Abstract
<title>Abstract</title> <p> <bold>Purpose:</bold> The medial brachial cutaneous nerve (MBCN) and medial antebrachial cutaneous nerve (MACN) typically arise independently from the medial cord of the brachial plexus. We describe a compound variation combining a shared origin directly from the inferior trunk with a distinct distal branching pattern, resulting in potential clinical relevance at two different anatomical sites. <bold>Methods:</bold> The variation was identified during routine dissection of the right upper limb of an 85-year-old formalin-fixed male cadaver. Morphometric measurements were independently repeated by two investigators using a digital caliper and subsequently averaged. <bold>Results:</bold> A common MBCN-MACN trunk arose directly from the inferior trunk in the supraclavicular region. It measured 9.6 cm in length and 5.1 mm in external width at its origin, compared with 4.9 mm for the ipsilateral ulnar nerve. The trunk descended alongside the inferior trunk and medial cord before dividing at the inferior border of the pectoralis minor into the MACN and a short MBCN stem. The MBCN divided into two cutaneous branches, whereas the MACN formed anterior and posterior branches that pierced the deep brachial fascia and subsequently divided into four branches. One secondary posterior branch coursed directly on the surface of the basilic vein and crossed it anteriorly. <bold>Conclusion:</bold> This variation may be clinically relevant in two distinct regions. Proximally, its unexpected origin and substantial caliber may affect supraclavicular procedures and electrodiagnostic localization. Distally, its four-branch configuration and intimate relationship with the basilic vein may increase susceptibility to injury during venous access and surgery around the medial elbow. </p>