Exposure of left subclan aery by supraclavicular approach does NOT require cutting of?

Exposure of left subclan aery by supraclavicular approach require incision of sternomastoid, omohyoid and scalenus anterior muscle. Supraclavicular incision one finger breadth above the clavicle allows excellent exposure of the middle and distal subclan aery.Right subclan aery is a branch of the brachiocephalic trunk and begins behind the right sternoclavicular joint. Left subclan aery is a direct branch of aoa. The subclan aery is divided into three pas in relation to the anterior scalene muscle: proximal, middle and distal. Proximal subclan aery gives rise to veebral, internal thoracic and thyrocervical trunk. Middle subclan aery contains costocervical trunk and the dorsal scapular aery. Distal subclan aery has no branches.