Topographic pattern of the brachial plexus at the axillary fossa through real-time ultrasonography in Koreans

Abstract

Background: The ability to explore the anatomy has improved our appreciation of the brachial anatomy and the quality of regional anesthesia. Using real-time ultrasonography, we investigated the cross-sectional anatomy of the brachial plexus and of vessels at the axillary fossa in Koreans.

Methods: One hundred and thirty-one patients scheduled to undergo surgery in the region below the elbow were enrolled after giving their informed written consent. Using the 5-12 MHz linear probe of an ultrasound system, we examined cross-sectional images of the brachial plexus in the supine position with the arm abducted by 90°, the shoulder externally rotated, and the forearm flexed by 90° at the axillary fossa. The results of the nerve positions were expressed on a 12-section pie chart and the numbers of arteries and veins were reported.

Results: Applying gentle pressure to prevent vein collapse, the positions of the nerves changed easily and showed a clockwise order around the axillary artery (AA). The most frequent positions were observed in the 10-11 section (79.2%) for the median, 1-2 section (79.3%) for the ulnar, 3-5 section (78.4%) for the radial, and 8-9 section (86.9%) for the musculocutaneous nerve. We also noted anatomical variations consisting of double arteries (9.2%) and multiple axillary veins (87%).

Conclusions: Using real-time ultrasonography, we found that the anatomical pattern of the major nerves in Koreans was about 80% of the frequent position of individual nerves, 90.8% of the single AA, and 87% of multiple veins around the AA.

Keywords: Anatomy; Axilla; Brachial plexus; Ultrasonography.

Fig. 1

Schematic illustration of cross-section ultrasound scan image with ultrasound probe placed at the axillary fossa. AA: axillary artery.

Fig. 2

Positions of the individual nerves observed in clockwise order around the AA using ultrasonography in 131 Koreans. AA: axillary artery, AV: axillary vein, M: median nerve, U: ulnar nerve, R: radial nerve, MC: musculocutaneous nerve.

Fig. 3

Schematic representation of common arrangements of the four individual nerves of the brachial plexus as confirmed by ultrasonography in 131 Koreans. AA: axillary artery, AV: axillary vein, M: median nerve, U: ulnar nerve, R: radial nerve, MC: musculocutaneous nerve.

Fig. 4

Axillary vascular variations as confirmed by cross-sectional ultrasound scan image at the axillary fossa. (A) multiple axillary veins, (B) double axillary arteries. AA: axillary artery, AV: axillary vein.