The branches of the subclavian arteries Three parts:by the anterior scalene muscle .1st part:medial to the muscle .2nd part:posterior to the muscle .3rd part:lateral to the muscle anterior scaleneThe branches of the subclavian arteries Three parts: by the anterior scalene muscle •1st part: medial to the muscle •2 nd part: posterior to the muscle •3 rd part: lateral to the muscle anterior scalene