Multiple Unilateral Variations in Brachial Plexus Formation and Its Clinical Correlations

ABSTRACT

The brachial plexus is a complex somatic nerve plexus that innervates the upper limb. Due to its complex developmental pattern, anatomical variations are relatively common. Awareness of these variations is important for anatomists, radiologists, anesthesiologists, and surgeons. During routine dissection of a 65‐year‐old female cadaver, variations in the formation of the brachial plexus on the right side were observed. In this case, the posterior cord does not receive the posterior division of the lower trunk. The inferior trunk did not divide into anterior and posterior divisions, and the anterior division of the middle trunk instead joined the inferior trunk. In other words, the lateral cord is formed solely by the anterior division of the superior trunk. Accordingly, the lateral root of the median nerve is distinctly narrower than its medial root. It is concluded that these variations from standard anatomic structures may not have affected the function of the upper extremity in this individual. However, awareness of the possible existence of such variations may help surgeons reduce the risk of surgical complications and intraoperative oversights.