Figure 7

In the posterior subscapular approach, the trapezius muscle rhomboideus minor and major muscles are divided longitudinally away from their nerve supply. The anterior plane of dissection is developed by disinserting the levator scapulae, the posterior and middle scalene muscles and retracting them anteriorly and superiorly (anterior black arrow); this provides only limited exposure to the brachial plexus. The posterior plane of dissection is developed by medial retraction of the paraspinal muscles (posterior black arrow). The latter muscles are too bulky to be retracted medially adequately. Besides, medial retraction damages their nerve and vascular supply.