The presence of anatomical variations of the peripheral nervous system often accounts for unexpected clinical signs and symptoms. We report unusual variations of the lateral and posterior cords of the brachial plexus in a female cadaver. Such variations are attributed to a faulty union of divisions of the brachial plexus during the embryonic period. The median nerve lay medial to the axillary artery (AA) on both sides. On the right, the lateral root of the median nerve crossing the AA and the median nerve in relation to the medial side of the AA was likely the result of a faulty development of the seventh intersegmental artery. We discuss these variations and compare them with the findings of other researchers. Knowledge of such rare variations is clinically important, aiding radiologists, anaesthesiologists and surgeons to avoid inadvertent damage to nerves and the AA during blocks and surgical interventions.
Axillary Artery ; innervation ; Brachial Plexus ; abnormalities ; anatomy & histology ; Cadaver ; Female ; Human Body ; Humans ; Median Nerve ; abnormalities ; anatomy & histology ; Middle Aged

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 90degrees, the shoulder externally rotated, and the forearm flexed by 90degrees 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.
Anatomy, Cross-Sectional ; Anesthesia, Conduction ; Arm ; Arteries ; Axilla ; Axillary Artery ; Axillary Vein ; Brachial Plexus* ; Elbow ; Forearm ; Humans ; Musculocutaneous Nerve ; Shoulder ; Supine Position ; Ultrasonography* ; Veins

The superficial brachial artery (SBA), a branch of the axillary artery, is one of the most common arterial variations in this area. While it is more vulnerable to accidental arterial injection or injury, it could be useful for the nourishment of a medial arm skin free flap. To analyze the relationship between the SBA of axillary origin and segmental variation of the axillary artery, we dissected 304 arms of Korean cadavers. We found an SBA of axillary origin in 12.2% of cadaveric arms. Unilateral occurrence was detected in 16 cadavers and bilateral in 10. SBAs gave rise to radial and ulnar arteries in the cubital fossa (8.9%), continued in the forearm as the radial artery (2.3%), or ended in the upper arm (1.0%). The SBA ended as ulnar artery was not found in any of the cadavers. The bifurcation of the SBA into the radial and ulnar arteries, presence of an SBA that ends in the upper arm, and the lack of continuation as the ulnar artery are characteristics of SBAs in Korean cadavers.
Arm/*blood supply ; Axillary Artery/anatomy & histology ; Brachial Artery/*anatomy & histology/*physiology ; Cadaver ; Female ; Humans ; Korea ; Male ; Median Nerve/blood supply ; Models, Anatomic ; Radial Artery/anatomy & histology ; Ulnar Artery/anatomy & histology