Upper limb nerve blocks

Brachial plexus blockade has enjoyed great popularity since it was first reported in 1884. As the ventral primary rami of cervical nerves 5–8 and a part of the first thoracic nerve emerge from the intervertebral foramina, they are invested in a fascial sheath that runs to a point distal to the axilla. Effective regional anaesthesia can be achieved with single or multiple injections at a variety of levels of this sheath. The volume and concentration of the local anaesthetic play a crucial role in determining the outcome of the block. A thorough knowledge of the anatomy of the brachial plexus (see page 109) and the relevant surrounding structures is paramount to ensure safe and successful regional anaesthesia of the arm. The anatomy described on page 109 is a classical layout, but seven major variations have been outlined and most people show significant left/right assymetry. Two areas of the arm are not supplied by nerves from the brachial plexus; branches of the superficial cervical plexus supply the skin on the shoulder, and the posteromedial aspect of the arm is innervated by the intercostobrachial nerve. This is of clinical relevance because the latter may need to be blocked to prevent tourniquet pain.