The primary ventral rami of C5 and C6 unite to form the upper trunk above the subclavian artery, C7 becomes the middle trunk and C8 and T1 unite to form the lower trunk. Both the brachial plexus and the subclavian artery lie on top of the first rib. The brachial plexus is located lateral and posterior to the subclavian artery. The subclavian vein and anterior scalene muscle are found medial to the subclavian artery. The pleura is usually found within 1-2 cm from the brachial plexus.
The supraclavicular approach to the brachial plexus at the level of the nerve trunks or divisions was first described by Kulenkampf. However, the original technique was associated with a high incidence of pneumothorax. Although subsequent modification of this technique has lowered the complication rate, performance of this block without visual guidance is generally not recommended for outpatients.
