertebrae

      • Upward rotation: longer, lower fibers tend to draw inferior angle of scapula farther away from vertebrae, thus rotating scapula upward slightly

    • Pectoralis minor – deep

      • Abduction (protraction): draws scapula forward & tends to tilt lower border away from ribs

      • Downward rotation: as it abducts, it draws scapula downward

      • Depression: when scapula is rotated upward, it assists in depression

  • Aggregate Muscle Actions: Scapular Abduction

    • Scapula moves laterally away from vertebral column without rotation

    • Examples: push-ups, bench press

    • Agonists: Pectoralis minor; Serratus anterior

  • Aggregate Muscle Actions: Scapular Adduction

    • Return from abduction

    • Occurs with retractions

    • Agonists: Trapezius (Middle, lower fibers; Rhomboids

  • Aggregate Muscle Actions: Scapula Upward Rotation

    • Lateral & upward movement

    • Agonists: Trapezius (Middle, lower fibers) Serratus anterior

  • Aggregate Muscle Actions: Scapula Downward Rotation

    • Glenoid fossa is rotated downward when downward movement of shoulder joint occurs

    • Example: Lat Pulls

    • Agonists: Pectoralis minor; Rhomboids

  • Aggregate Muscle Actions:Scapula Elevation

    • Lifting scapula without rotation in anatomic position

    • Example: shoulder shrug

    • Agonists: Levator scapula; Trapezius (upper fibers); Rhomboids

  • Aggregate Muscle Actions: Scapula Depression

    • Agonists: Trapezius; Lower fibers; Pectoralis minor