The Brachial Plexus and The Anterior Scalene Muscle: A Bilaterally Different Variation and Its Clinical Significance

Abstract

PURPOSE Anatomical variations of the brachial plexus (BP) are revealed in clinical practice and affect the pathogenesis of certain illnesses, including thoracic outlet syndrome (TOS), brachial plexus block anesthesia, and brachial plexus injuries. While the possibility of BP variations is high, bilaterally different variations are rare. METHODS A variation of the BP was observed during dissection of a 49-year-old female cadaver. The body was placed in a supine position and the root of the neck was exposed after removing the skin, superficial fascia, sternocleidomastoid muscle, clavicle and omohyoid muscle in turn. RESULTS This report presents a case of a bilateral variation of the 5th cervical nerve (C5) and its relation to the anterior scalene muscle (ASM). The left 5th cervical nerve passes anterior to the left anterior scalene muscle, while the right 5th cervical nerve penetrates through the right anterior scalene muscle. CONCLUSION Herein, this case report, accompanied by photographs of an actual cadaver, can help clinicians understand TOS, optimize the brachial plexus block procedure, and manage BP injuries better.