Anatomy
Origin:
Spinous processes of T2 to T5.
Insertion:
Medial border of the scapula between the spine and the inferior angle, inferior to the attachment of rhomboid minor.
Key Relations:
-Inferior to rhomboid minor.
-Posterior to trapezius except at the triangle of auscultation.
Functions
-Retracts the scapula e.g. pulling open a drawer.
-Working with the levator scapulae and pectoralis minor, rotates the scapula depressing the glenoid cavity.
-Also stabilizes the scapula to the thoracic wall.
Supply
Nerve Supply:
Dorsal scapular nerve (C4, C5).
Blood Supply:
-Dorsal scapular artery
-Dorsal perforating branches of the upper 5-6 posterior intercostal arteries.
Clinical
As the scapula does not have a bony attachment to the torso, it is stabilized by muscles such as rhomboid major attached between its medial border and the spine. Damage to rhomboid major can therefore cause scapular instability.
Rhomboid major can be tested clinically by gross observation. If function is decreased, the scapula on the affected side may lie more lateral than the scapula of the fully functioning side.
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