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Scapula

SCAPULA


SCAPULA

  • Flat triangular bone overlapping second to seventh rib of the upper part of posterolateral chest wall.
  • Important features are:
  1. Inferior angle overlaps seventh rib or seventh intercostal space & lies opposite to tip of T7 spinous process.
  2. Superior angle lies opposite to tip of T2 spinous process.
  3. Lateral angle corresponds to glenoid fossa.
  4. Junction of medial (vertebral) border corresponds to tip of T3 spine.
  • The medial border, inferior angle and part of the lateral border of scapula can be palpated on a patient as can the spine and acromian.
  • The superior border and angle of the scapula are deep to soft tissue and are not readly palpable.
  • Triangle of Auscultation bounded by trapezius, lattismus dorsi and medial border of scapula, lies just medial to lower half of medial border.
  • Congenital high scapula is known as sprengel’s deformity. It is due to failure of normal descent of scapula during development.
 
MUSCLES ATTACHED TO SCAPULA:
 
  1. Coracoid process:  Tip of the coracoid process gives origin to coracobrachialis (medially) and short head of the biceps laterally.  The upper surface receives insertion of pectoralis minor.
  2. Spine of scapula and acromian process: There is origin of Deltoid and insertion of trapezius.
  3. Glenoid tubercle:  Supraglenoid tubercle gives origin to the long head of biceps and infra glenoid tubercle gives origin to long head of triceps.
  4. Lateral border:  Origins of teres minor & teres major.
  5. Medial border: Insertion of serratus anterior (anteriorly); & rhomboideus major, rhomboideus minor & levator scapulae (posteriorly).
  6. Costal (anterior) surface (origin): Subscapularis.
  7. Dorsal surface (origins): Supraspinatus, infraspinatus and at inferior angle latissimus dorsi.
 
 
MOVEMENTS OF SCAPULA:
 

MOVEMENTS OF SCAPULA

MUSCLES CAUSING MOVEMENTS

Elevation

  • Trapezius (upper part)
  • Levator scapulae

Depression

  • Pectoralis minor
  • Serratus anterior

Protraction

  • Serratus anterior
  • Pectoralis minor

Retraction

  • Rhomboideus major
  • Rhomboideus minor
  • Trapezius

Forward rotation of inferior    angle (for overhead abduction)

  • Trapezius (upper fibers)
  • Serratus anterior (lower fibers)

Backward rotation

  • Levator scapulae
  • Rhomboideus major & minor

 

Exam Question

  • Congenital elevation of scapula is called Sprengel shoulder.
  • Winging of scapula is seen in paralysis of Serratus anterior muscle.
  • Superior angle of scapula lies at T2 level.
  • Inferior angle of scapula lies at T7.
  • Superior border of scapula is non palpable.
  • Protractor of scapula is Serratus anterior.
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