Anatomical study of the brachial plexus using surface ultrasound.

The aim of this study was to define the anatomy relevant to brachial plexus regional anaesthesia and to identify the extent of variation between individuals. Surface ultrasound examination of the brachial plexus was performed on twenty volunteers. In the axilla there was considerable individual variation in the location of the median, radial and ulnar nerves in relation to the axillary artery. There was often more than one venous structure in this region, which was easily compressed by surface palpation. In the supraclavicular region, neural elements were located inferiorly to the subclavian artery in two volunteers. In one volunteer, a vein was identified between nerve trunks in the interscalene region. These findings indicate that the anatomical variation is considerable, even within the relatively small sample studied. For this reason, use of surface ultrasound may lead to increased success of brachial plexus regional anaesthesia and a decreased risk of intravascular injection.