 Block prosedures All the brachial plexus blocks were performed by the same anesthesiologist. The patient is made comfortable in supine position with the arm abducted and the elbow flexed to 90 degrees. After skin and probe preparation, A linear US probe HFL 38, 6-13MHz was placed in the transverse plane at the lateral border of pectoralis major muscle to obtain the best view of the brachial plexus. Image quality is optimised with selection of appropriate depth within 2 cm, focus range within 1cm and gain. The structures of interest are very superficial with the pulsating axillary artery localised within 1 cm . Surrounding the axillary artery, one will find the three out of four terminal branches of the brachial plexus: the median superficial and lateral to the artery, the ulnar superficial and medial to the artery and the radial posterior and lateral or medial to the artery nerves. A 5 cm needle 21G, Locoplex, Vygon, Ecouen, France is inserted parallel to the long axis of the transducer from the lateral side. As the needle is in the same plane as an ultrasound beam, the path of the advancement can be visualised in real time as the needle approaches the target nerves. Ideally, the radial nerve should be targeted first, as it lies posterior to artery, in order to prevent displacing the structures of interest to deeper and obscuring the median and ulnar nerves. The musculocutaneous nerve was blocked separately outside the neurovascular bundle with 3 ml 0.5 bupivacaine at all of the patient. We were also worried about the nerve puncture or intraneural injection. In addition, we also confirmed that the location of the needle tip was not in hypoechoic area before each injection. For further safety, we injected 0.5 ml of local anesthetic as a test dose. If the patients complained of paresthesia or pain, or the injection pressure was high, or the spread of local anesthetic was not visualized, investigastors stopped injection, and withdrew the needles and tried again. The investigastors regarded the paresthesia or pain, or high injection pressure as intraneural injection. 