Ultrasound Anatomy of the Radial Nerve in the Distal Upper Arm

Points B and C may represent convenient, novel sites for ultrasound-guided radial-nerve block. The nerve is clearly visualized and has not yet divided into superficial and deep branches. Point C may be the optimal site for radial-nerve block because of the smaller risk of vessel puncture. Our observations also demonstrate the ability of ultrasound to identify nerves at sites not clearly defined by surface anatomic landmarks.