Fig. 1

a Ultrasound image of the brachial plexus at the CCS. The three cords of the brachial plexus are clustered together lateral to the AA, which shares a consistent relation with the AA. b Ultrasound image of the brachial plexus block at the CCS. The needle tip is placed at the centre of the nerve cluster by advancing the needle through the gap between the LC and PC and advancing it towards the MC. Ropivacaine is injected at the centre of the nerve cluster and surrounds the 3 cords as a local anaesthetic AA, axillary artery; AV, axillary vein; LC, lateral cord; MC, medial cord; PC, posterior cord; R2, second rib; LA, local anaesthetic; CCS: costoclavicular space