An ulnar nerve block is the production of local anaesthesia in the distribution of the ulnar nerve at the wrist.
Less than 5ml of 1% lignocaine is injected beneath the border of flexor carpi ulnaris at the level of the proximal wrist crease. The tendon is the most prominent on the ulnar side of the supinated forearm with the hand flexed. It may be necessary to advance the needle 1.0 to 1.5 cm before the correct position is attained and paraesthesia is felt.
As with all nerve blocks, the dangers are intravascular injection - aspirate regularly - and neural injection.