Unusual lateral cord of the brachial plexus leading to variation of musculocutaneous and median nerves along with high division of the brachial artery and supernumerary bicipital head

Background The brachial plexus is a critical network of nerves that supplies sensory and motor innervation to the upper arm and shoulder extremity. Variations in its structure and function have significant implications for clinical practice. Case presentation This case report details the anatomical dissections of a 95-year-old female donor and an 87-year-old male donor, uncovering distinct variations in the brachial plexus, musculocutaneous nerve, median nerve, biceps brachii, and brachial artery. In both cases, the musculocutaneous nerve was replaced by two smaller nerves originating from an unusually long lateral cord. In contrast, the median nerve was formed from a direct continuation of the lateral cord at the middle third of the arm. Additionally, the brachial artery was bifurcated in the middle third of the arm, creating an atypical vascular arrangement in one case, while the second case displayed a supernumerary bicipital head combined with the atypical morphology of the nerves. Conclusions These combined variations are rarely documented, and dissemination of such morphological diversity is important for medical education purposes. Awareness of complex variations as presented in those cases is critical to understanding diagnostics, vascular access, nerve-related conditions, and planning surgical procedures.