Abstract:

Objective To perform an anatomic examination to describe the locations and variations of 4 main nerves around the axillary artery using ultrasound guidance and electrical stimulation, and to provide a basement for the upper limb nerve block. Methods 167 patients undergoing axillary brachial plexus block from December 2007 to March 2009 in Department of Hand Surgery of Beijing Jishuitan Hospital were selected.The probe was placed at the intersection between pectoralis major muscle and biceps muscle.The axillary artery, the ulnar, radial, median, and musculocutaneous nerves were identified.The location of each nerve in the neurovascular bundle was recorded by subdividing the bundle into four-chart sectors with the artery in the center. Results The median, ulnar, and radial nerves proceed clockwise around the axillary artery in the neurovascular bundle.At this level, the median nerve could be found most often (83.8%) in quadrant Ⅳ(both anterior and lateral to the axillary artery).The most common position (72.5%) of the ulnar nerve was found in quadrant Ⅰ(anterior medial to the axillary artery), the radial nerve could be found most often (61.7%) in quadrant Ⅱ(medial posterior to the axillary artery).In most patients(89.2%), the musculocutaneous nerve was lined in a fascial plane between the coracobrachialis muscle and the biceps muscle, but there were a few patients showed a musculocutaneous nerve variation which lied in the neurovascular bundle, lateral to the axillary artery. There were still 8 cases which musculocutaneous nerves were not found in the axilla.The distances from skin surface to the center of musculocutaneous, radial, median and ulnar nerves were (1.58±0.59)cm, (1.33±0.69)cm, (0.62 ±0.13)cm and (0.59±0.22)cm, respectively;there was no difference in the depth between median and ulnar nerves(P>0.05), but there were significant differences in the depth between any other two nerves(P<0.05).There were two veins in axillary sheat in 47.3% persons of all 167 patients, the average was(2.4±0.8). Conclusion The median, ulnar, and radial nerves proceed clockwise around the axillary artery in the neurovascular bundle with high variation, and the musculocutaneous nerve is blocked separately within the coracobrachialis muscle.There are many veins around the axillary artery.

Key words: ultrasound-guidance, nerve stimulation, brachial plexus, axillary block, neuro anatomy