Infraclavicular brachial plexus blocks

Successful brachial plexus block requires a thorough knowledge of anatomy, both to decide on the appropriate approach and to locate the nerves. The plexus is traditionally found at specific anatomical points by using bony or vascular landmarks, whereas ultrasound allows block of the plexus at any point along its length. The course of the brachial plexus and its relationship to nearby structures is shown in Figure 1. Divisions are formed at the outer border of the first rib and then join to create cords. These can be blocked from below the clavicle as an infraclavicular block (ICB) or from the axilla as axillary block. As the plexus emerges below the clavicle approximately at its midpoint, it initially runs laterally between the clavicle (cephalad) and the artery (caudally) where it can be blocked by the vertical ICB. As it passes laterally, the plexus changes to sit cephalo-laterally to the artery and then wraps around the artery to assume its true anatomical position in the axilla with the cords lying lateral, posterior, and medial to the axillary artery. The boundaries of the infraclavicular fossa are the pectoralis minor and major muscles anteriorly, ribs and intercostal muscles medially, clavicle and coracoid process superiorly, and the humerus laterally.