SCAPULA
SCAPULA
- Flat triangular bone overlapping second to seventh rib of the upper part of posterolateral chest wall.
- Important features are:
- Inferior angle overlaps seventh rib or seventh intercostal space & lies opposite to tip of T7 spinous process.
- Superior angle lies opposite to tip of T2 spinous process.
- Lateral angle corresponds to glenoid fossa.
- 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:
- 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.
- Spine of scapula and acromian process: There is origin of Deltoid and insertion of trapezius.
- Glenoid tubercle: Supraglenoid tubercle gives origin to the long head of biceps and infra glenoid tubercle gives origin to long head of triceps.
- Lateral border: Origins of teres minor & teres major.
- Medial border: Insertion of serratus anterior (anteriorly); & rhomboideus major, rhomboideus minor & levator scapulae (posteriorly).
- Costal (anterior) surface (origin): Subscapularis.
- Dorsal surface (origins): Supraspinatus, infraspinatus and at inferior angle latissimus dorsi.
MOVEMENTS OF SCAPULA:
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MOVEMENTS OF SCAPULA |
MUSCLES CAUSING MOVEMENTS |
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Elevation |
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Depression |
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Protraction |
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Retraction |
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Forward rotation of inferior angle (for overhead abduction) |
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Backward rotation |
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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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